JPH07183247A - Semiconductor device, its manufacture, its evaluating method, and semiconductor manufacturing device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor device having an impurity area at a very shallow depth by forming an impurity film composed of an impurity element and silicon element by heating the active surface of a silicon layer while a gas containing the impurity element is supplied to the surface after performing a cleaning process for exposing the active surface. CONSTITUTION:After performing a cleaning process for exposing the active surface of a silicon layer 1, an impurity film 2 composed of >=80 atomic % of a semiconducting impurity element and >=5 atomic % of silicon element is formed on the surface of the active surface by heating the layer 1 to >600 deg.C while a gas containing the semiconducting impurity element to the surface. For example, a natural oxide film covering the surface of an Si substrate 1 is removed in the first place. Then a boron silicide film 2 is formed on the active surface of the substrate l in the same vacuum chamber. After forming the layer 2, an intended diffusion layer 3 is formed by diffusing boron atoms into the substrate 1 from the film 2 as an impurity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a region having a desired conductivity type and conductivity in a manufacturing process of a semiconductor device represented by a bipolar transistor or an insulated gate field effect transistor used in an electronic system such as a computer. The present invention relates to an impurity diffusion method used for forming a film and a method for manufacturing a thin film used as a diffusion source. More specifically, the present invention relates to a method of diffusing boron that serves as an acceptor in a semiconductor layer and a method of manufacturing a boron silicide film that is an impurity film.

Further, the present invention relates to a method for evaluating an impurity diffusion source film used in an impurity diffusion step of a semiconductor device manufacturing process, and an impurity film semiconductor manufacturing apparatus equipped with the evaluation method. Further, the present invention relates to the structure of a semiconductor device represented by a bipolar transistor or an insulated gate field effect transistor used in a computer or the like. More specifically, it relates to the structures of the active region, control electrode, and contact region of these semiconductor devices.

[0003]

2. Description of the Related Art Conventionally, there is an ion implantation method as a well-known technique for introducing impurities in semiconductor device manufacturing. In this method, accelerated ions are directly implanted into the surface of a silicon substrate, and then the implanted ions are diffused by heat treatment. However, in the ion implantation method, it is difficult to make the diffusion layer thinner than a certain extent due to the so-called channeling effect even if the acceleration voltage is lowered in order to obtain a shallow diffusion layer. The channeling effect is more prominent in boron than in phosphorus or arsenic, which is a great obstacle to the formation of the p-type impurity layer. With the progress of miniaturization of semiconductor devices and the need to make the impurity layer in a silicon substrate shallower, the ion implantation method cannot meet such requirements at present.

Another well-known technique is a solid phase diffusion method. Since this method is also related to the present invention, it will be briefly described with reference to FIG. First, in step A, the Si substrate 21 is prepared. The surface is usually covered with a natural oxide film 22. Next, in step B, a boron impurity-containing glass film such as BS
The G film 23 is formed. The so-called BSG film 23 is predeposited on the Si substrate 21 in a process gas atmosphere containing boron, for example.
Is performed by thermally oxidizing the surface of the.

Finally, in step C, heat treatment is performed to form a boron diffusion layer 26. However, the solid phase diffusion method using an impurity glass such as a BSG film as a diffusion source has the following drawbacks. That is, in the case of boron, which is generally used as a p-type impurity, the diffusion coefficient in glass is smaller than that in a silicon substrate by two digits or more. Therefore, in solid phase diffusion, diffusion of impurities in glass is rate-determining. Therefore, in order to secure a sufficient amount of impurities to be introduced into the silicon substrate, 100
The heat treatment must be performed at a high temperature of 0 ° C or higher. As a result, the impurity layer in the silicon substrate spreads, making it difficult to form a shallow bond.

In view of the above-mentioned drawbacks of the ion implantation method and the impurity glass solid phase diffusion method, a solid phase diffusion method using the impurity film itself as a diffusion source has been developed in recent years. For example, JP-A-63-5
Japanese Patent No. 8823 discloses a technique in which a surface of a silicon substrate is exposed, a boron film is deposited, and then heat treatment is performed to diffuse boron in the silicon substrate. The boron film is formed by a method such as vapor deposition.

Further, in the method for evaluating the thickness of the boron film, after the boron film is formed using the partially patterned oxide film as a mask on the surface of the silicon substrate 1 for film thickness monitoring, the mask film is selectively removed. The film thickness was evaluated by removing it and scanning the surface with a needle to measure the level difference.

Further, in the conventional semiconductor manufacturing apparatus, the ion implantation method is used for forming the active region, that is, the region doped with impurities. Therefore, the distribution of the impurity region was Gaussian, and the impurity concentration on the surface was also below the solid solution limit of silicon.

[0009]

The conventional ion implantation method has a limit in controlling the depth of the impurity layer. In addition, there is no limit to the depth of the impurity layer in principle in solid-phase diffusion using another impurity as a diffusion source, which is another doping method.

However, the solid phase diffusion method using the impurity film itself as a diffusion source has the following problems. An impurity film such as a boron film is deposited on the exposed active surface of the silicon substrate, but does not necessarily have a chemically and physically stable structure. The amount of deposited film and the like greatly change due to the influence of heat treatment and chemical treatment performed during the semiconductor manufacturing process. Since the stability and controllability of the impurity film are difficult, it is difficult to accurately create a depth profile of the impurity concentration.

Further, when impurity doping is performed using a boron or boron silicide film as a diffusion source, evaluation of the film thickness of the impurity film is complicated. That is, in the conventional boron film thickness evaluation method, since the evaluation is performed by mechanical means,
The thin film having a thickness of 00 Å or less has a problem that it cannot be accurately measured. Further, since the needle is in contact with the surface for evaluation, the boron film is scratched. As a result, the wafer is dedicated to the film thickness monitor and cannot be applied to the production wafer. It was Furthermore, the monitor wafer is not a simple monitor wafer, and there is a problem that a monitor wafer having a complicated structure must be prepared before evaluation. That is, due to the problems described above, the impurity diffusion method using the boron film could not be introduced into the production process.

Further, in the method of manufacturing a semiconductor device,
When the ion implantation method is used, there are known problems such as damage and channeling, so that there is a limit to satisfy the demand for shallow junction formation accompanying the miniaturization of semiconductor devices. Therefore, as long as the ion implantation method is used, the structural characteristics of the semiconductor device must reflect the above problems. Therefore, the present invention is to achieve the following objects.

An object of the present invention is to provide a semiconductor device having a very shallow impurity region and a manufacturing method thereof. Further, it is an object of the present invention to provide a semiconductor device having an impurity film that is hardly affected by heat treatment and chemical treatment, and a method for manufacturing the semiconductor device.

A further object of the present invention is to provide a semiconductor device having a low resistance between a wiring metal and a shallow impurity region, and a manufacturing method thereof. A further object of the present invention is to provide a high-density integrated semiconductor device that performs high continuous operation and a manufacturing method thereof.

Another object of the present invention is to provide a semiconductor device having a very high concentration impurity region and a method for manufacturing the same. A further object of the present invention is to provide a method for evaluating a semiconductor device having an impurity film, which evaluates the film thickness of the impurity film with high accuracy and speed.

A further object of the present invention is to provide a semiconductor manufacturing apparatus for forming an impurity film, which can form an extremely thin impurity film with good controllability.

[0017]

In view of the above-mentioned problems of the conventional technique, the present invention utilizes a diffusion source having a film structure that is strong against chemical treatment and physical treatment and has excellent stability and controllability. It is an object to provide a method for diffusing impurities. The following measures have been taken in order to achieve this object. That is, the impurity diffusion method according to the present invention comprises a cleaning step for exposing the active surface of the silicon layer and a boron silicide layer which is a reactive compound of boron and silicon on the active surface. Processing steps. A diffusion step for introducing impurity boron from the boron silicide layer into the silicon layer may be added.

According to one aspect of the present invention, the processing step comprises a deposition step of forming a deposition layer containing boron on an active surface of the silicon layer, and the deposition layer and the silicon layer are thermally reacted to form a boron silicide layer. And a heat treatment step of forming. In this case, a removing step or an etching step of selectively removing the deposited layer containing boron may be performed before the heat treatment step. According to another aspect of the present invention, a coating step of forming a cap film on the boron silicide layer is included prior to the diffusion step. According to yet another aspect of the present invention, a surface treatment step for selectively or entirely etching away the boron silicide layer is included before or after the diffusion step.

Further, in the evaluation of the film thickness of the impurity film,
The boron film was irradiated with light and the reflected light was analyzed to evaluate the film thickness. Furthermore, the film forming apparatus is a manufacturing apparatus for forming an impurity film while evaluating the film thickness by the evaluation method of the present invention. Further, in the case of a value deviating from the desired film thickness, the impurity diffusion method is used in which the film thickness is controlled so as to be the value and then the diffusion process is performed.

Further, the semiconductor device of the present invention has a laminated structure of a boron silicide region and an impurity-doped semiconductor region. Further, the semiconductor region was formed to be extremely shallow by making the depth of the semiconductor region formed by diffusion equal to or smaller than the film thickness of the boron silicide region.

[0021]

In the semiconductor manufacturing method of the present invention, the boron silicide layer is formed in direct contact with the surface of the silicon layer, and if necessary, this is used as a diffusion source for solid phase diffusion. By controlling the composition of the boron silicide layer, the layer thickness, the diffusion treatment temperature, the diffusion treatment time, etc., a boron diffusion layer having a desired concentration profile in the depth direction can be formed. In particular, it is possible to form an extremely thin impurity diffusion layer that is essential for miniaturization of semiconductor elements. Since the boron silicide film is chemically and physically stable as compared with the boron film that has been conventionally used as a diffusion source, process control is facilitated and the process design is diversified, and the degree of freedom is increased.

In order to form the boron silicide layer, for example, a deposited layer containing boron is once formed on the active surface of the silicon layer, and then the deposited layer and the silicon layer are thermally reacted. Unlike the boron silicide layer, the deposited layer containing boron is chemically or physically unstable and can be easily etched. Therefore, a desired impurity diffusion region can be obtained by selectively removing the deposited layer containing boron in advance.

When solid phase diffusion is performed using a boron silicide layer as a diffusion source, it may be necessary to suppress so-called out diffusion. In this case, a cap film having a desired composition may be formed on the boron silicide prior to the diffusion process. The boron silicide layer serving as the diffusion source may be left as it is in the finished device. However, it can be selectively removed particularly when the resistance of the electrical connection is reduced. In this case, it can be etched by performing a specific surface treatment.

Further, in the method for evaluating the thickness of a boron film or a boron silicon compound film, which is the method for evaluating a semiconductor device of the present invention, since the film thickness is evaluated by an optical means, the accuracy of the wavelength level of light is improved. It is possible to evaluate a film thickness of 100 Å or less. Further, since the non-contact measurement is performed, the measured wafer can be used as a production wafer. In addition, the evaluation can be performed while forming the impurity film. Further, since it becomes possible to perform diffusion from the boron film whose thickness is controlled, the resistance value of the diffusion layer formed after the diffusion can be formed with high accuracy.

Further, in the semiconductor device of the present invention, the laminated structure of the semiconductor region and the boron silicide realizes the following operation as a constituent requirement of the semiconductor device. First
In addition, since it is a semiconductor region doped with a high concentration of impurities without using ion implantation, a characteristic as a semiconductor device that is not affected by channeling and shadowing, that is,
In the MISFET, a shallow junction source / drain region and excellent symmetry of device characteristics can be obtained, and in a bipolar transistor, a thin base region can be realized and an impurity profile without an emitter push effect can be obtained.

Second, the boron silicide film itself functions as a barrier layer for suppressing the metal spike phenomenon in the contact region and the like. Further, from the viewpoint of manufacturing a semiconductor manufacturing device, the semiconductor device having the structure of the present invention has the following advantages. That is, firstly, the boron silicide film is chemically and physically stable as compared with the conventional boron film used as the diffusion source, so that the process control becomes easy and the process design can be diversified. . Secondly, since the boron silicide film itself contains a sufficient amount of boron, the phenomenon of migration of impurities from the semiconductor region to the wiring, which has been a problem in the past, such as the junction between the P ⁺ semiconductor region and the tungsten silicide film. There is an advantage that boron can be effectively compensated for a phenomenon such as the absorption of boron into the tungsten silicide film in the portion.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a process diagram showing a first embodiment of an impurity diffusion method according to the present invention. First, in step A, cleaning is performed to expose the silicon layer, that is, the active surface of the Si substrate 1. When an oxide film or the like is present on the surface of the Si substrate 1, the oxide film is removed by general HF or the like, and then the natural oxide film is further removed. Specifically, the natural oxide film covering the surface of the Si substrate 1 is removed. In the case of only a simple HF treatment, the native oxide film grows as soon as the wafer is exposed to the air. Therefore, this step is necessary for preventing the formation of the natural oxide film and for removing the natural oxide film when it is formed. For this purpose, the Si substrate 1 is set in a vacuum chamber having a background pressure of 1 × 10 ⁻⁴ Pa or less, and then hydrogen gas is introduced for a certain period of time while the substrate is heated to 850 ° C. or more. The conditions in this case are, for example, filling with hydrogen gas until the pressure inside the chamber reaches 1.3 × 10 ^-2 Pa. By this treatment, the natural oxide film formed on the surface of the Si substrate 1 is removed to expose the chemically active silicon surface, and the state is maintained. Instead of this method, the natural oxide film may be removed by dilute hydrofluoric acid etching or argon sputtering in vacuum, but it is necessary to immediately proceed to the next step.

FIG. 3 is a graph showing the relationship between the degree of background vacuum (1 Torr = 133 Pa) in the process A and the in-wafer variation of the diffusion layer sheet resistance after the diffusion after the final completion. Vacuum degree is 5 × 10 ^-7 torr
In the case of, the dispersion of the diffusion layer sheet resistance is as bad as 5% or more. It is considered that if the degree of vacuum is low, a clean silicon surface is exposed and cannot be maintained.

Subsequently, in step B, a boron silicide film 2 is formed on the active surface in the same vacuum chamber as in step A. In this embodiment, the boron silicide film 2 is formed by utilizing the vapor phase thermal reaction. Specifically, a process gas containing boron, for example, diborane (B ₂ H ₆ ) is introduced into the vacuum chamber at a predetermined pressure, and the Si substrate 1 is heated to 60%.
Heat above 0 ° C. As a result, boron atoms, which are impurity atoms generated by thermal decomposition of the process gas, or molecules containing boron and silicon atoms in the substrate directly react with each other to form a boron silicon compound, so-called boron silicide. In the present invention, a compound containing 80% or more of impurity atomic boron and 5% to 20% of atomic percent of silicon is referred to as boron silicide. This reaction proceeds simultaneously upward and downward with respect to the original Si surface 119. In the step of forming the boron silicide film 2, when the heat treatment temperature is set to 850 ° C. or higher and the heat treatment time is set to several minutes or longer, the boron silicide film 2 is simultaneously formed.
Is introduced into the Si substrate 1 to form a boron diffusion layer. Therefore, the heat treatment temperature for silicidation is preferably 850 ° C. or lower at which diffusion does not occur.

The composition of the boron silicide film thus formed is shown in FIG. In this graph, the vertical axis represents the Si content (atomic%) in boron silicide, and the horizontal axis represents the substrate heating temperature or the film forming temperature. Boron content is almost everything except silicon content. That is, oxygen atoms were at levels below 1% in our experiments. As is clear from the graph, the Si content has a dependency on the film forming temperature. The Si content increases as the film formation temperature is increased, and is saturated at 20% or less at 900 ° C. or higher.
Therefore, the boron content is always 80% or more. This amount is sufficiently larger than the solid solubility limit of boron atoms in the silicon substrate. Boron silicide requires a silicon content of 5% or more in order to form a chemically and physically stable diffusion source. For this reason, as is apparent from the graph of FIG. Need to set higher temperature.

Then, as shown in the process diagram of FIG.
In, the boron atoms, which are impurities, are diffused from the boron silicide film 2 into the silicon substrate 1 to obtain the intended diffusion layer 3. The diffusion temperature is set higher than the temperature in step B.
FIG. 5 shows the result of measuring the resistivity of the boron diffusion layer 3 after the step C shown in FIG. In this graph, the vertical axis represents the sheet resistance (Ω / □) of the boron diffusion layer, and the horizontal axis represents the thickness of the boron silicide film (SiB film) in Angstrom units. In obtaining this data, the boron silicide layer was formed at 900 ° C. The diffusion process was also performed at the same temperature of 900 ° C. As is clear from the graph, stable sheet resistance can be obtained when the SiB film is formed to a thickness of 100 angstroms or more. It can be seen that the sheet resistance is constant even if the SiB film is thickened, and that the boron diffusion concentration does not depend on the SiB film thickness. Therefore,
If the thickness of the SiB film is 100 angstroms or more, uniform doping can be performed even if the thickness varies.

Further, since boron atoms having a solid solubility limit or more are sufficiently diffused into the silicon substrate during diffusion from the boron silicide film, the boron silicide film contains boron atoms having a solid solubility limit or more. The diffusion coefficient of boron in the film needs to be sufficiently larger than the diffusion coefficient of boron in the silicon substrate. Therefore, the silicon content of the boron silicide film cannot be increased so much.

In the present invention, before forming the boron silicide layer, a natural oxide film on the silicon substrate is removed to perform a cleaning process for exposing the active surface. FIG. 6 shows the effect of the cleaning process. In this graph, the vertical axis represents the sheet resistance ρ _S of the boron diffusion layer, and the horizontal axis represents the thickness of the SiO ₂ natural oxide film before the silicon substrate cleaning step. In the sample used to obtain the data of this graph, the thermal diffusion treatment temperature is set to 900 ° C. As is apparent from the graph, when the natural oxide film is removed to about 10 Å or less, a sheet resistance of 100Ω or less is obtained. That is, the boron atoms in the vapor phase and the silicon on the substrate can directly and easily react to form a boron silicide film. Further, direct solid phase diffusion using the boron silicide layer as a diffusion source and not through the natural oxide film is sufficiently performed. On the other hand, if the natural oxide film is left over 10 angstroms or more, the sheet resistance of the boron diffusion layer sharply increases, and it is understood that the impurity diffusion is not sufficiently performed.
That is, a stable boron silicide film is not formed due to the presence of the natural oxide film. In other words, the boron silicide film is selectively formed only in the region of the natural oxide film having a thickness of 10 Å or less. As described above, the step of cleaning the silicon substrate is important in carrying out the impurity diffusion method according to the present invention.

It is difficult to control the natural oxide film to 10 angstroms or less only by the conventional simple HF treatment. Silicon-activated surfaces oxidize immediately at room temperature when exposed to air. Therefore, the cleaning step of the present invention is a step of removing the natural oxide film and maintaining the state, and within the range confirmed by our experiments,
It is at a level of 0 angstroms or less and whether or not a very thin oxide film exists.

Next, the growth mechanism of the boron silicide film will be described with reference to FIG. Boron silicide film or Si-B film is formed by Etching method and Lift off
Method. By comparing the film thicknesses obtained by these two different measurement methods, it is possible to determine whether the formation of the boron silicide film is the deposition type or the thermal reaction type. In the Etching method, after a part of the formed boron silicide film is masked with a sputtered SiO ₂ film, the boron silicide film is etched by performing a cycle treatment of nitric acid and hydrofluoric acid, and then the SiO ₂ film mask is removed. After that, the film thickness a is measured by a step gauge. In this measurement, a sample in which a boron silicide film was formed at a heat treatment temperature of 800 ° C. was used. On the other hand, Lift
In the off method, a part of the Si substrate is previously made into Si.
A boron silicide film is formed in a state of being masked by the O ₂ film, the SiO ₂ film mask is subsequently removed, and then the film thickness b is measured by a step gauge. In order to apply the present invention in a semiconductor manufacturing process, it is necessary to more easily evaluate the impurity film thickness. The method will be described later.

The measurement results are shown in Table 1 below. In this measurement, samples of condition 1 in which the process gas introduction time for forming the boron silicide film was set to 600 seconds and condition 2 in which the process gas introduction time was set to 1000 seconds were used. As can be seen from Table 1, in the case of condition 1, the step difference b measured by the Lift off method
Is 37 Å, while Etchi
The step a measured by the ng method was 84 Å. Further, under the condition 2, the step difference b measured by the Lift off method is 65 Å, and the Etching
The step a measured by the method was 140 Å. The film thickness measured by the Etching method shows a larger value. Therefore, the silicon in the boron silicide film is contained by the reaction of the process gas such as diborane with the silicon substrate, and it is presumed that the boron silicide film is formed not by the deposition type but by the thermal reaction type. .

By this forming mechanism, the silicon film is effectively and selectively formed on the exposed surface of the silicon substrate. It is not effectively formed on the oxide film, and a film in which three atoms of oxygen, boron and silicon are distributed from the surface is formed. This membrane is
It is considered that boron is an oxide film diffused from the surface, and is not the boron silicide film of the present invention.

[0038]

[Table 1]

FIG. 8 shows a concentration profile in the depth direction of the boron diffusion layer. In this graph, the vertical axis shows the boron concentration (pieces /
cm ³ ) and the depth (nm) on the horizontal axis.
Note that this concentration profile shows SIMS for samples with the thermal diffusion temperature set to 900 ° C and the thermal diffusion processing time changed.
It was measured using. The longer the heat treatment time, the deeper the boron diffusion layer becomes. However, the boron concentration on the surface of the diffusion layer is constant at about 8 × 10 ¹⁹ / cm ³ within the heat treatment time of 10 to 60 minutes. This is considered to be the solid solubility limit of boron in silicon.

FIG. 9 shows the result of an experiment conducted on the chemical resistance of the boron silicide film. After forming the boron silicide film, a chemical treatment was performed using a plurality of chemicals prior to the diffusion treatment. Then, the sheet resistance ρ _S of the boron diffusion layer was measured. For comparison, the level of sheet resistance measured for the sample not subjected to the chemical treatment is shown by a dotted line. When chemically treated with nitric acid and hot nitric acid, the sheet resistance is slightly increased as compared with the untreated sample. However, the fluctuation range is slight and is hardly affected by the chemical treatment. Further, the sheet resistance hardly changes when treated with sulfuric acid, sulfuric acid + hydrogen peroxide solution, hydrofluoric acid, or phosphoric acid. Thus, it can be seen that the boron silicide film is chemically extremely stable.

For comparison, FIG. 10 shows the chemical resistance of the boron film. This data is obtained by measuring the sheet resistance of the boron diffusion layer obtained by the diffusion treatment using the boron film as the solid phase diffusion source. After the boron film is formed, it is chemically treated with multiple chemicals prior to the diffusion treatment. As a reference, the level of the sheet resistance measured for the sample not chemically treated is shown by a dotted line. Nitric acid, sulfuric acid / hydrogen peroxide,
When treated with hydrofluoric acid, the sheet resistance increases slightly. When treated with hot nitric acid, the sheet resistance greatly changed to 3 kΩ / □. This is because the boron film was dissolved by the hot nitric acid treatment and was not sufficiently diffused. Thus, the boron film is inferior in chemical resistance to the boron silicide film.

A second embodiment of the impurity diffusion method according to the present invention will be described with reference to FIG. First, in step A, S
The native oxide film existing on the surface of the i-substrate 101 is removed and cleaning is performed. This step is similar to step A shown in FIG. Next, in step B, a boron film 102 is deposited on the exposed active surface of the Si substrate 101. First shown in FIG.
Unlike the embodiment, in the present embodiment, the boron silicide film is not directly formed on the substrate surface, but the boron film 102 is once formed. Next, in step C, the boron film 102 is converted into the boron silicide film 103. The boron film is chemically unstable as compared with the boron silicide film. For example, if it is left in the air, it will be oxidized. Therefore, it is preferable that after the boron film 102 is formed, it is stored in an N ₂ atmosphere or is immediately silicidized. At the same time Si
A very shallow boron diffusion layer is formed between the substrate 101 and the boron silicide film 103. Finally, in step D, the boron atoms of the boron silicide film 103 are removed from the silicon substrate 1.
Spread to 01. This step D is performed in the same manner as step C shown in FIG. Further, by performing the diffusion process at a temperature higher than that of silicidation in the process D, the boron diffusion layer 104 can be freely controlled. For example, the diffusion surface concentration can be increased by increasing the additional diffusion temperature. This is because the surface concentration becomes a concentration determined by the solid solubility limit.

Process B, which is a feature of this embodiment, will be described in detail below. After the cleaning of the substrate surface is completed in step A, the introduction of the hydrogen gas used to remove the natural oxide film is stopped and the substrate temperature is set to a predetermined level below 700 ° C. that does not cause silicidation. After reaching the set temperature and stabilizing, the surface of the Si substrate 101 is diborane (B ₂ H) which is a process gas containing boron or a boron compound gas.
₆ ), for example, if the pressure in the vacuum chamber is 1.3 × 10 ^-2 Pa
The boron film 102 is formed by introducing the boron film 102 for a certain period of time under the following conditions. The substrate temperature is set to a level lower than the level of 700 ° C. required for the pyrolysis of diborane and progress of boron deposition. Preferably, a high deposition rate is 7
It is below 500C and above 500C. In the case of a CVD film,
If the temperature is 400 ° C. or lower, the boron film 102 becomes a film containing a large amount of hydrogen. The boron film deposition process may be performed at 700 ° C. or higher. In this case, it is considered that the formation of the boron silicide film 103 also partially progresses at the same time, as inferred from the graph shown in FIG. By adjusting the substrate temperature, the introduction pressure of diborane gas, and the introduction time, the adsorption amount of boron, that is, the thickness of the boron film 102 can be set. The boron film is selectively formed only on the exposed surface of the silicon substrate in the thin film thickness range. This boron film 102 is converted into a boron silicide film 103 in step C. In this case, the boron silicide film 103 is formed by reacting boron atoms in the boron film 102 with silicon in the silicon substrate 101. Therefore, only the boron film 102 formed on the exposed surface of the silicon substrate is selectively boron film 103.
Converted to. When the boron film is formed on the oxide film, the boron in the boron film only diffuses in the oxide film. Further, if necessary, in step D, the boron diffusion layer 104 is formed by using the boron silicide film 103 as a solid phase diffusion source.
Is formed.

In this embodiment, a vapor phase pyrolysis reaction and adsorption of diborane gas are used as a method of forming the boron film 102. However, the present invention is not limited to this, and the boron film 102 can be deposited using another method. For example, the molecular beam epitaxial growth method (MBE
Method) or a chemical vapor deposition method (CVD method).
Alternatively, a physical vapor deposition method such as vacuum deposition or sputtering (P
VD method) may be used. Furthermore, it is also possible to use a spin coating method or the like. Therefore, low temperature formation at room temperature level is also possible.

In this embodiment, the boron film 102 is once formed and then heat-treated to convert it into the boron silicide film 103. As described above, the boron film 102 is inferior in chemical stability to the boron silicide film 103. In other words, the boron film 102 can be easily etched using a predetermined chemical. Therefore, when selectively forming the boron diffusion layer 104 or the boron diffusion region, it is preferable to adopt this embodiment and pattern the boron film 102. As can be understood from the graph shown in FIG. 10, hot nitric acid can be used as the etching solution. Note that ion milling or dry etching may be performed instead of wet etching.

The boron silicide film and the boron film have completely different chemical properties. This property can be used to make the film thickness of the boron silicide film uniform. First,
A case where B ₂ H ₆ is supplied at a temperature of 600 ° C. or higher to form an impurity film on the surface of a silicon substrate will be described. In this case, the silicidation reaction is controlled so as to partially silicidize not the entire impurity film. That is, as the impurity film, a uniform boron silicide film controlled by a silicidation reaction is formed on the silicon substrate side, and a non-silicided boron film is formed with an uneven film thickness on the boron silicide film. Then, only the boron film is selectively removed by utilizing the difference in chemical property. After removing the boron film, a boron silicide film having a uniform film thickness controlled by the silicide reaction remains. As another method for forming a uniform film thickness of boron silicide, first, B ₂ H ₆ is supplied at a temperature of 600 ° C. or lower to form a boron film.

Next, part of the boron film is silicidized at a temperature of about 700.degree. Next, by selectively removing only the non-silicided boron film, a boron silicide film having a uniform film thickness can be left. A third embodiment of the impurity diffusion method according to the present invention will be described with reference to FIG. In the first and second embodiments described so far, the silicon atoms of the boron silicide film are supplied by the substrate silicon. The third embodiment is different in that not only boron atoms but also silicon atoms are supplied by the supply gas. First, in step A, the natural oxide film existing on the surface of the Si substrate 301 is removed and cleaning is performed. This process is the same as that of Example 1 and Example 2. Next, in step B, as a gas for forming a boron silicide film, Siborane (B ₂ H ₆ ) and dichlorosilane (SiH ₂ Cl ₂ ) are supplied to the exposed active surface of the Si substrate 301. The temperature of the vacuum chamber and the temperature of the wafer are heated to 800 ° C. Syborane 1 × 10 ^-3 torr and dichlorosilane 1 × 10 ^-6
In case of more than torr, Si substrate 3 at about 10Å / min
A boron silicide film is selectively deposited on the surface of 01. In the case of the third embodiment, the boron silicide film 302 is
It is deposited above the surface of the Si substrate 301. in this case,
Both the boron atom and the silicon atom are supplied from the outside by thermal decomposition of the gas to form a boron silicide film, so that the film is a deposition type film. If silane (SiH ₄ ) is used as a gas for supplying silicon atoms, a boron silicide film can be formed at a low temperature of about 500 ° C.

Subsequently, if necessary, in step C, the boron atoms in the boron silicide film can be thermally diffused into the silicon substrate 301 to obtain the boron diffusion layer 303. Third
The embodiment is different from the conventional silicon epitaxial technology containing impurity atoms in the following points. That is, the composition of the boron silicide film of the present invention is a film mainly containing boron. Boron atoms contain more than the solid solubility limit in silicon, and the boron content is 50% or more with respect to the whole. In the conventional epitaxial technology, the boron content is less than the solid solubility limit. The main organization is also silicon.

A fourth embodiment of the impurity diffusion method according to the present invention will be described with reference to FIG. This embodiment is an improvement of the above-described second embodiment, and is for preventing the diffusion of boron atoms from the so-called boron film at the time of silicidation and the silicide film at the time of diffusion (out diffusion) or preventing the oxidation of the boron film. Therefore, the feature is that a cap film is formed. First, in step A, the surface of the Si substrate 111 is cleaned. Next, in step B, a boron film 112 is deposited on the surface of the Si substrate 111. This step is performed in the same manner as step B shown in FIG. Subsequently, in step C, the cap film 113 is coated on the boron film 112.

Next, in step D, heat treatment is performed at a substrate temperature of 700 ° C. or higher to convert the boron film 112 into a boron silicide film 114. If necessary, finally, in step E, boron is diffused into the substrate 111 using the boron silicide film 114 as a diffusion source. As a result, the boron diffusion layer 115 is simultaneously formed at the interface between the Si substrate 111 and the boron silicide film 114, and the out diffusion can be prevented by the cap film 113. That is, the cap film 1
Numeral 13 prevents boron from being diffused from the boron silicide film 114 with respect to a film (not shown) formed thereon. As the material of the cap film, for example, a silicon nitride film is used and is formed by the CVD method or the like. The formation temperature of the cap film is lower than 700 ° C. at which the boron film is not silicidized. A fifth embodiment of the impurity diffusion method according to the present invention will be described with reference to FIG. First, in step A, the surface of the Si substrate 121 is cleaned. Next, in step B, the boron silicide film 122 is directly formed on the surface of the cleaned Si substrate 121. At this time, the substrate is 700 ℃
Since the heating is performed as described above, the boron diffusion layer 123 is simultaneously formed between the boron silicide film 122 and the Si substrate 121. That is, in step B, thermal diffusion treatment is also performed to remove impurity boron from the boron silicide film 122 into the silicon substrate 12.
Introduce to 1.

As described above, the present embodiment is different from the first embodiment shown in FIG. 1 in that the treatment process for forming the boron silicide layer and the diffusion process are the same. By adjusting the substrate heating temperature and heating time in the diffusion step B and the processing step for forming the boron silicide layer, the boron diffusion layer 123 having a desired depth direction impurity concentration profile can be obtained. For example, the profile when the heat treatment time is changed is shown in the graph of FIG.
Also, regarding the substrate heating temperature or annealing temperature, 11
It is set in the range up to about 00 ° C.

However, generally, conditions such as temperature and atmosphere are set separately for the boron silicide layer forming step and the diffusion step. When set separately, the diffusion process or the annealing process is performed in a vacuum or in an inert gas atmosphere. Thereby, the impurity atom boron is activated at the same time as the formation of the boron diffusion layer 123 using the boron silicide film 122 as a diffusion source. The impurity boron diffusion layer 123 having a desired impurity concentration and junction depth can be formed by controlling the annealing conditions, that is, the substrate temperature and the heating time. In this embodiment, annealing is carried out in the same vacuum chamber subsequent to the formation of the boron silicide film 122, but the present invention is not limited to this. The substrate may be taken out of the vacuum chamber and subjected to lamp annealing by another device.

Care must be taken when setting the heat treatment conditions after forming the boron silicide film. FIG. 15 shows 800
900 using boron silicide film formed at ℃ as a diffusion source
6 is a graph showing the sheet resistance of the diffusion layer in the case of thermal diffusion in a N ₂ atmosphere at ℃. The horizontal axis shows the time of leaving at 800 ° C. before annealing at 900 ° C. The vertical axis represents the sheet resistance of the diffusion layer after annealing at 900 ° C. and the variation within the wafer surface. N _{2 at} 800 ℃
And O ₂ respectively. As is clear from FIG.
A small amount of oxygen is included in the atmosphere even at a low temperature up to 900 ° C. annealing, so that the sheet resistance changes greatly. When the time is short (30 minutes or less at 800 ° C.), accelerated diffusion occurs. On the other hand, if the time is long (80
If the temperature is 0 ° C. for 30 minutes or more), the boron silicide film is oxidized and the sheet resistance increases. Therefore,
The temperature / atmosphere and time leading to the annealing process also need to be controlled. It is desirable to carry out the annealing treatment while maintaining the atmosphere in which oxidation is not introduced. If oxygen enters, it is necessary to control time and pressure.

FIG. 16 shows the sheet resistance of the diffusion layer when the boron silicide film formed at 800 ° C. is annealed and diffused in a N ₂ atmosphere at 900 ° C. as a diffusion source and then left at 800 ° C. while being cooled to room temperature. And the in-plane variation of the wafer. The abscissa represents the standing time at 800 ° C. As is clear from this figure, even after annealing, the sheet resistance increases due to being oxidized by oxygen.

From the above, the heat treatment after forming the boron silicide film is not limited to the annealing treatment, but may be performed in an inert atmosphere or high vacuum in which oxygen does not enter not only in the low temperature treatment before and after the annealing treatment. is necessary. This annealing step is preferably performed in an inert atmosphere such as vacuum or nitrogen gas. If it is performed in an active atmosphere containing oxygen gas, water, etc., the surface of the boron silicide film is oxidized and the sheet resistance of the boron diffusion layer varies. FIG. 17 is a micrograph showing a change in the surface state of the boron silicide film caused by annealing in an active atmosphere. After annealing, fine particles are partially generated on the surface of the wafer and the appearance becomes cloudy. Observing this cloudy portion at a magnification of 1000 times shows that fine particles of boron oxide and boron silicon oxide are formed. The sheet resistance of this part is very high. It is considered that the boron silicide film was oxidized and became difficult to diffuse due to the entry of oxygen.

Table 2 shows the state of generation of fine particles when annealing is performed in different atmospheres. In Table 2, the horizontal column shows the annealing temperature, and the vertical column shows the annealing atmosphere. A circle indicates that fine particles were not generated, and a cross indicates that fine particles were generated. As is clear from Table 2, fine particles are not generated at any substrate temperature when annealing is performed in a vacuum or a nitrogen gas atmosphere. On the other hand, when annealing is performed in an oxygen gas atmosphere, 50
In the range of 0 ° C to 800 ° C, the surface of the boron silicide film is oxidized and fine particles are generated. Similarly, fine particles are generated when annealing is performed in an atmosphere containing water.

In order to prevent the generation of such fine particles, it is necessary to diffuse at a temperature higher than 800.degree. Furthermore, when performing a high temperature diffusion process, the ramping-up speed up to a high temperature or the ramping-down speed when lowering from a high temperature needs to be 10 ° C./min or more. By increasing the ramping-up and ramping-down speeds, it is possible to shorten the processing time in the range of 500 to 800 ° C. and prevent the generation of fine particles. The temperature for putting in and out of the annealing device from room temperature needs to be lower than 500 ° C. When the temperature is 500 ° C or higher, fine particles are generated.

[0058]

[Table 2]

When a semiconductor device is manufactured by using the impurity diffusion method according to the present invention, it may be necessary to remove the boron silicide film used as the solid phase diffusion source in some cases. However, the boron silicide film is extremely stable chemically and physically as described above, and the etching process is relatively difficult. In such a case, the removal process can be facilitated by reversely utilizing the oxidation phenomenon of the boron silicide film described above. FIG. 18 shows an example of this removal processing. The boron silicide film 2 formed directly on the surface of the Si substrate 1 is once oxidized. For example, wet oxidation may be performed at a substrate temperature of 400 ° C. to 800 ° C. for about 5 minutes. Of course, dry oxidation may be used instead of wet oxidation. In this way
The boron silicide film is converted into the oxide film 401. Unlike the boron silicide film, the oxide film has poor chemical resistance and can be easily removed by etching. For example, it can be easily removed by applying hydrofluoric acid treatment. For reference, FIG. 18 shows the concentration profile of the boron silicide film and the concentration profile after the oxidation treatment. As is clear from a comparison of both concentration profiles, it is found that a large amount of oxygen atoms are introduced into the boron silicide film composition after the oxidation treatment.

FIG. 19 is a graph showing the oxidation characteristics of the boron silicide film. The vertical axis represents the boron silicide film thickness before and after oxidation and the sheet resistance of the diffusion layer after annealing. Before the oxidation treatment, a boron silicide film of about 130 Å was present. It is easily oxidized by oxidizing at about 600 ° C., and the thickness of the boron silicide film is reduced. The oxidation rate is much slower than the boron film and much faster than the silicon substrate. That is, the boron film is oxidized even at 400 ° C. or lower, but the boron silicide film is slightly oxidized. On the other hand, the silicon substrate is hardly oxidized below 800 ° C., but the boron silicide film is easily oxidized. Therefore, by selectively oxidizing only the boron silicide film in the range of 400 ° C. to 800 ° C. and then removing the oxide film with HF or the like, the boron silicide film is selectively removed while maintaining the structure below the substrate surface. Can be removed. If the oxidation step is performed at 800 ° C. or higher, the silicon substrate is also oxidized, which is not preferable.

A sixth embodiment of the impurity diffusion method according to the present invention will be described with reference to FIG. First, as in the previous embodiment, in step A, the surface of the Si substrate 151 is cleaned or activated. Subsequently, in step B, a boron silicide film 152 is formed on the surface of the Si substrate 151. This step B is performed, for example, similarly to the step B of the first embodiment shown in FIG. Further, in step C, a cap film 153 is formed on the boron silicide film 152. This cap film 15
3 is for preventing out diffusion.

Incidentally, the process C of the fourth embodiment shown in FIG.
In the above, the cap film 113 was formed on the boron film 112, but in the present embodiment, unlike this, the cap film 153 is formed on the boron silicide film 152. Finally, in step D, a thermal diffusion process is performed to form a boron diffusion layer 154 at the interface between the boron silicide film 152 and the Si substrate 151. This step D is performed, for example, similarly to the step C of the first embodiment shown in FIG. Cap film 1
By using 53, out diffusion can be suppressed and the uniformity of the sheet resistance of the boron diffusion layer 154 is improved.

A silicon nitride film or a silicon oxynitride film is preferable as the cap film, and for example, a Si ₃ N ₄ film and a SiON film deposited by the CVD method are used. The formation temperature is preferably a low temperature of 850 ° C. or lower at which a large amount of boron atoms do not diffuse into the substrate 151. Since the diffusion rate of boron atoms in the silicon nitride film and the silicon oxynitride film is extremely low, it is suitable as a cap film. Figure 21
Figure 3 shows the boron atom concentration profile when a silicon nitride film is used as a barrier. The sample used for this measurement has a layered structure in which a boron film is deposited on the surface of a silicon substrate via a nitride film, and is an AES analysis of the profile in the depth direction after the annealing treatment. As is clear from the profile of FIG. 21, boron atoms are almost completely blocked by the silicon nitride film and never reach the silicon substrate. That is, by forming the silicon nitride film as the cap film on the boron silicide film, it is possible to prevent the boron atoms in the boron silicide film from diffusing to the outside air.

For comparison, FIG. 22 shows a concentration profile when a silicon oxide film is used as a barrier instead of the silicon nitride film. Boron atoms have a relatively high diffusion rate in the silicon oxide film, and boron easily penetrates into the silicon oxide film. In the profile shown in FIG. 22, since the silicon oxide film has a large thickness, boron atoms have not reached the silicon substrate. However, when the annealing temperature is increased and the annealing time is lengthened, the boron passes through the silicon oxide film barrier. It is diffused into the silicon substrate.

FIG. 23 shows the results of measuring the variations in the sheet resistance ρ _S of the diffusion layer when the diffusion treatment was performed using the cap film and when the diffusion treatment was performed without using the cap film. The average value of the sheet resistance of the diffusion layer was 72.9 Ω / □ when the cap film (SiN) was used in the steps shown in A, B, C and D of this figure. The variation σ _S was 4.2% with respect to the average chamber ρ _S of the sheet resistance. On the other hand, FIGS. 23E, F, and G show the case where diffusion is performed without using the cap film 411. At this time, the average value of the sheet resistance of the diffusion layer 3 was 80.1 Ω / □. The variation σS was 9.7% with respect to the average value of the sheet resistance. Thus, by using the cap film 411, it is possible to prevent the oxidation of the boron silicide film at the time of out-diffusion and diffusion processing and suppress the variation of the sheet resistance of the impurity diffusion layer 3 to half or less.

A seventh embodiment of the impurity diffusion method according to the present invention will be described with reference to FIG. Si substrate 1 in step A
A boron silicide film 192 is formed on the surface of 91, and solid phase diffusion is performed using this as a diffusion source to form a boron diffusion layer 193.
To form. This step A is the same as the first to sixth embodiments described above. The feature of this embodiment lies in the next step B, and the boron silicide film 192 used as the diffusion source remaining after the diffusion step is removed. This removal is
For example, this is performed in order to reduce the electric contact with the boron diffusion layer 193, and the boron silicide film 192 is selectively or entirely etched. Since the boron silicide film 192 has a relatively high resistance, it may be necessary to remove it in order to reduce the resistance of the contact. In step B, the boron silicide film 192 is removed by wet etching using a mixed solution of HF and HNO ₃ . Finally, in step C, the boron diffusion layer 19
A metal film 195 for direct wiring is formed on the surface of No. 3. As the material of the metal film 195, metals such as Ti, Co, Mo, W can be used. Alternatively, instead of this, high-concentration impurity-doped polysilicon or amorphous silicon may be used.

Instead of the step B, a removing process consisting of the steps B1 and B2 may be adopted. First, in step B1, the boron silicide film is converted into a film 194 made of boron oxide and silicon oxide. For this step, for example, the processing described with reference to FIG. 19 can be used as it is.
As described above, the film 194 made of boron oxide and silicon oxide is inferior in chemical stability and physical stability to the boron silicide film 192 and can be easily removed. For example, it can be removed by performing a wet etch using HF in the subsequent step B2. Alternatively, dry etching may be performed using F-based or Cl-based accelerated particles instead of the steps B1 and B2.

An eighth embodiment of the method of manufacturing a semiconductor device according to the present invention will be described with reference to FIG. MO in this example
The impurity diffusion method according to the present invention is used to form the source / drain regions of the S transistor. First, in step A, the surface of the N-type Si substrate 201 is LOCOSed.
An element isolation region 202 made of a field oxide film is formed by oxidation. A gate electrode 204 is formed in an active region surrounded by the element isolation region 202 with a gate insulating film 203 interposed. Further, the surface of the gate electrode 204 is covered with an oxide film 205.
Cover with. Next, the oxide film 205 on the surface of the substrate to be doped by HF treatment is etched. Then, the wafer is placed in a high vacuum chamber to remove the natural oxide film of about 20 Å left on the surface of the N-type Si substrate 201 to clean the surface of the active region.

Next, in step B in the same chamber, a boron film 206 is deposited on the entire surface of the substrate in succession to the removal of the natural oxide film in step A. In this embodiment, the substrate temperature is 600 ° C.
The deposition treatment was performed by introducing diborane gas B ₂ H ₆ for 2000 seconds at a partial pressure of 5 × 10 ^-5 Torr. The film thickness of the boron film 206 adsorbed at this time was 500 angstrom. When performing this adsorption treatment, it is generally preferable to set the substrate temperature to 300 to 700 ° C.

Next, in step C, the boron film 206 is converted into the boron silicide film 207. For example, the substrate temperature is 8
Annealing is performed for 60 minutes in a vacuum or an inert atmosphere in nitrogen gas while keeping the temperature at 00 ° C. By this process S
The boron film adsorbed on the active surface of the i-substrate 201 is selectively converted into the boron silicide film 207. At this time, when the B film is adsorbed on the element isolation region 202 and the oxide film 205, since it is not in direct contact with the Si substrate 201, it is diffused into the oxide film when the film thickness is thin, but when it is thick. It is left as it is. In addition, it is preferable that the thermal reaction treatment is generally performed at a substrate temperature of 700 to 1200 ° C. and in an inert atmosphere without oxygen and water so as not to be oxidized.

Next, in step D, the remaining boron film 2
06 is selectively removed. For example, the boron film 206 can be removed by acting nitric acid on the substrate surface. Since the boron silicide film 207 is insoluble in nitric acid, it is left as it is. Finally, if necessary, annealing is performed in step E to form a source region 208 and a drain region 209 using the boron silicide film 207 as a diffusion source. The annealing temperature or the thermal diffusion treatment temperature in the step E is preferably set higher than the boron silicide film forming treatment temperature in the step C. According to this application example,
Since only the source region 208 and the drain region 209 are silicided, the B film can be selectively and easily removed from other unnecessary regions.

In the silicide process of the process D of FIG. 25, the diffusion phenomenon actually progresses. Therefore, the diffusion step of step E may be omitted. In this case, the diffusion region can be formed extremely shallow and can be made shallower than the thickness of the boron silicide film. Figure 2
A ninth embodiment will be described with reference to FIG. Also in this example, the source region and the drain region of the MOS transistor are formed by utilizing the impurity diffusion method according to the present invention. First, in step A, an element isolation region 212 made of a field oxide film is formed on the surface of the N-type Si substrate 211. A gate electrode 214 is formed in the center of the active region surrounded by the element isolation region 212 via a gate insulating film 213. Next, the gate electrode 214 is entirely covered with an oxide film, and then the oxide film is removed only from the upper surface of the gate electrode 214 to form sidewalls 215. The sidewalls 215 are used to form a so-called LDD structure. Next, the gate oxide film 2 on the surface of the silicon substrate to be the source and drain regions
Etch 13. Finally the vacuum chamber

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[Procedure amendment]

[Submission date] March 17, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a process chart showing a first embodiment of a method for manufacturing a semiconductor device according to the present invention.

FIG. 2 is a process chart showing an example of a conventional impurity diffusion method.

FIG. 3 is a graph showing the relationship between the background vacuum level and the variation in sheet resistance within the wafer.

FIG. 4 is a graph showing a relationship between a film forming temperature and a composition of a boron silicide film.

FIG. 5 is a rough view showing the relationship between the thickness of a boron silicide film and the sheet resistance of a boron diffusion layer.

FIG. 6 is a graph showing the relationship between the film thickness of a natural oxide film and the sheet resistance of a boron diffusion layer.

FIG. 7 is a schematic diagram showing a method for measuring the thickness of a boron silicide film.

FIG. 8 is a graph showing a depth direction impurity concentration profile of a boron diffusion layer.

FIG. 9 is a graph showing the chemical resistance of a boron silicide film.

FIG. 10 is a graph showing the chemical resistance of a boron film.

FIG. 11 is a second method of manufacturing a semiconductor device according to the present invention.
It is process drawing which shows an Example.

FIG. 12 is a third method of manufacturing a semiconductor device according to the present invention.
It is process drawing which shows an Example.

FIG. 13 is a fourth method for manufacturing a semiconductor device according to the present invention.
It is process drawing which shows an Example.

FIG. 14 is a fifth method of manufacturing a semiconductor device according to the present invention.
It is process drawing which shows an Example.

FIG. 15 is a graph showing a boron diffusion layer sheet resistance and variations in the wafer with respect to a high temperature processing time before diffusion.

FIG. 16 is a graph showing a boron diffusion layer sheet resistance and its variation within a wafer with respect to a high temperature processing time after diffusion.

FIG. 17 is a micrograph showing a surface state after annealing a boron silicide film.

FIG. 18 is a schematic view showing a removal process of a boron silicaide film.

FIG. 19 is a graph showing the film thickness of the boron silicon film and the diffusion layer sheet resistance after diffusion with respect to the oxidizing condition of the boron silicon film.

FIG. 20 is a seventh method of manufacturing a semiconductor device according to the present invention.
It is a schematic diagram which shows an Example.

FIG. 21 is a graph showing the diffusion capability of boron with respect to a silicon nitride film.

FIG. 22 is a graph showing the diffusion capability of boron with respect to a silicon oxide film.

FIG. 23 is a schematic diagram for explaining the degree of variation in sheet resistance of a boron diffusion layer depending on the presence or absence of a cap film.

FIG. 24 is a sixth method of manufacturing a semiconductor device according to the present invention.
It is process drawing which shows an Example.

FIG. 25 is an eighth method of manufacturing a semiconductor device according to the present invention.
It is process drawing which shows an Example.

FIG. 26 is a ninth method of manufacturing a semiconductor device according to the present invention.
It is process drawing which shows an Example.

FIG. 27 is a block diagram showing a method for evaluating a film thickness of an impurity film, which is a method for evaluating a semiconductor device according to the present invention.

FIG. 28 is a sectional view of an evaluation sample for explaining the method of evaluating the film thickness of an impurity film of the present invention.

29 is a graph showing the film thickness with respect to the gas introduction time, which is obtained by the film thickness evaluation method shown in FIG. 28.

FIG. 30 is a graph showing the correlation between the film thickness obtained by the optical film thickness evaluation method of the present invention and the film thickness obtained by mechanical means.

FIG. 31 is a block diagram of a semiconductor manufacturing apparatus of the present invention.

FIG. 32 is a graph showing a relationship between a boron film thickness measurement setting value and a B ₂ H ₆ gas introduction time, and a graph showing a change in B ₂ H ₆ gas pressure with respect to the boron film thickness (b).
Is.

FIG. 33 is a flowchart showing steps of the impurity doping method of the present invention.

FIG. 34 is a structural cross-sectional view of a MISFET having a boron silicide film on the surface of a source / drain region which is a semiconductor device of the present invention.

FIG. 35 is a MISF having a boron silicide film on the surface of the source / drain and gate electrodes of the semiconductor device of the present invention.
It is a structure sectional view of ET.

FIG. 36 is a structural cross-sectional view of an NPN bipolar transistor having a boron silicide film in a part of a base region which is another semiconductor device of the present invention.

FIG. 37 is a structural cross-sectional view of a PNP bipolar transistor having a boron silicide film on an emitter region which is still another semiconductor device of the present invention.

FIG. 38 is a structural cross-sectional view of a contact in which tungsten silicide and a semiconductor region are connected via a boron silicide film.

FIG. 39 is a structural cross-sectional view of a contact in which tungsten and a semiconductor region are connected via a boron silicide film.

FIG. 40 is a structural cross-sectional view of a contact in which a metal wiring having a barrier metal and a semiconductor region are connected via a boron silicide film.

[Explanation of reference numerals] 1,501 Silicon substrate 2 Boron silicide film 3 Boron diffusion region 502 Oxide film 503 Impurity film 511 Light source 512, 513 Optical system 514 Photodetector 531 High vacuum chamber 610 Insulating film spacer 611 N-type semiconductor region 612 P Type semiconductor region 613 boron silicide region 614 N type polysilicon gate 615 interlayer insulating film 616 metal wiring 620 insulating film spacer 621 N type semiconductor region 622 P type semiconductor region 623 boron silicide region 624 P type polysilicon gate 625 interlayer insulating film 626 metal Wiring 631 N-type collector region 632 N-type epitaxial region 633 P-type base region 634 Boron silicide region 635 N-type emitter region 630 CVD insulating film 641 P-type collector region 642 P-type Pitaxial region 643 N-type base region 644 P-type emitter region 645 Boron silicide region 646 CVD insulating film 651 P-type semiconductor region 652 Interlayer insulating film 653 Boron silicide region 654 Semiconductor film 655 Tungsten silicide film 661 P-type semiconductor region 662 Interlayer insulating film 664 Tanstain region 671 P-type semiconductor region 672 Interlayer insulating film 673 Boron silicide region 674 Titanium film 675 Titanium nitride film 676 Metal wiring

Continuation of the front page (31) Priority claim number Japanese Patent Application No. 5-60521 (32) Priority Day 5 (1993) March 19 (33) Country of priority claim Japan (JP) (72) Inventor Yoshikazu Kojima Tokyo 6-31-1 Kameido, Koto-ku, Seiko Electronics Industry Co., Ltd.

Claims (9)

[Claims] 1. After the cleaning step for exposing the active surface of the silicon layer, a gas containing a semiconductor impurity element is supplied to the active surface and the silicon layer is removed.
A method for manufacturing a semiconductor device, comprising: forming an impurity film composed of a semiconductor impurity element of 80 atomic% or more and a silicon element of 5 atomic% or more on the active surface by heating to a temperature higher than 600 ° C. 2. A cleaning step for exposing an active surface of a silicon layer, a treatment step for forming a compound layer of a semiconductor impurity element and silicon on the active surface, and a semiconductor impurity from the compound layer. A method of manufacturing a semiconductor device, comprising a diffusion step for introducing an element into a silicon layer. 3. The depositing step of forming a deposit layer containing a semiconductor impurity element on the active surface of the silicon layer, and the step of thermally reacting the deposit layer and the silicon layer 3. The method of manufacturing a semiconductor device according to claim 2, further comprising a heat treatment step of forming a compound layer of 4. A cleaning process for exposing an active surface of a silicon layer, and a treatment for forming one of a semiconductor impurity element film or a compound film of a semiconductor impurity element and silicon on the active surface. A method of manufacturing a semiconductor device, comprising a step and a film thickness evaluation step of measuring the film thickness of the impurity film by an optical means. 5. An incident light beam having a first polarization characteristic is obliquely incident on the surface of a silicon substrate on which only one of a semiconductor impurity element film that is an impurity film or a compound film of a semiconductor impurity element and silicon is formed on the surface. The step of irradiating the first step with the second polarization characteristic, the step of detecting a reflected light ray having a second polarization characteristic which is a reflected ray of the incident light ray, the first polarization characteristic and the second
The method for evaluating a semiconductor device is characterized in that the film thickness of the impurity film is obtained from the polarization characteristics of the above and the refractive index of the impurity film. 6. A high vacuum chamber for forming an impurity film on a semiconductor inside, and a high vacuum chamber provided on a wall of the high vacuum chamber for passing incident light and reflected light for evaluating a film thickness of the impurity film. A transparent window, a light source provided outside the high vacuum chamber to supply the incident light, and a photodetector provided outside the high vacuum chamber to detect the reflected light. A semiconductor manufacturing apparatus comprising: 7. The semiconductor manufacturing apparatus according to claim 6, wherein the pressure of the impurity film forming gas supplied into the high vacuum chamber is feedback-controlled by the output of the photodetector. 8. A first region of a semiconductor having an impurity diffused therein and a second region containing at least a compound of a semiconductor impurity element and silicon, wherein the first and second regions form a laminated structure. Semiconductor device. 9. The semiconductor device according to claim 1, wherein the second region has a laminated structure of the compound and a refractory metal.