JPH05211134A - Forming method of thin film and forming equipment of thin film - Google Patents

Abstract

PURPOSE:To form as Ti film or a TiN film at a low temperature about 500 deg.C, and form stable contact, by continuously performing a process for forming the Ti film or the TiN film in plasma generation, changing gas species and/or gas flow rate, and forming a thin film on a substrate. CONSTITUTION:In a magnetic field plasma CVD method, TiCl4, H2 or TiCl4, H2, and Ar gas are used, the substrate temperature is set to be lower than or equal to 500 deg.C, and a Ti film is formed on a substrate. After the Ti film is formed, TiCl4, H2, N2 or TICl4, H2, N2, and Ar gas are used, the flow rate ratio of N2 to TiCl4 is set to be higher than 0.5, and a TiN film is formed on a substrate. In the magnetic field plasma CVD method, TiCl4, H2, N2 or TICl4, H2, N2, and Ar gas are used, the flow rate ratio of N2 to TiCl4 is set to be lower than or equal to 0.5, and film formation is performed at the substrate temperature lower than or equal to 500 deg.C, thereby forming a TiN film rich in Ti on the substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film forming method and a thin film forming apparatus, and more particularly to a method for forming a barrier metal thin film and a thin film forming apparatus.

[0002]

2. Description of the Related Art A contact portion of an LSI has a diffusion layer on the surface of the substrate as a base and is connected to a wiring such as Al through a contact hole.

However, as the miniaturization and higher integration of LSI progress, the diffusion layer also becomes shallower, Al spikes occur in this shallow diffusion layer to break the junction, or Si deposits on the bottom of the contact hole to increase the contact resistance. Problems such as are occurring.

In order to solve these problems, Al alloy in which about 0.5 to 2% of Si is mixed in advance in Al (Al-
1% Si, etc.) has been used as an electrode wiring material, but recently the contact hole diameter has become smaller, and even these Al alloys have become insufficient to prevent the precipitation of Si.

Therefore, it has been considered to form a diffusion preventing thin film called a barrier metal between the Al alloy and the Si substrate. The TiN film is attracting attention as a barrier metal because it has low electric resistance and is chemically stable (Sansai, Yoshiwara, Kitahara, Hosokawa; “Vacuum” (JAPAN), Volume 30, No. 5, p3.
47, 1987).

Basically, p ⁺ Si is used as a barrier metal material.
And it is desirable to have a small barrier height to both n ⁺ Si. However, as shown in Table 1 below, T
The iN film has a high contact resistance with the Si diffusion layer (especially p ⁺ Si
However, it is necessary to form a base film of Ti or the like.

[0007]

[Table 1]

The formation of the Ti film is usually performed by the sputtering method using a Ti target.

CVD method (thermal CVD method, plasma CVD
There are almost no reports of Ti film formation by the method).

Also (Narumi; "Titanium Zirconium", vol24, No3, July 1976, p130-
p144) describes the formation of Ti using plasma. This is to reduce Ti halide (TiCl ₄ ) to titanium with a reducing agent such as hydrogen using an arc plasma jet, and it is necessary to supply the raw material into a 2000 ° C plasma jet torch. Furthermore, argon hydrogen plasma was used for the reduction of TiCl ₄ (Krapu
Khin and Korolev, 1968), ignitable fine titanium powder may be obtained, but it is not executed.

[0011]

As described above, the TiN film is effective as a barrier metal material for LSI. However, since the TiN film has a large contact resistance value with the Si diffusion layer, it was necessary to form a base film of Ti or the like.

As described above, the Ti film is usually formed by the sputtering method. However, the Ti film formed by the sputtering method has poor step coverage (step coverage), and the contact hole is miniaturized so that the aspect ratio is small. When the size becomes larger, there is a problem that the film is hardly formed on the bottom of the contact hole and cannot be used for a miniaturized LSI.

The LPCVD method (Low Pressure Chemi
The film formation by cal vapor deposition) generally has good step coverage, and the TiN film has been studied by forming it by the LPCVD method. However, Ti film formation requires high energy for the reduction of TiCl ₄ ,
The Ti film could not be formed by the LPCVD method in which the reaction is promoted by thermal energy.

Further, the formation of Ti by the arc plasma jet is a high temperature treatment exceeding 2000 ° C., and it is impossible to incorporate such a high temperature treatment into the LSI manufacturing process, and only Ti powder is obtained. There was a problem that not.

The present invention has been invented in view of the above-mentioned problems, and enables formation of a Ti film or a Ti-rich TiN film at a low temperature applicable to the manufacturing process of LSI.
A contact with low contact resistance and high barrier property is realized by combining with the film forming process.
Furthermore, by incorporating a pretreatment process and a heat treatment process, it is an object of the present invention to perform stable contact formation with a lower contact resistance with good yield and reproducibility.

[0016]

In order to achieve the above object, a method of forming a thin film according to the present invention comprises a magnetic field plasma CV.
In the D method, TiCl ₄ and H ₂ or TiCl ₄ and H ₂ and Ar gas are used to form a Ti film on the substrate (1), and in the magnetic field plasma CVD method, TiCl _{4 is used.}
And using H ₂ and N _2, or TiCl ₄ and H _2, N _2, and Ar gas, N ₂
It is characterized in that a Ti-rich TiN film (χ> y in TixNy) is formed on the substrate by setting the flow rate ratio of TiCl ₄ to 0.5 or less (2).

Further, in the method of forming a thin film described in (1) or (2) above, a Ti film or a Ti-rich TiN film is formed at a substrate temperature of 500 ° C. or lower (3).

A Ti film is formed by using the method described in (1) above, and then TiC is formed by a magnetic field plasma CVD method.
L ₄ and H ₂ and N ₂ or TiCl ₄ and H ₂ and N ₂ and Ar gas are used,
The flow rate ratio of TiCl ₄ N ₂ on the substrate as a 0.5 or higher
A TiN film is formed (4), and a Ti-rich TiN film is formed using the method described in (2) above.
After that, TiCl ₄ and H ₂
Using N ₂ or TiCl ₄ , H ₂ , N ₂ and Ar gas, N ₂ TiC
A TiN film is formed on the substrate at a flow rate ratio of 0.5 or more with respect to l ₄ (5), and a Ti film or a Ti-rich TiN film is formed using the method described in (3) above. After that, TiCl ₄ and
Using H ₂ and N ₂ or TiCl ₄ H ₂ and N ₂ and Ar gas, the N ₂
TiN on the substrate with a flow rate ratio of 0.5 or more to TiCl ₄
It is characterized by forming a film (6).

Further, in the thin film forming method described in (4) above, the step of forming a Ti film and the step of forming a TiN film are continuously performed by changing the gas species and / or the gas flow rate. In the method for forming a thin film described in (7) above, which is characterized in that a two-layer film is continuously formed on the substrate.
The step of forming a film and the step of forming a TiN film are performed during continuous plasma generation by changing the gas species and / or the gas flow rate to form a two-layer film continuously on the substrate. In the thin film forming method described in (8) and (6) above, the step of forming a Ti film or a Ti-rich TiN film and the step of forming a TiN film are performed by changing the gas species and / or the gas flow rate. It is characterized in that a two-layer film is continuously formed on the substrate by changing the temperature to continuously generate plasma (9).

Further, in the method for forming a thin film described in (4) above, a Ti film is formed on a substrate in one chamber, and then the substrate is transferred to another chamber in a vacuum, In the method for forming a thin film described in (5) above, a TiN film is formed on the substrate by the method described in (5) above.
The method is characterized in that a Ti-rich TiN film is formed, then the substrate is transferred to another chamber in vacuum, and the TiN film is formed on the substrate in the another chamber (11), and above (6). ) In the method for forming a thin film described above, a Ti film or a Ti-rich TiN film is formed on a substrate in one chamber, and then the substrate is transferred to another chamber in a vacuum, It is characterized by forming a TiN film on the substrate (12).

Further, using the method described in (3) above, Ti
A film or a Ti-rich TiN film is formed, and then the substrate is subjected to heat treatment at 500 ° C. or higher (1
3) Further, in the method for forming a thin film according to (10) or (11) above, a Ti film or a Ti-rich TiN film is formed at a substrate temperature of 500 ° C. or lower, and then the substrate is vacuumed into another chamber. During the transportation, 5
Characterized by adding a heat treatment of at least 00 ° C. (14),
Further, the above (4), (5), (7), (8), (10)
Alternatively, a Ti film or a Ti film is formed on the substrate by the method described in (11).
A Ti-rich TiN film and a TiN film are formed at a temperature of 500 ° C. or lower, and then the substrate is transferred to a heating furnace in vacuum, and heat treatment is performed at 500 ° C. or higher in the heating furnace. (15).

Furthermore, in the thin film forming apparatus used in the method for forming a thin film described in the above (10) or (11), a chamber for forming a Ti film or a Ti-rich TiN film on a substrate, and a substrate It is characterized by further comprising a chamber for forming a TiN film thereon and a vacuum transfer path for transferring between these chambers in a vacuum (1
6).

Further, in the method of forming a thin film as described in any of (1) to (15) above, plasma cleaning is performed before forming a Ti film or a Ti-rich TiN film (17), Further, in the thin film forming method described in (17) above, plasma cleaning is performed in a chamber for forming a Ti film or a Ti-rich TiN film (18), and the thin film formation according to (17) above is performed. The forming method is characterized by comprising a plasma cleaning chamber, a chamber for forming a Ti film or a Ti-rich TiN film, and a vacuum transfer path for transferring these chambers in a vacuum (1
9).

Furthermore, in the method of forming a thin film according to any one of (1) to (15) above, a Ti film and a Ti-rich
Prior to forming either the TiN film or the TiN film, the substrate is irradiated with H ₂ plasma or H ₂ and Ar plasma (20), and the method for forming a thin film according to (20) above, Irradiation of H ₂ plasma or H ₂ and Ar plasma onto the substrate and formation of either Ti film, Ti-rich TiN film or TiN film are performed continuously by changing the gas species and / or gas flow rate. It is characterized in that it is performed during generation (21).

[0025]

[Function] The following reaction formula can be considered as a reaction mechanism of Ti film formation.

TiCl ₄ + 2H ₂ → Ti + 4HCl However, in order to completely decompose TiCl ₄ into Ti and Cl, very high energy of 400 kcal mol ⁻¹ or more is required as required from FIG.

Therefore, very high energy is required in order to advance the above reduction reaction. The method using the arc plasma jet shown in the prior art makes this possible by performing the treatment in thermal plasma at 2000 ° C. or higher.

On the other hand, in the method according to the present invention, attention is paid to the use of non-equilibrium plasma (the electron temperature, the ion temperature, the gas temperature, etc. are different) under reduced pressure.
In a plasma using a resonance phenomenon such as CR plasma, it is noted that high-energy electrons are generated in the plasma. That is, in plasma under reduced pressure, especially in plasma utilizing a resonance phenomenon, high-energy electrons are present, and the decomposition / reduction reaction is promoted by collision of these high-energy electrons. Therefore, the Ti film is formed without raising the substrate temperature to a high temperature such as 2000 ° C., and the formed Ti is not a powder but a film.

In particular, when the film is formed by using ECR plasma, since ECR plasma is a plasma having a good directivity, there is an advantage that a film can be formed with good step coverage even for a fine contact hole.

Further, in the method of the present invention, TiN film and Ti
When forming a rich TiN film (Ti _x N _y , χ> y) using TiCl ₄ , H ₂ , N ₂ and Ar gas, the flow rate ratio of N _{2 to} TiCl _{4 is set} to 0.5 or more. A Ti-rich TiN film can be formed by setting the film to 0.5 or less. Further, by utilizing this fact, the Ti film or the Ti-rich TiN film and the TiN film can be continuously formed by changing the gas species and / or the gas flow rate.

In the method of the present invention, the Ti film or the Ti-rich TiN film and the TiN film are formed in different chambers, so that the Ti film or the Ti-rich TiN film and the TiN film are formed in one chamber. Unlike the case where film formation is repeated, it is possible to prevent Ti film or Ti-rich TiN film and TiN film from alternately depositing on the inner wall of the chamber and peeling off to generate particles. ..

When a Ti film or a Ti-rich TiN film is formed on a silicon substrate at a substrate temperature of 500 ° C. or higher, Ti
Since the silicidation proceeds at the interface between the film or the Ti-rich TiN film and silicon, the silicidation progresses at the same time as the film formation, but the distribution of the substrate temperature during plasma generation is affected by plasma irradiation and is slightly non-uniform. Therefore, the silicidation proceeds nonuniformly. Therefore, in the method of the present invention, a Ti film or a Ti-rich TiN film is formed on a silicon substrate, and heat treatment is performed to reduce the resistance of the contact (TiSi ₂ is formed at the interface with silicon). The film is formed at a temperature of 500 ℃ or less, and then heat treatment is performed at 500 ℃ or more in the absence of plasma in a uniform temperature distribution to promote uniform silicidation, enabling stable low resistance contact formation. To do. The heat treatment may be performed before or after the TiN film is formed.

In carrying out the method of the present invention, it is not preferable to expose the substrate to the atmosphere after the Ti film or the Ti-rich TiN film is formed and before the TiN film is formed. This is because Ti is an active metal and is oxidized immediately when exposed to the atmosphere.

Further, in the method of the present invention, Ti on the substrate is
Before the film or Ti-rich TiN film is formed, the substrate is cleaned (mainly the natural oxide film on the substrate is removed), that is, plasma cleaning is performed using a gas containing CF ₄ , etc. Enables cleaning of fine contact holes, which was a problem.

When forming a film using TiCl ₄ gas, Ti
Since Cl ₄ gas has a low vapor pressure and high adsorptivity, TiCl ₄ gas is adsorbed on the substrate surface, a layer containing a large amount of chlorine is formed at the interface portion, and then plasma is generated to strike the substrate surface. Even if activated by the above, with respect to the problem that the layer containing chlorine adsorbed on the surface cannot be easily peeled off, in the method of the present invention, H ₂ plasma or H ₂ and Ar plasma are previously introduced before introducing TiCl ₄ gas. By irradiating the substrate, the surface of the substrate is activated to prevent TiCl ₄ gas from adsorbing to the surface of the substrate and to prevent generation of a chlorine adsorption layer.

Further, the addition of Ar gas in the method of the present invention has the effects of strengthening and stabilizing the plasma intensity and increasing the film formation rate and the like.

[0037]

Embodiments of a thin film forming method and a thin film forming apparatus according to the present invention will be described below with reference to the drawings.

In this embodiment, Ti is formed by using the plasma CVD method.
The case where a film or a Ti-rich thin film is formed on a substrate will be described in detail.

FIG. 2 is a sectional view schematically showing a plasma CVD apparatus used in the method of forming a thin film according to this embodiment.

The plasma CVD apparatus comprises an apparatus body 3 consisting of a plasma generation chamber 1 and a reaction chamber 2, and an exciting coil 4 arranged around the plasma generation chamber 1 and connected to a DC power source (not shown). And a waveguide 5 for introducing microwaves oscillated from a microwave oscillator (not shown) into the plasma generation chamber 1. Reference numeral 6 is a microwave introduction window formed of quartz glass or the like, 7 is a high frequency generation source for applying a high frequency (RF) power source to the microwave introduction window, and 8 is a sample table on which the substrate 9 is placed. ..

The plasma generating chamber 1 is formed in a substantially cylindrical shape, and a first hole 10 for introducing a microwave is formed in a substantially central portion of an upper wall of the plasma generating chamber 1. A reaction chamber 2 having a larger diameter than the plasma generation chamber 1 is integrally formed below the plasma generation chamber 1. Further, the reaction chamber 2 and the plasma generation chamber 1 are partitioned by a partition plate 11, and a second hole (plasma extraction window) 12 is formed at a substantially central portion of the partition plate 11.

Further, a first introduction pipe 13 is connected to the side wall of the reaction chamber 2, and an exhaust pipe 14 communicating with an exhaust system (not shown) is connected to the bottom of the reaction chamber 2. Further, the second introduction pipe 15 is provided on the upper wall of the plasma generation chamber 1.
Are connected.

The high frequency generator 7 comprises a high frequency generator 16 and a matching box 17, and a microwave introducing window 6 is interposed via a plate electrode 18 sandwiched between the microwave introducing window 6 and the waveguide 5. A high frequency is applied to.

An RF high frequency oscillator 21 for applying an RF high frequency to the substrate 9 is connected to the sample stage 8 via a matching box 20. This RF high frequency oscillator 2
By applying a predetermined RF high frequency to the substrate 9 by the method 1 and performing the above-described thin film forming method, the bias voltage applied to the substrate 9 allows good step coverage even when the uneven surface of the substrate 9 is finer. A thin film can be formed.

Further, the substrate 9 is heated by a predetermined heater or the like,
If the temperature of the substrate 9 is kept at a predetermined value of 500 ° C. or lower, a thin film can be formed without causing a silicidation reaction with the base.

The plasma CVD apparatus is constructed so that a predetermined magnetic field is generated in the plasma generating chamber 1 when DC power is supplied to the exciting coil 4. As a result, a magnetic field is formed so that the angular frequency ω of the microwave introduced from the microwave oscillator into the plasma generation chamber 1 and the angular frequency ω _{c of the} electron cyclotron become equal in the plasma generation chamber 1, and the electrons have resonance motion. It can also be configured to wake up. The condition for causing this resonance, that is, the ECR condition can be easily obtained by solving the classical mechanical equation and is represented by the following equation.

Ω = ω _c = eB / m ... where e is the electron charge (= 1.6 × 10 ^-19 C), B is the magnetic flux density (T), and m is the electron mass (= 9.1 × 10). ^-31 kg) respectively.

In this embodiment, the angular frequency ω of the microwave is
It is set to 2.45 GHz, and the magnetic flux density B satisfying the ECR condition from the above equation is 8.75 × 10 ^-2 T.

In order to form a thin film using the above apparatus, first, the exhaust system is operated to reduce the pressure in the apparatus main body 3 to a pressure of 1 × 10 ^-6 Torr or less, and then TiCl ₄ 10 SCCM is used for the first step. While supplying from the introduction pipe 13 into the reaction chamber 2, Ar43SCCM,
H ₂ 50 SCCM in plasma generation chamber 1 2nd introduction pipe 1
Supply from 5. After that, the inside of the apparatus main body 3 is set to a predetermined pressure, for example, 2 × 10 ⁻³ Torr.

Further, the high frequency generator 7 is energized to apply a voltage to the microwave introduction window 6 to prevent the Ti thin film from adhering to the microwave introduction window 6 due to the sputtering effect of Ar ions by the high frequency.

On the other hand, a microwave having an output of 2.8 KW is introduced from the microwave oscillator into the plasma generation chamber 1 through the waveguide 5, and a DC power source is connected to the exciting coil 4 to generate a magnetic field in the plasma generation chamber 1. Give rise to. Then, high-energy electrons collide with the raw material gas in the plasma generation chamber 1, and the raw material gas is decomposed and ionized to generate plasma.

Next, this plasma passes through the second hole 12, is accelerated by the divergent magnetic field in the direction of the arrow A in the figure, is guided into the reaction chamber 2, and is directed to the surface of the substrate 9 mounted on the sample stage 8.
A Ti film or a Ti-rich TiN thin film is formed. afterwards,
Furthermore, N ₂ gas is added from the introduction pipe 15 at a flow rate of 15 SCCM to continuously form a film, thereby TiN (1000 Å) / Ti
A two-layer film of (300Å) / Si substrate was formed. The result is shown in Figure 3.
Shown in. Fig. 3 shows the results of analysis by Auger electron spectroscopy, showing the relationship between the sputtering time from the surface and the intensity of each element, a Ti film on a Si substrate, and TiN on it.
It is recognized that a film is formed. Further, in this example, since the film was formed at 460 ° C., it can be seen that the silicidation reaction is suppressed in the Ti film layer.

Further, the substrate temperature was variously changed, and the film was formed on the Si substrate and the quartz glass substrate, the film thickness was measured by an SEM (scanning electron microscope), and the film formation rate (Å / min) was measured. I investigated the relationship. The result is shown in FIG.

In FIG. 4, when the substrate temperature is 500 ° C. or higher,
It can be seen that the thickness of the deposited film on the Si substrate is significantly thicker than that on the quartz glass plate. This indicates that the deposited Ti film reacts with Si of the substrate to form a Ti silicide film having a large lattice constant. That is, the thickness of the deposited film is apparently increased.

From this, it is understood that when the substrate temperature is raised to 500 ° C. or higher, the formed Ti film or Ti-rich film reacts with the underlying substrate Si to form a silicide.

Further, an actual LSI device was manufactured. However, if the film forming temperature is up to 1000 ° C., the device, especially the diffusion layer is not adversely affected, the Ti film can be silicidized, and the low resistance contact can be formed. Could be realized.

Further, a Ti film is formed at contact holes of various diameters at a film forming temperature of 460 ° C., and thereafter RTP (Rapid Thermal Process) is performed under the optimum conditions shown in Table 2 described later.
A treatment was performed to form a silicide, and the contact resistance value was examined. The result is shown in FIG. For comparison, a Ti film and a TiN film were formed on the contact portion by the sputtering method, and the RT
The contact resistance value was examined by forming a silicide by P treatment. The results are also shown in FIG. The n-channel one was used as the diffusion layer of the underlying Si substrate.

As is apparent from FIG. 5, the ECR plasma CVD method was able to realize a low resistance contact which was completely the same as that of the sputtering method.

When N ₂ is added during formation of the Ti film, TiN
A film could be formed. The result is shown in FIG.
When the flow rate of N ₂ is gradually increased from 0, Ti film or Ti film
Approaching from the rich TiN film to the TiN film. And Ti
When the flow rate of Cl ₄ is 10 SCCM and the flow rate of N ₂ is 5 SCCM or more, the TiN composition does not change at about 1: 1. Therefore, when the flow rate of N ₂ with respect to TiCl ₄ is 0.5 or less, Ti
It can be seen that the Ti-rich TiN film can be continuously formed from the Ti film by increasing the N ₂ flow rate with respect to the Cl ₄ flow rate.

Ti-rich Ti formed by such a method
The N film (a film having a Ti ratio higher than the stoichiometric composition of Ti: N = 1: 1) has the same effect as the Ti film and should be used sufficiently as a barrier layer to replace the Ti film. You can

Since Ti is an active metal and is oxidized immediately when exposed to the atmosphere, the TiN film is continuously formed in the chamber where the Ti film is formed, or after the Ti film is formed. It is necessary to vacuum-transfer to the TiN film forming chamber and to form a TiN film for stable contact formation. After the Ti film or the Ti-rich TiN film was formed, if the TiN film was formed without exposing it to the atmosphere as described above, the surface of the Ti film was not oxidized and stable contact formation was possible.

FIG. 11 shows a configuration diagram (plan view) of an apparatus for forming a Ti film and a TiN film in different chambers. The cassette stage 40 is a table on which an unprocessed Si substrate is placed. The Si substrate set on the cassette stage 40 is transferred to the orientation flat alignment mechanism 4 by the transfer robot 42a.
It is moved to 1 and the orifla is combined. After that, the robot 42a again conveys it to the loading chamber 43. After evacuating the loading chamber 43, the robot 4
2b is transferred to the Ti film forming plasma CVD chamber 45 through the transfer chamber 44 and a Ti film is formed. After that, again via the transfer room 44, TiN
It is transported to the film forming plasma CVD chamber 46, where
A TiN film is formed.

Here, the transfer chamber 44, the plasma CVD chamber 45, and the plasma CVD chamber 46 are
Since the structure is such that all can be evacuated, after the Ti film is formed in the plasma CVD chamber 45, the plasma C
The Si substrate is not exposed to the atmosphere until the TiN film is formed in the VD chamber 46. After the TiN film is formed in the plasma CVD chamber 46, the TiN film is transferred to the loading chamber 47 via the transfer chamber 44 and returned to the atmosphere here. Further, the robot 42 transfers the robot to the cassette stage 48 to complete the treatment.

The silicidation of the Ti film is 500 to 1000
The film forming temperature of ° C occurs at the same time as the formation of the Ti film, but if the film forming temperature is 500 ° C or less, a subsequent heat treatment step is required. An RTP device can be used for this heat treatment, and by incorporating this RTP device into a multi-chamber, it was possible to prevent the oxidation of the Ti film and contribute to stable contact formation. Even if the RTP process is performed between the formation of the Ti film and the formation of the TiN film, the Ti film and T
Good results were obtained even after forming the iN film. It was confirmed that the silicidation reaction proceeds at a heat treatment temperature of 500 ° C. or higher. Table 2 shows the optimum conditions of the RTP treatment, and FIG. 9 shows the change of the Si substrate temperature at that time.

[0065]

[Table 2]

In order to form a stable contact
Although the native oxide film on the Si substrate was removed by wet cleaning before forming the Ti film, the reproducibility was poor due to large variations in contact resistance within the wafer. It is considered that this is because the inside of the fine contact hole cannot be sufficiently cleaned. Therefore, when plasma cleaning was performed using CF ₄ gas before forming the Ti film, it was possible to realize a stable contact with little variation and high yield. Plasma cleaning may be performed in the Ti film forming chamber or in a dedicated cleaning chamber other than the Ti film forming chamber. However, when cleaning in the dedicated chamber, the Ti film forming chamber is used. It is necessary to vacuum transfer the Si substrate. Even if exposed to the atmosphere even once, the stability of the contact deteriorated.

As a plasma cleaning method, microwave plasma cleaning or ECR plasma cleaning was able to obtain good results (low resistance contact).

As the microwave plasma cleaning device, a SWP device (Surface Wave Produced Plasmas device) used as an ashing device was used, the plasma conditions were O ₂ : CF ₄ = 368: 52 SCCM, the pressure was 0.5 mTorr, and the micro The wave power was set to 1.5 kW, the substrate temperature was set to room temperature, and the treatment was performed for 2 minutes. (K. Komachi and
S. Kobayashi, J. Microwave Power and Electromagnetic
Energy, vol25, No4, 1990), (K.Komachi et al,
Extended Abstruct of the Electrochemical Soc., Fal
l Meeting, Seattle, October 14-19, 1990, p6
74-675).

The outline of the apparatus is shown in FIG. Reference numeral 30 denotes a cleaning chamber. A sample table 31 is arranged in the cleaning chamber 30, an exhaust port 32 is connected to a lower portion of the cleaning chamber 30, and a plasma chamber 33 is formed above the cleaning chamber 30. .. Above the plasma chamber 33, an alumina plate 34, a Teflon sheet 35, and an aluminum plate 36 are further provided.
Etc. are arranged.

FIG. 12 is a structural view (plan view) of an apparatus in which the plasma cleaning chamber is provided separately from the chamber for forming the Ti film and the TiN film. Except that the plasma CVD chamber is changed to the cleaning chamber 55, the device configuration may be considered to be almost the same as the device of FIG. Here, as the cleaning chamber 55, the SWP device shown in FIG. 10 is used.

The transfer chamber 54, the cleaning chamber 55, and the ECR plasma CVD chamber 56 are all constructed so that they can be evacuated. Therefore, the Si substrate cleaned in the cleaning chamber 55 is transferred to the transfer chamber 54 without being exposed to the atmosphere.
And then transferred to the ECR plasma CVD chamber 56
A Ti film and a TiN film are formed.

It is also effective to form a Ti-rich TiN film instead of the Ti film as described above.

The effect of irradiating the substrate 9 with H ₂ and Ar plasma before introducing TiCl ₄ gas when depositing a Ti film and a TiN film using the apparatus shown in FIG. 2 will be described. .. FIG. 7 (a) shows that H ₂ and A are applied to the substrate 9 in advance.
r After plasma irradiation, TiCl ₄ gas is introduced,
SIMS (Secondar
y Ion Microscopy).
(B) is TiCl ₂ without irradiation of H ₂ and Ar plasma on the substrate 9.
₄ is introduced, and the interface portion of the substrate 9 on which the Ti film is formed is measured by SIMS. More specifically, regarding the substrate 9 of FIG. 7A, first, H ₂ gas of 50 sccm and
Ar gas 43sccm is introduced into the plasma generation chamber 1, plasma is generated with microwave power of 2.8kW, and then TiCl ₄ gas 10sccm, N ₂ gas 15sccm, H ₂ gas 50sccm and Ar gas 43sccm are reacted with the plasma generation chamber 1 and the reaction. Supply to chamber 2
A Ti film is formed. From this result, it is understood that the one not subjected to the plasma pretreatment has a chlorine adsorption layer at the interface between Si and Ti, and the chlorine adsorption layer can be removed by the plasma pretreatment.

Regarding the pretreatment at the time of forming the TiN film,
The measurement results by SIMS are shown in FIGS. 8 (a) and 8 (b). As for the substrate 9 in FIG. 8A, first, H ₂ gas is 50 sccm.
And 43 sccm of Ar gas were introduced into the plasma generation chamber to generate plasma with microwave power of 2.8 kW, and then TiCl
₄ gas 10sccm, N ₂ gas 15sccm, H ₂ gas 50sccm and
A TiN film is formed by supplying Ar gas of 43 sccm. From this result, it is understood that the one not subjected to the plasma pretreatment has a chlorine adsorption layer at the interface between Si and TiN, and the chlorine adsorption layer can be removed by performing the plasma pretreatment. Further, in this measurement, the pretreatment and the film formation were performed in continuous plasma, but it was effective even if this was performed stepwise. Also, the pretreatment plasma is
The effect was seen only with H ₂ plasma.

[0075]

As is apparent from the above description, according to the thin film forming method and the thin film forming apparatus of the present invention, 50
A Ti film or a Ti-rich film can be formed at the contact portion at a low temperature of about 0 ° C., and stable contact formation can be performed by combining with a TiN film forming process. Further, by incorporating a cleaning process and a heat treatment process, the yield and reproducibility of contact formation can be further improved.

[Brief description of drawings]

FIG. 1 is an energy level phase diagram in a TiCl ₄ —N ₂ system.

FIG. 2 is a schematic sectional view showing an example of a plasma CVD apparatus.

FIG. 3 is a chart showing the analysis result in the depth direction by Auger electron spectroscopy.

FIG. 4 is a graph showing the substrate temperature dependence of the film formation amount of a Ti-rich film on a SiO ₂ substrate and a Si substrate.

FIG. 5 is a graph showing the relationship between contact hole diameter and contact resistance.

FIG. 6 is a graph showing the film composition when the flow rate of N ₂ gas is changed.

FIG. 7 (a) is a SIMS in the depth direction of the Ti—Si interface when the pretreatment is performed and (b) is not performed.
It is a chart which shows a measurement result.

FIG. 8A is a SIMS in the depth direction of the Ti—Si interface in the case where the pretreatment is performed and in the case where the pretreatment is not performed.
It is a chart which shows a measurement result.

FIG. 9 is a graph showing a temperature change of a substrate during RTP processing.

FIG. 10 is a sectional perspective view showing a microwave plasma cleaning device.

FIG. 11 is a plan view of an apparatus for forming a Ti film and a TiN film in different plasma CVD chambers.

FIG. 12 is a plan view of an apparatus in which a plasma cleaning chamber is provided separately from the Ti film and TiN film forming chambers.

[Explanation of symbols]

 1 Plasma generation chamber 2 Reaction chamber 9 Sample

Claims (21)

[Claims] 1. TiCl ₄ in the magnetic field plasma CVD method
And H ₂ or TiCl ₄ and H ₂ and Ar gas are used to
A method for forming a thin film, which comprises forming a film. 2. TiCl ₄ in the magnetic field plasma CVD method
And using H ₂ and N _2, or TiCl ₄ and H _2, N _2, and Ar gas, N ₂
A method of forming a thin film, characterized in that a Ti-rich TiN film (χ> y in TixNy) is formed on a substrate by setting the flow rate ratio of TiCl ₄ to 0.5 or less. 3. A Ti film or a Ti film at a substrate temperature of 500 ° C. or lower.
The method for forming a thin film according to claim 1 or 2, wherein a rich TiN film is formed. 4. A Ti film is formed by using the method according to claim 1, and then TiCl ₄ is formed by a magnetic field plasma CVD method.
Using H ₂ and N ₂ or TiCl ₄ H ₂ and N ₂ and Ar gas, the N ₂
TiN on the substrate with a flow rate ratio of 0.5 or more to TiCl ₄
A method for forming a thin film, which comprises forming a film. 5. The method according to claim 2, wherein Ti-rich
A TiN film is formed, and then TiCl ₄ , H ₂ , N ₂ or TiCl ₄ , H ₂ , N ₂ , Ar gas are used by a magnetic field plasma CVD method, and the flow rate ratio of N ₂ to TiCl ₄ is 0. A method for forming a thin film, characterized in that a TiN film is formed on a substrate with a thickness of 5 or more. 6. A Ti film or a Ti-rich TiN film is formed by using the method according to claim 3, after which a magnetic field plasma C is formed.
According to the VD method, TiCl ₄ , H ₂ , N ₂ or TiCl ₄ , H ₂ , N ₂
And Ar gas are used, and the flow rate ratio of N ₂ to TiCl _{4 is set} to 0.
A method of forming a thin film, characterized in that a TiN film is formed on a substrate as 5 or more. 7. The step of forming a Ti film and the step of forming a TiN film are performed during continuous plasma generation by changing the gas species and / or the gas flow rate, and two layers are continuously formed on the substrate. The method for forming a thin film according to claim 4, wherein a film is formed. 8. A step of forming a Ti-rich TiN film, and T
The step of forming an iN film is performed during continuous plasma generation by changing the gas species and / or the gas flow rate, and a two-layer film is continuously formed on the substrate. Method for forming thin film. 9. A Ti film or a Ti-rich TiN film forming step and a TiN film forming step are performed in a continuous plasma generation by changing a gas species and / or a gas flow rate, 7. The method for forming a thin film according to claim 6, wherein a two-layer film is continuously formed on the film. 10. A Ti film is formed on a substrate in one chamber, and then the substrate is transferred to another chamber in vacuum to form a TiN film on the substrate in the another chamber. The method for forming a thin film according to claim 4, wherein the thin film is formed. 11. A Ti-rich TiN film is formed on a substrate in one chamber, and then the substrate is transferred to another chamber in vacuum to form a TiN film on the substrate in the another chamber. The method for forming a thin film according to claim 5, wherein: 12. A Ti film or a Ti-rich TiN film is formed on a substrate in one chamber, and then the substrate is transferred to another chamber in a vacuum, and TiN is formed on the substrate in the other chamber. The method for forming a thin film according to claim 6, wherein a film is formed. 13. A Ti film or a Ti-rich TiN film is formed by using the method according to claim 3, and then 50 is formed on the substrate.
A method for forming a thin film, which comprises applying a heat treatment at 0 ° C. or higher. 14. A Ti film or a Ti-rich TiN film is formed at a substrate temperature of 500 ° C. or lower, and then, while the substrate is transferred to another chamber in a vacuum, a 5% film is formed on the substrate.
A heat treatment at a temperature of 00 ° C. or higher is added.
0 or the method of forming a thin film according to claim 11. 15. A Ti film or a Ti-rich TiN film and a TiN film are formed on a substrate at a temperature of 500 ° C. or lower by the method according to claim 4, 5, 7, 8, 10 or 11. After that, the substrate is transferred to a heating furnace in a vacuum, and a heat treatment at 500 ° C. or higher is applied in the heating furnace to form a thin film. 16. A Ti film or Ti-rich TiN is formed on a substrate.
A chamber for forming the film and further TiN on the substrate
12. A thin film forming method used in the thin film forming method according to claim 10 or 11, further comprising a chamber for forming a film and a vacuum transfer path for transferring these chambers in vacuum. apparatus. 17. The plasma cleaning is performed before forming the Ti film or the Ti-rich TiN film.
The method for forming a thin film as described in any one of 1. 18. Plasma cleaning for a Ti film or
18. The method for forming a thin film according to claim 17, which is performed in a chamber for forming a Ti-rich TiN film. 19. A plasma cleaning chamber, a chamber for forming a Ti film or a Ti-rich TiN film, and a vacuum transfer path for transferring these chambers in vacuum. A thin film forming apparatus used in the method for forming a thin film described above. 20. H ₂ plasma or H ₂ and Ar before formation of any of Ti film, Ti-rich TiN film or TiN film.
The method for forming a thin film according to claim 1, wherein the substrate is irradiated with plasma. 21. Irradiation of a substrate with H ₂ plasma or H ₂ and Ar plasma, and a Ti film, a Ti-rich TiN film or TiN
21. The method for forming a thin film according to claim 20, wherein any one of the films is formed during continuous plasma generation by changing a gas species and / or a gas flow rate.