JPH05129452A - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a method for manufacturing a semiconductor device with a high yield. A contact hole 7 is formed in the first insulating films 5 and 6 on the main surface of the p-type silicon substrate 1, a tungsten film 8 is formed on this wafer, and a tungsten film 8 on at least the first insulating film 8 is formed. As ions 12 are injected into the inside, and at least the tungsten film 8 on the first insulating film is etched and removed. [Effect] Since the grains of the tungsten film are crushed by the ion implantation to form fine particles, the generation of residues when removing the tungsten film by etching is reduced, and a semiconductor device with a good yield can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly to improvement of a contact hole having a multi-layer wiring structure and connecting each wiring.

[0002]

2. Description of the Related Art As an example of a conventional contact hole having a multilayer wiring structure, a contact hole for connecting an aluminum wiring to an impurity diffusion layer or a polycrystalline silicon film wiring will be described. In recent years, with the miniaturization, the width of the contact hole has become smaller and the depth has become deeper. When the depth / width = aspect ratio, the aspect ratio becomes larger and larger, and aluminum cannot enter the contact hole. A method of filling with a polycrystalline silicon film or a tungsten film has been adopted. For example, in Japanese Patent Laid-Open No. 61-3404, a contact hole is opened, a polycrystalline silicon film is deposited, and then an excess portion of the polycrystalline silicon film is converted into an oxide by thermal oxidation and then removed to remove the contact. A method of filling the inside of the hole with a polycrystalline silicon film is shown. Further, as a method for filling a groove provided in a silicon substrate for element isolation, a method using an oxide and a polycrystalline silicon film is disclosed in JP-A-60-1546.
No. 38, which uses oxides of tungsten and molybdenum is disclosed in JP-A-60-158643.

9 to 16 are cross-sectional views showing, in the order of manufacturing steps, a conventional method of manufacturing a semiconductor device in which a contact hole is filled with a tungsten (W) film. Figure 9
1 is a P-type silicon substrate, 2 is a field oxide film formed on one main surface of the P-type silicon substrate 1, and 3 is an N formed on the P-type silicon substrate 1 by penetrating the field oxide film 2. ⁺ Impurity diffusion layer, 4 is a polycrystalline silicon film formed on the field oxide film 2 to be a gate electrode or wiring, 5 is a non-doped silicon oxide film formed on a wafer made of 1 to 4 by a CVD method, 6 Is a BPS formed on the non-doped silicon oxide film 5 by the CVD method.
It is a G film. Then, the BPSG film 6 is heat-treated for reflow, and then the contact hole 7 is formed by anisotropically dry-etching the BPSG film 6 and the non-doped silicon oxide film 5 using a resist (not shown) as a mask. The width of this contact hole 7 is 0.8μ
m, and the depth is about 1 μm. Next, as shown in FIG. 10, tungsten hexafluoride (WF6) gas and hydrogen (H
2) A tungsten film 8 having a film thickness of about 1 is formed by a CVD method in a vacuum state of about 10 Torr at a temperature of about 450 ° C. using a gas.
μm is deposited. At this time, the tungsten film 8 is partially turned into grains (coarse grains) depending on the temperature at the time of deposition, as shown in FIG. Grain can be observed with an electron microscope, and naturally the grain size is about 0.5 to 1 μm depending on the generation conditions. In particular, it grows greatly in the thickness direction. Thereafter, as shown in FIG. 11, the tungsten film 8 is plasma anisotropic dry-etched using sulfur hexafluoride (SF6) gas containing a small amount of oxygen to form the tungsten film 8 in the contact hole 7. To do. At this time, about 0.1 to 0.
The residue 9 of the fine tungsten film 8 of about 3 μm is BPS.
It occurs on the G film 6. Next, as shown in FIG. 12, an aluminum wiring 10 is formed by a sputtering method, and a tungsten film 8 is formed.
Connect with.

[0004]

Since the conventional semiconductor device is constructed and manufactured as described above, the upper layer aluminum wiring 10 is easily broken or short-circuited by the residue 9 of the tungsten film 8. Further, depending on the conditions for forming the tungsten film 8, the inside of the contact hole 7 cannot be completely filled, as shown in FIG. 13, and a cavity 11 may be formed in the tungsten film 8. In this case, of course, when anisotropic dry etching is performed, the cavity 11 becomes large as shown in FIG. The cavities 11 are likely to occur when the tungsten film 8 has a high generation temperature and a high generation speed, or when the contact hole 7 has a negative slope. In order to prevent the formation of the cavity 11, as shown in FIG. 15, the contact hole 7A whose upper portion is enlarged by performing Wet etching + anisotropic dry etching using a hydrofluoric acid solution at the time of forming the contact hole is opened. Although it is sufficient to form the holes, when the tungsten film 8 is anisotropically dry-etched, the tungsten film 8 cannot be left precisely with a uniform thickness in the contact hole 7A as shown in FIG. Difficult,
In addition, since the residue 9 of the tungsten film 8 is naturally generated, there is a problem that the upper aluminum wiring is easily broken or short-circuited, and the yield is deteriorated.

The present invention has been made in order to solve the above problems and has a small amount of residue of a refractory metal film, and a semiconductor device in which a refractory metal film is almost completely buried in a contact hole, and a manufacturing method thereof. The purpose is to provide.

[0006]

A method of manufacturing a semiconductor device according to the present invention comprises a step of forming a contact hole in a first insulating film on one main surface of a semiconductor substrate, the step of forming a contact hole on the first insulating film, and the step of forming a contact hole on the first insulating film. A step of forming a refractory metal film in the contact hole; a step of ion-implanting impurities into the refractory metal film at least on the first insulating film; and a step of refractory melting at least on the first insulating film. And a step of removing the metal film by etching.

Further, a step of forming a contact hole in the first insulating film on the one main surface of the semiconductor substrate, a step of forming a refractory metal film on the first insulating film and in the contact hole, A step of forming a conductive film on the refractory metal film; a step of etching and removing the conductive film to expose at least the refractory metal film on the first insulating film; It includes a step of ion-implanting impurities into the film and a step of etching and removing at least the refractory metal film on the first insulating film.

Further, a step of forming a contact hole in the first insulating film on the one main surface of the semiconductor substrate, a step of forming a refractory metal film on the first insulating film and in the contact hole, Etching the second insulating film to remove at least the refractory metal film on the first insulating film; and implanting impurities into the refractory metal film. And a step of etching and removing the refractory metal film on the first insulating film.

Further, in the semiconductor device according to the present invention, the first insulating film formed on one main surface of the semiconductor substrate, the contact hole formed at a predetermined position of the first insulating film, and the contact The high melting point metal film deposited in the hole and the conductive film partially formed on the high melting point metal film are provided.

Further, a first insulating film formed on one main surface of the semiconductor substrate, a contact hole formed at a predetermined position of the first insulating film, and a high melting point deposited in the contact hole. A metal film and a second insulating film partially formed on the refractory metal film are provided.

[0011]

In the present invention, impurities are ion-implanted into the refractory metal film before the refractory metal film is removed by etching. As a result, the refractory metal film is brought into an amorophous state, and the residue of the refractory metal film when the refractory metal film is removed by etching can be reduced.

Before etching away the refractory metal film, a conductive film is formed on the refractory metal film, and the conductive film is etched and removed to remove at least the refractory metal film on the first insulation. After the exposure, impurities are ion-implanted into the refractory metal film. As a result, the refractory metal film becomes an amorphous state, the residue of the refractory metal film when etching and removing the refractory metal film can be reduced, and the refractory metal film can be formed without contact with the contact hole. It can be filled in accurately.

Before removing the refractory metal film by etching, a second insulating film is formed on the refractory metal film, and the second insulating film is etched and removed to remove at least the first insulating film. After the refractory metal film is exposed, impurities are ion-implanted into the refractory metal film. As a result, the refractory metal film becomes an amorphous state, the residue of the refractory metal film when etching and removing the refractory metal film can be reduced, and the refractory metal film can be formed without contact with the contact hole. It can be filled in accurately.

Further, the contact hole burying layer is a multilayer film of a conductive film and a refractory metal film. As a result, a contact hole having a refractory metal film embedded with high precision can be obtained.

Further, the buried layer of the contact hole is a multi-layer film of the second insulating film and the refractory metal film. As a result, a contact hole having a refractory metal film embedded with high precision can be obtained.

[0016]

Embodiments of the present invention will be described below with reference to FIGS. In each figure, portions corresponding to those in FIGS. 9 to 16 are designated by the same reference numerals and described. Example 1. 1 and 2 are sectional views showing an embodiment of the present invention in the order of manufacturing steps. In FIG. 1, first, as in the conventional case, a field oxide film 2, an N ⁺ impurity diffusion layer 3, a polycrystalline silicon film 4, a non-doped silicon oxide film 5, and a non-doped silicon oxide film 5 are formed on one main surface of a semiconductor substrate such as a P-type silicon substrate 1. B constituting the first insulating film together with the silicon oxide film 5
The PSG film 6 is sequentially formed, and the contact hole 7 is opened. Next, a refractory metal film, for example, a tungsten film 8 is deposited to a thickness of, for example, about 1 μm. After that, impurities 12 such as arsenic (As) 12 are added to, for example, 5E15 cm 2, 80.
It is implanted into the tungsten film 8 by using the ion implantation technique under the condition of KeV. At this time, the grains of the tungsten film 8 are crushed by the As ions 12 to be in an extremely small particle state (amorphophass state). Next, as shown in FIG. 2, the tungsten film 8 is anisotropically dry-etched using sulfur hexafluoride gas to form a buried layer of the tungsten film 8 in the contact hole 7. Next, aluminum wiring 10
And is connected to the tungsten film 8.

As described above, in this embodiment, since the tungsten film 8 in the amorphofus state in which the particles are extremely small is etched, the residue 9 of the tungsten film 8 is extremely unlikely to occur, and the patterning of the aluminum wiring 10 is improved.

Example 2. 3 to 5 are sectional views showing another embodiment of the present invention in the order of manufacturing steps. In FIG.
First, as in the conventional case, the field oxide film 2, the N ⁺ impurity diffusion layer 3, the polycrystalline silicon film 4, the non-doped silicon oxide film 5, and the BPSG film 6 are sequentially formed on one main surface of the P-type silicon substrate 1. Next, using a resist (not shown) as a mask, a part of the BPSG film 6 having a thickness of about 1/3 is etched with a hydrofluoric acid solution, and then the remaining oxide film is anisotropically dry-etched to form a contact. Open the hole 7A. Next, the tungsten film 8 is deposited to a thickness of, for example, about 1 μm.
Next, a conductive film having a slower etching rate than that, for example, a polycrystalline silicon film 13 doped with phosphorus is deposited on the tungsten film 8 by a low pressure CVD method using silane gas to have a thickness of, for example, about 0.6 μm. Next, as shown in FIG. 4, the polycrystalline silicon film 13 is anisotropically dry-etched using sulfur hexafluoride gas to expose the tungsten film 8.
At this time, a part of the polycrystalline silicon film 13 remains above the contact hole 7A. Then, As ions 12 are implanted into the tungsten film 8 by using the ion implantation technique as in the first embodiment. Next, as shown in FIG. 5, the tungsten film 8 is etched to fill the contact hole 7A with the tungsten film 8. At this time, the polycrystalline silicon film 13 may remain above the contact hole 7A. next,
Aluminum wiring 10 is formed and connected to the tungsten film 8.

At this time, naturally, the thickness of the vertical portion of the contact hole 7A, that is, the portion subjected to anisotropic dry etching is about 3/4 that of the conventional case (FIGS. 13 and 14), so that the tungsten as described above is used. The cavity of the film 8 is unlikely to occur. Further, the polycrystalline silicon film 13 is formed at about 600 ° C.
Done in. At this time, the grains of the tungsten film 8 grow and become larger than those at the time of deposition. Therefore, it is effective to break the grains by ion implantation. Further, if the tungsten film 8 is thickly deposited instead of depositing the polycrystalline silicon film 13, the contact hole 7A may be filled, but the grain of the tungsten film 8 becomes large and the thickness of the tungsten film 8 becomes large. If it is thick, it is difficult to crush all the grains. Polycrystalline silicon film 1
In the case of No. 3, the grains are less likely to grow than the tungsten film 8 and the embedding in the groove is easy. Therefore,
The tungsten film 8 is embedded in the contact hole 7A.
It is better to use a multilayer film of the tungsten film 8 and the polycrystalline silicon film 13 rather than only.

As described above, in this embodiment, the polycrystalline silicon film 13 is deposited on the tungsten film 8 before the tungsten film 8 is removed by etching, and the polycrystalline silicon film 13 is anisotropically dry-etched. And at least BP
Since the As ions 12 are implanted into the tungsten film 8 after the tungsten film 8 on the SG film 6 is exposed, the residue 9 of the tungsten film 8 can be reduced and
It is possible to suppress the generation of voids in the tungsten film 8 and bury the tungsten film 8 in the contact hole 7A with a uniform thickness with high precision.

Example 3. 6 to 8 are sectional views showing another embodiment of the present invention in the order of manufacturing steps. In FIG.
First, as in the conventional case, the field oxide film 2, the N ⁺ impurity diffusion layer 3, the polycrystalline silicon film 4, the non-doped silicon oxide film 5, and the BPSG film 6 are sequentially formed on one main surface of the P-type silicon substrate 1. Next, using a resist (not shown) as a mask, a portion of the BPSG film 6 having a thickness of about ½ is etched with a hydrofluoric acid solution, and then the remaining oxide film is anisotropically dry-etched to make contact. Open the hole 7A. Next, the tungsten film 8 is deposited to a thickness of, for example, about 1 μm.
Next, an insulating film having a slower etching rate, for example, a silicon oxide film 14 is formed on the tungsten film 8 by a low pressure CVD method using silane gas and oxygen gas, for example, about 0.5 μm.
m is deposited. Next, a liquid silicon oxide film 15 is applied on the silicon oxide film 14 to completely fill the holes above the contact holes 7A. Next, as shown in FIG. 7, the silicon oxide film 15 and the silicon oxide film 14 are anisotropically dry-etched. This anisotropic dry etching is performed relatively over, and the silicon oxide film 14 remaining on the contact holes 7A is thinned as much as possible. By this anisotropic dry etching, the etching rate ratio between the silicon oxide film 14 and the tungsten film 8 is about 50 times, and the tungsten film 8 remains sufficiently even in the case of overetching. Then, As ions 12 are implanted in the same manner as in the above embodiment,
As shown in FIG. 8, the tungsten film 8 is etched and left only in the contact hole 7A portion. At this time, part of the silicon oxide film 14 may remain above the contact hole 7A. Next, aluminum wiring 10 is formed and connected to the tungsten film 8.

As described above, in this embodiment, the silicon oxide films 14 and 15 are deposited on the tungsten film 8 before the tungsten film 8 is removed by etching, and the silicon oxide films 14 and 15 are anisotropically etched. Since at least the tungsten film 8 on the BPSG film 6 is exposed by dry etching and As ions 12 are implanted into the tungsten film 8, the residue 9 of the tungsten film 8 can be reduced and the cavity of the tungsten film 8 can be reduced. By suppressing the generation, the tungsten film 8 can be filled in the contact hole 7A with high accuracy so as to have a uniform thickness.

Example 4. In the third embodiment, the liquid silicon oxide film 1 is formed after the silicon oxide film 14 is deposited by the CVD method.
5 is generated, but it may be generated in the reverse order, or may be only the liquid silicon oxide film 15 if the portion of the contact hole 7A is filled. Therefore, the second insulating film may be composed of the silicon oxide film 14 and the liquid silicon oxide film 15 formed by the CVD method, or may be composed of only the liquid silicon oxide film 15.

In the method of forming the silicon oxide film 14 on the tungsten film 8 as described above, the silicon oxide film 14 is finally left as shown in FIG. Therefore, when the contact hole 7A is opened, it is necessary to make the diameter of the upper portion of the contact hole 7A relatively large. Even when the silicon oxide film 14 is used, it has the same filling effect as the polycrystalline silicon film 13.

Example 5. In each of the above-described embodiments, the case of performing As ion implantation as the impurity ion implantation has been described, but other impurity ion implantation may be used as long as it can crush the grains of the tungsten film 8. The etching of the tungsten film 8 may be isotropic dry etching, or a combination of isotropic dry etching and anisotropic dry etching. Also,
Although each of the above-described embodiments has been described with respect to the case where the tungsten film is used as the refractory metal film to fill the contact hole, it goes without saying that another refractory metal film such as a molybdenum film may be used. Further, a barrier metal such as titanium may be formed under the tungsten film.

[0026]

As described above, according to the present invention, the step of forming a contact hole in the first insulating film on the one main surface of the semiconductor substrate, and the step of forming the contact hole on the first insulating film and in the contact hole. A step of forming a refractory metal film, a step of implanting impurities into the refractory metal film on at least the first insulating film, and an etching of the refractory metal film on at least the first insulating film. And the step of removing the high melting point metal film is reduced, and a semiconductor device having a high yield can be obtained.

Further, a step of forming a contact hole in the first insulating film on the one main surface of the semiconductor substrate, a step of forming a refractory metal film on the first insulating film and in the contact hole, A step of forming a conductive film on the refractory metal film; a step of etching and removing the conductive film to expose at least the refractory metal film on the first insulating film; Since the step of ion-implanting impurities into the film and the step of removing at least the refractory metal film on the first insulating film by etching are included, the residue of the refractory metal film is reduced and a cavity is formed. Since the refractory metal film can be filled in the contact hole with high accuracy without being generated, wiring is facilitated, and a semiconductor device with a higher yield can be obtained.

Further, a step of forming a contact hole in the first insulating film on the one main surface of the semiconductor substrate, a step of forming a refractory metal film on the first insulating film and in the contact hole, Etching the second insulating film to remove at least the refractory metal film on the first insulating film; and implanting impurities into the refractory metal film. Since the step of etching and removing the refractory metal film on the first insulating film is included, the residue of the refractory metal film is reduced,
Further, since the refractory metal film can be filled in the contact hole with high precision without forming a cavity, wiring is facilitated, and a semiconductor device with a higher yield can be obtained.

Further, a first insulating film formed on one main surface of the semiconductor substrate, a contact hole formed at a predetermined position of the first insulating film, and a high melting point deposited in the contact hole. Since the metal film and the conductive film partially formed on the refractory metal film are provided, there is an effect that a semiconductor device with a high yield can be obtained.

Further, a first insulating film formed on one main surface of the semiconductor substrate, a contact hole formed at a predetermined position of the first insulating film, and a high melting point deposited in the contact hole. Since the metal film and the second insulating film partially formed on the refractory metal film are provided, there is an effect that a semiconductor device with a high yield can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention in the order of manufacturing steps.

FIG. 2 is a sectional view showing an embodiment of the present invention in the order of manufacturing steps.

FIG. 3 is a sectional view showing another embodiment of the present invention in the order of manufacturing steps.

FIG. 4 is a cross-sectional view showing another embodiment of the present invention in the order of manufacturing steps.

FIG. 5 is a cross-sectional view showing another embodiment of the present invention in the order of manufacturing steps.

FIG. 6 is a sectional view showing still another embodiment of the present invention in the order of manufacturing steps.

FIG. 7 is a sectional view showing still another embodiment of the present invention in the order of manufacturing steps.

FIG. 8 is a sectional view showing still another embodiment of the present invention in the order of manufacturing steps.

FIG. 9 is a cross-sectional view showing an example of a conventional method of manufacturing a semiconductor device in the order of manufacturing steps.

FIG. 10 is a cross-sectional view showing an example of a conventional method of manufacturing a semiconductor device in the order of manufacturing steps.

FIG. 11 is a cross-sectional view showing an example of a conventional semiconductor device manufacturing method in the order of manufacturing steps.

FIG. 12 is a cross-sectional view showing an example of a conventional semiconductor device manufacturing method in the order of manufacturing steps.

FIG. 13 is a cross-sectional view showing another example of the conventional method of manufacturing a semiconductor device in the order of manufacturing steps.

FIG. 14 is a cross-sectional view showing another example of the conventional method for manufacturing a semiconductor device in the order of manufacturing steps.

FIG. 15 is a cross-sectional view showing another example of the conventional method of manufacturing a semiconductor device in the order of manufacturing steps.

FIG. 16 is a cross-sectional view showing another example of the conventional method of manufacturing a semiconductor device in the order of manufacturing steps.

[Explanation of symbols]

 3 p-type silicon substrate 5 non-doped silicon oxide film 6 BPSG film 7,7A contact hole 8 tungsten film 12 As ions 13 polycrystalline silicon film 14, 15 silicon oxide film

Claims (7)

[Claims] 1. A step of forming a contact hole in a first insulating film on a main surface of a semiconductor substrate; a step of forming a refractory metal film on the first insulating film and in the contact hole; A step of ion-implanting impurities into the refractory metal film on the first insulating film; and a step of etching and removing at least the refractory metal film on the first insulating film. And a method for manufacturing a semiconductor device. 2. A step of forming a contact hole in a first insulating film on a main surface of a semiconductor substrate, a step of forming a refractory metal film on the first insulating film and in the contact hole, Forming a conductive film on the refractory metal film; etching the conductive film to expose at least the refractory metal film on the first insulating film; and A method of manufacturing a semiconductor device, comprising: a step of ion-implanting impurities into the film; and a step of etching and removing at least the refractory metal film on the first insulating film. 3. A step of providing a contact hole in a first insulating film on a main surface of a semiconductor substrate, a step of forming a refractory metal film on the first insulating film and in the contact hole, At least exposing the refractory metal film on the first insulating film by etching and removing the second insulation film; and implanting impurities into the refractory metal film. And a step of etching and removing the refractory metal film on the first insulating film. 4. The method for manufacturing a semiconductor device according to claim 2, wherein at least a part of the contact hole has a taper, and the width of the uppermost surface is larger than the width of the lowermost surface. 5. A first substrate formed on one main surface of a semiconductor substrate.
Insulating film, a contact hole formed at a predetermined position of the first insulating film, a refractory metal film deposited in the contact hole, and a partly formed on the refractory metal film. A semiconductor device comprising a conductive film. 6. A first substrate formed on one main surface of a semiconductor substrate.
Insulating film, a contact hole formed at a predetermined position of the first insulating film, a refractory metal film deposited in the contact hole, and a partly formed on the refractory metal film. A semiconductor device comprising a second insulating film. 7. The semiconductor device according to claim 5, wherein at least a part of the contact hole has a taper, and the width of the uppermost surface is larger than the width of the lowermost surface.