JP2000294775A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a method of manufacturing a semiconductor device wherein abnormal oxidation of metal silicide films formed on a semiconductor substrate can be suppressed. SOLUTION: After metal silicide films 4 and 5 are formed on a semiconductor substrate 1, the resulting member is annealed in an atmosphere of SiXHYClZ (where X, Y and Z indicate the composition percentages of the respective elements), to thereby improve the crystallinity of the films 4 and 5 and supply Si in the SiXHYClZ gas to the films 4 and 5. As a result, the films 4 and 5 can contain larger amounts of Si after growth. This prevents abnormal oxidation from occurring on the films 4 and 5 even when the films 4 and 5 are exposed to a high-temperature oxygen atmosphere during subsequent heat treatments.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor device having a metal silicide film on a semiconductor substrate, and more particularly to a method for manufacturing a semiconductor device for suppressing abnormal oxidation of a metal silicide film.

[0002]

2. Description of the Related Art FIG. 4 is a schematic sectional view for explaining a conventional method for manufacturing a semiconductor device using a metal silicide film.
The semiconductor device is, for example, a MOS transistor,
The step of forming the gate electrode will be described.

Referring to FIG. 4A, first, the surface of Si substrate 1
A gate oxide film (SiO_Two Film) 2 having a thickness of about 5 nm
A film is formed. Then, on the gate oxide film 2, for example,
Doped (added) polysilicon film with low resistance
3 was formed to a thickness of about 100 nm by the CVD method under the following conditions.
You. The conditions are a substrate temperature of 620 ° C. and a processing chamber pressure of 1
0.6 kPa, the gas supplied on the gate oxide film 2 and the
Each flow rate is SiH _Four / H_Two / PH_Three = 0.45s
lm / 10 slm / 20 sccm.

Since the polysilicon film 3 is a semiconductor, there is a limit in reducing the resistance even if phosphorus is doped. Accordingly, by laminating a metal silicide film of tungsten silicide (WSi _X), etc. which is a compound of a refractory metal and silicon such as tungsten, on the polysilicon film 3, that is, constituting the gate electrode of the polycide structure, further Low resistance.

The WSi _x film includes a first WSi _x film 4 formed on the polysilicon film 3 and a second WSi _x film 4 formed on the first WSi _x film 4.
WSi _x film 5. For example, the first WSi _x film 4 has a substrate temperature of 595 ° C., a pressure of 133 Pa, a supplied gas and its flow rate, and SiH ₂ Cl ₂ / WF ₆ = 300 sc.
A film is formed at a film thickness of about 10 nm by a CVD method at cm / 3 sccm. The composition ratio of W and Si in the first WSi _X film 4 has a Si / W = 3.0. Second W
The Si _x film 5 is formed, for example, at a substrate temperature of 595 ° C. and a pressure of 133.
Pa, supplied gas and its flow rate, SiH ₂ Cl ₂ / W
A film is formed at a thickness of about 90 nm by a CVD method at F ₆ = 100 sccm / 3.6 sccm. The composition ratio of W and Si in the second WSi _X film 5 has a Si / W = 2.6.

[0006] In the case of WSi _X film to be formed in the SiH ₂ Cl ₂ reduction, unlike the WSi _X film formed by SiH ₄ reduction,
The composition ratio in the film thickness direction has a gradient, the amount of Si is small at the interface with the polysilicon film 3, and the amount of Si increases toward the surface. If a layer containing a large amount of W (W-rich layer) is formed at the interface with the underlying polysilicon film 3, abnormal oxidation (formation of tungsten oxide) occurs in the subsequent heat treatment step. This is due to the heat treatment of WSi _x
The diffusion of Si in the film into the polysilicon film 3 reduces the Si content at the interface. However, if the interface is already a W-rich layer in the state after film formation, W is oxidized to cause a volume change, A good-shaped polycide gate cannot be obtained. And interface the first WSi _X film 4 Si / W composition ratio than normal is large, i.e. to form a Si-rich layer between the polysilicon film 3 in order to prevent this.

In addition, the first and second WSi_X film
For the formation by CVD method 4 and 5, S is used as a source gas.
iH_Two Cl_Two And WF₆ Which is SiH_Four 
And WF ₆ W formed as compared with the case where it is formed using
Si_X To reduce the content of F contained in the films 4 and 5
Can be. WSi_X High content of F in films 4 and 5
F diffuses into the gate oxide film 2 by the subsequent heat treatment
Then, the bond between Si and O in the gate oxide film 2 is cut off,
-F bond is taken. Thereby, the gate oxide film 2
Film quality, gate capacitance, breakdown voltage, etc.
Wake up.

Next, as shown in FIG. 4B, the second W
An SiO ₂ film 6 is formed on the Si _X film 5. This film is formed, for example, by a CVD method at a substrate temperature of 700 ° C. and a pressure of 5 ° C.
0 Pa, the supplied gas and its flow rate were TEOS [Si
(OCH ₂ CH ₃ ) ₄ ] at 130 sccm and a film thickness of about 2
A film is formed at a thickness of 50 nm. Step during photolithography for forming a gate electrode in a later Without this SiO ₂ film 6, or the line width becomes thick due to the influence of the surface roughness of the second WSi _X film 5, resulting in or thinner Therefore, by forming an SiO ₂ film having excellent step coverage (particularly, a film formed by TEOS), the exposure accuracy at the time of photolithography can be improved. Also, it is used as an inorganic mask at the time of gate processing, and the workability is also improved. Also, S
When depositing the iO ₂ film 6, the composition of the underlying WSi _X film already diffused Si WSi _X film 4,5 are substantially equal to be a single film. Furthermore, Si is a polysilicon film 3 is the interface of WSi _X film, LP-TEOS (SiO ₂
Film 6) deposited at the interface, Si composition ratio of WSi _X film itself is decreased.

Thereafter, although not shown, the SiO ₂ film 6
A photoresist is applied on the substrate, and exposure and development are performed to form a resist pattern 7 as shown in FIG. 4C.

[0010] Then, the resist pattern 7 as a mask, SiO ₂ film 6, first and second WSi _X film 4,
5, the polysilicon film 3 and the gate oxide film 2 are etched and the resist pattern 7 is stripped to form the gate electrode 11 shown in FIG. 4D.

[0011]

After this, the gate electrode 1
1 is exposed to a high-temperature (for example, 700 ° C. or higher) oxidizing atmosphere at the time of forming a SiO ₂ film such as a protective film or an interlayer insulating film at the time of ion implantation for forming source / drain diffusion layers. Causes abnormal oxidation of the _X film. this is,
The formation of the SiO ₂ film 6 shown in FIG.
This is a heat treatment at 00 ° C., in which the first and second WS
Si in i _X films 4 and 5 is Si / W in the WSi diffuse decreases.

The WSi _x film 5 having a low Si content has
When the heat treatment in a high-temperature oxidizing atmosphere as described above is applied,
More W is oxidized. The oxide of W has a larger volume than that of simple W, and thus the volume change accompanying the formation of tungsten oxide causes the oxide 8a in FIG.
In As shown, the shape of WSi _X film deteriorates. The first and second WSi _X film 4 and 5 Si / W in the heat treatment at this time is a single layer of substantially uniform WSi _X film 8. Also, in FIG. 4E, illustration of, for example, a protective film for ion implantation formed by heat treatment in a high-temperature oxidizing atmosphere is omitted.

The deterioration of the shape of the WSi _x film 8, that is, the deformation of the shape of the gate electrode 11, cannot satisfy the demand for precise dimensional accuracy accompanying the recent high integration. Further, WSi _X film contains much tungsten oxide resistance increases. Thus, the occurrence of abnormal oxidation causes a decrease in transistor characteristics and a decrease in yield.

Further, as another conventional example, after the formation of the gate electrode 11 shown in FIG. 4D, for example, a substrate temperature of 800 ° C., N ₂
30 minutes in a gas atmosphere, there is a method of performing an annealing treatment in order to improve the crystallinity of WSi _X film, thereby prevent the abnormal oxidation. However, this is after the formation of WSi _X film 5 shown in FIG. 4A, it is not performed any example 600 ° C. or more heat-treated has been assumed. That is, the gate electrode 1
After the formation of No. 1, Si is converted to WSi _x by annealing.
Since the Si is diffused also to the side surface of the film 5 and thus, even if exposed to a high-temperature oxidizing atmosphere, the Si diffused to the side surface is oxidized, so that the oxidation of W can be suppressed and abnormal oxidation does not occur. However, if the heat treatment for forming the SiO ₂ film 6 as shown in FIG. 4B is performed before the formation of the gate electrode 11, Si is already diffused in the film thickness direction by the heat treatment at this time, and WSi _x Si / W in the film 5 decreases. Therefore, even if annealing is performed after the formation of the gate electrode 11, abnormal oxidation cannot be suppressed.

Further, JP-A-8-191102, by forming an amorphous silicon film on the bottom or WSi _X film, S an amorphous silicon film during thermal treatment
i is shown to be supplied to the WSi _X film prevents abnormal oxidation of WSi _X film. Further, JP-A-8-78411, in Si-N ₂ bond layers of the film to form a SiO ₂ film containing nitrogen on the WSi _X film, the oxidizing species reaching the WSi _X film Try to prevent. But,
These include amorphous silicon films and nitrogen-containing S
An iO ₂ film must be formed, which increases the number of steps and increases manufacturing costs.

The present invention has been made in view of the above problems, and provides a method of manufacturing a semiconductor device capable of suppressing abnormal oxidation of a metal silicide film formed on a semiconductor substrate without forming any new film. That is the task.

[0017]

[Means for Solving the Problems] To solve the above problems
According to the present invention, a metal silicide film is formed on a semiconductor substrate.
After forming_X H_Y Cl_Z (X, Y, and Z are each element
By performing the annealing treatment in the atmosphere,
Improve the crystallinity of the metal silicide film and _X H_Y C
l_Z The Si in the gas is supplied to the metal silicide film
To increase the Si content of the metal silicide film after film formation
be able to. As a result, high-temperature acid
Abnormal oxidation of metal silicide film even when exposed to
Does not occur.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

1 to 3 are schematic cross-sectional views for explaining a method of manufacturing a semiconductor device using a metal silicide film according to the present embodiment. As in the conventional example, the semiconductor device is, for example, a MOS transistor. The step of forming the gate electrode will be described.

FIG. 1A shows the conventional example of FIG. 4A described above.
It has exactly the same configuration as. That is, the Si substrate 1
A gate oxide film (SiO ₂ film) 2 on the surface of
nm. A polysilicon film 3 doped with, for example, phosphorus is formed on the gate oxide film 2 by a CVD method under the following conditions to a thickness of about 100 nm. The conditions are a substrate temperature of 620 ° C. and a processing chamber pressure of 10.6 k.
Pa, the gas supplied on the gate oxide film 2 and the respective flow rates are SiH ₄ / H ₂ / PH ₃ = 0.45 slm / 1.
0 slm / 20 sccm.

Next, by forming a WSi _X film 4,5 purposes low resistance on the polysilicon film 3, i.e., constitute a gate electrode of the polycide structure. First WSi _X film 4 formed on the polysilicon film 3, for example,
Substrate temperature 595 ° C., pressure 133 Pa, supplied gas and its flow rate, SiH ₂ Cl ₂ / WF ₆ = 300 sccm /
A film is formed to a thickness of about 10 nm by a CVD method at 3 sccm. The composition ratio of W and Si in the first WSi _X film 4 has a Si / W = 3.0. First WSi
The second WSi _X film 5 formed on the _X film 4 has, for example, a substrate temperature of 595 ° C., a pressure of 133 Pa, a supplied gas and its flow rate, and SiH ₂ Cl ₂ / WF ₆ = 100 scc.
The thickness is about 90 nm by the CVD method at m / 3.6 sccm.
Is formed. W and Si in the second WSi _X film 5
Is Si / W = 2.6.

As described in detail in the description of the prior art, ordinary Si
The first WSi _x film 4 rich in Si is formed under the second WSi _x film 5 having the / W composition ratio because a layer containing a large amount of W at the interface with the polysilicon film 3 (W This is to prevent the occurrence of abnormal oxidation (formation of tungsten oxide) in the subsequent heat treatment step due to the formation of the (rich layer).

The first and second WSis
_In forming the _X films 4 and 5 by the CVD method, SiH ₂ Cl ₂ and WF ₆ are used as source gases, but this also reduces the content of F contained in the formed WSi _X films 4 and 5. Then, the diffusion of F prevents the quality of the gate oxide film 2 and the breakdown voltage from being lowered.

Next, in the present embodiment, the WSi _x film 4,
Annealing is performed in a SiH ₂ Cl ₂ atmosphere in the same processing chamber where 5 is formed. The substrate temperature is 625 ° C., the processing chamber pressure is 133 Pa, and the supply amount of the SiH ₂ Cl ₂ gas is 100.
This is performed under the condition of sccm. This is the same gas atmosphere and the same pressure as the SiH ₂ Cl ₂ used for forming the WSi _x films 4 and 5. That is, since only the substrate temperature is changed, the annealing treatment can be performed in the same processing chamber as it is. it can. By this annealing treatment, S in the WSi _x films 4 and 5
i causes diffusion, but Si in SiH ₂ Cl ₂ becomes WSi
Since it is supplied into the _X film 5, the composition ratio of Si / W does not decrease. In addition, the WS treatment allows the WS
The non-crystalline state or hexagonal state immediately after formation of the i _X films 4 and 5, more crystals change in the non stable, and be more improved to tetragonal low resistance. That is, as shown in FIG. 1B, the annealing treatment in the SiH ₂ Cl ₂ atmosphere
Second WSi _X film 5 will WSi _X film 5 'of more and tetragonal structure with Si content.

Next, as shown in FIG. 2A, a photo for forming a gate electrode in a later step is formed on the second WSi _x film 5 ′ which has been subjected to the above-described annealing treatment, similarly to the conventional case. SiO to improve exposure accuracy during lithography
_Two films 6 are formed. This film is formed by, for example, a CVD method at a substrate temperature of 700 ° C., a pressure of 50 Pa, a supplied gas and a flow rate of TEOS [Si (OCH ₂ CH ₃ ) ₄ ] of 130 sccm, and a film thickness of about 250 nm.

Thereafter, although not shown, the SiO ₂ film 6
A photoresist is coated on the substrate, and a resist pattern 7 is formed by exposure and development as shown in FIG. 2B.

[0027] Then, the resist pattern 7 as a mask, SiO ₂ film 6, WSi _X film 4,5 ', the polysilicon film 3, a gate oxide film 2 is etched, and the resist pattern is removed 7, Figure 3A Gate electrode 10 shown
Is formed. For example, the etching of the WSi _x films 4, 5 ′ is performed by plasma etching, and the pressure in the processing chamber is 1.8.
mTorr, high-frequency power RF = 600 W, and etching gas Cl ₂ are supplied at 25 sccm. The polysilicon film 3 is formed, for example, by etching gas Cl ₂ = 30 scc.
m, HBr = 30 sccm, pressure 2.0 mTorr, high frequency power RF = 600 W plasma etching.

The gate electrode 10 according to the present embodiment formed as described above is thereafter
But, for example, a high temperature when forming the SiO ₂ film such as a protective film or an interlayer insulating film in ion implantation for forming the source-drain diffusion layer (for example 700 ° C. or higher) WSi _X film even when exposed to an oxygen atmosphere No abnormal oxidation occurs. This is shown in FIG.
Shown in The first and second WSi _x films 4 and 5 ′ are monolayered into a WSi _x film 9 having substantially uniform Si / W by the heat treatment at this time. The illustration of a protective film for ion implantation and the like is omitted.

That is, as shown in FIG. 1B, SiH ₂ Cl ₂
By the annealing treatment in the atmosphere, the WSi _x film 9 becomes Si
Since Si is firmly incorporated into the film having a large content and the stable tetragonal structure, the oxidation of Si suppresses the oxidation of W to prevent abnormal oxidation.
Thus, the deformation of the shape of the gate electrode 10 can be prevented, the resistance does not increase, and a decrease in transistor characteristics and a decrease in yield can be prevented.

Although the embodiment of the present invention has been described above, the present invention is, of course, not limited to this, and various modifications can be made based on the technical idea of the present invention.

In the above embodiment, the annealing is performed in the SiH ₂ Cl ₂ atmosphere. However, the present invention is not limited to this, and other compounds represented by the chemical formula of Si _X H _Y Cl _Z may be used.
For example, SiH ₄ , SiH ₂ Cl ₂ , Si ₂ H ₆ , Si
₃ H ₈ , SiCl ₄ , SiHCl ₃ , SiH ₃ Cl or the like may be used. The gas used with WF ₆ in forming the WSi _X film is also not limited to SiH ₂ Cl _2, in correspondence with the gas when performing these annealing, using the same gas, WSi _X film in the same processing chamber Can be formed and an annealing treatment can be performed.

Further, in the above embodiment has been formed by dividing the WSi _X film in two layers, not limited to this, WS
i may be deposited in a single layer by _X film formed at the temperature of the source gas type of the substrate used in.

Further, in the above embodiment, although the gate of polycide structure composed of a WSi _X film and the polysilicon film is not limited to this, to form a direct WSi _X film on the gate oxide film A silicide gate may be used.

Further, in the above embodiment, WSi _X film as the metal silicide film is used in the gate electrode material is not limited to this, for example, as used in the material of the wiring that fills the contact hole You may.

Further, in the above embodiments, although the only WSi _X film as the metal silicide film is not limited to this, other metal silicide, for example in particular be such as TiSi _2, MoSi ₂ refractory metal . However, TiS
i _2, MoSi ₂ is difficult to film formation by application of CVD technology, good step coverage, such as when forming the WSi _X film by the CVD method, it is not obtained control of the film quality.

Further, in the above embodiment, although the formation of the SiO ₂ film 6 as a heat treatment step before the gate electrode formation is not limited to this, formation of the film other than SiO ₂ film,
Alternatively, the gate oxide film 2, the polysilicon film 3, the WSi
_Some heat treatment for improving the film quality of the _X films 4 and 5 may be performed.

[0037]

As described above, according to the method of manufacturing a semiconductor device according to the first aspect of the present invention, a metal silicide film having a high Si content can be formed, and abnormal oxidation of the metal silicide film is suppressed. it can.

Further, according to the method of manufacturing a semiconductor device according to the second aspect of the present invention, a quick annealing process can be performed without taking much time and effort.

According to the method of manufacturing a semiconductor device according to the third aspect of the present invention, when photolithography is performed on a metal silicide film, the exposure accuracy can be improved.

Further, according to the method of manufacturing a semiconductor device according to the fourth aspect of the present invention, a low-resistance gate electrode can be manufactured.

Further, according to the method of manufacturing a semiconductor device according to the fifth aspect of the present invention, it is possible to form a metal silicide film excellent in step coverage and controllability of film quality.

According to the method of manufacturing a semiconductor device according to the sixth aspect of the present invention, abnormal oxidation occurring at the boundary between the metal silicide film and the underlayer can be prevented.

[Brief description of the drawings]

FIG. 1 shows a method for manufacturing a semiconductor device according to an embodiment of the present invention.
FIG. 1 is a schematic cross-sectional view (part 1) for explaining a method, in which A denotes WSi
_X The state after film formation is shown, where B is the WSi of A_X SiH film
_Two Cl_Two 4 shows a step of performing an annealing process in an atmosphere.

Schematic cross-sectional views illustrating a method of manufacturing a semiconductor device according to the embodiment of the present invention; FIG an (Part 2), A is SiO ₂ film is formed on the WSi _X film annealing process has been performed B indicates a state where a resist pattern is formed on the SiO ₂ film.

FIG. 3 is a schematic cross-sectional view (part 3) illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention, wherein A shows a state where a gate electrode is formed by etching, and B shows A
Shows the gate electrode after heat treatment is performed on the gate electrode in the oxygen atmosphere.

Figure 4 is a schematic cross-sectional views illustrating a method of manufacturing a conventional semiconductor device, A is shows a state after the WSi _X film, B
Shows a state where the SiO ₂ film is formed on the WSi _X film, C is shows a state in which the resist pattern is formed on the SiO ₂ film, D is shows a state in which the gate electrode is formed by etching, E denotes a gate electrode obtained by subjecting the gate electrode in the state of D to heat treatment in an oxygen atmosphere.
Indicates that the _X film was abnormally oxidized.

[Explanation of symbols]

 1 ... Si substrate, 2 ... Gate oxide film, 3 ... Polysilicon
Con film, 4 ... WSi _X Film, 5 ... WSi_X Membrane, 5 '...
... WSi_X film.

Continued on front page F-term (reference) 4M104 AA01 BB01 BB37 BB38 BB40 CC05 DD43 DD65 DD78 FF14 GG09 HH18 5F004 AA16 BA04 BB13 DA00 DA04 DB02 DB03 DB15 DB17 EB02 5F033 HH04 HH27 HH28 HH29 LL06 Q09Q09 Q09 PP08 QQ73 QQ84 QQ85 QQ98 RR04 SS04 SS13 VV06 WW10 XX20 5F040 DA00 DA06 DA19 DC01 EC01 EC02 EC04 EC07 EC09 EC13 EJ03 FC00

Claims (6)

[Claims] To 1. A semiconductor substrate after the step of forming a metal silicide film, method of manufacturing a semiconductor device having a heat treatment step, after formation of the metal silicide layer, Si _X H _Y Cl _Z
(X, Y, Z: composition ratio of each element) A method of manufacturing a semiconductor device, wherein an annealing process is performed in an atmosphere, and then the heat treatment process is performed. 2. The method according to claim 1, wherein said metal silicide film is formed using Si _x H.
_{2. The} annealing process according to claim 1, wherein the annealing process is performed in the Si _X H _Y Cl _Z atmosphere in a processing chamber in which the metal silicide film is formed using _Y Cl _Z.
13. The method for manufacturing a semiconductor device according to item 5. 3. The method according to claim 1, wherein the heat-treating step comprises forming a SiO ₂ film on the metal silicide film. 4. A gate electrode having a polycide structure, wherein a gate oxide film and a polysilicon film are sequentially formed between the semiconductor substrate and the metal silicide film from the semiconductor substrate side. 3. The method for manufacturing a semiconductor device according to claim 1, wherein: 5. The method according to claim 1, wherein the metal silicide film is a tungsten silicide film. 6. The tungsten silicide film includes a first tungsten silicide film and a second tungsten silicide film formed sequentially from the semiconductor substrate side, and a ratio of silicon to tungsten in the first tungsten silicide film. 6. The method according to claim 5, wherein Si / W is larger than the second tungsten silicide film.