JPS63272049A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To facilitate building up a metal film on a metal nitride layer by a CVD method with excellent reproducibility and in a short time and, moreover, facilitate avoiding the reaction between the metal and silicon securely by employing the mixed gas of metal halide gas and hydrogen gas containing silicon hydride gas. CONSTITUTION:When a semiconductor device is manufactured by a step of forming a metal film 14 on a semiconductor substrate 11 with a metal nitride layer 13 between, the metal film 14 is built up on the metal nitride layer 13 by a chemical vapor growth method employing the mixed gas of metal halide gas and hydrogen gas containing silicon hydride gas. For instance, after an SiO2 film 12 with a thickness of 0.8mum is formed on the Si substrate 11, the TiN film 13 with a thickness of 500Angstrom is formed by a sputtering method. Then, the W film 14 with a thickness of 0.2mum is formed on the TiN film 13 with a substrate temperature of 380 deg.C by an LP-CVD method employing the mixed gas of H2, SiH4 and WF6. After that, a wiring pattern is formed by lithography and reactive ion etching.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device that improves wiring layer connections.

(Prior art) In recent years, as a method for forming electrode wiring for openings provided in an insulating film formed on a Si substrate, hydrogen (H2) and 6F have been used instead of sputtering using a material mainly composed of A. Chemical vapor deposition (CVD) using tungsten oxide (WF6) gas
A method of forming a W film using a method (method) has been proposed. In this method, since the reaction rate on the substrate surface is the dominant factor that determines the deposition rate, a significant improvement in step coverage is achieved compared to conventional sputtering methods.

However, the adhesion between the W film and the base oxide film (S i 02 film) is weak, and the stress between the W film and the Sl substrate cannot be withstood, resulting in frequent peeling of the W film. Therefore, the surface shape of the W film loses its flatness, making subsequent pattern processing difficult. Also, if the W film is made thinner to prevent peeling, the center of the opening will become a recess, so an insulating film is deposited on the upper layer and a second opening is formed directly above the opening. In this case, the thickness of the insulating film differs locally. For this reason, uniform etching is difficult, and there is a risk of poor contact at the connection portion.

As a method to solve this problem, a method has recently been proposed in which a metal layer with good adhesion is provided between the W film and the Sl substrate. In particular, it has good adhesion with the lower layer and has an electrical resistivity of 100μΩ1 or less, and the W deposited on the upper layer
The reaction between the film and the underlying Sl substrate is carried out at high temperature (700°C).
Examples of substances that can inhibit the above) include Ti, Zr, Hf,
Nb.

Nitrides such as Ta, Mo, and W are effective.

However, it has been found that when a conventional WF6 hydrogen reduction method is used to deposit a W film on these metal nitride layers by CVD, the growth rate of the W film is extremely slow or the W film is not deposited. That is, CVD using hydrogen reduction method of WF6
In law, A-no.

Although a W film with a desired thickness can be formed on W and Si with good controllability, extremely unstable W film growth was observed on metal nitride, which is the same conductive material. Although a metal film can be formed on a metal nitride layer without any problem using the sputtering method, in this case, as mentioned above, there is a problem in terms of step coverage. Therefore, there is a need for a technique for forming a metal film on a metal nitride layer using a CVD method with good reproducibility.

On the other hand, high-melting point metal nitrides have a larger free energy drop caused by compound formation than intermetallic compounds and have conductivity, so they are effective as reaction barriers, and TiN, ZrN, HfN, etc. have been applied so far. There is. Usually, since the contact resistance between these metal nitrides and Si is high, a metal silicide is formed by interposing a silicide or a metal layer between them in advance and performing heat treatment. However, using W, which is one of the high melting point metals, W/T i
When realizing the N/T L S i2/S i structure, 90
Heat treatment at temperatures exceeding 0° C. causes significant outward diffusion of Sl atoms, resulting in an extremely high rate of silicidation of W. In addition, even in the A, 4F/TiN/TiSi2/Si structure, if heat treatment such as slightly oxidizing the TiN surface layer is not performed, A will break through the TiN and invade the Sl substrate at about 450'C. , bond breakdown etc. are likely to occur in the S1 layer.

(Problems to be Solved by the Invention) As described above, in the conventional method of forming a metal film of a desired thickness on a semiconductor, an insulating film formed thereon, or a metal nitride layer formed on a metal film, using the CVD method, However, it is difficult to form a metal film of a desired thickness with good reproducibility in a short time. Further, even if a metal nitride layer is used as a reaction barrier, it is difficult to reliably prevent the reaction between metal and Si.

The present invention has been made in consideration of the above circumstances, and its purpose is to be able to deposit a metal film on a metal nitride layer using the CVD method with good reproducibility and in a short time, and to improve throughput. An object of the present invention is to provide a method for manufacturing a semiconductor device that can be measured.

Another object of the present invention is to provide a method for manufacturing a semiconductor device that can reliably prevent the reaction between metal and SL and can realize a highly reliable metal/St contact.

[Structure of the Invention] (Means for Solving the Problems) The gist of the present invention is to facilitate the growth of a metal film on a metal nitride layer by selecting the gas used in the CVD method. . Furthermore, the purpose is to increase the reaction barrier effect by adding too much nitrogen in the metal nitride layer.

That is, the present invention provides a method for manufacturing a semiconductor device including a step of forming a metal film on a semiconductor substrate via a metal nitride layer, in which a mixed gas of a metal halide gas and a hydrogen gas containing a silicon-hydrogen compound gas is used. In this method, the metal film is deposited on the metal nitride layer by a chemical vapor deposition method using.

The present invention also provides a method for manufacturing a semiconductor device including a step of forming a metal film on a semiconductor substrate via a metal nitride layer, in which the metal nitride layer has an initial average composition of metal-nitrogen of the metal nitride. This is a method of forming the metal nitride in such a way that the nitrogen content is in excess of that of the metal nitride that is formed between the metal nitrides and has the highest nitrogen content.

(Function) According to the present invention, by forming a metal film on a semiconductor substrate by the CVD method via a metal nitride layer, it is possible to form a metal film on the semiconductor substrate with good adhesion and good step coverage and electrical conductivity. It becomes possible to form a wiring layer. Furthermore, in the CVD method for forming metal films, the inclusion of silicon-hydrogen compound gas in hydrogen creates many nucleation sites on the metal nitride, which allows the desired film thickness to be achieved. It becomes possible to form a metal film in a short time with good reproducibility.

In addition, by adding too much nitrogen to the metal nitride layer, nitrogen can be precipitated at the nitride grain boundaries, preventing unreacted metal from remaining in the nitride layer, and reducing the amount of nitrogen at the interface with the metal and inside the nitride. It is possible to suppress the diffusion of metal or St at grain boundaries and maintain the thermal stability of the metal/St structure up to higher temperatures. Therefore, good contact characteristics and good P
It becomes possible to obtain N-junction characteristics. Therefore, low-resistance wiring can be formed with high reliability, and it is also possible to increase the density and integration of semiconductor devices.

(Example) Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a sectional view showing the manufacturing process of a semiconductor device according to the first embodiment method of the present invention. First, as shown in FIG. 1(a), a p-type (100) St substrate 11 with a specific resistance of 6Ωα
SiH4 and N2 were added to the top at 400℃ using the LP-CVD method.
0.8 μm Si02 film 12 using a mixed gas with 0.
followed by 500 TiNHC metal nitride layers)
form 13. The TiN film 13 was formed by sputtering at a substrate temperature of 200''C17) using a Ti target in a mixed gas of N2 and Ar (50% each) at a pressure of 5 mTorr.

Next step: LP-CVD method Niyori hydrogen (N2).

Monosilane (SiH4) and tungsten hexafluoride (WF
Using the mixed gas of 6), N2 was set at 0.173 Torr.

SiH4 at O,013 Torr, W F6 at O,0
At a substrate temperature of 380° C. and maintaining a partial pressure of B5 Torr, an upper film (metal film) 14 of 0.2 μm is formed on the TIN film 1 and 3 as shown in FIG. 1(b). The time was 2 minutes and 40 seconds.Then, as shown in Figure 1(C), regular lamination and reactive ion etching (RI) were performed.
Process the wiring pattern using E).

Note that when carrying out the above CVD method, a cold wall type CVD apparatus as shown in FIG.
The substrate was heated by the heater 24, and a predetermined gas was introduced into the reaction furnace 21 to grow a W film, a 5to2 film, and the like.

Here, the amount of SiH4 added when growing the W film was O.013 Torr, and the amount of St contained in the W film at this time was 1.3 to 1.8 according to SIMS analysis.
It was about %. Furthermore, when the growth rate of the W film is plotted against the amount of SiH4 added, the result is as shown in FIG. S
Without iH4 addition, it is 0 to 48 people/win, and 0
．． 750 people/win at SiH4 partial pressure of 013Torr
s O, 1400 people/gin at 026 Torr
As a result, the stability of growth rate has improved dramatically. Also,
If the base is W, 200 people / even without the addition of SiH4.
The growth rate was stable at gin.

Thus, according to the method of this embodiment, CV
By adding 5tH4 to the mixed gas of WF6 and H2 as the gas used in the D method, that is, by adding SiH to H2 as a carrier gas, the reproducibility on the TiN film 1 layer can be increased by 3 times faster. The W film 14 can be grown well.

Here, the TiN film 13 has good adhesion to the underlying 5to2 film 12, and furthermore, the adhesion between the TiN film 13 and the W film 14 is extremely good. Therefore, the W film 14 can be formed with good adhesion on the Si 02 film 12, which is extremely effective in forming wiring patterns.

It also has the advantage that it can be easily implemented by simply selecting the type of gas without significantly changing the conventional process.

FIG. 4 is a process sectional view for explaining the second embodiment method of the present invention. This embodiment is an example in which a flattened wiring that also serves as a filler for the opening is formed on a base having a deep opening.

First, as shown in Figure 4(a), p-type (
100) An arsenic (As) doped n layer 42 is formed on the surface of a Si substrate 41, and an S L layer of about 1.3 μm is formed on this layer.
021143 is formed by LP-CVD method. continue,
A diameter of 0.5 mm is placed at a desired position on the Si02 film 43 by RIE.
An opening 44 of μm is provided.

Next, the partial pressures o, t'
H2 with RORR 1 partial pressure 0.05 Torr TiC NO4
of.

Introducing NH at a partial pressure of 0.08 Torr, Fig. 4(b)
As shown in FIG. 3, about 500 TiN films (metal nitride layers) 45 are deposited on the entire surface. Next, the substrate temperature was set to 400°C,
Partial pressure 0.173Torr and H2 at 2partial pressure 0.013Torr
WF6 is introduced into SiH4 at a partial pressure of 0.085 Torr, and about 300 W films (metal films) 46 are deposited on the TiNJli 45.

Then, H2 with a partial pressure of 0.272 Torr and a partial pressure of 0.03
Torr's WF6 is introduced to deposit about 2000 W films 47 as shown in FIG. 4(C). At this time, the W film 4
Since the base layer 7 is the W film 46, it can be formed with good reproducibility without adding SiH. Next, as shown in FIG. 4(d), the W film 47° 46 and the TLN film 4 were
5 is selectively etched to form a wiring pattern.

In this way, in the method of this embodiment, SiH3 is first deposited on TiN.
After introducing H2 and WF6 containing H2 and WF6 and growing a W film by SiH4 reduction, a W film is grown by H2 reduction of only H2 and WF6. The reason for the two-step growth is that the growth rate is high in SiH4 reduction, so the concentration of reactant gas is insufficient in the opening with an aspect ratio of 2.6, and the growth rate in the opening is slower than in the flat area. This is supplemented by H2 reduction with excellent coverage. That is, after stable growth of W film on the TiN surface by SiH4 reduction, W film is grown by H2 reduction.
The film is made thicker. When using H2 reduction, TiN
When used directly on the surface, 0 to 48 people/w depending on the surface condition
The growth rate is 1n, but if a W film is formed on TiN, a stable growth rate of 150 people/inch can be obtained. Therefore, the W film 46° 47 can be embedded in the opening 44 having a large aspect ratio with good step coverage.
It is extremely effective in forming wiring layers.

FIG. 5 is a process sectional view for explaining the third embodiment method of the present invention. This embodiment is an example in which a selective CVD method is used to fill the opening with a conductive film.

First, as shown in Figure 5(a), p-type (
100) n'' by As doping on the surface of the Si substrate 51
Wir 52 is formed, and TiN is deposited on it by sputtering.
The film was deposited and heated in an NH3 atmosphere at 700°C for 30
A TiSi2 film 53 of 0 and a TiN film (metal nitride layer) 54 of 1000 are formed. Next, TiN film 5
An insulating film 55 having a height of 1.3 μm is formed on the film 4 . This insulating film 55 is made of S
It consists of two layers: an i02 film and a 0.5 μm BPSG film laminated. Subsequently, an opening 56 with a diameter of 0.5 μm is formed in the insulating film 55.

Then, at a substrate temperature of 400°C, a partial pressure of 0.171 Tor
H2 at r and SiH4 at 0.013 Torr and 0.08
By performing the deposition for 5 minutes in a CVD reactor in which 5 Torr of WF6 was introduced, W was deposited as shown in Fig. 5(b).
A film (metal film) 57 is selectively formed within the opening 56 .

Note that at this time, the W film does not grow on the insulating film in the flat portion, and the step coverage is not a problem because the W film grows from the bottom.

FIG. 6 is a process sectional view for explaining a fourth embodiment of the method of the present invention. In this example, in order to reliably prevent the reaction between the metal film and the St substrate, the metal nitride film between them is made to contain excess nitrogen.

First, as shown in Figure 6(a), p
Approximately 6,000 element isolation oxide films 62 are formed on a type (100) St substrate 61. Subsequently, a part of the element formation region 1015 (11-
2 ions were implanted, heat treatment was performed at 950°C for 60 minutes, and n
A + type dispersed layer 63 was formed. Next, as shown in FIG. 6(b), about 0.3 μn of Si0 is deposited on the entire surface by LP-CVD method.
Two films 64 were formed, and a contact hole 64 having a size of about 7,000 to 8,000 people was opened. In addition, As was ion-implanted again into the contact part at 30 KeV, and heat treatment was performed at 1000°C for 15 seconds to form the n-layer 6
3' was formed.

Next, 100 Ti films were sputter-deposited using argon on the substrate shown in FIG. By sputtering a Ti target at
000 TiN) (film (metal nitride layer) 66 is formed. At this time, X is larger than 1. Then, 1O%
After converting all of the 100 Ti to Ti512 by heat treatment at 700°C for 30 minutes in a hydrogen + nitrogen mixed gas, an AJ of 0°8 μm was applied to the entire surface as shown in Figure 6(d). A film (metal film) 67 is deposited.

Thereafter, the A film 67 is patterned and sintered at 450° C. for 30 minutes in a 10% hydrogen+nitrogen mixed gas.

In this embodiment, as shown in FIG. 7, the N/Ti ratio of the TiNx film 66 is 0.2 or less than 1 (X≧1).
Junction leakage current of μm can be significantly reduced.

For a junction area of 200X 500μm2, N/T
When the i ratio is 0.9 or less, it is 1O-8 to 1O-7A (when a voltage of 5V is applied), whereas when the N/Ti ratio is 1.1, it is 10-''A, and when it is 1.2 or more, it is 1O- 13A and AA'
As a result of suppressing the /St reaction, a significant improvement in junction leakage characteristics was observed.

Also, if W is used instead of A using the same method, 950
When the N/Ti ratio is 1, the silicidation rate of W at ℃ is
In terms of thickness, it is 10 people/win, but N/T
When the 1 ratio was 1.2, it decreased to 0.2 to 0.5 person/ll1n, and the reaction barrier effect was significantly improved.

Thus, according to the method of this embodiment, the TiN film 66 interposed between the base SL substrate 61 and the A film 67 serving as the wiring layer.
By making nitrogen excessive, diffusion of AI or St at the interface with the A film 67 and the grain boundaries in the TiN film 6 is suppressed, and the thermal stability of the A, ff/Si structure is improved even at higher temperatures. can be retained. In other words, the reaction barrier effect of the TiN film 66 can be enhanced, and good contact characteristics and good pn junction characteristics can be obtained. Therefore, low resistance wiring can be formed with high reliability, and it is also effective for increasing the density and integration of semiconductor devices.

Note that the present invention is not limited to the methods of each embodiment described above. For example, in the first to third embodiments, the metal nitride layer is not limited to TiN, but may include Zr, Hf, N
Nitrides such as b, Ta, Mo, and W may also be used. Furthermore, MoF6 can be used instead of WF6 as the metal halide gas for forming the metal film.

Further, as the metal film disposed between the metal nitride layer and the underlying substrate, other metal silicides, A,
It is also possible to use simple metals such as t' and W.

In addition to Sin4, hydrogen-silicon compounds include SiH6,
SiHB may also be used. Furthermore, the amount of hydrogen-silicon compound added can be changed as appropriate depending on specifications.

Furthermore, in the fourth embodiment, the metal film is not limited to A, W, etc., but may be Cu, Ag, or Au.

It may be a metal mainly composed of Pt, Pd, Ni, Mo, or Cr. Further, the metal of the metal nitride layer is not limited to Ti, but may be any metal containing Ti, Zr, Hf, Ta, or Nb as a main component. In addition, various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] As detailed above, according to the present invention, in the CVD method, by using a mixed gas of a metal halide compound gas and a hydrogen gas containing a silicon-hydrogen compound gas, a metal nitride layer can be coated. A low resistance metal film can be formed with good reproducibility in a short time and with good step coverage. Therefore, it is possible to improve the reliability of the wiring layer and the throughput of the semiconductor device. In addition, by forming the metal nitride layer with an excess of nitrogen, it is possible to reliably prevent the reaction between the metal film and the underlying substrate, making it possible to realize a highly reliable metal/Si contact. is enormous.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the manufacturing process of a semiconductor device according to the method of the first embodiment of the present invention, FIG. 2 is a schematic configuration diagram showing the CVD equipment used in the above embodiment, and FIG. 3 is a A characteristic diagram showing changes in wl deposition rate, FIG. 4 is a process cross-sectional view for explaining the method of the second embodiment, and FIG.
6 is a process cross-sectional view for explaining the method of the fourth example, and FIG. 7 is a characteristic diagram showing changes in junction leakage current with respect to N/Ti ratio. It is. 11.41.51...St substrate, 12,43°55.
...Si02 film (insulating film), 13,45.54...
TiNl1i (metal nitride layer), 14,46,47°57-W film (metal film), 42*52...n
Ten layers, 44.56...opening, 53...T i S
i 2 @. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 2 Figure 5 Figure 3 Figure 6 Figure 7

Claims (9)

[Claims] (1) In a method for manufacturing a semiconductor device that includes a step of forming a metal film on a semiconductor substrate via a metal nitride layer, a mixed gas of a metal halide gas and a hydrogen gas containing a silicon-hydrogen compound gas is used. A method of manufacturing a semiconductor device, characterized in that the metal film is deposited on the metal nitride layer by a chemical vapor deposition method. (2) The metal of the metal nitride layer is Ti, Zr, Hf,
2. The method of manufacturing a semiconductor device according to claim 1, wherein the material is Nb, Ta, Mo, or W. (3) The metal halide gas is WF_6 or M
2. The method of manufacturing a semiconductor device according to claim 1, wherein the semiconductor device is oF_6. (4) The silicon-hydrogen compound gas is SiH_4, Si
The method for manufacturing a semiconductor device according to claim 1, wherein the semiconductor device is _2H_6 or Si_3H_8. (5) The method of manufacturing a semiconductor device according to claim 1, wherein the semiconductor substrate has a diffusion layer, a metal film, or an insulating film formed on its surface. (6) In a method for manufacturing a semiconductor device including a step of forming a metal film on a semiconductor substrate via a metal nitride layer, the metal nitride layer is formed such that the initial average composition is between the metal and nitrogen of the metal nitride. A method for manufacturing a semiconductor device, characterized in that the metal nitride is formed so that the nitrogen component is in excess of that of the metal nitride containing the highest nitrogen component. (7) The method of manufacturing a semiconductor device according to claim 6, wherein the metal film has a smaller reduction in free energy due to nitridation than the metal of the metal nitride layer. (8) The metal film may include Al, Cu, Ag, Au, Pt,
7. The method of manufacturing a semiconductor device according to claim 6, wherein the metal is mainly Pd, Ni, W, Mo, or Cr. (9) The metal of the metal nitride layer is Ti, Zr, Hf,
7. The method of manufacturing a semiconductor device according to claim 6, wherein the metal is mainly Ta or Nb.