JP2966414B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in the following order.

A. Industrial application fields B. Summary of the invention C. Prior art [Fig. 2] D. Problems to be solved by the invention E. Means to solve the problems F. Function G. Example [No. FIG. 1] H. Effects of the Invention (A. Industrial Application Field) The present invention provides a method of manufacturing a semiconductor device, particularly, a connection between a semiconductor region and a wiring film through a minute contact hole without interposing a large resistance. And a method of manufacturing a semiconductor device.

(B. Summary of the Invention) The present invention relates to a method of manufacturing a semiconductor device, comprising the steps of: forming a semiconductor substrate before forming a contact hole in order to reduce the resistance inside a minute contact hole connecting the semiconductor region and the wiring film; A refractory metal film such as titanium is formed on the surface of the portion where the contact hole is to be formed, and the surface is nitrided to form a barrier metal. After the contact hole is formed, the contact hole is filled with polycrystalline silicon. Next, a high melting point metal film such as titanium is formed, and the polycrystalline silicon in the contact hole is used as a silicide film of the high melting point metal film, and then a surface portion of the silicide film is nitrided to form a barrier metal. Thereafter, a wiring film is formed.

(C. Prior Art) [FIG. 2] Conventionally, a connection between a semiconductor region formed on a surface portion of a semiconductor substrate and an aluminum wiring film formed on an insulating film on the semiconductor substrate is made by forming a wiring film. Through an aluminum film that fills a contact hole of an insulating film by vapor deposition or sputtering of aluminum.

By the way, in a semiconductor integrated circuit, a demand for high integration is strongly demanded, and the miniaturization of a semiconductor element is progressing. Then, as the semiconductor element becomes finer, the contact hole becomes finer, and it is required that the diameter is 0.5 μm or smaller. By the way, when the diameter of the contact hole becomes 0.5 μm or less, it is impossible to make a good contact with the conventional general technique of forming an aluminum wiring film by sputtering and filling the contact hole with the aluminum wiring film. Because, according to the sputtering of aluminum, the diameter
This is because aluminum does not enter the contact hole of 0.5 μm or less at all, and the aluminum wiring film is disconnected.

This is because, as in the technique described in JP-B-58-46052, titanium or titanium is deposited or sputtered in a contact hole in order to prevent titanium from reacting with an aluminum wiring film and a semiconductor region. It also occurs in the case of forming. In addition, JP
A titanium (Ti) film is formed in a contact hole as in the technique described in
i) The same applies to the case where a titanium silicide (TiSi ₂ ) film is formed as a barrier metal in a contact hole by forming a film. Japanese Patent Application Laid-Open Nos. 51-9957 and 61-78163 also disclose a technique for forming a high melting point metal such as platinum or molybdenum in a contact hole. If it is less than 0.5, disconnection tends to occur.

Therefore, it is conceivable to fill the contact hole with silicon. That is, if polycrystalline silicon is formed by CVD, the step coverage is good, so the diameter is 0.5 μm.
This is because silicon Si can also be present in a small contact hole of m or less, and the silicon Si can connect between the aluminum wiring film and the semiconductor region.

2A and 2B are cross-sectional views showing such a manufacturing method (conventional example) in the order of steps.

(A) After forming a semiconductor region b on the surface of a semiconductor substrate a, an interlayer insulating film (PSG) c is formed, a contact hole d is formed in the insulating film c, and then a polycrystalline silicon film e is formed.
Is formed by CVD, and thereafter, the insulating film c is etched back so that the polycrystalline silicon film e remains only in the contact hole d. FIG. 2A shows the state after the etch back. Note that f is a channel stopper, g
Is a field insulating film formed by selective oxidation.

(B) Thereafter, an aluminum wiring film h is formed as shown in FIG. A technique of filling the contact hole d with silicon e and making contact between the semiconductor region b and the wiring film h through the silicon e is disclosed in
It is also introduced in -77364.

(D. Problems to be Solved by the Invention) However, since silicon Si has a very high specific resistance (about 800 μΩcm in the case of polycrystalline silicon) as compared with a wiring material such as aluminum, silicon is connected to a semiconductor region. There is a problem that the wiring resistance, which is provided between the films, increases.

The present invention has been made in order to solve such a problem, and even if the contact hole is fine, the step between the semiconductor region and the wiring film is not generated without increasing the contact resistance without increasing the step resistance. The purpose is to make sure that contact can be made.

(E. Means for Solving the Problems) In order to solve the above problems, the method for manufacturing a semiconductor device of the present invention has a semiconductor region on a surface portion and is selectively formed so that the semiconductor region is exposed. The first insulating film, including the first insulating film, on the silicon semiconductor substrate covered with the first insulating film.
Forming a high-melting-point metal film over the entire surface, annealing the portion of the first high-melting-point metal film in contact with the semiconductor region in a self-aligned manner, Using a difference in etching rate between the silicided portion and the non-silicided portion of the film to remove the non-silicided portion in a self-aligned manner by etching, and to form the silicide by annealing in a nitrogen atmosphere. Nitriding the first refractory metal film surface, forming a second insulating film over the entire surface of the silicon semiconductor substrate, and selectively etching the second and the insulating film. Forming a contact hole by the method, filling the contact hole with polycrystalline silicon, and forming a contact hole filled with the polycrystalline silicon. The second on the second insulating film including upper
Forming a high-melting point metal film and annealing the polycrystalline silicon in the contact hole into a second high-melting-point metal silicide film by annealing in an inert gas atmosphere; Removing the unreacted silicide film portion of the second refractory metal by self-alignment by etching utilizing a difference in etching rate between the silicide film portion and the non-silicide film portion; Forming a barrier metal comprising a nitride film of a melting point metal on the surface of the silicide film by annealing in a nitrogen atmosphere in a self-aligning manner; And forming a wiring film to be connected.

(F. Function) According to the method of manufacturing a semiconductor device of the present invention, the contact hole of the insulating film is filled with polycrystalline silicon by, for example, CVD. Can be filled. Therefore, the possibility of disconnection can be eliminated.

Since the polycrystalline silicon in the contact hole is made of silicide of a high melting point metal, the resistance in the contact hole is significantly reduced. Therefore, there is no possibility that the wiring resistance is unnecessarily increased in the contact hole, which can greatly contribute to miniaturization of the semiconductor element of the semiconductor integrated circuit.

In addition, the removal of the refractory metal film is performed by self-aligned etching utilizing a difference in etching rate between the silicide film and the refractory metal film, so that it is troublesome to form, expose, and develop a photoresist film. This can be done without performing photoetching. Therefore, the high melting point metal film can be easily removed.

Further, since a barrier metal made of the silicide nitride is formed in a self-aligned manner on the surface of the silicide film by a nitriding treatment, the intrusion of the wiring film material into the semiconductor region can be prevented without increasing the number of steps. be able to.

(G. Embodiment) [FIG. 1] Hereinafter, a method for manufacturing a semiconductor device of the present invention will be described in detail with reference to illustrated embodiments.

1A to 1M are cross-sectional views showing one embodiment of a method for manufacturing a semiconductor device of the present invention in the order of steps.

(A) After a channel stopper 2 is formed on the surface of a silicon semiconductor substrate 1, a field insulating film 3 is formed by selective oxidation.
Is formed, and then a semiconductor region 4 is formed by doping impurities on the surface of the semiconductor substrate 1. Thereafter, a titanium film (thickness: 800 °) 5 which is a refractory metal is formed on the surface of the semiconductor substrate 1. . Therefore, the surface of the semiconductor region 4 is covered with the titanium film 5. FIG. 1A shows a state after the titanium film 5 is formed.

(B) Next, IR annealing is performed at a temperature of 600 ° C. for 30 seconds in an argon Ar atmosphere. Then, the semiconductor region 4 of the titanium film 5
The upper portion reacts with silicon in the semiconductor region 4 to form a titanium silicide (TiSi) film 6. FIG. 1B shows a state after the completion of annealing.

(C) Next, as shown in FIG. 1C, the titanium film 5 is removed using, for example, ammonia peroxide as an etching solution. Note that the titanium silicide film 6 remains.

(D) Next, IR annealing is performed at a temperature of 800 ° C. for 30 seconds in a nitrogen (N) atmosphere. Then, titanium silicide (TiS
i) The film 6 is transformed into a titanium silicide film 7 made of TiSi ₂ , and the surface of the film 6 is made of titanium nitride (TiN).
A film 8 is formed. FIG. 1 (D) shows the state after the aryl treatment.

The titanium silicide film 7 serves to improve the contact with the semiconductor region 4 and reduce the contact resistance, and the titanium nitride film 8 prevents the metal constituting the wiring film from entering the semiconductor region 4. It acts as a barrier metal.

(E) Next, as shown in FIG. 1E, an interlayer insulating film 9 made of PSG is formed.

(F) Next, as shown in FIG. 2F, a contact hole for taking out an electrode of the semiconductor region 4 in the insulating film 9.
10 is formed by RIE. This contact hole 10 has a very small diameter of, for example, 0.5 μm.

(G) Next, as shown in FIG. 3G, a polycrystalline silicon film (thickness: 4000 Å) 11 is formed on the entire surface of the semiconductor substrate by CVD. When polycrystalline silicon is grown by CVD, the step coverage is good, so that the polycrystalline silicon also penetrates into the minute contact holes 10 and the contact holes 10 can be reliably filled with polycrystalline silicon. Further, the deposition rate is high, which is preferable in terms of productivity.

(H) Next, the polycrystalline silicon film 11 is etched back to
As shown in FIG. 1H, the polycrystalline silicon film 11 is left only in the contact hole 10.

(I) Next, as shown in FIG. 1I, a titanium film (2000 °) 12 is formed on the surface of the semiconductor substrate 1. This titanium film 12 is formed to turn the polycrystalline silicon film 11 in the contact hole 10 into a titanium silicide film later.

(J) Next, at a temperature of 600 ° C. in an argon (Ar) atmosphere,
Perform IR annealing for 0 seconds. Then, the polycrystalline silicon film 11 in the contact hole 10 reacts with the titanium film 12 to become a titanium silicide film 13 as shown in FIG. 1 (J). Therefore, the resistance inside the contact hole 10 becomes very small. This is because the specific resistance of polycrystalline silicon is 800 μΩcm as described above, while titanium silicide (TiS
This is because the specific resistance of i) is as very small as 10 μΩcm (more than 1%). As a result, the wiring resistance can be reduced.

(K) Next, as shown in FIG. 1 (K), a portion of the titanium film 12 which has not reacted with the polycrystalline silicon film 11 is removed by etching using ammonia peroxide as an etching solution.

(L) Next, by performing IR annealing at a temperature of 800 ° C. for 30 seconds in a nitrogen (N) atmosphere, titanium silicide (TiSi)
The film 13 is formed into a TiSi ₂ film 14 and a titanium nitride (TiN) film 15 is formed on the surface thereof in a self-aligned manner. The titanium nitride film 15 functions as a barrier metal for preventing aluminum of a wiring film to be formed later from entering the semiconductor region. FIG. 1 (L) shows a state after the completion of the annealing.

(M) Thereafter, an aluminum wiring film 16 is formed as shown in FIG. This wiring film 16 is in contact hole 10
It is connected to the semiconductor region 4 via the titanium nitride film 15 and the titanium silicide film 14 therein and the titanium nitride film 8 and the titanium silicide film 7 on the surface of the semiconductor region 4.

According to such a method of manufacturing a semiconductor device, since the inside of the contact hole 10 is filled with polycrystalline silicon by growing polycrystalline silicon by CVD, even if the contact hole 10 is very fine, 10 can be filled with a conductive material.
Therefore, the possibility of disconnection between the wiring film 16 and the semiconductor region 4 can be eliminated.

The polycrystalline silicon 11 itself filling the inside of the contact hole 10 cannot be said to have a low specific resistance.
The polycrystalline silicon film 11 inside is titanium silicide (TiSi ₂ )
The film is changed to a film 13, and since titanium silicide (TiSi ₂ ) has a very small specific resistance, the wiring resistance hardly increases.

Therefore, the connection between the wiring film 16 and the semiconductor region 4 through the minute contact hole 10 can be reliably performed without increasing the wiring resistance.

Since the titanium nitride films 15 and 8 prevent the aluminum constituting the wiring film 16 from entering the semiconductor region 4, it is possible to effectively prevent the deterioration of the characteristics of the semiconductor element due to the entry of aluminum into the semiconductor region 4. it can.

(H. Effects of the Invention) As described above, the method of manufacturing a semiconductor device according to the present invention includes the first insulating film having a semiconductor region on a surface portion and selectively formed such that the semiconductor region is exposed. Forming a first refractory metal film entirely on the silicon semiconductor substrate covered with the first insulating film, including on the first insulating film; and annealing the first refractory metal film with the semiconductor region of the first refractory metal film. A step of self-aligning silicidation of the contacting part, and a step of utilizing the difference in etching rate between the silicided part and the non-silicided part of the first refractory metal film to remove the non-silicided part. Removing by self-alignment by etching, nitriding the surface of the silicidized first refractory metal film by annealing in a nitrogen atmosphere; Forming a contact hole by selectively etching the second insulating film, burying polycrystalline silicon in the contact hole; Forming a second refractory metal film on the second insulating film, including on the contact hole in which the polycrystalline silicon in the contact hole is filled with the second insulating film, by annealing in an inert gas atmosphere; A step of forming a silicide film of a refractory metal; and etching of the second refractory metal in a self-aligned manner by utilizing an etching rate difference between a part where the silicide film is formed and a part where the silicide film is not formed. Removing the portion of the high-melting-point metal that was not turned into a silicide film, and annealing the surface of the silicide film by annealing in a nitrogen atmosphere. At least a step of forming a barrier metal made of a nitride film of a high melting point metal and a step of forming a wiring film connected to the semiconductor region via the silicide film on the second insulating film. It is characterized by having.

Therefore, according to the method of manufacturing a semiconductor device of the present invention, polycrystalline silicon is formed in a contact hole of an insulating film by, for example, KCVD.
Therefore, even if the contact hole is fine, the inside of the contact hole can be filled with a conductive material. Therefore, the possibility of disconnection can be eliminated.

Since the polycrystalline silicon in the contact hole is made of silicide of a high melting point metal, the resistance in the contact hole is significantly reduced. Therefore, there is no possibility that the wiring resistance is unnecessarily increased in the contact hole, which can greatly contribute to miniaturization of the semiconductor element of the semiconductor integrated circuit.

In addition, the removal of the refractory metal film is performed by self-aligned etching utilizing a difference in etching rate between the silicide film and the refractory metal film, so that it is troublesome to form, expose, and develop a photoresist film. This can be done without performing photoetching. Therefore, the high melting point metal film can be easily removed.

Furthermore, since a barrier metal composed of a nitride of the silicide is formed in a self-aligned manner on the surface of the silicide film by nitrogen treatment, it is possible to prevent the wiring film material from invading the semiconductor region side without increasing the number of steps. be able to.

[Brief description of the drawings]

1A to 1M are cross-sectional views showing one embodiment of a method of manufacturing a semiconductor device according to the present invention in the order of steps, and FIGS.
(B) is sectional drawing which shows a prior art example in order of a process. DESCRIPTION OF SYMBOLS 1 ... semiconductor substrate, 2 ... insulating film, 10 ... contact hole, 11 ... polycrystalline silicon, 12 ... high melting point metal film, 16
... Wiring film.

 ────────────────────────────────────────────────── (5) References JP-A-58-3250 (JP, A) JP-A-61-137367 (JP, A) JP-A-62-104174 (JP, A)

Claims (1)

(57) [Claims] 1. A method according to claim 1, wherein the first insulating film is formed on a silicon semiconductor substrate having a semiconductor region on a surface portion and covered with a first insulating film selectively formed such that the semiconductor region is exposed. Forming a first refractory metal film entirely, including: a step of self-aligning silicidation of a portion of the first refractory metal film that contacts the semiconductor region by annealing; Using a difference in etching rate between the silicided portion and the non-silicided portion of the refractory metal film to remove the non-silicided portion in a self-aligned manner by etching, and annealing in a nitrogen atmosphere. Nitriding the surface of the silicidized first refractory metal film, forming a second insulating film over the entire surface of the silicon semiconductor substrate, and selectively forming the second insulating film. Forming a contact hole by etching the contact hole; filling the contact hole with polycrystalline silicon; and forming a second high film on the second insulating film including on the contact hole filled with the polycrystalline silicon. Forming a melting-point metal film and turning the polycrystalline silicon in the contact hole into a second refractory-metal silicide film by annealing in an inert gas atmosphere; Removing the unreacted silicide portion of the second refractory metal by self-alignment by etching utilizing the difference in etching rate between the filmed portion and the non-silicide film portion; A barrier metal consisting of a refractory metal nitride film is formed in a self-aligned manner by annealing in a nitrogen atmosphere. Forming a wiring film connected to the semiconductor region via the silicide film on the second insulating film. A method for manufacturing a semiconductor device, comprising: