JP2704120B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to embedding aluminum in fine via holes and grooves in a wiring forming process using aluminum (Al).

[0002]

2. Description of the Related Art Conventionally, in a method of manufacturing a semiconductor device, a high melting point metal or a high melting point metal compound is deposited in a via hole on an insulating film by a sputtering method, and a wiring is formed on the deposited high melting point metal or high melting point metal compound. Aluminum, which is a film, is deposited by a sputtering method.

However, LSI (Large Scale Integrated Circuit)
As the integration of silicon increases, the aspect ratio of via holes and trenches increases, and aluminum cannot be embedded in via holes and trenches by sputtering.
VD (Chemical Vapor Deposit)
Attempts have been made to embed aluminum by the ion (vapor phase chemical growth) method. Here, the aspect ratio indicates the ratio of the thickness of the integrated circuit board to the diameter of the via hole or groove.

[0004] "Deep Submicron Com
tact Hole Filling by Al C
VD at Low Temperature "(K.M.
Sugai, et al. , Electrochemi
cal Society, Extended Abst
tracts, Volume 93-1; 482,4
83) describes a method in which a base adhesion layer TiN, which is a high melting point metal compound, is deposited by a collimator sputtering method, and aluminum is deposited thereon by a CVD method.

[0005] In this method, 0.3 μm in diameter is determined by experiments.
It has been confirmed that aluminum is buried in a via hole having an m and aspect ratio of 2.7. Note that the collimator sputtering method is a method in which a mesh is arranged between a target and a substrate, and material particles whose movement direction is mainly perpendicular to the substrate surface are deposited on the substrate.

[0006] Japanese Patent Application Laid-Open No. 5-93273 discloses that
CV after exposing SiO ₂ substrate to organic titanium gas atmosphere
It is disclosed that an aluminum film having a smooth surface shape can be obtained by forming an aluminum film by Method D.

[0007]

In the above-mentioned conventional method for manufacturing a semiconductor device, aluminum is deposited by a collimator sputtering method and an aluminum CVD method. However, in the collimator sputtering method, the diameter is 0.25 μm and the aspect ratio is 3 In the case of embedding aluminum into fine via holes of 0.3 or more, it has been confirmed from experimental results that aluminum cannot be embedded inside the via holes.

[0008] Therefore, in the above-mentioned method, since a disconnection occurs in a wiring having a via hole with a high aspect ratio, there is a problem that the yield of the semiconductor device is reduced and the productivity is reduced.

In the case where aluminum is formed by a CVD method after exposing a silicon oxide (SiO ₂ ) substrate to an organic titanium gas atmosphere, aluminum can be formed in a fine via hole having a diameter of 0.3 μm or less. Since pure Al is deposited at that time, electromigration of wiring is performed.
on) The durability is low, and the reliability of the semiconductor device is significantly reduced.

It is an object of the present invention to provide a method of manufacturing a semiconductor device which can solve the above-mentioned problems, fill a fine via hole with aluminum, and improve the reliability of the semiconductor device. is there.

[0011]

According to the present invention, there is provided a method of manufacturing a semiconductor device, comprising the steps of: depositing an insulating film on a conductive layer on a semiconductor substrate; depositing a refractory metal film on the insulating film; forming a through hole for connection to the conductive layer on the insulating film and the refractory metal film, the insulation and曝the semiconductor substrate on which the through holes are formed in the titanium compound gas atmosphere containing no halogen Film and the refractory metal film
A step of adsorbing the titanium compound gas on each of the exposed surfaces ,
The titanium compound gas is adsorbed on the semiconductor substrate.
Forming an aluminum thin film on the separated portion by a chemical vapor deposition method.

[0012]

In the Al-CVD method, many small islands are formed in the early stage of growth, and they gradually fuse to form a film. Moreover,
It has been found that the minimum thickness of the continuous film becomes the minimum radius of the via hole in which the film can be embedded.

Since CVD utilizes a chemical reaction on the surface of a substrate as a raw material, the density and size of islands formed differ depending on the surface condition of the substrate, and as a result, the limit of embedding varies depending on the surface condition of the substrate. It is expected that.

On the other hand, from the viewpoint of improving the reliability of the Al wiring, it is necessary to form an aluminum film on the high melting point metal layer or on the high melting point metal compound. Therefore, Ti and Ti
When N or TiW was exposed to tetrakisdimethylaminotitanium and an aluminum film was formed thereon, an aluminum film having a minimum thickness of 1400 ° was deposited.

On the other hand, silicon oxide (SiO ₂ )
The substrate was exposed to tetrakisdimethylaminotitanium, and an aluminum film was formed thereon.
A 0 ° aluminum film was deposited.

Therefore, it is impossible to embed aluminum in a via hole having a diameter of 0.28 μm or less on Ti, TiN, or TiW exposed to tetrakisdimethylaminotitanium, and a silicon oxide substrate exposed to tetrakisdimethylaminotitanium. 0.1 above
It was found that aluminum could be buried up to the via hole of μm.

As described above, it has been newly found that aluminum can be embedded in a via hole in a fine via hole having a diameter of 0.28 μm or less by exposing the sidewall of the via hole to SiO ₂ and exposing it to a titanium compound gas.

Therefore, in the present invention, in order to simultaneously embed aluminum in a fine via hole and achieve high reliability of wiring, a high melting point metal or a high melting point metal compound is formed on SiO ₂ before opening a connection via hole. Is deposited on

Thereafter, the side wall of the via hole for connection can be made of SiO _{2 by} etching the high melting point metal or the high melting point metal compound together with SiO ₂ . Further, a structure for depositing a high melting point metal is formed in order to enhance the reliability in places other than the connection via holes.

Thereafter, the substrate having the above-described structure is exposed to a titanium compound gas atmosphere, and aluminum is deposited by a CVD method, thereby enabling fine via holes to be embedded and highly reliable wiring.

[0021]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a manufacturing process according to an embodiment of the present invention. FIG. 1 (a) shows T, which is a refractory metal compound.
4 shows a process of depositing iN on SiO ₂ which is an insulating film,
FIG. 1B shows a step of forming a via hole, and FIG.
FIG. 1C shows a process in which tetrakisdimethylaminotitanium is adsorbed on TiN and SiO ₂ , and FIG. 1D shows a process in which an aluminum wiring is formed.

In these figures, 1 is a silicon substrate, and 2 and 6 are silicon oxide (SiO 2) on the silicon substrate 1.
₂ ) film, 3 is titanium (Ti), 4 and 7 are TiN, 5 is an aluminum (Al) film as a conductive layer, 8 is a through hole for a via hole, 9 is tetrakisdimethylaminotitanium, 10
Indicates an aluminum (Al) layer.

Referring to FIG. 1, embedding of aluminum into fine via holes and grooves in a wiring forming process using aluminum according to one embodiment of the present invention will be described.

First, a silicon oxide film 2 is deposited on a silicon substrate 1 to a thickness of about 500 nm, titanium 3 is deposited on the silicon oxide film 2 to a thickness of about 100 nm, and TiN 4 is deposited to a thickness of about 1 nm.
Deposit 00 nm.

Further, an aluminum film 5 is further
Then, a part of the titanium 3, TiN 4 and aluminum film 5 is etched, and a silicon oxide film 6 is deposited thereon as an insulating film to a thickness of about 2 μm, and TiN is deposited thereon.
7 is deposited to a thickness of about 100 nm (see FIG. 1A).

Thereafter, dry etching is performed on the substrate in the above-described state, and a through hole 8 for a via hole is formed in the silicon oxide film 6 and the TiN 7 to establish conduction with the aluminum film 5 (FIG. 1B). reference].

The substrate having the through holes 8 is placed in a tetrakisdimethylaminotitanium atmosphere at 1 mTorr for 5 mi at room temperature.
Then, tetrakisdimethylaminotitanium 9 is adsorbed to the exposed TiN 7 and the silicon oxide film 6 on the side walls of the through holes 8 (see FIG. 1C).

The substrate on which the tetrakisdimethylaminotitanium 9 has been adsorbed has an aluminum layer 10 formed thereon by CVD.
Is deposited. The deposition conditions at this time are to use dimethyl aluminum hydride as a raw material, deposit the aluminum layer 10 at a deposition temperature of 160 ° C. and a pressure of 1 Torr (see FIG. 1D).

As a result, since the high melting point metal and the high melting point metal compound were not formed on the side wall of the through hole 8 for the via hole, aluminum was introduced into the through hole 8 for the via hole having a diameter of 0.1 μm and an aspect ratio of 6. Embedding can be realized.

In the above-described method, since the aluminum buried in the via hole is deposited also on the TiN 7, the electromigration resistance can be improved as compared with the conventional example, and a semiconductor device having high reliability and a high yield can be obtained. it can.

Before opening a via hole, TiN 7 deposited on silicon oxide film 6 as an insulating film is replaced with Ti or Ti.
The same effect as described above can be obtained with other refractory metals or refractory metal compounds such as W.

Further, the temperature, pressure, and time for exposing the substrate having the through hole 8 to a tetrakisdimethylaminotitanium atmosphere are determined by TiN 7 and the silicon oxide film 6 on the side wall of the through hole 8.
Any condition may be used as long as the condition allows tetrakisdimethylaminotitanium 9 to be adsorbed, and the condition is not particularly specified.

In the above method, the film forming conditions for depositing the aluminum layer 10 by the CVD method are specified, but the same effects can be obtained under other conditions. For example, trimethylamine alane or triisobutylaluminum is used as a raw material, a film forming temperature is set to 70 ° C. to 280 ° C., and a pressure is set to 0.1 to 20 ° C.
Even if the pressure is set to Torr, the aluminum layer 10 can be deposited.

In the above method, the pretreatment with a halogen-free titanium compound gas may be carried out by using tetrakisdiethylaminotitanium, dicyclopentadienyl azide, bisdimethylaminodicyclopentadienyltitanium, or tetratrimethylsilylmethyltitanium. Even in the case where one of the atmospheres is used and tetrakisdiethylaminotitanium is adsorbed on the TiN 7 and the silicon oxide film 6 on the side wall of the through hole 8, the improvement of the embedding of aluminum into the through hole 8 is confirmed by the experiment in the same manner as described above. .

The pretreatment with a halogen-free titanium compound gas prevents corrosion of the aluminum thin film due to residual chlorine when a halogen-containing titanium compound gas is used.

As described above, TiN 7 is deposited on the silicon oxide film 6 before opening the through hole 8 for a via hole for establishing conduction with the aluminum film 5, and the through hole 8 is formed in the silicon oxide film 6 and TiN 7. After opening, the tetrakisdimethylaminotitanium 9 is adsorbed on the TiN 7 and the silicon oxide film 6 on the side wall of the through hole 8, and then an aluminum layer 10 is deposited by a CVD method. Embedding and film formation of aluminum on the high melting point metal film in the wiring portion can be realized. Therefore, a semiconductor device with high yield and high reliability can be obtained.

[0038]

As described above, according to the present invention, an insulating film is deposited on a conductive layer on a semiconductor substrate, and then a refractory metal film is deposited. After forming a through hole for connection, the semiconductor substrate is exposed to a halogen-free titanium compound gas atmosphere to deposit titanium atoms on the exposed surfaces of the insulating film and the refractory metal film, respectively. By forming a thin film, fine via holes can be filled with aluminum,
There is an effect that the reliability of the semiconductor device can be improved.

[Brief description of the drawings]

1A is a diagram showing a process of depositing a high melting point metal compound, TiN, on an insulating film of SiO ₂ , FIG. 1B is a diagram showing a process of forming a via hole, and FIG. FIG. 3D is a diagram illustrating a process of adsorbing tetrakisdimethylaminotitanium to SiO ₂ , and FIG. 4D is a diagram illustrating a process of forming an aluminum wiring.

[Explanation of symbols]

 Reference Signs List 1 silicon substrate 2, 6 silicon oxide film 3 titanium 4, 7 TiN 5 aluminum film 8 through hole for via hole 9 tetrakisdimethylaminotitanium 10 aluminum layer

Continued on the front page (72) Inventor Akiko Kobayashi 5-8-1, Yotsuya, Fuchu-shi, Tokyo Nidec Anelva Co., Ltd. (72) Inventor Tadaaki Yago 5-1 Sokai-cho, Niihama-shi, Ehime Prefecture Sumitomo Chemical Industries, Ltd. (72) Inventor Hideko Kadokura 5-1, Sokai-cho, Niihama-shi, Ehime Sumitomo Chemical Industries, Ltd. (56) References JP-A-6-224309 (JP, A) JP-A-6-224305 (JP) JP-A-1-243551 (JP, A) JP-A-5-93273 (JP, A) JP-A-7-193064 (JP, A)

Claims (5)

(57) [Claims] A step of depositing an insulating film on a conductive layer on a semiconductor substrate; a step of depositing a refractory metal film on the insulating film; and a step of depositing the conductive layer on the insulating film and the refractory metal film. forming a through hole for connecting said insulating film and the refractory metal film the semiconductor substrate on which the through holes are formed in曝the titanium compound gas atmosphere containing no halogen
A step of adsorbing the titanium compound gas on each of the exposed surfaces ,
The titanium compound gas is adsorbed on the semiconductor substrate.
Forming an aluminum thin film on the separated portion by a chemical vapor deposition method. 2. The method according to claim 1, wherein the insulating film is made of a silicon oxide film. 3. The halogen-free titanium compound gas is selected from the group consisting of tetrakisdimethylaminotitanium, tetrakisdiethylaminotitanium, dicyclopentadienyl azide, bisdimethylaminodicyclopentadienyltitanium and tetratrimethylsilylmethyltitanium. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the method comprises one. 4. The method for manufacturing a semiconductor device according to claim 1, wherein said high melting point metal film is made of one of a high melting point metal and a high melting point metal compound. 5. The refractory metal film is made of Ti, TiN and T
4. The method of manufacturing a semiconductor device according to claim 1, wherein the method comprises any one of iW.