JP3017810B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for forming a wiring layer.

[0002]

2. Description of the Related Art In recent years, when an impurity diffusion layer such as a source or a drain is formed on a surface of a semiconductor substrate in accordance with high integration,
An extremely shallow one such as 0.2 μm or less has been required. However, when the diffusion layer is shallow, when the electrode wiring is formed of pure aluminum (hereinafter, referred to as Al) or the like, the substrate is exposed to a high temperature during the process, and Al and silicon of the semiconductor substrate (hereinafter, referred to as Si) interdiffuse. I do. As a result, Al spikes penetrate through the diffusion layer and pn
The joint is destroyed.

Therefore, in order to prevent such destruction, it has been practiced to mix in advance Al a solid solution limit or more. However, in this case, excessive Si contained in Al may precipitate on the fine bottom of the contact hole and may cover the contact hole. Moreover, since the p-type crystal is doped with Al and has a high resistance, there is a problem that the contact resistance increases. In particular, this problem is fatal in an n-type diffusion layer.

[0004] In addition, the width of the wiring layer is reduced with the increase in integration, and the Al wiring layer is disconnected due to electromigration (hereinafter referred to as EM) or stress migration (hereinafter referred to as SM). The problem is becoming more pronounced. A trace amount of metal such as copper (Cu) is added,
M. And S. M. Is suppressed, but a sufficient suppression effect cannot be obtained.

Therefore, a barrier layer is provided at a portion where the Al wiring layer and the surface of the semiconductor substrate are in contact with each other to suppress the mutual diffusion and reaction between Al and Si. As the material of the barrier layer, a refractory metal, or a silicide or nitride film using a refractory metal or a noble metal is used. However, even when a barrier layer made of these materials is formed, the reaction between Al and the barrier layer or the reaction between the barrier layer and silicon cannot be sufficiently suppressed. For this reason, the surface of the barrier layer is oxidized to improve the barrier property. However, it is difficult to control the progress of oxidation, and it is difficult to form a stable barrier layer.

There is also a problem that the bonding characteristics deteriorate after the oxidation step. When wire bonding is performed on the electrode, the wire pulls the barrier layer below the electrode and the insulating layer thereunder. When the surface of the barrier layer is oxidized, a tensile stress acts on the barrier layer even by the oxidation, and thus, the separation may occur between the barrier layer and the insulating layer.

[0007]

As described above, according to the conventional manufacturing method, the contact resistance between the diffusion layer and the wiring layer is increased, M. And S. M. However, there is a problem that a highly reliable fine wiring layer cannot be formed.

The present invention has been made in view of the above circumstances. Even when a shallow diffusion layer is formed, a low contact resistance can be obtained with a wiring layer, and a fine wiring layer can be formed with high reliability. It is an object of the present invention to provide a method for manufacturing a semiconductor device that can be used.

[0009]

According to a method of manufacturing a semiconductor device of the present invention, a first step of forming an insulating film on a semiconductor substrate having a diffusion layer formed on a surface portion thereof; A second step of removing the upper part and opening a contact hole, and carrying the semiconductor substrate into a vacuum apparatus, depositing a high melting point metal on the insulating film and on the diffusion layer exposed at the contact hole, thereby forming a high melting point metal. A third step of forming the melting point metal film and a first high melting point metal nitride film in which the high melting point metal is nitrided are continuously formed with the semiconductor substrate placed in a vacuum apparatus, and heating is performed simultaneously. A fourth step of nitriding the portion of the refractory metal film at the interface with the first refractory metal nitride film and silicifying the portion of the refractory metal film at the interface with the diffusion layer; Of the high melting point metal nitride film Fifth forming a refractory metal nitride layer
And a sixth step of forming a wiring layer on the second refractory metal nitride film.

Here, it is preferable that at least the side wall portion of the contact hole in the refractory metal film is entirely nitrided in the fourth step.

In the fourth step, at least the portion of the bottom surface of the contact hole of the refractory metal film at the interface with the diffusion layer is silicided, and the portion at the interface with the first refractory metal nitride film is formed. Is preferably all nitrided.

In the fourth step, the rate at which the interface between the refractory metal film and the first refractory metal nitride film is nitrided depends on the rate at which the interface between the refractory metal film and the diffused layer intersects. It is better to be faster than or simultaneous to the silicidation.

As the refractory metal, for example, titanium, molybdenum, tungsten, cobalt, nickel, vanadium, and hafnium can be used.

The refractory metal film has a compressive stress of 0 to 5 ×.
Preferably, it is formed so as to be within the range of 10 ⁹ (dyn / cm ² ).

[0015]

In the refractory metal film, a portion at the interface with the diffusion layer is silicided, so that the refractory metal nitride film has a high barrier property without being oxidized, and is formed with a metal material contained in the wiring layer. Alternate diffusion with silicon in the semiconductor substrate is suppressed, and the situation where the pn junction of the diffusion layer is destroyed is avoided. In addition, since the portion of the refractory metal film on the diffusion layer is silicided, the contact resistance is reduced. In addition, since a barrier metal layer made of a high melting point metal nitride film, a high melting point metal film, and a silicide film is laid under the wiring layer, E.I. M. And S. M. Is suppressed, and the wiring life is prolonged.

Here, in the refractory metal film, at least the entire side wall portion of the contact hole is nitrided, so that the barrier property is enhanced. In addition, at least the portion of the bottom surface of the contact hole of the refractory metal film at the interface with the diffusion layer is entirely silicided, and the portion of the interface with the first refractory metal nitride film is all nitrided, so that the wiring Interdiffusion between the metal material of the layer and silicon in the semiconductor substrate is reliably prevented.

The rate at which the interface between the refractory metal film and the first refractory metal nitride film is nitrided depends on the rate at which the interface between the refractory metal film and the diffusion layer is silicided. By being faster than the speed or simultaneously, the silicon in the semiconductor substrate is prevented from being sucked out due to the silicide film being too thick.

As the refractory metal, for example, titanium, molybdenum, tungsten, cobalt, nickel, vanadium, and hafnium can be used.

The refractory metal film has a compressive stress of zero.
By being formed so as to be within the range of 5 × 10 ⁹ (dyn / cm ² ), even when wire bonding is performed on the pad, the oxide film under the pad is prevented from peeling, and the bonding characteristics are improved. improves.

[0020]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a method of manufacturing the semiconductor device according to the present embodiment step by step. As shown in FIG.
Impurity ions such as phosphorus ions (P +) and arsenic ions (As +) are implanted into the surface of the p-type semiconductor substrate 1 to form an n-type diffusion layer 2. Then, the entire surface of semiconductor substrate 1 is oxidized to form a silicon oxide film. The upper portion of the diffusion layer 2 is selectively removed from the silicon oxide film by using a photolithography method to form a silicon oxide film 3 having a contact hole 10 formed therein.

The semiconductor substrate 1 is carried into a usual sputtering apparatus. Sputtering is performed on the entire surface of the silicon oxide film 3, and titanium (Ti) is deposited to a thickness of 100 to 500 angstroms to form a titanium film 4 as shown in FIG.

Next, reactive sputtering is performed continuously with the semiconductor substrate 1 still in the sputtering apparatus, that is, without exposing the semiconductor substrate 1 to the atmosphere. This sputtering is performed in an atmosphere of argon (Ar) and nitrogen (N2), and a titanium nitride film 5 is
1 to 200 angstroms (FIG. 1).
(C)). In this case, the deposition rate is 0.5 to 1 minute.
The semiconductor substrate 1 is set as slow as 2 angstroms, and is heated to 400 to 800 degrees Celsius simultaneously with the deposition. As a result, the surface portion of the titanium film 4 that is in contact with the titanium nitride film 5 is nitrided and changes to a nitride film 6, and at the same time, the portion that is in contact with the diffusion layer 2 is silicided to form a silicide film 7. Change. Here, the diffusion layer 2
The titanium film 5 needs to be silicided or nitrided without remaining on the upper surface of the contact hole 10 and the side wall of the contact hole 10, but may remain on a field oxide film (not shown). It is necessary that the rate at which the titanium film 4 is nitrided is higher than or simultaneous with the rate at which the titanium film 4 is silicided. This is because if the silicidation is fast, the thickness of the silicide film 7 becomes too large, and silicon in the semiconductor substrate 1 is sucked out. The titanium nitride film 5 undergoes volume shrinkage due to the reaction with titanium, and as a result, has a tensile stress.

Further, reactive sputtering is performed continuously, and the titanium nitride film 8 is formed to a thickness of 500 to 2,000 angstroms at a higher volume rate (5 to 20 angstroms per minute) than when the titanium nitride film 5 is formed. Is formed. In this case, the sputtering conditions are set so that the titanium nitride film 8 has a compressive stress of about 5 × 10 ⁹ (dyn / cm ² ). By doing so, the tensile stress of the titanium nitride film 5 and the compressive stress of the titanium nitride film 8 cancel each other, and the compressive stress remaining in the titanium nitride films 5 and 8 is 0 to 5 × 10
⁹ (dyn / cm ² ).

Thereafter, aluminum, silicon, and copper (Al-Si-Cu) alloy are deposited on the entire surface of the titanium nitride film 8 by sputtering to form a wiring film having a thickness of 8000 angstroms. An ordinary photolithography method is used for the wiring film, the titanium nitride film 8, the nitride film 6, the nitride film 6, and the titanium film 4 to form a wiring film 9, a titanium nitride film 8a as shown in FIG. 5a, a nitride film 6a and a titanium film 4a are formed, and a wiring layer having a desired pattern is obtained.

As described above, in this embodiment, the wiring layer is formed of (Al-S
Wiring film 9 made of i-Cu) alloy, titanium nitride film 8
a and 5a, a nitride film 6a, and a titanium film 4a. The titanium film 4 does not remain on the surface of the diffusion layer 2 and is silicided. For this reason,
Even without performing the oxidation treatment of the titanium nitride film 5a,
Interdiffusion between Al contained in the wiring film 9 and silicon in the semiconductor substrate 1 is suppressed, and a situation where Al spikes penetrate the diffusion layer 2 and destroy the pn junction is avoided.

Further, since the silicide film 7 is formed on the diffusion layer 2, the contact resistance between the diffusion layer 2 and the wiring layer is reduced. Under the Al alloy wiring film 9, titanium nitride films 8a and 5a, a nitride film 6a,
Since the barrier metal layer made of the titanium film 4a is laid, E.I. M. Or S. M. Is suppressed,
The service life up to the disconnection is more than doubled compared to the conventional case, and high reliability is obtained. Further, since the tensile stress is relaxed between the titanium nitride film 8a and the titanium nitride film 5a, peeling between the titanium nitride film 8a and the oxide film formed under the pad is prevented, and the bonding characteristics are improved. I do.

The above-described embodiment is merely an example, and does not limit the present invention. For example, in the embodiment, the wiring film 9 is made of Al
-Si-Cu alloy, but Al-Si alloy or pure Al
May be formed. In particular, when the wiring film is formed of pure Al, the wiring resistance can be reduced. Although titanium is used as the refractory metal in the embodiment, molybdenum (Mo), tungsten (W), cobalt (C
o), other refractory metals such as nickel (Ni), vanadium (V), hafnium (Hf), tantalum (Ta) can also be used. Although the diffusion layer 2 of the embodiment is n-type,
The present invention can be similarly applied to the case of forming a p-type diffusion layer.

[0028]

As described above, according to the method of manufacturing a semiconductor device of the present invention, since the interface between the refractory metal film and the diffusion layer is silicided, the refractory metal nitride film can be used. Even if the oxidation treatment is not performed, the barrier property is high, the alternate diffusion of the metal material contained in the wiring layer and silicon in the semiconductor substrate is suppressed, and the situation where the pn junction of the diffusion layer is destroyed is avoided. In addition, since a barrier metal layer made of a high melting point metal nitride film, a high melting point metal film, and a silicide film is laid under the wiring layer, E.I. M. And S.
M. Is suppressed, the wiring life is extended, and high reliability is obtained. Further, since the portion of the high melting point metal film on the diffusion layer is silicided, the contact resistance is reduced.

[Brief description of the drawings]

FIG. 1 is an element cross-sectional view illustrating a method of manufacturing a semiconductor device according to an embodiment of the present invention for each process.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 semiconductor substrate 2 diffusion layer 3 silicon oxide film 4 titanium film 5 titanium nitride film 6 nitride film 7 silicide film 8 titanium nitride film 9 wiring film

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-235372 (JP, A) JP-A-63-84024 (JP, A) JP-A-2-119129 (JP, A) JP-A 61-840 174767 (JP, A) JP-A-4-79218 (JP, A) JP-A-4-27163 (JP, A) JP-A-3-185722 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) H01L 21/28 301 H01L 21/3205 H01L 21/768

Claims (6)

(57) [Claims] A first step of forming an insulating film on a semiconductor substrate having a diffusion layer formed on a surface thereof, and a step of forming a contact hole by removing an upper portion of the diffusion layer in the insulating film. Step 2, carrying the semiconductor substrate into a vacuum device,
A third step of depositing a refractory metal on the insulating film and on the diffusion layer exposed by the contact hole to form a refractory metal film, and placing the semiconductor substrate in the vacuum device Forming a first refractory metal nitride film in which the refractory metal is nitrided, and simultaneously heating the refractory metal film to form the first refractory metal nitride film. A fourth step of nitriding an interface portion of the first refractory metal film and siliciding an interface portion of the refractory metal film with the diffusion layer; and
A fifth step of forming a second refractory metal nitride film in which the refractory metal is nitrided, and a sixth step of forming a wiring layer on the second refractory metal nitride film A method for manufacturing a semiconductor device, comprising: 2. The method of manufacturing a semiconductor device according to claim 1, wherein, in said fourth step, at least a side wall portion of said contact hole in said refractory metal film is entirely nitrided. 3. The method according to claim 1, wherein the step (c) comprises:
2. The method of manufacturing a semiconductor device according to claim 1, wherein all of the interface with the diffusion layer is silicided, and all of the interface with the first refractory metal nitride film is nitrided. 4. In the fourth step, the rate at which an interface portion of the refractory metal film at the interface with the first refractory metal nitride film is nitrided is the diffusion rate of the refractory metal film in the refractory metal film. 4. The method of manufacturing a semiconductor device according to claim 1, wherein the speed of the silicidation at the interface with the layer is higher than or simultaneous with the speed of silicidation. 5. The high melting point metal is titanium, molybdenum,
5. The method for manufacturing a semiconductor device according to claim 1, wherein the semiconductor device is any one of tungsten, cobalt, nickel, vanadium, and hafnium. 6. The refractory metal film according to claim 1, wherein said refractory metal film is formed such that its compressive stress is in a range of 0 to 5 × 10 ⁹ (dyn / cm ² ). A method for manufacturing a semiconductor device.