JP2964185B2 - Method for forming 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 semiconductor device having a contact hole in which an Al layer or an alloy layer of Al and another metal is provided between a silicon substrate and a barrier metal, and a method of forming the same.

[0002]

2. Description of the Related Art With the advance of LSI technology, rapid densification and accompanying high speed have been achieved. This includes polycrystalline Si
The technology is largely dependent on the technology, but higher density leads to a reduction in wiring width and an increase in wiring length. Make it difficult. Silicide has a resistance about one digit smaller than that of other crystalline Si, and can suppress signal delay due to wiring resistance to a relatively small value.

As a method of forming silicide, there are a method of forming a metal on a single crystal or a polycrystalline Si to obtain a silicide by heat treatment, and a method of directly forming a silicide by a sputtering method or the like.

Conventionally, at the time of heat treatment for silicidation in a semiconductor device, a barrier metal such as titanium nitride is deposited to prevent interdiffusion between silicon and an Al wiring layer and to normally carry out a silicidation reaction. Generally, titanium nitride, titanium, and titanium tungsten are used as a barrier metal formed below the AlSi layer serving as a wiring layer.

However, in the prior art, since the barrier metal and the active region of the silicon substrate are in direct contact with each other, the impurity in the P-type diffusion region diffuses into the barrier metal, and the concentration of the diffusion region is reduced. Since a film is formed, there has been a problem that the contact resistance increases or becomes unstable.

For this reason, for example, Japanese Patent Application Laid-Open No. 63-2572
Referring to No. 69, platinum silicide is used as a metal for SBD or a contact metal, and a material having a lower barrier height than platinum, such as Al, is introduced into PtSi for silicon to lower the barrier height and heat treatment for silicidation is performed. Sometimes AlPtSi to prevent interdiffusion between silicon and Al wiring layer
After the formation of the layer, a barrier metal is deposited to normalize the silicidation reaction, thereby suppressing the formation of a silicon oxide film on the PtSi surface.

Further, between the barrier metal and the silicon substrate
A method of forming a low-efficiency TiSi layer between the barrier metal and the active region of the silicon substrate by providing the AlSi layer to suppress the deposition of silicon from the punch-through phenomenon has been taken. Generally, a Ti layer is formed between a barrier metal and a silicon substrate. In this case, however, the concentration of the P-type impurity is reduced due to the interaction between Ti and the impurity in the P-type diffusion region. Resistance from 50 to 100Ω / cm ² to several hundreds to several tens
It is also known to increase to kΩ / cm ² .

[0008]

In view of the circumstances as this [0006] The present invention provides the advantages of a conventional barrier metal is maintained, further silicide compound of Al or Al alloy between the barrier metal and the silicon substrate and its object is to provide a method of forming a semiconductor equipment provide improved contact resistance was coated with a decrease in the impurity concentration.

[0009]

[0010]

Means for Solving the Problems To achieve the above object,
Therefore, the method for forming a semiconductor of the present invention
Alternatively, a silicide compound with an Al alloy, then Ti, and a barrier metal are formed thereon, and a two-layer silicide compound is formed between the impurity diffusion region and the barrier metal.

[0011]

According to the structure in which the silicide compound with Al or Al alloy is formed between the silicon substrate and the barrier metal, an aluminum silicide layer is formed at the interface with the silicon substrate, and the aluminum silicide layer is formed on the upper surface with the interface with titanium. Is formed with a titanium silicide layer.

For this reason, the diffusion region and the wiring layer are separated by the double silicide layer and the barrier metal, and the mutual diffusion between boron, which is an impurity in the P-type diffusion region, and the wiring metal is prevented.

Further, in the semiconductor device of the present invention, since the disadvantage that boron diffuses into the barrier metal to cause a decrease in the concentration of the P-type diffusion region is prevented by the formation of the silicide layer, good ohmic contact is maintained and the P-type diffusion region is maintained. Thus, it is possible to prevent the impurity concentration acting as the diffusion region from lowering.

[0014]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a state where a contact is formed in a manufacturing process of the present invention. The silicon substrate 1 has an impurity diffusion region 2 formed thereon. A BPSG layer 3 which is an insulating layer is formed on the silicon substrate 1 and a contact is formed on the impurity diffusion region 2.
The upper BPSG layer 3 is removed by etching to form a hole having a diameter of about 1 μm.

Then, the first hole is directly formed in the hole by sputtering.
Aluminum silicide (AlSi) layer 4
00Å deposited. Next, titanium is deposited on the AlSi layer 4 by sputtering to a thickness of about 50 to 200 ° to form a titanium layer 5 serving as a second layer. Further, a titanium nitride (TiN) layer 6 acting as a barrier metal is deposited by a reactive sputtering method to a thickness of about 500 to 1000 °. The conditions for forming this third layer are, for example, a pressure of 5
A power of about 4 KW is applied to a circular titanium target having a diameter of 20 cm and a thickness of about 6 mm in an atmosphere having a flow rate ratio of 1 × 10 −3 Torr, argon and nitrogen gas (Ar + N ₂ ), 60
It is formed over about 2 minutes on the silicon substrate 2 which is opposed by a distance of mm.

The barrier metal used in this embodiment is M
It is made of a metal such as o, Ta, Wt, Nb, Cr or a titanium compound such as TiN, TiW. Since the AlSi layer 4 is formed under the titanium layer 5 by the above-described layer formation, the AlSi layer 4 and the titanium layer 5 are formed.
At the interface with titanium silicide (TiSi)
Is formed.

In this embodiment, AlSi is used as the first layer.
Although the layer 4 is used, an Al layer or an Al alloy layer containing at least one metal of at least one of Si, Cu, Pa, and Pt in Al at about 0.3 at% or more may be used.

Thereafter, to form a wiring layer 7 on the titanium nitride layer 6, AlSi is deposited to a thickness of about 1 μm, and
An organic film (resist film) is applied to a thickness of about m, and wiring is formed by parallel plate type RIE (reactive ion etching).

By such a process, the adhesion to the barrier metal (TiN) is improved by sputtering aluminum silicide and titanium. In addition, aluminum silicide is formed between the diffusion region and the barrier metal, and titanium silicide is also formed. Therefore, these act as barriers, so that impurities in the conventional P-type diffusion region diffuse into the barrier metal and cause a decrease in concentration. Can be blocked.

Further, since the silicon substrate and the wiring layer are separated by the barrier metal as in the prior art, Si and Al come into contact with each other, Al diffuses into Si, penetrates the bonding layer, and contacts the silicon substrate and the Al. Leakage due to the connection of the wiring is prevented. Further, it is possible to prevent Si from being deposited on the contact opening and closing the opening, resulting in a high-resistance contact.

[0021]

According to the present invention, by forming a two-layer silicide compound and a barrier metal between the impurity diffusion region and the wiring layer, a good ohmic contact can be maintained, the contact resistance can be reduced, and the P-type can be reduced. This has the effect of preventing a decrease in the impurity concentration acting as a diffusion region.

[Brief description of the drawings]

FIG. 1 is a sectional view of a semiconductor device showing an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 silicon substrate 2 impurity diffusion region 3 BPSG layer 4 AlSi layer 5 titanium layer 6 titanium nitride layer 7 wiring layer

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hideo Takei 1580 Yamamoto, Tateyama-shi, Chiba Pref. N.M.B. Inside the Semiconductor Company (56) References JP-A-3-218011 (JP, A) Surveyed fields (Int.Cl. ⁶ , DB name) H01L 21/28-21/288 H01L 21/3205 H01L 21/3213 H01L 21/44-21/445 H01L 21/768 H01L 29/40-29/51

Claims (1)

(57) [Claims] 1. A silicide compound with Al or an Al alloy, then Ti, a barrier metal is formed on the impurity diffusion region, and a two-layer silicide compound is formed between the impurity diffusion region and the barrier metal. A method for forming a semiconductor device.