JPH0697169A - Fabrication of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a method for fabricating semiconductor having a fabrication step for improving coverage of an upper layer winding being formed in contact with a lower layer wiring through a contact hole. CONSTITUTION:An alloy layer 8 of aluminium 6 and high melting point metal 7 is formed on a surface having a recess exposing an aluminium wiring layer on the bottom face thereof while copying the profile of the recess and then an aluminium containing layer is formed on the alloy layer 8 while filling the recess through sputtering at a temperature of 300-600 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device having a manufacturing process for improving the coverage ratio of an upper layer wiring formed in contact with a lower layer wiring through a contact hole. Regarding

[0002]

2. Description of the Related Art As shown in FIG. 4, an insulating film 4 is formed on a lower aluminum wiring 3 formed on a silicon substrate 1 with an insulating film 2 interposed therebetween, and a contact hole 5 is formed in the insulating film 4. A titanium film 7 is formed on the insulating film 4 including the inner surface 5 by a sputtering method. Then 30
Aluminum is sputtered at a temperature of 0 to 600 ° C. to fill the contact hole 5 to form an aluminum-containing layer on the titanium film 7, and this is patterned to form the upper wiring 9.

[0003]

Aluminum-containing layer 9
As shown in FIG. 5, the problem that the cavities 10 are generated inside the contact hole 5 when forming the Al is solved by sputtering aluminum at a high temperature of 300 to 600 ° C. It was However, in the upper wiring 9 on the contact hole 5,
As shown in FIG. 4, the problem that the dent occurs and the coverage rate decreases and the disconnection occurs in the thin film portion has not been solved. Here, the coverage rate is an expression when the thickness formed on the flat portion is A and the minimum thickness of the concave portion is B in FIG.

[0004]

## EQU1 ## Coverage rate (%) = (B / A) × 100

An object of the present invention is to eliminate this drawback, and to provide a method of manufacturing a semiconductor device having a manufacturing process for improving the coverage ratio of an upper wiring formed in contact with a lower wiring through a contact hole. To provide.

[0006]

The above-mentioned object is to form an alloy layer of aluminum and a refractory metal on a surface of an aluminum wiring layer having a recess exposed at the bottom so as to reflect the shape of the recess, This is achieved by a method for manufacturing a semiconductor device, which has a step of filling the above-mentioned recesses on this alloy layer and forming an aluminum-containing layer by sputtering at a temperature of 300 to 600 ° C. In addition, the formation of the alloy layer of aluminum and the refractory metal is performed by forming the aluminum-containing film in 100 to 2
A high melting point metal film is deposited on the aluminum-containing film at a temperature of 300 to 500 ° C. for 100 to 20
It may be deposited to a thickness of 00Å or sputtered using a target containing aluminum and a refractory metal.

[0007]

As shown in FIG. 1, the lower wiring 3 is formed on the silicon substrate 1 with the insulating film 2 interposed therebetween, and the insulating film 4 is formed on the lower wiring 3.
An alloy layer 8 of aluminum and a refractory metal is formed on the surface where the contact hole 5 is formed, the contact hole 5 is filled, and an aluminum-containing layer 9 is deposited on the alloy layer 8 at a temperature of 300 to 600 ° C. Then, the inventor of the present invention has found that the coverage rate of the aluminum-containing layer 9 is significantly improved. It is considered that this is because the alloy layer of aluminum and the refractory metal has a higher surface mobility of aluminum than the film of the refractory metal alone such as titanium.

By the way, when aluminum and refractory metal are alloyed, volume contraction occurs. Therefore,
When a refractory metal film is formed first and then an aluminum film is formed on it and alloyed, aluminum is softer than refractory metal, so the refractory metal film floats up and a gap is formed between it and the underlying wiring. As a result, there arises a problem that the contact resistance increases. Therefore, like the present invention, it is important to first form an aluminum film and then form a refractory metal film on the aluminum film for alloying. Incidentally, 300 to 500
It was confirmed by experiments that if a refractory metal film is deposited at a temperature of ° C, it reacts with the previously deposited aluminum film to form an alloy layer of aluminum and refractory metal.

Further, instead of a method of forming an alloy layer of aluminum and a refractory metal by sputtering using a target having aluminum and a refractory metal, an alloy of aluminum and a refractory metal is used as a target. There is a method of using and sputtering, but in this case there is a problem that particles in the deposited alloy layer increase, so
Even if this problem is solved, it can be implemented.

Further, the lower limit temperature of 300 ° C. when depositing the upper aluminum-containing layer is determined by the condition that no nest is generated in the recess due to the shadowing action, and the upper limit temperature of 600 ° C. is the condition below the melting point of aluminum. It was decided.

The formation of an alloy layer of aluminum and a refractory metal on the lower surface of the aluminum wiring layer also has the effect of improving migration resistance.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of forming a multi-layer wiring according to an embodiment of the present invention will be described below with reference to the drawings.

Referring to FIG. 1 (a), a silicon dioxide film 2 is formed on a silicon substrate 1, and aluminum is sputtered on the silicon dioxide film 2 at a temperature of 200 ° C. to form an aluminum-containing layer having a thickness of 7000Å. Is patterned to form the lower layer wiring 3.

Referring to FIG. 1B, the PSG film 4 is formed to a thickness of 1 μm by the CVD method, and the PSG film 4 is patterned to form a contact hole 5 of 1 μm □. Next, aluminum is sputtered at a temperature of 200 ° C. to form an aluminum film 6 having a thickness of 500 to 1000 Å, and then titanium is sputtered at a temperature of 300 to 500 ° C. to form a titanium film 7 having a thickness of 500 to 1000 Å. . During this sputtering step, the aluminum film 6 previously formed reacts with titanium to form the aluminum-titanium alloy layer 8.

Referring to FIG. 1C, aluminum is sputtered on the aluminum / titanium alloy layer 8 at a temperature of 300 to 600 ° C. to fill the contact hole 5 to form an aluminum containing layer having a thickness of 7,000 to 10,000 Å and patterned. Then, the upper wiring 9 is formed. Almost no dent was formed on the contact hole 5, and a flat upper wiring was formed.

In the examples, the case where titanium is used as the refractory metal has been described, but the same effect can be obtained when other refractory metals are used. Further, the aluminum film 6 deposited when forming the aluminum / titanium alloy layer does not necessarily need to be pure aluminum, and may contain copper / silicon or the like. Specifically, an aluminum film containing 1% of silicon or an alloy film of aluminum and copper may be used. The method for depositing the aluminum film 6 and the titanium film 7 is not limited to the sputtering method, and the CVD method may be used.

Referring to FIG. 2, in order to investigate the relationship between the deposition temperature of the titanium film 7 deposited on the aluminum film 6 and the formation state of the aluminum-titanium alloy, aluminum 3 titanium (Al ₃
The strength of the Ti) alloy (KCPS (kilo counts / second)) was measured. The result is shown in FIG.

If the deposition temperature of titanium is set to 300 ° C. or higher, an Al ₃ Ti alloy is formed, and when the deposition temperature rises, A
It was confirmed that the amount of l ₃ Ti alloy produced increased.

FIG. 3 shows the relationship between the deposition temperature of titanium and the coverage ratio of the upper wiring formed by filling the contact hole. When the titanium deposition temperature is 300 ° C. or lower, the coverage ratio is low because the aluminum-titanium alloy layer is not formed as described in FIG. Titanium deposition temperature is 300 ℃
As shown in FIG. 2, it was confirmed that the production rate of the aluminum-titanium alloy layer increased with the increase of the value over the range, and the coverage rate was significantly improved accordingly.

[0020]

As described above, in the method of manufacturing a semiconductor device according to the present invention, an alloy layer of aluminum and a refractory metal is formed on the surface having a recess, and the alloy layer of 300 to 500 ° C. is formed on the alloy layer. By depositing the aluminum-containing layer at a high temperature, the surface mobility of aluminum is improved, the coverage ratio is improved, and the aluminum-containing layer having a flat surface is formed, which contributes to the improvement of the integration degree of LSI. However, it is big.

[Brief description of drawings]

FIG. 1 is a process drawing of forming a multilayer wiring.

FIG. 2 is a graph showing the relationship between the X-ray diffraction intensity of Al ₃ Ti produced when an aluminum film and a titanium film are successively deposited and the titanium deposition temperature.

FIG. 3 is a graph showing a relationship between a coverage ratio and a titanium deposition temperature when an aluminum / titanium alloy layer is formed by successively depositing an aluminum film and a titanium film, and an aluminum-containing layer is formed thereon. .

FIG. 4 is a process drawing of a conventional multilayer wiring.

FIG. 5 is an explanatory diagram of a nest generated in a contact hole.

[Explanation of symbols]

 1 Silicon substrate 2 Insulating film 3 Lower layer wiring 4 Insulating film 5 Contact hole 6 Aluminum film 7 Titanium film 8 Aluminum / titanium alloy layer 9 Upper layer wiring 10 Nest

Claims (3)

[Claims] 1. An aluminum wiring layer is formed with an alloy layer of aluminum and a refractory metal on a surface having a recess exposed at the bottom so as to reflect the shape of the recess, and the recess is filled on the alloy layer. Aluminum containing layer 3
A method of manufacturing a semiconductor device, comprising a step of forming by sputtering at a temperature of 00 to 600 ° C. 2. An aluminum-containing film having a thickness of 100-2000.
A high melting point metal film is deposited on the aluminum-containing film at a temperature of 300 to 500 ° C. to a thickness of 100 to 2000 Å to form an alloy layer of aluminum and a high melting point metal. The method of manufacturing a semiconductor device according to claim 1, wherein the semiconductor device is manufactured. 3. The manufacturing of a semiconductor device according to claim 1, wherein sputtering is performed using a target containing an aluminum-containing material and a refractory metal to form an alloy layer of aluminum and the refractory metal. Method.