JPH0245925A - Manufacture of semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To reduce contact resistance for a fine contact hole and achieve improved density by accumulating an aluminum electrode material containing silicon while heating the open silicon contact hole. CONSTITUTION:A contact hole 4 is formed at an insulation film 3 for a shallow n diffusion layer 2 formed on a silicon substrate 1. An aluminum 5 containing 1-2% silicon is accumulated. A silicon/joule 7 and a silicon/joule 6 are deposited in an extremely small grain diameter on an insulation film 3 within the aluminum 5 and on an contact surface, respectively. Sintering is performed at 400-500 deg.C to form a wiring pattern and reduce contact resistance. Then, in the process for cooling down to normal temperature, silicon epitaxial growth occurs on the contact surface of the semiconductor. However, if a silicon grain 7 exists on the insulation film 3, it becomes a core and becomes a suction source of an excessive amount of silicon. It reduces contact resistance and achieves an improved density.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a high-density, large-scale integrated semiconductor integrated circuit having fine silicon contacts.

Conventional technology When forming an ohmic contact on an N layer or a P layer formed on a silicon substrate, silicon is usually used at 1% to 2%.
Aluminum electrodes containing aluminum are often used. This method is simple and requires only an n+ silicon layer.

Low contact resistance can be obtained for both p+ silicon layers. However, when the contact size is less than 1 micron, silicon in the aluminum precipitates on the contact surface during sintering and covers the entire surface of the contact. In particular, when the silicon surface is in the (100) orientation, significant silicon growth occurs in the lateral direction. Since this silicon is undoped, a high resistance barrier exists between the heavily doped silicon layer and the aluminum electrode, significantly increasing the contact resistance. An example of this is shown in FIG. 11
12 is a silicon substrate, and 12 is an n+ diffusion layer.

13 is an insulating film, 14 is a contact hole, 15 is an aluminum electrode, 16 is a silicon nodule formed on the insulating film, and 17 is silicon grown on the contact surface.

In particular, for fine contacts, if a bias is applied or the substrate is heated to a high temperature during formation of the aluminum electrode in order to improve the step coverage of the aluminum electrode, the contact resistance increases significantly.

Problems to be Solved by the Invention In view of the above-mentioned drawbacks, the present invention is to form an electrode with low contact resistance and excellent step coverage for fine silicon contacts.

Means for Solving the Problems The present invention solves the problems by depositing silicon-containing aluminum electrode material into a silicon contact hole while heating it.

By depositing the active silicon-containing aluminum electrode material while heating, it is possible to prevent silicon from forming on the contact surface during subsequent high-temperature sintering.

Example FIG. 1 shows an embodiment according to the present invention.

1 is a p-type silicon substrate, 2 is a shallow n+ diffusion layer, 3 is an insulating film, 4 is a contact hole, 5 is an aluminum electrode wiring containing silicon, 6 is a silicon substrate grown on the contact surface, 7 is an insulating film These are silicon nodules deposited on top. In this example, a cross section of the contact after sintering at 450° C. is shown, but the amount of silicone that has grown in size 6 is extremely small.

Embodiments of the present invention will be described in detail below in FIGS.
The explanation will be based on C).

In FIG. 2, a shallow n
A contact hole 4 is formed in the insulating film 3 for the diffusion layer 2 . Next, as shown in FIG. 3, aluminum 5 containing 1 to 2% silicon is deposited. At this time, the deposition temperature was set to 100
Set at ℃~300℃. In the aluminum 5, silicon nodules 7 are precipitated on the insulating film 3, and silicon nodules 6 are precipitated on the contact surface with very small particle sizes. At this time, as the deposition temperature is raised, the precipitated silicon grains become thicker.Next, as shown in FIG. 2(C), a wiring pattern is formed and sintering is performed at 400 to 500 DEG C. in order to lower the contact resistance. Silicon growth 6 occurs due to the diffusion of silicon in aluminum 5 onto the contact surface, but 0
．． For a 7 micron contact hole, the silicon in the aluminum 5 only covers 1/10 to 1/3 of the contact surface. The reason for this is thought to be as follows.

When depositing aluminum 5, if the temperature is raised to 100°C to 300°C, a large amount of silicon (dissolves) in the aluminum.
is precipitated and deposited on the insulating film 3 and the surface of the contact 4 in small grain sizes.

After that, sintering is performed at 400°C to 500°C, and in the process of cooling to room temperature, silicon grains grow on the contact surface of the semiconductor, but if silicon grains 7 are present on the insulating film 3, these become nuclei. Serves as a suction source for excess silicon. Therefore, there is less silicon that contributes to shrimp growth (
As a result, shrimp growth during sintering is suppressed.

If the temperature during aluminum deposition is below 100°C, the silicon grains that become the nucleus will not be formed, so there will be a lot of growth on the contact surface after sintering.On the other hand, if the temperature during aluminum deposition is above 300°C, In the process of aluminum deposition, shrimp growth occurs on the contact surface, and further
Shrimp growth is promoted by sintering at ℃.

In the present invention, a method has been described in which the substrate is heated to 100 to 300° C. during aluminum deposition, but the following method may also be used.

That is, after depositing aluminum at room temperature, 10
Annealing is performed at 0 to 300°C. Next, as a second step, sintering is performed at 400-500°C. This method also has the same effect as the method described above.

Figure 4 shows At! vs. substrate temperature during aluminum deposition. -8i
(2%) The dependence of contact resistance on 1n”Si is shown.

The sinter temperature is 450°C for 30 minutes. The contact size is varied from 0.7 to 2 μm as a parameter. For contact sizes below 1.0 microns, 1
The substrate heating deposition method at 00° C. to 300° C. has significantly lower contact resistance than deposition conditions in other temperature ranges.

Therefore, the present invention is highly effective for submicron-sized Ae/Si contacts.

In the above embodiments, contact between Ae and silicon has been described, but the present invention is also effective for materials other than silicon. With materials other than silicon, such as metals and silicides, almost no growth occurs, and silicon nodules are precipitated. According to the present invention, the diameter of the silicon nodule on the contact surface can be reduced based on the principle described above. Therefore, it is possible to prevent an increase in contact resistance. An example of this is shown in FIG. 1 is a semiconductor silicon substrate, 2 is a diffusion layer, 3 is an insulating film, 4 is a contact hole, 8 is a metal made of tungsten, 9 is an aluminum electrode, 10 is a silicon nodule deposited on the contact surface, 11 is deposited on the insulating film 3 silicon nodule.

Effects of the Invention As described above, according to the present invention, it is possible to stably lower the contact resistance of a fine contact hole using a simple method. Therefore, it is possible to realize high-density, large-scale integrated semiconductor integrated circuits with high yield.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an electrode wiring formed in a fine contact according to an embodiment of the present invention, and FIGS. 2(a) to (C) are process sectional views for explaining the manufacturing process of the electrode wiring part. , FIG. 3 is a cross-sectional structure diagram of another embodiment of the present invention, FIG. 4 is a characteristic diagram showing the contact characteristics of the present invention, and FIG. 5 is a diagram showing the electrode wiring formed in a fine contact by the conventional manufacturing method. FIG. 1...Semiconductor silicon substrate, 2...Diffusion layer, 3...Insulating film, 4...Contact hole, 5...Aluminum electrode , 6...
Silicone that has grown on the contact surface, 7...
Silicon nodules deposited on an insulating film. Name of agent: Patent attorney Shigetaka Awano and one other person Figure 1 Figure 1? Fig. πθ Pa in 2θθ Full θ36040θ False M, 5L (2%) No Mk # t, J°C Fig.

Claims (2)

[Claims] (1) A first step of forming a contact hole on a semiconductor layer or an insulating film on metal or silicide, and heating the aluminum thin film containing silicon on the entire surface including the contact hole at a deposition temperature of 100°C to 300°C. a second step of depositing and forming an electrode wiring pattern, and a third step of heat-treating at a temperature higher than the deposition temperature in order to improve the contact characteristics between the semiconductor layer, metal or silicide and the aluminum electrode wiring. A method for manufacturing a semiconductor integrated circuit comprising: (2) A first step of forming a contact hole on a semiconductor layer or an insulating film on metal or silicide, and depositing a silicon-containing aluminum thin film on the entire surface including the contact hole at a temperature of 100°C or less and electrode wiring. a second step of forming a pattern; a third step of heat treatment at a temperature of 100°C to 300°C; A method for manufacturing a semiconductor integrated circuit, comprising a fourth step of performing heat treatment at a temperature higher than the heat treatment temperature of the step.