JPS62296473A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To remove an interference with etching of a contact hole and the like in a subsequent process, by laying a polycrystalline silicon film beforehand under a boron phosphorus glass layer. CONSTITUTION:A silicon oxide film 6 is formed in such a degree that a resistance value of a source-drain element is not increased and that a polycrystalline silicon gate edge is not raised. Next, polycrystalline silicon 7 is made to grow, by a reduced-pressure chemical vapor deposition method or the like, to have a thickness a little smaller than a half of the thickness of the oxide film whereby the polycrystalline silicon is oxidized, during a time required for implementing a flow processing of a boron phosphorus glass layer by water vapor. Thereafter the boron phosphorus glass layer 8 is formed by deposition. When heat treatment is applied in an atmosphere of water vapor and at a high temperature of 800 deg.C or above, subsequently, the boron phosphorus glass layer 8 of the surface shows fluidity, the polycrystalline silicon turns entirely to be an oxide film, and simultaneously the surface becomes smooth.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Industrial Application Field The present invention relates to a method for manufacturing a semiconductor device, and particularly to a process for manufacturing a metal-oxide semiconductor integrated circuit (hereinafter abbreviated as MO3LSI). It is.

Prior Art A conventional example will be explained with reference to FIG. For example, p-type (100
) A field oxide film 2 is formed on a silicon substrate 1 of 10 to 15 Ω by using a selective oxidation method or the like. Next, a gate oxide film 3, which determines the characteristics of the transistor, and an impurity-doped polycrystalline silicon electrode 4 are grown using an electric furnace and low pressure chemical vapor deposition, and a desired gate electrode pattern 4 is formed using photolithography. do. For example, arsenic is applied to this polycrystalline silicon using the self-seven line method at an accelerating voltage of 80 Ke.
By performing ion implantation of about 5 to ex 1015/ail at about V and activating it, the source 5 or
Form rain 5. Next, if silicon oxide film 6 and phosphorus and boron are each added individually by chemical vapor deposition method, approximately 7~
A silicon oxide film 8 (hereinafter abbreviated as a boron/phosphorus glass layer) containing about 10% of the silicon oxide film 8 (hereinafter abbreviated as boron/phosphorus glass layer) is grown.

The reason why the silicon oxide film 6 is grown in this process is to prevent boron or phosphorus from being introduced as an impurity into the underlying source or drain 5 from the upper boron phosphorus glass layer 8. This explanatory diagram shows the case of an N-channel MOS transistor, so phosphorus may be included, but it is absolutely necessary, for example, in a CMOS process where a P-channel transistor coexists. After forming an interlayer insulating film such as layer 8 in this manner, heat treatment is performed at 1000° C. for about 20 minutes in a steam atmosphere. Then, as shown in Fig. 2 (fC), the top layer of boron phosphorus glass 8 exhibits fluidity even though it is solid, and changes from the almost vertical coating shape shown in Fig. 2 (b) to a considerable slope. An interlayer insulating film consisting of layers 8 having an angle is formed.

Therefore, for example, it is predicted that the stepped portion on the polycrystalline silicon 4 will become extremely smooth, and that the metal wiring layer (not shown) formed on the interlayer insulating film 8 will also become smooth, reflecting the shape of the underlying layer. .

This is called phosphorous glass flow, and it is very widely used to reduce sudden steps. Smoothness is best in a water vapor atmosphere, and glass fluidity does not easily occur in a simple nitrogen atmosphere.

Currently, phosphorus glass is often processed in an atmosphere containing phosphorus at high temperatures of over 1000°C, and in order to take advantage of its fluidity even at much lower temperatures, a layer of boron-phosphorus glass that also contains boron is used as mentioned above. is being considered.

Problems to be Solved by the Invention As mentioned above, it was stated that a steam atmosphere is preferable as the atmosphere for imparting fluidity to the phosphorus glass layer or the boron phosphorus glass layer, but during heat treatment, the atmosphere shown in FIG. 2 (C) As shown in FIG. 2, oxidized species reach the underlying substrate through the interlayer insulating films 6 and 8, resulting in two problems such as an increase in source-drain resistance due to the formation of a raised part 4A at the edge of the gate polycrystalline silicon and an oxidized part 5A in the source-drain part. A problem has arisen. These problems were not a particularly big problem while the device size was large, but as the device size becomes smaller, the difficulty in controllability and the deterioration of characteristics are becoming more noticeable.

The interlayer insulating film is usually very thick, 6,000 to 1 μm, but the temperature during deposition is as low as about 400° C., and it does not seem to have any stopping effect on water vapor oxidation species. Furthermore, it is well known that the source/drain layer is a highly concentrated impurity layer, and the oxidation rate is much faster than in the case of no impurities. It is understood that the above-mentioned problems arise because the growth rate is fast.

Means for Solving the Problems The method of the present invention, when manufacturing a MOS integrated circuit having a gate electrode, a source, and a drain structure, involves forming the gate electrode, source, and drain on one main surface of a semiconductor substrate, and then performing the steps described above. A step of forming an interlayer insulating film with a metal wiring layer connected to the gate electrode, source and drain, and forming a silicon oxide film by chemical vapor deposition, and a step of depositing a polycrystalline silicon film on this film. , a step of depositing a silicon oxide film containing boron and phosphorus individually or simultaneously, and a step of heat-treating the semiconductor substrate at a temperature above soo'c in a water vapor atmosphere, and converting the polycrystalline silicon film into an oxide film entirely. It is.

Function By placing a polycrystalline silicon film under the boron phosphorus glass layer, the oxidizing species are first spent oxidizing this polycrystalline silicon layer before reaching the underlying layer, and as a result, the oxidation species are formed. Since the film is a silicon oxide film, all interlayer insulation films are
Since the film is of the same type, it will not cause any problems in the next process such as etching of contact holes.

Example An embodiment of the present invention will be described with reference to FIG.

The method may be the same as the conventional method until the source/drain of the MOS transistor is formed. Next, in order to prevent impurity contamination from the boron phosphorus glass layer, chemical vapor deposition or low-intensity dry oxidation is used to oxidize the polycrystalline silicon to an extent that increases the resistance value of the source/drain region and does not lift the polycrystalline silicon gate edge. A silicon film 6 is formed. The polycrystalline silicon 7 is then heated in a vacuum chemical vaporizer to a thickness slightly less than half the oxide thickness that the polycrystalline silicon will be oxidized during the time required to carry out the water vapor flow treatment of the boron phosphorous glass layer described below. Grow by phase deposition method etc. For example, 900℃.

If a steam flow treatment is performed for 60 minutes, a film thickness of about 700 deer is desirable. After that, add 500% of boron phosphorus glass layer 8.
It is deposited with a film thickness of about 0 to 9000.

This is shown in FIG. 2(b). Next, in a steam atmosphere, 8
Heat treatment is carried out at a high temperature of 00° C. or higher, for example, 80° C. to 100° C., for 15 to 30 minutes at a high temperature and 60 to 180 minutes at a low temperature. Then, the boron phosphorus glass layer 8 on the surface exhibits fluidity, and the entire polycrystalline silicon 7 becomes an oxide film, and at the same time, the surface becomes smooth as shown in FIG. 1(C).

Effects of the Invention According to the method of the present invention, the surface becomes smooth, the underlying source/drain regions are not oxidized, and the edges of the polycrystalline silicon edges are not lifted. As a later step, a contact hole is formed in the interlayer insulating film,
Metal wiring is formed to connect to the underlying layer, but it has the advantage that there is no disconnection at the stepped portion or etching residue at the stepped portion due to anisotropic etching.

[Brief explanation of drawings]

FIG. 1 is a process sectional view showing a method for manufacturing a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a process sectional view showing a conventional manufacturing method. 6...Silicon oxide film, 7...Polycrystalline silicon, 8...Boron phosphorus glass layer. Name of agent: Patent attorney Toshio Nakao and 1 other person 4.
-96 Crystal Sisocon 1-Fu Figure 2

Claims (1)

[Claims] When manufacturing a MOS integrated circuit having a gate electrode, a source, and a drain structure, after each of the gate electrode, source, and drain is formed on one main surface of a semiconductor substrate, the gate electrode,
A step of forming an interlayer insulating film with a metal wiring layer connected to the source and drain, a step of forming a silicon oxide film by chemical vapor deposition, a step of depositing a polycrystalline silicon film, and a step of depositing boron and phosphorus separately or A method for manufacturing a semiconductor device, comprising simultaneously depositing a silicon oxide film and heat-treating the semiconductor substrate at a temperature of 800° C. or higher in a steam atmosphere, thereby converting all of the polycrystalline silicon film into an oxide film. .