JPS6038344B2 - Method for manufacturing phosphosilicate glass film by low pressure vapor phase growth method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for growing high quality polysilicate glass (PSG) films, particularly on wafer surfaces, by low pressure vapor deposition.

Low-pressure vapor phase epitaxy is one of the wafer processing methods used when manufacturing semiconductor devices such as ICs and LSIs, and the pressure inside the reaction vessel is reduced to around the Iton while a reaction gas is passed through the vessel. In this method, a film is grown on the surface of wafers arranged vertically.

The advantage of this growth method is that not only can a large number of wafers be processed at once, but also a film can be grown that is uniformly distributed on the wafer surface. By forming a PSG film on the surface of a wafer where devices are provided, it acts as an IC protective film that prevents external intrusion, moisture, etc. from affecting the operation of the device, while also preventing multilayer wiring. When a PSG film is used, disconnection is less likely to occur, so it is widely used as an interlayer insulating film.

When growing a PSG film using the low-pressure vapor phase growth method, the film is grown by reacting a mixed gas of high concentration silane (SiH4) and phosphine (PH3), but the reaction vessel is not sufficiently filled with 02 gas. As a result, the PSG film is not sufficiently oxidized, and a PSG film rich in silicon (Si) is formed.

Conventionally, the following methods have been devised to solve the above problem. Without flowing the SiH4 and PH3 mixed gas and 02 gas at the same time, the 02 gas is
A method of keeping two gases flowing was considered.

However, in this method, when only the 02 gas is flowing into the reaction vessel, no gas is flowing through the mixed gas introduction pipe, so the pressure in the pipe is lower than in the vessel.
Therefore, when 02 gas enters the pipe and the mixed gas is allowed to flow, a reaction occurs within the pipe, forming a white powdery oxide that is introduced into the reaction vessel together with the mixed gas and reaches the surface of the wafer. It adheres to the PSG film, causing cloudiness and cloudiness on the PSG film. In order to grow a dense and uniform film,
It is preferable to grow the PSG film by reacting the reaction gas on the wafer surface, and the PSG film obtained by the reaction on the wafer surface does not become cloudy. Therefore, a cloudy or cloudy PSG film is formed as a rough and non-uniform film, and cannot serve as a protective film or the like. In addition, high concentration Si
With Ratio and 02, the reaction occurs rapidly, so if the reaction gas is introduced from one place, it is difficult to grow the same film on all the wafers in the reaction vessel, so split introduction is used to introduce the same reaction gas from several places. is used. The purpose of the present invention is to prevent cloudiness, cloudiness, and Sj-rich films from occurring in PSG films grown using low-pressure vapor phase growth, and to produce high-quality PSG films.
To provide SG films.

Hereinafter, the present invention will be explained with reference to the drawings.

In order to explain the present invention, FIG. 1a is a top sectional view of a reaction vessel showing an example of the configuration of a low-pressure vapor phase growth apparatus, FIG. 1b is a cross-sectional view taken along the line X-Y in FIG. 1a, and FIG. A diagram showing the introduction timing of each reaction gas over time starting from the start of the reaction in an embodiment of the present invention. Figure 3 shows high concentration SiA and PH3 mixed in the high concentration SiA and PH3 mixed introduction pipe over time. ratio and P
It is a figure showing the expected concentration distribution of H3 mixed gas and N2 gas.

First, the configuration of the low-pressure vapor phase growth apparatus will be explained using FIGS. 1a and 1b. The reaction vessel 1 consists of a tube with a circular cross section,
A resistance heating furnace 2 is arranged around the outer periphery of the container 1 so that all the wafers are uniformly heated, and the temperature is maintained at 450° C. or lower to prevent the aluminum wiring from melting at high temperatures. Further, a large number of disk-shaped wafers 3 are placed inside the holder 4 on a holder 4. A vacuum pump 5 such as a rotary pump is installed at one end of the reaction vessel 1, and the interior of the vessel 1 is
Maintain low pressure between ITorr. 02 gas 6 is made to flow into the container 1 as a carrier gas. Reactant gas introduction pipes 7 and 8 having a large number of spouts are drawn in the direction of the reaction vessel wall in the reaction vessel 1, and pipe 7 carries 02 gas, and pipe 8 carries high-concentration Si ratio and PH3 mixed gas in the directions of the arrows. However, at the start of the reaction, 02 gas 9 is introduced into pipe 7, and at the same time nitrogen (N2) is introduced into pipe 8.
) Gas 10 is replaced, and high-concentration Si and PH3 mixed gas 11 is sequentially introduced into the same pipe 8 along with N2 gas 10 (FIG. 2). As time passes when each of the reaction gases is circulated in this way, it is naturally expected that the respective concentration distributions of the N2 gas 10 and the mixed gas 11 in the pipe 8 will become as shown in Fig. 3. Will. According to the present invention, since the 02 gas is introduced into the pipe 7 at the same time as the N2 gas is introduced into the pipe at the start of the reaction, the 02 gas cannot enter into the pipe 8.
Therefore, cloudiness or cloudiness does not occur in the PSG film.

In addition, since the high concentration Si ratio and the PH3 mixed gas are diluted with N2 gas and the concentration gradually increases, the mixed gas can be sufficiently oxidized and a high quality PSG film can be grown, resulting in a high quality PSG film. It has the effect of being able to obtain
In the embodiment of the present invention, the high-concentration Si ratio and PH3 mixed gas was introduced immediately after the introduction of the N2 gas, but the mixed gas may be introduced during the introduction of the N2 gas. Further, although N2 gas was used here, an inert gas may be used instead of N2 gas.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an example of the configuration of a low-pressure vapor phase growth apparatus for explaining the present invention, Fig. 2 is a diagram showing the introduction timing of each reaction gas, and Fig. 3 is a diagram showing the introduction timing of each reaction gas. N2
It is a diagram showing the concentration distribution of gas, high concentration Si ratio, and PH3 mixed gas over time. 1... Reaction vessel, 2... Furnace, 3...
・Wafer, 5...Vacuum pump, 7...02 gas introduction pipe, 8...High concentration Si ratio and PH3 mixed gas introduction pipe, 9...02 gas, 10...・…N2
Gas, 1 1... High concentration Si ratio and PH3 mixed gas. Old lady 3 drawings 1 drawing

Claims (1)

[Claims] 1. Bring the inside of the reaction container into a reduced pressure state, and separately introduce a mixed gas of silane and phosphine and oxygen gas into the container,
In the method of growing a phosphosilicate glass film on the surface of a wafer placed in the container and heated, a mixed gas of silane and phosphine is introduced after the introduction of oxygen gas is started, and before the introduction of the mixed gas is started, the mixed gas is introduced. A method for producing a phosphosilicate glass film by a low-pressure vapor phase growth method, which is characterized by introducing nitrogen or an inert gas into a pipe.