JPS612317A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To contrive reduction of thermal stress of an insulating film and suppression of H2 reducing action as well as to prevent exfoliation by a method wherein, when a semiconductor substrate having the insulating film such as an SiO2 film and the like is heat-treated in an H2 atmosphere, the heat treatment is performed at the temperature of 1,050 deg.C or more. CONSTITUTION:An SiO2 film 12 is formed by oxidizing a P type silicon substrate 11, and a patterning is performed on the film 12 using a photoresist as a mask. Then, the resist is removed, and a P type single crystal silicon layer 13 is epitaxially grown on the exposed part only of the substrate 11 in a selective manner. When said epitaxial growing method is performed, N2 gas is introduced into a furnace, the atmosphere in the furnace is then changed to H2, and after an H2 purge is performed, the furnace is heated up to the prescribed temperature maintaining the H2 atmosphere. The above-mentioned temperature is to be set at 1,050 deg.C or less. After several minutes have passed from the point of time when the furnace reached the prescribed temperature, reaction gas is introduced into the furnace. As a result, epitaxial growth is started. The substrate 11 is then polished.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an improvement in a method for manufacturing a semiconductor device, which includes a step of heat-treating a semiconductor substrate having an insulating film of 5 in 2 or the like on its main surface in a hydrogen atmosphere.

[Background technology]

In semiconductor devices in which circuit elements are formed on a semiconductor substrate, typically silicon, there are some steps in the manufacturing process.
There is a step of heat-treating the silicon substrate in a hydrogen (H2) gas atmosphere. For example, 8102 on the main surface of a silicon substrate.
One such method is the so-called selective silicon epitaxial growth method, in which single-crystal silicon is selectively grown in vapor phase only on the exposed surface of the substrate after patterning an insulating film such as H
By the way, the silicon substrate is heat-treated to about 1100°C in an atmosphere of not only 2 gases but also other reactive gases.
One of the applications of such selective epitaxial method is
I E DM (International Elec
tron Devices Meeting ) T
LS on page 241 of mechanicalDigest
An example will be shown in which this method is used for isolation technology between elements. That is, the first
As shown in the figure, a 5in2 film 2 formed with a thickness of 1 to 2 μm on the main surface of a silicon substrate 1 is pattern-etched, and
S as a reactive gas is applied to the exposed main surface of the silicon substrate 1.
i By heat-treating this using H2C4HC13Ht system, a single crystal silicon layer 3 is epitaxially grown, whereby the 5102 film 2 is used as an element isolation region, the single crystal silicon layer 3 is used as an element region, and a bird's beak is formed. This is intended to suppress the occurrence of , and to achieve higher integration of the element.

However, when the present inventor investigated such a selective eviction technique, it was found that peeling of the Sin film 2 occurs in the initial stage of processing, which adversely affects the reliability of the semiconductor device. As shown in the figure, this peeling progresses from the edge of the 5102 film 2 to form voids 4, and according to experiments, it occurs simply by heating in an I-12 atmosphere. There is. That is, in the epitaxial growth method described above, 5iH2C
Before flowing 112° HCl gas into the furnace, that is, before the epitaxial growth begins, there is a step of flowing only H2 gas into the furnace. This is done because it is necessary to completely replace the atmosphere in the furnace with H2, and to lightly gas-etch the silicon surface with H2 to expose a clean silicon surface. The SiO2 film 2 peels off. Based on these facts, the present inventor conjectures that this peeling is caused by the reduction action of 5in2 by H2 and the addition of effects such as stress and a difference in coefficient of thermal expansion.

Therefore, in the above literature, as shown in Fig. 2, Sin2
A silicon nitride (SisN4) film 5 is formed on the side wall of M2.
proposed a method to protect 5IO2 from H2 attacks. However, even with this measure, it is difficult to reliably prevent peeling.

[Objective of the Invention 1 The object of the present invention is to provide a semiconductor substrate having an insulating film such as 5102 film on its main surface, which will not peel off even when heat-treated in an H2 atmosphere, and therefore have high reliability. An object of the present invention is to provide a manufacturing method that can easily manufacture a semiconductor device.

The above and other objects and novel features of the present invention include:
It will become clear from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief summary of the typical inventions disclosed in this application is as follows Q). In other words, when a semiconductor substrate having an insulating film such as a SiO2 film on its main surface is heat-treated in an H2 atmosphere, , that temperature]
By regulating the temperature to 050°C or less, we aim to reduce the thermal stress in the insulating film in particular and suppress the H7 reduction action to prevent peeling in the insulating film, and thereby manufacture highly reliable semiconductor devices. It is something that can be done.

This will be explained in detail as follows.

The present inventor has tried various applications of S on silicon substrates.
When examining the peeling of the iO□ film, it was found that peeling has a strong correlation with the heat treatment temperature in an H2 atmosphere. That is, a silicon substrate having a buttered 5I02 film was heat-treated at various temperatures in an H2 atmosphere, and
When we calculated the relationship between the amount of peeling l and the temperature T'O, we found that
A correlation diagram of the figure was obtained. From this, it can be seen that peeling of the 5in2 film occurs above 10,700°C, and the higher the temperature, the greater the degree of peeling.
It can be seen that peeling can be prevented by setting the temperature to 1050°C or less, taking into account temperature variations. Therefore, H
It can be seen that in a process in which heat treatment is performed in two atmospheres, if the heat treatment temperature is set to 1050° C. or lower, peeling of the 5L02 film on a silicon substrate can be prevented and reliability can be improved.

〔Example〕

FIG. 4 shows an example in which the present invention is applied to an N-channel MO8LSI, in particular to an isolation technique between elements.

First, as shown in FIG. 4(A), a P-type silicon substrate 11 is thermally oxidized to form a 5102 film 12, and this is patterned as shown in FIG. 3) using a photoresist (not shown) as a mask. This remaining 5102 film 12a is configured as an element isolation region.

Next, after removing the photoresist, selective K is applied only to the exposed part of the silicon substrate 11 as shown in the same figure (cl).
P-type single crystal silicon N13 is epitaxially grown to be sufficiently thick so as to overhang the 5102 film 12a. During this epitaxial growth, S
r H2C13, -HCiJ -N2 system is used as the reaction gas, and the process at this time is carried out as shown in Figure 5. First, N2 gas is introduced into the furnace to create an N2 atmosphere inside the furnace and N2 purge) , then switch the atmosphere to N2
After performing two purges, raise the temperature inside the furnace to a predetermined temperature while maintaining the N2 atmosphere. This temperature is set to 050°C or less for the reasons mentioned above. After several minutes have elapsed since the temperature in the furnace reached a predetermined temperature, 5iH2C, HC7 gases were passed into the furnace. This starts epitaxial growth. After performing epitaxial growth for a predetermined period of time, S 1H2C12,HC,/! The supply of gas is stopped, the inside of the furnace is replaced with N2, and after a few minutes, the temperature inside the furnace begins to drop to room temperature, and the process is completed.

Next, the surface of the silicon substrate 110 is polished by a method commonly used for polishing wafers, as shown in G) 1 of the same figure, and S10. The portion of the single crystal silicon layer 13 exposed above the film 12a is polished until its upper surface coincides with the upper surface of the 5in2 film 12a. As a result, a highly flat wafer consisting of the element region 13a and the inter-element isolation region 12a can be formed. An N-channel MOS transistor consisting of a gate insulating film 14, a gate electrode 15, and source/drain regions 16a and 16b is formed in the thus obtained device region (single crystal silicon layer) 3a according to a normal process as shown in FIG. Form.

Here, as shown in Figure 7, the element isolation region and the S
iO,, S i 3N is applied to the soil of the film 12a by CVD method etc.
The fourth film 17 may be formed as a wear-resistant film.

By forming this Si, N+l film 17, the polishing rate ratio between the single crystal silicon layer 13 and the Si, N4 film 17 is 50 when polishing the single crystal silicon layer 13 shown in the same figure).
:L, it is possible to achieve a flat surface with high accuracy. Note that the polishing rate ratio between the single crystal silicon layer 13 and the 5in2 film 12a is 15:1.

After polishing, as shown in the figure (C), the surface of the single crystal 7927 layer 13a serving as the element region is oxidized to form a protective 5i02 film 18, and the Si3N4 film 17 is etched away using soil. )), and then by removing the 5i02 film 18, a flat surface 7. C wafers can be obtained.

According to the embodiments described above, the epitaxial growth is performed at a temperature of 1050° C. or less in an H gas atmosphere, and in this example, the epitaxial growth is performed at a temperature of 1050° C., so that the S s O provided on the surface of the silicon substrate 11 is formed into a film. The reduction action and thermal stress caused by 12aK are reduced, thereby preventing the 5i02 film 12a from peeling off, thereby increasing the reliability of the element isolation region or the entire semiconductor device.

〔effect〕

(1) When heat-treating a silicon substrate with a surface KSiO2 film in an N2 gas atmosphere, such as during epitaxial growth, the temperature is set to 1050°C or lower [7], so that the reduction effect and thermal stress in the Si film can be reduced. This has the effect of preventing the 5I02 film from peeling off.

(2) When the single-crystal silicon layer as the element region is epitaxially grown on the silicon substrate provided with the 8102 film as the element isolation region, the temperature is set at 1050°C or less, so it is reliable as the element isolation region. It is possible to obtain a highly reliable semiconductor device because it has improved properties and is not damaged even during subsequent polishing.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor. For example, the same heat treatment can be applied to semiconductor devices other than non-conductive semiconductor devices, and also when the semiconductor device has an insulating film other than a 5in2 film.

[Application field]

In the above explanation, the invention made by the present inventor is mainly applied to the ICJ epitaxial growth technology of single crystal silicon, which is the field of application for which the invention is based, but the invention is not limited to this, and the invention is not limited to this. As long as the process involves heat treatment, it can be similarly applied to other treatments such as heating and scratching.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view explaining the conventional problem, Fig. 2 is a cross-sectional view showing an example of the conventional countermeasure, Fig. 3 is a characteristic diagram explaining the present invention in detail, and Fig. 4 w~) are the present invention. Figure 5 is a temperature control graph, Figure 6 is a cross-sectional view of an N-channel MO8) transistor, Figure 7 is a process cross-sectional diagram of an example process in which 11=-semiconductor substrate, ] 2. 12 a-8i02 film (insulating film), 13. 13a... single crystal silicon layer (device region), ] 4... gate insulating film, 15... gate Electrodes, 1.6a, 16b... drain region, ]
7...Si3N4 film (wear-resistant film), J8...5i0
21i! 0 2nd Illustration ('C) Figure 4 (A) Figure 5 °5

Claims (1)

[Claims] 1. A method for manufacturing a semiconductor device including a step of heat-treating a semiconductor substrate having an insulating film pattern on its main surface in a high-temperature hydrogen atmosphere, wherein the heat treatment temperature is set to 1050° C. or less. A method for manufacturing a semiconductor device, characterized by: 2. A silicon dioxide film is selectively formed on the main surface of a silicon substrate, and single crystal silicon is epitaxially grown on the main surface of the silicon substrate other than this silicon dioxide film, and the temperature during this epitaxial growth is 1050°C or less. A method for manufacturing a semiconductor device according to claim 1.