JPS5955034A - Formation of interelement isolating film - Google Patents

Abstract

PURPOSE:To enable to form the interelement isolating SiO2 film with a small area by a method wherein after a resist film and the protruding oxide films of silicon epitaxial layers formed on a silicon substrate are etched, while silicon dioxide films remaining on the epitaxial layers are removed. CONSTITUTION:The photo resist film 15 is applyingly formed on the substrate, and the upper part of the surface of the substrate is made to be the flat condition by burying the gaps between the Si layers 13 grown in the convex type on the SiO2 films 12. After then the substrate is installed in a reaction tube, mixed gas of carbon tetrafluoride gas and O2 gas is introduced in the reaction tube, a high-frequency voltage is applied between an electrode and a substrate installation base in the reaction tube, and the photo resist film 15 on the surface of the substrate and the SiO2 films 14 protruding locally on the interelement isolating SiO2 films 12 are etched at the same time by plasma to be removed. The SiO2 films 14 remaining on the epitaxial layers 13 are etched to be removed by the mixed liquid of hydrofluoric acid and ammonium fluoride, and the surface of the Si substrate demarcated by the interelement isolating SiO2 films 12 having the flat surface and the small area is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention is a book related to an improvement in a method for forming an isolation film between elements used in manufacturing semiconductor devices such as ICs and LSIs. □(c) Technology background 01 When forming semiconductor devices such as LSI, silicon (
A semiconductor device is formed by forming a silicon oxide (S1O2) film in a predetermined pattern on a semiconductor substrate such as 5102 film, and forming semiconductor elements such as transistors within the area defined by the 5102 film. .

It is desirable to form such a S'x0.1 film for isolation between elements with a surface area as small as possible, and to form as many semiconductor elements as possible on one 81 substrate at high density. .゛(Q) Conventional technology and problems □ ・Conventionally, as a method for forming such a Si film for isolation between elements, as shown in Fig. A patterned photoresist film 2 is formed, and the photoresist film 2 is etched using an etching solution of FCOll (FCOll) using a mask. The inclined surface 4 of the groove 8 is (Il
l) Anisotropically etched to form a surface. On top of this,
・Heat the surface of the 81 substrate with the 7-shaped grooves formed in this way in an atmosphere of H2, O gas containing 02 gas to form a S:lO, film inside the 7-shaped grooves and on the Si substrate surface. After that, the SiO2 film adhering to Sj and the substrate surface is selectively etched and removed except for the inside of the single-shaped groove.

And the Si defined by the 5in2 film with 7-shaped grooves like this
Processes C and L by introducing impurities for semiconductor element formation into the substrate surface.
The company was manufacturing semiconductor devices such as SI.

However, the above-mentioned 7-shaped 5102 film for isolation between elements is
When formed on a substrate, the 7-shaped 5in2 film is Sj
- The area tends to expand as it reaches the surface of the substrate, so the area of the 5j-02 film for element isolation on the Si substrate surface increases, making it difficult to integrate a large number of semiconductor elements on one Si substrate. This has resulted in the disadvantage that it cannot be done.

(cl) OBJECT OF THE INVENTION The present invention eliminates the above-mentioned drawbacks and provides C! , 5-10 for isolation between elements used in the process of manufacturing semiconductor devices such as LSI
．． The object of the present invention is to provide a novel method for forming a Si, O, and film for isolation between elements, which allows the film to be formed in a small area.

(e) Structure of the Invention Si for device isolation of the present invention to achieve the above object
, O, film formation method is to form an insulating film in a predetermined pattern on a silicon substrate, further form a silicon epitaxial layer on the substrate to fill in the gaps between the insulating films, and then oxidize the surface of the epitaxial layer. After that, a resist film is formed on the substrate to a thickness that buries the protruding silicon epitaxial layer formed on the insulating film of the predetermined pattern. This method is characterized in that after drying the oxide film, the silicon dioxide film remaining on the epitaxial layer is further removed.

(f') Embodiment of the Invention An embodiment of the invention will be described below in detail with reference to the drawings. As shown in Fig. 2, first, a chemical paper deposition (OVD) method using silane (SiH) gas and oxygen (02) gas or a thermal oxidation method of the substrate was performed on an N-type 81 substrate ll. After forming the Sin film, a photoresist film with a predetermined pattern is formed on the substrate, and a 5j-02 film 12 with a predetermined pattern is formed by plasma etching or the like using the photoresist film as a mask.

Next, the substrate was inserted into a reaction tube, a mixed gas of silicon tetrachloride (Sice4) and hydrogen (CHg) was introduced into the reaction tube, and the reaction tube was heated to reduce S:1c74 with hydrogen. As shown in the figure, a single crystal silicon epitaxial layer 13 is formed so as to be buried between the 5102 films described above. At this time, the Si epitaxial μ layer also grows on the 8102 film 12 described above, and the Si layer forms a convex shape on the 5in2 film.

Next, the surface of the substrate is thermally oxidized to form a Si,O2 film 14 on the entire surface. This 5102 film 14 functions as a protective film to protect the surface of the 81-layer pitaxial layer from damage when etching the photoresist film in a later step.

15 is applied to fill the spaces between the 81 layers 13 which have grown in a convex shape on the 8102 film 12 described above, so that the surface of the substrate is gently flattened.

Thereafter, the reading substrate was placed on the substrate mounting stand in the reaction tube, and carbon tetrafluoride (CF4) gas was added at 95% by volume, Oi! Gas is 5% by volume
Introduced a mixed gas into the reaction tube, and connected it between the electrode in the reaction tube and the substrate installation stand with an output of 1.2 KW and a frequency of 13.56 MH.
By applying a high frequency voltage of z, the photoresist film 15 on the surface of the substrate and the 5102 film 14 locally protruding on the 8102 film 12 for element isolation are simultaneously removed by plasma etching. Here, by using the above-mentioned mixed gas of OF, 4 gas and 02 gas, the photoresist film 12 and the protruding S
In, film 14 is etched and removed at approximately the same rate. The state formed in this manner is shown in FIG.

As shown in the figure, the Si for element isolation and the sxo, #14 that were formed protrudingly on the film 12 are also removed, resulting in a flat state. .

Furthermore, by etching and removing the remaining epitaxial layer 18 with a mixed solution of molybdenum (NH4F), a 5102 film 12 for isolation between elements with a flat surface and a small area is formed as shown in FIG. By introducing impurities for semiconductor element formation into the region defined by this Sing film 12, highly integrated semiconductor devices such as C, LSI, etc. can be formed. .

(To) Effects of the Invention As described above, according to the method of the present invention, a 5in2 film for isolation between elements can be formed on an 81 substrate in a minute area, so the degree of integration of semiconductor devices formed on the substrate is improved. Moreover, since the substrate surface is formed flat, there is no fear that the wiring connecting between the semiconductor elements will be disconnected after the semiconductor elements are formed, and a highly reliable semiconductor device can be obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a conventional method for manufacturing a semiconductor device, and FIGS. 2 through 6 are cross-sectional views showing an embodiment of the method for manufacturing a semiconductor device according to the present invention. In the figure, 1 and 11 are 81 substrates, 2. ■5 is photoresinut film, 8 is 7-shaped groove, 4 is V-shaped groove side, 12°14 is 51
02 film, 18 indicates a Si epitaxial layer. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 4 Figure 6

Claims (1)

[Claims] An insulating film with a predetermined pattern is formed on a silicon substrate, and a silicon epitaxial layer is further formed on the substrate to fill in the gaps between the insulating films.Then, after oxidizing the surface of the epitaxial layer, the insulating film with a predetermined pattern is formed on the silicon substrate. A resist film is formed on the substrate to a thickness that buries the protruding silicon epitaxial layer formed thereon, and then, after etching the resist film and the protruding oxide film of the silicon epitaxial layer, a resist film remains on the epitaxial layer. 1. A method for forming an isolation film between elements, characterized by removing a silicon dioxide film that is