JPS61154144A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve insulating characteristics, by providing a form, which is analogous with a polycrystalline silicon region and extended outward from a silicon oxide film on the side wall of polycrystalline silicon by a specified distance as a part of the silicon oxide film, which is formed on the surface of a semiconductor substrate. CONSTITUTION:On silicon semiconductor susbtrate 11, a silicon oxide film 12, a silicon nitride film 13 and a silicon oxide film 20 are formed. Thereafter a photoresist pattern 14 is formed. Etching is performed by an RIE method sequentially, and a groove 15 is formed. Then, with the resist mask 14 as a mask, the silicon oxide film 20 is etched. The side surface is etched. With the silicon nitride film 13 as a mask, the surface of the groove is selectively oxidized, and a silicon oxide film 16 is formed. Then, with the silicon oxide films 16 and 20 as masks, the silicon nitride film 13 is partially etched. The groove 15 is buried by a polycrystalline film. Then the surface is flattened, and the silicon oxide film 20 is removed. Thereafter, with the remaining silicon oxide film 20 is removed. Thereafter, with the remaining silicon nitride film 13 as a mask, the surface of the substrate and the surface of the polycrystalline silicon film 17 are oxidized, and a silicon oxide film 18 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to a semiconductor device and a method for manufacturing the same, and more particularly to a semiconductor device in which elements are separated by a buried polycrystalline silicon film and a method for manufacturing the same.

[Conventional technology]

Conventionally, R, D, Rumg, etc. have been used as manufacturing methods for forming element isolation using polycrystalline silicon films using IEDM (Inter
nationaI Electron Devices
Meeting) Published on page 237 of 82-
This method is mainly used. The key point of this manufacturing method is to form a triple film of silicon oxide film and silicon nitride film on a silicon substrate, and then apply a silicon oxide film or halide pattern by CVD method as a mask material for forming silicon grooves on this 2m film. 2 m using the mask material.
A structure is formed by etching the base and silicon substrate, a silicon oxide film is formed on the surface of the film, a trench is filled with a polycrystalline silicon film and the surface is flattened, and the surface of the polycrystalline silicon film is oxidized. - It consists of the following steps.

A conventional element isolation structure based on buried polycrystalline 7-resonance knitting and its manufacturing method will be explained with reference to FIGS. 2(a) to 2(d). FIG. 2(1) shows a silicon oxide film 12 on a semiconductor substrate 11. After forming the silicon nitride film 13t, a photoresist pattern 14 is formed, and the photoresist pattern 14t is masked to form the silicon nitride film 13. A silicon oxide film 12 and a silicon substrate 11 are sequentially etched to form grooves 15. Next, as shown in FIG. 2(b), the photoresist is removed and the groove surface is oxidized to form a silicon oxide film. Next, as shown in FIG. 2(C), the substrate is buried with a polycrystalline silicon film 17 and planarized.

Next, as shown in FIG. 1(d), the silicon nitride film 13
A polycrystalline silicon film 18 is formed by selectively degrading the polycrystalline silicon film 18 using the mask as a mask.

In this case, the entire circumference of the buried polycrystalline silicon film is covered with an oxide film to complete the next element isolation region.

[Problem that the invention seeks to solve]

In the device isolation method using the buried polycrystalline silicon film described above, the silicon nitride film used as an intensification mask material used when selectively oxidizing the silicon surface is again used to selectively oxidize the surface of the polycrystalline silicon film in which II is buried. I'm using it. For this reason, the oxide film seams formed by these two selective oxidations are removed from the bird's head (bir's head) formed by the selective oxidation.
It has a shape in which d he @ d) are connected9, and the European membrane thickness is thinner in the large ring than in other places. As a result, this thin%
1-Charges are injected into the polycrystalline silicon film for insulation isolation through the region of the dielectric film, and an inversion layer is formed on the surface of the substrate beneath the film, resulting in deterioration of the insulation properties.
I'm doing M.

As a countermeasure, the grooves were filled with polycrystalline silicon, and after planarization, a photo process was performed to partially remove the silicon nitride film, which is a mask material for selective oxidation. A method of selectively oxidizing the waist coat has been proposed, but using this method requires an extra photo process step, making the process longer and requiring a margin for mask alignment. Rad's 211 to wider areas and partially removed parts and birds!
! This method has a serious drawback because weak parts are formed in certain places and it is difficult to form a uniform oxide film.

Therefore, the present invention has been made in view of the above-mentioned drawbacks.
It is an object of the present invention to provide a semiconductor device having an element IIk region and a method for providing a semiconductor device having an element IIk region, which is uniformly oxidized to necessary regions except for problematic thin oxide film regions without increasing the number of OTO processes. do.

[Means for solving problems]

The first aspect of the present invention includes a polycrystalline silicon region buried in a semiconductor substrate, a silicon encapsulant formed around the entire periphery of the polycrystalline silicon region, and The silicon oxide film portion formed on the surface of the semiconductor substrate has a shape extending outward by a certain distance from the silicon oxide film on the polycrystalline silicon sidewall in a manner similar to the polycrystalline silicon region. is configured.

Further, the method for manufacturing a semiconductor device according to the second invention of the present invention includes:
Silicon oxide 11 on the surface of a silicon semiconductor substrate! , a step of forming a triple film of a silicon nitride film and a silicon oxide film, a step of forming a photoresist pattern on the 3N layer, and a step of etching and removing the triple layer using the resist as a mask, and then repeating the steps again. etching the surface of the silicon substrate exposed as the photoresist mask to form holes or damage;
Thereafter, a step of etching the silicon oxide film again using the resist described in III as a mask, a step of forming a silicon oxide film on the surface of the hole or groove, and a step of etching the silicon nitride film using the 7-recon oxide film as a mask. ◎ [Example] Below Embodiments of the present invention will be described with reference to the drawings. FIGS. 1--(d) are cross-sectional views shown in order of step 1 to explain an embodiment of the present invention. An embodiment of the present invention can be manufactured by the following steps.

First, as shown in FIG. 1(a), an oxide film 12 with a thickness of about 500 layers is formed on a silicon semiconductor substrate 11 by thermal oxidation, and a silicon nitride film 13 is formed by CVD@ with a thickness of about 1100 layers. The film is formed to a thickness of about 200 mm, and then coated by KCVD to a thickness of about 200 mm.
After forming a silicon oxide film 20 with a thickness of 0.00000, a resist pattern 14 is formed by a photo process method, and this resist pattern 14'fi--a silicon oxide film 20.degree. silicon nitride film 13. Silicon oxide [
12 and silicon substrate 11 are etched by the RIE method to form grooves 15 with a depth of approximately 4 μm.

Next, as shown in Figure 1(b), a silicon oxide film 2 (one etched, approximately α5 μm thick) was used as a mask for the resist film 14t.
Etch the sides with O41I&.

Next %I! As shown in FIG. 1C, the resist is removed and the groove surface is selectively modified using the silicon nitride film 13 as a mask, and a silicon plated film 16t is formed with a thickness of approximately α2 μm. Next - silicon oxidation [16-.

20f: Partially etching silicon nitride ml as a mask.

As shown in FIG. 1(d), the groove 15 is filled with polycrystalline silicon WXK, then planarized, and removed to form a silicon oxide film 20. Using the remaining silicon nitride film 13 as a mask, the substrate surface is Then, the surface of the polycrystalline silicon film 17 is made thinner, and silicon oxide [18] is formed with a thickness of approximately α6 μm (D film thickness. At this time, the thin oxide film corresponding region 19a does not become thinner and is separated from the oxide film on the polycrystalline silicon film. They are almost the same thickness.

As described above, the structure of the present invention shown in Mil1 diagram (d) is obtained.

As described in detail above, the present invention is directed to a mask material for conventional O selective oxidation.

After forming a new silicon oxide layer and etching the silicon nitride layer, silicon nitride film and silicon substrate using the same resist to form a silicon nitride film pattern, etching the silicon oxide film tI11 surface, The silicon is similar to the silicone film pattern to form a silicone film pattern. The nitride film pattern and oxide film pattern thus formed are used as a mask pattern for selective oxidation of the groove surface and a mask pattern for selective oxidation of the polycrystalline silicon film surface, respectively. As a result, it is possible to eliminate the thin region of the oxide film on the polycrystalline silicon film in the conventional method, and as a result, a semiconductor device having an element isolation region with improved insulation properties can be obtained. According to the present invention, it is possible to achieve uniform thickness oxidation in the necessary area without increasing the number of photoprocessing methods and without creating a thin i-region in the oxide film on the polycrystalline silicon area, which is a problem. It has a device isolation region throughout the film, and therefore a semiconductor iron layer with improved characteristics can be obtained.

[Brief explanation of drawings]

Figures 1 (1) to (d) are cross-sectional views showing steps to explain one embodiment of the present invention, and Figures 2 (1) to (d) are elements using conventional buried polycrystalline silicon films. FIG. 2 is a cross-sectional view showing a process step for explaining a semiconductor device having an isolation region and a method for manufacturing the same. 11...Silicon semiconductor substrate, 12.16,1
8゜20...Silicon oxide film, 13...
・Silicon nitride film, 14...photoresist,
15... Silicon book, 17... Polycrystalline silicon film, 19... Thin oxide film region, 19a
...--A region compatible with thin Vh plating film. Kudzu l Charitable bribe 2 evil

Claims (2)

[Claims] (1) It has a polycrystalline silicon region buried in a semiconductor substrate and a silicon oxide film formed to surround the entire periphery of the polycrystalline silicon region, and the silicon oxide film is formed on the surface of the semiconductor substrate. A semiconductor device characterized in that the portion has a shape extending outward from the silicon oxide film of the polycrystalline silicon sidewall by a certain distance in a similar manner to the polycrystalline silicon region. (2) A step of forming a triple film of a silicon oxide film, a silicon nitride film, and a silicon oxide film on the surface of a silicon semiconductor substrate, a step of forming a photoresist pattern on the triple film, and a step of forming a photoresist pattern using the resist as a mask. After etching and removing the film, etching the exposed silicon substrate surface again using the photoresist as a mask to provide a hole or groove; and then etching the silicon oxide film again using the resist as a mask; forming a silicon oxide film on the surface of the hole or groove; etching the silicon nitride film using the silicon oxide film as a mask; burying the hole or groove with polycrystalline silicon; and remaining silicon nitride film. oxidizing a substrate surface and a polycrystalline silicon surface using as a mask.