JPS6180833A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To suppress the exposure of a corner as well as to improve the characteristics of a transistor by a method wherein an insulating film is buried in the recessed part of an Si substrate in such a manner that it is protruded from the Si surface at least other than the recessed part. CONSTITUTION:A groove of approximately 0.7mum is depth is formed on an Si substrate 1 by performing a reactive ion etching (RIE) using an SiO2 film 4 as a mask. Then, after the SiO2 film is removed, an insulating film BPSG6, containing boron and phosphorus, for example, of 1.0mum or thereabout is deposited, and impurities are diffused on the Si substrate 1 by performing a heat treatment. Then, after the BPSG6 is removed, a CVD-SiO28, which is an insulating film, of 1.2mum or thereabout is deposited. Subsequently, the surface of the above is flattened using a fluidity film 9 resist, and an etching back is performed using the reactive ion etching of a resist and the CVD-SiO28. The end point is set at the place where the surface of a poly-Si3 appears. When the poly-Si3 is removed, an insulating film is formed protuberatedly on the recessed part of the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a semiconductor device and a method for manufacturing the same.

[Technical background of the invention and its problems]

Conventionally, in the insulating V-embedded device isolation method, the insulating film in the isolation region is etched in a hydrofluoric acid treatment after the device isolation process is completed, and the corners of the device region are It will be exposed. In this way (when a corner in the element region is exposed, the electric field concentration at the corner becomes stronger,
This leakage current, which increases the leakage current, deteriorates the characteristics of the transistor and further reduces the yield.

LObject of the Invention] The object of the present invention is to improve transistor characteristics by preventing corner protrusion due to regression of insulation in the element isolation region (field region) due to hydrofluoric acid treatment after formation outside the element. An object of the present invention is to provide a semiconductor device for filtering and a method for manufacturing the same.

[Summary of the invention]

The present invention suppresses the exposure of the corners by embedding the pupil-stopping film in the recessed portions of the Si substrate so that it is raised higher than at least the Si surface other than the recessed portions, thereby preventing deterioration of the transistor.

〔Effect of the invention〕

According to the present invention, the insulating film embedded in the 8i substrate recess is formed to be raised higher than the Si surface other than the recess (first
figure). This prevents the corners of the recessed portions of the Si substrate from being exposed during hydrofluoric acid treatment such as oxidation pretreatment. As a result, the deterioration of transistor characteristics was significantly suppressed, the reliability of the cell circuit was improved, and yields were dramatically improved.

[Embodiments of the invention]

A disaster example of the present invention will be explained using FIGS.

First of all, the surface orientation of the S'' substrate (1), for example, p iJl (
Prepare a substrate of 100) and apply a thermal oxide film (2) of, for example, 10
0 (about 1 is formed. Next, for example, phosphorus-doped poly
After debossing -8i (3) by about 4000A, for example, S, i 0゜lf! <41 is formed to approximately 4000A. Next, patterning is performed using a normal photoetching process to obtain a structure as shown in FIG.

(4) and poly-8if31 are etched anisotropically, for example, by reactive ion etching. 310° film in the sky 2), +41 womas / 4 cops o
I y -8i (31-dimensional IC etching,
diO, [poly”-
Invade 8it31. If a ``0* film 12) is arranged on the mask of the dawn resist 151, it is etched with Ig.

SiO!, the sickle that removed one resist (5) from Z! Suggestion (
Using 41 as a mask, a temporary Si4 layer is placed and etched using RIB to form 4 with a depth of about 0.7 μm, for example. 8 for dogs
If an insulating film containing poron and phosphorus [3P S G+6] is deformed by about 1.0 μm using a sickle from which the i011 risk (4) has been removed, and heat treatment is performed at 950°C for 30 minutes in N, S
Impurities diffuse into i Reika (1). Absolutely the above BPSG1
After removing 61, deposit an insulating film (CVD-8in, @) with a thickness of 1.2 μm, for example.
) For example, planarize with resist and create resistor h and CVD-8.
i0. (Reaction 1+ for Si: Etch back using ion etching under conditions where the etching rate of SiO is faster than the etching rate of the resist. The point is where the surface of poly y-8i (3) appears. The structure so far e is shown in Figure 2 C-.Next, p
If oly-8i f31 is removed, an insulating layer (8) will be formed in the Si substrate concavity as shown in Figure 2.Furthermore, i'j3@129'' will be formed in the lateral direction of the concave portion. In this embodiment, for example, polysilicon was used as the film (3) to be etched isotropically, but it may also be silicon oxide.

Furthermore, boron diffusion 1 to (7) is B P 8 G161
Although it is formed by a heat treatment process after debossing, the same effect can be obtained by ion implantation.

In addition, the depth of the recess is d, and the rise of the field oxide film is 31, and the spread to the periphery is b1 field.

[Brief explanation of drawings]

Figures 1 and 2 (at to -) are cross-sectional views for explaining the present invention, and Figures 3 and 3 are cross-sectional views for explaining a conventional example.

Claims (4)

[Claims] (1) A recess with a depth d is formed in the element isolation region on the surface of the semiconductor substrate, and a field oxide film is present in the recess, protruding by an amount a from the silicon substrate surface and expanding by an amount b at the periphery,
The above a and b are c<a<d/2, c<b<d, where c is the amount of film reduction after the field oxide film is formed.
A method for manufacturing a semiconductor device, characterized in that each is represented by /2. (2) The semiconductor according to claim 1, further comprising the step of forming an insulating film extending around the periphery by a normal photolithography technique when embedding the insulating film in the recess. Method of manufacturing the device. (3) a step of forming a first film on a semiconductor substrate, a step of stacking a second film, and a step of further forming a third film;
etching the third film by photolithography; further etching the second mask using the third film as a mask; and etching the second film in the same shape as the third film. a step of etching the first insulating film using a third film as a mask; a step of etching the Si substrate using at least the first film as a mask to form a recess; and a step of forming a third film. forming a recess in the Si substrate by forming and etching a fluid film on the third film; and depositing a fourth insulating film on the entire surface after removing the third film. 2. The method of manufacturing a semiconductor device according to claim 1, further comprising the steps of: etching at least a portion of the fourth insulating film to bury at least the Si recess. (4) The semiconductor according to claim 3, wherein the first and third films are silicon oxide films, and the second film is a silicon nitride film or a poly-Si film. Method of manufacturing the device.