KR19990004622A - Device Separating Method of Semiconductor Device - Google Patents

Abstract

The present invention relates to a method for forming a device isolation film of a semiconductor device, wherein the stress generated when the device isolation oxide film is formed has less influence on the semiconductor substrate, and the exposed polysilicon is consumed as an oxide film during the oxidation process, making it easy to form an oxide film. The portion where the active element is to be formed is not affected by the buzz big generated during the oxidation process, the probability of occurrence of the leakage current path between cells caused by the stress is reduced, and the device isolation oxide film during the etching process to form the gate pattern. Since the shape of is not abrupt, it is possible to reduce the damage of the gate oxide film generated during etching, thereby forming a small device isolation layer having excellent electrical characteristics and reliability.

Description

Method of forming device isolation film of semiconductor device

The present invention relates to a method for forming a device isolation film of a semiconductor device, in particular, to reduce the effect of stress on the semiconductor substrate when forming the device isolation oxide film, and to reduce the loss of the semiconductor substrate consumed by the device isolation oxide film, excellent electrical characteristics, buzz The present invention relates to a technology for forming a highly reliable device isolation oxide film without a bird's beak.

In general, a semiconductor device is composed of an active region in which devices such as a transistor or a capacitor are formed, and an isolation region separating the active regions so that the operation of the devices does not interfere with each other.

Recently, with the trend toward higher integration of semiconductor devices, efforts have been made to reduce the area of device isolation regions, which occupy a large area in semiconductor devices.

As a method of manufacturing the device isolation region, a conventional local oxidation of silicon (LOCOS) method of thermally oxidizing a semiconductor substrate using a nitride film pattern as a mask, or a trench is formed in a semiconductor substrate and embedded in an insulating material. The trench separation method is used. Among them, the LOCOS method is widely used because of its relatively simple process, but the device isolation area is large and bird's beak is formed on the interface to prevent lattice defects caused by substrate stress. There is a disadvantage that occurs.

Looking at the manufacturing method of the LOCOS field oxide film as follows.

First, the surface of the semiconductor substrate is thermally oxidized to form a pad oxide film, a nitride film is formed on the pad oxide film, and a nitride film pattern is formed to expose a predetermined portion to the device isolation region of the semiconductor substrate. The field oxide film is formed by thermally oxidizing a semiconductor substrate to a predetermined thickness using a thermal oxidation mask.

In the conventional LOCOS field oxide film, oxygen penetrates into the semiconductor substrate boundary portion between the active region and the field oxide film to form an inclined surface called Buzzvik.

Since the stress is applied to the semiconductor substrate by the Burjvik, lattice defects are generated, so that leakage current is increased and reliability of the device is decreased, and the area of the active area is reduced, making it difficult to integrate the device.

In the method of forming a device isolation layer of a semiconductor device according to the prior art as described above, the size of the device isolation layer decreases as the degree of integration of the semiconductor device increases, but the space margin between contact holes decreases, so the problem of Buzz Big is to secure a desired active region. There is this.

In order to solve the problems of the prior art, the device isolation film of a semiconductor device improves the reliability of the gate oxide film by reducing the stress concentrated at both ends of the device isolation film when the device isolation film is formed, and reduces the leakage current between cells. The purpose is to provide a formation method.

1A to 1G are cross-sectional views illustrating a method of forming an isolation layer in a semiconductor device in accordance with a first embodiment of the present invention.

2A to 2C are cross-sectional views illustrating a method of forming an isolation layer in a semiconductor device in accordance with a second embodiment of the present invention.

3A to 3D are cross-sectional views illustrating a method of forming an isolation layer in a semiconductor device in accordance with a third embodiment of the present invention.

Explanation of symbols for main parts of the drawings

11: semiconductor substrate 13: complete layer oxide film

15 polycrystalline silicon 17 first anti-oxidation nitride film

19 photosensitive film pattern 21 second anti-oxidation nitride film

22 second anti-oxidation nitride film spacer 23 third anti-diffusion nitride film

A device isolation film forming method of a semiconductor device according to the present invention for achieving the above object, the step of depositing a buffer oxide film on the semiconductor substrate, the step of depositing polycrystalline silicon on the buffer oxide film, and the first on the polycrystalline silicon A process for forming an anti-oxidation nitride film, etching the anti-oxidation nitride film in a portion intended as an isolation region, forming a second anti-oxidation nitride film on the structure, and the second anti-oxidation nitride film And etching the entire surface to form a second anti-oxidation nitride film spacer and simultaneously exposing the polysilicon, and performing an oxidation process in a subsequent process to form a device isolation oxide film.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1A to 1G are cross-sectional views illustrating a method of forming a device isolation foil of a semiconductor device in accordance with a first embodiment of the present invention.

First, a buffer oxide film 13 is formed on the semiconductor substrate 11.

Next, polycrystalline silicon 15 is formed on the buffer oxide film 13.

Next, a first diffusion barrier nitride film 17 is formed on the polysilicon 15.

Then, a photosensitive film (not shown) is coated on the first diffusion preventing nitride film 17.

Subsequently, the photosensitive film is exposed and developed using an element isolation mask to form a photosensitive film pattern 19. (FIG. 1A)

Next, the first diffusion barrier nitride layer 17 is etched using the photoresist pattern 19 as an etching mask. (FIG. 1B)

Next, the photoresist pattern 19 is removed.

Subsequently, a second diffusion preventing nitride film 21 is formed on the structure. (FIG. 1C)

Thereafter, the second diffusion preventing nitride film 21 is etched entirely to form a second diffusion preventing nitride film spacer 22. (FIG. 1D)

Next, a part of the polysilicon 15 is inclined dry etching. (FIG. 1E)

Then, the polysilicon 15 is dry etched obliquely until the buffer oxide film 13 is exposed. (FIG. 1F)

The buffer oxide film 13 and the semiconductor substrate 11 having a predetermined thickness are etched. (Fig. 1g)

Thereafter, an oxidation process is performed to form an element isolation oxide film (not shown).

2A to 2C are cross-sectional views illustrating a method of forming a device isolation film of a semiconductor device in accordance with a second embodiment of the present invention.

Meanwhile, a part of the polysilicon 15 is subjected to an isotropic wet etching process in a subsequent process to the structure shown in FIGS. 1A to 1D of the first embodiment. (FIG. 2A)

Next, the polysilicon 15 is etched by the entire surface etching process until the buffer oxide film 13 is exposed. (FIG. 2B)

Next, the buffer oxide film 13 and the semiconductor substrate 11 are etched by an isotropic wet etching process. (FIG. 2C)

Thereafter, an oxidation process is performed to form an element isolation oxide film (not shown).

3A to 3D are cross-sectional views illustrating a method of forming an isolation layer in a semiconductor device according to a third embodiment of the present invention.

Further, in a subsequent process of the structure shown in Figs. 1A to 1D of the first embodiment, the entire surface etching process is performed to etch a predetermined thickness of the polysilicon 15.

Next, a third diffusion preventing nitride film 23 is deposited on the entire structure. (FIG. 3A)

Next, the third diffusion preventing nitride film 23 is etched entirely to form a third diffusion preventing nitride film 23 spacer. (FIG. 3B)

Subsequently, all of the polysilicon 15 is etched using the third diffusion preventing nitride film 23 as an etch barrier, and the buffer oxide film 13 is etched. (FIG. 3C)

Thereafter, the semiconductor substrate 11 is etched by a predetermined thickness. (FIG. 3D)

Then, an oxidation process is performed to form a device isolation oxide film (not shown).

As described above, in the method of forming a device isolation film of a semiconductor device according to the present invention, the stress generated when the device isolation oxide film is formed has less influence on the semiconductor substrate, and the exposed polysilicon is consumed as an oxide film during the oxidation process. It is easy to form, and the part where the active element is to be formed is not affected by the buzz big generated during the oxidation process, the probability of occurrence of the leakage current path between cells caused by the stress is reduced, and the etching process for forming the gate pattern Since the device isolation oxide film is not abruptly formed, the damage of the gate oxide film generated during the etching may be reduced, thereby forming a small device isolation film having excellent electrical characteristics and reliability.

Claims (7)

Depositing a buffer oxide film on the semiconductor substrate, depositing polycrystalline silicon on the buffer oxide film, forming a first anti-oxidation nitride film on the polycrystalline silicon, and forming a portion of the predetermined region as an isolation region Etching the anti-oxidation nitride film, forming a second anti-oxidation nitride film on the structure, and etching the second anti-oxidation nitride film over the entire surface to form a second anti-oxidation nitride film spacer and simultaneously exposing the polysilicon. And forming a device isolation oxide film by performing an oxidation step in a subsequent step. The method of claim 1, wherein after the predetermined thickness of the polysilicon is etched, a nitride film is deposited. The method of claim 2, wherein the nitride film is etched entirely, the polycrystalline silicon, the buffer oxide film, and the semiconductor substrate having a predetermined thickness are etched, and then an oxidation process is performed. The method of claim 1, wherein the polysilicon, the buffer oxide film, and the semiconductor substrate having a predetermined thickness are etched in an inclined manner and then subjected to an oxidation process. The method of claim 1, wherein a portion of the polysilicon is removed by an isotropic wet etching process, all of the polysilicon is removed by a dry etching process, the buffer oxide film and the semiconductor substrate having a predetermined thickness are removed by an isotropic etching process, and then an oxidation process A device isolation film forming method of a semiconductor device, characterized in that for performing. The method of claim 1, wherein the oxidation process is performed by a wet or dry oxidation process. The method of claim 1, wherein the oxidation process is performed by a wet or dry oxidation process followed by a dry or wet oxidation process.