KR980012264A - Pulley recessed LOCOS isolation method - Google Patents

Abstract

Disclosed is a pulley recessed LOCOS method capable of achieving a uniform recess depth.

A semiconductor manufacturing method for forming a device isolation film by a pulsed recessed LOCOS technique, comprising: forming a pad oxide film, a nitride film and an oxide film on a semiconductor substrate; Further forming a polysilicon film on the resultant to a depth for etching the semiconductor substrate; Forming a photoresist on the entire surface of the substrate, sequentially patterning the oxide film, the nitride film, and the pad oxide film through a photolithography process to define an active region; Removing the photoresist film; And etching the polysilicon film and simultaneously etching the semiconductor substrate. The present invention also provides a method of manufacturing a pulley recessed LOCOS method capable of obtaining a uniform recess depth. Therefore, in the pulley recessed LOCOS method according to the present invention, the depth at which the substrate silicon is etched depends on the thickness of the highest polysilicon, and since the polysilicon and the oxide film have a high selectivity of 10: 1 or more, It is possible to secure a high recess depth uniformity in comparison with the conventional method.

Description

Pulley recessed LOCOS isolation method

The present invention relates to a fully reclaimed LOCOS isolation method and relates to a pulley recessed LOCOS isolation method that achieves a uniform recess depth.

Recently, the element isolation region of a semiconductor device is mainly formed by using a local oxidation of silicon (LOCOS). Here, the device isolation method using LOCOS is a method of locally growing a thick field oxide layer by a thermal oxidation process between active regions where devices are to be formed. However, as semiconductor devices become more highly integrated, LOCOS technology, which is a technology for separating devices and devices, faces technological limitations, and pulley recessed LOCOS technology is being developed to overcome these limitations.

1A to 1B are cross-sectional views illustrating a conventional pulley recessed LOCOS method.

The pulley-recessed LOCOS is formed by laminating a pad oxide film 3 and a silicon nitride film (SiN: 5) on a substrate silicon 1 and patterning it as shown in FIG. 1A. Subsequently, as shown in Fig. 1B, the substrate silicon 1a is etched by a predetermined amount. Thereafter, when the thermal oxide film is grown, the separation interval between the devices increases, and the device isolation resistance is improved. Due to these advantages, various modified pulley recessed LOCOS device isolation techniques have recently been proposed.

However, since the recessed LOCOS technique etches the substrate silicon before the formation of the thermal oxide film by the dry or wet etching method, the recessed depth can not be controlled by time. Since the time-controlled etching method is sensitive to the state of the apparatus and the etching rate, the uniformity is significantly lower than the etching method in which the underlying film having the etching selectivity is held at the end point. The recessed depth non-uniformity in the pulley recessed LOCOS results in non-uniformity of the bird's beak encroachment, and in shallow recess depths the device isolation resistance is poor and in deep depths the bird's beak There is a problem such as excessive growth.

SUMMARY OF THE INVENTION The present invention provides a pulley recessed LOCOS method capable of solving the problems of the prior art of pulley recessed LOCOS and achieving a uniform recess depth.

Figures 1a-1b are cross-sectional views illustrating a conventional pulley recessed LOCOS process.

Figures 2a through 2c are cross-sectional views for explaining the pulley recessed LOCOS method according to the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS

11: substrate silicon 13: pad oxide film

15: silicon nitride film 17: oxide film

19: polysilicon film 21: photoresist film

According to an aspect of the present invention, there is provided a semiconductor manufacturing method for forming a device isolation layer using a pulsed LOCOS technique, comprising: forming a pad oxide layer, a nitride layer, and an oxide layer on a semiconductor substrate; Further forming a polysilicon film on the resultant to a depth for etching the semiconductor substrate; Forming a photoresist on the entire surface of the substrate and sequentially patterning the oxide film, the nitride film, and the pad oxide film through a photolithography process to define an active region; Removing the photoresist film; And etching the polysilicon film and simultaneously etching the semiconductor substrate. The present invention also provides a method of manufacturing a pulley recessed LOCOS method capable of obtaining a uniform recess depth.

The oxide film may be grown as a thermal oxide film or deposited by CVD.

When the semiconductor substrate is etched, the top polysilicon is etched together with the etch stopper in the oxide film on the nitride film.

The depth at which the semiconductor substrate is etched depends on the thickness of the top polysilicon.

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

FIGS. 2A and 2B are cross-sectional views illustrating a pulley recessed LOCOS method according to the present invention.

A semiconductor device manufacturing method for forming a device isolation film by a LOCOS technique pulley-recessed on a silicon substrate is as follows.

A pad oxide film 13 is grown on the substrate silicon 11 and a silicon nitride film (SiN) for preventing thermal oxidation is laminated. Thereafter, when a thermal oxide film is grown under the condition that an oxide film is grown to 1000 to 3000 angstroms in bare silicon, the oxide film 17 is grown to a thickness of about 50 to 150 angstroms on the silicon nitride film (SiN: 15). In addition to the thermal oxide film growth method, the oxide film may be thinly deposited by CVD. Thereafter, the polysilicon 19 is laminated to a thickness corresponding to the recess depth of the substrate silicon (Fig. 2A)

Next, a photoresist is formed on the entire surface of the substrate, and the oxide film, the nitride film, and the pad oxide film are sequentially patterned through a photolithography process to define active regions and fields (FIG. 2B).

After the pad oxide film is patterned, the photoresist film 21 is removed to form a polysilicon / oxide film / silicon nitride film / pad oxide film / silicon substrate structure. At this time, the substrate silicon is etched to form the recess structure. The polysilicon deposited on the active region is etched together with the underlying oxide film 17a of the polysilicon as an end point, thereby etching the substrate silicon . (Figure 2c)

It is obvious that the present invention is not limited to the above embodiments and that many modifications are possible within the technical scope of the present invention by those skilled in the art.

In the pulley recessed LOCOS method according to the present invention, the depth at which the substrate silicon is etched depends on the thickness of the best polysilicon, and since the polysilicon and the oxide film have a high selectivity ratio of 10: 1 or more, The recess recess depth uniformity can be secured.

Claims (4)

A semiconductor manufacturing method for forming a device isolation film by a pulsed recessed LOCOS technique, comprising: forming a pad oxide film, a nitride film and an oxide film on a semiconductor substrate; Further forming a polysilicon film on the resultant to a depth for etching the semiconductor substrate; Forming a photoresist on the entire surface of the substrate and sequentially patterning the oxide film, the nitride film, and the pad oxide film through a photolithography process to define an active region; Removing the photoresist film; And etching the semiconductor substrate at the same time as etching the polysilicon film to obtain a uniform recess depth. The pulley recessed LOCOS method according to claim 1, wherein the oxide film can be grown as a thermal oxide film or can be deposited by CVD. The LOCOS method as claimed in claim 1, wherein the etch stop is performed on the oxide film on the nitride film together with the top polysilicon etched when the semiconductor substrate is etched. 2. The pulley recessed LOCOS method of claim 1, wherein the depth at which the semiconductor substrate is etched depends on the thickness of the top polysilicon. ※ Note: It is disclosed by the contents of the first application.