KR19980056161A - Device Separator Formation Method of Semiconductor Device - Google Patents

Abstract

The present invention provides a method for forming an isolation layer of a semiconductor device capable of minimizing stress applied to a substrate during a thermal oxidation process for forming an isolation layer using a recess of a silicon layer. Sequentially forming; Etching the nitride film and the pad oxide film to expose a predetermined portion of the substrate; Forming a polysilicon film on the entire surface of the substrate; First oxidizing the polysilicon film to form an oxide film on a predetermined portion of the polysilicon film; Etching the polysilicon film using the oxide film as an etching mask and recessing the substrate to a predetermined depth; And forming a field oxide film by second oxidizing the recessed substrate, wherein the oxide film is formed at the grain boundary of the polysilicon film during the first oxidation process.

Description

Device Separator Formation Method of Semiconductor Device

The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of forming a device isolation layer of a semiconductor device capable of minimizing stress applied to a substrate during a thermal oxidation process for forming a device isolation layer using a recess of a silicon film.

ISOLATION technology is an integrated device fabrication function that separates the individual devices constituting the integrated device from each other electrically and structurally so that each device can independently perform a given function without interference from adjacent devices. It is a technique to grant.

1A through 1C are cross-sectional views illustrating a method of forming a device isolation layer of a conventional semiconductor device using LOCOS (LOCal Oxidation of Silicon) technology.

First, as shown in FIG. 1A, a pad oxide film 2 is formed on the silicon substrate 1 to relieve stress on subsequent nitride films, and then a nitride film 3 is formed thereon.

As shown in FIG. 1B, the nitride film 3 and the pad oxide film 2 are patterned by a photolithography and etching process to form a predetermined mask pattern for defining active regions and device isolation regions.

As shown in FIG. 1C, a field oxide film 4 is formed on the exposed substrate 1 by performing a thermal oxidation process using the mask pattern.

Then, although not shown, the nitride film 3 and the pad oxide film 2 are removed, respectively.

However, in the conventional method of forming a device isolation film, a significant stress is applied to the substrate during the growth of the field oxide film by the thermal oxidation process, thereby deteriorating the electrical characteristics of the device.

Accordingly, the present invention has been made in view of the above problems, and provides a method of forming a device isolation layer of a semiconductor device capable of minimizing stress applied to a substrate during a thermal oxidation process for forming a device isolation layer using a recess of a silicon film. Has its purpose.

1A to 1C are cross-sectional views sequentially illustrating a method of forming a device isolation film of a conventional semiconductor device.

2A through 2E are cross-sectional views sequentially illustrating a method of forming a device isolation film of a semiconductor device in accordance with an embodiment of the present invention.

3A and 2B are enlarged views of portions (A) and (B) of FIGS. 2C and 2D.

* Description of the symbols for the main parts of the drawings *

11, inductor substrate 12: pad oxide film

13: nitride film 14: polysilicon film

15: oxide film 16: field oxide film

According to an aspect of the present invention, there is provided a method of forming a device isolation film of a semiconductor device, the method comprising sequentially forming a pad oxide film and a nitride film on a semiconductor substrate; Etching the nitride film and the pad oxide film to expose a predetermined portion of the substrate; Forming a polysilicon film on the entire surface of the substrate; First oxidizing the polysilicon film to form an oxide film on a predetermined portion of the polysilicon film; Etching the polysilicon film using the oxide film as an etching mask and recessing the substrate to a predetermined depth; And forming a field oxide film by second oxidizing the recessed substrate.

The oxide film is formed at the grain boundary of the polysilicon film when the first oxidation is fixed.

According to the present invention having the above configuration, as the oxidation process is performed after the substrate is recessed, the stress applied to the substrate during the oxidation process can be minimized.

EXAMPLE

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention.

2A through 2E are cross-sectional views sequentially illustrating a method of forming an isolation layer of a semiconductor device in accordance with an embodiment of the present invention, and FIGS. 3A and 3B are cross-sectional views taken along parts (A) and (B) of FIGS. 2C and 2D. It is an enlarged view.

First, as shown in FIG. 2A, a pad oxide film 12 is formed on the silicon substrate 11 to relieve stress on subsequent nitride films, and then a nitride film 13 is formed thereon. Subsequently, the nitride film 13 and the pad oxide film 12 are patterned by photolithography and etching to form a predetermined mask pattern for defining an active region and a device isolation region.

As shown in FIG. 2B, a polysilicon film 14 is deposited over the structure of FIG. 2A.

As shown in FIG. 2C, the polysilicon film 14 is oxidized by performing a first oxidation process of wet and dry oxidation fixation at a temperature of 900 to 1100 ° C. At this time, a portion A of the oxidized polysilicon film 14 is enlarged as shown in FIG. 3A. That is, as shown in Fig. 3B, the partial oxidation is faster at the grain boundary than the inside of the grain of the polysilicon film 14 in the first oxidation process, so that a predetermined oxide film 15 is formed at the grain boundary.

As shown in FIG. 2D, the polysilicon film 14 is etched to expose the nitride film 13 and the substrate 14 by using the oxide film 15 as an etching mask, and then the exposed substrate 11 is exposed to a predetermined depth. Etch to recess. At this time, a portion B of the polysilicon film 14 and the oxide film 15 on the recessed substrate 11 is enlarged, as shown in FIG. 3B. In addition, a predetermined portion of the nitride film 13 is lost during the recess process of the substrate 11.

As shown in FIG. 2E, a second oxidation process is performed at a temperature of 900 to 1100 ° C. to form a thick field oxide film 16 on the recessed substrate 11. At this time, the polysilicon film 14 above and on both sides of the nitride film 13 is oxidized in the second oxidation process to form a predetermined thin oxide film (not shown).

Then, while removing the thin oxide film by a known method, the nitride film 13 and the pad oxide film 12 are removed, although not shown.

In addition, the above method can be applied to a PBL (Poly Buffer LOCOS) method.

That is, before the formation of the nitride film 13, a buffer polysilicon film (not shown) is formed on the pad oxide film 12 to relieve stress on the nitride film 13, and then the subsequent process as described above is performed. To form a field oxide film.

According to the above embodiment, as the oxidation process is performed after the substrate is recessed, the field oxide film can be formed while minimizing the stress applied to the substrate during the oxidation process, thereby improving the characteristics and reliability of the device.

In addition, this invention is not limited to the said Example, It can variously deform and implement within the range which does not deviate from the technical summary of this invention.

Claims (5)

Sequentially forming a pad oxide film and a nitride film on the semiconductor substrate; Etching the nitride film and the pad oxide film to expose a predetermined portion of the substrate; Forming a polysilicon film on the entire surface of the substrate; First oxidizing the polysilicon film to form an oxide film on a predetermined portion of the polysilicon film; Etching the polysilicon film using the oxide film as an etching mask and recessing the substrate to a predetermined depth; And, And forming a field oxide film by second oxidation of the recessed substrate. The method of claim 1, wherein the first and second oxidation processes are performed at 900 to 1100 ° C. 3. The method of claim 2, wherein the first oxidation process is performed by a wet and dry oxidation process. 4. The method of claim 3, wherein the oxide film is formed at a grain boundary of the polysilicon film during the first oxidation process. 2. The method of claim 1, wherein a buffer polysilicon film is formed between the pad oxide film and the nitride film.