KR100245087B1 - Device isolation insulating film formation method of semiconductor device - Google Patents

Abstract

The present invention relates to a method for forming a device isolation insulating film of a semiconductor device, comprising: forming a device isolation insulating film having a flattened upper surface by a changed LOCOS method, wherein a first insulating film and a second insulating film are formed on the semiconductor substrate, and the second insulating film is formed on the semiconductor substrate. The second insulating film and the first insulating film are etched to expose the semiconductor substrate in the isolation region, and then a third insulating film spacer is formed on sidewalls of the second insulating film and the first insulating film, and the semiconductor is formed using the second and third insulating films as masks. After etching the substrate to a certain depth to form a groove, the semiconductor substrate is thermally oxidized to form a fourth insulating film, the second and third insulating films are removed, a fifth insulating film is formed on the semiconductor substrate, and the fifth insulating film is formed. And the first insulating film is removed to form a device isolation insulating film having a flat top surface, thereby facilitating subsequent processes and To reduce the set current is improve the characteristics and reliability of the semiconductor device and technique that enables high integration of the semiconductor device thereof.

Description

Device isolation insulating film formation method of semiconductor device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a device isolation insulating film of a semiconductor device, and more particularly, to a technique of preventing damage to a device isolation insulating film filling a trench and improving characteristics and reliability of the semiconductor device.

In order to increase the integration of devices in terms of high integration, it is necessary to reduce each device dimension and to reduce the width and area of isolation regions existing between devices. In terms of size, the device isolation technology is a technology for determining the memory cell size.

Conventional methods for manufacturing device isolation insulating films include LOCOS (LOCOS: LOCOS) method, an oxide film, a polysilicon layer, and a nitride film stacked on top of a silicon substrate. B.L. (Poly-Buffed LOCOS, hereinafter referred to as PBL), a trench method in which a groove is formed in a substrate and then filled with an insulating material.

However, a process or electrical problem occurs when the device isolation oxide film is miniaturized by the LOCOS method. One of them is that the device isolation insulating film alone cannot completely separate the devices.

Therefore, a high concentration of B or BF ₂ ions are implanted into the lower portion of the device isolation insulating film immediately before or after the oxidation process to form the device isolation oxide film, thereby compensating the isolation effect. It is called an implant process, that is, a channel stopper forming process.

In addition, the LOCOS method forms a high step on top of the semiconductor substrate, making subsequent processing difficult.

1A and 1C are cross-sectional views illustrating a method of forming a device isolation insulating film of a semiconductor device according to the prior art.

First, a pad oxide film 33 is formed on the semiconductor substrate 31, and a first nitride film 35 is formed on the pad oxide film 33.

In addition, the first nitride layer 35 and the pad oxide layer 33 are etched by an etching process using an element isolation mask (not shown) (FIG. 1A).

Next, a spacer of the second nitride film 37 is formed on sidewalls of the first nitride film 35 and the pad oxide film 33. In this case, the second nitride film 37 spacers are formed by forming a predetermined thickness on the entire surface of the second nitride film 37 and anisotropically etching them.

The exposed semiconductor substrate 31 is thermally oxidized to form a thermally oxidized film 39. In this case, the second nitride layer 37 spacer is used as a barrier during the growth process of the thermal oxide layer 39. (FIG. 1B)

Then, the second nitride film 37 spacer, the first nitride film 35 and the pad oxide film 33 are removed by a wet method. In this case, a device isolation insulating layer 41 is formed by etching a portion of the upper portion of the thermal oxide layer 39.

The surface of the semiconductor substrate 31 is thermally oxidized to form a gate oxide film 43.

Here, ⓐ shows a jaw phenomenon that is formed by the stress between the nitride film and the oxide film generated during the thermal oxidation process of forming the oxide film 39 and is inclined from the device isolation region to the active region. 1c)

As described above, the method of forming a device isolation insulating film of a semiconductor device according to the prior art makes it difficult to follow-up processes due to the jaw phenomenon and causes leakage current of the semiconductor substrate, thereby degrading the characteristics and reliability of the semiconductor device and thereby the semiconductor device. There is a problem that makes it difficult to integrate.

Therefore, in order to solve the above problems of the prior art of the present invention, by forming a device isolation insulating film compensated for the jaw phenomenon by the changed LOCOS method to facilitate the subsequent process and to suppress the leakage current of the semiconductor substrate and It is an object of the present invention to provide a method for forming a device isolation insulating film of a semiconductor device that improves reliability and thereby enables high integration of the semiconductor device.

1A to 1C are cross-sectional views illustrating a method of forming a device isolation insulating film of a semiconductor device according to the prior art.

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

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

11,31: semiconductor substrate 13,33: pad oxide film

15,35: first nitride film 17,37: second nitride film

19: groove 21: first thermal oxide film

23 amorphous silicon film 25 second thermal oxide film

27,43 gate oxide film 29,41 device isolation insulating film

39: thermal oxide filmⓐ: the part showing the jaw phenomenon

In order to achieve the above object, a method of forming a device isolation insulating film of a semiconductor device according to the present invention is a method of forming a device isolation insulating film having a planarized upper surface by a changed LOCOS method, wherein a first insulating film and a second insulating film are formed on an upper portion of the semiconductor substrate. Forming a predetermined thickness, exposing the semiconductor substrate in the device isolation region by etching the second insulating film and the first insulating film, and forming a second insulating film spacer on the sidewalls of the second insulating film and the first insulating film. Forming a groove by etching the semiconductor substrate with a predetermined depth using the second and third insulating films as a mask, forming a fourth insulating film by thermally oxidizing the semiconductor substrate, and forming the second and third insulating films A step of forming a fifth insulating film on the semiconductor substrate, and a step of removing the fifth insulating film and the first insulating film. And it characterized in that.

On the other hand, the principle of the present invention for achieving the above object is, by growing a thermal oxide film in the device isolation region, removing the nitride film, depositing amorphous silicon on the entire surface and oxidizing all the amorphous silicon to form an oxide film By removing the oxide film and the pad oxide film and forming a gate oxide film, the jaw phenomenon is not induced. Instead of forming the amorphous silicon film, the CVD oxide film may be deposited on the entire surface of the substrate.

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

2A to 2F are cross-sectional views illustrating a method of forming a device isolation insulating film of a semiconductor device according to an embodiment of the present invention.

First, the pad oxide film 13 and the first nitride film 15 are formed to have a predetermined thickness on the semiconductor substrate 11, respectively. In addition, the first nitride layer 15 and the pad oxide layer 13 are etched by an etching process using an element isolation mask (not shown).

Here, the pad oxide film 13 is formed to a thickness of about 50 to 300 kPa, and the first nitride film 15 is formed to a thickness of about 1500 to 3000 kPa. (FIG. 2A)

Next, a second nitride film spacer 17 is formed on the sidewalls of the first nitride film 15 and the pad oxide film 13. At this time, the second nitride film 17 spacer is formed on the entire surface by forming a thickness of the second nitride film 17 of about 50 ~ 500Å and anisotropically etched it.

The groove 19 is formed by etching the semiconductor substrate 11 in a depth of about 50 to 500 mV using the first nitride film 15 and the second nitride film 17 as a mask. (FIG. 2B)

Thereafter, the semiconductor substrate 11 is thermally oxidized to form a first thermal oxide film 21 in an area in which the semiconductor substrate 11 is exposed and in an isolation region. In this case, the second nitride film 17 spacer Is used as a barrier during the growth process of the first thermal oxide film 21.

Here, the thermal oxidation process is carried out at a temperature of about 900 ~ 1200 ℃, the first thermal oxide film 21 is formed to a thickness of about 2000 ~ 4000Å. (FIG. 2C)

Next, the spacers of the first nitride film 15 and the second nitride film 17 are removed using a phosphoric acid solution.

Then, an amorphous silicon film 23 is deposited on the entire surface with a thickness of about 100 to 500 mW. At this time, the deposition process of the amorphous silicon film 23 is performed at a temperature of about 500 ~ 700 ℃. (FIG. 2D)

Next, the amorphous silicon film 23 is oxidized and thermally oxidized to form a second thermal oxide film 25. In this case, the thermal oxidation process is performed at a temperature of about 800 to 1100 ° C., and a part of the semiconductor substrate 11 is also oxidized. (FIG. 2E)

Next, the second thermal oxide film 25 and the pad oxide film 13 are removed with a hydrofluoric acid solution to form a device isolation insulating film 29, and the gate oxide film 27 is formed on the semiconductor substrate 11. A device isolation insulating film 29 is removed from which the phenomenon is removed (FIG. 2F).

As described above, in the method of forming a device isolation insulating film of the semiconductor device according to the present invention, the first thermal oxide film is formed by the changed LOCOS method, the nitride film is removed, an amorphous silicon film is formed on the entire surface, and the second silicon oxide film is thermally oxidized. After the thermal oxide film is formed, the second thermal oxide film and the pad oxide film are removed, and a gate oxide film is formed to form a device isolation insulating film having a flat top surface, thereby improving the characteristics and reproducibility of the semiconductor device and consequently high integration of the semiconductor device. Has the effect of enabling.

Claims (12)

In the method of forming a device isolation insulating film having a flattened top surface by a changed LOCOS method, Forming a first thickness of the first insulating film and a second insulating film on the semiconductor substrate, respectively; Etching the second insulating film and the first insulating film to expose a semiconductor substrate in an isolation region; Forming a second insulating film spacer on sidewalls of the second insulating film and the first insulating film; Forming a groove by etching the semiconductor substrate with a predetermined depth using the second and third insulating films as a mask; Thermally oxidizing the semiconductor substrate to form a first insulating film; Removing the second and third insulating films; Forming a fifth insulating film on the semiconductor substrate; And removing the fifth insulating film and the first insulating film. The method according to claim 1, The first insulating film is a method of forming a device isolation insulating film of a semiconductor device, characterized in that for forming a pad oxide film having a thickness of about 50 ~ 300Å. The method according to claim 1, The second insulating film is a method of forming a device isolation insulating film of a semiconductor device, characterized in that to form a nitride film having a thickness of about 1500 ~ 3000Å. The method according to claim 1, The third insulating film is a method of forming a device isolation insulating film of a semiconductor device, characterized in that for forming a nitride film having a thickness of about 50 ~ 500Å. The method according to claim 1, The groove is a method of forming a device isolation insulating film of a semiconductor device, characterized in that formed in a thickness of about 50 ~ 500Å. The method according to claim 1, The fourth insulating film is a method of forming a device isolation insulating film of a semiconductor device, characterized in that formed by thermal oxidation at a temperature of about 900 ~ 1200 ℃. The method according to claim 6, The fourth insulating film is a method of forming a device isolation insulating film of a semiconductor device, characterized in that formed in a thickness of about 2000 ~ 400Å. The method according to claim 1, And a portion of the upper side of the fourth insulating layer is removed during the second and third insulating layer removing processes. The method according to claim 1, And the fifth insulating film is formed by forming an amorphous silicon film on the entire surface and thermally oxidizing it. The method according to claim 9, The amorphous silicon film is a method of forming a device isolation insulating film of a semiconductor device, characterized in that formed at a temperature of about 500 ~ 700 ℃. The method according to claim 1 or 9, Wherein the amorphous silicon film is formed to a thickness of about 100 ~ 500 반도체. The method according to claim 1, And the fifth insulating film and the first insulating film are removed using a hydrofluoric acid solution.