KR101026478B1 - Method for forming isolation of semiconductor device - Google Patents

Abstract

The present invention relates to a method of forming a device isolation film of a semiconductor device capable of preventing the occurrence of defects due to the limitation of trench filling with an increase in the aspect ratio. The present invention comprises the steps of depositing a pad oxide film and a pad nitride film on a semiconductor substrate; Etching the pad nitride layer, the pad oxide layer, and the substrate to form a first trench; Forming a sacrificial oxide spacer on a sidewall of the first trench; Etching the substrate under the first trench using the sacrificial oxide spacer as a mask to form a second trench having a width smaller than that of the first trench under the first trench; Filling an insulating film in the second trench; Removing the sacrificial oxide spacers; Forming a sidewall oxide film on the surface of the first trench; Depositing a liner nitride film on the entire surface including the sidewall oxide film; Depositing a buried insulating film on the entire surface including the first trench so that the first trench is buried; CMPing the buried insulating film and the liner nitride film to expose the pad nitride film; And removing the pad nitride film.

Description

Method for forming isolation of semiconductor device

1 to 5 are cross-sectional views illustrating a method of forming a device isolation film of a semiconductor device in accordance with an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: substrate 11: pad oxide film

12: pad nitride film 13: first trench

14: LP TEOS oxide film 15: second trench

16: nitride film 17: sidewall oxide film

18: liner nitride film 19: HDP oxide film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method of forming a device isolation film of a semiconductor device capable of preventing defects caused by limitation of trench filling due to an increase in aspect ratio.

With the progress of semiconductor technology, the speed and the high integration of semiconductor devices are progressing rapidly, and with this, the demand for the refinement | miniaturization of a pattern and the high precision of a pattern dimension is increasing. This requirement applies not only to patterns formed in device regions, but also to device isolation films that occupy a relatively large area.

Here, a conventional device isolation film has been formed by a locos process. As is well known, the device isolation film by the locos process generates a bird's beak having a beak shape at an edge thereof. Therefore, there is a disadvantage in that the area of the device isolation layer is increased.

Accordingly, a method of forming a device isolation film using a shallow trench isolation (STI) process has been proposed in place of the LOCOS process. Currently, most semiconductor devices form a device isolation film by applying an STI process. According to the device isolation film forming method using the STI process, the device isolation film has excellent device isolation characteristics while having a small width.

A device isolation film forming method using the STI process will be briefly described as follows.

First, in a state in which a pad oxide film and a pad nitride film are sequentially formed on a semiconductor substrate, the films are patterned to expose a substrate region corresponding to an isolation region, and subsequently, the exposed substrate region is etched to form a trench.

Then, an insulating film is deposited on the entire area of the substrate by the high density plasma-chemical vapor deposition (HDP-CVD) method so that the trench is buried, and the surface of the insulating film is chemical mechanical polishing (CMP) until the nitride film is exposed. After that, the pad nitride layer and the pad oxide layer are removed to form a trench type isolation layer.

However, according to the method of forming a device isolation film using the conventional STI process as described above, the trench is buried by the HDP-CVD method which has excellent buried characteristics, but the trench width is further reduced by high integration. In the trend that the aspect ratio is increasing, there is a limit to the trench filling of the fine width of the insulating film by the HDP-CVD method.

In other words, in the STI process with small aspect ratio, it is not difficult to fill the trench by the HDP-CVD method, but the linear nitride film is applied to improve the refresh characteristics. There is a difficulty in filling the trench perfectly.

As a result, the device isolation film according to the STI process loses its function due to voids in the subsequent etching and cleaning processes, and thus, the device characteristics are deteriorated.

Accordingly, the present invention has been made to solve the problems of the prior art as described above, an object of the present invention is to provide a device of a semiconductor device capable of preventing the occurrence of defects due to the limitation of trench filling due to the increase in the aspect ratio Its purpose is to provide a method of forming a separator.

In order to achieve the above object, the present invention comprises the steps of depositing a pad oxide film and a pad nitride film on a semiconductor substrate; Etching the pad nitride layer, the pad oxide layer, and the substrate to form a first trench; Forming a sacrificial oxide spacer on a sidewall of the first trench; Etching the substrate under the first trench using the sacrificial oxide spacer as a mask to form a second trench having a width smaller than that of the first trench under the first trench; Filling an insulating film in the second trench; Removing the sacrificial oxide spacers; Forming a sidewall oxide film on the surface of the first trench; Depositing a liner nitride film on the entire surface including the sidewall oxide film; Depositing a buried insulating film on the entire surface including the first trench so that the first trench is buried; CMPing the buried insulating film and the liner nitride film to expose the pad nitride film; And removing the exposed pad nitride film.

The first trench is formed to a depth of 500 ~ 1500Å.

The sacrificial oxide spacer is formed of an LP TEOS oxide layer.

The second trench is formed to a width of 100 ~ 200Å and a depth of 500 ~ 1500Å.

The step of embedding the insulating layer in the second trench may include partially wet etching the sacrificial oxide spacers; Depositing a nitride film on the substrate including the second trench to fill the second trench; And removing the nitride film formed on the outside of the second trench.

The buried insulating film is formed of an HDP oxide film.

(Example)

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

1 to 5 are cross-sectional views illustrating a method of forming an isolation layer of a semiconductor device in accordance with an embodiment of the present invention.

Referring to FIG. 1, the pad oxide film 11 and the pad nitride film 12 are deposited on the semiconductor substrate 10, and then the pad nitride film 12 is patterned to expose the pad oxide film 11 in the device isolation region. . Subsequently, the pad oxide film 11 and the substrate 10 are etched using the pad nitride film 12 as a mask to form a first trench 13 having a depth of 1500 Å or less, preferably 500 to 1500 Å.

Referring to FIG. 2, the LP TEOS oxide layer 14 is deposited on the entire surface including the first trench 13. The deposition of the LP-TEOS oxide film 14 is performed such that a distance of approximately 200 μs exists between the LP TEOS oxide film 14 in the first trench 13.
Referring to FIG. 3, the LP TEOS oxide layer 14 is etched to form spacers 14a on the sidewalls of the first trenches 13, and the spacers 14a are masked under the first trenches 13. The substrate 10 is etched to form a second trench 15 having a width smaller than that of the first trench 13 under the first trench 13. The second trench 15 is formed to a width of 200 kPa or less and a depth of 1500 kPa or less. Preferably, the second trench 15 is formed to a width of 100 to 200 kPa and a depth of 500 to 1500 kPa.

Then, the spacer 14a is partially wet-etched to secure a space in the first trench 13, and the nitride film 16 is disposed on the entire surface including the second trench 15 so that the second trench 15 is embedded. Deposit.

Referring to FIG. 4, after removing the nitride film 16 formed outside the second trench 15, the spacer 14a is removed, and the sidewall oxide film 17 is 80 μm thick on the surface of the first trench 13. Form. Subsequently, a liner nitride film 18 is deposited to a thickness of 50 kHz on the entire surface including the sidewall oxide film 17. Then, the HDP oxide film 19 is deposited on the entire surface including the first trench 13 so that the first trench 13 is buried. Here, since the first trench 13 is formed to be shallower than the desired device isolation film depth and has an aspect ratio that can be embedded in the HDP-CVD oxide film, the buried characteristic is not generated when the first trench 13 is embedded in the HDP oxide film. Can be improved.

Referring to FIG. 5, the device isolation layer is formed by CMPing the HDP oxide layer 19 and the liner nitride layer 18 so that the pad nitride layer 12 is exposed. Thereafter, although not shown, the pad nitride film 12 is removed and a semiconductor device is manufactured through the device manufacturing process.

While the present invention has been illustrated and described with reference to certain preferred embodiments, the invention is not limited thereto, and the invention is not limited to the spirit or field of the invention as defined by the following claims. It will be readily apparent to one of ordinary skill in the art that various modifications and variations can be made.

As described above, according to the present invention, by dividing the trench into two trenches, the first trench is formed to have a small aspect ratio, and the second trench is formed below the first trench, thereby preventing the generation of voids when the trench is buried. Therefore, not only the reliability of the device isolation film can be improved but also the device characteristics can be improved.

Claims (6)

Depositing a pad oxide film and a pad nitride film on the semiconductor substrate; Etching the pad nitride layer, the pad oxide layer, and the substrate to form a first trench; Forming a sacrificial oxide spacer on a sidewall of the first trench; Etching the substrate under the first trench using the sacrificial oxide spacer as a mask to form a second trench having a width smaller than that of the first trench under the first trench; Filling an insulating film in the second trench; Removing the sacrificial oxide spacers; Forming a sidewall oxide film on the surface of the first trench; Depositing a liner nitride film on the entire surface including the sidewall oxide film; Depositing a buried insulating film on the entire surface including the first trench so that the first trench is buried; CMPing the buried insulating film and the liner nitride film to expose the pad nitride film; And Removing the pad nitride film; and forming a device isolation film for the semiconductor device. The method of claim 1, Wherein the first trench is formed to a depth of 500 to 1500 Å. The method of claim 1, And the sacrificial oxide spacer is formed of an LP TEOS oxide film. The method of claim 1, And the second trench is formed to a width of 100 to 200 및 and a depth of 500 to 1500 Å. The method of claim 1, The filling of the insulating layer in the second trench may include partially wet etching the sacrificial oxide spacer; Depositing a nitride film on the entire surface including the second trench to fill the second trench; And removing the nitride film formed on the outside of the second trench. The method of claim 1, And the buried insulating film is formed of an HDP oxide film.

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