KR19990042453A - Device Separation Method of Semiconductor Device - Google Patents

Abstract

The present invention relates to a method for manufacturing a device isolation film of a semiconductor device, and after forming a trench, performing a thermal oxide film formation and removal process for removing defects in the trench surface generated during the trench formation process, and then again forming a thermal oxide film on the trench surface. When the thermal oxide film is first heat-treated in a low temperature N2O atmosphere, nitrogen atoms penetrate into the thermal oxide film and the semiconductor substrate interface to prevent the interface from warping, and the weak oxide part is reinforced to reinforce the thermal oxide film and the semiconductor substrate. To reduce the interface trap charge caused by dangling bonds of Si and O at the interface, to reduce the compressive stress generated during the oxidation process to improve the electrical properties of the thermal oxide film, Fixed charge in the thermal oxide film by performing a second heat treatment process in a high temperature N2 atmosphere Reduced by an electrical to obtain a stable trench surface and a thermal oxide film technology to improve the reliability and characteristics of the semiconductor device thereof.

Description

Device Separation Method of Semiconductor Device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a device isolation film of a semiconductor device. In particular, in the process of forming a device isolation film by filling a trench with an insulator, the insulating material filling the trench is subjected to a first heat treatment at a low temperature to reduce the nitride film and the etching selectivity. Next, by removing the nitride film, the residue generated during the formation of the gate electrode is prevented from remaining, and the second heat treatment process is performed again at a high temperature to prevent the loss of the insulating material filling the trench during the subsequent cleaning process. It is to provide a device isolation film manufacturing method of a semiconductor device to improve the electrical characteristics.

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 (hereinafter referred to as 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, a surface of the semiconductor substrate is thermally oxidized to form a pad oxide film, and a nitride film pattern is formed on the pad oxide film to expose a predetermined portion to the device isolation region of the semiconductor substrate. Then, the nitride film pattern is a thermal oxidation mask. The substrate is thermally oxidized to a predetermined thickness to form a field oxide film.

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, the lattice defects are increased, the leakage current is increased, the reliability of the device operation is deteriorated, and the area of the active area is reduced, making the device highly integrated.

In order to prevent the area of the active region from being reduced as described above, a device isolation film manufacturing method using a trench capable of separating devices into small areas is widely used in ultra-high integration devices.

Although not illustrated, a method of manufacturing a device isolation film of a semiconductor device according to the related art will be described below.

First, a first insulating film is formed on the semiconductor substrate using a thermal oxide film, and a second insulating film is formed on the semiconductor substrate.

Next, a first photoresist layer pattern is formed on the second insulation layer to expose a portion of the device isolation region, and the first photoresist layer pattern is etched using the second insulation layer, the first insulation layer, and the semiconductor substrate having a predetermined thickness. Etch to form a trench.

Next, the thermal oxide film is grown on the sidewalls of the trench and then removed to remove defects on the trench surface, and the thermal oxide film is grown again.

A third insulating film which completely fills the trench on the entire surface of the structure is formed by chemical vapor deposition (hereinafter referred to as CVD), and then the third insulating film is chemically mechanically polished. The CMP is then polished until the second insulating film is exposed.

Next, the second insulating film and the first insulating film are removed, a gate oxide film is formed, and a gate electrode having a polysilicon layer pattern is formed.

In the method of manufacturing a device isolation film of a semiconductor device according to the related art as described above, a thermal oxide film generated when a thermal oxide film is formed on the sidewalls of the trench can be reduced, although the interface capture charge at the trench and the insulating film interface filling the trench can be reduced. It is difficult to prevent the interfacial capture charge and the fixed charge in the thermal oxide film from occurring at the trench trench region. In addition, the interface capture charges formed as described above have a problem of protecting or releasing charges of electrons or holes, thereby deteriorating the electrical characteristics of the trench surface and the thermal oxide interface and the thermal oxide film.

In order to solve the above problems, the present invention provides a thermal oxide film on the surface of the trench after forming a trench in a device isolation process using a trench, and heat treating the thermal oxide film in a N 2 O and N 2 atmosphere for 2 times. It is an object of the present invention to provide a method for manufacturing a device isolation film of a semiconductor device by forming an electrically stable oxide film on the sidewall of the trench to improve the electrical characteristics of the device isolation film.

1 to 6 are cross-sectional views showing a device isolation film manufacturing method of a semiconductor device according to the present invention.

<Description of Symbols for Main Parts of Drawings>

11: semiconductor substrate 13: first insulating film

15: second insulating film 17: trench

19: second thermal oxide film 21: third insulating film

In order to achieve the above object, a device isolation film manufacturing method of a semiconductor device according to the present invention,

Sequentially forming an oxide film and a nitride film on the semiconductor substrate;

Forming a trench by etching the oxide film, the nitride film, and the semiconductor substrate by an etching process using an isolation mask;

Removing defects on the trench surface;

Forming a thermal oxide film on the trench surface;

First heat treating the thermal oxide film in an N 2 O atmosphere;

Performing a second heat treatment on the thermal oxide film in an N 2 atmosphere;

And forming an insulating film filling the trench.

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

1 to 6 are cross-sectional views illustrating a method of manufacturing a device isolation film of a semiconductor device according to the present invention. In particular, FIGS. 5A and 5B show an interface between a second thermal oxide film and a semiconductor substrate.

First, the first insulating layer 13 is formed on the semiconductor substrate 11. At this time, the first insulating film 13 is a thermal oxide film, and is formed to have a thickness of 50 to 200 GPa.

A nitride film, which is the second insulating film 15, is deposited on the first insulating film 13 to a thickness of 1000 to 3000 GPa. (See Fig. 1)

In addition, a first photoresist pattern (not shown) is formed on the second insulating layer 15 to expose a portion of the device isolation region, and then the second insulating layer 15 and the first insulating layer 13 and a predetermined portion are exposed. The semiconductor substrate 11 having a thickness is etched to form a trench 17, and the first photoresist pattern is removed. At this time, the semiconductor substrate 11 is etched 1500 ~ 4000 mm deep. (See Fig. 2)

Thereafter, a first thermal oxide film (not shown) is formed on the surface of the trench 17 by a thickness of 50 to 200 Å and then removed by a wet etching process to damage the semiconductor substrate during the etching process to form the trench 17 ( This is to remove the defect on the surface of 11). At this time, the first thermal oxide film is over-etched by a dry or wet method to a thickness of 100 ~ 300 kPa. (See Fig. 3)

Next, a second thermal oxide film 19 having a thickness of about 50 to about 200 kPa is grown on the sidewall of the trench 17 again. In this case, the second thermal oxide film 19 is to reduce the interface capture charge at the interface between the third insulating film 21 and the semiconductor substrate 11. (See Fig. 4)

FIG. 5A is a view illustrating an interface state between the second thermal oxide film 19 and the semiconductor substrate 11 after the second thermal oxide film 19 is formed.

Next, the second thermal oxide film 19 is subjected to a first heat treatment process in an N 2 O atmosphere at a temperature of 500 to 1000 ° C.

In this case, the first heat treatment process reduces the interface capture charge by the dangling bond between Si and O at the interface between the second thermal oxide film 19 and the semiconductor substrate 11, and compressive stress generated during the subsequent oxidation process. Also decrease. In addition, nitrogen atoms penetrate into the interface to prevent the interface from bending.

Next, the second thermal oxide film 19 is subjected to a secondary heat treatment step in an N 2 atmosphere at a temperature of 1000 to 1500 ° C. In this case, the secondary heat treatment process reduces the fixed charge in the second thermal oxide film 19. (See Fig. 5b)

Next, the third insulating layer 21 is formed to fill the trench 17 and cover the second insulating layer 15. At this time, the third insulating film 21 is formed to a thickness of 3000 ~ 8000 Å. (See FIG. 6)

As described above, in the method of fabricating an isolation layer of a semiconductor device according to the present invention, the trench surface is formed, and then a thermal oxide film formation and removal process for removing defects in the trench surface generated during the trench formation process is performed. When a thermal oxide film is formed on the thermal oxide film and the thermally oxidized film is first heat-treated in a low temperature N 2 O atmosphere, nitrogen atoms penetrate into the thermal oxide film and the semiconductor substrate interface to prevent the interface from warping, and the weak oxide part is reinforced to reinforce the thermal oxide film Reduces interfacial capture charges caused by dangling bonds between Si and O at the interface of semiconductor and semiconductor substrates, and reduces the compressive stress generated during the oxidation process to improve the electrical properties of the thermal oxide film. By performing a differential heat treatment process to reduce the fixed charge in the thermal oxide film, And the gain set by the trench surface and a thermal oxide film, there is the advantage of improving the reliability and the characteristics of the semiconductor device thereof.

Claims (7)

Sequentially forming an oxide film and a nitride film on the semiconductor substrate; Forming a trench by etching the oxide film, the nitride film, and the semiconductor substrate by an etching process using an isolation mask; Removing defects on the trench surface; Forming a thermal oxide film on the trench surface; First heat treating the thermal oxide film; Performing a second heat treatment of the thermal oxide film; And forming an insulating film filling the trench. The method of claim 1, The trench is a device isolation film manufacturing method of a semiconductor device, characterized in that formed by etching the semiconductor substrate of 1500 ~ 4000 4000 depth. The method of claim 1, The method of removing a defect on the trench surface is performed by forming a thermal oxide film having a thickness of 50 to 200 Å on the trench surface and removing the thermal oxide film. The method of claim 3, wherein The thermal oxide film removing process is a device isolation film manufacturing method of a semiconductor device, characterized in that the wet or dry etching process. The method of claim 1, The thermal oxide film is a device isolation film manufacturing method of a semiconductor device, characterized in that formed in 50 ~ 200Å thickness. The method of claim 1, The first heat treatment process is a device isolation film manufacturing method of a semiconductor device, characterized in that carried out in an N 2 O atmosphere of 500 ~ 1000 ℃ temperature. The method of claim 1, The secondary heat treatment process is a device isolation film manufacturing method of a semiconductor device, characterized in that carried out in an N2 atmosphere of 1000 ~ 1500 ℃ temperature.