KR100281277B1 - Method for manufacturing device isolation oxide film of semiconductor device - Google Patents

Abstract

The present invention relates to a method for manufacturing a device isolation oxide film of a semiconductor device, comprising forming a nitrogen dangling bond film primarily on a semiconductor substrate and overlapping a pad oxide film and a polycrystalline silicon layer exposing a portion intended as a device isolation region; A first nitride film pattern is formed, wherein the polysilicon layer and the nitrogen dangling bond film are formed to have undercuts, and after the second nitride film pattern is applied to the surfaces of the patterns, a predetermined width is formed on the semiconductor substrates on both sides of the second nitride film pattern. After the trench was formed, the nitrogen dendling bond film was again formed on the entire surface of the exposed semiconductor substrate, and thermal oxidation was performed to form the device isolation oxide film. Thus, the second nitride film pattern prevents oxygen infiltration into the pad oxide film pattern. Prevented, this effect is further increased by the undercut, which reduces the size of the buzzvik, and nitrogen dangling bonds. This prevents oxygen penetration in the early stage of thermal oxidation, reducing the overall thickness of the device isolation oxide film, and compensating for volume expansion at the boundary of the device isolation region by trenches to prevent sudden variations in topology. Can improve the reliability.

Description

Method for manufacturing device isolation oxide film of semiconductor device

1A and 1B are manufacturing process diagrams of a device isolation oxide film of a semiconductor device according to the prior art.

2a and 2b is a manufacturing process diagram of the device isolation oxide film of the semiconductor device according to the present invention.

<Explanation of symbols for main parts of drawing>

1 semiconductor substrate 2 pad oxide film

3: polycrystalline silicon layer 4, 7: nitride film

5: device isolation oxide film 6, 10: nitrogen dangling bond film

8: thermal oxide film 9: trench

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a device isolation oxide film of a semiconductor device, and more particularly, a polybuffered LOCOS (hereinafter referred to as PBL) which performs thermal oxidation through a polysilicon layer pattern under a nitride film pattern and a pad oxide film pattern. In the process, a nitrogen dangling bond film is formed under the pad oxide film, and the polysilicon layer and the nitrogen dangling bond film are etched to have an undercut to form patterns, and then a nitride film is applied to the surfaces of the patterns, and the pad The thermal oxide film is formed by thermally oxidizing the semiconductor substrate under the nitrogen dangling bond film pattern under the oxide film pattern, and a trench having a predetermined width is formed on the semiconductor substrates on both sides of the nitride film pattern, and then nitrogen dangling on the exposed semiconductor substrate surface. Bond film is applied to prevent the side diffusion of oxygen and thermal oxidation is performed Forming an element isolation oxide film, it is advantageous in high integration of the device, and a method of manufacturing a semiconductor device process yield and device isolation oxide film which can improve the reliability of the device operation.

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.

Such a device isolation region manufacturing method is a conventional local oxidation of silicon (hereinafter referred to as LOCOS) method of thermally oxidizing a silicon semiconductor substrate using a nitride film pattern as a mask, or a separate polysilicon stacked on a semiconductor substrate. SEFOX method of thermally oxidizing the layer and trench isolation method that form trenches in semiconductor substrates and fill them with insulating materials are used. Among them, LOCOS method is widely used because of relatively simple process. There is a disadvantage that the area is large, and a buzz big is generated at the interface, so that a lattice defect is generated by the substrate stress.

The manufacturing method of the LOCOS field oxide film is as follows.

First, a surface of a semiconductor substrate made of silicon 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 an element isolation region of the semiconductor substrate. Then, the nitride film pattern is thermally oxidized. The semiconductor substrate is thermally oxidized to a predetermined thickness using a mask to form a field oxide film.

In the conventional LOCOS field oxide film, oxygen penetrates into the semiconductor substrate boundary between the active region and the field oxide film to form an inclined surface called buzz big.

Because of the stress applied to the semiconductor substrate due to the above-mentioned Buzz Big, the lattice defect is increased, the leakage current is increased, the reliability of the device operation is reduced, the area of the active area is reduced, it is difficult to high integration of the device.

In order to solve this problem, a PBL method using a polycrystalline silicon layer pattern serving as a buffer under the nitride film pattern is used.

1A and 1B are manufacturing process diagrams of a device isolation oxide film of a semiconductor device according to the prior art, which is an example of a PBL process.

First, the pad oxide film (2) pattern, the polysilicon layer (3) pattern, and the nitride film (4) pattern, which are sequentially stacked, exposing portions intended as the device isolation regions of the semiconductor substrate 1, are 150 Å and 500 Å, respectively. And a thickness of 2000 mm 3. (See also FIG. 1A).

Then, the semiconductor substrate 1 exposed by the nitride film 4 pattern is thermally oxidized to a predetermined thickness to form the device isolation oxide film 5. (See also FIG. 1B).

Here, the polysilicon layer pattern serves as a buffer layer to compensate for the oxidation of the semiconductor substrate to some extent, but the effect of reducing the size of Buzzvik is insignificant, making it difficult to achieve high integration of the device. There is a problem.

The present invention is to solve the above problems, an object of the present invention is to form a nitrogen dendling bond film on the semiconductor substrate first in the PBL process, and to form a nitride film pattern exposing the device isolation region, but the lower polycrystalline silicon The layer pattern and the nitrogen dangling bond film have undercuts, a nitride film is applied to the surfaces of the patterns, a thermal oxide film is formed again on the semiconductor substrate under the nitride film pattern, and trenches are formed on the semiconductor substrates on both sides of the nitride film pattern. A nitrogen dangling bond film is formed on the entire surface of the exposed semiconductor substrate to prevent side diffusion of oxygen, and thermal oxidation is performed to form a device isolation insulating film, thereby reducing the size of the buzz bend and miniaturization of the device isolation region. The semiconductor element can improve the process yield and the reliability of device operation by preventing stress on the semiconductor substrate. It is a method of manufacturing the element isolating oxide film to provide.

In order to achieve the above object, there is provided a method of manufacturing a device isolation oxide film of a semiconductor device according to the present invention. Forming a pad oxide film, forming a polysilicon layer on the pad oxide film, forming a first nitride film on the polysilicon layer, and overlying a portion of the semiconductor substrate that is intended as an isolation region Sequentially removing the first nitride film from the first nitride film of the first nitride film to form a first nitride film, a polycrystalline silicon layer, a pad oxide film and a first nitrogen dendling bond film pattern exposing the semiconductor substrate, wherein the polysilicon layer The pattern and the first nitrogen dangling bond film is formed to have an undercut, the first nitride film, the polycrystalline silicon layer, the pad oxide film, Forming a second nitride film pattern on the surface of the first nitrogen dangling bond film pattern to fill the undercut; reheating and oxidizing the semiconductor substrate under the first nitride film pattern to form a thermal oxide film; and the second nitride film Forming trenches in the semiconductor substrates on both sides of the pattern; forming a second nitrogen dangling bond film on the entire surface of the exposed semiconductor substrate; and thermally oxidizing the semiconductor substrate under the second nitrogen dangling bond film. To form a device isolation oxide film.

Hereinafter, a method of manufacturing a device isolation oxide film of a semiconductor device according to the present invention will be described in detail with reference to the accompanying drawings.

2A and 2B are manufacturing process diagrams of an element isolation oxide film of a semiconductor device according to the present invention.

First, a first nitrogen dangling bond film 6 having a dangling bond together with a Si-N bond is formed on the semiconductor substrate 1 made of silicon to a thickness of about 5 to 50 m 3, and about 100 to 300 m 3 above it. A thickness of the pad oxide film 2 is formed by a thermal oxidation method, and chemical vapor deposition is sequentially performed on the polycrystalline silicon layer 3 having a thickness of about 300 to 800 m 3 and the first nitride film 4 having a thickness of about 1000 to 2000 m 2 on the upper side thereof. It forms by the method (chemical vapor deposition; CVD hereafter).

Then, the first nitride film 4 and the polycrystalline crystal are sequentially removed from the first nitride film 4 on the upper portion of the semiconductor substrate 1, which is intended to be an isolation region, from the first nitrogen dendling bond film 6 to the first nitride film 4 and the polycrystalline crystal. The silicon layer 3, the pad oxide film 2, and the first nitrogen dangling bond film 6 are formed. At this time, the polysilicon layer 3 and the first nitrogen dangling bond layer 6 pattern is isotropically etched to have an undercut.

Next, a second nitride film 7 pattern is formed on a surface from the first nitrogen dangling bond film 6 pattern to the first nitride film 4 pattern to fill the undercuts, and the first nitrogen dangling bond film 6 is formed. The lower semiconductor substrate 1 is thermally oxidized again to form a thermal oxide film 8 on the semiconductor substrate 1 below the first nitrogen dangling bond film 6.

The thermal oxide film 8 prevents lattice defects caused by interfacial stress between the semiconductor substrate 1 and the second nitride film 7 pattern. In addition, the penetration of oxygen into the pad oxide film 2 pattern is prevented by the second nitride film 7 pattern, and moreover, it is formed to fill the undercuts, thereby effectively blocking oxygen.

Thereafter, a trench 9 having a predetermined width and depth is formed in the semiconductor substrate 1 on both sides of the second nitride film 7 pattern, and the thickness is about 5 to 50 mm on the entire surface of the exposed semiconductor substrate 1. The second nitrogen dangling bond film 10 is formed.

At this time, the first and second nitrogen dangling bond film (6) (10) forming process is added to the N ₂ O gas or NH ₃ gas in H ₂ + O ₂ atmosphere and thermal oxidation at a temperature of about 800 ~ 1000 ℃ In the oxide film structure, a nitrogen dangling bond film having a nitrogen dangling bond is formed.

In addition, the width of the trench 9 is formed to be as small as possible in consideration of design rules, and the depth of the trench 9 is determined within the range in which the continuity of the topology is secured in consideration of the thickness of the device isolation oxide film to be formed. (See also FIG. 2A).

Then, the device isolation oxide film 5 is formed by dry or wet thermal oxidation of the semiconductor substrate 1 under the second nitrogen dangling bond layer 10 at a predetermined temperature, for example, at a temperature of about 800 to 1200 ° C. At this time, the second nitride film 7 pattern prevents oxygen from penetrating into the pad oxide film 2 pattern, thereby reducing the size of the buzz beak, and initially the semiconductor substrate 1 by the second nitrogen dangling bond film 10. Since oxygen penetrates after a certain period of time to prevent oxygen from penetrating into the oxygen), the thickness of the device isolation oxide film 5 is reduced, and the volume expansion to the upper side is also reduced by the trench 9. . (See also figure 2b).

As described above, the method of manufacturing a device isolation oxide film of a semiconductor device according to the present invention includes forming a nitrogen dangling bond film on a semiconductor substrate and exposing an overlapped pad oxide film to expose a portion intended as a device isolation region. A polysilicon layer and a first nitride film pattern are formed, wherein the polysilicon layer and the nitrogen dangling bond film are formed to have undercuts, and after the second nitride film pattern is applied to the surfaces of the patterns, semiconductors on both sides of the second nitride film pattern are formed. A trench having a predetermined width was formed on the substrate, and a nitrogen dangling bond film was formed on the entire surface of the exposed semiconductor substrate, and then thermally oxidized to form an element isolation oxide film. Thus, the second nitride film pattern was used as a pad oxide film pattern. Oxygen penetration is prevented, and this effect is further increased by undercuts, which reduces the size of the buzz The oxygen densification is prevented at the beginning of thermal oxidation by the nitrogen dangling bond film, and the overall thickness of the device isolation oxide film is reduced, and the trench compensates for the volume expansion at the boundary of the device isolation region. Since it is prevented there is an advantage that can improve the process yield and the reliability of device operation.

Claims (11)

Forming a first nitrogen dangling bond film on the semiconductor substrate, forming a pad oxide film on the nitrogen dangling bond film, forming a polysilicon layer on the pad oxide film, and forming a polysilicon layer on the pad Forming a first nitride film on the semiconductor substrate; and sequentially removing the first nitride film from the first nitride film on the upper portion of the semiconductor substrate to the first nitrogen dangling bond film to expose the semiconductor substrate. Forming a polysilicon layer, a pad oxide film, and a first nitrogen dangling bond film pattern, wherein the polysilicon layer pattern and the first nitrogen dangling bond film are formed to have an undercut; and the first nitride film, the polycrystalline silicon layer, and a pad Forming a second nitride film pattern on a surface of an oxide film and a first nitrogen dangling bond film pattern to fill the undercut; Reforming the semiconductor substrate under the nitride film pattern to form a thermal oxide film; forming a trench in the semiconductor substrate on both sides of the second nitride film pattern; and second nitrogen dangling on the entire surface of the exposed semiconductor substrate. And forming a device isolation oxide film by thermally oxidizing the semiconductor substrate under the second nitrogen dangling bond film, thereby forming a device isolation oxide film. The method of claim 1, wherein the first and second nitrogen dangling bond films are formed to a thickness of about 5 to 30 μm. The device isolation oxide film of claim 1, wherein the first and second nitrogen dangling bond film forming processes are formed by adding N ₂ O gas or NH ₃ gas in an H ₂ + O ₂ atmosphere. Manufacturing method. 2. The method of claim 1, wherein the nitrogen dangling bond film forming process is thermally oxidized at a temperature of 800 ° C. to 1000 ° C. 3. 2. The method of claim 1, wherein the pad oxide film is formed to a thickness of 100 to 300 kHz. The method of claim 1, wherein the polysilicon layer is formed to a thickness of 300 to 800 Å. The method of claim 1, wherein the first nitride film is formed to a thickness of 1000 to 2000 GPa. The method of claim 1, wherein the trench is formed according to a design rule of a device process. 2. The method of claim 1, wherein the thermal oxide film is formed to a thickness of 10 to 30 [mu] s. The method of claim 1, wherein the thermal oxidation process for forming the device isolation oxide film is performed at a temperature of 900 to 1200 ° C. 9. The method of claim 1, wherein the thermal oxidation process for forming the device isolation oxide film is performed by a dry or wet method.