KR19990055791A - Device Separation Method of Semiconductor Device - Google Patents

Abstract

The present invention relates to a method of manufacturing a device isolation film of a semiconductor device, by forming a thin nitride film as a chemical mechanical polishing prevention layer and a chemical vapor deposition oxide film formed on the upper portion, the mask process can be carried out more easily than the mask process proceeds on the nitride film After the chemical mechanical polishing process is performed to reveal the chemical vapor deposition oxide film, the chemical vapor deposition oxide film on the upper part of the nitride film removal process has a faster wet etching rate than the insulating material filling the trench. It is possible to reduce the wet etching time, thereby reducing the amount of etching of the buried insulator, thereby preventing the buried insulator from being formed below the active region of the semiconductor substrate.

Description

Device Separation Method of Semiconductor Device

The present invention relates to a method for manufacturing a device isolation film of a semiconductor device, and in particular, when forming a device isolation film using a trench, the thickness of the nitride film is lowered, and the mask process is performed using a chemical vapor deposition oxide film having an etching rate faster than that of an insulating material filling the trench. The present invention relates to a technique for easily proceeding and reducing the etching time to reduce the insulating material filling the trench to be formed lower than the active region of the semiconductor substrate.

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 may be used.

Hereinafter, a device isolation film manufacturing method of a semiconductor device according to the prior art will be described with reference to the accompanying drawings.

1A and 1B are cross-sectional views illustrating a method of manufacturing a device isolation film of a semiconductor device in accordance with a first embodiment of the prior art, and FIGS. 2A and 2B illustrate a device isolation film of a semiconductor device in accordance with a second embodiment in the prior art. It is a cross-sectional view showing the method.

First, a pad oxide film 102 is deposited on the semiconductor substrate 101, and a nitride film 103 is deposited on the pad oxide film 102.

Next, a trench (not shown) is formed by removing the nitride film 103, the pad oxide film 102, and the semiconductor substrate 101 of the portion intended as the device isolation region.

Next, a first thermal oxide layer (not shown) is formed on the etching surface of the trench to remove defects occurring in the etching surface of the trench in the process of forming the trench, and then removed by a wet etching method.

Next, a second thermal oxide film (not shown) is formed on the etching surface of the trench, and a buried insulator 105 filling the trench is formed. In this case, the buried insulator 105 is formed to cover the nitride film 103.

Next, the buried insulator 105 is removed by a chemical mechanical polishing (CMP) method, and a wet etching method is used to remove the buried insulator 105 remaining on the nitride film 103. Carry out an etching process.

Next, the nitride layer 103 and the pad oxide layer 102 are removed to form an isolation layer using a trench.

However, in the method of manufacturing a device isolation film of a semiconductor device according to the prior art as described above, when the insulating film is embedded in the trench and the insulating material remaining on the nitride film is removed by a wet etching method, the thickness of the nitride film is low. The insulating film may be formed lower than the height of the semiconductor substrate (see FIGS. 1A and 1B), and when the nitride film is formed thick, the trench is deep and it is very difficult to fill the trench (see FIGS. 2A and 2B). ), When the polysilicon layer is formed on the nitride film, there is a problem of leaving a residue (polymer) at the edge of the insulator during the etching process.

The present invention to solve the above problems of the prior art, to form a low nitride film thickness, forming a chemical vapor deposition oxide film having a faster etching rate than the insulating material filling the trench on top of the process of the mask process on the nitride film It is an object of the present invention to provide a method of manufacturing a device isolation film of a semiconductor device, which makes it possible to proceed more easily and prevents an insulator filled with a trench from being lower than a semiconductor substrate by reducing an etching time.

1A and 1B are cross-sectional views illustrating a method of manufacturing a device isolation film of a semiconductor device according to a first embodiment of the prior art;

2A and 2B are cross-sectional views illustrating a method of manufacturing a device isolation film of a semiconductor device in accordance with a second embodiment of the prior art;

3A to 3I are cross-sectional views illustrating a method of fabricating an isolation layer in a semiconductor device according to the present invention.

<Description of the symbols for the main parts of the drawings>

11, 101: semiconductor substrate 102, 12: pad insulating film

13, 103: nitride film 15, 105: buried insulator

17: chemical vapor deposition oxide film 19: trench

21: second thermal oxide film 25: gate oxide film

Device isolation film manufacturing method of a semiconductor device according to the present invention for achieving the above object,

Sequentially forming a pad insulating film, a nitride film, and a chemical vapor deposition oxide film on the semiconductor substrate;

Forming a trench by removing a chemical vapor deposition oxide film, a nitride film, a pad insulating film, and a semiconductor substrate of a portion intended as an element isolation region;

Forming a first thermal oxide film on an etching surface of the trench and removing the first thermal oxide layer by a wet etching method to remove defects generated during the trench formation;

Forming a second thermal oxide film on the trench etching surface;

Depositing an insulator filling the trench up to the chemical vapor deposition oxide film;

Chemical mechanical polishing the insulator until the chemical vapor deposition oxide film is exposed;

And removing the chemical vapor deposition oxide film and the nitride film by a wet etching process.

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

3A to 3I are cross-sectional views illustrating a process of forming a device isolation insulating film of a semiconductor device according to an embodiment of the present invention.

First, a pad oxide film 12 is formed on the semiconductor substrate 11 to a thickness of 50 to 200 GPa with a thermal oxide film.

Next, a nitride film 13 is formed on the pad oxide film 12 to a thickness of about 500 to 1500 kPa. (See Figure 3a)

Subsequently, a chemical vapor deposition oxide film 17 is formed on the nitride film 13 at a thickness of about 100 to 1000 kPa at 830 to 1000 ° C. In this case, the chemical vapor deposition oxide layer 17 may be replaced with an oxide layer having a faster wet etching rate than the insulating material filling the trench. (See Figure 3b)

Subsequently, a photoresist pattern (not shown) is formed on the chemical vapor deposition oxide film 18 to expose a predetermined portion as a device isolation region, and the chemical vapor deposition oxide film 17 is formed by using the photoresist pattern as an etching mask. The trench 19 is formed by removing the nitride film 13, the pad oxide film 12, and the semiconductor substrate 11 having a predetermined thickness. At this time, the semiconductor substrate 11 etch a depth of 1500 ~ 4000 4000. (See Figure 3c)

Next, a first thermal oxide layer (not shown) is formed to a thickness of 50 to 200 Å on the etching surface of the trench 19 and is removed by a wet etching method to remove defects in the trench etching surface during the formation of the trench 19. However, the over-etching is performed so that the first thermal oxide film is removed at about 100 to 300 Å. (See FIG. 3D)

Next, a second thermal oxide film 21 is formed on the etching surface of the trench 19 to have a thickness of 50 to 200 Å. (See Figure 3e)

Next, a high density plasma chemical vapor deposition oxide or ozone Teos with the entire surface: the buried insulator 15 for embedding the trench 19 by using (O ₃ tetra ethyl ortho silicate hereinafter referred to as O ₃ TEOS) To form. In this case, the buried insulator 15 is formed to cover the chemical vapor deposition oxide layer 17. (See Figure 3f)

The buried insulator 15 is then removed until the chemical vapor deposition oxide film 17 is exposed using a CMP process. (See Fig. 3g)

Next, the chemical vapor deposition oxide film 17 and the nitride film 13 are removed by a wet etching method. (See Fig. 3h)

After the gate oxide layer 25 is formed through the sacrificial oxidation process and the gate process, the active region of the semiconductor substrate 11 is formed not to be higher or lower than the buried insulator 15 filling the trench 19. . (See Figure 3i)

For reference, the etching ratios of the thermal oxide film, the chemical vapor deposition oxide film, and the high density plasma oxide film in the oxide etching solution are shown in Table 1 below.

Table 1

Etching solution thin film BOE solution HF solution Thermal oxide 1.0 1.0 High Temperature Chemical Vapor Deposition Oxide 2.3 2.6 High Density Plasma Chemical Vapor Deposition (Fixed Insulation) 1.3 1.3

As shown in Table 1, the etching rate of the chemical vapor deposition oxide is faster than the high-density plasma chemical vapor deposition oxide filling the trench, so that the etching time is shorter than the case where there is an insulator on top of the nitride film, and thus, the trench is lower than the active region of the semiconductor substrate. It is possible to prevent the height of the insulated material buried.

As described above, in the method of manufacturing a device isolation film of a semiconductor device according to the present invention, a thin nitride film, which is a chemical mechanical polishing prevention layer, and a chemical vapor deposition oxide film are formed thereon, so that a mask process is more easily performed than a mask process proceeding on the nitride film. After the chemical mechanical polishing process is performed to expose the chemical vapor deposition oxide film, the chemical vapor deposition oxide film on the upper part of the nitride film removal process has a faster wet etching rate than the insulating material filling the trench. In this case, the wet etching time can be reduced, and the etching amount of the buried insulator is reduced, thereby preventing the buried insulator from being formed lower than the active region of the semiconductor substrate.

Claims (8)

Sequentially forming a pad insulating film, a nitride film, and a chemical vapor deposition oxide film on the semiconductor substrate; Forming a trench by removing a chemical vapor deposition oxide film, a nitride film, a pad insulating film, and a semiconductor substrate of a portion intended as an element isolation region; Forming a first thermal oxide film on an etching surface of the trench and removing the first thermal oxide layer by a wet etching method to remove defects generated during the trench formation; Forming a second thermal oxide film on the trench etching surface; Depositing an insulator filling the trench up to the chemical vapor deposition oxide film; Chemical mechanical polishing the insulator until the chemical vapor deposition oxide film is exposed; And removing the chemical vapor deposition oxide film and the nitride film by a wet etching process. The method of claim 1, The chemical vapor deposition oxide film is a device isolation film manufacturing method of a semiconductor device, characterized in that formed at a thickness of about 100 ~ 1000 에서 at 830 ~ 1000 ℃. The method of claim 1, The chemical vapor deposition oxide film is a method of manufacturing a device isolation film of a semiconductor device, characterized in that formed with an insulating material having a faster etching rate than the insulating material filling the trench. The method of claim 1, The trench is formed by etching the semiconductor substrate to a depth of about 1500 ~ 4000 4000. The method of claim 1, The first thermal oxide film is a method of manufacturing a device isolation film of a semiconductor device, characterized in that formed on the sidewall of the trench to a thickness of about 50 ~ 200 Å. The method of claim 1, The wet etching process of removing the first thermal oxide film is a method of manufacturing a device isolation film of a semiconductor device, characterized in that the first thermal oxide film is over-etched so as to remove by 100 ~ 300 300. The method of claim 1, And insulating the trench to form a thickness of 3000 to 8000 Å. The method of claim 1, The insulating material filling the trench is a method of manufacturing a device isolation film of a semiconductor device, characterized in that using the O ₃ -TEOS or high density plasma oxide film.