KR19990005535A - Method of forming isolation film for semiconductor device - Google Patents

Abstract

The present invention relates to a method of forming an isolation layer of a semiconductor device. In particular, when a contact hole is formed on an STI layer after forming an isolation layer using STI (Shallow Trench Isolation), the damage of the isolation layer due to misalignment can be prevented. A method for forming a separator. The isolation layer forming method of the semiconductor device may include forming first and second insulating films on a semiconductor substrate, defining a trench region to selectively remove the second and first insulating films of the trench region, and the second insulating film. Forming a trench by selectively removing the semiconductor substrate by an etching process using a mask, forming a third insulating layer at a position lower than an upper surface of the semiconductor substrate in the trench, and a second including the third insulating layer Forming a fourth insulating film on an entire surface of the insulating film, forming a fifth insulating film on the fourth insulating film, and planarizing the fifth insulating film and the fourth insulating film until the upper surface of the third insulating film is exposed; And etching back the third insulating film and the second insulating film until the semiconductor substrate is exposed.

Description

Method of forming isolation film for semiconductor device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a separator of a semiconductor device. In particular, when a contact hole is formed on an STI layer after forming a separator using STI (Shallow Trench Isolation), the damage of the separator due to misalignment can be prevented. A method for forming a separator of a semiconductor device

Hereinafter, a method of forming a separator of a conventional semiconductor device will be described with reference to the accompanying drawings.

1A to 1E are cross-sectional views of a process of forming a separator of a conventional semiconductor device.

First, as shown in FIG. 1A, the first thermal oxide film 2 and the nitride film 3 are sequentially formed on the semiconductor substrate 1, and then the photosensitive film PR is coated on the nitride film 3. Next, after the isolation region is defined and selectively patterned the photoresist film PR of the isolation region, the etching process using the patterned photoresist film PR as a mask is performed on the nitride film 3, the thermal oxide film 2 and the semiconductor substrate ( 1) are sequentially etched to form trenches 4 in the semiconductor substrate 1.

As shown in FIG. 1B, the photosensitive film PR is removed. Subsequently, a second thermal oxide film 5 is formed on the surface of the semiconductor substrate 1 in the trench 4. Then, the first oxide film 6 is formed on the upper side of the second thermal oxide film 5 and the entire surface of the nitride film 3 in the trench 4 using chemical vapor deposition.

As shown in Fig. 1C, the first oxide film 6 is polished by chemical mechanical polishing (CMP). At this time, polishing is performed until the upper surface of the nitride film 3 is exposed.

As shown in FIG. 1D, after removing the nitride film 3, the first oxide film 6 is etched to be flush with the upper surface of the semiconductor substrate 1 to complete the isolation oxide film 6a. In this case, the semiconductor substrate 1 on which the isolation oxide film 6a is not formed is an active region.

As shown in Fig. 1E, the second oxide film 7 and the third oxide film 8 are sequentially formed on the semiconductor substrate 1 and the isolation oxide film 6a. Subsequently, a selective patterning process (photolithography process + etching process) is performed to form a semiconductor device in an active region where the isolation oxide film 6a is not formed, or to form a contact hole. The top side is exposed. At this time, a defective region 9 due to misalignment occurred in the A portion. This is because the etching selectivity of the second and third oxide films 7 and 8 formed on the semiconductor substrate 1 and the isolation oxide film 6a is the same.

In the conventional method of forming the isolation layer of a semiconductor device, an oxide film is used as the isolation material forming material formed in the STI. As the integration of the semiconductor device increases, the possibility of misalignment is increased, so that the defect of the isolation oxide formed in the STI is high. The likelihood of occurrence of a leakage current increases, resulting in a problem of lowering the reliability of the semiconductor device.

The present invention has been made to solve the problems of the conventional method of forming an isolation film of a semiconductor device as described above. It is an object of the present invention to provide a method for forming an isolation layer of a semiconductor device capable of preventing damage to the isolation oxide layer even if this occurs.

1A to 1E are cross-sectional views of forming a separator of a conventional semiconductor device.

2A to 2G are cross-sectional views of an isolation film forming process of a semiconductor device according to the present invention.

Explanation of symbols for main parts of the drawings

11 semiconductor substrate 12 first insulating film

13 second insulating film 14 trench

15: third insulating film 16a: insulating film

17: fifth insulating film 18: sixth insulating film

19: seventh insulating film 20: eighth insulating film

In the method for forming an isolation layer of a semiconductor device according to the present invention, forming a first and a second insulating film on a semiconductor substrate, defining a trench region to selectively remove the second and first insulating film of the trench region, Forming a trench by selectively removing the semiconductor substrate by an etching process using an insulating layer as a mask; forming a third insulating layer at a position lower than an upper surface of the semiconductor substrate in the trench; and including the third insulating layer Forming a fourth insulating film on the entire surface of the second insulating film, forming a fifth insulating film on the fourth insulating film, and planarizing the fifth insulating film and the fourth insulating film until the upper surface of the third insulating film is exposed. And etching back the third insulating film and the second insulating film until the semiconductor substrate is exposed.

Such a method of forming an isolation layer of a semiconductor device of the present invention will be described with reference to the accompanying drawings.

2A to 2G are cross-sectional views of the isolation film forming process of the semiconductor device of the present invention.

First, as shown in FIG. 2A, the first insulating film 12 and the second insulating film 13 are sequentially formed on the semiconductor substrate 11, and then the photosensitive film PR is coated on the second insulating film 13. . Next, after defining the isolation region to selectively pattern the photoresist film PR of the isolation region, the second insulation film 13, the second insulation film 12, and the etching process using the patterned photoresist film PR as a mask. The semiconductor substrate 11 is sequentially etched to form trenches 14 in the semiconductor substrate 11. In this case, the first insulating film 12 is formed of an oxide film, and the second insulating film 13 is formed of a nitride film.

As shown in FIG. 2B, the photosensitive film PR is removed. Subsequently, a third insulating film 15 is formed on the surface of the semiconductor substrate 11 in the trench 14. Then, the fourth insulating film 16 is formed on the entire surface of the second insulating film 13 above the third insulating film 15 and the semiconductor substrate 11 in the trench 14 using chemical vapor deposition. Subsequently, the fourth insulating film 16 is polished by chemical mechanical polishing (CMP). At this time, polishing is performed until the upper side surface of the second insulating layer 13 is exposed. In this case, the third insulating film 15 is a thermal oxide film formed by thermally oxidizing the semiconductor substrate 11. The fourth insulating film 16 is formed by chemical vapor deposition and is formed of an oxide film.

As shown in FIG. 2C, the fourth insulating film 16 is etched by dry etching so as to be positioned only in the trench 14, thereby completing the insulating insulating film 16a. In more detail, the semiconductor substrate 11 is positioned at a lower position than the upper surface of the semiconductor substrate 11.

As shown in FIG. 2D, the fifth insulating film 17 and the sixth insulating film 18 are sequentially formed on the entire surface of the insulating insulating film 16a and the second insulating film 13. In this case, the fifth insulating film 17 is formed of a nitride film, and the sixth insulating film 18 is formed of an oxide film.

As shown in Fig. 2E, the sixth and fifth insulating films 18 and 17 are polished and planarized by chemical mechanical mirror polishing. At this time, polishing is performed until the sixth insulating layer 16 is completely removed.

As shown in FIG. 2F, the fifth and second insulating layers 17 and 13 are etched back to expose the surface of the semiconductor substrate 11 on both sides of the trench 14. At this time, the fifth insulating layer 17 remains on the isolation insulating layer 16a in the trench 14. That is, a fifth insulating film 17 made of a nitride film is formed on the isolation insulating film 16a formed of an oxide film.

As shown in FIG. 2G, the seventh insulating film 19 and the eighth insulating film 20 are sequentially formed on the upper surfaces of the fifth insulating film 17 and the semiconductor substrate 11 by using an oxide film by chemical vapor deposition. Subsequently, a selective patterning process (photolithography process + etching process) is performed to form a semiconductor device in an active region where the isolation oxide film 16a is not formed, or to form a contact hole. The top side is exposed. At this time, even if a misalignment occurs, the fifth and seventh insulating layers 18 and 19 and the fifth insulating layer 17 have different etching selectivity, so that the fifth insulating layer 17 is not damaged.

In the method for forming an isolation film of a semiconductor device according to the present invention, a nitride film is formed on an isolation oxide film formed in an STI, so that the isolation insulating film is damaged during an etching process of an oxide film formed on the semiconductor substrate to insulate or isolate the semiconductor device. By eliminating the possibility of getting a high voltage, the possibility of occurrence of leakage current is suppressed to improve the reliability of the highly integrated semiconductor device.

Claims (3)

Forming first and second insulating films on the semiconductor substrate; Defining a trench region to selectively remove second and first insulating layers of the trench region; Forming a trench by selectively removing the semiconductor substrate by an etching process using the second insulating layer as a mask; Forming a third insulating film at a position lower than an upper surface of the semiconductor substrate in the trench; Forming a fourth insulating film on an entire surface of the second insulating film including the third insulating film; Forming a fifth insulating film on the fourth insulating film; Planarizing the fifth insulating film and the fourth insulating film until the upper surface of the third insulating film is exposed; And etching back the third insulating film and the second insulating film until the semiconductor substrate is exposed. The method of claim 1, wherein the fourth insulating layer is formed of a material having an etch selectivity different from that of the third insulating layer. The method of claim 2, wherein the fourth insulating film is formed of a nitride film.