KR19980028369A - Device Separator Formation Method of Semiconductor Device - Google Patents

Abstract

The present invention relates to a method of forming a device isolation layer of a semiconductor device, wherein during the device isolation process using a shallow trench, the semiconductor substrate is not etched by etching the semiconductor substrate together when the nitride film is etched as the device isolation region. By etching the lower exposed semiconductor substrate using oxide spacers formed on both sidewalls of the nitride removed region, a trench is formed to form a gate oxide film having a good shape without forming a conventional gate oxide film having a stage formed after the gate oxide film growth. It is possible to achieve the operation of the normal device even at a high gate voltage to improve the reliability of the semiconductor device.

Description

Device Separator Formation Method of Semiconductor Device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a device isolation film of a semiconductor device. In particular, in the device isolation process of forming a device isolation film using a shallow trench, a gate oxide film is formed by forming a gate oxide film using a trench using an oxide spacer. The present invention relates to a method of forming a device isolation film of a semiconductor device capable of improving the reliability of a semiconductor device by allowing a normal device operation to be performed even after growth.

A conventional technique for forming a semiconductor device isolation layer using a shallow trench will be described with reference to the accompanying drawings.

1A to 1F are cross-sectional views illustrating a device isolation film forming process step of a semiconductor device according to the prior art.

Referring to FIG. 1A, a pad oxide film 3 and a nitride film 5 are sequentially formed on the semiconductor substrate 1, and a photosensitive film pattern 7 is formed on the nitride film 5.

Next, the lower nitride layer 5 and the pad oxide layer 3 are etched using the photoresist pattern 7, but the semiconductor substrate 1 is also etched at a predetermined depth to form the trench 10.

Referring to FIG. 1B, an oxide film 9 is deposited on the entire structure after removing the photosensitive film 7.

Referring to FIG. 1C, the deposited oxide layer 9 is planarized by a planarization etching process or a chemical mechanical polishing (CMP) process.

Referring to FIG. 1D, the exposed nitride film 5 is etched and removed.

Referring to FIG. 1E, the gate oxide film 3 is grown. At this time, a jaw (part A) is formed at the boundary between the grown gate oxide film 3 and the trench 10 filled with the oxide film 9, as shown in FIG. 1F.

When the gate oxide film 3 is grown in the above shape, the gate oxide film 3 is easily destroyed even at a low voltage, thereby lowering the reliability of the semiconductor device.

Therefore, in order to solve the above problems, the present invention is advantageous by forming oxide spacers on both exposed sidewalls of the nitride nitride layer without forming trenches during the etching of the nitride layer, and then etching the lower exposed semiconductor substrate using the oxide spacer to form a trench. It is an object of the present invention to provide a method of forming a device isolation layer of a semiconductor device in which a normal operation of a device may be performed even at a high gate voltage by forming a gate oxide film having a shape.

1A to 1F illustrate a process of fabricating an isolation layer of a semiconductor device according to the related art.

2A through 2G are diagrams illustrating a process of fabricating an isolation layer of a semiconductor device according to the present disclosure.

* Description of the main parts of the drawings

1,21: semiconductor substrate 3,23: pad oxide film

5,25 nitride film 7,27 photosensitive film

9,31 oxide film 28 oxide film for spacer formation

29: oxide film spacer

According to the device isolation film forming method of the present invention for achieving the above object, the step of depositing a pad oxide film, a nitride film on the semiconductor substrate in turn, forming a device isolation mask on the nitride film, and the device isolation mask Etching the nitride film of the region intended as the device isolation region, forming an oxide film having a predetermined thickness on the entire structure, etching the oxide film to form oxide spacers on both sidewalls of the nitride film, and Etching the semiconductor substrate exposed to the lower portion using an oxide spacer to form a trench having a predetermined depth, depositing an oxide layer over the entire structure to fill the trench, and planarizing the oxide layer on the upper portion by a planarization etching process. Removing the nitride film exposed by the planarization etching; After the turning step is characterized in that consisting of a step of growing a gate oxide film.

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

2A to 2G are cross-sectional views illustrating a process of fabricating an isolation layer of a semiconductor device in accordance with the method of the present invention.

Referring to FIG. 2A, a pad oxide film 23 and a nitride film 25 are sequentially deposited on the semiconductor substrate 21.

Next, a device isolation mask 27 is formed on the nitride film 25.

Referring to FIG. 2B, the nitride film 25 in the region intended as the device isolation region is etched using the device isolation mask 27.

Next, an oxide film 28 having a predetermined thickness is deposited on the entire structure.

In this case, the thickness of the oxide film 28 deposited to form a spacer after the nitride 25 film is etched to the device isolation region is 150 to 1500 mW.

Referring to FIG. 2C, the oxide film 28 is etched to leave the oxide film 28 on the sidewall of the nitride film 25 to form an oxide film spacer 29.

Next, the exposed semiconductor substrate 21 is etched using the oxide spacer 29 to form a trench 30 having a predetermined depth.

At this time, the length B of one side lower portion of the oxide spacer 29 is set to 150 to 1500 mW.

Referring to FIG. 2D, an oxide film 31 is deposited on the entire structure to fill the inside of the trench 30.

Meanwhile, in the step of forming the oxide film 31 over the entire structure after the trench formation, the oxide spacer 29 is separately removed before the oxide film 31 is deposited over the entire structure, and then ion implanted to improve device characteristics. After the process, the oxide film 31 may be deposited.

Referring to FIG. 2E, the upper oxide layer 31 is planarized by using a planarization etching or a CMP process.

In this case, after the planarization etching, the oxide layer 31 and the nitride layer 23 are formed at the same height and exposed together.

Referring to FIG. 2F, the exposed nitride film 23 is removed.

Referring to FIG. 2G, the gate oxide layer 23 is grown after a cleaning process.

It can be seen that the grown gate oxide film 23 has a shape in which the jaw is normally grown, rather than a chin, as in the conventional gate oxide film (3 in FIG. 1E).

As described above, the oxide spacers formed on both sidewalls of the etched nitride film are not formed when the nitride film is etched into the device isolation region during the device isolation process using the shallow trench according to the method of the present invention. By forming the trench by etching the exposed semiconductor substrate in the lower portion, the gate oxide film having a good shape can be obtained without forming a conventional gate oxide film having a stage even after the gate oxide film growth so that normal operation of the device can be achieved even at a high gate voltage. It is possible to improve the reliability of the semiconductor device

Claims (5)

Depositing a pad oxide film and a nitride film on the semiconductor substrate in order, forming a device isolation mask on the nitride film, etching the nitride film in a region intended as an device isolation region by using the device isolation mask; Forming an oxide film having a predetermined thickness over the entire structure, etching the oxide film to form oxide spacers on both sidewalls of the nitride film, and etching a semiconductor substrate exposed to the lower portion using the oxide spacers to a predetermined depth. Forming a trench in the trench; depositing an oxide layer over the entire structure to fill the trench; planarizing the oxide layer on the planar etching process; removing the nitride layer exposed by the planarization etching process; And growing a gate oxide film after the cleaning process. Isolation film forming method of the semiconductor device. The method of claim 1, wherein a thickness of an oxide layer deposited to form a spacer after the nitride layer is etched into the device isolation region is 150 to 1500 kW. The method of claim 1, wherein the length B of one lower side of the oxide spacer is 150 μm to 1500 μm. The method of claim 1, wherein after the trench forming process, the oxide spacer is separately removed when the oxide film is deposited on the entire structure, and the oxide film is deposited after the ion implantation process. 2. The method of claim 1, wherein a CMP process is used as the planarization process.