KR100241518B1 - Method of manufacturing field oxide film in semiconductor device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a field oxide film of a semiconductor device. In particular, polysilicon having columnar grains in a poly buffered LOCOS (PBL) technology in a device isolation technology of a semiconductor device is used in an oxidation process. After oxidizing the grain boundary by using the oxide film as a mask, the silicon substrate has a plurality of fine grooves, and a field oxide film is formed in the field oxide film forming process, thereby producing a bird's beak at the edge. ) And a method of manufacturing a field oxide film of a semiconductor device capable of improving electrical characteristics such as punchthrough voltage by increasing the volume of the field oxide film inside the silicon substrate.

Description

Method of manufacturing field oxide film in semiconductor device

1 (a) to 1 (g) are cross-sectional views showing steps of manufacturing a field oxide film of a semiconductor device according to the present invention.

* Explanation of symbols for main parts of the drawings

1 silicon substrate 2 pad oxide film

3: polysilicon 3A: grain

3B: grain boundary 4: nitride film

5: photoresist 6: oxide film

6A: residual oxide film 7: microgroove

8: field oxide film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a field oxide film of a semiconductor device. In particular, polysilicon having columnar grains in a poly buffered LOCOS (PBL) technology in a device isolation technology of a semiconductor device is used in an oxidation process. After oxidizing the grain boundary by using the oxide film as a mask, the silicon substrate has a plurality of fine grooves, and a field oxide film is formed in the field oxide film forming process, thereby producing a bird's beak at the edge. The present invention relates to a method for manufacturing a field oxide film of a semiconductor device capable of controlling the electrical conductivity and improving electrical characteristics such as a punchthrough voltage.

PBL technology, which is used as a conventional device isolation technology, can control the buzz beak to a certain extent, but there is a problem such as punch-through voltage due to the insufficient depth of the field oxide film entering the silicon substrate as the semiconductor device becomes smaller than 0.5 µm. Occurs.

Accordingly, the present invention minimizes the occurrence of the buzz beak, and increases the volume of the field oxide film by deeply forming the field oxide film inside the silicon substrate, thereby improving electrical characteristics such as punch-through voltage and the like, and also improving device isolation function. Its purpose is to provide a method for producing a field oxide film.

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

1 (a) to 1 (g) are cross-sectional views showing a step of manufacturing a field oxide film of a semiconductor device according to the present invention, and FIG. 1 (a) shows a pad oxide film 2 by oxidizing a silicon substrate 1. ) To form a thin layer of about 50 to 100 kPa, and then depositing polysilicon 3 on the upper portion of the film, 500 to 1000 kPa and nitride film 4 on the order of 1500 to 2000 kPa, respectively, and photoresist 5 on the nitride film 4 The state which patterned the said photoresist 5 using the field oxide film mask after apply | coating is shown.

The polysilicon 3 has a columnar structure, and has a columnar crystal grains 3A and grain boundaries 3B.

FIG. 1 (b) shows a state where the exposed portion of the nitride film 4 is dry-viewed by the etching process using the patterned photoresist 5 to expose the surface of the lower polysilicon 3.

FIG. 1 (c) shows a state in which a part of the surface of the polysilicon 3 becomes an oxide film 6 by removing the patterned photoresist 5 and then oxidizing the exposed surface of the polysilicon 3. .

When the polysilicon 3 is oxidized, the grain boundary 3B portion of the polysilicon 3 has a higher oxidation rate than the grain 3A portion, so that the grain boundary 3B portion is more oxidized.

FIG. 1 (d) shows a state in which the surface of the oxide film 6 is etched by a wet etching method to expose the surface of the crystal grains 3A and leave the remaining oxide film 6A only at the grain boundary 3B.

FIG. 1 (e) shows the silicon substrate 1 by etching the polysilicon 3, the pad oxide film 2 and the silicon substrate 1 to a predetermined depth by a dry etching method using the residual oxide film 6A as an etching mask. It shows a state in which a plurality of fine grooves 7 are formed.

Since the pad oxide film 2 is sufficiently thin during the dry etching, the loss of the remaining oxide film 6A, which is an etching mask, is extremely small, and the depth of the microgroove 7 is about 500 to 1000 Å.

FIG. 1 (f) shows a state in which the field oxide film 8 is formed by performing a field oxidation process under the state shown in FIG. 1 (e).

FIG. 1 (g) shows a state in which the field oxide film 8 is completed by completely removing the nitride film 4 by wet etching, the polysilicon 3 by dry etching, and then again removing the pad oxide film 2 by wet etching. will be.

Since the field oxide film of the present invention based on the above is formed deep inside the silicon substrate and its volume is large, it is possible to manufacture a field oxide film that is electrically stable and extremely small in Buzzbee, and thus can be easily applied to manufacture a highly integrated semiconductor device. have.

Claims (4)

In the method of manufacturing a field oxide film of a semiconductor device, a silicon oxide substrate 1 is oxidized to form a pad oxide film 2, and a polysilicon 3 having a columnar structure is formed on the upper portion thereof to a predetermined thickness. 3) forming a nitride film 4 on a predetermined thickness, applying the photoresist 5 on the nitride film 4, and then patterning the photoresist 5 using a field oxide mask; Dry etching the exposed portion of the nitride film 4 by an etching process using the patterned photoresist 5 from the step to expose the lower surface of the polysilicon 3, and the patterned photoresist 5 from the step ), And then oxidizing the exposed surface of the polysilicon (3) so that a part of the surface of the polysilicon (3) to the oxide film (6), and from the step by etching the surface of the oxide film (6) by wet etching Remaining remaining oxide film 6A The polysilicon (3), the pad oxide film (2) and the silicon substrate (1) are etched to a predetermined depth by the etching step and a dry etching method using the remaining oxide film (6A) as an etching mask from the step. Forming a plurality of microgrooves (7). Performing a field oxidation process from the above step, and then completely removing the remaining nitride film 4, the polysilicon 3, and the pad oxide film 2 in order to complete the field oxide film 8; Field oxide film production method. The method of manufacturing a field oxide film of a semiconductor device according to claim 1, wherein when the surface of the polysilicon 3 is oxidized, the grain boundary 3B portion of the polysilicon 3 has a higher oxidation rate than the grain 3A portion. . The method of claim 1, wherein the remaining oxide film 6A is formed by removing the oxide film 6 on the crystal grain 3A of the polysilicon 3 and leaving the oxide film 6 at the grain boundary 3B. Field oxide film production method of a semiconductor device. The thickness of the pad oxide film 2 is 50 to 100 microns, the polysilicon 3 is 500 to 1000 microns, the nitride film 4 is 1500 to 2000 microns, and the depth of the fine grooves 7 A method for producing a field oxide film of a semiconductor device, characterized in that it is 500 to 1000 GPa.