Method of forming tunnel oxide film in semiconductor device

1. A method of forming a tunnel oxide film in a semiconductor device, comprising the steps of:

(a) forming a first oxide film on a semiconductor substrate, and then forming a photo resist pattern exposing the first oxide film in a memory cell area and a low voltage transistor area;

(b) removing a predetermined thickness of the exposed first oxide film and the photo resist pattern sequentially; and

(c) removing the remaining first oxide film completely and then forming a second oxide film on a whole surface.

2. The method of claim 1 , wherein the first oxide film is a pure oxide film, and it is grown at a temperature in the range of 750° C. to 850° C. to have a thickness in the range of 350 Å to 600 Å.

3. The method of claim 1 , wherein the step (b) further comprises the steps of:

removing a predetermined thickness of the first oxide film by using a 300:1 BOE for a period in the range of 1,730 seconds to 1,735 seconds;

removing the photo resist pattern by using a H 2 SO 4 solution; and

performing a cleaning process using an SC-1 solution to remove pollutants such as organic components or particles.

4. The method of claim 1 , wherein a thickness of the first oxide film remaining after the step (b) is in the range of 17 Å to 23 Å.

5. The method of claim 1 , wherein the first oxide film is removed by performing a cleaning process using a 50:1 HF solution in the step (c).