Method for processing target object

1. A method for processing a target object including mask by using a capacitively coupled plasma processing apparatus, which includes a processing chamber that provides a processing space, a lower electrode, a mounting table for mounting the target object thereon, and an upper electrode having a silicon top plate facing the mounting table with the processing space interposed therebetween, the method comprising:

a first step of supplying a first gas containing a silicon-containing gas into the processing chamber where the target object is accommodated;

a second step of generating a plasma of a rare gas in the processing chamber after executing the first step;

a third step of generating a plasma of a second gas containing oxygen gas in the processing chamber after executing the second step; and

a fourth step of generating a plasma of a rare gas in the processing chamber after executing the third step,

wherein a silicon oxide film is formed by repeatedly executing a sequence including the first step to the fourth step, and

wherein a negative DC voltage is applied to the upper electrode in at least any one of the second step to the fourth step.

2. The method of claim 1 , wherein the silicon-containing gas is an aminosilane gas and no plasma is generated in the first step.

3. The method of claim 1 , wherein the silicon-containing gas is a halogenated silicon gas and a plasma of the first gas is generated in the first step.

4. The method of claim 3 , wherein the silicon-containing gas is SiCl 4 gas.

5. The method of claim 3 , wherein the first gas further contains a rare gas and a plasma of the rare gas is generated in the first step,

wherein the second gas further contains a rare gas and a plasma of the rare gas is generated in the third step, and

wherein the first step to the fourth step are sequentially executed while maintaining the plasma of the rare gas.

6. The method of claim 5 , wherein a flow rate of the rare gas supplied into the processing chamber in the fourth step is greater than a flow rate of the rare gas supplied into the processing chamber in the third step.

7. The method of claim 3 , wherein in the first step, a condition of a high pressure and a low power is set by setting a pressure in the processing chamber to 13.33 Pa or above and a high frequency power for plasma generation to 100 W or less.

8. The method of claim 3 , wherein in the first step, a high frequency bias power for ion attraction is not supplied to the lower electrode.

9. The method of claim 1 , wherein the target object further includes an organic film and the mask is formed on the organic film, the method further comprising:

etching the silicon oxide film by a plasma generated in the processing chamber such that a part of the silicon oxide film formed along the sidewall of the mask remains; and

etching the organic film by a plasma generated in the processing chamber.

10. The method of claim 9 , wherein the target object further includes an etching target layer that is a silicon oxide film and the organic film is formed on the etching target layer, the method further comprising:

after the etching of the organic film, etching the etching target layer by a plasma generated in the processing chamber.

11. The method of claim 9 , wherein the target object further includes a silicon-containing anti-reflection film formed on the organic film, and

wherein the mask is a resist mask formed on the anti-reflection film, the method further comprising:

between the etching of the silicon oxide film and the etching of the organic film, etching the anti-reflection film by a plasma generated in the processing chamber.

12. The method of claim 11 , further comprising: before the repetitive execution of the sequence, generating a plasma in the processing chamber and irradiating secondary electrons to the mask by applying a negative DC voltage to the upper electrode.

13. The method of claim 9 , further comprising: before the repetitive execution of the sequence, etching an anti-reflection film, on which a resist mask is formed, by a plasma generated in the processing chamber to make the mask from the anti-reflection film.

14. The method of claim 13 , further comprising: before the etching of the anti-reflection film, generating a plasma in the processing chamber and irradiating secondary ions to the resist mask by applying a negative DC voltage to the upper electrode.

15. The method of claim 13 , further comprising: after the etching of the anti-reflection film and before the repeated execution of the sequence, forming a protective film made of silicon oxide on the target object.