PLASMA ETCHING METHOD AND COMPUTER-READABLE STORAGE MEDIUM

Abstract

In a plasma etching method for plasma-etching an etching stop film after plasma-etching a low-k film in a structure in which a wiring layer, the etching stop film made of an SiC-based material, the low-k film and an etching mask are formed in that order on a substrate, the method includes the step of arranging the structure having the plasma-etched low-k film in a processing chamber in which a first and a second electrode are provided to face each other at vertically separated locations. The plasma etching method further includes the steps of introducing a processing gas containing NF3 into the processing chamber; generating a plasma by applying a high frequency power to one of the first and the second electrode; and applying a DC voltage to said one of the electrodes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will become apparent from the following description of embodiments, given in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic cross sectional view of an example of a plasma etching apparatus utilized in implementing the present invention;

FIG. 2 shows a matching unit connected to a first high-frequency power supply in the plasma etching apparatus shown in FIG. 1;

FIG. 3 illustrates a cross sectional view illustrating a structure of a semiconductor wafer W used in implementing a first embodiment of the present invention;

FIG. 4 presents a schematic view showing a state in which an undercut is formed in etching an etching stop film;

FIG. 5 represents a diagram illustrating changes in V_dc and thickness of a plasma sheath when a direct current voltage has been applied to an upper electrode in the plasma etching apparatus shown in FIG. 1;

FIG. 6 provides comparative plots respectively representing plasma states in case when the direct current voltage is applied to the upper electrode and in case when no direct current voltage is applied thereto in the plasma etching apparatus shown in FIG. 1;

FIG. 7 depicts a schematic diagram showing a state in which the etching stop film is etched by the embodiment of the present invention.

FIG. 8 offers a diagram describing a structure of a sample used for examining actual effects of a method of the present invention;

FIG. 9 describes a diagram illustrating a state in which a trench etching is performed on the sample of FIG. 8;

FIG. 10 shows a schematic diagram depicting a state in which the etching stop film is etched without applying a DC voltage to the upper electrode;

FIG. 11 describes a schematic diagram illustrating a state in which the etching stop film is etched by applying a DC voltage of −400 V to the upper electrode;

FIG. 12 provides a schematic diagram showing a state in which the etching stop film is etched by applying a DC voltage of −800 V to the upper electrode;

FIG. 13 represents a schematic diagram of an example of another plasma etching apparatus that can be employed for implementing the present invention;

FIG. 14 offers a cross sectional view showing another example of a plasma etching apparatus that can be employed in implementing the present invention;

FIG. 15 presents a schematic diagram showing a further example of a plasma etching apparatus that can be employed in implementing the present invention; and

FIG. 16 offers a cross sectional view showing a still further example of a plasma etching apparatus that can be employed in implementing the present invention;

Claims

1. A plasma etching method for plasma-etching an etching stop film after plasma-etching a low-k film in a structure in which a wiring layer, the etching stop film made of an SiC-based material, the low-k film and an etching mask are formed in that order on a substrate, the method comprising the steps of: arranging the structure having the plasma-etched low-k film in a processing chamber in which a first and a second electrode are provided to face each other at vertically separated locations;introducing a processing gas containing NF3 into the processing chamber;generating a plasma by applying a high frequency power to one of the first and the second electrode; andapplying a DC voltage to said one of the electrodes.

2. The plasma etching method of claim 1, wherein an absolute value of the DC voltage is greater than or equal to 400 V.

3. The plasma etching method of claim 1, wherein the low-k film is an SiOC-based film.

4. The plasma etching method of claim 2, wherein the low-k film is an SiOC-based film.

5. The plasma etching method of claim 1, wherein the DC voltage is a previously obtained value by which a required etching shape was obtained in a test object.

6. The plasma etching method of claim 2, wherein the DC voltage is a previously obtained value by which a required etching shape was obtained in a test object.

7. The plasma etching method of claim 1, wherein the first and the second electrode are an upper and a lower electrode, respectively, and the high frequency power for plasma generation and the DC voltage are applied to the first electrode.

8. The plasma etching method of claim 2, wherein the first and the second electrode are an upper and a lower electrode, respectively, and the high frequency power for plasma generation and the DC voltage are applied to the first electrode.

9. The plasma etching method of claim 5, wherein the first and the second electrode are an upper and a lower electrode, respectively, and the high frequency power for plasma generation and the DC voltage are applied to the first electrode.

10. The plasma etching method of claim 6, wherein the first and the second electrode are an upper and a lower electrode, respectively, and the high frequency power for plasma generation and the DC voltage are applied to the first electrode.

11. The plasma etching method of claim 7, wherein a high frequency power for ion attraction is applied to the second electrode.

12. The plasma etching method of claim 8, wherein a high frequency power for ion attraction is applied to the second electrode.

13. The plasma etching method of claim 9, wherein a high frequency power for ion attraction is applied to the second electrode.

14. The plasma etching method of claim 10, wherein a high frequency power for ion attraction is applied to the second electrode.

15. A computer readable storage medium for storing therein a computer-executable control program, wherein the control program, when executed in a computer, controls a plasma processing apparatus to perform the plasma etching method described in claim 1.

16. A computer readable storage medium for storing therein a computer-executable control program, wherein the control program, when executed in a computer, controls a plasma processing apparatus to perform the plasma etching method described in claim 2.

17. A computer readable storage medium for storing therein a computer-executable control program, wherein the control program, when executed in a computer, controls a plasma processing apparatus to perform the plasma etching method described in claim 3.

18. A computer readable storage medium for storing therein a computer-executable control program, wherein the control program, when executed in a computer, controls a plasma processing apparatus to perform the plasma etching method described in claim 5.

19. A computer readable storage medium for storing therein a computer-executable control program, wherein the control program, when executed in a computer, controls a plasma processing apparatus to perform the plasma etching method described in claim 7.

20. A computer readable storage medium for storing therein a computer-executable control program, wherein the control program, when executed in a computer, controls a plasma processing apparatus to perform the plasma etching method described in claim 11.