Method and apparatus for etching a substrate

• US 6,187,685 B1
• Filed: 02/08/1999
• Issued: 02/13/2001
• Est. Priority Date: 08/01/1997
• Status: Expired due to Term

• Current Assignee: Surface Technology Systems Plc (KLA Corporation)
• Original Assignee: Surface Technology Systems Plc (KLA Corporation)
• Inventors: Hopkins, Janet, Hynes, Alan Michael, Johnston, Ian Ronald, Lea, Leslie Michael, Bhardwaj, Jyoti Kiron, Ashraf, Huma
• Primary Examiner(s): POWELL, WILLIAM A
• Application Number:
  US09/245,861
• Time in Patent Office: 736 Days
• Field of Search: 438/9, 438/14, 438/694, 438/695, 438/705, 438/710, 438/712, 438/714, 438/718, 438/719, 438/723, 438/735, 438/743, 216/37, 216/59, 216/60, 216/67, 216/79, 156/345.MT, 156/345.P
• US Class Current: 438/710
• CPC Class Codes: H01L 21/30655 comprising alternated and repeated etching and passivation steps, e.g. Bosch process
• CPC Class Codes: H01L 21/32137 of silicon-containing layers

Abstract

There is disclosed a method and apparatus for etching a substrate. The method comprises the steps of etching a substrate or alternately etching and depositing a passivation layer. A bias frequency, which may be pulsed, may be applied to the substrate and may be at or below the ion plasma frequency.

Claims

1. A method of etching a feature in a substrate in a chamber, the method comprising alternately etching by means of a plasma and depositing a passivation layer by means of a plasma, wherein a bias frequency is applied to the substrate which is at or below the ion plasma frequency.

2. A method according to claim 1, wherein the bias frequency is pulsed.

5. A method according to claim 1, wherein the bias frequency is produced by an RF or DC bias power supply.

6. A method according to claim 1, wherein the substrate is a semiconductor.

7. A method according to claim 1, wherein the substrate comprises an insulating underlayer.

8. A method according to claim 1, wherein the bias frequency is at or below 4 MHz.

9. A method according to claim 8, wherein the bias frequency is in the range of 50 kHz to 380 kHz.

10. A method according to claim 1, further comprising an etching and passivation step which is carried out at a higher pressure than the etching or alternate etching and deposition step.

11. A method according to claim 10, wherein the etching and passivation step carried out at a higher pressure is started when the underlayer is approached.

12. A method according to claim 10, further comprising an end-point detection step to determine when to switch from the etching or alternate etching and deposition first step to the further etching and passivating step.

13. A method according to any one of claim 2, wherein the pulse off time is greater than 100 μ

s.

14. A method according to claim 2, wherein the pulse off time is applied for between 10% to 90% of the time.

15. A method according to claim 1, further comprising the step of providing a magnetic filter to partially or completely divide the volume of the chamber in which the plasma is formed from the volume in which the substrate is positioned.

19. A method according to claim 11, further comprising an end-point detection step to determine when to switch from the etching or alternate etching and depositing first step to the further etching and passivating step.

3. A method of etching a feature in a substrate in a chamber, the method comprising alternately etching by means of a plasma and depositing a passivation layer by means of a plasma, wherein a pulsed bias frequency is applied to the substrate.

4. A method of etching a feature in a substrate in a chamber by means of a plasma, the method comprising applying a pulsed bias frequency to the substrate which is at or below the ion plasma frequency.

16. An apparatus for etching a feature in a substrate, the apparatus comprising a chamber, means for alternately etching the substrate by means of a plasma and depositing a passivation layer by means of a plasma, and means for providing a bias frequency to the substrate which is at or below the ion plasma frequency.

17. An apparatus for etching a feature in a substrate, the apparatus comprising a chamber, means for alternately etching the substrate by means of a plasma and depositing a passivation layer by means of a plasma, and means for providing a pulsed bias frequency to the substrate.

18. An apparatus for etching a feature in a substrate, the apparatus comprising a chamber, means for etching the substrate by means of a plasma and means for providing a pulsed bias frequency to the substrate which is at or below the ion plasma frequency.