Plasma Etching Method and Apparatus

Patent metadata

Field	Value
Publication number	US-2025006537-A1
Application number	US-202318393632-A
Country	US
Kind code	A1
Filing date	Dec 21, 2023
Priority date	Jun 30, 2023
Publication date	Jan 2, 2025
Grant date	—

Abstract

During a plasma etching of a semiconductor substrate, a cooling gas is supplied to a lower surface of the semiconductor substrate at an associated pressure. The electrostatic chuck is switched between a first bipolar mode of operation in which a positive voltage is applied to a first electrode and a negative voltage is applied to a second electrode and a second bipolar mode of operation in which a negative voltage is applied to the first electrode and a positive voltage is applied to the second electrode. The pressure of the cooling gas is reduced when the ESC is switched between the first and second bipolar modes of operation with respect to the pressure at other times during the plasma etching so that the semiconductor substrate remains positioned on the substrate support.

First claim

1 . A method of plasma etching a semiconductor substrate comprising:
positioning the semiconductor substrate on a substrate support within a chamber so that an upper surface of the semiconductor substrate can be exposed to a plasma etching and a lower surface of the semiconductor substrate is supported by the substrate support, wherein the substrate support comprises a bipolar electrostatic chuck (“ESC”) and a cooling gas system for supplying a cooling gas to the lower surface at an associated pressure, and wherein the ESC comprises at least a first electrode and a second electrode; plasma etching the semiconductor substrate; and removing the semiconductor substrate from the substrate support after the plasma etching is completed; in which, during the plasma etching: a cooling gas is supplied to the lower surface of the semiconductor substrate at an associated pressure; the ESC is switched between a first bipolar mode of operation in which a positive voltage is applied to the first electrode and a negative voltage is applied to the second electrode, and a second bipolar mode of operation in which a negative voltage is applied to the first electrode and a positive voltage is applied to the second electrode; and the pressure of the cooling gas is reduced when the ESC is switched between the first bipolar mode of operation and the second bipolar mode of operation with respect to the pressure at other times during the plasma etching so that the semiconductor substrate remains positioned on the substrate support.

2 . The method according to claim 1 , wherein the pressure of the cooling gas is reduced to a pressure of less than 1 Torr when the ESC is switched between the first bipolar mode of operation and the second bipolar mode of operation.

3 . The method according to claim 1 , wherein the ESC is switched between the first bipolar mode of operation and the second bipolar mode of operation a plurality of times during the plasma etching.

4 . The method according to claim 3 , wherein the ESC is switched between the first bipolar mode of operation and the second bipolar mode of operation at least three times during the plasma etching.

5 . The method according to claim 1 , wherein the semiconductor substrate attains a temperature of at least 140° C. during the plasma etching.

6 . The method according to claim 1 further comprising exposing the semiconductor substrate to a plasma formed in an inert gas or inert gaseous mixture between the steps of plasma etching the semiconductor substrate and removing the semiconductor substrate from the substrate support.

7 . The method according to claim 6 , wherein the inert gas or inert gaseous mixture comprises He and/or Ar.

8 . The method according to claim 1 , wherein the semiconductor substrate is moved by the cooling gas if the ESC is switched between the first bipolar mode of operation and the second bipolar mode of operation without reducing the pressure of the cooling gas.

9 . The method according to claim 1 , wherein the semiconductor substrate is an InP semiconductor substrate.

10 . The method according to claim 1 , wherein the ESC comprises a dielectric material and during the switching of the ESC between the first bipolar mode of operation and the second bipolar mode of operation a resistivity of the dielectric material is in a range from 10 12 -10 13 ohms-cm.

11 . A system for plasma etching a semiconductor substrate using the method according to claim 1 , the system comprising:
the chamber; the substrate support disposed within the chamber, wherein the substrate support comprises the bipolar electrostatic chuck (“ESC”) and the cooling gas system for supplying the cooling gas to the lower surface at the associated pressure, and wherein the ESC comprises at least the first electrode and the second electrode; a plasma generation device for sustaining the plasma within the chamber for etching the semiconductor substrate; a mechanism for removing the semiconductor substrate from the substrate support; and a controller configured to control the system to perform the plasma etching of the semiconductor substrate, wherein the ESC is switched between the first bipolar mode of operation, wherein the positive voltage is applied to the first electrode and the negative voltage is applied to the second electrode, and the second bipolar mode of operation in which the negative voltage is applied to the first electrode and the positive voltage is applied to the second electrode; and the pressure of the cooling gas is reduced when the ESC is switched between the first bipolar mode of operation and the second bipolar mode of operation with respect to the pressure at other times during the plasma etching so that the semiconductor substrate remains positioned on the substrate support.

12 . The system according to claim 11 , wherein the plasma generation device is an Inductively Coupled Plasma (ICP) device.

13 . The system according to claim 11 further comprising a bypass valve in fluid communication with the cooling gas system and a gas pump, wherein the controller is configured to open and shut the bypass valve so that the pressure of the cooling gas is reduced when the ESC is switched between the first bipolar mode of operation and the second bipolar mode of operation by opening the bypass valve to exhaust cooling gas by the gas pump.

14 . The system according to claim 11 , wherein the electrodes of the ESC are non-interdigitated.

15 . The system according to claim 11 , wherein the ESC comprises Al 2 O 3 .

Assignees

• Spts Technologies Ltd

Inventors

• Beachey Adam S

Classifications

• H10P50/242

  of Group IV materials · CPC title

• H10P72/722 Primary

  Details of electrostatic chucks · CPC title

• H10P72/72

  using electrostatic chucks · CPC title

• H10P72/0434

  mainly by convection · CPC title

• H10P72/0421 Primary

  for drying etching · CPC title