INORGANIC RAPID ALTERNATING PROCESS FOR SILICON ETCH

• US 20110244686A1
• Filed: 03/31/2010
• Published: 10/06/2011
• Est. Priority Date: 03/31/2010
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Aso, Tsuyoshi, Rusu, Camelia
• Granted Patent: US 8,574,447 B2
• Time in Patent Office: Days
• US Class Current: 438/694
• CPC Class Codes: H01L 21/30655 comprising alternated and repeated etching and passivation steps, e.g. Bosch process
• CPC Class Codes: H01L 21/76898 formed through a semiconductor substrate

Abstract

A method for etching features into a silicon substrate disposed below a mask in a plasma processing chamber is provided. The silicon substrate is etched through the mask comprising a plurality of cycles, wherein each cycle comprises a sidewall deposition phase and an etch phase. The sidewall deposition phase comprises providing a flow of sidewall inorganic deposition phase gas comprising a silicon containing compound gas and at least one of oxygen, nitrogen or NO_x, into the plasma processing chamber, forming a plasma from the sidewall deposition phase gas in the plasma processing chamber, and stopping the flow of the sidewall deposition gas into the plasma processing chamber. The etch phase comprises, providing a flow of an etching gas comprising a halogen component, forming a plasma from the etching gas in the plasma processing chamber, and stopping the flow of the etching gas.

Claims

1. A method for etching features into a silicon substrate disposed below a mask in a plasma processing chamber, comprising:

etching the silicon substrate through the mask comprising a plurality of cycles, wherein each cycle comprises;

a sidewall inorganic deposition phase, comprising

providing a flow of sidewall deposition phase gas comprising a silicon containing compound gas and at least one of oxygen, nitrogen or NO_x, wherein x=1, 2 into the plasma processing chamber;

forming a plasma from the sidewall deposition phase gas in the plasma processing chamber; and

stopping the flow of the sidewall deposition gas into the plasma processing chamber; and

an etch phase, comprising;

providing a flow of an etching gas comprising a halogen component into the plasma processing chamber;

forming a plasma from the etching gas in the plasma processing chamber; and

stopping the flow of the etching gas into the plasma processing chamber.

2. The method, as recited in claims 1, wherein the etching gas further comprises oxygen, nitrogen, or NO_x.

3. The method, as recited in claim 2, wherein each sidewall deposition phase is between 0.1 seconds and 2 seconds.

11. The method, as recited in claim 1, wherein the deposition phase gas is halogen free.

12. The method, as recited in claim 11, wherein the etch phase is free of the silicon containing compound gas.

13. The method, as recited in claim 1, wherein the deposition phase gas has a flow ratio of the silicon containing compound gas to oxygen, nitrogen or NO of between 1:

1 to 30;

1

14. The method, as recited in claim 1, wherein the plurality of cycles is at least 10 cycles.

15. The method, as recited in claim 1, wherein the halogen component comprises fluorine.

16. The method, as recited in claim 1, wherein the halogen component is SF₆.

4. The method, as recited in 3, wherein each etch phase is between 0.6 seconds and 10 seconds.

5. The method, as recited in claim 4, wherein the mask is a photoresist mask through which the silicon is etched during the etch.

6. The method, as recited in claim 5, wherein the silicon containing compound gas is selected from the group consisting of SiF₄, SiCl₄, SiH₄, SiH_xCl_y(x+y=4)), and SiH_xF_y.

7. The method, as recited in claim 4, wherein the deposition phase gas has a flow ratio of the silicon containing compound gas to oxygen, nitrogen or NO of between 1:

1 to 30;

1

8. The method, as recited in claim 4, wherein the plurality of cycles is at least 10 cycles.

9. The method, as recited in claim 4, wherein the halogen component comprises fluorine.

10. The method, as recited in claim 4, wherein the halogen component is SF₆.

17. A method for etching features into a silicon substrate disposed below a mask in a plasma processing chamber, comprising:

etching the silicon substrate through the mask comprising at least 10 cycles, wherein each cycle comprises;

a sidewall inorganic deposition phase, comprising

providing a flow of sidewall deposition phase gas comprising a silane gas and at least one of oxygen, nitrogen or NO_x, wherein x=1, 2 into the plasma processing chamber;

forming a plasma from the sidewall deposition phase gas in the plasma processing chamber; and

stopping the flow of the sidewall deposition gas into the plasma processing chamber; and

an etch phase, comprising;

providing a flow of an etching gas comprising SF₆ into the plasma processing chamber;

forming a plasma from the etching gas in the plasma processing chamber; and

stopping the flow of the etching gas into the plasma processing chamber.

18. The method, as recited in claims 17, wherein the etching gas further comprises oxygen, nitrogen, or NOx.

19. An apparatus for selectively etching a silicon nitride layer with respect to a silicon oxide based layer over a substrate, comprising:

a plasma processing chamber, comprising;

a chamber wall forming a plasma processing chamber enclosure;

a substrate support for supporting a wafer within the plasma processing chamber enclosure;

a pressure regulator for regulating the pressure in the plasma processing chamber enclosure;

at least one electrode for providing power to the plasma processing chamber enclosure for sustaining a plasma;

a gas inlet for providing gas into the plasma processing chamber enclosure; and

a gas outlet for exhausting gas from the plasma processing chamber enclosure;

a gas source in fluid connection with the gas inlet, comprising;

a silicon containing compound gas source;

an oxygen, nitrogen, or NO_x gas source; and

a halogen component gas source; and

a controller controllably connected to the gas source and the at least one electrode, comprising;

at least one processor; and

computer readable media, comprising;

computer readable code for etching the silicon substrate through the mask comprising a plurality of cycles, wherein each cycle comprises;

computer readable code for providing a sidewall deposition phase, comprising

computer readable code for providing a flow of sidewall deposition phase gas comprising a silicon containing compound gas from the silicon containing compound gas source and at least one of oxygen, nitrogen or NO_x, wherein x=1, 2 from the oxygen, nitrogen or NO gas source into the plasma processing chamber;

computer readable code for forming a plasma from the sidewall deposition phase gas in the plasma processing chamber; and

computer readable code for stopping the flow of the sidewall deposition gas into the plasma processing chamber; and

computer readable cod for providing an etch phase, comprising;

computer readable code for providing a flow of an etching gas comprising a halogen component into the plasma processing chamber from the halogen component gas source;

computer readable code for forming a plasma from the etching gas in the plasma processing chamber; and

computer readable code for stopping the flow of the etching gas into the plasma processing chamber.