SILICON ETCH WITH PASSIVATION USING PLASMA ENHANCED OXIDATION

• US 20100105209A1
• Filed: 10/23/2008
• Published: 04/29/2010
• Est. Priority Date: 10/23/2008
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Winniczek, Jaroslaw W., Chebi, Robert P.
• Granted Patent: US 8,173,547 B2
• Time in Patent Office: Days
• US Class Current: 438/696
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/32137 of silicon-containing layers

Abstract

A method and apparatus for etching a silicon layer through a patterned mask formed thereon are provided. The silicon layer is placed in an etch chamber. An etch gas comprising a fluorine containing gas and an oxygen and hydrogen containing gas is provided into the etch chamber. A plasma is generated from the etch gas and features are etched into the silicon layer using the plasma. The etch gas is then stopped. The plasma may contain OH radicals.

Claims

1. A method of etching a silicon layer through a patterned mask formed thereon using an etch chamber in which the silicon layer is placed, the method comprising:

providing an etch gas comprising a fluorine containing gas and an oxygen and hydrogen containing gas into the etch chamber;

generating a plasma from the etch gas;

etching features into the silicon layer using the plasma; and

stopping the etch gas.

2. The method according to claim 1, wherein the plasma contains OH radicals.

3. The method according claim 1, further comprising:

providing a bias voltage during said etching.

4. The method according to claim 1, wherein said oxygen and hydrogen containing gas contains water vapor.

5. The method according to claim 4, wherein said etching includes:

forming a passivation layer containing SiO_xH_y on a sidewall of the features being etched, where x≧

1 and y≧

1.

6. The method according to claim 1, wherein said oxygen and hydrogen containing gas contains alcohol.

7. The method according to claim 6, wherein said etching includes:

forming a passivation layer containing SiC_nO_xH_y on a sidewall of the features being etched, where n≧

0, x≧

1, y≧

0, and n and y are not both zero.

8. The method according to claim 1, wherein the fluorine containing gas contains SF₆.

9. The method according to claim 8, wherein the fluorine containing gas further contains SiF₄.

10. The method according to claim 1, wherein the etch gas further contains O₂.

11. The method according to claim 10, wherein the etch gas further contains at least one of CO₂ or CO.

12. The method according to claim 1, wherein the etch gas and the oxygen and hydrogen containing gas are introduced into the etch chamber separately from different gas inlets provided at different locations.

13. A method of etching a silicon layer through a patterned mask formed thereon using an etch chamber in which the silicon layer is placed, the method comprising:

providing an etch gas comprising a fluorine containing gas into an upstream plasma chamber;

generating a plasma from the etch gas;

introducing a reaction medium from the plasma into the etch chamber;

providing a passivation gas containing oxygen and hydrogen into the etch chamber such that the reaction medium contains OH radicals;

etching features into the silicon layer using the reaction medium; and

stopping the reaction medium and the passivation gas.

14. The method according claim 13, further comprising:

providing a bias voltage during said etching.

15. The method according to claim 13, wherein said passivation gas contains at least one of water vapor or alcohol.

16. The method according to claim 15, wherein said etching includes:

forming a passivation layer containing SiO_xH_y on a sidewall of the features being etched, where x≧

1 and y≧

1.

17. The method according to claim 15, wherein said etching includes:

forming a passivation layer containing SiC_nO_xH_y on a sidewall of the features being etched, where n≧

0, x≧

1, and y≧

0, and n and y are not both zero.

18. The method according to claim 13, wherein the fluorine containing gas contains SF₆.

19. An apparatus for etching features in a silicon layer through a patterned mask, comprising:

a plasma processing chamber, comprising;

a chamber wall forming a plasma processing chamber enclosure;

a substrate support for supporting a substrate 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;

at least one RF power source electrically connected to the at least one electrode;

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;

an etching gas source in fluid connection with the gas inlet, comprising;

an fluorine containing gas source; and

an oxygen and hydrogen containing gas source; and

a controller controllably connected to the gas source, the RF bias source, and the at least one RF power source, comprising;

at least one processor; and

computer readable media, comprising;

computer readable code for etching the silicon layer, comprising;

computer readable code for flowing a fluorine containing gas from the fluorine containing gas source into the plasma chamber;

computer readable code for flowing an oxygen and hydrogen containing gas from the oxygen and hydrogen containing gas source into the plasma chamber;

computer readable code for forming a plasma from the fluorine containing gas and the oxygen and hydrogen containing gas;

computer readable code for providing a bias voltage;

computer readable code for etching features into the silicon layer; and

computer readable code for stopping the fluorine containing gas and the oxygen and hydrogen containing gas.