PULSED BIAS PLASMA PROCESS TO CONTROL MICROLOADING

• US 20110281438A1
• Filed: 11/18/2008
• Published: 11/17/2011
• Est. Priority Date: 11/29/2007
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Fu, Qian, Liu, Shenjian, Pu, Bryan, Lee, Wonchul
• Granted Patent: US 8,609,546 B2
• Time in Patent Office: Days
• US Class Current: 438/720
• CPC Class Codes: H01L 21/32136 using plasmas

Abstract

A method for etching a conductive layer through a mask with wider and narrower features is provided. A steady state etch gas is flowed. A steady state RF power is provided to form a plasma from the etch gas. A pulsed bias voltage is provided during the steady state etch gas flow, wherein the pulsed bias voltage has a frequency between 1 to 10,000 Hz. Wider and narrower features are etched into the conductive layer using the plasma formed from the etch gas.

Claims

1. A method of etching a conductive layer through a mask with wider and narrower features, comprising:

(a) flowing a steady state etch gas;

(b) providing a steady state RF power to form a plasma from the etch gas;

(c) providing a pulsed bias voltage during the steady state etch gas flow, wherein the pulsed bias voltage has a frequency between 1 to 10,000 Hz; and

(d) etching wider and narrower features into the conductive layer using the plasma formed from the etch gas.

2. The method, as recited in claim 1, wherein the pulsed bias voltage reduces microloading between the wider and narrower features.

3. The method, as recited in any of claim 1, wherein the etch gas comprises a deposition component and an etch component.

18. The method, as recited in claim 3, wherein when the bias voltage is low, a net deposition results, and when the bias voltage is high, a net etch results.

19. The method, as recited in claim 18, wherein the net deposition is directional and the net etch is directional.

20. The method, as recited in claim 1, wherein the conductive layer is a tungsten containing layer.

21. The method, as recited in claim 1, wherein the pulsed bias has a frequency between 10 Hz and 5,000 Hz.

22. The method, as recited in claim 3, wherein the deposition component of the etch gas comprises:

a silicon containing component; and

an oxygen containing component.

23. The method, as recited in claim 22, wherein the silicon containing component is a halogenated silane.

24. The method, as recited in claim 23, wherein the oxygen-containing component is oxygen (O₂).

25. The method, as recited in claim 22, wherein the oxygen-containing component is oxygen (O₂).

26. The method, as recited in claim 1, wherein the pulsed bias voltage is a pulsed DC voltage.

4-11. -11. (canceled)

12. A computer implemented method of etching an etch layer through a mask with wider and narrower features, comprising

(a) flowing a steady state etch gas, comprising a deposition component and an etch component into the plasma chamber;

(b) providing a steady state RF power to form a plasma from the etch gas in the plasma chamber;

(c) providing a pulsed bias voltage during the steady state etch gas flow to the plasma chamber, wherein the pulsed bias voltage has a frequency between 1 to 10,000 Hz; and

(d) etching the etch layer using the plasma formed from the etch gas to form wider and narrower etch features with reduced microloading.

13. The computer implemented method, as recited in claim 12, wherein the pulsed bias has a frequency between 10 Hz and 5,000 Hz.

14. The computer implemented method, as recited in any of claim 13, wherein the deposition component of the etch gas comprises:

a silicon containing component; and

an oxygen containing component.

15. The computer implemented method, as recited in claim 14, wherein the silicon containing component is a halogenated silane.

16. The method, as recited in claim 14, wherein the oxygen-containing component is oxygen (O₂).

17. An apparatus for etching an etch layer through a mask with wider and narrower features, comprising:

a plasma reactor, comprising;

a plasma processing chamber;

an RF-transparent window;

a transformer coupled plasma (TCP) coil adjacent to the RF-transparent window for providing power for sustaining a plasma;

a TCP power supply electrically connected to the TCP coil;

a chuck electrode for supporting a semiconductor substrate within the plasma processing chamber;

a bias power supply electrically connected to the chuck electrode;

a bias power controller for controlling the bias power supply, wherein the bias power controller is able to cause the bias power supply to provide a pulsed bias power between 1 to 10,000 Hz;

a pressure control valve and a pump for regulating the pressure in the plasma processing chamber;

a gas source, comprising an etch gas component source and a deposition gas component source; and

a controller controllably connected to the gas source and the TCP coil, comprising;

at least one processor; and

computer readable media, comprising;

computer readable code for flowing a steady state etch gas, comprising a deposition component and an etch component into the plasma processing chamber;

computer readable code for providing a steady state RF power to form a plasma from the etch gas in the plasma processing chamber;

computer readable code for providing a pulsed bias voltage during the steady state etch gas flow to the plasma processing chamber, wherein the pulsed bias voltage has a frequency between 1 to 10,000 Hz; and

computer readable code for etching the etch layer using the plasma formed from the etch gas to form wider and narrower etch features with reduced microloading.