Pulsed bias plasma process to control microloading
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.
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 at substantially the same etch rate 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 claim 1 , wherein the etch gas comprises a deposition component and an etch component.
4. 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.
5. The method, as recited in claim 4 , wherein the net deposition is directional and the net etch is directional.
6. The method, as recited in claim 1 , wherein the conductive layer is a tungsten containing layer.
7. The method, as recited in claim 1 , wherein the pulsed bias has a frequency between 10 Hz and 5,000 Hz.
8. 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.
9. The method, as recited in claim 8 , wherein the silicon containing component is a halogenated silane.
10. The method, as recited in claim 9 , wherein the oxygen-containing component is oxygen (O 2 ).
11. The method, as recited in claim 8 , wherein the oxygen-containing component is oxygen (O 2 ).
12. The method, as recited in claim 1 , wherein the pulsed bias voltage is a pulsed DC voltage.
13. A method of etching a conductive layer through a mask with wider and narrower features, comprising:
(a) flowing a steady state etch gas comprising:
a silicon containing component; and
an oxygen containing component;
(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 at substantially the same etch rate into the conductive layer using the plasma formed from the etch gas.
14. The method of etching recited in claim 13 wherein the silicon containing component and oxygen containing component comprise siloxane.
15. The method of etching recited in claim 13 wherein the oxygen containing component comprise at least one of ozone and H 2 O.
16. The method of etching recited in claim 13 wherein the silicon containing component comprises material in accordance with the general formula R—SiO where the R group comprises an alkyl group.
17. The method of etching recited in claim 13 wherein the silicon containing component further comprises and material having a boiling point of 150° C. and below.
18. The method of etching recited in claim 13 wherein the silicon containing component comprises a siloxane material.
19. The method of etching recited in claim 13 wherein the silicon containing component comprises a material similar to a siloxane material where the bridging oxygen is replaced with a nitrogen.
20. The method of etching recited in claim 13 wherein the silicon containing component comprises a material similar to a siloxane material comprising at least one of tetramethyldisilazane, hexamethyldisilazane, or N-methyl-N-silyl-Silanamine.
21. The method of etching recited in claim 13 wherein the silicon containing component comprises at least one of an organosilicon compound based on the structural unit Si A x Z (4-x) (where A is selected from the group H, F, Cl, Br, and I, where Z is an alkyl group and where x is from 0-4).