Method for depositing conformal amorphous carbon film by plasma-enhanced chemical vapor deposition (PECVD)

1. A method of forming an amorphous carbon layer on a substrate, comprising:

positioning a substrate in a substrate processing chamber;

performing a deposition cycle, comprising:

introducing a hydrocarbon source having a carbon to hydrogen atom ratio greater than 1:2 into the processing chamber;

introducing a plasma initiating gas selected from the group consisting of hydrogen, helium, argon, nitrogen, and combinations thereof into the processing chamber, with the hydrocarbon source having a volumetric flow rate to plasma initiating gas volumetric flow rate ratio of 1:2 or greater;

generating a plasma in the processing chamber at a RF power density of 1 W/cm 2 or less, a pressure of 2 Torr or greater, and a temperature of about 300° C. to about 480° C.;

forming a conformal amorphous carbon layer on the substrate; and

performing a purge processing step after forming the conformal amorphous carbon layer by flowing a purge gas through the processing chamber, wherein the purge processing step comprises a pause step time and forming the conformal amorphous carbon layer comprises a deposition step time, wherein the ratio of the pause step time to the deposition step time is from about 100:1 to about 1:100; and

repeating the deposition cycle from 2 to 50 times.

2. The method of claim 1 , wherein the deposition cycle further comprises introducing a dilutant gas into the processing chamber with the hydrogen precursor, the plasma-initiating gas, or both.

3. The method of claim 1 , wherein the hydrocarbon source has a carbon to hydrogen atom ratio of 2:3 or greater and comprises one or more compounds selected from the group of acetylene, vinylacetylene, benzene, styrene, toluene, xylene, pyridine, acetophenone, phenol, furan, C 3 H 2 , C 5 H 4 , monofluorobenzene, difluorobenzenes, tetrafluorobenzenes, and hexafluorobenzene.

4. The method of claim 1 , wherein the hydrocarbon gas volumetric flow rate to plasma initiating gas volumetric flow rate ratio is from about 1:1 to about 1:2.

5. The method of claim 1 , wherein the RF power density is applied from about 0.01 to about 1 W/cm 2 .

6. The method of claim 1 , wherein the pressure is from about 2 Torr to about 20 Torr.

7. The method of claim 1 , wherein the RF power is provided by a dual-frequency system.

8. The method of claim 1 , wherein the conformal amorphous carbon layer has a conformality from about 30% to about 100%.

9. The method of claim 1 , wherein the purge gas comprises an inert gas or a hydrocarbon source gas.

10. A method of forming an amorphous carbon layer on a substrate, comprising:

positioning a substrate in a substrate processing chamber;

performing a deposition cycle, comprising:

introducing a hydrocarbon source having a carbon to hydrogen atom ratio greater than 1:2 into the processing chamber;

introducing a plasma initiating gas selected from the group consisting of hydrogen, helium, argon, nitrogen, and combinations thereof into the processing chamber, with the hydrocarbon source having a volumetric flow rate to plasma initiating gas volumetric flow rate ratio of 1:2 or greater;

generating a plasma in the processing chamber at a RF power density of 1 W/cm 2 or less, a pressure of 2 Torr or greater, and a temperature of about 300° C. to about 480° C.;

forming a conformal amorphous carbon layer on the substrate; and

performing a purge processing step after forming the conformal amorphous carbon layer by flowing a purge gas through the processing chamber, wherein the purge gas is excited into a plasma; and

repeating the deposition cycle from 2 to 50 times.

11. The method of claim 1 , wherein each deposition cycle deposits between 2% and 50% of the thickness of the conformal amorphous carbon layer.

12. A method of forming an amorphous carbon layer on a substrate, comprising:

positioning a substrate in a substrate processing chamber;

introducing a hydrocarbon source having a carbon to hydrogen atom ratio of greater than 1:2 into the processing chamber;

introducing a plasma initiating gas consisting of helium into the processing chamber, with the hydrocarbon source having a volumetric flow rate to plasma initiating gas volumetric flow rate ratio of 1:2 or greater, wherein the hydrocarbon source and the plasma initiating gas are introduced into the processing chamber by a gas distributor position between 400 mils and 600 from the substrate surface;

generating a plasma in the processing chamber at a RF power of 1 W/cm 2 or less a pressure of 9 Torr, and a temperature of 75° C.; and

forming a conformal amorphous carbon layer on the substrate.

13. The method of claim 12 , wherein the conformal amorphous carbon layer has a conformality of about 72%.

14. The method of claim 13 , wherein the conformal amorphous carbon layer is formed over about 9 feature definitions per 1600 nm 2 of substrate surface.

15. The method of claim 12 , wherein the gas distributor position is at 500 mils from the substrate surface.

16. The method of claim 15 , wherein the conformal amorphous carbon layer has a conformality of 90% or greater.

17. The method of claim 16 , wherein the conformal amorphous carbon layer is formed over between 4 to 20 feature definitions per 1600 nm 2 of substrate surface.