Method for photomask fabrication utilizing a carbon hard mask

1. A method of fabricating a photomask, comprising:

depositing a carbon layer on an optically transparent substrate having a chromium layer;

depositing and patterning a photoresist layer on the carbon layer;

etching the carbon layer through the photoresist layer to form a patterned hard mask;

etching the chromium layer in the presence of a plasma formed from a process gas containing BCl 3 and CO through the carbon hard mask; and

removing the hard mask.

2. The method of claim 1 , wherein providing the process gas comprises:

flowing about 10 to about 500 sccm of CO into the processing chamber.

3. The method of claim 1 , wherein providing the process gas comprises:

flowing about 100 to about 300 sccm of CO into the processing chamber.

4. The method of claim 1 , further comprising:

removing the patterned photoresist layer contemporarily with etching the carbon layer.

5. The method of claim 1 further comprising:

removing the patterned photoresist layer while etching the chromium layer.

6. The method of claim 1 further comprising:

removing the patterned photoresist layer while removing the hard mask.

7. The method of claim 1 , wherein the hard mask is removed in-situ a processing chamber in which the chromium layer is etched.

8. A method of fabricating a photomask, comprising:

depositing an α-carbon layer on an optically transparent substrate having a chromium layer;

depositing and patterning a photoresist layer on the α-carbon layer;

etching the α-carbon layer through the photoresist layer to form a patterned hard mask;

etching the chromium layer in the presence of a plasma formed from a process gas containing at least BCl 3 and CO through the carbon hard mask, wherein the substrate is biased during chromium etching; and

removing the hard mask.

9. The method of claim 8 , wherein etching the chromium layer further comprises:

flowing about 150 sccm of CO into the processing chamber;

maintaining chamber pressure at around 3 mTorr;

applying a plasma source power at around 300 Watts; and

supplying a plasma bias power at around 8 Watts.

10. The method of claim 8 further comprising:

removing the patterned photoresist layer contemporarily with etching the carbon layer.

11. The method of claim 8 further comprising:

removing the patterned photoresist layer while at least one of etching the chromium layer or removing the hard mask.

12. The method of claim 8 , wherein etching the chromium layer further comprises:

flowing about 10 to about 500 sccm of CO into the processing chamber.

13. The method of claim 8 , wherein etching the chromium layer further comprises:

flowing about 100 to about 300 sccm of CO into the processing chamber.

14. The method of claim 8 , wherein the hard mask is removed in-situ a processing chamber in which the chromium layer is etched.

15. The method of claim 8 , wherein biasing the substrate during etching the chromium layer further comprises:

biasing the substrate with a power of less than 100 W.

16. The method of claim 15 , wherein the biasing the substrate during etching the chromium layer further comprises:

pulsing the bias power.

17. A method of fabricating a photomask, comprising:

depositing an α-carbon layer on an optically transparent substrate having a chromium layer;

depositing and patterning a photoresist layer on the α-carbon layer;

etching the α-carbon layer through the photoresist layer to form a patterned hard mask;

etching the chromium layer in the presence of a plasma formed from a process gas containing CO and BCl 3 through the carbon hard mask, wherein the substrate is biased with a power of less than 100 W during chromium etching; and

removing the hard mask.

18. The method of claim 17 , wherein the hard mask is removed in-situ a processing chamber in which the chromium layer is etched.