Multi-step photomask etching with chlorine for uniformity control
Methods for etching quartz are provided herein. In one embodiment, a method of etching quartz includes providing a film stack on a substrate support disposed in a processing chamber, the film stack having a quartz layer partially exposed through a patterned layer; and etching the quartz layer of the film stack in a multi-step process including a first step of etching the quartz layer utilizing a first process gas comprising at least one fluorocarbon process gas and a chlorine-containing process gas; and a second step of etching the quartz layer utilizing a second process gas comprising at least one fluorocarbon process gas.
1. A method of etching quartz, comprising:
providing a film stack on a substrate support disposed in a processing chamber, the film stack having a quartz layer partially exposed through a patterned layer; and
etching the quartz layer of the film stack through the patterned layer in a multi-step process comprising:
a first step of etching the quartz layer utilizing a first process gas comprising at least one fluorocarbon process gas and a chlorine-containing process gas; and
a second step of etching the quartz layer utilizing a second process gas comprising at least one fluorocarbon process gas and no chlorine-containing process gas.
2. The method of claim 1 , wherein the fluorocarbon process gas comprises at least one of CF 4 , CHF 3 , C 2 F, C 4 F 6 , or C 4 F 8 .
3. The method of claim 1 , wherein the fluorocarbon process gas comprises CF 4 and CHF 3 .
4. The method of claim 1 , wherein one or both of the first or the second step of etching further comprises:
flowing about 2 to about 50 sccm of CF 4 into the processing chamber; and
flowing about 2 to about 50 sccm of CHF 3 into the processing chamber.
5. The method of claim 1 , wherein the first step of etching further comprises:
flowing at least one of Cl 2 or HCl into the processing chamber.
6. The method of claim 1 , wherein the first step of etching further comprises:
flowing Cl 2 into the processing chamber.
7. The method of claim 1 , wherein the first step of etching further comprises:
flowing about 1 to about 10 sccm of Cl 2 into the processing chamber.
8. The method of claim 1 , further comprising repeating at least one step of the multi-step process.
9. The method of claim 1 , further comprising repeating both steps of the multi-step process.
10. The method of claim 1 , further comprising the step:
biasing the quartz layer with a plurality of power pulses less than 150 Watts in at least one of the steps of the multi-step process.
11. The method of claim 10 , wherein the step of biasing further comprises:
pulsing power at a pulse frequency between about 1 to about 10 kHz.
12. The method of claim 10 , wherein the patterned layer is not photoresist and wherein the step of biasing comprises:
pulsing power with a duty cycle between about 10 to about 50 percent.
13. The method of claim 10 , wherein the patterned layer includes photoresist and wherein the step of biasing comprises:
pulsing power with a duty cycle between about 10 to about 90 percent.
14. A method of forming a photomask, comprising:
a) patterning a mask layer on a quartz layer disposed on a substrate support in a processing chamber;
b) etching the quartz layer of the film stack through the mask layer in a multi-step process comprising:
a first step of etching the quartz layer utilizing at least one fluorocarbon process gas and a chlorine-containing process gas; and
a second step of etching the quartz layer utilizing at least one fluorocarbon process gas and no chlorine-containing process gas;
c) terminating each step of etching of the quartz layer at a predefined etch depth; and
d) removing the mask layer after etching the quartz layer in the multi-step process.
15. The method of claim 14 , further comprising the step of:
biasing the quartz layer with a plurality of power pulses of less than 150 Watts in at least one of the steps of the multi-step process.
16. The method of claim 14 , further comprising repeating at least one step of the multi-step process.
17. The method of claim 14 , further comprising repeating both steps of the multi-step process.
18. The method of claim 14 , wherein the first step of etching further comprises:
flowing Cl 2 into the processing chamber.
19. The method of claim 14 , wherein the first step of etching further comprises:
flowing CF 4 and CHF 3 into the processing chamber.
20. The method of claim 14 , wherein the step of patterning a mask comprises:
patterning a layer of resist on the mask layer, wherein the mask layer comprises chromium;
etching the chromium mask layer to form openings therethrough; and
removing the layer of resist from the chromium mask layer.
21. The method of claim 14 , wherein the step of patterning a mask comprises:
patterning a first layer of resist on an opaque light-shielding layer of metal;
etching the light-shielding layer of metal to form at least a first opening and a second opening therethrough; and
patterning a second layer of resist on an opaque light-shielding layer of metal to form the mask layer, wherein the first opening in the light-shielding layer of metal remains filled with the second layer of resist after patterning.
22. A method of forming a photomask, comprising:
a) patterning a first layer of resist on a chromium layer;
b) etching the chromium layer to form at least a first opening and a second opening therethrough;
c) removing the first layer of resist;
d) patterning a second layer of resist on the chromium layer, wherein the first opening in the chromium layer remains filled with the second layer of resist after patterning; and
e) etching portions of a quartz layer exposed through the chromium layer to a depth one half a photolithography light wavelength of between about 193 to about 248 nm using a multi-step etch process comprising:
a first step of etching the quartz layer utilizing at least one fluorocarbon process gas and a chlorine-containing process gas; and
a second step of etching the quartz layer utilizing at least one fluorocarbon process gas and no chlorine-containing process gas.
23. The method of claim 22 , wherein at least one of the first or the second step of etching further comprises:
flowing CF 4 and CHF 3 into the processing chamber.
24. The method of claim 22 , wherein the first step of etching further comprises:
flowing Cl 2 into the processing chamber.
25. The method of claim 22 , further comprising the step of:
biasing the quartz layer with a plurality of power pulses of less than 150 Watts in at least one of the steps of the multi-step process.
26. The method of claim 22 , wherein one or both of the first or the second step of etching further comprises:
applying bias power of less than about 150 Watts at a duty cycle between about 10 to about 90 percent;
inductively coupling the less than about 600 Watts of RF power to an antenna disposed proximate the process chamber;
flowing less than about 15 sccm of CF 4 into the processing chamber; and
flowing less than about 30 sccm of CHF 3 into the processing chamber.
27. The method of claim 22 , wherein the first step of etching the quartz layer further comprises:
applying bias power of less than about 150 Watts at a duty cycle between about 10 to about 90 percent;
inductively coupling the less than about 600 Watts of RF power to an antenna disposed proximate the process chamber; and
flowing less than about 10 sccm of Cl 2 into the processing chamber.
28. The method of claim 22 , further comprising repeating at least one step of the multi-step process.
29. The method of claim 22 , further comprising repeating both steps of the multi-step process.