Method and apparatus for etching
Embodiments of the invention relate to a substrate etching method and apparatus. In one embodiment, a method for etching a substrate in a plasma etch reactor is provided that includes a) depositing a polymer on a substrate in an etch reactor, b) etching the substrate using a gas mixture including a fluorine-containing gas and oxygen in the etch reactor, c) etching a silicon-containing layer the substrate using a fluorine-containing gas without mixing oxygen in the etch reactor, and d) repeating a), b) and c) until an endpoint of a feature etched into the silicon-containing layer is reached.
1. A method for etching a substrate in a plasma etch reactor comprising:
a) depositing a polymer on a substrate in an etch reactor;
b) etching the substrate using a gas mixture including a fluorine-containing gas and oxygen in the etch reactor, wherein the gas mixture includes less than 20 sccm of oxygen;
c) etching a silicon-containing layer disposed on the substrate using a fluorine-containing gas without mixing oxygen in the etch reactor; and
d) repeating a), b) and c) until an endpoint of a feature etched into the silicon-containing layer is reached.
2. The method of claim 1 , wherein b) further comprises:
etching the substrate in the presence of at least one of He or HeO 2 .
3. The method of claim 1 , wherein b) is performed at a lower pressure than c).
4. The method of claim 1 , wherein b) is performed using a higher bias power than c).
5. The method of claim 1 , wherein c) further comprises:
forming a plasma from SF 6 .
6. The method of claim 1 , wherein b) further comprises:
forming a plasma from SF 6 and O 2 .
7. The method of claim 1 , wherein b) further comprises:
forming a plasma from a gas mixture of SF 6 and O 2 and at least one of He and HeO 2 ; and wherein c) further comprises:
forming a plasma from SF 6 .
8. The method of claim 1 , wherein b) further comprises:
etching the substrate in the presence of HeO 2 .
9. The method of claim 1 further comprising:
flowing a backside process gas out from between an edge of the substrate and a substrate assembly and into the plasma etch reactor, wherein the backside process gas is a gas which affects the rate of etch or polymerization during d) by reacting with materials in the plasma etch reactor.
10. The method of claim 9 , wherein the backside process gas includes at least oxygen.
11. The method of claim 1 further comprising:
purging the etch reactor between a) and b).
12. The method of claim 11 , wherein purging further comprises:
flowing at least one of He or HeO 2 into the etch reactor.
13. The method of claim 11 , wherein purging further comprises:
forming a plasma from at least one of He or HeO 2 in the etch reactor.
14. The method of claim 13 , wherein purging further comprises:
biasing the substrate with RF power.
15. A method for etching a substrate in a plasma etch reactor comprising:
a) depositing a polymer on silicon-containing layer disposed on a substrate in an etch reactor;
b) isotropically etching the polymer and silicon-containing layer in the etch reactor using a gas mixture including a fluorine-containing gas and oxygen maintained at a first pressure, wherein the gas mixture includes less than 20 sccm of oxygen;
c) anisotropically etching the silicon-containing layer in the etch reactor using a fluorine-containing gas without mixing oxygen maintained a second pressure that is greater than the first pressure, wherein the fluorine-containing gas comprising the gas mixture is selected from the group consisting of SF 6 , NF 3 , CF 4 , CHF 3 , ClF 3 , BrF 3 , IF 3 and derivatives thereof; and
d) repeating a), b) and c) until an endpoint of a feature etched into the silicon-containing layer is reached.
16. The method of claim 15 further comprising:
purging the etch reactor between a) and b) with at least one of He or HeO 2 .
17. The method of claim 16 , wherein purging further comprises:
forming a plasma from at least one of He or HeO 2 in the etch reactor during purging; and
biasing the substrate during purging.
18. The method of claim 15 further comprising:
flowing a backside process gas out from between an edge of the substrate and a substrate assembly and into the plasma etch reactor, wherein the backside process gas is a gas which affects the rate of etch or polymerization during d) by reacting with materials in the plasma etch reactor.
19. The method of claim 18 , wherein the backside process gas comprises at least oxygen.
20. The method of claim 19 , wherein the backside process gas further comprises helium, wherein the ratio of helium to oxygen is between about 50:50 and about 70:30 by weight or mass.