Tin oxide films in semiconductor device manufacturing
Tin oxide film on a semiconductor substrate is etched selectively in a presence of silicon (Si), carbon (C), or a carbon-containing material (e.g., photoresist) by exposing the substrate to a process gas comprising hydrogen (H 2 ) and a hydrocarbon. The hydrocarbon significantly improves the etch selectivity. In some embodiments an apparatus for processing a semiconductor substrate includes a process chamber configured for housing the semiconductor substrate and a controller having program instructions on a non-transitory medium for causing selective etching of a tin oxide layer on a substrate in a presence of silicon, carbon, or a carbon-containing material by exposing the substrate to a plasma formed in a process gas that includes H 2 and a hydrocarbon.
1. A method of processing a semiconductor substrate, the method comprising:
(a) providing a semiconductor substrate having an exposed layer of tin oxide, wherein the semiconductor substrate is exposed to a tin-containing precursor and an oxygen-containing precursor to provide the tin oxide layer;
(b) selectively etching the tin oxide layer in a presence of a material selected from the group consisting of silicon (Si), carbon (C), and a carbon-containing material with an etch selectivity of at least 10 by exposing the semiconductor substrate to a plasma formed in a process gas comprising H 2 and a hydrocarbon, such that a carbon-containing polymer is formed on the semiconductor substrate, wherein a ratio of H 2 to hydrocarbon in the process gas is at least 5.
2. The method of claim 1 , wherein the tin-containing precursor is an alkyl substituted tin amide.
3. The method of claim 1 , wherein the tin-containing precursor is selected from the group consisting of tetrakis(dimethylamino) tin, tetrakis(ethylmethylamino) tin, N 2 , N 3 -di-tert-butyl-butane-2,3-diamino-tin(II), and 1,3-bis(1,2methylethyl)-4,5-dimethyl-(4R, 5R)-1,3,2-diazastannolidin-2-ylidine.
4. The method of claim 1 , wherein the tin-containing precursor is tetrakis(dimethylamino) tin.
5. The method of claim 1 , wherein the semiconductor substrate is exposed sequentially to the tin-containing precursor and the oxygen-containing precursor.
6. The method of claim 1 , wherein the method comprises purging a process chamber housing the semiconductor substrate with an inert gas between the exposing of the tin-containing precursor and the oxygen-containing precursor.
7. The method of claim 1 , wherein the oxygen-containing precursor is selected from the group consisting of ozone, water, oxygen, hydrogen peroxide, and NO.
8. The method of claim 1 , wherein each of the tin-containing precursor and the oxygen-containing precursor is independently combined with a carrier gas, the carrier gas being selected from the group consisting of helium, argon, and nitrogen.
9. The method of claim 1 , wherein the tin-containing precursor is tetrakis(dimethylamino) tin, and the oxygen-containing precursor is oxygen, and the semiconductor substrate is exposed to tetrakis(dimethylamino) tin and oxygen.
10. The method of claim 1 , wherein the providing comprises:
providing the semiconductor substrate having a plurality of protruding features, the protruding features having horizontal surfaces and sidewalls;
exposing the semiconductor substrate to the tin-containing precursor and the oxygen-containing precursor to form the tin oxide layer on the horizontal surfaces and sidewalls of the protruding features; and
forming a passivation layer over the tin oxide layer at the sidewalls of the protruding features.
11. The method of claim 1 , wherein the carbon-containing material is photoresist, and wherein (b) comprises selectively etching the tin oxide in a presence of photoresist.
12. The method of claim 1 , wherein (b) comprises selectively etching the tin oxide in a presence of silicon (Si).
13. The method of claim 1 , wherein (b) comprises selectively etching the tin oxide in a presence of carbon (C).
14. The method of claim 1 , wherein tin oxide layer is provided using at least one of chemical vapor deposition process, atomic layer deposition, or any combination thereof.
15. The method of claim 14 , wherein tin oxide layer is provided using plasma-enhanced atomic layer deposition (PEALD).
16. The method of claim 1 , wherein method further comprises exposing the semiconductor substrate at a process parameter that maintains each of the tin-containing precursor and the oxygen-containing precursor independently in a gaseous phase.
17. The method of claim 16 , wherein the process parameter is a temperature of the process chamber that is between about 20° C. and about 500° C.
18. The method of claim 16 , wherein the process parameter is a flow rate at which each of the tin-containing precursor and the oxygen-containing precursor independently is flowed between about 10 sccm and about 10,000 sccm.
19. The method of claim 1 , wherein the semiconductor substrate is exposed to the tin-containing precursor having a formula
R x —Sn-A (4-x)
wherein x can be 0, 1, 2 or 3;
R can be selected from aliphatic, heteroaliphatic, or any combination thereof; and
A is YR′ z wherein Y can be selected from N or O;
z is 1 when Y is O, and z is 2 when Y is N; and
each R′ can be independently selected from aliphatic, heteroaliphatic, or any combination thereof.
20. The method of claim 19 , wherein a first R′ of YR′ z is same as a second R′ of YR′ z .
21. The method of claim 19 , wherein a first R′ of YR′ z is different from a second R′ of YR′ z .
22. The method of claim 21 , wherein the tin-containing precursor is tetrakis(ethylmethylamino) tin.
23. A method of processing a semiconductor substrate, the method comprising:
(a) providing a semiconductor substrate having an exposed layer of tin oxide;
(b) selectively etching the tin oxide in a presence of a material selected from the group consisting of silicon (Si), carbon (C), and a carbon-containing material with an etch selectivity of at least 10 by exposing the semiconductor substrate to a plasma formed in a process gas comprising H 2 and a hydrocarbon, such that a carbon-containing polymer is formed on the semiconductor substrate, wherein a ratio of H 2 to hydrocarbon in the process gas is at least 5.
24. The method of claim 23 , wherein the tin oxide is selectively etched in a presence of the carbon-containing material, and wherein the carbon-containing material is photoresist.
25. The method of claim 23 , wherein the carbon-containing material is photoresist, and wherein an etch selectivity for etching tin oxide in the presence of the photoresist is at least 100.
26. The method of claim 23 , wherein the semiconductor substrate provided in (a) comprises an exposed patterned layer of photoresist.
27. The method of claim 23 , wherein the hydrocarbon is methane (CH 4 ).
28. The method of claim 23 , wherein a ratio of H 2 to hydrocarbon in the process gas is at least 10.
29. The method of claim 23 , wherein the etching in (b) is conducted at a temperature of less than 100° C.
30. The method of claim 23 , wherein the process gas further comprises an inert gas.
31. The method of claim 23 , wherein (b) comprises selectively etching the tin oxide in a presence of silicon (Si).
32. The method of claim 23 , wherein (b) comprises selectively etching the tin oxide in a presence of carbon (C).