Method of etching semiconductor structures with etch gas
Disclosed are sulfur-containing compounds for plasma etching channel holes, gate trenches, staircase contacts, capacitor holes, contact holes, etc., in Si-containing layers on a substrate and plasma etching methods of using the same. The plasma etching compounds may provide improved selectivity between the Si-containing layers and mask material, less damage to channel region, a straight vertical profile, and reduced bowing in pattern high aspect ratio structures.
1. A method for plasma etching a silicon-containing layer on a substrate, the method comprising,
introducing a vapor of a compound into a chamber containing the silicon-containing layer on a substrate, the compound selected from the group consisting of:
C 2 F 4 S 2 (CAS 1717-50-6), F 3 CSH (CAS 1493-15-8), F 3 C—CF 2 —SH (CAS 1540-78-9), F 3 C—CH 2 —SH (CAS 1544-53-2 CHF 2 —CF 2 —SH 812-10-2 CF 3 —CF 2 —CH 2 —SH (CAS 677-57-6), F 3 C—CH(SH)—CF 3 (CAS 1540-06-3), F 3 C—S—CF 3 (CAS 371-78-8), F 3 C—S—CHF 2 (CAS 371-72-2), F 3 C—CF 2 —S—CF 2 —CF 3 (CAS 155953-22-3), F 3 C—CF 2 —CF 2 —S—CF 2 —CF 2 —CF 3 (CAS 356-63-8), c(-S—CF 2 —CF 2 —CHF—CF 2 —) (CAS 1035804-79-5), c(-S—CF 2 —CHF—CHF—CF 2 —) (CAS 30835-84-8), c(-S—CF 2 —CF 2 —CF 2 —CF 2 —CF 2 —) (CAS 24345-52-6), c(-S—CFH—CF 2 —CF 2 —CFH—)(2 R, 5 R) (CAS 1507363-75-8), c(-S—CFH—CF 2 —CF 2 —CFH—)(2 R, 5 S) (CAS 1507363-76-9), and c(-S—CFH—CF 2 —CF 2 —CH 2 —) (CAS 1507363-77-0);
introducing an inert gas into the chamber;
generating a plasma to produce an activated vapor from the vapor; and
removing volatile by-product from the chamber, wherein the activated vapor selectively reacts with the silicon-containing layer to form the volatile by-product.
2. The method of claim 1 , wherein the compound is C 2 F 4 S 2 (CAS 1717-50-6).
3. The method of claim 1 , wherein the compound is selected from the group consisting of F 3 CSH (CAS 1493-15-8), F 3 C—CF 2 —SH (CAS 1540-78-9), F 3 C—CH 2 —SH (CAS 1544-53-2), CHF 2 —CF 2 —SH (812-10-2), CF 3 —CF 2 —CH 2 —SH (CAS 677-57-6), and F 3 C—CH(SH)—CF 3 (CAS 1540-06-3).
4. The method of claim 1 , wherein the compound is selected from the group consisting of F 3 C—S—CF 3 (CAS 371-78-8), F 3 C—S—CHF 2 (CAS 371-72-2), F 3 C—CF 2 —S—CF 2 —CF 3 (CAS 155953-22-3), and F 3 C—CF 2 —CF 2 —S—CF 2 —CF 2 —CF 3 (CAS 356-63-8).
5. The method of claim 1 , wherein the compound is selected from the group consisting of c(-S—CF 2 —CF 2 —CHF—CF 2 —) (CAS 1035804-79-5), c(-S—CF 2 —CHF—CHF—CF 2 —) (CAS 30835-84-8), c(-S—CF 2 —CF 2 —CF 2 —CF 2 —CF 2 —) (CAS 24345-52-6), c(-S—CFH—CF 2 —CF 2 —CFH—)(2 R, 5 R) (CAS 1507363-75-8), c(-S—CFH—CF 2 —CF 2 —CFH—) (2 R, 5 S) (CAS 1507363-76-9), and c(-S—CFH—CF 2 —CF 2 —CH 2 —) (CAS 1507363-77-0).
6. The method of claim 1 , wherein the silicon-containing layer comprises a layer of silicon oxide, silicon nitride, polysilicon, or combinations thereof.
7. The method of claim 1 , further comprising introducing an oxidizer into the chamber.
8. The method of claim 7 , wherein the oxidizer is selected from the group consisting of O 2 , O 3 , CO, CO 2 , NO, N 2 O, NO 2 , and combinations thereof.
9. The method of claim 7 , wherein the oxidizer is O 2 .
10. The method of claim 1 , further comprising introducing an etching gas into the chamber, wherein the etching gas is selected from the group consisting of cC 5 F 8 , cC 4 F 8 , C 4 F 8 , C 4 F 6 , CF 4 , CH 3 F, CF 3 H, CH 2 F 2 , COS, CS 2 ; CF 3 I; C 2 F 3 I; C 2 F 5 I; SO 2 ; trans-1,1,1,4,4,4-hexafluoro-2-butene; cis-1,1,1,4,4,4-hexafluoro-2-butene; hexafluoroisobutene; hexafluorocyclobutane (trans-1,1,2,2,3,4); pentafluorocyclobutane (1,1,2,2,3-); tetrafluorocyclobutane (1,1,2,2-); and hexafluorocyclobutane (cis-1,1,2,2,3,4).
11. The method of claim 1 , wherein the compound is F 3 C—CH 2 —SH (CAS 1544-53-2).
12. The method of claim 1 , wherein the silicon-containing layer comprises a combination of silicon oxide and silicon nitride.
13. The method of claim 12 , wherein the compound is F 3 C—CH 2 —SH (CAS 1544-53-2).
14. The method of claim 12 , wherein the compound is C 2 F 4 S 2 (CAS 1717-50-6).
15. A method for plasma etching a silicon-containing layer, the method comprising,
introducing F 3 C—CH 2 —SH (CAS 1544-53-2) gas into a chamber containing the silicon-containing layer on a substrate, wherein the silicon-containing layer comprises a combination of silicon oxide and silicon nitride;
introducing an inert gas into the chamber;
plasma activating F 3 C—CH 2 —SH (CAS 1544-53-2) gas; and
removing volatile by-product from the chamber, wherein the plasma activated F 3 C—CH 2 —SH (CAS 1544-53-2) gas selectively reacts with the silicon-containing layer to form the volatile by-product.