Etching method using oxygen-containing hydrofluorocarbon
An etching method for forming a high aspect ratio aperture by selectively etching one or more silicon-containing films in a substrate using a patterned mask layer deposited on top of the one or more silicon-containing films comprises: mounting the substrate in a processing chamber; introducing an etching gas containing a vapor of an oxygen-containing hydrofluorocarbon into the processing chamber; converting the etching gas to a plasma; and allowing an etching reaction to proceed between the plasma and the one or more silicon-containing films so that the one or more silicon-containing films are selectively etched versus the patterned mask layer to form the high aspect ratio aperture, wherein the oxygen-containing hydrofluorocarbon has a general formula C x H y F z O n , where 2≤x≤13, 1≤y≤15, 1≤z≤21, 1≤n≤3.
1 . An etching method for forming a high aspect ratio aperture by selectively etching one or more silicon-containing films in a substrate using a patterned mask layer deposited on top of the one or more silicon-containing films, the method comprising:
mounting the substrate in a processing chamber;
introducing an etching gas containing a vapor of an oxygen-containing hydrofluorocarbon into the processing chamber;
converting the etching gas to a plasma; and
allowing an etching reaction to proceed between the plasma and the one or more silicon-containing films so that the one or more silicon-containing films are selectively etched versus the patterned mask layer to form the high aspect ratio aperture,
wherein the oxygen-containing hydrofluorocarbon has a general formula C x H y F z O n , where 2≤x≤13, 1≤y≤15, 1≤z≤21, 1≤n≤3, provided that when x=4, y≠3, z≠7, n≠1,
wherein the oxygen-containing hydrofluorocarbon has at least one ether group represented by one of following formulas:
R 1 —CO—O—CH 2 —R 1 ,
R 2 —CH 2 —O—CH 2 —R 2 or
R 3 —CHF—O—CF 2 —R 1 ,
wherein R 1 is H, F, C x H 2x+2-z F z or C x F 2x+2 ; R 2 is H, C x H 2x+2-z F z or C x F 2x+2 ; R 3 is F, C x H 2x+2-z F z or C x F 2x+2 , where 2≤x≤3 and 1≤z≤3.
2 . The method of claim 1 , wherein the oxygen-containing hydrofluorocarbon contains at least one oxygen atom in an ether group or in a carbonyl group.
3 . The method of claim 1 , wherein the oxygen-containing hydrofluorocarbon is selected from C 4 H 2 F 6 O 2 , C 3 H 2 F 6 O, C 2 H 2 F 4 O, C 2 HF 3 O, C 3 H 5 F 3 O, C 2 H 4 F 2 O, C 5 H 4 F 8 O, C 5 HF 11 O, C 2 H 3 F 3 O, or their isomers.
4 . The method of claim 1 , wherein the oxygen-containing hydrofluorocarbon is C 4 H 2 F 6 O 2 or its isomers.
5 . The method of claim 1 , wherein the oxygen-containing hydrofluorocarbon is C 4 H 2 F 6 O 2 , CAS No. 407-38-5.
6 . The method of claim 1 , wherein the etching gas further includes a vapor of a fluorocarbon or hydrofluorocarbon selected from CF 4 , C 2 F 6 , C 3 F 6 , C 4 F 6 , C 4 F 8 , C 5 F 8 , C 5 F 10 , C 6 F 12 , C 7 F 14 , C 8 F 16 , CH 2 F 2 , CH 3 F, CHF 3 , C 5 HF 7 , C 3 H 2 F 6 , C 3 H 4 F 2 , C 3 F 2 H 4 , C 4 H 2 F 6 , C 4 H 3 F 7 , C 3 HF 4 N, CF 3 I, C 3 F 7 I, C 4 F 9 I, C 4 H 9 F 3 Si, C 5 H 9 F 5 Si or combinations thereof.
7 . The method of claim 1 , wherein the etching gas further includes an oxidizing gas selected from O 2 , O 3 , CO, CO 2 , SO, SO 2 , FNO, N 2 , NO, N 2 O, NO 2 , H 2 O, COS or combinations thereof.
8 . The method of claim 1 , wherein the etching gas further includes an inert gas selected from He, Ar, Xe, Kr or Ne.
9 . The method of claim 1 , wherein the etching gas further includes an additional gas selected from H 2 , SF 6 , NF 3 , N 2 , NH 3 , Cl 2 , BCl 3 , Br 2 , F 2 , HBr, HCl, PF 3 or combinations thereof.
10 . The method of claim 1 , wherein an aspect ratio of the high aspect ratio aperture is above 5.
11 . The method of claim 1 , wherein the one or more silicon-containing films comprise a layer of Si a O b H c C d N e , where a>0, b, c, d and e≥0, selected from silicon oxide, silicon nitride, crystalline Si, poly-silicon, polycrystalline silicon, amorphous silicon, low-k SiCOH, SiOCN, SiC, SiON, or a layer of alternating silicon oxide and silicon nitride (ONON) films or alternating silicon oxide and poly-silicon (OPOP) films.
12 . The method of claim 11 , wherein a selectivity of the silicon oxide film versus the silicon nitride film in the layer of ONON films ranges from 1:2 to 2:1.
13 . An etching method for forming a high aspect ratio aperture by selectively etching a silicon oxide film in a substrate using a patterned mask layer deposited on top of the silicon oxide film, the method comprising:
mounting the substrate in a processing chamber;
introducing an etching gas containing an oxygen-containing hydrofluorocarbon C 4 H 4 F 6 O or C 4 H 2 F 6 O 2 vapor into the processing chamber;
converting the etching gas to a plasma; and
allowing an etching reaction to proceed between the plasma and the silicon oxide film so that the silicon oxide film is selectively etched versus the patterned mask layer to form the high aspect ratio aperture.
14 . The method of claim 13 , wherein the oxygen-containing hydrofluorocarbon is C 4 H 2 F 6 O 2 , CAS 407-38-5.
15 . The method of claim 13 , wherein the etching gas further includes a vapor of a fluorocarbon or hydrofluorocarbon selected from CF 4 , C 2 F 6 , C 3 F 6 , C 4 F 6 , C 4 F 8 , C 5 F 8 , C 5 F 10 , C 6 F 12 , C 7 F 14 , C 8 F 16 , CH 2 F 2 , CH 3 F, CHF 3 , C 5 HF 7 , C 3 H 2 F 6 , C 3 H 4 F 2 , C 3 F 2 H 4 , C 4 H 2 F 6 , C 4 H 3 F 7 , C 3 HF 4 N, CF 3 I, C 3 F 7 I, C 4 F 9 I, C 4 H 9 F 3 Si, C 5 H 9 F 5 Si or combinations thereof.
16 . The method of claim 13 , wherein the etching gas further includes an oxidizing gas selected from O 2 , O 3 , CO, CO 2 , SO, SO 2 , FNO, N 2 , NO, N 2 O, NO 2 , H 2 O, COS or combinations thereof.
17 . The method of claim 13 , wherein the etching gas further includes an inert gas selected from He, Ar, Xe, Kr or Ne.
18 . The method of claim 13 , wherein the etching gas further includes an additional gas selected from H 2 , SF 6 , NF 3 , N 2 , NH 3 , Cl 2 , BCl 3 , Br 2 , F 2 , HBr, HCl, PF 3 or combinations thereof.
19 . The method of claim 13 , wherein an aspect ratio of the high aspect ratio aperture is above 5.