US 12,438,005 B2
Low temperature selective etching of silicon nitride using microwave plasma
Thai Cheng Chua, Cupertino, CA (US); Christian Valencia, Alhambra, CA (US); Doreen Yong, Singapore (SG); Tuck Foong Koh, Singapore (SG); Jenn-Yue Wang, Fremont, CA (US); and Philip Allan Kraus, San Jose, CA (US)
Assigned to Applied Materials, Inc., Santa Clara, CA (US)
Filed by Applied Materials, Inc., Santa Clara, CA (US)
Filed on Sep. 6, 2022, as Appl. No. 17/903,913.
Claims priority of provisional application 63/253,487, filed on Oct. 7, 2021.
Prior Publication US 2023/0109912 A1, Apr. 13, 2023
Int. Cl. H01L 21/311 (2006.01)
CPC H01L 21/31116 (2013.01) 19 Claims
OG exemplary drawing
 
1. A method of etching a 3D structure, comprising:
providing the 3D structure in a microwave plasma chamber, wherein the 3D structure comprises:
a substrate; and
alternating layers of silicon oxide and silicon nitride over the substrate;
flowing a first gas into the microwave plasma chamber, wherein the first gas comprises sulfur and fluorine;
flowing a second gas into the microwave plasma chamber, wherein the second gas comprises an inert gas, and wherein a ratio of the first gas to the second gas is 0.4 or smaller;
flowing a third gas into the microwave plasma chamber, wherein the third gas comprises dichloro-silane (DCS), and wherein an amount of DCS is less than an amount of the first gas;
striking a plasma in the microwave plasma chamber; and
etching the silicon nitride, wherein an etching selectivity of silicon nitride to silicon oxide is 50:1 or greater.