US 11,817,312 B2
Delayed pulsing for plasma processing of wafers
Akhil Mehrotra, Sunnyvale, CA (US); Vinay Shankar Vidyarthi, San Jose, CA (US); Daksh Agarwal, Sunnyvale, CA (US); Samaneh Sadighi, San Jose, CA (US); Jason Kenney, Santa Clara, CA (US); and Rajinder Dhindsa, Pleasanton, CA (US)
Assigned to APPLIED MATERIALS, INC., Santa Clara, CA (US)
Filed by APPLIED MATERIALS, INC., Santa Clara, CA (US)
Filed on Oct. 29, 2018, as Appl. No. 16/173,988.
Prior Publication US 2020/0135458 A1, Apr. 30, 2020
Int. Cl. H01L 21/02 (2006.01); H01L 21/3065 (2006.01); H01J 37/32 (2006.01); H01L 21/67 (2006.01); H01L 21/66 (2006.01); H01L 21/308 (2006.01)
CPC H01L 21/02274 (2013.01) [H01J 37/32146 (2013.01); H01L 21/0228 (2013.01); H01L 21/308 (2013.01); H01L 21/3065 (2013.01); H01L 21/67069 (2013.01); H01L 22/26 (2013.01)] 13 Claims
OG exemplary drawing
 
1. A method in a plasma chamber system for processing a wafer, comprising:
generating a plasma by applying RF source power to a plasma generating element of the plasma chamber for a first period of time of a pulse period of the RF source power;
after an expiration of the first period of time, removing the RF source power from the plasma generating element;
providing a delay after the removal of the RF source power and before an application of an RF bias signal;
controlling a length of the delay between the removal of the RF source power and the application of an RF bias signal to control a neutral density to ion density ratio for the plasma for determining a desired etch rate, etch depth, or etch selectivity for features on a surface of the wafer;
after the delay is controlled, applying an RF bias signal to bias the generated plasma towards the wafer for a second period of time during the pulse period of the RF source power; and
after an expiration of the second period of time, removing the RF bias signal before a next pulse period of the RF source power.