US 11,942,307 B2
Plasma processing with radio frequency (RF) source and bias signal waveforms
Zhiying Chen, Austin, TX (US); Barton Lane, Tokyo (JP); Yun Han, Albany, NY (US); Peter Lowell George Ventzek, Austin, TX (US); and Alok Ranjan, Austin, TX (US)
Assigned to Tokyo Electron Limited, Tokyo (JP)
Filed by Tokyo Electron Limited, Tokyo (JP)
Filed on Oct. 15, 2021, as Appl. No. 17/451,094.
Prior Publication US 2023/0117812 A1, Apr. 20, 2023
Int. Cl. H01J 37/32 (2006.01)
CPC H01J 37/32174 (2013.01) [H01J 2237/3341 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A method for plasma processing comprising:
sustaining a plasma in a plasma processing chamber, the plasma processing chamber comprising a first radio frequency (RF) electrode and a second RF electrode, wherein sustaining the plasma comprises:
coupling an RF signal source to the first RF electrode; and
applying a bias signal between the first RF electrode and the second RF electrode, the bias signal having a bipolar DC (B-DC) waveform comprising a plurality of B-DC pulses, each of the B-DC pulses comprising:
a negative bias duration during which the pulse has negative polarity relative to a reference potential,
a positive bias duration during which the pulse has positive polarity relative to the reference potential, and
a neutral bias duration during which the pulse has neutral polarity relative to the reference potential, wherein the bias signal has a B-DC-burst waveform comprising a train of B-DC-burst pulses, wherein each of the B-DC-burst pulses has a plurality of consecutive B-DC pulses that is present during a B-DC-burst duration followed by a B-DC-burst separation time during which there is no bias signal, a sum of the B-DC-burst duration and the B-DC-burst separation time being defined as a burst period.