Invited) Plasma Etching Technology Challenges for Future CMOS Fabrication Based on Microwave ECR Plasma

The dimensions of semiconductor devices are shrinking towards the nanometer range. More accurate surface reaction control is thus required in plasma etching on this scale. Time modulation (TM) of the radio-frequency (RF) bias, discharge, and gas injection processes has been investigated to improve both directional profiles and etch selectivity. Microwave electron cyclotron resonance (ECR) plasma was also shown to have affinities to pulse modulation and low ion energy processing. As examples, wiggling was improved using a pulsed discharge in a directed self-assembling (DSA) mask etch, and directionality was improved using gas pulsing technology in fin etching. In future MOS device fabrication, higher etch selectivity and more directional etch profiles are expected to be required and their accuracy requirements will reach the atomic level. A combination of pulsing technology (tri-time modulation, Tri-TM) and low bias power control at low pressure condition is considered as candidate technology for future device fabrication.