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Study on the influence of electron angular distribution on mask pattern damage in plasma etching
Author(s) -
Zhang Peng,
Zhang Lidan,
Xu Lan
Publication year - 2020
Publication title -
plasma processes and polymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 74
eISSN - 1612-8869
pISSN - 1612-8850
DOI - 10.1002/ppap.202000014
Subject(s) - etching (microfabrication) , materials science , electron , plasma etching , plasma , substrate (aquarium) , reactive ion etching , isotropy , trench , electric field , isotropic etching , enhanced data rates for gsm evolution , optics , ion , optoelectronics , nanotechnology , chemistry , physics , layer (electronics) , engineering , telecommunications , oceanography , organic chemistry , quantum mechanics , geology
Abstract The perfect pattern transfer from mask to substrate during the plasma‐etching process is strongly limited by the charging effect on the mask surface, which is increased by the accumulation of negative charges on the surface. These are mainly caused by high‐velocity isotropic electrons impinging on the mask surface faster than ions. These anisotropic ions thus bombard the undesired locations of the mask under the influence of the electric field ( E ‐field) established by electrons. This problem leads to significant damages to the mask pattern and causes deformations of etched features due to failure pattern transfer. This study examined that electron angular distribution (EAD; relative to the vertical direction, which can be regulated by voltage waveform tailoring) displays a close relationship with the mask pattern damage. Based on a modeling framework that consists of a surface etching module, a surface charging module, and a profile evolution module, the effects of changing the EAD on distributions of spatial E ‐field and etching rate were studied focusing on an isolated rough mask hole surface. It is revealed that by narrowing the EAD shape, the E ‐field strength and the etching rate around the mask hole edge can be reduced strongly, meanwhile, the number of electrons penetrating into the bottom of the trench can be greatly increased. These developments will supposedly reduce the mask‐pattern damage and improve the etching of high‐aspect‐ratio (HAR) features into the substrate. The simulated evolution rates of profile of a rough mask hole and the profile of E ‐field strength inside the hole under various EAD shapes verify the above conclusions. The mechanism behind these results was analyzed systematically. This study provides a significant point for further investigation into the optimization of the etching technique.