Polysilicon gate etching in high density plasmas. V. Comparison between quantitative chemical analysis of photoresist and oxide masked polysilicon gates etched in HBr/Cl2/O2plasmas
作者:
F. H. Bell,
O. Joubert,
期刊:
Journal of Vacuum Science&Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena
(AIP Available online 1997)
卷期:
Volume 15,
issue 1
页码: 88-97
ISSN:1071-1023
年代: 1997
DOI:10.1116/1.589259
出版商: American Vacuum Society
关键词: PLASMA;ETCHING;SILICON;PHOTOELECTRON SPECTROSCOPY;POLYMERS;ELECTROSTATICS;QUANTITATIVE CHEMICAL ANALYSIS;CHLORINE;BROMINE;Si;resists
数据来源: AIP
摘要:
We have used x-ray photoelectron spectroscopy (XPS) to study the chemical constituents present on the surfaces after etching of poly-Si features masked with photoresist or oxide patterns. The wafers were etched in a low pressure, high density plasma, helicon source using a HBr/Cl2/O2gas mixture. The O2gas flow rate was tuned to obtain anisotropic etching profiles by forming an SiO2like layer on the sidewalls of the features and maximizing the polysilicon/gate oxide selectivity. Electrostatic charging of insulating surfaces and geometric shadowing of photoelectrons by adjacent photoresist lines were performed to differentiate the photoemission signals from the tops, sidewalls, and bottoms of the features. XPS analyses have shown that the passivation layer formed on the polysilicon sidewalls during etching is a chlorine rich silicon oxide film with both type of masks. This film contains a low carbon concentration when resist is used as a mask. The similar thickness and constitution of the sidewall for oxide and photoresist masked poly-Si samples indicate that the nature of the mask material has no significant effect on the sidewall passivation mechanism.
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