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Relating Photoresist Etch Characteristics to Langmuir Probe Measurements in an Electron Cyclotron Resonance Source

Published online by Cambridge University Press:  22 February 2011

K. T. Sung
Affiliation:
Department of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor, MI 48109-2122
W. H. Juan
Affiliation:
Department of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor, MI 48109-2122
S. W. Pang
Affiliation:
Department of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor, MI 48109-2122
M. Dahimene
Affiliation:
Wavemat Inc., Plymouth, MI 48170
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Abstract

In this work, Langmuir probe measurements were used to characterize a multipolar electron cyclotron resonance (ECR) plasma source. This system has many controllable parameters including microwave power, rf power, gas, pressure, flow rate, and source distance. Both double and triple Langmuir probes were used for the plasma characterization. The results from the Langmuir probe measurements were correlated to the etch characteristics of photoresist. Ion density and photoresist etch rate were found to increase with microwave power but decrease with source distance. However, rf power does not have significant influence on ion density although the photoresist etch rate increases substantially with if power. Ion density first increases then decreases at higher pressure. Maximum ion density occurs at lower pressure for larger distance below the ECR source. Ion density uniformity for an O2 plasma is ±2% across a 16 cm diameter region at 23 cm below the source. For photoresist etched at 10 cm source distance, etch rate uniformity is ±2% for a 15 cm diameter wafer. The results from the Langmuir probe measurements indicate that photoresist etching is enhanced by ion density and ion energy.

Type
Research Article
Copyright
Copyright © Materials Research Society 1994

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