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Surface Analysis of Photolithographic Patterns using ToF-SIMS and PCA
Manish Dubey1, Kazunori Emoto, Fang Cheng
1National ESCA and Surface Analysis Center for Biomedical Problems, Box 351750, University of Washington, Seattle, WA 98195-1750 USA.
Surface and Interface Analysis : SIA
|September 17, 2009
Summary
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) coupled with principal component analysis (PCA) effectively mapped residual photoresist on patterned surfaces. This technique offers high-resolution surface analysis for quality control in photolithography.
Area of Science:
- Surface Science
- Analytical Chemistry
- Materials Science
Background:
- Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a sensitive surface analysis technique.
- Imaging ToF-SIMS generates 2-D and 3-D surface reactivity maps.
- Principal component analysis (PCA) enhances chemical differentiation in complex datasets.
Purpose of the Study:
- To apply ToF-SIMS and PCA for analyzing patterned surfaces used in bioassays and biosensors.
- To identify and spatially map residual photoresist material after photolithographic processing.
- To evaluate the effectiveness of ToF-SIMS/PCA for surface quality control in microfabrication.
Main Methods:
- Co-patterning of N-hydroxysuccinimide (NHS) and 2-methoxyethylamine (MeO) on a polymer coating.
- Utilizing standard photolithography for pattern development, including photoresist deposition and removal.
- Applying ToF-SIMS for high-resolution surface imaging and elemental/chemical analysis.
- Employing PCA for multivariate analysis of ToF-SIMS data to differentiate chemical regions.
Main Results:
- Significant residual photoresist detected at the interface of NHS/MeO patterned regions.
- Lower concentrations of residual photoresist identified within MeO-containing regions.
- ToF-SIMS/PCA provided detailed spatial mapping of residues, surpassing other characterization methods.
Conclusions:
- ToF-SIMS coupled with PCA is a powerful, high-resolution tool for detecting surface photoresist residues.
- This method offers high sensitivity and specificity crucial for surface quality control after photolithography.
- The findings are relevant for optimizing photolithographic processes across various material applications.
