Quantitative evaluation of residual resist in electron beam lithography based on scanning electron microscopy imaging...

Area of Science:

• Nanotechnology and Materials Science
• Advanced Lithography Techniques
• Surface Chemistry and Characterization

Background:

• Electron beam lithography (EBL) is crucial for high-precision nanoscale patterning.
• Resist residues in EBL structures hinder subsequent processes like etching and lift-off.
• Current residue evaluation relies on qualitative scanning electron microscopy (SEM) analysis, leading to inefficient optimization.

Purpose of the Study:

• To develop a quantitative method for evaluating resist residues in EBL.
• To establish a predictive model for optimal exposure dose based on residue quantification.
• To enhance the efficiency and reduce the cost of nanoscale fabrication processes.

Main Methods:

• Utilized threshold segmentation algorithms on SEM images to differentiate resist structures and residues.
• Quantified residues by analyzing grayscale values and their ratios within segmented regions.
• Developed a residue amount vs. exposure dose curve for predicting optimal parameters.

Main Results:

• Successfully quantified resist residues in hydrogen silsesquioxane (HSQ) structures with 30 nm linewidth.
• Predicted an optimal exposure dose of 1800 µC cm⁻² for HSQ, validated experimentally.
• Demonstrated the method's general applicability on polymethyl methacrylate (PMMA) and ZEP-520A resist materials.

Conclusions:

• The proposed quantitative method offers an accurate and efficient alternative to qualitative residue assessment in EBL.
• This approach significantly reduces experimental costs and iteration cycles in nanoscale fabrication.
• The method holds potential for improving yield and production efficiency in advanced nano-manufacturing.