Chemically amplified soft-x-ray resists: sensitivity, resolution, and molecular photodesorption

Area of Science:

• Materials Science
• Nanotechnology
• Photolithography

Background:

• Chemically amplified resists (CARs) are crucial for high-resolution patterning.
• Novolac-based resists are widely used in microelectronics fabrication.
• Soft X-ray lithography offers potential for sub-wavelength patterning.

Purpose of the Study:

• To evaluate the lithographic performance of novolac-based CARs at 140 Å.
• To investigate ion photodesorption characteristics of these resists.
• To assess their suitability for soft X-ray projection imaging.

Main Methods:

• Flood exposure of resists AZ PF514, AZ PN114, and SAL 601.
• Time-of-flight mass spectrometry for ion photodesorption analysis.
• Soft X-ray projection imaging using a Schwarzschild objective and Ge/Si mask.

Main Results:

• Sensitivity (D(0.9)) values of 2.5-3.5 mJ/cm(2) for 0.25-µm films.
• Contrast values ranged from 3 (AZ PN114) to 5 (SAL 601).
• Ion desorption yields from AZ PN114 were approximately 90 times lower than PMMA.

Conclusions:

• Novolac-based CARs demonstrate promising sensitivity and contrast for 140 Å lithography.
• Reduced ion photodesorption enhances resist stability and process control.
• These resists are viable candidates for advanced soft X-ray lithography applications.