Photoresist latent and developer images as probed by neutron reflectivity methods

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Manufacturing

Background:

• Photoresist materials are essential for fabricating integrated circuits with decreasing feature sizes.
• Extreme ultraviolet (EUV) lithography, using 13.5 nm wavelength, demands high image fidelity from photoresists.
• Current polymer photoresists may be approaching resolution limits, necessitating advanced characterization techniques.

Purpose of the Study:

• To investigate the chemical and physical structure of chemically amplified photoresists at the nanometer scale (1-100 nm) at lithographic feature edges.
• To understand the interactions between photoresist components, photoacids, and developers and their impact on feature fidelity.
• To provide insights for designing next-generation photoresists for EUV photolithography.

Main Methods:

• Utilized neutron reflectivity measurements to profile the nanometer-scale composition of the chemical latent image at lithographic line-edges.
• Examined four generations of advanced photoresist formulations over seven years.
• Separated optical resolution effects from materials processing effects through in situ interface measurements.

Main Results:

• Neutron reflectivity provided detailed nanometer-scale composition profiling of the chemical latent image.
• Quantified the impact of photoresist/photoacid and photoresist/developer interactions on lithographic feature fidelity.
• Established physical relationships between resist structure, processing, and feature fidelity.

Conclusions:

• Advanced photoresist formulations and processing significantly influence lithographic feature fidelity.
• Neutron reflectivity is a key technique for understanding nanometer-scale resist behavior.
• Findings inform the development of novel resist architectures for next-generation EUV lithography.