Nanoscale Phase Change Material Array by Sub-Resolution Assist Feature for Storage Class Memory Application.

Area of Science:

• Materials Science
• Semiconductor Device Fabrication
• Nanotechnology

Background:

• High-density phase change memory (PCM) arrays demand minimized critical dimensions (CD) and maximized process windows for phase change materials.
• Achieving uniform nanoscale patterning of chalcogenides is difficult due to optical proximity effect (OPE) in lithography and micro-loading effect in etching.

Purpose of the Study:

• To demonstrate a method for fabricating high-density phase change material arrays with half-pitch down to 70 nm.
• To co-optimize lithography and plasma etching processes for improved uniformity and reliability.

Main Methods:

• Utilized immersion lithography with sub-resolution assist features (SRAF) to mitigate OPE-induced linewidth shrinkage.
• Employed focused-energy matrix and optimized plasma etching parameters to suppress micro-loading effects and etching damage.

Main Results:

• Successfully fabricated phase change material arrays with half-pitch down to approximately 70 nm.
• Demonstrated improved line survival at array edges and uniform etching profiles across patterns.
• Significantly suppressed micro-loading effects and plasma etching damage.

Conclusions:

• The co-optimization of lithography and plasma etching enables the fabrication of high-density phase change material arrays.
• This approach enhances uniformity and reliability, paving the way for advanced mass storage applications.