Self-Anchored Catalyst Interface Enables Ordered Via Array Formation from Submicrometer to Millimeter Scale for...

Area of Science:

• Materials Science and Engineering
• Nanotechnology
• Semiconductor Processing

Background:

• Metal-assisted chemical etching (MacEtch) is a solution-based, damage-free semiconductor etching method.
• Traditional MacEtch faces challenges with etching polycrystalline silicon (poly-Si) and controlling uniformity over larger feature sizes.
• Interface control between catalyst and semiconductor is critical for directional etching.

Purpose of the Study:

• To introduce a novel self-anchored catalyst (SAC) MacEtch method.
• To address limitations in directional control and etch rate for MacEtch.
• To enable fabrication of complex 3D semiconductor structures and vias.

Main Methods:

• Utilized a nanoporous catalyst film in the SAC-MacEtch approach.
• Nanoporous catalyst produces nanowires that physically anchor the film, ensuring directional etching.
• Studied etch rates as a function of porous catalyst diameter and applied to poly-Si/SiO2 multistacks.

Main Results:

• SAC-MacEtch confines etching direction and enhances etch rates due to increased liquid access.
• Significantly delayed mass-transport-limited critical diameter compared to nonporous catalysts.
• Successfully fabricated vias in poly-Si/SiO2 multistacks and large through-Si-via (TSV) arrays in thick silicon.

Conclusions:

• SAC-MacEtch offers superior control and efficiency for semiconductor etching.
• The method enables fabrication of high-aspect-ratio structures through challenging material stacks.
• This technique has significant implications for advanced 2.5D/3D photonic and electronic device applications.