For thick plating applications like copper pillar bump processing in semiconductor advanced packaging, Shin-Etsu has introduced a positive tone, chemically amplified ultra thick photoresist, SIPR-7126. The photoresist was developed to plate high aspect ratio features, like those used in copper pillar processing, and GaAs and MEMS devices.
These special applications need an ultra thick layer of photoresist to help cover topography on the integrated circuit and to plate very high aspect ratio features. The plating chemistries are complex and varied so the resist must also be robust to the different plating environments.
Through-Silicon Vias (TSV)
SIPR-7126 is also applicable to semiconductor etch applications, like MEMS and through-silicon vias (TSVs), where process engineers must etch the entire thickness of silicon to build the device circuitry.
This flexible i-line photoresist can be developed by standard TMAH solutions; can be exposed by multiple exposure tools, such as steppers and aligners; and can plate up to 100 microns in a single coat with vertical profiles.
Ultra Thick Photoresist Features Include:
- excellent flexibility with different plating chemistries
- easy removal
- easy rework and,
- no post exposure bake needed.
The 7100 series has been in production for several years and the latest version, SIPR™-7126, has been optimized to reduce processing steps and improve removability. This new photoresist is available for sampling and evaluation by contacting Shin-Etsu MicroSi.