Removal of post-etch 193 nm photoresist in porous low-k dielectric patterning using UV irradiation and ozonated water

All-wet processes are gaining a renewed interest for the removal of post-etch photoresist (PR) in the back-end-of-line (BEOL) semiconductor manufacturing. However, degradation of DUV–PR by etch plasmas results in a modified top layer of the PR that is cross-linked (so-called crust) and therefore not soluble anymore using pure organic solvents. This study investigates the modification of 193 nm post-etch PR by UV irradiation with different wavelengths. UV irradiation showed to be an interesting process to increase CC bond concentration in post-etch PR, which was used as an intermediate step to enhance PR wet strip using ozonated DI water. Treatment of post-etch PR by 222 or 283 nm led to the largest increase in CC bonds. The combination of UV with ozonated DI water is a promising process sequence for PR and BARC strip in BEOL applications.