RLS trade-off to remain a challenge
Dongjin Semichem has successfully reduced the sensitivity of its photoresist (PR) for extreme ultraviolet (EUV) processes in chip production.
Research into EUV PR in recent times is focused on improving throughput, Dongjin Semichem manager Kim Jeong-shik told an audience during SEMI SMC Korea 2023 industry conference held at Suwon on Friday.
Throughput improvement can lead to chipmakers reducing their spending on EUV equipment and fab equipment so there are increasing calls by customers for this, Kim said.
Dongjin Semichem, following these requests, has improved the RLS (resolution, linewidth roughness, and sensitivity) of its PR; in sensitivity, it reduced it by half to between 40mJ/cm² to 50mJ/cm² from 80mJ/cm² of 2020.
PR is used in the lithography process in chip production. It reacts to light to have chemical reactions and is used to put in the circuit pattern on the wafer.
Improved PR sensitivity can allow chipmakers to process more wafers per hour, which saves chipmakers money.
This is critical for PR used in EUV as EUV equipment costs between 150 billion won to 200 billion won per unit. High-NA EUV equipment that will start shipping in 2024 is expected to cost 400 billion won.
Currently, besides Dongjin Semichem, JSR, Shin-Etsu Chemical and Tokyo Ohka Kogyo produce EUV PR.
Increasing the sensitivity of EUV PR is difficult as there are trade-offs between the RLS. This is why inorganic PR is also expected to be developed by companies. Inorganic PR can maximize the use of photons that can offset the RLS trade-off.