Donald G. Larson

Reliability studies of 1-kHz KrF excimer lasers for DUV lithography

Chip makers are gearing up for 686-class micro-processors and 64 Mb production. These require producing < 0.30 micrometers critical features. They are also focusing on 256 Mb DRAMs that require below 0.25 micrometers design rules. Therefore, the shift from mercury lamp based i-line to 248 nm Deep-Ultra- Violet (DUV) steppers has begun in earnest. Current KrF laser models from several suppliers satisfy the optical requirements necessary for pilot production. However, as the move from DUV lithography R&D environment to production occurs, the lasers manufacturability, uptime requirements and cost-of-operation (CoO) become more demanding. The chip maker requires reliability, availability and maintainability data from laser manufacturers to support uptime and CoO estimates. Often, such data are required long before the lasers actually go into production.