Photolithography (Litho) is the process of projecting a microscopic pattern, of the desired circuitry, onto a wafer. The process involves multiple steps:
- Coating the wafer with light-sensitive photoresist film
- Exposing the film using a mask with the desired circuit pattern
- Developing the photoresist film to leave behind the required pattern on the wafer
Immersion lithography and multi-patterning are key enablers as the semiconductor industry moves towards smaller critical dimension (CD) geometries. Metrology requirements for these advanced technologies are driven by Litho process challenges such as photoresist shrinkage and tighter CD uniformity (CDU).
Traditional metrology methods like CD-SEM are unable to meet the required sampling throughput and may damage the resist material. As a result, semiconductor manufacturers are looking for metrology solutions to provide the speed and accuracy in the Litho process control.
Nova’s scatterometry solutions deliver accurate measurements of key photolithography features, including high resolution & precision of the resist profile CD and sidewall angle. The non-destructive measurement technique provides tight process control for advanced Litho processes.
Nova’s metrology solutions are renowned for delivering the industry’s leading throughput. The high-throughput solution delivers CDU sampling in feedback and feed-forward modes to improve process control.
For example – better control over multi-patterning can be achieved with post-litho, resist profile measurements feedback to the litho cell for lot-to-lot control. Feed-forward measurements to the etch process provide the required resist-trimming information for wafer-to-wafer control.