Equipment design and process control of critical dimensions in lithography

The lithography sequence is the most critical step in the fabrication of nanostructures for integrated circuit manufacturing. In this paper, we present the development of in-situ real-time sensors and actuating sytems for real-time monitoring and control of the single most critical parameter in the lithography sequence: the critical dimension (CD) or linewidth of the structures. The use of an in-situ non-destructive technique also ensures that wafer contamination during production is minimal. A spectroscopic ellipsometer is developed to monitor these nanostructures during their formation in-situ and in real-time. Coupled with the development of a programmable multizone thermal processing system, we demonstrated that these nanostructures can be manipulated in real-time during processing. This is an significant improvement to current monitoring and control techniques which are typically run-to-run or wafer-to-wafer; features are measured off-line and equipment setpoints adjusted for the next batch of wafers.