Scatterometry measurement for SiGe AEI sigma-shaped gate structures of 28nm technology

Novel process control methodologies are required for SiGe gate recess structures that are used in IC manufacturing to enhance device performance. Metrology measurements of 28nm SiGe after-etch inspection U-sigma shaped and V-sigma shaped gate structures must be able to track subtle variations for several critical parameters, including SiGe-to-gate width, tip-to-gate width, sigma depth and recess depth. For production process control of these structures, a metrology tool must utilize a nondestructive measurement technique, and have high sensitivity, precision and throughput. This paper explores the capabilities of a new-generation scatterometry critical dimension (SCD) metrology tool to measure critical parameters and serve as a production process monitor for 28nm and beyond complex gate structures.