Alternating Phase Shift Mask Inspection Through the Use of Phase Contrast Enhancement Techniques

摘要

Alternating Phase Shift Masks (altPSM's) are an option for the production of critical layers at the 100 nm technology node and below produced at ArF lithographic wavelength. Successful implementation of altPSM's depends upon the ability to successfully inspect, disposition and repair defects that occur during the manufacturing process. One technique previously described to improve phase defect contrast was the use of simultaneous transmitted and reflected light. The previously described technique provided for improved phase defect detection in altPSM's produced for the 130 nm node at a 248 nm lithographic wavelength. This work describes the results from a die-to-die inspection method that improves phase defect contrast in transmitted light for altPSM's produced for the 100 nm node at a 193 nm wavelength. The improved phase defect detection technique addresses the challenges of decreasing linewidth/pitch and reduced defect phase resulting from the decrease in lithographic wavelength relative to the inspection wavelength of light. The improved phase defect detection method also provides a method to determine whether a defect is a binary, phase bump or phase divot type of defect. Results are compared against the previous inspection methods. A test vehicle for gathering sensitivity performance data is described along with the results obtained from the inspection system.