Aerial Image Sensor: In-Situ Scanner Aberration Monitor

摘要

One of the key demands for image quality testing comes from equipment engineering and process control communities. They require in-situ scanner lens quality test technique that is accurate, easy to use, and provides complete set of data quantifying the performance of the projection tools. To meet this requirement, Z37 AIS was developed. When this, in-situ technique is installed on a projection tool, it provides the following advantages: 1) the wavefront measurements can be run whenever required without any intrusion on tool setup, 2) the hardware and the software necessary to run the tests are fully integrated with the projection tool, 3) the test does not require any wafer exposure and thus the resist process does not bias or corrupt the results, 4) it involves analysis of test aerial images and thus it is directly linked to tool's imaging performance and 5) it provides complete information on the lens wavefront quality, expressed in terms of 37 Zenike polynomials. Given its characteristics, Z37 AIS methodology combines many of the key characteristics expected by the tool and process engineering communities. Z37 AIS methodology provides comprehensive test for scanner lens wavefront quality. The methodology is completely integrated with the advanced scanners. Z37 AIS technique can be used for monitoring of the tools selected for critical level imaging. Z37 AIS can also be used to fine tune the lenses specific to critical IC design requirements. Because of its capabilities combined with ease of use, Z37 AIS can become a key technique used with advanced imaging systems.