EL-3 application to 0.5 μm semiconductor lithography

Abstract

The application of IBM’s 3rd generation direct write electron beam lithography tool EL-3 has been extended into the submicron region. This was accomplished with tool modifications in conjunction with suitable process adjustments. EL-3 is presently being used in both development and manufacturing for the exposure of wafers and masks. It was designed as a high current, high throughput tool to cover lithography requirements down to 1 μm minimum dimensions. To move into the 0.5 μm realm, no basic architecture changes were made, but the beam current, deflection speeds, and maximum spot and field sizes were reduced to make the trade-offs against throughput that were necessary and acceptable for the system’s application to technology development. A single layer resist process was devised to demonstrate fully the performance capability of the tool. The process uses top surface imaging which allows one to analyze tool performance without excessive distortions. Spot-to-spot butting and illumination consistency were monitored using this process. Linewidth tolerance and overlay results obtained with the new tool/process configuration will be reported. Top surface imaging, whether in a single or multilayer resist process, represents the most viable approach for submicron electron-beam lithography.