Impact of scanner tilt and defocus on CD uniformity across field

Abstract

Gate critical dimension (CD) uniformity across field is a key parameter in total gate CD control; it is especially important for highly integrated microprocessor chip with large die size and high speed. Intensive study has been conducted to reveal the impact of scanner leveling tilt, defocus and illumination distribution on CD uniformity across field. Correspondingly CD in die range, vertical-horizontal CD bias, resist side wall angle and profile have all been characterized and monitored for each individual scanner. The monitoring methodology we have established enables us to maintain these CD parameters within fairly tight control range, and also provided efficient and accurate data on tool capability and marginality for running production.

Design of an integrated aerial image sensor

“…Despite the poor control conditions of this bench top experiment, most of these errors can be avoided in the actual sensor operation within a state of the art stepper/scanner system. For example, typical illumination uniformities have a range of about 1.5% [13], but they can be further reduced with the help of illumination filters to values better than 0.5%, which has no significant effect on the printed linewidth variation. For the actual sensor design, the position of the shifted aperture groups is fixed on the sensor mask, so many of the placement problems inherent in the bench top experiment will not be present in the actual integrated sensor.…”