An end-point detector for planarization of semiconductor devices by chemical mechanical polishing

Abstract

A novel end-point detection technique is proposed for planarization of semiconductor wafers by chemical mechanical polishing. In this technique, a local thickness variation of polished layer is observed in-situ in detail, instead of observing a mean thickness value of the whole layer with conventional technique. The detection head owns two sensors, and mounted on a rotating platen for polishing. The first sensor is a fluid gap gage for measuring a surface position of the polished layer. The second one is an optical pick-up for measuring a bottom position of the layer. A residual thickness value of the polished layer, which is a target of this end-point detection, can be known as difference of the both values. A prototype detector was constructed. The experimental results show a 0.1μm sensitivity and a capability for manufacturing use.