Trench depth measurement method for wafer patterning

Abstract Various types of three-dimensional vertical capacitor cells have been proposed for realizing very-large-scale integration direct random access memories (VLSI DRAMs). With vertical processing of the VLSI DRAMs, the need for a noncontacting method of measuring trench depth has greatly increased. This paper describes trench depth measurement systems with an optical interference technique. Experimental results are described in addition to the measurement principle and configurations of the system. With these systems, the trench depth can be quickly and precisely measured without cleaving the wafers. Therefore, they are applicable to in-fine monitoring systems in the VLSI DRAMs fabrication process.