Etching depth controlling method in DRAM fabricating process, involves etching two reflecting regions subsequently until etching depth of both regions are made equal

摘要

Two reflecting regions (36,37) formed on a substrate (30) is illuminated to a coherence light to generate an interference. One region is etched initially until forming a height difference between the two regions by changing the interference intensity slightly. Other region is etched until the etch depth is made same as the height difference by changing the interference intensity extremely.