METHOD FOR MEASURING OVERLAY ACCURACY OF SEMICONDUCTOR DEVICE

摘要

PURPOSE: A method for measuring an overlay accuracy of a semiconductor device is provided to measure an overlay accuracy between layers after exposing a wafer and performing a thermal process for the exposed wafer. CONSTITUTION: A method for measuring an overlay accuracy of a semiconductor device comprises the following steps. A first aligned mark arranged with various bars is arranged at an edge portion of an exposure field of a first layer. A second aligned mark of the same shape as the first aligned mark is formed beside the first aligned mark formed on the first layer when exposing a second layer. A thermal process is performed after exposing the second layer. The aligned mark is measured by using a difference of reflexibility between an exposing area(1) and non-exposing area. A thermal processed wafer is loaded on a wafer stage. And an overlay accuracy between two layers is measured.