Patent ID: 9679822
Date: 2017-06-13
CPC Classifications: H01L

Claim:
1. A method for monitoring a geometry shift of an epitaxial growth, the method comprising the steps of: forming a plurality of first trenches, a plurality of second trenches and a plurality of third trenches on a top surface of a substrate of a semiconductor wafer; growing an epitaxial layer on the substrate; the epitaxial layer covering the plurality of first trenches and the plurality of second trenches; the epitaxial layer not covering the plurality of third trenches; a plurality of first recesses and a plurality of second recesses being formed on a top surface of the epitaxial layer; each first recess being above a respective first trench; and each second recess being above a respective second trench; depositing a photoresist layer covering the epitaxial layer, the plurality of first recesses, the plurality of second recesses and the plurality of third trenches; performing a lithography process on the photoresist layer so as to form a plurality of first openings, a plurality of second openings, and a plurality of third openings; a respective first opening being aligned with said each first recess; a respective second opening being aligned with said each second recess; and a respective third opening being aligned with each third trench; measuring a respective first offset between a top center and a bottom center of said each first recess; and determining a respective offset value of the top center from the bottom center of said each first recess; and measuring a respective second offset between a top center or a bottom center of said each second recess and a center of the respective second opening; measuring a respective third offset between a center of said each third trench and a center of the respective third opening; and measuring a respective offset value of said each second recess from a difference between the respective second offset and the respective third offset.