Method and apparatus for fabricating wafer by calculating process correction parameters
AssigneeQoniac GmbH
InventorBoris Habets
Life of this patent
Estimating the term…
Abstract
A method of calculating an overlay correction model in a unit for the fabrication of a wafer is disclosed. The method comprises measuring overlay deviations of a subset of first overlay marks and second overlay marks by determining the differences between the subset of first overlay marks generated in the first layer and corresponding ones of the subset of second overlay marks generated in the second layer.
Claims7
An apparatus for fabrication of a wafer with a structural pattern comprising:
- an exposure tool for exposure of the wafer;
- an overlay measurement tool for measuring a subset of overlay deviations between lower first overlay marks and second overlay marks in a photoresist layer on the wafer;
- and
- a process correction unit connected to the overlay measurement tool and accepting the measured subset of overlay deviations, calculating from the overlay deviations wafer fine model corrections parameters, for a plurality of overlay positions estimating overlay residuals from the wafer fine model correction parameters, and calculating a set of process correction parameters for the exposure tool from the overlay residuals and providing the set of process correction parameters to the exposure tool.
A method for aligning and exposing a wafer with a structural pattern having overlay marks, comprising lower first overlay marks and second overlay marks, in an exposure tool, the method comprising:
- feeding from an exposure controller the exposure tool with an initial overlay model;
- coating the wafer having lower first overlay marks with a photoresist layer;
- producing with the exposure tool a structure in a plurality of exposure fields incorporating second overlay marks on the photoresist layer;
- measuring with an overlay measurement tool overlay deviations by comparing a subset of the first overlay marks with corresponding ones of the second overlay marks and calculating from the overlay deviations wafer fine model correction parameters;
- passing the measured overlay deviations to a process correction unit;
- estimating with the process correction unit overlay residuals for a plurality of overlay positions from the wafer fine model correction parameters, thereby generating a set of process correction parameters;
- passing the set of process correction parameters to the exposure controller;
- and
- feeding from the exposure controller the set of process correction parameters to the exposure tool.
Dependencies are inferred from the claim text.