Pre-Alignment Metrology Tool Corrects Within-Target Variation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing metrology systems face challenges in accurately measuring smaller targets while maintaining compatibility with larger target sizes, and they struggle with improving alignment accuracy on imperfect targets due to processing effects and sensor interactions.
Innovation Solution
A metrology system comprising a pre-alignment tool that measures targets to obtain measurement data, and a processing unit that processes this data to determine position distributions describing variation over the target, and calculates measurement corrections to account for within-target variations, thereby improving alignment sensor measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional alignment sensors are used to measure targets, then measurement process is simple, but measurement precision deteriorates due to within-target variations and processing effects
Solution Approach 1:
The pre-alignment metrology tool performs measurements and determines position distributions before the main alignment sensor operates. By预先 characterizing within-target variations and calculating measurement corrections in advance, the system compensates for processing effects and target imperfections, thereby improving alignment measurement accuracy without significantly increasing the complexity of the main alignment sensor.
2Measurement precision
If measurement corrections are calculated for each target, then alignment accuracy is improved, but processing time increases
Solution Approach 1:
The system uses the measurement data from the pre-alignment metrology tool to automatically determine position distributions and calculate measurement corrections for each target without requiring manual intervention. The processing unit autonomously performs the corrections, improving alignment accuracy while minimizing the need for additional processing time through automated workflows.
3Measurement precision
If pre-alignment metrology tool is used to measure targets, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The pre-alignment metrology tool serves as an intermediary between the target and the main alignment sensor. It performs preliminary measurements to characterize within-target variations and generates measurement corrections that are applied to the main alignment sensor's measurements. This intermediary approach improves overall measurement precision while allowing the main alignment sensor to remain relatively simple.
Data Source
AI summary
Disclosed is a metrology system comprising: a pre-alignment metrology tool operable to measure a plurality of targets on a substrate to obtain measurement data; and a processing unit. The processing unit is operable to: process said measurement data to determine for each target at least one position distribution which describes variation of said position value over at least part of said target; and determine a measurement correction from said at least one position distribution which corrects for within-target variation in each of said targets, said measurement correction for correcting measurements performed by an alignment sensor.