Lithography Alignment Using Split Mark Measurement for Overlay Accuracy
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Solution Overview
Problem
Current substrate processing systems face challenges in achieving high overlay accuracy in semiconductor device manufacturing due to distortion in shot area arrangements caused by processing steps like resist coating, development, etching, and CMP, making it difficult to detect a sufficient number of marks without reducing throughput.
Innovation Solution
A substrate processing system with a measurement device that measures position information of marks on a substrate and an exposure apparatus that uses this information to control the position for exposure operations, allowing for precise alignment and correction of shot area arrangements using a combination of statistical techniques and energy beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of sample shot areas is increased to improve overlay accuracy, then measurement precision is improved, but productivity deteriorates due to reduced throughput
Solution Approach 1:
The patent applies preliminary action by performing measurement operations on the first stage before the substrate is transferred to the second stage for exposure. Position information of multiple marks is measured in advance, and correction information is calculated beforehand, so that when the substrate reaches the exposure stage, the alignment is already optimized. This allows comprehensive measurement of many marks without delaying the exposure throughput.
Solution Approach 2:
The patent introduces a temporal dimension by separating measurement and exposure operations into different time stages. The measurement device operates on the first stage while the substrate is being prepared, then the substrate is transferred to the second stage for exposure. This dimensional separation allows both operations to occur without interfering with each other's timing, enabling high-precision measurement of multiple marks without reducing overall throughput.
2Manufacturing precision
If correction of nonlinear components of shot arrangement is performed to improve overlay accuracy, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent introduces an intermediary information processing layer that calculates correction information based on measured position data. Instead of directly modifying the physical alignment system, the patent uses computational algorithms to generate correction data that compensates for nonlinear distortions. This intermediary computational approach handles the complexity of nonlinear correction without requiring complex mechanical or optical adjustment mechanisms.
Solution Approach 2:
The patent replaces complex mechanical alignment adjustment systems with an information-based correction system. Instead of using additional mechanical components to physically correct nonlinear shot arrangement distortions, the patent measures the actual positions, calculates correction values, and applies these corrections through coordinate transformations during the exposure process. This substitutes mechanical complexity with computational simplicity.
Data Source
AI summary
A lithography system is provided with: a measurement device measuring position information of marks on a substrate held in a first stage; and an exposure apparatus on a second stage, the substrate for which the position information measurement for the marks has been completed, performs alignment measurement to measure position information for part of marks selected from among the marks on the substrate, and performs exposure. The measurement device measures position information of marks on the substrate to obtain higher-degree components of correction amounts of an arrangement of divided areas, and the exposure apparatus measures position information of a small number of marks on the substrate to obtain lower-degree components of the correction amounts of the arrangement of the divided areas and exposes the plurality of divided areas while controlling the position of the substrate by using the obtained lower-degree components and the higher-degree components obtained by the measurement device.