Tool Induced Shift Reduction for Overlay Metrology
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Solution Overview
Problem
Current optical overlay metrology techniques face limitations in accurately measuring tool-induced shift (TIS) due to measurement uncertainties, which can lead to reduced wafer throughput and potential yield issues in semiconductor manufacturing, as they require extensive measurements on every workpiece.
Innovation Solution
A method that determines a baseline TIS level on an initial workpiece with comprehensive measurements and subsequently performs reduced TIS measurements on subsequent workpieces, using a threshold comparison to decide on the need for full measurements, thereby maintaining high throughput while ensuring accurate TIS assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If comprehensive TIS measurements are performed on every workpiece, then measurement precision is improved, but productivity deteriorates
Solution Approach 1:
The patent applies partial action by performing comprehensive TIS measurements only on a subset of workpieces (e.g., every nth workpiece or based on specific criteria) rather than every workpiece. This reduces the overall measurement burden while still maintaining adequate TIS monitoring and correction capabilities for the manufacturing process.
2Productivity
If TIS measurements are reduced for subsequent workpieces, then productivity is improved, but measurement precision deteriorates
Solution Approach 1:
The patent applies preliminary action by establishing baseline TIS measurements and correction factors from initial comprehensive measurements on reference workpieces. These pre-established correction factors are then applied to subsequent workpieces, eliminating the need for repeated comprehensive measurements while maintaining measurement accuracy through the use of the predetermined correction data.
3Reliability
If baseline TIS is determined with comprehensive measurements, then reliability is improved, but loss of time occurs
Solution Approach 1:
The patent performs comprehensive baseline TIS measurements during initial setup or calibration phases before production begins. This preliminary action establishes reliable correction factors that can be stored and reused for subsequent workpieces, ensuring measurement reliability without repeating the time-consuming comprehensive measurements during actual production runs.
Data Source
AI summary
One embodiment relates to a method for semiconductor workpiece processing. In this method, a baseline tool induced shift (TIS) is measured by performing a baseline number of TIS measurements on a first semiconductor workpiece. After the baseline TIS has been determined, the method determines a subsequent TIS based on a subsequent number of TIS measurements taken on a first subsequent semiconductor workpiece. The subsequent number of TIS measurements is less than the baseline number of TIS measurements.