Exposure Mask Data Correction via Dispersion-Aware Metrology
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Solution Overview
Problem
Existing methods for obtaining exposure data for manufacturing exposure masks in photolithography processes face challenges in accurately measuring critical dimensions, particularly in consideration of dispersion, which affects the precision of the exposure mask.
Innovation Solution
A method involving the receipt of MTO design data, performing a mask data preparation operation, extracting two-dimensional contours of test patterns through simulation using a mask process model, measuring critical dimensions at specific points, and calculating average critical dimensions with and without dispersion consideration to determine if exposure data needs correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If critical dimensions are measured without considering dispersion, then measurement process is simple, but measurement precision is insufficient
Solution Approach 1:
The patent applies preliminary action by performing simulation to extract two-dimensional contours of test patterns before actual measurement. This allows the establishment of a mask process model that accounts for dispersion effects in advance, enabling more precise critical dimension measurements while systematically managing the complexity through pre-computed reference data
Solution Approach 2:
The patent introduces an intermediary metrology algorithm that acts as a mediator between raw measurement data and critical dimension values. This algorithm considers dispersion effects and measurement uncertainties, transforming simple measurements into precise critical dimension data while accounting for various sources of variation without requiring direct complex measurement procedures
2Manufacturing precision
If exposure data is not corrected, then manufacturing process is fast, but manufacturing precision is poor
Solution Approach 1:
The patent implements feedback by calculating MTT (mean to target) values comparing simulated critical dimensions against target values, then using this feedback to determine whether exposure data correction is necessary. This closed-loop approach ensures manufacturing precision by only correcting data when needed, maintaining productivity by avoiding unnecessary correction steps
Solution Approach 2:
The patent applies parameter changes by adjusting exposure data parameters (such as dose or focus parameters) based on the calculated MTT values and tolerance thresholds. When the difference between MTT values exceeds the threshold, the exposure data parameters are modified to achieve the desired critical dimension precision, balancing correction needs with process efficiency
Data Source
AI summary
A method for obtaining exposure data may be provided. MTO (Mask Tape Out) design data for a mask pattern may be received. A mask data preparation operation with respect to the MTO design data may be performed to obtain exposure data. Two-dimensional contours of a plurality of types of test patterns in an exposure mask may be extracted through simulation using a mask process model. First critical dimensions may be measured at measurement points of the contour of each of the plurality of types of test patterns by using a metrology algorithm. The first critical dimensions may be averaged to obtain a first average critical dimension for each of the plurality of types of test patterns. Second critical dimensions in consideration of dispersion in each of the plurality of types of test patterns may be measured using an inverse function of a standard normal distribution, and the second critical dimensions may be averaged to obtain a second average critical dimension for each of the plurality of types of test patterns. A mean to target (MTT) value may be calculated as a difference between the second average critical dimension and a target critical dimension for each of the plurality of types of test patterns. Differences between ones of the MTT values may be calculated. When one or more of the differences between the ones of the MTT values may is outside of a tolerance threshold, the exposure data may be corrected.