Photomask Pattern Optimization for Resist Shape Accuracy
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Solution Overview
Problem
Current photomask manufacturing methods fail to accurately form three-dimensional resist patterns due to exposure condition fluctuations and development characteristics of the resist, leading to shape errors and edge placement issues.
Innovation Solution
A method that sets exposure conditions based on resist thickness data and development characteristics, calculates a cost function for edge placement errors, and adjusts the photomask pattern to minimize errors between predicted and target shapes, using a simulation apparatus to optimize the pattern for accurate resist formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photomask manufacturing methods are used, then the manufacturing process is simple, but shape errors and edge placement errors occur due to exposure condition fluctuations and resist development characteristics
Solution Approach 1:
The patent applies preliminary action by performing simulation calculations before actual photomask manufacturing to predict resist shape formation. The method calculates cost functions related to edge placement errors and adjusts the photomask pattern in advance based on simulated exposure and development processes, thereby preventing shape errors before they occur in production.
Solution Approach 2:
The patent implements feedback by using simulation results to iteratively adjust the photomask pattern. The cost function calculation provides feedback on the predicted resist shape accuracy, and the pattern is modified based on this feedback to minimize edge placement errors, creating a closed-loop optimization process.
2Reliability
If exposure conditions are standardized, then the manufacturing process is stable, but shape errors occur due to inevitable exposure condition fluctuations
Solution Approach 1:
The patent applies preliminary anti-action by pre-compensating for exposure condition fluctuations through simulation. The method predicts how variations in exposure conditions will affect resist shape formation and adjusts the photomask pattern in advance to counteract these expected deviations, thereby maintaining accuracy despite process variations.
Solution Approach 2:
The patent uses parameter changes by modifying the photomask pattern parameters based on simulation results. The cost function optimization adjusts critical dimensions and pattern geometry to compensate for exposure condition variations, transforming the pattern parameters to achieve desired resist shape accuracy under fluctuating conditions.
3Productivity
If the photomask pattern is designed without simulation, then the design process is fast, but edge placement errors occur due to resist development characteristics
Solution Approach 1:
The patent replaces manual trial-and-error pattern design with automated simulation-based optimization. Computer algorithms calculate cost functions and adjust patterns based on simulated exposure and development processes, substituting computational automation for conventional manual design methods and achieving both speed and accuracy.
Solution Approach 2:
The patent uses virtual copying by creating a digital simulation model of the resist formation process. The simulation replicates the physical exposure and development processes, allowing pattern optimization to be performed in the virtual domain before manufacturing, thereby eliminating the need for repeated physical prototypes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method significantly reduces shape errors and edge placement errors, ensuring precise resist pattern formation even under varying exposure conditions, thereby improving the accuracy of semiconductor element patterning.
Implementation Method 1
a resist is formed into a three-dimensional shape by using a photomask
Data Source
AI summary
A manufacturing method of a photomask according to the embodiment sets an exposure condition applied when a resist is formed into a three-dimensional target shape by using a photomask including a plurality of light-shielding areas. Subsequently, the method sets a hypothetical target shape obtained by correcting a target shape based on a development characteristic of the resist for the exposure condition. Subsequently, the method creates a pattern of the photomask corresponding to the hypothetical target shape. Subsequently, the method simulates a prediction shape of the resist when the pattern is used. Subsequently, the method calculates a cost function related to an error between the prediction shape and the hypothetical target shape. Subsequently, the method adjusts the pattern based on a result of the calculation of the cost function.