Dynamic Correction Function Selection for Semiconductor Overlay Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current exposure apparatuses face challenges in accurately correcting non-linear components of the two-dimensional grid for overlay exposure in microdevice manufacturing, particularly in semiconductor production, due to variations in overlay error between lots and the complexity of non-linear grid components, which affects the overlay accuracy and throughput.
Innovation Solution
The exposure apparatus is equipped with multiple correction functions that can select an optimum correction function based on predetermined information associated with the exposure apparatus and photosensitive objects, considering the non-linear components of the two-dimensional grid, allowing for effective correction of non-linear components in a short time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple correction functions with different degrees of non-linear components are provided, then overlay accuracy is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic selection of correction functions based on the actual measurement results of shot area positions. The system automatically determines which correction function (first through fourth types with different non-linear component degrees) to apply by evaluating the measured overlay errors, making the correction approach adaptive rather than static. This allows the system to use simple correction when needed and complex correction when necessary, resolving the contradiction between accuracy and complexity.
Solution Approach 2:
The patent changes the parameter of correction function selection based on measurement results. By evaluating the degree of non-linearity in the measured shot area positions, the system dynamically adjusts the correction function type (from simple linear correction to complex high-order non-linear correction). This parameter-based adaptation enables the system to achieve high overlay accuracy only when non-linear components are present, while using simpler correction methods when linear approximation suffices, thus managing device complexity effectively.
2Manufacturing precision
If non-linear components of the grid are corrected using measurement of multiple shot areas, then overlay accuracy is improved, but measurement time increases
Solution Approach 1:
The system dynamically adjusts the number and distribution of shot areas to be measured based on the detected overlay error characteristics. When non-linear components are detected, the system increases the number of measured shot areas and adjusts their distribution to better capture the non-linearity. This dynamic measurement adjustment ensures accurate correction while minimizing unnecessary measurements, thereby reducing overall correction time while maintaining high overlay accuracy when needed.
Solution Approach 2:
The patent applies partial measurement action by selecting an optimal number of shot areas for measurement based on the actual correction needs. Rather than always measuring all possible shot areas, the system determines the minimum sufficient number of measurements required to accurately capture the non-linear components present in the specific lot. This partial action approach reduces measurement time while maintaining adequate correction accuracy, avoiding excessive measurement when the correction function can be determined with fewer data points.
Data Source
AI summary
At Step 602, the grid of a wafer loaded into an exposure apparatus is approximated by a mathematical function fitting up to, for example, a cubic function, and at Step 612, the magnitude of a residual error between the position of a sample shot area obtained by the function and an actually measured position is compared with a predetermined threshold value. GCM measurement is performed in a mathematical function mode in a subroutine 616, or it is performed in a map mode in a subroutine 616, on the basis of the result of the comparison. In addition, it is determined whether to extract non-linear components from the wafer in each lot on the basis of a variation in the temperature of the wafer (Step 622) and a variation in random error between the wafers (Step 624).