Exposure Apparatus Alignment Correction for Wafer Warping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor device manufacturing, the overlay accuracy between lower-layer-side and upper-layer-side patterns is compromised due to wafer warping caused by film stress differences, leading to reduced performance of the semiconductor device.
Innovation Solution
An exposure apparatus with an alignment correction value calculating unit that uses measured alignment data, focus maps, and historical positional deviation corrections to accurately position the upper-layer-side pattern relative to the lower-layer-side pattern, accounting for wafer distortion and stress differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional exposure methods are used on warped wafers, then the manufacturing process can proceed, but the overlay accuracy between layers deteriorates
Solution Approach 1:
The system performs preliminary measurement of the wafer surface shape using a focus map measuring unit before exposure, and pre-calculates alignment correction values based on these measurements. This allows the exposure apparatus to compensate for wafer warping in advance, ensuring accurate overlay between layers despite the warped wafer morphology.
Solution Approach 2:
The system uses alignment data measuring units to detect actual pattern positions on the wafer, compares these with target positions, and feeds back correction information to adjust subsequent exposure operations. This closed-loop feedback mechanism continuously optimizes alignment accuracy despite wafer warping.
2Productivity
If film stress differences are present between front and rear surfaces, then the semiconductor manufacturing process can continue, but wafer warping occurs which reduces overlay accuracy
Solution Approach 1:
The system changes the parameter space by measuring not only lateral position but also focal depth variations across the wafer surface. By incorporating focus map data that reflects the three-dimensional wafer morphology caused by film stress, the system calculates comprehensive alignment correction values that account for both lateral and vertical deviations, thereby maintaining precision despite warping.
3Device complexity
If alignment correction is performed without focus map measurement, then the process is simpler, but the correction accuracy for warped wafers is insufficient
Solution Approach 1:
The exposure apparatus integrates multiple functions into unified measurement units that can perform both focus map measurement and alignment data measurement. This multi-functionality allows the system to gather comprehensive wafer surface information without adding separate complex measurement systems, achieving high measurement precision while controlling device complexity.
Data Source
AI summary
An exposure apparatus according to an embodiment controls the positioning between layers using an alignment correction value calculated on the basis of lower layer position information of a lower-layer-side pattern and upper layer position information of an upper-layer-side pattern. The lower layer position information includes alignment data, a focus map, and a correction value which is set on the basis of the previous substrate. The upper layer position information includes alignment data, a focus map, and a correction value which is a correction value for the positioning and is used when the upper-layer-side pattern is transferred.