Wafer Alignment Compensation for Photolithography Warpage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing photolithography alignment methods suffer from significant alignment errors due to wafer warpage, leading to reduced overlay accuracy and increased production inefficiency, as current compensation methods are inadequate in accounting for the deformation of the exposed surface.
Innovation Solution
An alignment method and system that utilize an alignment mark and reference point on the wafer surface, with levelling measurements to obtain an expansion reference value, which is then used to calculate an expansion compensation value to adjust photolithography parameters, effectively addressing the warpage-induced alignment errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional photolithography alignment methods are used, then the alignment process is simple and fast, but the alignment error is large due to wafer warpage
Solution Approach 1:
The patent performs levelling measurements and calculates expansion compensation values before the actual photolithography exposure process. By pre-measuring the wafer surface topography and pre-calculating compensation values, the system prepares correction data in advance, allowing the subsequent exposure to proceed with improved accuracy without adding complexity to the main production flow
Solution Approach 2:
The patent introduces an intermediary calculation module that computes expansion compensation values based on levelling measurement data. This intermediary layer translates raw surface topography measurements into actionable compensation parameters that can be applied during photolithography, bridging the gap between measurement and exposure processes
2Manufacturing precision
If wafer warpage is not compensated, then the process is efficient and fast, but overlay accuracy deteriorates significantly
Solution Approach 1:
The patent replaces physical mechanical alignment adjustments with computational compensation methods. Instead of mechanically adjusting the wafer or lithography system to account for warpage, the system uses optical levelling measurements combined with mathematical expansion compensation calculations to achieve alignment, reducing the need for time-consuming mechanical iterations
Solution Approach 2:
The patent changes the approach from direct physical alignment to parameter-based compensation. By measuring surface topography parameters and calculating expansion compensation values, the system transforms the alignment problem into a parameter correction task, where computational parameters are adjusted to compensate for physical warpage effects
Data Source
AI summary
An alignment method and an alignment system are provided. The alignment method includes: providing a wafer including an exposed surface, wherein an alignment mark and a reference point with a reference distance are provided on the exposed surface; placing the wafer on a reference plane; performing an alignment measurement on the exposed surface to obtain a projection distance, configured as a measurement distance, between the alignment mark and the reference point on the reference plane; performing a levelling measurement between the exposed surface and the reference plane to obtain levelling data of the exposed surface; obtaining a distance, configured as an expansion reference value, between the alignment mark and the reference point in the exposed surface; obtaining an expansion compensation value based on a difference between the expansion reference value and the reference distance; and adjusting parameters of a photolithography process based on the expansion compensation value for an alignment.