Wafer Alignment Compensation for Topography-Driven Overlay Error
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Solution Overview
Problem
The semiconductor industry faces challenges in reducing overlay errors during lithography patterning due to increased complexity and topographical variations in silicon wafers, which can distort alignment structures and lead to misalignment between successive layers, affecting device yield.
Innovation Solution
A lithographic overlay correction method that involves defining zones on the wafer and using either single-zone or multi-zone alignment compensation based on topographical variation, with multi-zone compensation using an equation to adjust alignment values across different zones, ensuring accurate wafer alignment and lithography exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If advanced lithography technologies are used to reduce geometry size, then production efficiency increases and costs decrease, but overlay errors increase and become more difficult to control
Solution Approach 1:
The wafer surface is divided into multiple zones (e.g., first zone, second zone, third zone) with different alignment compensation parameters. Each zone has its own set of alignment marks and compensation values, allowing independent optimization of alignment for different regions of the wafer, thereby reducing overall overlay errors while maintaining high productivity
Solution Approach 2:
Different alignment compensation strategies are applied to different zones based on their specific topographical characteristics. The first zone uses a first set of compensation values, the second zone uses a second set, and the third zone uses a third set, allowing each region to be optimized for its local conditions rather than applying a uniform approach across the entire wafer
2Manufacturing precision
If multi-zone alignment compensation is implemented to reduce overlay errors, then manufacturing precision improves, but device complexity increases
Solution Approach 1:
The alignment compensation process is segmented into multiple zones, each with its own alignment marks and compensation parameters. This segmentation allows the complex problem of wafer-level alignment to be broken down into manageable zone-level problems, reducing the overall system complexity while improving precision
Solution Approach 2:
The system changes alignment parameters (compensation values) based on the zone being processed. By dynamically adjusting alignment parameters according to the specific zone and its topographical characteristics, the system achieves high precision without requiring a completely complex new approach,而是 by modifying existing parameters in a controlled manner
Data Source
AI summary
A method includes receiving a wafer, measuring a surface topography of the wafer; calculating a topographical variation based on the surface topography measurement performing a single-zone alignment compensation when the topographical variation is less than a predetermined value or performing a multi-zone alignment compensation when the topographical variation is greater than the predetermined value; and performing a wafer alignment according to the single-zone alignment compensation or the multi-zone alignment compensation.