Laser Positioning Assembly for Abbe Error-Free Wafer Inspection
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Solution Overview
Problem
The existing wafer inspection systems suffer from Abbe error due to the large distance between the grating ruler and the wafer, leading to inaccuracies in positioning and measurement during semiconductor manufacturing processes.
Innovation Solution
A laser positioning apparatus is introduced, comprising a stage with a motion mechanism, a measurement mirror, and an orthogonality test feedback assembly, which uses laser beams to split and intersect at multiple points for precise positioning, reducing Abbe error and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a grating ruler is used for positioning the wafer on the stage, then the positioning system is simple and easy to implement, but the large distance between the grating ruler and the wafer causes Abbe error, deteriorating measurement precision
Solution Approach 1:
The patent introduces a measurement mirror as an intermediary element mounted on the wafer carrier. The laser beam reflects off this mirror to establish a measurement path that directly follows the wafer's position, eliminating the need for a separate grating ruler and removing the Abbe error source while maintaining system simplicity
Solution Approach 2:
The patent replaces the mechanical grating ruler positioning system with an optical laser measurement system. By using laser beams that reflect off a measurement mirror mounted on the carrier, the system achieves direct measurement of wafer position without mechanical intermediaries, thereby eliminating Abbe error while keeping the overall system simple
2Device complexity
If a single laser beam is used for positioning, then the system structure is simple, but it can only position one inspection point, reducing productivity
Solution Approach 1:
The patent segments a single laser beam into multiple beams using beam splitting mirrors. These multiple laser beams are directed to different inspection points on the wafer simultaneously, allowing parallel positioning and inspection of multiple points, thereby increasing productivity without significantly complicating the optical system
Solution Approach 2:
The patent creates a multi-functional laser positioning system where a single laser source serves multiple inspection points. By using beam splitting optics, one laser beam is divided into multiple beams that can position and inspect different locations on the wafer, making the system versatile and productive without requiring separate laser sources for each point
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
The laser positioning apparatus enhances the accuracy of wafer inspection by reducing Abbe error and enabling precise positioning of multiple inspection points, improving measurement and defect detection in semiconductor manufacturing.
Implementation Method 1
a measurement mirror disposed on the carrier, in which a first measurement surface of the measurement mirror intersects with the first direction, and a second measurement surface of the measurement mirror intersects with the second direction; an orthogonality test feedback assembly... the first measurement head emitting a first laser beam toward the first measurement surface in the first direction, and the second measurement head emitting a second laser beam
Implementation Method 2
an optical path assembly configured to split the second laser beam into a plurality of third laser beams emitting toward the second measurement surface in the second direction
Data Source
AI summary
The present application discloses a laser positioning apparatus and a wafer inspection system. The laser positioning apparatus comprises a stage, an orthogonality test feedback assembly, and an optical path assembly; the stage comprises a motion mechanism, a carrier, and a measurement mirror, the motion mechanism is configured to drive the carrier to move in a first direction and a second direction, the measurement mirror is disposed on the carrier, a first measurement surface of the measurement mirror intersects with the first direction, and a second measurement surface intersects with the second direction; an orthogonality test feedback assembly is provided with a first measurement head and a second measurement head, the first measurement head emitting a first laser beam toward the first measurement surface in the first direction, and the second measurement head emitting a second laser beam.