Wafer Alignment Using Notch-Based Geometric Reference Lines
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Solution Overview
Problem
Conventional wafer alignment methods are prone to recognition errors due to deformation of features on the wafer surface, especially when a resin layer is applied, leading to potential defects during processing.
Innovation Solution
A method and apparatus that utilize three points (center point, first imaginary point, and second imaginary point) to improve recognition accuracy by producing reference lines and imaginary lines with specific angles, allowing for precise alignment of the wafer center line with the work table alignment line, even when traditional features are obscured.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a resin layer is coated on the wafer surface to protect it, then the wafer surface is protected, but the camera cannot recognize the align key or pattern on the surface
Solution Approach 1:
The patent introduces an intermediary reference structure (the regular triangle formed by three notches) that mediates between the protected wafer surface and the camera recognition system. The notches are designed to be visible through the resin layer, serving as an intermediary reference that allows alignment without requiring direct recognition of obscured surface features.
Solution Approach 2:
The patent creates a simplified copy or representation of the alignment reference system. Instead of relying on complex surface patterns that are obscured by resin, the system uses a simplified geometric construction (regular triangle from three notches) that can be reliably recognized through the resin layer, effectively copying the essential alignment function in a form that penetrates the resin barrier.
2Ease of operation
If conventional alignment methods use balls or lines on the wafer surface, then alignment can be achieved, but recognition errors occur when these features are deformed
Solution Approach 1:
The patent changes the geometric parameters of the alignment reference system. Instead of using simple balls or lines that can be deformed, it uses three notches arranged to form a regular triangle, which provides redundant geometric constraints. This parameter change makes the alignment system more robust against deformation, as the regular triangle geometry can still be recognized even if individual notches are slightly distorted.
Solution Approach 2:
The patent performs preliminary geometric construction to establish the center line before actual alignment occurs. By pre-defining the regular triangle from three notches and calculating its center line in advance, the system prepares a robust reference that is less sensitive to deformation, enabling reliable alignment even when surface features are compromised.
Data Source
AI summary
A method of aligning a wafer includes recognizing images of the wafer accommodated on a work table and a notch of the wafer using a camera, designating at least one notch point of the notch in a recognized image, producing at least one reference line using the designated notch point in the recognized image, designating a center point of the reference line in the recognized image, producing an imaginary line having an angle with respect to the reference line from the center point of the reference line in the recognized image, producing a center line of the wafer using the imaginary line in the recognized image, and aligning the wafer using an alignment apparatus to allow the center line of the wafer and an alignment line of the work table to be matched.