Wafer Edge Measurement Using Diffuse Reflection Triangulation
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Solution Overview
Problem
Existing methods for measuring the shape of semiconductor wafer edges are limited by the need for polished or etched surfaces to reflect specular light, cannot capture fine adherence and chips, require complex optical systems, and take too long to measure the entire circumference.
Innovation Solution
An edge portion measuring apparatus that uses diffuse reflected light from a laser projected onto the wafer edge, rotating the wafer to measure the entire edge using a triangulation method, allowing for simple optical systems and quick measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If specular reflection measurement method is used, then measurement precision can be improved, but the surface must be polished or etched to reflect specular light, which increases process complexity and limits measurement to specific stages
Solution Approach 1:
The patent changes the measurement parameter from specular reflection to diffuse reflection. By using diffuse reflected light from a laser projected onto the wafer edge, the measurement can be performed on surfaces without polishing or etching, thus eliminating the need for complex surface preparation processes while maintaining measurement capability across all manufacturing stages
Solution Approach 2:
The patent replaces the complex optical system requiring precise alignment for specular reflection with a simpler diffuse reflection measurement system. The laser projects light onto the edge and the diffuse reflected light is detected, eliminating the need for complex optical paths and precise mechanical alignment
2Device complexity
If projected image method is used, then measurement setup can be simplified, but fine adherence, chips, and streaks cannot be captured
Solution Approach 1:
The patent applies local quality by using a laser to project light specifically onto the edge portion of the wafer rather than illuminating the entire wafer surface. This concentrated light projection on the local edge region enables detection of fine defects such as adherence, chips, and streaks that would be missed in general projected image methods
3Measurement precision
If confocal optical system with light condensation is used, then measurement precision can be improved, but the system becomes large-scale and complicated, and measurement time increases
Solution Approach 1:
The patent replaces the complex confocal optical system with a simpler diffuse reflection measurement system. Instead of using light condensation and confocal detection mechanisms, the system projects laser light and detects diffuse reflected light directly, eliminating the need for complex optical components and reducing measurement time
Solution Approach 2:
The patent extracts only the essential measurement function from the complex confocal system. By using diffuse reflection measurement, it takes out the core capability of edge detection while removing the unnecessary complex optical mechanisms, achieving both simplicity and speed
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
Enables precise and rapid measurement of the entire wafer edge, detecting defects and tool/chemical life, independent of surface condition, with a simple setup.
Implementation Method 1
a light receiving detection unit that receives diffuse reflected light that the laser light projected from the light projecting portion is reflected at the edge portion of the wafer
Data Source
AI summary
An edge portion measuring apparatus for measuring shape of an edge portion of a wafer, including, a holding portion that holds the wafer, a rotating means for rotating the wafer, a sensor including a light projecting portion for projecting a laser light from a light source onto the edge portion of the wafer held by the holding portion, and a light receiving detection unit receiving diffuse reflected light that the laser light projected is reflected at the edge portion of the wafer, wherein, rotating the wafer while holding the wafer, at least in a range from normal direction of a held surface of the wafer to normal direction of a surface opposite to the held surface, projecting the laser light and detecting the diffuse reflected light by the sensor, being able to measure the shape of an entire area of the edge portion of the wafer by a triangulation method.