Subsurface Wafer Orientation via Laser Marking
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Solution Overview
Problem
Conventional semiconductor wafer fabrication processes involving notches lead to non-uniformities in photoresist coating, CMP film thickness, plasma density, and chemical distribution, causing contamination, equipment damage, and increased maintenance costs.
Innovation Solution
Forming a subsurface mark on the semiconductor wafer using laser irradiation to create a detectable marker for accurate orientation, avoiding the need for notches and minimizing performance degradations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a notch is formed on the wafer surface to provide orientation reference, then wafer orientation and handling are improved, but uniformity of photoresist coating and CMP film thickness deteriorates
Solution Approach 1:
The patent moves the orientation mark from the two-dimensional surface (notch on top) to the three-dimensional subsurface (mark below surface), allowing optical detection through the wafer thickness without interfering with surface processes like photoresist coating and CMP
Solution Approach 2:
The patent replaces the mechanical notch structure with an optical detection system that uses light transmission and absorption to detect subsurface marks, eliminating the need for physical surface features that interfere with manufacturing processes
2Ease of operation
If a notch is formed on the wafer surface, then wafer orientation is provided, but plasma density and chemical distribution for etching processes deteriorate
Solution Approach 1:
The orientation mark is positioned in the subsurface dimension rather than on the surface, allowing plasma processes to occur uniformly across the entire wafer surface without being disrupted by surface notches or marks
3Ease of operation
If a notch is formed on the wafer surface, then wafer orientation is provided, but wafer contamination and equipment damage increase
Solution Approach 1:
The patent extracts the orientation function from the wafer surface and places it in the subsurface, removing the source of contamination (surface notch) while preserving the orientation capability through optical detection of subsurface marks
Solution Approach 2:
The patent creates an optical copy or representation of the orientation mark in the subsurface that can be detected through light transmission, replacing the physical surface notch with a detectable subsurface feature that does not cause contamination
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
Improves yield by maintaining uniformity across the wafer surface, reducing contamination, equipment damage, and maintenance requirements, while providing a reliable orientation reference.
Implementation Method 1
a sensor configured to detect the subsurface mark based on light transmission
Implementation Method 2
the subsurface mark alters light transmission
Data Source
AI summary
A system for orienting a semiconductor wafer. The system includes a wafer retaining device configured to retain a semiconductor wafer, a light source configured to emit light toward an edge exclusion area of the wafer, and a lens configured to direct and focus light emitted from the light source at a subsurface first part of a first portion of the wafer to alter a crystalline structure of the subsurface first part and form a subsurface mark that is detectable using light of a predetermined wavelength, a predetermined transmittance through the wafer, and at a predetermined reflectance angle relative to an axis of rotation of the wafer and based on the predetermined wavelength.