Wafer Laser Separation With Backside Liquid Debris Removal
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Solution Overview
Problem
Existing laser processing apparatuses fail to effectively reduce debris adherence to the second surface of semiconductor wafers during the separation of the outer circumferential portion, hindering subsequent processing steps.
Innovation Solution
A laser processing apparatus is designed with a stage that holds the semiconductor wafer such that the second surface faces the wafer holding surface, and a nozzle supplies a liquid from the second surface side to the area irradiated with the laser beam, reducing debris adherence by washing it away.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a laser beam is applied from the first surface side to separate the outer circumferential portion, then the separation process is effective, but debris adheres to the second surface
Solution Approach 1:
The patent applies liquid from the second surface side (opposite side) rather than from the first surface side where the laser beam is applied. This inverted approach allows the liquid to effectively remove debris from the second surface without interfering with the laser processing on the first surface, thereby resolving the contradiction between effective separation and debris adherence reduction.
Solution Approach 2:
The liquid acts as an intermediary substance that mediates between the laser processing operation and the second surface. By introducing this intermediary from the opposite side, the system can simultaneously maintain effective laser separation while preventing debris adherence through the liquid's cleaning action on the second surface.
2Ease of manufacture
If the wafer is held with the first surface facing the holder, then the laser processing is straightforward, but debris management on the second surface becomes difficult
Solution Approach 1:
The liquid supplied from the second surface side serves as an intermediary that enables effective debris management without complicating the wafer holding configuration. This intermediary approach allows the system to maintain the simple first-surface-facing holder arrangement while effectively managing debris on the second surface through the liquid's cleaning action.
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 apparatus significantly reduces debris height on the second surface to less than 10 μm, preventing hindrance to subsequent tape application and ensuring smooth processing.
Implementation Method 1
A laser beam generated in the laser source is applied to the semiconductor wafer through the liquid column. Thus, the outer circumferential portion is separated from the semiconductor wafer.
Implementation Method 2
The nozzle supplies a liquid from a second surface side. The liquid that has reached the first surface forms a liquid layer on the first surface... the liquid layer reduces adhering of the debris to the first surface.
Data Source
AI summary
A laser processing apparatus includes a stage having a wafer holding surface, a laser irradiation mechanism, and a nozzle. On the wafer holding surface, a semiconductor wafer having a first surface and a second surface opposite to the first surface is disposed such that the wafer holding surface faces the second surface. The laser irradiation mechanism applies a laser beam from a first surface side. The nozzle supplies a liquid from a second surface side.