Laser Wafer Separation for Chamfered Edge Stability
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Solution Overview
Problem
The challenge of stably separating wafers with chamfered outer circumferential parts using laser beams is hindered by diffuse reflection and focal point deviation, leading to inconsistent separation and potential breakage or uneven thickness in separated wafers.
Innovation Solution
A method involving processing the wafer to remove parts along the curved chamfered edge, forming a separation origin inside the wafer by positioning a laser beam's focal point within the wafer and moving it relative to the wafer to prevent diffuse reflection, and then separating the wafer using an external force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the outer circumferential part of the wafer is chamfered to prevent breakage and chipping, then the reliability of wafer handling is improved, but the laser beam processing becomes unstable due to diffuse reflection and focal point deviation
Solution Approach 1:
The patent applies preliminary action by performing the chamfering process before laser beam separation. The outer circumferential surface is pre-chamfered to prevent breakage and chipping during handling, and then the laser beam separation is performed with adjusted parameters (wavelength selection, focal point positioning) to account for the chamfered surface characteristics, ensuring both handling reliability and separation precision are achieved
2Productivity
If a laser beam is used to separate the wafer, then the manufacturing efficiency is improved, but the separation becomes unstable when the outer circumferential part is chamfered due to diffuse reflection
Solution Approach 1:
The patent applies parameter changes by selecting a specific laser beam wavelength that has appropriate transmissibility characteristics for the wafer material. This wavelength selection, combined with adjusted focal point positioning, allows the laser beam to effectively separate the wafer even when the outer circumferential surface is chamfered, maintaining both high manufacturing efficiency and reliable separation stability
3Manufacturing precision
If the focal point of the laser beam is positioned inside the chamfered outer circumferential part, then the separation origin can be formed, but the focal point position deviates from the envisaged position due to the curved surface
Solution Approach 1:
The patent applies feedback by implementing a control mechanism that monitors and adjusts the focal point position of the laser beam. The focal point position information is fed back to the control system, which then adjusts the laser beam parameters to ensure the separation origin is formed at the correct position, compensating for deviations caused by the chamfered outer circumferential surface
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
This approach allows for stable separation of wafers without diffuse reflection or focal point deviation, ensuring consistent thickness and reducing the risk of breakage or uneven separation.
Implementation Method 1
a separation origin forming step of, after the processing step, forming a separation origin inside the wafer by positioning a focal point of a laser beam with a wavelength having transmissibility with respect to the wafer inside the wafer and executing irradiation with the laser beam
Implementation Method 2
positioning a focal point of a laser beam with a wavelength having transmissibility with respect to the wafer inside the wafer
Implementation Method 3
a separation step of separating the wafer into a wafer having the first surface and a wafer having the second surface from the separation origin by giving an external force after the separation origin forming step
Data Source
AI summary
A wafer having a first surface, an opposite second surface, and an outer circumferential surface that includes a curved part curved outward in a protruding manner is separated into two wafers. Part of the wafer is removed along the curved part, and a separation origin is formed inside the wafer by positioning the focal point of a laser beam with a wavelength having transmissibility with respect to the wafer inside the wafer and executing irradiation with the laser beam while the focal point and the wafer are relatively moved in such a manner that the focal point is kept inside the wafer. The wafer is separated into two wafers by an external force.