Optical Device Wafer Transfer via Laser Buffer Decomposition
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Solution Overview
Problem
The existing optical device wafer processing method faces challenges in accurately transferring the optical device layer from an epitaxy substrate to a transfer substrate due to warpage caused by differences in linear expansion coefficients, leading to potential damage to the optical device layer and incomplete peeling of the epitaxy substrate.
Innovation Solution
The method involves bonding a transfer substrate to the optical device layer, cutting it along predefined streets to relieve warpage, attaching it to a supporting member, applying a laser beam with a focused point in the buffer layer to decompose it, and peeling off the epitaxy substrate, with the cutting process using either a cutting blade or laser to create division grooves that alleviate adverse effects from N2 gas production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the transfer substrate is bonded to the optical device layer by heating to 220-300°C, then the bonding strength is improved, but warpage occurs due to difference in coefficient of linear expansion between the epitaxy substrate and transfer substrate
Solution Approach 1:
The patent divides the epitaxy substrate into multiple independent units by cutting along the streets that separate different optical device regions. This segmentation allows each unit to independently manage thermal expansion stresses, preventing overall warpage of the bonded structure while maintaining strong bonding between the transfer substrate and optical device layer.
2Manufacturing precision
If the focal point of the laser beam is set in the buffer layer for peeling, then the decomposition of the buffer layer is improved, but accurate positioning becomes difficult due to warpage
Solution Approach 1:
By segmenting the substrate into smaller units through cutting along streets, the patent reduces the overall warpage of each individual unit. This enables accurate positioning and focusing of the laser beam on the buffer layer for precise peeling operations.
Solution Approach 2:
The patent performs the cutting operation before the laser peeling process. This preliminary action of dividing the substrate eliminates warpage-induced positioning errors, ensuring that subsequent laser beam focusing and peeling operations can be performed with high precision.
3Ease of manufacture
If the epitaxy substrate is peeled off without cutting, then the process is simpler, but the optical device layer may be damaged or the buffer layer may not be surely decomposed
Solution Approach 1:
The patent introduces cutting along streets to divide the epitaxy substrate into smaller units before peeling. This segmentation improves peeling reliability by ensuring complete buffer layer decomposition and preventing damage to the optical device layer, while the cutting process itself is straightforward and integrates easily into the existing manufacturing workflow.
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 ensures accurate positioning of the laser beam, reduces damage to the optical device layer, and facilitates smooth peeling of the epitaxy substrate, minimizing adverse effects from N2 gas and improving the transfer process.
Implementation Method 1
applying a laser beam having a transmission wavelength to the epitaxy substrate from the back side of the epitaxy substrate to a unit of the optical device wafer and the transfer substrate in a condition where the focal point of the laser beam is set in the buffer layer, thereby decomposing the buffer layer
Implementation Method 2
warpage occurs in the unit of the epitaxy substrate and the transfer substrate bonded together because of a difference in coefficient of linear expansion between the epitaxy substrate and the transfer substrate
Data Source
AI summary
A wafer processing method transfers an optical device layer (ODL) in an optical device wafer (ODW) to a transfer substrate. The ODL is formed on the front side of an epitaxy substrate through a buffer layer, and is partitioned by a plurality of crossing streets to define a plurality of regions where optical devices are formed. The transfer substrate is bonded to the front side of the ODL. The transfer substrate and the ODL are cut along the streets. The transfer substrate is attached to a supporting member, and a laser beam is applied to the epitaxy substrate from the back side of the epitaxy substrate to the unit of the ODW and the transfer substrate. The focal point of the laser beam is set in the buffer layer, thereby decomposing the buffer layer. The epitaxy substrate is then peeled off from the ODL.