Nitride Wafer Chamfering with Soft Rubber Whetstone
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Solution Overview
Problem
Current chamfering methods for nitride semiconductor wafers, such as GaN, are prone to cracking and breaking due to the high rigidity and fragility of these materials, and existing techniques like resin- or metal-bonding whetstones induce excessive mechanical stress, leading to thick process-induced degradation layers and bow issues.
Innovation Solution
Employing a soft bonding material like rubber or bubbled resin with fine diamond granules and oxide granules to create a mechanochemical effect, reducing mechanical shock and controlling the edge process-induced degradation layer thickness to 0.5 μm-10 μm, thereby preventing cracks and bow, and enhancing device production yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional resin- or metal-bonding whetstones are used for chamfering nitride wafers, then the chamfering process can be performed, but the high rigidity and fragility of nitride materials cause cracking and breaking
Solution Approach 1:
The patent changes the bonding material parameter from hard resin or metal to soft rubber, and changes the granule size parameter from coarse to fine (10-200 mesh). This parameter transformation allows the chamfering process to proceed while the soft bonding material absorbs mechanical shocks, preventing cracks and breaks in the fragile nitride wafer edges.
Solution Approach 2:
The patent uses a composite structure combining soft rubber bonding material with fine diamond or abrasive granules. This composite whetstone configuration provides both the mechanical cutting ability from the granules and the shock-absorbing properties from the soft rubber matrix, resolving the contradiction between manufacturability and reliability.
2Ease of manufacture
If conventional whetstones are used for chamfering, then edges can be processed, but thick process-induced degradation layers are formed causing bow issues
Solution Approach 1:
The patent changes the granule size parameter to fine (10-200 mesh) and the bonding material to soft rubber, which together produce a thin process-induced degradation layer (0.5-5 μm) instead of the thick layer caused by conventional whetstones. This thin layer minimizes bow while still achieving effective edge processing.
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 method effectively prevents cracking and breaking of nitride wafers during chamfering, reduces the thickness of process-induced degradation layers, minimizes bow, and increases the yield of device production by using a soft whetstone with fine diamond and oxide granules, ensuring a smooth and scar-free edge.
Implementation Method 1
Employing a soft bonding material like rubber or bubbled resin with fine diamond granules and oxide granules to create a mechanochemical effect, reducing mechanical shock
Implementation Method 2
fine diamond granules and oxide granules to create a mechanochemical effect
Data Source
AI summary
A nitride semiconductor wafer is planar-processed by grinding a bottom surface of the wafer, etching the bottom surface by, e.g., KOH for removing a bottom process-induced degradation layer, chamfering by a rubber whetstone bonded with 100 wt %-60 wt % #3000-#600 diamond granules and 0 wt %-40 wt % oxide granules, grinding and polishing a top surface of the wafer, etching the top surface for eliminating a top process-induced degradation layer and maintaining a 0.5 μm-10 μm thick edge process-induced degradation layer.