Indium Phosphide Wafer Edge Smoothing for Crack Suppression
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Solution Overview
Problem
Indium phosphide substrates are prone to cracking due to large surface roughness at the edges, caused by edge irregularities and processing damage during manufacturing and shipment.
Innovation Solution
The indium phosphide substrate is manufactured with a surface roughness of the edge part controlled to a maximum height of 2.1 μm or less and a root mean square height of 0.15 μm or less, achieved through chamfering and polishing with a #4000 grit size polishing film, followed by etching, to suppress cracking and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional chamfering with #800 or #1200 grindstone is used, then edge machining is completed, but large surface roughness causes substrates to crack easily
Solution Approach 1:
The patent changes the grit size parameter of the polishing film from conventional #800 or #1200 to #4000, which fundamentally alters the surface roughness characteristics of the chamfered edge. This parameter change reduces the maximum height Sz to 2.1 μm or less and root mean square height Sq to 0.15 μm or less, thereby preventing substrate cracking while maintaining manufacturing feasibility
Solution Approach 2:
The patent replaces the conventional mechanical grinding process with a chemical etching process after polishing. This substitution allows for more precise control of surface properties and removes processing damage layers that mechanical grinding cannot eliminate, significantly improving substrate reliability
2Manufacturing precision
If mechanical polishing is performed to remove polishing debris and damage, then surface quality improves, but processing damage and edge irregularities remain
Solution Approach 1:
The patent introduces a chemical etching process as an intermediary step between mechanical polishing and final surface completion. This etching process acts as a mediator that removes processing damage and irregularities created by mechanical polishing without introducing new mechanical stress, achieving superior surface quality with minimal harmful factors
Solution Approach 2:
The patent changes the surface treatment approach from purely mechanical to a combination of mechanical polishing followed by chemical etching. This parameter change in the processing method allows for removal of processing damage while controlling surface roughness within specific ranges (Sz ≤ 2.1 μm, Sq ≤ 0.15 μm)
3Reliability
If edge polishing is performed to reduce surface roughness, then cracking is suppressed, but contamination and residue migration may occur
Solution Approach 1:
The patent optimizes the polishing film grit size to #4000, which provides the right balance between reducing surface roughness (Sz ≤ 2.1 μm, Sq ≤ 0.15 μm) for crack suppression and maintaining surface cleanliness. This specific parameter choice prevents excessive material removal that could generate contamination while achieving sufficient smoothness
Solution Approach 2:
The patent replaces continued mechanical polishing with chemical etching to achieve the final surface finish. This substitution eliminates the risk of contamination and residue migration associated with mechanical polishing while maintaining crack suppression through controlled surface roughness reduction
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 effectively reduces cracking and contamination, improving the surface quality and yield of indium phosphide substrates by ensuring precise edge smoothing and preventing residue migration.
Implementation Method 1
a surface roughness of an edge part of the substrate has a maximum height Sz of 2.1 μm or less, as measured by a laser microscopy on the entire surface of the edge part
Implementation Method 2
a process of polishing the entire surface of the edge part of the indium phosphide wafer after the chamfering with a polishing film of #4000 grit size
Implementation Method 3
a process of etching the indium phosphide wafer after polishing the edge part of the indium phosphide wafer
Data Source
AI summary
Provided is an indium phosphide substrate, a method for manufacturing indium phosphide substrate, and a semiconductor epitaxial wafer capable of suppressing cracks in indium phosphide substrates caused by edge irregularities and processing damage. An indium phosphide substrate, wherein a surface roughness of an edge part of the substrate has a maximum height Sz of 2.1 μm or less, as measured by a laser microscopy on the entire surface of the edge part.