Indium Phosphide Substrate Back-Surface Flatness for Uniform Epitaxy
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Solution Overview
Problem
The indium phosphide substrate exhibits significant warpage during epitaxial growth due to non-uniform contact with the susceptor, leading to uneven heat conduction and substrate temperature, which deteriorates the quality of the epitaxial crystal layer and affects semiconductor performance.
Innovation Solution
A method to produce an indium phosphide substrate with a back surface SORI value of 2.5 µm or less, achieved through precise cutting, etching, and polishing processes, ensuring uniform contact with the susceptor and consistent heat distribution during epitaxial growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical polishing is performed to improve surface flatness, then surface quality is improved, but warpage of the back surface increases
Solution Approach 1:
The patent divides the polishing process into two distinct stages: (1) rough polishing to remove polishing debris and damage layers, and (2) precision polishing to achieve the required surface flatness. This segmentation allows each stage to be optimized independently, preventing excessive warpage while achieving the required surface quality.
Solution Approach 2:
The patent performs etching before polishing to remove the damage layer and polishing debris in advance. This preliminary action prevents the need for excessive polishing that would otherwise be required to remove damaged material, thereby reducing back surface warpage while still achieving the required surface quality.
2Manufacturing precision
If back surface warpage is reduced to improve heat conduction uniformity, then epitaxial crystal layer quality is improved, but manufacturing complexity increases
Solution Approach 1:
The patent controls the SORI value (a quantitative measure of back surface warpage) to be within a specific range (not exceeding a predetermined value). By establishing clear parameter specifications and control limits, the patent achieves uniform heat conduction without requiring overly complex manufacturing processes.
Solution Approach 2:
The patent implements measurement and control of the SORI value to monitor and adjust back surface flatness during manufacturing. This feedback mechanism ensures that warpage remains within acceptable limits, achieving uniform heat conduction through controlled adjustment rather than complex process design.
3Shape
If multiple polishing and etching steps are performed to reduce warpage, then back surface flatness is improved, but production time increases
Solution Approach 1:
The patent combines rough polishing and precision polishing into a coordinated two-stage process, and integrates etching steps with polishing operations. This merging of operations achieves the required back surface flatness while minimizing the total number of separate process steps, thereby maintaining production efficiency.
Solution Approach 2:
The patent implements a continuous manufacturing flow where polishing and etching operations are sequentially arranged without unnecessary interruptions. This continuous action approach reduces idle time between operations, achieving high back surface flatness while maintaining high production efficiency.
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 suppresses warpage of the substrate's back surface, ensuring uniform heat conduction and improved quality of the epitaxial crystal layer, thereby enhancing the performance of semiconductor epitaxial wafers.
Implementation Method 1
cutting a wafer from an indium phosphide ingot with a wire saw
Implementation Method 2
etching the cut wafer
Implementation Method 3
polishing at least one surface of the chamfered wafer
Implementation Method 4
uniform heat conduction to the substrate
Implementation Method 5
A main surface of the indium phosphide substrate may be provided with an epitaxial crystal layer by epitaxial growth
Data Source
AI summary
Provided is an indium phosphide substrate, a semiconductor epitaxial wafer, and a method for producing an indium phosphide substrate, which can satisfactorily suppress warpage of the back surface of the substrate. The indium phosphide substrate includes a main surface for forming an epitaxial crystal layer and a back surface opposite to the main surface, wherein the back surface has a SORI value of 2.5 µm or less, as measured with the back surface of the indium phosphide substrate facing upward.