Silicon Carbide Substrate Thinning via Anodized Weakened Layers
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Solution Overview
Problem
Silicon carbide substrates are difficult to thin due to their high hardness, leading to microcracks, material fragmentation, and warping during conventional grinding processes, which often require expensive diamond abrasive particles and introduce high stress.
Innovation Solution
Anodization is used to convert a predetermined reaction part of the substrate into a weakened layer with a controlled thickness, followed by removal methods like grinding, ultrasonic oscillation, or laser ablation, exploiting the difference in material strength between the weakened and solid parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If diamond abrasive particles are used to thin silicon carbide substrate, then the substrate can be thinned, but the cost increases significantly
Solution Approach 1:
The patent replaces the mechanical grinding system with diamond abrasives with an electrochemical system using anodization. The anodization process uses electrochemical reactions to convert silicon carbide into a weakened layer that can be easily removed, substituting mechanical force with electrochemical transformation to achieve substrate thinning at lower cost.
Solution Approach 2:
The patent changes the physical and chemical parameters of the substrate surface through controlled anodization. By adjusting electrochemical parameters such as current density, electrolyte composition, and processing time, the substrate is transformed into a weakened layer with different properties that can be selectively removed without requiring expensive diamond abrasives.
2Manufacturing precision
If hard cutting process is used to thin silicon carbide substrate, then the substrate can be thinned, but microcracks and material fragmentation occur
Solution Approach 1:
The patent replaces mechanical cutting and grinding processes with electrochemical anodization. This substitution eliminates the high-stress mechanical contact that causes microcracks and fragmentation, using instead a chemical transformation process that uniformly converts the substrate material into a weakened layer without introducing mechanical damage.
Solution Approach 2:
The patent performs preliminary electrochemical treatment to create a weakened layer before final substrate thinning. This preliminary action of anodization prepares the substrate by creating a controlled weakened structure that can be easily removed without causing damage to the remaining substrate, ensuring integrity throughout the process.
3Manufacturing precision
If conventional grinding is used on silicon carbide substrate, then the substrate can be thinned, but high residual stress causes wafer warping
Solution Approach 1:
The patent replaces conventional mechanical grinding with electrochemical anodization followed by weakened layer removal. This substitution eliminates the high residual stresses generated by mechanical grinding, as the electrochemical process uniformly transforms the substrate material without creating the compressive and tensile stress gradients that lead to wafer warping.
Solution Approach 2:
The patent performs preliminary anodization to create a weakened layer that is then selectively removed. This two-step process allows controlled material removal without the high-stress conditions of conventional grinding, preventing the generation of residual stresses that would cause warping and maintaining wafer flatness.
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 allows for precise thinning of silicon carbide substrates without cracking or warping, using electrochemical anodization to create a porous or lamellar weakened layer that can be easily removed, maintaining the integrity of the solid substrate.
Implementation Method 1
performing an anodization reaction on the predetermined reaction part by an electrochemical method to convert the predetermined reaction part into a weakened layer
Implementation Method 2
the weakened layer is removed by an ultrasonic oscillation method
Implementation Method 3
the weakened layer is removed by a laser ablation method
Data Source
AI summary
A substrate processing method includes providing a substrate, wherein the substrate has a surface and a bottom surface opposite to each other, the substrate is defined with a predetermined area, the predetermined area is defined with a predetermined reaction part, and the predetermined reaction part extends from the surface toward the bottom surface of the substrate; performing a anodization reaction on the predetermined reaction part by an electrochemical method to convert the predetermined reaction part into a weakened layer, wherein the weakened layer has a thickness; and removing the weakened layer so that the substrate in the predetermined area has an exposed surface.