Laser Peeling for SiC Substrate Removal
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Solution Overview
Problem
The existing methods for removing a low-resistance polycrystalline SiC substrate from a two-layer structure semiconductor substrate are inefficient, requiring a significant amount of time and resulting in poor productivity.
Innovation Solution
A semiconductor substrate processing method involving the formation of a peeling layer using a laser beam with a wavelength capable of passing through the substrate, followed by epitaxial growth of a second semiconductor substrate, peeling off the first substrate using the peeling layer as a starting point, and subsequent grinding to efficiently remove the first substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the low-resistance polycrystalline SiC substrate is removed by grinding, then the substrate can be separated from the two-layer structure, but the process takes a considerable time resulting in poor productivity
Solution Approach 1:
The invention forms a peeling layer at a shallow position from the upper surface of the first semiconductor substrate before the grinding step. This preliminary action creates a starting point for peeling that allows most of the first substrate to be removed quickly through peeling, significantly reducing the subsequent grinding time and improving productivity
Solution Approach 2:
The invention divides the substrate removal process into two distinct stages: peeling (removing most of the first substrate using the peeling layer as a starting point) and grinding (removing the remaining thin layer). This segmentation allows each process to be optimized independently, with peeling handling the bulk removal and grinding handling the final precision removal
2Productivity
If a peeling layer is formed at a shallow position from the upper surface, then most of the first substrate can be peeled off efficiently, but the laser beam must pass through the substrate to reach the focal point
Solution Approach 1:
The invention selects a specific wavelength for the laser beam that is capable of passing through the first semiconductor substrate. By changing the wavelength parameter to match the transmission characteristics of the substrate material, the laser energy can reach the focal point positioned within the substrate to form the peeling layer at the desired shallow position
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 method significantly shortens the time required for grinding and enhances productivity by allowing most of the first semiconductor substrate to be peeled off using the peeling layer, even when dealing with hard materials like low-resistance polycrystalline SiC.
Implementation Method 1
forming a peeling layer by irradiating a first semiconductor substrate with a laser beam having a wavelength capable of passing through the first semiconductor substrate while positioning a focal point of the laser beam within the first semiconductor substrate
Implementation Method 2
forming a peeling layer by irradiating a first semiconductor substrate with a laser beam
Implementation Method 3
forming a second semiconductor substrate by epitaxial growth on an upper surface of the first semiconductor substrate
Data Source
AI summary
A semiconductor substrate processing method includes: a peeling layer forming step of forming a peeling layer by irradiating a first semiconductor substrate with a laser beam having a wavelength capable of passing through the first semiconductor substrate while positioning a focal point of the laser beam within the first semiconductor substrate; a second semiconductor substrate forming step of forming a second semiconductor substrate by epitaxial growth on an upper surface of the first semiconductor substrate after performing the peeling layer forming step; a peeling step of peeling off the first semiconductor substrate from the peeling layer; and a grinding step of grinding and removing the first semiconductor substrate after performing the peeling step.