SiC Composite Transfer Substrate for Warpage-Stable Bonding
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Solution Overview
Problem
The existing methods for manufacturing SiC single-crystalline substrates face challenges such as high process temperatures, difficulty in controlling crystal growth and defects, and the resulting high cost of high-quality SiC substrates, which hinders their widespread use in electronic devices.
Innovation Solution
A composite substrate is developed by directly bonding a SiC single-crystalline substrate to a first SiC polycrystalline substrate with a volume resistivity of 10 Ω·cm or less, using a fast atomic beam for surface activation and normal temperature bonding, which allows for the transfer of a SiC single-crystalline thin film to a support substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a SiC single-crystalline substrate is repeatedly used for manufacturing SiC bonded substrates, then the manufacturing efficiency is improved, but the warpage of the substrate increases due to thinning
Solution Approach 1:
The patent applies the nesting principle by bonding a thin SiC single-crystalline substrate to a thicker SiC polycrystalline substrate, creating a composite structure where the thin substrate is supported by the thicker substrate. This prevents warpage of the thin substrate during repeated use while maintaining the ability to manufacture multiple bonded substrates efficiently.
2Manufacturing precision
If the thickness of SiC single-crystalline substrate is reduced to improve transfer efficiency, then the manufacturing precision is improved, but the substrate becomes more susceptible to warpage and handling errors
Solution Approach 1:
The thin SiC single-crystalline substrate is nested on the SiC polycrystalline substrate, providing mechanical support that prevents warpage and handling errors while maintaining the thin thickness needed for precise transfer and bonding operations.
Solution Approach 2:
The SiC polycrystalline substrate acts as an intermediary support that provides mechanical stability to the thin SiC single-crystalline substrate, enabling easy handling and precise positioning during the bonding process without requiring the substrate to be thicker.
3Device complexity
If conventional bonding methods are used without surface activation, then the device complexity is reduced, but the bonding strength is insufficient and bonding defects occur
Solution Approach 1:
The patent applies preliminary action by performing surface activation treatment on the bonding surfaces of both substrates before bonding. This preliminary step removes oxide films and activates the surfaces to enhance bonding strength and prevent bonding defects, ensuring reliable covalent bonding.
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 improves the warpage of repeatedly used SiC single-crystalline substrates, enabling better handling and reducing bonding defects, thus enhancing the manufacturing efficiency and reducing costs of SiC bonded substrates.
Implementation Method 1
a first activation step of irradiating a first bonding target surface of the SiC single-crystalline substrate and a bonding target surface of the first SiC polycrystalline substrate with a fast atomic beam to activate these bonding target surfaces
Implementation Method 2
the SiC single-crystalline substrate and the SiC polycrystalline substrate are held by an electrostatic chuck
Data Source
Figure 1
Figure 2~3
Figure 4(a)~4(d)
AI summary
Provided are: a composite substrate for transferring a SiC single crystal; a method for manufacturing the composite substrate for transferring a SiC single crystal; and a method for manufacturing a SiC bonded substrate, in which warpage in a SiC single-crystalline substrate repeatedly used in a process for manufacturing a SiC bonded substrate is improved such that errors in conveying the SiC single-crystalline substrate or a problem of not being able to hold the SiC single-crystalline substrates on a processing table can be suppressed, the SiC single-crystalline substrate can be held on the processing table using an electrostatic chuck during a surface activation step or a bonding step, and the occurrence of bonding defects can be suppressed. A composite substrate for transferring a SiC single crystal includes a SiC single-crystalline substrate and a first SiC polycrystalline substrate having a volume resistivity of 10 Ω·cm or less, in which one surface of the SiC single-crystalline substrate is directly bonded to one surface of the first SiC polycrystalline substrate by covalent bonds.