GaN-on-SiC Substrate Reuse via Laser Lift-Off Separation
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Solution Overview
Problem
The challenge lies in finding a semiconductor substrate that balances lattice matching with silicon carbide substrates while reducing the high cost associated with them, particularly for applications in radio frequency (RF) components and power devices, where silicon and gallium nitride exhibit lattice mismatch.
Innovation Solution
A method involving the epitaxial growth of a buffer layer and a silicon carbide layer on a silicon surface of an N-type silicon carbide substrate, followed by a gallium nitride epitaxial layer, with a damaged layer formed using a laser to separate the substrate, allowing for the reuse of silicon carbide substrates and reducing material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicon carbide substrates are used to solve lattice mismatch with gallium nitride, then crystal quality is improved, but substrate cost increases significantly
Solution Approach 1:
The substrate system is segmented into a reusable silicon carbide substrate and a separable semiconductor structure. The damaged layer acts as a separation interface, allowing the expensive silicon carbide substrate to be separated and reused while retaining the gallium nitride epitaxial layer on a cheaper carrier substrate.
Solution Approach 2:
The silicon carbide substrate is temporarily used during epitaxial growth, then separated and recovered for reuse. The damaged layer enables this recovery process by providing a separation plane between the substrate and the grown semiconductor structure.
2Ease of manufacture
If silicon substrates are used to reduce cost, then substrate cost decreases, but lattice mismatch with gallium nitride occurs
Solution Approach 1:
A silicon carbide buffer layer is introduced as an intermediary between the silicon substrate and the gallium nitride epitaxial layer. This buffer layer has lattice parameters closer to gallium nitride, reducing the mismatch effect while allowing the use of cheaper silicon substrates.
3Productivity
If laser lift off layer is added to enable substrate separation, then substrate reuse is enabled, but device complexity increases
Solution Approach 1:
The damaged layer is formed in advance during the epitaxial growth process, creating a predetermined separation plane before the growth is complete. This preliminary action enables subsequent easy separation without requiring complex post-processing.
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 ensures high lattice matching and good crystal quality for RF and power devices while significantly reducing substrate costs by reusing silicon carbide substrates, thereby addressing the cost and lattice mismatch issues.
Implementation Method 1
a laser is used to form a damaged layer in the semiconductor structure after epitaxially growing the gallium nitride epitaxial layer
Implementation Method 2
Epitaxy refers to the technology of growing new crystals on a wafer to form a semiconductor layer
Data Source
AI summary
A semiconductor substrate and a method of manufacturing the same are provided. The method includes epitaxially growing a buffer layer and a silicon carbide layer on a silicon surface of an N-type silicon carbide substrate, and the silicon carbide layer is high-resistivity silicon carbide or N-type silicon carbide (N—SiC). Next, a gallium nitride epitaxial layer is epitaxially grown on the silicon carbide layer to obtain a semiconductor structure composed of the buffer layer, the silicon carbide layer, and the gallium nitride epitaxial layer. After the epitaxial growth of the gallium nitride epitaxial layer, a laser is used to form a damaged layer in the semiconductor structure, and a chip carrier is bonded to the surface of the gallium nitride epitaxial layer, and then the N-type silicon carbide and the semiconductor structure are separated at the location of the damaged layer.