GaN Substrate Manufacturing via Buffer and Separation Layers
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Solution Overview
Problem
Current methods for manufacturing high-quality GaN single crystal substrates are costly and have low yield due to the need for heterogeneous substrates and complex separation processes, which result in high manufacturing costs and reduced productivity.
Innovation Solution
A method involving the formation of a buffer layer and a separation layer on a base substrate, followed by growing a semiconductor layer at multiple temperatures and separating it from the base substrate via cooling, using source gases like NH3 and HCl to form a GaN layer, simplifying the process and improving surface properties and crystallinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a heterogeneous substrate is used to grow GaN layer, then the GaN layer can be grown on available substrates, but the lattice mismatch and thermal expansion coefficient mismatch cause high defect density and low quality
Solution Approach 1:
The patent introduces a buffer layer as an intermediary between the heterogeneous substrate and the GaN layer. This buffer layer acts as a mediator that reduces the lattice mismatch and thermal expansion coefficient mismatch, enabling high-quality GaN layer growth on available heterogeneous substrates without requiring direct growth on expensive GaN single crystal substrates.
2Ease of manufacture
If laser lift-off or wet etching is used to separate GaN substrate from heterogeneous substrate, then separation can be achieved, but the process complexity and manufacturing cost increase
Solution Approach 1:
The patent introduces a separation layer during the initial growth process that is specifically designed to facilitate automatic separation later. This preliminary action of creating a weakly bonded separation layer during growth eliminates the need for complex post-growth separation processes like laser lift-off or wet etching, as the layers can be separated automatically by simple mechanical means or thermal cycling.
3Productivity
If automatic separation by cooling is used, then separation can be achieved without additional processing steps, but the yield is low and manufacturing cost is high
Solution Approach 1:
The patent applies local quality by creating a separation layer with specific local properties (weak bonding) at the interface between the GaN layer and the heterogeneous substrate. This localized weak bonding region allows for reliable and consistent separation without affecting the quality of the GaN layer itself, thereby improving manufacturing yield while maintaining process simplicity.
4Manufacturing precision
If high-quality GaN single crystal substrate is used, then high-quality GaN thin film can be grown, but the substrate cost is extremely high and availability is limited
Solution Approach 1:
The patent uses a buffer layer as an intermediary that enables high-quality GaN thin film growth on inexpensive, readily available heterogeneous substrates. This buffer layer mediates the interface between the cheap substrate and the high-quality GaN film, allowing the film to achieve single-crystal quality without requiring expensive GaN single crystal substrates.
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 reduces manufacturing costs and improves productivity by simplifying the process, achieving high-quality semiconductor substrates with excellent surface properties and crystallinity, and enabling the automatic separation of GaN substrates from heterogeneous substrates.
Implementation Method 1
forming a buffer layer on the base substrate; The buffer layer may be formed by nitriding the base substrate using NH3 gas
Implementation Method 2
forming a separation layer on the buffer layer; The separation layer may be formed of NH4Cl using NH3 and HCl
Implementation Method 3
forming a semiconductor layer on the separation layer at least two temperatures; forming a GaN layer through a reaction between GaCl and NH3
Implementation Method 4
separating the semiconductor layer from the base substrate via the separation layer by cooling the base substrate
Data Source
AI summary
The present invention is directed to a method of manufacturing a substrate, which includes loading a base substrate into a reaction furnace; forming a buffer layer on the base substrate; forming a separation layer on the buffer layer; forming a semiconductor layer on the separation layer at least two; and separating the semiconductor layer from the base substrate via the separation layer through natural cooling by unloading the base substrate from the reaction furnace.