GaN Bonding Layer Formation After Laser Lift-Off
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Solution Overview
Problem
Existing semiconductor manufacturing processes using laser lift-off techniques result in irregularities on the GaN surface, requiring a polishing process that decreases productivity, and the use of materials different from the semiconductor layer for bonding further reduces productivity.
Innovation Solution
A method involving a laser lift-off process where a low melting point layer formed from the semiconductor layer is used to bond the substrate and semiconductor layer, eliminating the need for polishing and using materials different from the semiconductor layer for bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a laser lift-off process is used to separate the GaN layer from the sapphire substrate, then the GaN layer can be separated, but irregularities are formed on the GaN surface requiring a polishing process that decreases productivity
Solution Approach 1:
The patent extracts and utilizes the gallium material separated during laser lift-off to form the bonding layer, rather than removing it as a defect. This converts the harmful irregularities into a useful bonding medium, eliminating the need for polishing while maintaining productivity
Solution Approach 2:
The gallium-based bonding layer acts as an intermediary between the GaN layer and the substrate, filling surface irregularities and providing a bonding interface that eliminates the need for additional polishing steps
2Strength
If a material different from the semiconductor layer such as an adhesive is adopted as a bonding layer, then bonding can be achieved, but productivity decreases
Solution Approach 1:
The patent uses gallium, a constituent element of the GaN semiconductor layer, to form the bonding layer. This homogeneous material approach eliminates the need for separate adhesive materials and simplifies the manufacturing process, improving productivity while maintaining bonding strength
Solution Approach 2:
The gallium-based bonding layer serves multiple functions: it acts as both the bonding agent and fills surface irregularities. This multi-functionality eliminates the need for separate polishing and bonding steps, improving productivity
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
Improves productivity by reducing the number of manufacturing steps and lowering material costs while enhancing bonding strength and area, resulting in a more efficient semiconductor device.
Implementation Method 1
injecting a laser into a gallium nitride (GaN) layer grown on the sapphire substrate
Implementation Method 2
GaN is separated into gallium (Ga: liquid or solid) and nitrogen (N2) gas at the boundary portion
Implementation Method 3
forming the bonding layer that bonds the first substrate and the semiconductor layer to each other by reacting a product formed on a bonded surface of the semiconductor layer by irradiation of the laser
Data Source
AI summary
A semiconductor device includes a first substrate, a semiconductor layer consisting of a nitride-based compound semiconductor, and a bonding layer bonded to the first substrate and the semiconductor layer between the first substrate and the semiconductor layer, and containing at least one of constituent elements of the nitride-based compound semiconductor.