GaN Diamond Wafer Structure for Thin-Wafer HEMT Processing
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Solution Overview
Problem
Conventional methods for manufacturing AlGaN/GaN high electron mobility transistors (HEMTs) on diamond substrates face challenges due to thin wafer thickness and mechanical strength issues, making it difficult to consistently produce wafers suitable for semiconductor processing equipment and handling.
Innovation Solution
A semiconductor wafer structure comprising a support wafer, a diamond layer, an intermediate layer, and at least one semiconductor layer including a III-Nitride compound, where a nucleation layer is disposed on a substrate, followed by a protection layer, bonding with a carrier wafer, removing the substrate, and depositing a diamond layer, with additional metal layers and processing steps to enhance mechanical strength and thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the wafer thickness is reduced to less than 200 μm, then the manufacturing cost is reduced, but the mechanical strength and ability to withstand thermal and mechanical stresses deteriorates
Solution Approach 1:
The patent employs a composite structure consisting of a diamond layer bonded to a carrier wafer. The diamond layer provides the thin, low-cost semiconductor substrate, while the carrier wafer supplies the necessary mechanical strength and thermal stability. This composite approach allows the semiconductor device to function with thin dimensions while relying on the carrier wafer for structural integrity during processing.
Solution Approach 2:
The patent separates the functional requirements into distinct components: the diamond layer serves as the semiconductor substrate for device fabrication, while the carrier wafer provides mechanical support. This segmentation allows each component to be optimized independently - the diamond layer can be made thin for cost efficiency while the carrier wafer maintains the required mechanical strength.
2Ease of manufacture
If the wafer thickness is reduced to less than 200 μm, then the manufacturing cost is reduced, but the ability to meet robot arm handling requirements deteriorates
Solution Approach 1:
The composite structure of diamond layer on carrier wafer allows the overall assembly to meet the minimum thickness requirement for robot arm handling while keeping the functional semiconductor layer thin. The carrier wafer adds the necessary thickness without interfering with the semiconductor device functionality.
3Ease of manufacture
If diamond layer is deposited directly on AlGaN/GaN HEMT layer, then manufacturing cost is reduced, but consistency and reliability of device production deteriorates
Solution Approach 1:
The carrier wafer is prepared in advance with appropriate mechanical and thermal properties before the diamond layer and semiconductor layers are deposited. This preliminary preparation ensures that the substrate can withstand subsequent processing steps consistently, improving reliability while maintaining cost efficiency.
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
The proposed method enables the fabrication of semiconductor wafers with improved mechanical strength and thermal conductivity, allowing for consistent and reliable processing of AlGaN/GaN HEMTs, addressing the limitations of conventional techniques by providing a robust and thermally stable substrate for semiconductor devices.
Implementation Method 1
Diamond is known to have a good thermal conductivity and can be used as material for a substrate on which the AlGaN/GaN layer is formed
Implementation Method 2
bonding a carrier wafer to the protection layer
Data Source
AI summary
Wafers including a diamond layer and a semiconductor layer having III-Nitride compounds and methods for fabricating the wafers are provided. A nucleation layer, at least one semiconductor layer having III-Nitride compound and a protection layer are formed on a silicon substrate. Then, a silicon carrier wafer is glass bonded to the protection layer. Subsequently the silicon substrate, nucleation layer and a portion of the semiconductor layer are removed. Then, an intermediate layer, a seed layer and a diamond layer are sequentially deposited on the III-Nitride layer. Next, a support wafer that includes a GaN layer (or a silicon layer covered by a protection layer) is deposited on the diamond layer. Then, the silicon carrier wafer and the protection layer are removed.