GaN-on-Diamond Wafer Structure for Thin-Wafer Thermal Stability
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Solution Overview
Problem
Conventional methods for manufacturing AlGaN/GaN high electron mobility transistors (HEMTs) on diamond wafers are inconsistent and lack mechanical strength, making them unsuitable for semiconductor processing due to thin wafer thickness and thermal stress issues.
Innovation Solution
A semiconductor wafer structure comprising a substrate wafer, a bonding layer, a diamond layer, an intermediate layer, and a III-Nitride semiconductor layer, where a nucleation layer is disposed on the substrate, and a diamond layer is formed on the semiconductor layer after removing the substrate, with a carrier wafer bonded to a protection layer to enhance mechanical strength and thermal stability.
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 thermal stability deteriorate
Solution Approach 1:
The patent employs a composite structure consisting of a thin AlGaN/GaN HEMT layer (less than 200 μm) bonded to a diamond substrate. The diamond substrate provides the necessary mechanical strength and thermal stability, while the thin semiconductor layer maintains low manufacturing cost. This composite approach allows the thin wafer to withstand thermal and mechanical stresses during semiconductor processing by leveraging the exceptional properties of diamond.
2Ease of manufacture
If the wafer thickness is reduced to less than 200 μm, then the manufacturing cost is reduced, but the thermal stability deteriorates
Solution Approach 1:
The diamond substrate serves as a thermally stable foundation for the thin AlGaN/GaN HEMT layer. Diamond's superior thermal conductivity and stability prevent thermal degradation during semiconductor processing, enabling the use of thin wafers without compromising thermal performance.
Solution Approach 2:
The patent introduces an intermediate layer between the AlGaN/GaN HEMT layer and the diamond substrate to manage thermal stress and ensure stable bonding. This intermediary layer facilitates thermal management and maintains compositional stability during high-temperature processing.
3Ease of manufacture
If the wafer thickness is reduced to less than 200 μm, then the manufacturing cost is reduced, but the reliability deteriorates
Solution Approach 1:
The composite structure of thin semiconductor layer on diamond substrate ensures device reliability by providing mechanical support and thermal management. The diamond substrate's exceptional properties prevent wafer failure during processing and operation, maintaining high reliability despite reduced thickness.
Solution Approach 2:
The intermediate layer acts as a buffer that enhances bonding reliability between the thin semiconductor layer and diamond substrate, ensuring consistent device performance and reducing failure rates during subsequent semiconductor 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
The proposed method enables consistent fabrication of AlGaN/GaN HEMTs with improved mechanical strength and thermal stability, allowing for efficient processing and device formation without the limitations of conventional techniques.
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
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 substrate wafer that includes a glass substrate (or a silicon substrate covered by a protection layer) is glass bonded to the diamond layer. Then, the silicon carrier wafer and the protection layer are removed.