Micro-Transfer Printed GaN-on-SOI RF Circuit for Leakage Control
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Solution Overview
Problem
Existing technologies face challenges in achieving high linearity, high power handling, low noise figure, and low power consumption in Monolithic Microwave Integrated Circuit (MMIC) circuitry, which are often antagonistic requirements.
Innovation Solution
The integration of GaN and SOI technologies using micro-transfer printing (μTP) allows for monolithic designs with enhanced RF circuit performance, combining the advantages of both technologies to achieve improved noise figure, isolation, and power handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If GaN transistors are grown directly on SOI substrate using trench etching, then integration of GaN and SOI advantages is achieved, but manufacturing complexity and strain control difficulty increase
Solution Approach 1:
The invention segments the GaN device fabrication process into two independent stages: first growing GaN on a sacrificial Si substrate, then transferring to the SOI target substrate. This segmentation avoids the complexity of direct growth on SOI while achieving the desired integration.
Solution Approach 2:
The sacrificial silicon substrate acts as an intermediary medium that enables GaN growth with relaxed strain conditions, followed by transfer to the final SOI substrate. This intermediary approach simplifies the overall manufacturing process compared to direct growth.
2Device complexity
If micro-transfer printing is used to transfer GaN device from native wafer to SOI wafer, then manufacturing complexity is reduced, but vertical leakage increases
Solution Approach 1:
The invention extracts and removes the problematic native silicon substrate through sacrificial layer dissolution, taking out the source of vertical leakage paths while transferring the GaN device to the clean SOI substrate where such leakage paths are eliminated.
Solution Approach 2:
The sacrificial silicon substrate, which could be seen as adding complexity, is actually used beneficially to enable relaxed-strain GaN growth. After serving its purpose during fabrication, it is completely removed to eliminate vertical leakage, converting a potential harm into a manufacturing benefit.
3Ease of manufacture
If GaN is grown on Si substrate, then cost is reduced compared to SiC, but thermal performance and RF losses worsen
Solution Approach 1:
The invention separates the growth substrate dimension from the final device substrate dimension. GaN is grown on inexpensive Si for cost benefits, then transferred to SOI substrate that provides superior thermal and RF performance, effectively using different substrates for different functional requirements.
Data Source
AI summary
A semiconductor structure for RF applications comprises: a first μTP GaN transistor on an SOI wafer or die; and a first resistor connected to the gate of said first transistor.