Backside Heat Dissipation Structure for SOI RF Transistors
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Solution Overview
Problem
Semiconductor-on-insulator (SOI) substrates used in RF devices face challenges with low resistivity, leading to overheating issues that deteriorate the efficiency of RF devices, especially with the advent of 5G cellular mobile communication.
Innovation Solution
A heat dissipation structure is implemented using a metal structure or conductive pads on the wafer backside, which includes a first device wafer with a transistor, source/drain doping regions, and a channel region, where a dummy metal structure or conductive pads are formed to contact the backside and overlap the channel region, facilitating thermal conduction without affecting the semiconductor device properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resistivity of the substrate is increased to improve RF device efficiency, then the efficiency of RF devices is improved, but the temperature of the substrate becomes too high causing deterioration of RF device efficiency
Solution Approach 1:
The substrate is segmented into functional regions: a high-resistivity substrate region for RF device operation and a separate heat dissipation region with metal structures. This segmentation allows the substrate to maintain high resistivity for improved RF efficiency while the metal structures handle thermal dissipation independently.
Solution Approach 2:
Metal structures (such as dummy metal layers or conductive pads) are introduced as intermediary elements between the RF devices and the substrate. These metal structures serve as thermal conduits that conduct heat away from the high-resistivity substrate region without interfering with the electrical properties of the RF devices.
2Temperature
If a metal structure is added to dissipate heat, then heat dissipation capability is improved, but the device complexity increases
Solution Approach 1:
The metal structures are designed to serve multiple functions: they act as heat dissipation elements during normal operation and can serve as dummy structures to maintain layout symmetry or as conductive pads for electrical connections. This multi-functionality reduces the need for separate dedicated heat dissipation components.
Solution Approach 2:
The resistivity parameter of the substrate is changed to high values to improve RF device efficiency. This parameter change is localized to specific regions, allowing other regions to maintain different properties optimized for heat dissipation, thus managing complexity through selective parameter optimization.
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 solution effectively increases the resistivity of the substrate, enhancing the efficiency of RF devices while preventing overheating by utilizing the high thermal conductivity of metals for heat dissipation without overlapping the device region.
Implementation Method 1
utilizing the high thermal conductivity of metals for heat dissipation
Data Source
AI summary
A semiconductor structure with a heat dissipation structure includes a first device wafer includes a front side and a back side. A first transistor is disposed on the front side. The first transistor includes a first gate structure disposed on the front side. Two first source/drain doping regions are embedded within the first device wafer at two side of the first gate structure. A channel region is disposed between the two first source/drain doping regions and embedded within the first device wafer. A first dummy metal structure contacts the back side of the first device wafer, and overlaps the channel region.