Backside Heat Dissipation Structure for High-Resistivity RF Wafers
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Solution Overview
Problem
Semiconductor-on-insulator (SOI) substrates used in RF devices face overheating due to insufficient resistivity, which degrades 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, where a metal structure is embedded in a high resistivity wafer to dissipate heat without overlapping the device region, and conductive pads are formed on the backside to enhance heat conduction, utilizing materials like copper, aluminum, or tungsten for effective thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resistivity of the substrate is increased to improve RF device performance, then the efficiency of RF devices is improved, but the temperature of the substrate becomes too high and deteriorates the efficiency of the RF devices
Solution Approach 1:
The patent introduces a heat dissipation structure on the backside of the substrate, moving the heat management function to a different spatial dimension (backside vs. frontside where RF devices are located). This allows heat dissipation without interfering with the RF device operation on the frontside, effectively managing the thermal issue while maintaining high substrate resistivity for improved RF performance.
Solution Approach 2:
The heat dissipation structure acts as an intermediary element between the RF devices and the substrate. It mediates the thermal management by providing a dedicated pathway for heat dissipation on the backside, preventing direct thermal interference between the high-resistivity substrate and the RF devices, thus resolving the contradiction between high resistivity and temperature control.
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 heat dissipation structure is segmented into discrete metal patterns on the backside of the substrate, rather than using a continuous metal layer. This segmentation allows for targeted heat dissipation in specific regions while leaving other areas untouched, reducing overall material usage and structural complexity while maintaining effective heat management.
Solution Approach 2:
The metal heat dissipation structures are placed locally on the backside of the substrate in specific patterns that correspond to heat-generating regions. This local placement provides heat dissipation exactly where needed without adding unnecessary metal structures elsewhere, thereby improving heat dissipation capability while minimizing the increase in device complexity.
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 solution effectively increases the efficiency of RF devices by managing heat generated due to high resistivity, preventing overheating and maintaining the semiconductor device's properties without interference from the heat dissipation structures.
Implementation Method 1
A heat dissipation structure is implemented using a metal structure or conductive pads on the wafer backside, where a metal structure is embedded in a high resistivity wafer to dissipate heat
Implementation Method 2
conductive pads are formed on the backside to enhance heat conduction
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.