Composite Substrate Semiconductor Structure for RF Heat Dissipation
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Solution Overview
Problem
High-frequency semiconductor devices face limitations due to increased loss and self-heating issues in RF front-end modules, particularly in power amplifiers, which restrict available power and size compatibility, and require enhanced heat dissipation capabilities to prevent thermal runaway.
Innovation Solution
A semiconductor device with a substrate structure comprising a first base with higher thermal conductivity and a second base of a compound semiconductor, where the circuit elements and electrodes are disposed on the second base, and a conductor protrusion for external connection is used, allowing heat dissipation through multiple paths, including the first base, to enhance thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single substrate is used for high-frequency circuits, then the device can be simple in structure, but the heat-dissipation capacity is insufficient leading to thermal runaway
Solution Approach 1:
The substrate is divided into a first substrate and a second substrate with different materials. The first substrate provides mechanical support while the second substrate with higher thermal conductivity handles heat dissipation. This segmentation allows each substrate to be optimized for its specific function, resolving the contradiction between structural simplicity and heat-dissipation capacity.
Solution Approach 2:
The invention uses a composite substrate structure combining two different substrate materials. The first substrate and second substrate are bonded together to form a composite structure that leverages the advantages of both materials: mechanical stability from one material and superior thermal conductivity from the other, thereby achieving both structural integrity and enhanced heat dissipation.
2Power
If the power of the power amplifier is increased, then the functionality is improved, but self-heating increases causing thermal runaway
Solution Approach 1:
The second substrate acts as an intermediary heat dissipation layer between the power amplifier circuit and the first substrate. It provides a dedicated thermal conduction path that mediates the heat transfer process, allowing high power operation by efficiently conducting heat away from the active circuit elements before it can cause thermal runaway.
Solution Approach 2:
The invention changes the thermal conductivity parameter of the substrate system by introducing a second substrate with higher thermal conductivity. This parameter change enables the system to handle higher power levels by improving the heat dissipation rate, thereby preventing thermal runaway while maintaining high functionality.
3Volume of moving object
If the size of the MMIC is reduced, then the degree of integration is improved, but the heat-dissipation capacity is further limited
Solution Approach 1:
The second substrate is positioned locally beneath the high-power circuit elements to provide targeted heat dissipation where it is most needed. This local quality approach allows the rest of the device to maintain a compact form factor while critical areas receive enhanced thermal management, resolving the contradiction between miniaturization and heat dissipation.
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 achieves high heat-dissipation capacity, enabling high-power operation while maintaining a compact size, improving RF characteristics and reducing thermal resistance, thus addressing the limitations of self-heating and power compatibility.
Implementation Method 1
The first base has a higher thermal conductivity than the second base
Data Source
AI summary
A semiconductor device includes a substrate, a circuit element disposed on or above the upper surface of the substrate, an electrode disposed on or above the upper surface of the substrate and connected to the circuit element, and a conductor pillar bump for external connection which is disposed on the substrate and electrically connected to the electrode or the circuit element. The substrate includes a first base and a second base disposed on the first base. The circuit element and the electrode are disposed on the second base. The first base has lower thermal resistance than the second base.