Vertical MOSFET Drain Electrode Structure for Better Heat Dissipation
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Solution Overview
Problem
The resistances of a vertical metal oxide semiconductor field effect transistor (MOSFET) in semiconductor devices, including substrate resistance and drain electrode resistance, affect heat dissipation paths, leading to inefficiencies in thermal management and potential reliability issues.
Innovation Solution
The semiconductor device design includes a first electrode with a protruding or recessed structure in the substrate, combined with a bonding layer thickness optimization, to create efficient heat dissipation paths while maintaining bonding strength, using materials with high thermal conductivity like copper and optimized metal layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the drain electrode is designed with a simple planar structure, then the manufacturing process is simple, but the heat dissipation efficiency is insufficient
Solution Approach 1:
The drain electrode is designed with a protrusion extending in the thickness direction (Z-axis) from the substrate surface, transforming a planar 2D structure into a 3D structure. This dimensional change increases the heat dissipation surface area and creates a direct thermal conduction path from the high-heat-generation region (drain region) to the external environment, thereby improving heat dissipation efficiency without significantly complicating the manufacturing process
Solution Approach 2:
The protrusion of the drain electrode is formed in advance during the substrate processing stage, before the bonding to the support substrate. This preliminary formation of the heat dissipation structure allows subsequent bonding processes to proceed without additional complexity, as the thermal conduction path is already established in the initial substrate structure
2Reliability
If the bonding layer is made thicker to ensure bonding strength, then the bonding reliability is improved, but the heat dissipation efficiency is reduced
Solution Approach 1:
The bonding layer thickness is optimized to a specific range (50-200 nm) to achieve the minimum necessary bonding strength while minimizing thermal resistance. This local optimization of the bonding layer thickness allows the system to maintain structural integrity (bonding reliability) while simultaneously enabling efficient heat conduction through the bonding interface, resolving the trade-off between bonding strength and heat dissipation
Solution Approach 2:
The bonding layer thickness parameter is precisely controlled within a specific range (50-200 nm) rather than using a thick bonding layer for structural support. This parameter optimization ensures sufficient bonding strength while minimizing the thermal resistance introduced by the bonding layer, thereby maintaining high heat dissipation efficiency
3Temperature
If copper is used as the main material of the drain electrode for high thermal conductivity, then the heat dissipation is improved, but the oxidation resistance is reduced
Solution Approach 1:
The drain electrode is constructed as a composite structure with a copper-based material (high thermal conductivity) as the core and a protective layer (high oxidation resistance) as the outer shell. This composite structure combines the advantages of both materials: the copper core provides excellent thermal conduction for heat dissipation, while the protective outer layer prevents oxidation of the copper, thereby simultaneously achieving high heat dissipation efficiency and oxidation resistance
Solution Approach 2:
A protective layer is introduced as an intermediary between the copper drain electrode material and the external environment. This protective layer acts as a barrier that prevents direct contact between oxygen and the copper surface, thereby preventing oxidation while allowing thermal conduction to proceed through the layer, thus resolving the contradiction between thermal conductivity and oxidation resistance
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
This design enhances heat dissipation efficiency and improves the reliability of the semiconductor device by balancing heat dissipation and bonding strength, reducing thermal resistance and ensuring stable operation.
Implementation Method 1
The drain electrode is also one of heat dissipation paths of the semiconductor device
Data Source
AI summary
A semiconductor device includes a substrate, a first electrode and a second electrode. The semiconductor device includes a MOSFET that has the first electrode as a drain electrode and the second electrode as a source electrode. The first electrode has a layer region provided on a first main surface and a first region extending from the first main surface into the substrate in a first direction from the first electrode to the second electrode. A lower surface of the first electrode protrudes in a direction opposite to the first direction.