MOS Transistor Trench Electrodes Thermal Dissipation
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Solution Overview
Problem
Thick interlayer oxides in semiconductor devices impede heat transfer from active portions to thermal sinks due to their low thermal conductivity, limiting the effectiveness of heat dissipation during high-temperature conditions such as short-circuit events.
Innovation Solution
The method involves creating multiple separated gate electrodes within trenches in a semiconductor body, with each electrode being thermally and electrically connected to a metallization layer through strategically formed openings in isolation layers, enhancing heat transfer by increasing the contact area between the electrodes and the metallization layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thick interlayer oxides are used to electrically isolate metal layers from the semiconductor body, then electrical isolation is improved, but heat transfer is impeded due to low thermal conductivity
Solution Approach 1:
The patent divides the originally single continuous metal layer into multiple separated metal regions. Each separated metal region is independently connected to the semiconductor body through its own contact opening, thereby creating multiple parallel heat transfer pathways that bypass the thermal bottleneck of the thick interlayer oxide.
Solution Approach 2:
The patent transitions from a planar heat transfer path (through the thick oxide layer) to a three-dimensional structure where heat can transfer vertically through contact openings to the semiconductor body, then laterally through the semiconductor, and finally to the metal layers. This dimensional change creates alternative heat transfer routes that avoid the thermal resistance of the oxide layer.
2Temperature
If thick metallization layers are applied at the top and bottom surfaces to spread heat, then heat distribution is improved, but heat transfer from the silicon surface is impeded by thick interlayer oxides
Solution Approach 1:
The patent introduces the semiconductor body as an intermediary heat transfer medium. Heat flows from the active portions through the semiconductor body to the separated metal regions, using the semiconductor material (which has higher thermal conductivity than the oxide) as a thermal bridge to overcome the bottleneck created by the thick interlayer oxide.
3Temperature
If multiple separated gate electrodes are created within trenches with strategic openings in isolation layers, then heat transfer surface area is increased, but device complexity increases
Solution Approach 1:
The patent designs the separated metal regions to serve dual functions: they act as gate electrodes for device operation and simultaneously function as heat sinks for thermal management. This multi-functionality increases heat transfer surface area without requiring entirely separate thermal management structures, thereby limiting the increase in overall 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
This configuration improves thermal resistance by increasing the surface area for heat transfer from the semiconductor body to the metallization layer, effectively managing high temperatures and preventing device failure during short-circuit conditions.
Implementation Method 1
The high thermal conductivity spreads the heat across the whole semiconductor chip surface and thus enables a proper cooling of the device
Data Source
AI summary
A MOS transistor is produced by forming a first trench in a semiconductor body, forming a first isolation layer on inner surfaces of the first trench, and filling the first trench with conductive material to form a first electrode within the first trench. A portion of the first electrode is removed along one side wall of the first trench to form a cavity located within the first trench. A second isolation layer is formed on inner surfaces of the cavity, and the cavity is at least partially filled with conductive material to form a second electrode within the cavity. A structured third isolation layer is formed on a top surface of the semiconductor body, and a metallization layer is formed on the structured third isolation layer. The first or the second electrode is electrically and thermally connected to the metallization layer via openings in the structured third isolation layer.