SOI MOSFET Structure With Heat Conduction Column for Self-Heating
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Solution Overview
Problem
The silicon-on-insulator metal-oxide-semiconductor field-effect transistor (SOI MOSFET) experiences significant self-heating due to poor heat conductivity of the SiO2 buried oxide layer, leading to increased lattice temperature and reduced drain current performance.
Innovation Solution
Incorporation of a heat conduction column made of high heat conductivity materials like SiC, GaN, or InN that penetrates through the buried oxide layer, allowing heat to be dissipated directly from the active zone to the substrate, and an inclined gate structure with a notch to reduce heat production and electric field peaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a SiO2 buried oxide layer is used for isolation, then device isolation and electrical performance are improved, but heat dissipation capability deteriorates due to low thermal conductivity
Solution Approach 1:
The patent uses a composite structure combining SiO2 buried oxide layer with high thermal conductivity materials (SiC, GaN, or diamond) arranged in an interlaced or alternating pattern. This composite approach allows the SiO2 to provide electrical isolation while the high thermal conductivity materials create heat dissipation channels, resolving the contradiction between isolation performance and heat dissipation capability.
Solution Approach 2:
The buried oxide layer is segmented into regions with different thermal conductivity characteristics. Rather than using a uniform SiO2 layer, the patent divides the isolation structure into multiple segments including high thermal conductivity material regions and low thermal conductivity SiO2 regions, allowing differential functionality within the same isolation layer.
2Productivity
If the device size is reduced for miniaturization, then integration density is improved, but self-heating effect worsens due to reduced heat dissipation area
Solution Approach 1:
The patent addresses the self-heating problem by introducing vertical heat dissipation channels through the use of high thermal conductivity materials that extend through the device structure. This vertical dimension of heat dissipation compensates for the reduced lateral heat dissipation area caused by device miniaturization, allowing high integration density without excessive self-heating.
3Speed
If high electric field is applied to increase electron drift velocity, then current performance is improved, but heat generation worsens due to increased electron-lattice collision
Solution Approach 1:
The high thermal conductivity materials (SiC, GaN, diamond) act as intermediary heat transfer paths between the active zone where electron-lattice collisions occur and the substrate. These intermediary materials provide efficient heat transfer channels that quickly conduct away the heat generated by electron drift, preventing heat accumulation while maintaining high electron velocities.
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 solution effectively reduces the lattice temperature of the active zone, preventing drain current decrease and enhancing the breakdown voltage, with a 16.2% decrease in maximum temperature and increased current and breakdown voltage performance.
Implementation Method 1
the heat conduction column penetrates through the buried oxide layer; a top wall of the heat conduction column is in contact with the active zone, and a bottom wall of the heat conduction column extends into the substrate layer
Data Source
AI summary
A silicon-on-insulator metal-oxide-semiconductor field-effect transistor (SOI MOSFET) structure is provided, including a substrate layer; a buried oxide layer which is arranged on an upper surface of the substrate layer and is made of SiO2; an active zone which is arranged on an upper surface of the buried oxide layer; a source electrode and a drain electrode which are arranged on an upper surface of the active zone; a gate dielectric layer which is arranged between the source electrode and the drain electrode; a gate electrode which is provided in the gate dielectric layer; and a heat conduction column which penetrates through the buried oxide layer, and its top wall is in contact with the active zone. The heat conduction column dissipates heat in the active zone, resulting in a lattice temperature of the active zone will not increase extremely and avoiding a decrease of a current of the drain electrode.