MOSFET Thermal Boost Materials for High-Temperature Mobility
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Solution Overview
Problem
Semiconductor transistors experience performance degradation at high operating temperatures due to reduced carrier mobility, which is challenging to address in existing technologies, particularly for applications requiring high performance across a wide temperature range such as in oil rigs, servers, military, and space exploration.
Innovation Solution
Incorporating thermal boost materials with specific coefficients of thermal expansion (CTE) adjacent to transistors, such as high positive linear CTE materials for p-type MOSFETs and negative linear CTE materials for n-type MOSFETs, to induce strain in the channel region as temperature increases, thereby enhancing carrier mobility and compensating for temperature-induced mobility degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If transistors operate at high temperatures, then power and processing capability are improved, but carrier mobility degrades causing performance loss
Solution Approach 1:
The patent changes the physical state of the channel region by inducing mechanical strain through thermal expansion/contraction of adjacent materials. By selecting materials with specific CTE values, the channel region experiences tensile or compressive strain that modifies carrier mobility parameters, allowing high-temperature operation while maintaining performance
Solution Approach 2:
The patent directly utilizes thermal expansion/contraction of materials adjacent to the transistor channel. Materials with positive CTE expand at high temperatures to induce compressive strain, while materials with negative CTE contract to induce tensile strain. This thermal-mechanical coupling transforms temperature changes from harmful to beneficial, improving carrier mobility precisely when temperature increases
2Reliability
If thermal boost materials are added adjacent to transistors, then carrier mobility is improved at high temperatures, but device structure complexity increases
Solution Approach 1:
The patent merges the thermal management function with the performance enhancement function by using the same adjacent materials for both purposes. The thermal boost materials are integrated into the existing transistor structure without requiring separate cooling systems or additional control mechanisms, thus improving carrier mobility while minimizing added complexity
Solution Approach 2:
The patent introduces thermal boost materials as intermediary elements between the transistor channel and the external environment. These materials mediate the thermal effects by converting temperature changes into mechanical strain that benefits carrier mobility, acting as a buffer that transforms environmental conditions into performance improvements
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 use of thermal boost materials improves transistor and circuit performance at high temperatures by increasing carrier mobility and maintaining performance across a wide temperature range, critical for applications like oil rigs, servers, military, and space exploration.
Implementation Method 1
the material may derive its thermal enhancement properties as an integrated circuit's operating temperature increases. Such expansion or contraction tends to cause strain on the channel region
Implementation Method 2
In the case of n-type MOSFET (NMOS) devices, thermal boost materials with a negative linear CTE, such as less than 0 ppm/°C at around 20 °C, may be used to induce tensile strain
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 1E~1F
AI summary
Techniques are disclosed for forming a transistor with enhanced thermal performance. The enhanced thermal performance can be derived from the inclusion of thermal boost material adjacent to the transistor, where the material can be selected based on the transistor type being formed. In the case of PMOS devices, the adjacent thermal boost material may have a high positive linear coefficient of thermal expansion (CTE) (e.g., greater than 5 ppm/ C at around 20 C) and thus expand as operating temperatures increase, thereby inducing compressive strain on the channel region of an adjacent transistor and increasing carrier (e.g., hole) mobility. In the case of NMOS devices, the adjacent thermal boost material may have a negative linear CTE (e.g., less than 0 ppm/ C at around 20 C) and thus contract as operating temperatures increase, thereby inducing tensile strain on the channel region of an adjacent transistor and increasing carrier (e.g., electron) mobility.