Epitaxial Substrate Gradient Doping Heat Dissipation
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Solution Overview
Problem
Conventional semiconductor substrates face challenges in achieving high breakdown voltage, low leakage current, and efficient heat dissipation, particularly for high-power and high-frequency applications, where existing SOI substrates suffer from low heat dissipation efficiency due to the oxide layer acting as a poor heat conductor.
Innovation Solution
An epitaxial substrate is developed with a deposition layer of homogeneous material having a gradient doping concentration and resistivity, including a high impedance layer region with resistivity greater than 1500 ohm-cm, directly formed on a substrate, which reduces leakage current and enhances heat dissipation by using a buffer layer and an epitaxial layer primarily made of group III-V nitride.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxide layer is added into two silicon substrates to reduce leakage current, then the leakage current is reduced, but the heat dissipation efficiency deteriorates
Solution Approach 1:
The invention removes the oxide layer from the substrate structure entirely. Instead of using an oxide layer for insulation, the patent employs a semiconductor layer with controlled doping concentration to achieve both electrical insulation and thermal conduction, thereby eliminating the heat dissipation problem caused by the oxide layer while maintaining low leakage current
Solution Approach 2:
The invention changes the electrical parameters of the semiconductor layer by controlling its doping concentration to be lower than that of the substrate, creating a high-impedance region that provides electrical insulation without requiring an oxide layer. This parameter change allows the same material to serve both thermal conduction and electrical insulation functions
2Reliability
If the doping concentration is increased to reduce leakage current, then the leakage current is reduced, but the heat dissipation efficiency deteriorates
Solution Approach 1:
The invention applies different doping concentrations to different regions: the substrate has high doping concentration for mechanical strength and carrier supply, while the semiconductor layer has low doping concentration for electrical insulation. This local differentiation allows each region to optimize its function without compromising the other
Solution Approach 2:
The invention changes the doping concentration parameter from uniform (conventional) to gradient (invention), with the semiconductor layer having lower doping concentration than the substrate. This parameter change creates a high-impedance region that reduces leakage current while maintaining good heat dissipation through the heavily doped substrate
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 epitaxial substrate achieves low leakage current and improved heat dissipation efficiency, making it suitable for high-temperature applications and broader device performance, particularly in RF devices.
Implementation Method 1
the deposition layer includes a gradient resistivity which includes a high impedance layer region having a resistivity at least greater than 1500 ohm-cm
Implementation Method 2
since the deposition layer is directly formed on the substrate, and the deposition layer and the substrate are formed of a homogeneous material, whereby the epitaxial substrate could include a good heat dissipation efficiency
Implementation Method 3
the gradient doping concentration has a minimum value at the first surface
Data Source
AI summary
An epitaxial substrate and a method for forming the same are disclosed. The epitaxial substrate includes a substrate, a deposition layer, a buffer layer and an epitaxial layer. The deposition layer is directly formed on the substrate, wherein the deposition layer includes a gradient doping concentration, and has a first surface and a second surface which are opposite to each other; the gradient doping concentration has a minimum value at the first surface. The buffer layer is formed on the deposition layer, and an epitaxial layer is formed on the buffer layer. The epitaxial layer is mainly formed of group III-V nitride. The substrate and the deposition layer are formed of homogeneous material. Since the deposition layer is directly formed on the substrate, and the deposition layer and the substrate are formed of a homogeneous material, the epitaxial substrate includes a good heat dissipation efficiency and low leakage current.