Diamond Semiconductor Mesa Structure for Dielectric Breakdown Voltage
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Solution Overview
Problem
Diamond semiconductor devices face challenges in achieving high dielectric breakdown voltage due to difficulties in impurity doping and plane orientation dependency, which limits their practical application in power devices.
Innovation Solution
A semiconductor device structure featuring a mesa structure with a specific orientation and an n-type diamond semiconductor region with controlled impurity concentration, combined with epitaxial growth methods, is used to enhance dielectric breakdown voltage. This structure includes a p+-type diamond semiconductor layer, an i-type or p-type diamond semiconductor layer, and an n+-type diamond semiconductor layer, with an n-type diamond semiconductor region on the side surface for electric field relaxation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional impurity doping methods are used in diamond semiconductor devices, then device fabrication is attempted, but the doping process is difficult and impurity concentration control is poor
Solution Approach 1:
The patent changes the fundamental parameter of impurity introduction from post-growth doping to in-growth doping during epitaxial process. By controlling doping conditions (dopant type, concentration, temperature, pressure) during the epitaxial growth stage, the patent achieves precise impurity concentration control while avoiding the difficulties of conventional doping methods. This parameter change transforms an intractable doping problem into a controllable growth process.
2Reliability
If diamond semiconductor devices are manufactured without considering plane orientation, then fabrication is simplified, but dielectric breakdown voltage is insufficient
Solution Approach 1:
The patent applies local quality by introducing n-type diamond semiconductor regions with different impurity concentrations at specific locations (side surfaces of mesa structure) rather than uniform doping throughout. This localized doping approach targets specific areas where electric field relaxation is needed, improving dielectric breakdown voltage without requiring complex overall structural changes. The different regions serve different functions: high impurity concentration at contacts for low resistance, low impurity concentration in bulk for high breakdown voltage.
Solution Approach 2:
The patent moves from conventional planar device structure to three-dimensional mesa structure with controlled side surface orientation. By specifying that side surfaces have orientations of (110), (100), or (111) planes, the patent exploits the anisotropic properties of diamond crystal structure in different dimensions. This dimensional approach allows electric field relaxation to occur preferentially in specific crystallographic directions, enhancing dielectric breakdown voltage through geometric configuration rather than material composition changes alone.
3Reliability
If electric field stress is not managed, then device structure is simpler, but dielectric breakdown voltage is limited
Solution Approach 1:
The patent introduces n-type diamond semiconductor regions as intermediary structures between the high-field region (p-n junction) and the bulk diamond substrate. These intermediary regions with controlled impurity concentrations act as transition zones that gradually relax the electric field stress, preventing abrupt field concentration at interfaces. The intermediary regions serve as buffer zones that mediate the electric field distribution, allowing higher overall breakdown voltage without requiring complete redesign of the device architecture.
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 proposed structure effectively improves the dielectric breakdown voltage of diamond semiconductor devices, enabling their practical application in power devices by reducing electric field stress and stabilizing impurity concentration through controlled growth orientations and doping efficiency.
Implementation Method 1
an n-type first diamond semiconductor region provided on the side surface, the first diamond semiconductor region being in contact with the second diamond semiconductor layer and having an n-type impurity concentration lower than an n-type impurity concentration of the second diamond semiconductor layer
Implementation Method 2
combined with epitaxial growth methods, is used to enhance dielectric breakdown voltage
Data Source
AI summary
A semiconductor device according to an embodiment includes an i-type or a p-type first diamond semiconductor layer, an n-type second diamond semiconductor layer provided on the first diamond semiconductor layer, a mesa structure and an n-type first diamond semiconductor region provided on the side surface. The mesa structure includes the first diamond semiconductor layer, the second diamond semiconductor layer, a top surface with a plane orientation of ±10 degrees or less from a {100} plane, and a side surface inclined by 20 to 90 degrees with respect to a direction of <011>±20 degrees from the {100} plane. The first diamond semiconductor region is in contact with the second diamond semiconductor layer and has an n-type impurity concentration lower than an n-type impurity concentration of the second diamond semiconductor layer.