Original Field Plate to Decrease the Maximum Electric Field Peak for High-Voltage Diamond Schottky Diode

At a Glance

Metadata	Details
Publication Date	2015-07-30
Journal	IEEE Transactions on Electron Devices
Authors	Houssam Arbess, Karine Isoird, Saleem Hamady, M. Zerarka, Dominique Planson
Institutions	Laboratoire d’Analyse et d’Architecture des Systèmes, Centre National de la Recherche Scientifique
Citations	13
Analysis	Full AI Review Included

Technical Analysis: High-Voltage Diamond Schottky Diode Field Plate Optimization

Document Reference: Original Field Plate to Decrease the Maximum Electric Field Peak for High-Voltage Diamond Schottky Diode (Arbess et al., 2015) Prepared for: 6CCVD Engineering and Sales Teams

Executive Summary

The analyzed research confirms the critical role of MPCVD diamond in future high-power electronics, focusing on optimizing junction termination structures to maximize performance in Schottky diodes.

Core Achievement: Simulation and optimization of novel field plate architectures, resulting in a substantial increase in the simulated Breakdown Voltage (BV) from 1632 V to 2141 V at 700 K.
Electric Field Management: The maximum electric field peak (E_max), a critical failure point due to dielectric breakdown, was reduced significantly from 57 MV/cm to a minimum of 22.7 MV/cm.
Material Necessity: Success hinges on using high-quality diamond (implied Single Crystal Diamond, SCD) with precise doping control (P+ heavy substrate, P- active layer).
Architectural Innovation: Optimization involved complex micro-structuring of the dielectric/diamond interface, including “Pillars,” “Graduated,” and “Mixed” oxide forms, requiring advanced etching (RIE) and custom metalization/dielectric layering.
Dielectric Performance: Changing the dielectric material from silicon oxide (SiO₂) to aluminum oxide (Al₂O₃) was instrumental in achieving the lowest E_max (27 MV/cm for graduated form), emphasizing the need for robust material integration.
6CCVD Value Proposition: The reported P+ and P- layer requirements, custom thicknesses, and specialized termination geometry processing align perfectly with 6CCVD’s core MPCVD diamond material growth and precision engineering services.

Technical Specifications

The following table extracts the hard data points related to material composition, dimensions, and electrical performance of the optimized diamond Schottky diode structures described in the paper.

Parameter	Value	Unit	Context
Material Base	Diamond (Pseudo Vertical)	N/A	High-Voltage Schottky Diode
P+ Substrate Doping	3 x 10²⁰	cm^-3	Heavily Boron Doped, Ohmic Contact Layer
P- Active Layer Doping	8.10¹⁵	cm^-3	Drift Region, determines 1D BV
P- Active Layer Thickness	7	µm	Target thickness for drift region optimization
Operating/Simulation Temperature	700	K	Baseline temperature for results
Ideal 1D Breakdown Voltage	2288	V	Theoretical limit without termination effects
Optimized BV (New Architecture)	2141	V	Achieved with optimized 51 µm field plate length, 1 µm dielectric thickness
Initial BV (Classic Field Plate)	1638	V	Benchmark structure used for comparison
Max E-Field (Initial Architecture)	57	MV/cm	E-field peak at field plate edge
Min E-Field (Optimized Mixed Form)	22.7	MV/cm	Achieved using Mixed form architecture and Al₂O₃
Standard Dielectric E_crit (SiO₂)	10	MV/cm	Critical field of silicon oxide, lower than diamond
Optimized Field Plate Length (L_FP)	51	µm	Geometrical parameter for 2141 V structure
Optimized Dielectric Thickness (T_Diel)	1	µm	Geometrical parameter for 2141 V structure

Key Methodologies

The study relied primarily on numerical simulation (TCAD) coupled with advanced micro-structuring concepts to manage electric field distribution at the critical junction termination.

Simulation Platform: Sentaurus TCAD (Technology Computer Aided Design) software was utilized, incorporating the Van Overstraeten’s model for breakdown voltage calculation.
Device Structure (Initial): A pseudo vertical Schottky diode consisting of a heavily P-doped diamond substrate (P+, 3x10²⁰ cm^-3) overlaid with a 7 µm lightly P-doped epitaxial layer (P-, 8.10¹⁵ cm^-3).
Junction Termination Baseline: Initial optimization used a conventional field plate termination architecture with SiO₂ dielectric to achieve a 1638 V breakdown voltage.
New Field Plate Architecture: Introduced a modified field plate design where the diamond below the field plate was replaced with an optimized thickness of dielectric material to eliminate stress corners in the electrode path.
Advanced Termination Architectures (E-Field Peak Reduction): To reduce the electric field peak at the dielectric/diamond interface, three innovative geometries were simulated, designed to increase the number of corners along the potential lines:
1. Pillars Dielectric Form: Oxide structured into a series of pillars (width 2 µm, varying height).
2. Graduated Dielectric Form: Multi-step oxide structure (three steps assumed for technological feasibility).
3. Mixed Dielectric Form: Combination of the above methods.
Material Selection Change: Testing high-k dielectrics, specifically comparing Silicon Oxide (SiO₂) against Aluminum Oxide (Al₂O₃), showed that Al₂O₃ delivered superior E-field peak suppression in the termination structures.
Required Fabrication Steps (Implied): Achieving these geometries requires precision steps including Diamond Reactive Ion Etching (RIE), precision thin-film dielectric deposition, and wet/dry etching for metal contact definition.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the foundational MPCVD diamond materials and engineering services required to replicate, validate, and advance the high-voltage diode research presented in this paper.

Applicable Materials

To replicate the high-performance structure (P+/P- pseudo vertical diode), researchers require highly controlled, high-purity single crystal diamond (SCD) layers grown via MPCVD.

Required Layer	Material Recommendation	6CCVD Capability Match
P- Drift Layer	Optical Grade SCD (Low defect density)	SCD plates/wafers with high purity, required for maximizing mobility and breakdown strength.
P+ Substrate	Heavy Boron-Doped Diamond (BDD)	Boron-Doped (BDD) SCD or PCD materials capable of achieving target doping levels of 3 x 10²⁰ cm^-3 for low resistance ohmic contacts.
Custom Thickness	Epitaxial Layer Growth (7 µm)	6CCVD offers custom SCD thickness control, precisely matching the 7 µm requirement (range 0.1 µm to 500 µm).

Customization Potential

The success of the proposed device relies heavily on the integration of precise dimensions and specialized contacts, areas where 6CCVD provides critical in-house engineering support.

Precision Dimensioning: The study specifies critical lengths such as the 7 µm active layer and the 51 µm field plate overlap. 6CCVD offers custom thickness control for SCD up to 500 µm and precision laser cutting services to achieve the complex geometries required for Pillars, Graduated, or Mixed field plates.
Advanced Metalization: The device fabrication requires both ohmic contacts (P+) and Schottky contacts (anode). 6CCVD offers extensive in-house metalization capabilities, including, but not limited to: Ti, Pt, Au, Pd, W, and Cu. This is vital for researchers designing the Schottky contact or the field plate electrode itself.
Surface Finish: Maintaining the efficiency of the diode requires superior surface quality. 6CCVD guarantees ultra-smooth polishing down to Ra < 1nm for SCD materials, ensuring optimal contact interface and dielectric deposition quality, minimizing scatter and premature breakdown points.

Engineering Support

The challenges detailed in this paper—managing E-field peaks at dielectric interfaces, optimizing doping concentrations, and achieving precise dimensional control—are complex material science issues.

6CCVD’s in-house PhD-level team specializes in Diamond Power Electronics and High-Temperature Devices. We provide material consultation to assist researchers in selecting the optimal epitaxial growth recipe (SCD vs. BDD) and processing parameters necessary for high-voltage applications, ensuring materials meet the stringent requirements needed to replicate or extend this research into functional high-power diamond devices.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

Tech Support

Original Source

DOI: https://doi.org/10.1109/ted.2015.2456073

References

2008 - Impact of high-k dielectrics on breakdown performances of SiC and diamond Schottky diodes [Crossref]