L. Coulbeck

Numerical Parameterization of Chemical-Vapor-Deposited (CVD) Single-Crystal Diamond for Device Simulation and Analysis

High-quality electronic-grade intrinsic chemical- vapor-deposited (CVD) single-crystal diamond layers having exceptionally high carrier mobilities have been reported by Isberg et al. This makes the realization of novel electronic devices in diamond, particularly for high-voltage and high-temperature applications, a viable proposition. As such, material models which can capture the particular features of diamond as a semiconductor are required to analyze, optimize, and quantitatively design new devices. For example, the incomplete ionization of boron in diamond and the transition to metallic conduction in heavily boron-doped layers require accurate carrier freeze-out models to be included in the simulation of diamond devices. Models describing these phenomena are proposed in this paper and include numerical approximation of intrinsic diamond which is necessary to formulate doping- and temperature-dependent mobility models. They enable a concise numerical description of single-crystal diamond which agrees with data obtained from material characterization. The models are verified by application to new Schottky m-i-p+ diode structures in diamond. Simulated forward characteristics show excellent correlation with experimental measurements. In spite of the lack of impact ionization data for single-crystal diamond, approximation of avalanche coefficient parameters from other wide-bandgap semiconductors has also enabled the reverse blocking characteristics of diamond diodes to be simulated. Acceptable agreement with breakdown voltage from experimental devices made with presently available single-crystal CVD diamond is obtained.

Comparison of Trench Gate IGBT and CIGBT Devices for Increasing the Power Density From High Power Modules

Recently much research has been focused on increasing the functionality and output power density per unit area in power electronic modules without increasing board space. In high power applications, MOS-controlled devices with trench gates are the most desirable as their reduced V ce(sat) enables increased conduction current density. However, with increased drift region thickness, there is significant increase in conduction loss in trench gate-insulated gate bipolar transistor (T-IGBT) due to low plasma density from inherent p-n-p transistor action. In comparison, a well-designed MOS-controlled thyristor structure such as the trench-clustered insulated gate bipolar transistor (T-CIGBT), can provide low on-state conduction loss with gate voltage turn-on and turn-off. The comparison of 3.3 kV/800 A simulation results presented in this paper shows that the T-CIGBT is a superior candidate over TIGBT to increase the power density from existing high-voltage IGBT module footprints.

Ultra-high voltage device termination using the 3D RESURF (super-junction) concept - experimental demonstration at 6.5 kV

We propose here and experimentally demonstrate a novel breakdown termination termed The 3D-RESURF Termination that can be applied to a large class of high to ultra-high voltage devices, such as diodes, thyristors, IGBTs, etc. The novel termination is based on the 3D RESURF concept (lateral super-junction) proposed by us and others for lateral integrable devices. We have fabricated vertical diodes and IGBTs rated at 6.5 kV and demonstrated that the use of 3D RESURF p and n layers placed between adjacent p+ floating rings resulted in maximum breakdown voltage (6.5 kV). This is 2.5 kV larger than the breakdown voltage obtained from a standard field ring terminated device fabricated side by side on the same chip. Moreover, the 3D-RESURF edge termination uses a total length of 1 mm, which is only 60% of standard 6.5 kV JTE terminations. This results in area saving of up to 40%, depending on the active area of the chip.

High power density IGBT module for high reliability applications

The blocking voltage rating of an IGBT module have reached up to 6.5kV, however for true high power application such as traction drives, the current rating has to increase as well. This is mainly achieved by either improving the packing density of semiconductor chips per given module footprint and or improving the current density of the semiconductor chips used in the IGBT module. In this paper we explore how the current ratings of an 800A, 3.3KV module with 140 × 130mm footprint can be improved for a fixed base-line reliability.

On-state analytical modeling of IGBTs with local lifetime control

A two-dimensional on-state analytical model of the insulated gate bipolar transistor (IGBT) with local lifetime control is developed. The model accounts for the effect of local lifetime killing in particular the effective value of the lifetime and the position of the local lifetime control region on the excess carrier distribution in the IGBT during its on-state operation. It is shown that the local lifetime killing in the vicinity of the anode junction causes a reduction in the anode injection efficiency leading to improved on-state/turn-off behavior. The accuracy of the analytical model is verified through numerical simulations carried out using the MEDICI device simulator.

Analysis of lifetime control in high-voltage IGBTs

Abstract This paper discusses the effectiveness of the lifetime control technology in high-voltage insulated gate bipolar transistors (IGBTs) by using both numerical simulations and a two-dimensional on-state analytical model specifically developed for IGBTs with local lifetime killing. A comprehensive study of the static and dynamic performance of IGBTs using lifetime control technology in comparison with IGBTs featuring reduced anode injection efficiency structures is made. We show for the first time that IGBTs with low anode injection efficiency have similar or better on-state/switching trade-off when compared to equivalent IGBTs using lifetime control technology. We also show that both the local lifetime control and the low anode injection efficiency techniques are superior to full irradiation. The low anode injection efficiency is particularly better than the local lifetime control technique when applied to punch-though IGBTs while no difference between the two is found in non-punch-though IGBTs.

Design and optimisation of suitable edge terminations for 6.5 kV IGBTs

This paper is addressed to the design and optimisation of junction termination extension and floating guard rings edge termination structures to integrate 6.5 kV IGBT devices. The developed edge termination structures are extensively analysed through numerical simulations, and experimental data on fabricated diode structures are correlated with simulation results.

Numerical and Experimental Analysis of Single Crystal Diamond Schottky Barrier Diodes

We present our findings on the numerical and experimental analysis of diamond Schottky Barrier diodes (SBDs) comprising of intrinsic single crystal (SC) chemical vapour deposited (CVD) diamond layers grown on highly boron doped substrates also grown by CVD. Good correlation with experimental results has been achieved through numerical modelling that has incorporated previously reported data on transport physics and carrier activation. With our numerical model, we are able to match to within 12 to 15% of the measured forward characteristics of fabricated diamond SBDs up to 2 V in excess of the turn on voltage, for two different Schottky metals.

Accurate conduction and switching loss models of IGBTs for resonant converter design

This paper presents an accurate switching and conduction loss model for zero current switching (ZCS) and zero voltage switching (ZVS) IGBTs. Mathematical modelling is carried out giving careful consideration to all the significant features and dependant parameters, namely collector current, resonant frequency and case temperature. Model parameter extraction is carried out using the experimental results from two test circuits. The model shows excellent agreement with the experimental results and SPICE simulation results obtained using a physical IGBT model.

Design considerations for 6.5 kV IGBT devices

Abstract This article addresses the design of an optimal cell suitable for 6.5 kV Insulated Gate Bipolar Transistor (IGBTs). Simulations of the layout optimisation and process technology considerations for the 6.5 kV IGBT basic cell are presented. The simulation led directly to a monitor chip with several variant IGBT test structures, which has been fabricated and characterised. As a result, a large area 6.5 kV IGBT and FRD has been designed, fabricated and characterised as a 200 A power module with V cesat =4 V at 25 °C and switching from 4.4 kV at 125 °C, exhibiting excellent electrical performance.