Structure oriented compact model for advanced trench IGBTs without fitting parameters for extreme condition: Part I

doi:10.1016/j.microrel.2011.07.050

Microelectronics Reliability

Volume 51, Issues 9–11, September–November 2011, Pages 1933-1937

https://doi.org/10.1016/j.microrel.2011.07.050 Get rights and content

Abstract

A device structure based compact model for advanced trench gate IGBTs is proposed. The model is formulated only with device structure parameters so that no fitting parameters are required. The model is applicable to extreme conditions such as under very low or high temperatures. The validity of the model formulation is confirmed with two-dimensional TCAD simulation for voltage range of 1.2 kV and 3.3 kV IGBTs, and for temperature range of 300 K and 450 K. In this paper conduction mode formulation is proposed which has the potential to be used for system level failure analysis.

Introduction

IGBT compact models, such as Hefner model [1], have been widely used in power electronics system and circuit design as the device has expanded the application from small appliances to EV/HEV and tractions, etc. [2], [3]. The compact models enable to simulate large scale IGBT inverters and systems for many cycle of switching, where TCAD simulation cannot cover.

Most of the IGBT compact models have been formulated based on the combination of physics based simplified analytical equations, equivalent circuits and behavior models with a number of fitting parameters. As far as the models are used within the predetermined validity confirmed operation range of the models, the circuit simulators effectively show the sufficiently accurate results. Once the condition exceeds the validity confirmed range, such as high temperature condition, the model requires re-fitting of the parameters so as to extend the validity range.

A novel formulation of IGBT compact model proposed in this paper eliminates the fitting parameters from the model equations and only uses the device structure parameters as the model parameters. This concept enables the new model to be used in extreme condition such as very low or high temperature and expands the compact model function from circuit optimization to circuit–device coupled optimization since the model can applicable for wide range of device structure thanks to eliminating fitting parameters. In result, for example, the model can be also applied to analyze current imbalance in a chip due to the lack of process uniformities.

The proposed model is designed to cover the advanced IGBT structures with the injection-enhancement structure with trench gate structure on the Cathode side [4] and low injection structure on the Anode side [5], which are called the thin wafer IGBTs or the field stop (FS) IGBTs with the improved tradeoff between on-state voltage drop and turn-off loss.

In this paper, we show the modeling approach and verification results. We compare calculation results between the model and two-dimensional TCAD simulation. The result shows that the model can represent latest improvement of IGBTs accurately. It would be able to apply for system level failure analysis with complicated control sequences and severe temperature condition.

Section snippets

N-base carrier distribution

Fig. 1 shows cross-sectional view of Trench gate IGBT. N-base carrier concentration n(x) can be formulated with carrier lifetime τ and diffusion length L_A of high injection condition [6]. $L_{A}^{2} \frac{d^{2} n (x)}{{dx}^{2}} = n (x) + τ \frac{dn (x)}{dt}$

For the steady state conditions, time dependent term is omitted and the solution can be formed as $n (x) = L_{A} \frac{- \frac{dn}{dx} (x_{1}) \cdot \cosh (\frac{x_{2} - x}{L_{A}}) + \frac{dn}{dx} (x_{2}) \cdot \cosh (\frac{x - x_{1}}{L_{A}})}{\sinh (\frac{x_{2} - x_{1}}{L_{A}})}$ where x₁ and x₂ are positions of Anode edge and Cathode edge of N-base region as shown in Fig. 1. Eq. (2) means that N-base carrier

Model validation for variety of structure and temperature

The established model was verified by comparing with two-dimensional TCAD calculation results. We used two types of IGBTs; 1.2 kV thin wafer PT-IGBT and 3.3 kV IEGT for model validation. Table 1 shows physical constants used for the calculations by the established model and TCAD. Temperature dependence is considered for all three constants [8], [9]. Doping concentration dependence is also considered for carrier mobility and lifetime [10], [11]. Electron mobility degradation by normal electric

Conclusion

We proposed new compact model for Trench gate IGBT. The model is formulated by only physical parameters. The bipolar equation is formulated with injection efficiencies of Anode and Cathode side. Anode injection efficiency is formulated by doping concentration and junction depth of P-emitter and N-buffer. Cathode injection efficiency is formulated with trench gate structure dimensions and carrier mobility. Modeling should be easier because fitting parameters do not need to be adjusted. The model

References (11)

M.S. Tyagi et al.
Minority carrier recombination in heavily-doped silicon
Solid-State Electron
(1983)
Hefner AR. Analytical modeling of device-circuit interactions for the power insulated gate bipolar transistor (IGBT)....
M. Cotorogea
Physics-based SPICE-model for IGBTs with transparent emitter
IEEE Trans Power Electron
(2009)
L. Lu et al.
Modeling of MOS-side carrier injection in trench-gate IGBTs
IEEE Trans Ind Appl
(2010)
M. Kitagawa et al.
A 4500 V injection enhanced insulated gate bipolar transistor (IEGT) operating in a mode similar to a thyristor
IEDM Tech Dig
(1993)

There are more references available in the full text version of this article.

Cited by (14)

Bias voltage criteria of gate shielding effect for protecting IGBTs from shoot-through phenomena
2018, Microelectronics Reliability
Citation Excerpt :
IGBTs are widely applied in various power electronics systems, such as electric vehicles, railways and for high-voltage direct current (HVDC) transition, and the market is rapidly expanding. Since 2011, a new generation IGBT based on a scaling principle has been proposed and fabricated experimentally [1–4]. The IGBT features a low collector-emitter saturation voltage (VCE(sat)) and low gate voltage driving.
In this paper, we propose the criteria of bias voltage from parasitic capacitance and demonstrate the criteria in an experiment with the present IGBT. The bias voltage criteria are theoretically predicted for the new generation IGBT based on the scaling principle. For safe switching, the required gate voltage bias is predicted to be −1.2 V or less for the present IGBTs and − 6 V or less is required to completely cancel the gate noise voltage. From the IGBT design, the bias voltage of scaling IGBT requires −2 V to completely cancel the gate noise voltage.
Structure oriented compact model for advanced trench IGBTs without fitting parameters for extreme condition: Part II
2014, Microelectronics Reliability
Citation Excerpt :
The improvement has been achieved by optimizing device cell pattern, introducing trench gate structures, and optimizing vertical IGBT structure. We already proposed analytical model for the on-state of the advanced IGBT in previous research [1–3]. The compact model eliminates the fitting parameters in the model equations and only uses the device structure parameters.
Compact model for expressing turn-off waveform for advanced trench gate IGBTs is proposed even under high current density condition. The model is analytically formulated only with device structure parameters so that no fitting parameters are required. The validity of the model is confirmed with TCAD simulation for 1.2–6.5 kV class IGBTs. The proposed turn-off model is sufficiently accurate to calculate trade-off curve between turn-off loss and saturation collector voltage under extremely high current conduction, so that the model can be used for system design with the advanced trench gate IGBTs.
IGBT scaling principle toward CMOS compatible wafer processes
2013, Solid-State Electronics
Citation Excerpt :
The results show that the IGBT even with shallower Cathode structure which designed by the proposed scaling principle has lower on-state voltage drop than the conventional structure. After that, we discuss about this improvement by referring our previously proposed “Structure Oriented” analytical model [19]. The improvement can be theoretically explained by the compact model formation.
A scaling principle for trench gate IGBT is proposed. CMOS technology on large diameter wafer enables to produce various digital circuits with higher performance and lower cost. The transistor cell structure becomes laterally smaller and smaller and vertically shallower and shallower. In contrast, latest IGBTs have rather deeper trench structure to obtain lower on-state voltage drop and turn-off loss. In the aspect of the process uniformity and wafer warpage, manufacturing such structure in the CMOS factory is difficult. In this paper, we show the scaling principle toward shallower structure and better performance. The principle is theoretically explained by our previously proposed “Structure Oriented” analytical model. The principle represents a possibility of technology direction and roadmap for future IGBT for improving the device performance consistent with lower cost and high volume productivity with CMOS compatible large diameter wafer technologies.
Bipolar Transistor Test Structures for Extracting Minority Carrier Lifetime in IGBTs
2020, IEEE Transactions on Semiconductor Manufacturing
Self-Turn-on-Free 5V Gate Driving for 1200V Scaled IGBT
2019, Proceedings of the International Symposium on Power Semiconductor Devices and ICs
Demonstration of 1200V Scaled IGBTs Driven by 5V Gate Voltage with Superiorly Low Switching Loss
2018, Technical Digest - International Electron Devices Meeting, IEDM

View all citing articles on Scopus

View full text

Structure oriented compact model for advanced trench IGBTs without fitting parameters for extreme condition: Part I

Abstract

Introduction

Section snippets

N-base carrier distribution

Model validation for variety of structure and temperature

Conclusion

Solid-State Electron

Physics-based SPICE-model for IGBTs with transparent emitter

IEEE Trans Power Electron

Modeling of MOS-side carrier injection in trench-gate IGBTs

IEEE Trans Ind Appl

A 4500 V injection enhanced insulated gate bipolar transistor (IEGT) operating in a mode similar to a thyristor

IEDM Tech Dig