Breakdown Voltage for Superjunction Power Devices With Charge Imbalance: An Analytical Model Valid for Both Punch Through and Non Punch Through Devices

Abstract

An analytical model for the electric field and the breakdown voltage (BV) of an unbalanced superjunction (SJ) device is presented in this paper. The analytical technique uses a superposition approach treating the asymmetric charge in the pillars as an excess charge component superimposed on a balanced charge component. The proposed double-exponentialmodel is able to accurately predict the electric field and the BV for unbalanced SJ devices in both punch through and non punch through conditions. The model is also reasonably accurate at extremely high levels of charge imbalance when the devices behave similarly to a PiN diode or to a high-conductance layer. The analytical model is compared against numerical simulations of charge unbalanced SJ devices and against experimental results

Optimization of Specific On-Resistance of Balanced Symmetric Superjunction MOSFETs Based on a Better Approximation of Ionization Integral

“…Although (4) and (5) are presented based on the punchthrough (PT) case, i.e., the drift region is fully depleted, they are also effective in calculating the breakdown voltage even for the nonpunchthrough (NPT) case, setting the unphysical negative electric field in the undepleted region to be zero [8]. From (5), the PT condition, i.e., when the electric field at A or B reaches zero [6], can be deduced as 0…”

“…By substituting the electric field line expression (8) into (1) and (2), we get a simple and accurate approximation of the 2-D electric fields along the electric field line M CM , i.e., It is also shown that (9) is a good approximation for the electric field along the electric field line M CM .…”

“…Strollo and Napoli proposed the similar 2-D model by a charge superposition method and numerically demonstrated that the minimum specific on-resistance could be obtained when the SJ voltage sustaining layer is not fully depleted, and proposed a "suboptimal design method" [6]. Napoli et al and Wang et al established the vertical electric field for a charge imbalance SJ structure to get the breakdown model [7], [8].…”

“…The solid lines are simulation results, whereas the dashed lines are the results from the analytical model(8). The conditions used for simulation inFig.…”

Analytical Modeling of Switching Energy of Silicon Carbide Schottky Diodes as Functions of <italic>dI <inline-formula><tex-math notation="LaTeX">$_{\bf DS}$</tex-math></inline-formula>/dt</italic> and Temperature

“…The models that have previously been developed to understand the transient behavior of silicon PiN diodes during reverse recovery, including physics-based models [21], [22], analytical models [23]- [25], Saber Models [26] and PSPICE Models [27] are not extendable to SiC Schottky diodes since the latter is unipolar [28]. Models for parameter extraction in SiC Schottky diodes [29] provide valuable information about understanding the static behavior of the diodes, however, they lack the capability of modeling dynamic characteristics and switching energy.…”