Gate-drain charge analysis for switching in power trench MOSFETs

For the switching performance of low-voltage (LV) power MOSFETs, the gate-drain charge density (Q/sub gd/) is an important parameter. The so-called figure-of-merit, which is defined as the product of the specific on-resistance (R/sub ds,on/) and Q/sub gd/ is commonly used for quantifying the switchi...

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Bibliographic Details
Published in:IEEE transactions on electron devices 2004-08, Vol.51 (8), p.1323-1330
Main Authors: Hueting, R.J.E., Hijzen, E.A., Heringa, A., Ludikhuize, A.W., Zandt, M.A.Ai
Format: Article
Language:English
Subjects:
Charge
DC-DC power conversion
Depletion
Devices
Electric breakdown
Inversions
Mathematical models
MOSFETs
Power MOSFETs
Semiconductor device modeling
Switches
Switching
Trenches
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Summary:For the switching performance of low-voltage (LV) power MOSFETs, the gate-drain charge density (Q/sub gd/) is an important parameter. The so-called figure-of-merit, which is defined as the product of the specific on-resistance (R/sub ds,on/) and Q/sub gd/ is commonly used for quantifying the switching performance for a specified off-state breakdown voltage (BV/sub ds/). In this paper, we analyzed the switching behavior in power trench MOSFETs by using experiments and simulations, focusing on the charge density Q/sub gd/. The results of this analysis can be used for further optimization of these devices. The results show that the Q/sub d/ can be split into three charge contributions: accumulation, depletion, and inversion charge. It is shown that the inversion charge is located mainly underneath the trench bottom. The accumulation and depletion charge contribute each about 45% in conventional LV trench MOSFETs and can be reduced by using a thick bottom oxide in a shallow trench gate just extending in the drift region. Further, we derived an analytical model for calculating the Q/sub gd/, that takes into account the geometry dependence.
ISSN:0018-9383
1557-9646
DOI:10.1109/TED.2004.832096