Innovative 3D integration of power MOSFETs for synchronous buck converters

Author(s):  
Juan A. Herbsommer ◽  
J. Noquil ◽  
O. Lopez ◽  
D. Jauregui
2008 ◽  
Vol 2008 ◽  
pp. 1-9 ◽  
Author(s):  
Yali Xiong ◽  
Xu Cheng ◽  
Xiangcheng Wang ◽  
Pavan Kumar ◽  
Lina Guo ◽  
...  

This paper investigates the performance perspectives and theoretical limitations of trench power MOSFETs in synchronous rectifier buck converters operating in the MHz frequency range. Several trench MOSFET technologies are studied using a mixed-mode device/circuit modeling approach. Individual power loss contributions from the control and synchronous MOSFETs, and their dependence on switching frequency between 500 kHz and 5 MHz are discussed in detail. It is observed that the conduction loss contribution decreases from 40% to 4% while the switching loss contribution increases from 60% to 96% as the switching frequency increases from 500 KHz to 5 MHz. Beyond 1 MHz frequency there is no obvious benefit to increase the die size of either SyncFET or CtrlFET. The RDS(ON)×QG figure of merit (FOM) still correlates well to the overall converter efficiency in the MHz frequency range. The efficiency of the hard switching buck topology is limited to 80% at 2 MHz and 65% at 5 MHz even with the most advanced trench MOSFET technologies.


Author(s):  
Ian Kearney

Abstract Accurate and lossless current sensing is vital for high performance multiphase buck converters used in the latest voltage regulation modules (VRMs). A synchronous FET onstate resistance based approach is an alternative topology to DCR based sensing and is compatible with any controller, which requires inductor current information. The MOSFET driver has built-in sense circuitry, which when co-packaged with the MOSFETs reduces total footprint and ease of design. The Powerstage embodiment virtually eliminates the parasitic inductance and resistance between Control and Synchronous power MOSFETS; and using thick copper clips substantially reduce the parasitics associated with the input supply voltage (VIN) and the switch node output voltage (VSW) connections when compared to wire-bonded solutions. This paper presents a novel investigation into a contradictory low on-resistance paradox in a stacked 3D configuration. Through analysis, characterization and simulation the author deciphered the conundrum leading to a root cause explained by a mismatch of internal gain and referenced on-resistance. Building on previous metrology improvements the innovative insights drove analysis toward root-cause.


2014 ◽  
Vol 9 (4) ◽  
pp. 671 ◽  
Author(s):  
Paolo Giammatteo ◽  
Concettina Buccella ◽  
Carlo Cecati

Author(s):  
Ian Kearney ◽  
Hank Sung

Abstract Low voltage power MOSFETs often integrate voltage spike protection and gate oxide ESD protection. The basic concept of complete-static protection for the power MOSFETs is the prevention of static build-up where possible and the quick, reliable removal of existing charges. The power MOSFET gate is equivalent to a low voltage low leakage capacitor. The capacitor plates are formed primarily by the silicon gate and source metallization. The capacitor dielectric is the silicon oxide gate insulation. Smaller devices have less capacitance and require less charge per volt and are therefore more susceptible to ESD than larger MOSFETs. A FemtoFETTM is an ultra-small, low on-resistance MOSFET transistor for space-constrained handheld applications, such as smartphones and tablets. An ESD event, for example, between a fingertip and the communication-port connectors of a cell phone or tablet may cause permanent system damage. Through electrical characterization and global isolation by active photon emission, the authors identify and distinguish ESD failures. Thermographic analysis provided additional insight enabling further separation of ESD failmodes. This paper emphasizes the role of failure analysis in new product development from the create phase through to product ramp. Coupled with device electrical simulation, the analysis observations led to further design enhancement.


2008 ◽  
Vol 600-603 ◽  
pp. 895-900 ◽  
Author(s):  
Anant K. Agarwal ◽  
Albert A. Burk ◽  
Robert Callanan ◽  
Craig Capell ◽  
Mrinal K. Das ◽  
...  

In this paper, we review the state of the art of SiC switches and the technical issues which remain. Specifically, we will review the progress and remaining challenges associated with SiC power MOSFETs and BJTs. The most difficult issue when fabricating MOSFETs has been an excessive variation in threshold voltage from batch to batch. This difficulty arises due to the fact that the threshold voltage is determined by the difference between two large numbers, namely, a large fixed oxide charge and a large negative charge in the interface traps. There may also be some significant charge captured in the bulk traps in SiC and SiO2. The effect of recombination-induced stacking faults (SFs) on majority carrier mobility has been confirmed with 10 kV Merged PN Schottky (MPS) diodes and MOSFETs. The same SFs have been found to be responsible for degradation of BJTs.


1995 ◽  
Vol 35 (3) ◽  
pp. 603-608 ◽  
Author(s):  
S.R. Anderson ◽  
R.D. Schrimpf ◽  
K.F. Galloway ◽  
J.L. Titus

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