2Nd-Generation SJ-MOSFET for Automotive Applications

technology improvement mounted electric (HEVs), In tion vehicles Efficient 1. making stringent smaller. ture such strong ing sion tors power products. has the ries developed loss andlownoise. loss Series” FET product forautomotiveapplications. jump *

Electronic DevicesBusinessGroup, FujiElectricCo.,Ltd. addition, (1)-(3) Recently, Introduction In This “Super ficiency ofthepowerconversionequipmentforautomotiveapplications. ef- enhanced and reduction size to contributes product this of use The switching. turn-off during voltage jumping and loss switching between trade-off the improving while loss conduction reduces which Series,” S1A MOS J “Super tions applica- automotive for SJ-MOSFET 2nd-Generation the developed has Electric Fuji recently, More loss. switching low and resistance on-state low their by characterized structure superjunction a adopt that applications automotive for be to required being are products MOSFET compact, lowlossandnoise.FujiElectrichasdevelopedlaunchedthe“SuperJMOSS1ASeries,”aproduct power Accordingly, vehicles. electric hybrid as such vehicles friendly loss; as (MOSFETs) than to equipment to for as in order ” demand metal-oxide-semiconductor achieve environmental (S2A There has been increasing demand for smaller power conversion equipment and better fuel efficiency in eco- in efficiency fuel better and equipment conversion power smaller for demand increasing been has There be vehicles the in plug-in automotive 2nd-Generation SJ-MOSFET for Automotive paper the automotive on use in represented and that Accordingly, the Semiconductor J 2011, (power compact, these to to 2014, vehicle MOS drain-source Series) in in Applications “Super JMOSS2A Series” of users’ 1st-Generation low of meet presents improve to hybrid are fuel TABIRA, Keisuke used the which the (EVs) the types make S1A electronics) we on-state also DC-DC cabin these applications efficiency, automotive environmental electric S1A regulations highly in that developed Series” electric by adopted power of the have the automotive these required switching vehicles voltage requirements, more Series features resistance hybrid comfort 2nd-Generation converters efficient power been “Super (S1A conversion is types vehicles and a spacious, market, gaining and “Super superjunction become and V to field-effect directly DS Series), elements power attracting electric power lower of awareness of of be

* and J commercialized

suppresses (V and passengers power (P-HEVs) and the compact, MOS DS Fuji J increasingly importance. eco-friendly low equipment, leads NIIMURA, Yasushi conduction conversion there

converters MOS a surge) low-noise chargers, SJ-MOS- batteries vehicles discrete such transis- Electric conver- switch- S1 atten- struc- rises. to T C A R T S B A is S2A and low the Se- an by as in a Fig.1 GeneratedlossofMOSFET inPFCcircuitofcharger classified circuit in tion may occurduetogateoscillation,whichposesanissue. increase consisting 2. turn-off switching. improve ing be both generated area, order increasing reduced a reduced. Figure 1 Figure Accordingly, Design Concept the power loss the * R to

of on on-state by reduce the ∙ during by A a into conduction of MINAZAWA, Hiroshi (a) PFCcircuit MOSFET loss the , increasing charger reducing efficiency shows turn-on to The MOSFET conduction switching less of the the turn-off resistance, conduction a PFC a switching than S2A for loss in power breakdown loss the of the a automotive Series P power power switching, speed that on-state loss ton switching and MOSFET and (b) GeneratedlossofMOSFET

loss and loss of P aims on factor conversion switching

Generated loss (%) on of the 100 turn-off the is 60 70 80 90 10 20 30 40 50

causes the 0 resistance and the applications. * reduced and

to speed. switching S1A correction can turn-off reduce loss switching false V loss loss Series, equipment, DS be generated by However,

per surge P roughly conduc- turn-on side P P P toff should loss lower- (PFC) on ton toff . unit The loss and 265 To in to is

issue: Power Semiconductors Contributing in Energy Management 2 improve the trade-off by reducing VDS surge without 15 mΩ∙cm , which is 25% lower than that of the S1A increasing switching loss. Series, 20 mΩ∙cm2.

3. Features 3.2 Reduction of VDS surge As described in Section 2, reduction of switching 3.1 Reduction of conduction loss loss and reduction of VDS surge are in a trade-off rela- Since lowering the on-state resistance is effective tionship, and improving the relationship is an issue. in reducing the conduction loss, we have worked on de- The S2A Series reduces VDS surge without increasing creasing Ron∙A of the S2A Series. switching loss to improve the trade-off. The superjunction structure applied to the S1A We often cannot design an ideal circuit pattern for and S2A Series ensures withstand voltage with the a power board due to the restrictions that we have to entire drift layer by providing the n-type and p-type re- use existing power circuit patterns, part layouts, and gions, which constitute the drift layer, alternately laid other conditions. In that case, if the circuit has large out. This allows the impurity concentration of the n- inductance and inappropriate drive conditions and type regions in the drift layer to be increased even with circuit constants, simply replacing the MOSFETs in- the same withstand voltage as that of the conventional creases VDS surge, so that false turn-on may occur due planar type. Thus, Ron∙A can be significantly reduced to gate oscillation during switching. (see Fig. 2(4)-(8)). As an example, we used a chopper circuit to com- We have improved the technology of the impurity pare the S1A Series and S2A Series. For ease of com- diffusion process to increase the impurity concentra- parison, this circuit was not optimized in terms of the tion in the n-type regions. This reduces the resistance drive conditions and circuit constants according to the value of the drift layer, and we have further reduced MOSFETs to use. Figure 4 shows the turn-off switch- Ron∙A of the S2A Series to lower than that of the S1A ing waveforms for the respective series. With the S1A (9),(10) Series . Figure 3 shows a comparison of Ron∙A be- Series, VDS surge increases, causing a false turn-on tween the S1A and S2A Serieses that have a with- [see Fig. 4 (a)]. stand voltage of 600 V. Ron∙A of the S2A Series is Power converters for automotive applications are mounted in the engine room and often used in a high- temperature environment, and the threshold voltage Gate Source VGS(th) has negative temperature characteristics. This leads to the assumption that FETs to be used are sus-

+ n P+ p

Drift layer n p n p n p n

VDS: 100 V/div

False on n+

Drain ID: 10 A/div

Fig.2 Superjunction structure t: 50 ns/div

(a) S1A Series (600-V withstand voltage model) 25

20 VDS: 100 V/div ) 2 25% reduction 15 (m Ω∙ cm

∙ A 10

on ID: 10 A/div R 5 t: 50 ns/div

0 (b) S2A Series S2A Series S1A Series

Fig.4 Turn-off‌ switching waveforms (external gate resistance Fig.3 On-state resistance per unit area Ron∙A Rg: 2 Ω)

266 FUJI ELECTRIC REVIEW vol.62 no.4 2016 ceptible to gate oscillation and hence prone to false design of a high-efficiency power supply. turn-on. It is considered effective to raise VGS(th) to It also expands the selection of element withstand suppress false turn-on. However, increasing VGS(th) voltages available, which has the effect of allowing alone causes VDS surge to increase at the time of turn- the use of an element with a lower withstand volt- off switching, leading to the possibility of a false turn- age, or lower on-state resistance, than what has been on due to gate oscillation. used. Accordingly, we have commercialized the 500-V The S2A Series have taken the countermeasures, and 400-V withstand voltage models for the S2A Se- including the optimization of VGS(th) and the integra- ries, which had consisted of the 600-V and 650-V ones, tion of the gate resistance Rg into the chip, which in- equal voltages of the S1A Series models. crease VGS(th) while reducing VDS surge to prevent false turn-on [see Fig. 4 (b)]. 3.3 Reduction of loss under light load conditions Figure 5 shows the characteristics of the external To extend the lifespan of batteries, DC-DC convert- gate resistance Rg and VDS surge evaluated by using ers for automotive applications are driven under light the chopper circuit. When Rg is low, the S2A Series load conditions in most of the lifetime operation. For shows a VDS surge-reducing effect as compared with that reason, reducing the loss under light load condi- the S1A Series. As shown in Fig. 6, the S2A Series tions significantly contributes to an improvement in shows a lower turn-off switching loss Etoff than that of fuel efficiency. When the DC-DC converter is oper- the S1A Series at the same VDS surge. This indicates ated under light load conditions, the current running that the trade-off between Etoff and VDS surge has im- through the MOSFET is small. Thus, the ratio of loss proved. Eoss generated during charge and discharge to the out- As explained up to now, when the MOSFET that put capacity Coss accounts for a large proportion. Ac- has conventionally been used is replaced with a new cordingly, with the S2A Series, the total gate electric one, reduction of VDS surge eliminates the need for the charge QG has been reduced by optimizing the surface user to change the circuit pattern or make significant structure to successfully reduce Eoss by approximately changes to component constants. This facilitates the 30% from that of the S1A Series (see Fig. 7). The switching loss of the S2A Series has been reduced by improving the trade-off between Etoff and VDS 650 Management issue: Power Semiconductors Contributing in Energy surge and reducing Eoss. This allows the power conversion circuit to be run at a higher frequency than con- 600 ventionally done, which permits use of a smaller trans- former, leading to miniaturization of power conversion 550 S1A Series equipment. surge (V) 500 DS 3.4 Quality for automotive applications V Products for automotive applications are required S2A Series 450 to have withstand capability against temperature changes. For the S1A and S2A Series, we worked on 400 0 5 10 15 optimizing the chip thickness, the conditions of solder- Rg (Ω) ing under the chip during assembly, and the adhesion between the molding resin and lead frame. These Fig.5 External gate resistance Rg and VDS surge characteristics measures significantly improved the temperature cycle capability as compared with consumer products with

1,000 25 900

20 800 S1A Series Approx. 30% (µJ) 700 15 reduction toff (µJ)

E S2A Series

600 oss

E 10 500 5 400 450 500 550 600 650 VDS surge (V) 0 S2A Series S1A Series

Fig.6 ‌Turn-off switching loss Etoff and VDS surge trade-off characteristics Fig.7 Loss generated in charge and discharge Eoss

2nd-Generation SJ-MOSFET for Automotive Applications “Super J MOS S2A Series” 267 mΩ, contributes to miniaturization of power conversion 10,000 S1A Series, equipment in terms of the package size. S2A Series Products with an on-state resistance of 25.4 to 160 D2-Pack mΩ with the TO-247 package and 81 to 160 mΩ with 1,000 T-Pack are included in the product line. We have also launched the fast recovery diode (FRED) type “Super J Conventional product MOS S2FDA Series,” which integrates faster built-in (consumer product) 100 diodes than those incorporated in the S2A Series.

5. Postscript

Temperature cycle capability (cycles) 10 0.001 0.01 0.1 The 2nd-Generation SJ-MOSFETs for automo- 1/ ∆T (K−1) tive applications “Super J MOS S2A Series” is a line of products achieving both low loss and reduced VDS Fig.8 Temperature cycle capability surge. They make significant contributions to efficiency improvement and miniaturization of power con- the same package and the same chip size (see Fig. 8). version equipment. In the future, in order to meet increasingly ad- 4. Product Line-Up and Characteristics vanced market needs, we intend to work on chip miniaturization and on-state resistance reduction. We Table 1 shows the product line-up of the S2A Series will do so by expanding the product line with a wider and major characteristics. In addition to improving selection of withstand voltages and further refining the the on-state resistance and switching characteristics superjunction structure to develop high-performance, described up to now, compliance with the AEC Q101 high-quality discrete products for automotive applica- standard, which is a standard for reliability assurance tions. of automotive discrete products, is guaranteed for the entire product line. References While the S1A Series using the TO-247 package (1) Tamura, T. et al. “Super J-MOS” Low Power Loss Su- has a minimum value of the on-state resistance of perjunction MOSFETs. FUJI ELECTRIC REVIEW. 40 mΩ for 600-V withstand voltage models, the S2A 2012, vol.58, no.2, p.79-82. Series achieves 25.4 mΩ. The small surface-mount (2) Tamura, T. et al. “Reduction of Turn-off Loss in 600 device (SMD) T-Pack (D2-Pack) of the S1A Series has V-class Superjunction MOSFET by Surface Design”, an on-state resistance of 145 mΩ with 600-V withstand PCIM Asia 2011, p.102-107. voltage models. The S2A Series, which can achieve 79 (3) Watanabe, S. et al. “A Low Switching Loss Superjunc- tion MOSFET (Super J-MOS) by Optimizing Surface Table 1 ‌“Super J MOS S2A Series” product line-up and major Design”, PCIM Asia 2012, p.160-165. characteristics (4) Fujihira, T. “Theory of Semiconductor Superjunction TO-247 T-Pack Devices”, Jpn. J. Appl. Phys., 1997, vol.36, p.6254- (D2-Pack)

R DS (on) 6262. VDS ID FRED max. (5) Deboy, G. et al. “A New Generation of High Voltage MOSFETs Breaks the Limit Line of Silicon”, Proc. 400 V 60 mΩ 42 A Available — FMC40N060S2FDA IEDM, 1998, p.683-685. 500 V 71 mΩ 39 A Available FMY50N071S2FDA FMC50N071S2FDA (6) Onishi, Y. et al. 24 m· cm2 680 V Silicon Superjunction 25.4 mΩ 95 A FMY60N025S2A — MOSFET”, Proc. ISPSD’02, 2002, p.241-244. 2 40 mΩ 66 A FMY60N040S2A — (7) Saito, W. et al. “A 15.5 m· cm - 680 V Superjunction

70 mΩ 39 A FMY60N070S2A — MOSFET Reduced On-Resistance by Lateral Pitch

79 mΩ 37 A FMY60N079S2A FMC60N079S2A Narrowing”, Proc. ISPSD ’06, 2006, p.293-296. (8) Oonishi, Y. et al. Superjunction MOSFET. FUJI ELEC- 81 mΩ 36 A Available FMY60N081S2FDA FMC60N081S2FDA TRIC REVIEW. 2010, vol.56, no.2, p.65-68. 600 V 88 mΩ 33 A FMY60N088S2A FMC60N088S2A (9) Watanabe, S. et al. 2nd-Generation Low-Loss SJ-MOS- 99 mΩ 29 A FMY60N099S2A FMC60N099S2A FET “Super J MOS S2 Series”. FUJI ELECTRIC RE- 105 mΩ 28 A Available FMY60N105S2FDA FMC60N105S2FDA VIEW. 2015, vol.61, no.4, p.276-279. 125 mΩ 23 A FMY60N125S2A FMC60N125S2A (10) Sakata, T. et al. “A Low-Switching Noise and High- 133 mΩ 22 A Available FMY60N133S2FDA FMC60N133S2FDA Efficiency Superjunction MOSFET”, Super J MOS® S2, 160 mΩ 18 A FMY60N160S2A FMC60N160S2A PCIM Asia 2015, p.419-426.

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