Recent Power Semiconductor Devices Technologies for a Future Smart Society

Transcription

1 Recent Power Semiconductor Devices Technologies for a Future Smart Society Prof. Noriyuki Iwamuro Faculty of Pure and Applied Sciences University of Tsukuba 1

2 Image of Future Smart City Smart city: Energy saving city for making full use of advanced technology such as IT or power devices 2

3 Power Semiconductor device in Toyota Prius PCU AC Power Semiconductor Devices DC Battery DC- Chopper Inveter Motor Inverter Gen. Others Power Conversion from DC to AC Engine 1200V/400A 3

4 Power Semiconductor device in Wind turbine Converter Gen. Power Line Power Conversion from AC to AC Power Semiconductor Devices (IGBT Module) 1700V/450A~1000A 1000A 4

5 Power electronics applications Air Conditioner Robotics Train Home Appliance UPS EV, HEV Bottom line for the power conversion/power devices 1)Higher efficiency and 2)Higher ruggedness Superior power devices are strongly required 5

6 Application Field of Power Devices( ) Silicon(Si)-MOSFET, Si-IGBT widely accepted 10M 1M Frequency(Hz) 100 k 10k 1k Audio SMPS MOSFET IGBT MDL Automotive Inverter Air conditioner Inverter Servo, Robotics Home appliance UPS Railway GTO Thyrisitor Powerline k 10 k 100 k 1M 10M 100 M Device Capacity (VA) 6

7 Improvement of Si-IGBT On-state voltage(on resistance): 50%, Die size: 70 70% 2nd Gen. 3rd Gen. 1200V/100A Device (Courtesy: Fuji Electric) Area=1 A= th Gen. On-state voltage(v) A=0.71 5th Gen. A=0.43 6th Gen. A=0.31 Year 7

8 After 2003, Improvement of thin wafer slow down In 2015, thickness is comparable to that in 2003 Breakdown voltage is not sustainable when we thin the wafer more Si limit! Limitation of Thin Wafer Technology thickness チップ厚さ ( u m ) V 1700V 600V (Year) ( 年 ) 8

9 Ge Change of semiconductor device materials First semiconductor material μe=3900 cm2/vs μh=1900 cm2/vs Eg = 0.66eV Operation Temp Si Eg = 1.12eV Operation Temp 150 All application Fast switching High Temperature operation GaN Diamond SiC 2015 Wide Band Gap Materials GaAs Eg = 1.42eV Operation temperature LD, LED High speed(hemt, MESFET) complicated process difficulty of bipolar device No good passivation film 9

10 World focusing on the WBG semiconductors US President B. Obama announced (Jan. 2014) the advanced manufacturing institute for energy-efficient efficient wide band gap semiconductor National project of SIP(Strategic Strategic Innovation Promotion Program)launched for development of wide band gap semiconductor in

11 Why Wide Band Gap materials? Advantage of WBG device over Si one SiC Device Thinner n- layer(1/10 of Si) High impurity density Lower RonA Also, higher temp. applicable V B =E c W m /2 N D =εec 2 /2qV B R=W m /qμn D W m = 1/10 Ron = 1/300 11

12 Why SiC power devices? 1. Limit of Si power devices 2. Requirement from new application field 1High temperature operation(over over 200 ) 2Under very severe environment(ex.space ex.space) 3Small and down size 4Higher efficiency 3. History, development achievement 12

13 Merit for high temp. operation Hybrid Car(Lexus LS600h) HV Inverter system(pcu) Ref. Denso Corp. Si IGBT Inverter SiC MOSFET Inverter Abolition of exclusive cooling system for Inverter Common use of radiator coolant Less space Smaller size 13

14 SiC Power device mass production by Φ6 wafer Fuji Electric started the SiC device mass production in Oct, (Matsumoto, Nagano, Japan) 14

15 SiC power electronics product application (Ref:Web of Council for Science, Technology and Innovation ) Application for Railway SiC Inverter installed in Tokyo Metro Ginza Line (Si-IGBT+SiC IGBT+SiC-SBD) SBD) (Produced by Mitsubishi Electric) SiC Inverter Power loss reduction: 40% 15

16 SiC power electronics product application MEGA Solar PCS which 1200V All SiC-MOSFET module is installed. (Fuji Electric, May. 2014) Features: Higher efficiency and small size Efficiency 98.8% Volume 20% reduction (SiC-MOSFET+SiC MOSFET+SiC-SBD) SBD) (Ref. Web of Nikkei Technology On-line) Also, Toyota announced the SiC power devices will be installed in the new HEV in

17 Issues to be solved in SiC 1. Threshold instability after applying Vg 2. Improvement of on-state resistance Measured results of the Vth shift after applying Vg=+20V, Comparison of Vbr-RonA in various power (M.Firuhashi et al(mitsubishi), ISPSD2013, pp.55) ~0.3V RonA(mΩcm 2 ) Vth shift is still observed Breakdown Voltage(V) RonA: Large difference between measured data and the theoretical limit 17

18 Influence of interface states on MOSFET Electron trapped at the interface states electrons scattered 1μmos degrades2vth increase Gate Electrode SiO 2 - electrons interface SiC qv s qv f Negative charged trapped at the interface states E C E i E FS Gate Source - E V n p - p+ qv G Acceptor E FM x d (a)energy band diagram (b)cross section of MOSFET 18

19 GaN power electronics product application Solar PCS(4.5kW) in which 600V GaN-HEMT devices are installed. (Yaskawa Electric, Dec. 2014) Solar PCS (4.5kW) Features: Higher efficiency and small size Efficiency 98.% Volume 50% reduction Low noise (Ref. Web of Yaskawa Electric) 19

20 GaN-HEMT Devices(IEDM2014 IEDM2014) Device structure GaN on Si HEMT+Si-MOS MOS Cascode Wafer Φ6GaN on Si HEMT 20

21 Classification of SiC and GaN devices Current flow Good SiC wafer applicable SiC on SiC structure Electrode No good GaN wafer applicable Electrode GaN on Si structure Current flow Electrode SiC EPI GaN SiC substrate Buffer(High resistance) Sub.(Si) Electrode SiC: Vertical Device Current flows in the whole region High current GaN: Lateral Device Current flows at the surface Low current For high power device, vertical structure is suitable SiC: High power, GaN: Low/Medium power 21

22 Summary 1. Present Status of Power Semiconductor Devices 2. Recent Progress of SiC Power Devices SiC-MOSFET Module application just started for high power application 3. Recent Progress of GaN Power Devices GaN-HEMT application just started for low/medium power application 22

23 Thank you for your kind attention 23