SiGe Semiconductor Devices for Cryogenic Power Electronics

1
SiGe Semiconductor DevicesforCryogenic Power
Electronics
Electrochemical Society Seventh International
Symposium on Low Temperature Electronics
14 October 2003, Orlando, Florida
2
R. R. Ward, W. J. Dawson, L. Zhu, R. K.
Kirschman GPD Optoelectronics Corp., Salem, New
Hampshire O. Mueller LTELow Temperature
Electronics, Ballston Lake, New York R. L.
Patterson, J. E. DickmanNASA Glenn Research
Center, Cleveland, Ohio A. HammoudQSS Group
Inc., Cleveland, Ohio Supported by NASA Glenn
Research Center and ONR/DARPA
3
Why use SiGe?
4
Why SiGe Devices?

• Si-Based Circuits Demonstrated, but only gt 77 K
• Standard Si Bipolar Devices Cease Operation lt
  100 K
• Applications Require Operation lt 77 K, to 30
  40 K
• Possible Materials for lt 77 K are Ge and SiGe

5
Why SiGe Devices?

• SiGe Devices Can Operate to Lowest Cryogenic
  Temperatures ( 0 K)
• All Device Types Diodes, Field-Effect
  Transistors, Bipolar Transistors
• Highly Compatible with Si Processing
• Can Optimize Devices for Cryogenic Applications
  by Selective Use of Ge, Si, SiGe
• SiGe Provides Additional Flexibility through
  Band-Gap Engineering ( of Ge)

6
Development Program
7
Development Program

• Parameters
• Low power (10 W) to medium power (100 W)
• Temperature range 300 K to 20 K
• Past
• Initial SiGe diodes fabricated
• Initial SiGe heterojunction bipolars (HBTs)
  fabricated
• Future
• MOSFETs (lateral, vertical)
• Power HBTs (vertical)
• IGBTs (lateral, vertical)

8
SiGe Cryo Power Diodes
9
SiGe Cryo Power Diodes - Design
P SiGe
Metal
N Si epi
N
N Si
(N implant)
Metal
10
SiGe vs Si Power Diodes - Forward
11
SiGe vs Si Power Diodes - Forward
12
SiGe Cryo Power Diodes - Forward Voltage
13
SiGe Cryo Power Diodes - Forward
14
SiGe Cryo Power Diodes - Forward
15
SiGe Cryo Power Diodes - Forward Voltage
16
SiGe Cryo Power Diodes - Reverse
17
SiGe Cryo Power Diodes - Reverse
18
SiGe Cryo Power Diodes - Reverse Recovery
19
SiGe Cryo Power Diodes - Reverse Recovery
20
SiGe Cryo Power Diodes - Results

• N on P and P on N, single and double epi
• Measured to 77 K operate to ?? K
• Forward V less than Si at low med forward I
• Imax gt 10 A (300 77 K)
• Reverse breakdown V gt100 V (300 77 K)
• Reverse recovery decreases at 77 K

21
SiGe Cryo Heterojunction Bipolar Transistors
(HBTs)
22
SiGe Cryo Power HBTs - Design
N-P-N (N/P/N-/N)
23
SiGe Cryo Power HBTs - 300 K
24
SiGe Cryo Power HBTs - 80 K
25
SiGe Cryo Power HBTs - 80 K
26
SiGe Cryo Power HBTs - 80 K
27
SiGe Cryo Power HBTs - 40 K
28
SiGe Cryo Power HBTs - 40 K
29
SiGe Cryo Power HBTs - Results

• Initial fabrication
• NPN
• Operate down to 40 K
• Power 5 W, limited by package
• I max gt 0.4 A (300 40 K)
• V forward breakdown gt30 V (300 40 K)
• Need improved contacts

30
Cryo Power SiGe Devices - Plans

• HBTs
• Improve HBT contacts, extend operation to 20 K
• Larger area, I max to 10 A (300 20 K)
• V forward breakdown gt100 V (300 20 K)
• High-power cryogenic packaging
• Additional Devices
• MOSFETs
• IGBTs
• Medium power, 300 20 K operation

31
Summary

• Cryogenic power electronics is needed for
  spacecraft going to cold environments and for
  space observatories
• Temperatures may be as low as 30 40 K
• We are developing SiGe devices specifically
  for cryogenic power applications
• We have made initial SiGe cryo power diodes
  and HBTs
• We plan to improve the diode and HBT
  characteristics and to develop MOSFETs and IGBTs