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Steady State Total Dose Irradiation
Test Report
FBG10N05
ABSTRACT
April 14th, 2016
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Copyright (C) 2017 Freebird Semiconductor
This document contains information proprietary to Freebird Semiconductor, and it is issued on condition that it is received and held in confidence.
Neither it nor the information herein shall be reproduced, sold, lent, disclosed or used for any purpose other than that for which it has been issued
without written authority of Freebird Semiconductor.
Contents
1.0 Executive Summary ........................................................................................................................................................... 3
1.1 Test Results Summary ................................................................................................................................................... 3
2.0 Background ....................................................................................................................................................................... 3
3.0 References ........................................................................................................................................................................ 4
4.0 Handling Precautions. ....................................................................................................................................................... 4
5.0 Procedure .......................................................................................................................................................................... 5
6.0 Gamma Test Results.......................................................................................................................................................... 6
6.1 Bias Circuit..................................................................................................................................................................... 6
6.2 Dosimetry. ..................................................................................................................................................................... 7
Fig 3. Dosimeter Prototype Board .......................................................................................................................................... 7
Table 1. Dose Rate and Uniformity ......................................................................................................................................... 7
7.0 Gamma test results ........................................................................................................................................................... 8
7.1 Total Dose Response. .................................................................................................................................................... 8
7.1.1
Gate-to-Source Leakage Current (IGSS) Responses .......................................................................................... 8
7.1.2
Drain-to-Source Leakage Current (IDSS) Response ......................................................................................... 10
7.1.3
Threshold Voltage (VTH) Response ................................................................................................................ 11
7.1.4
On-State Resistance (RDSON) Response .......................................................................................................... 12
8.0 Summary ......................................................................................................................................................................... 12
Appendix A – Equipment list ................................................................................................................................................. 13
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1.0 Executive Summary
Freebird evaluated the radiation performance of the FBG10N05X 100 Volts 5 Ampere Enhancement Gallium
Nitride power switching HEMT FET at VPTRad according to the test plan FBS-P-603-16-008. This report
covers the total dose (Gamma) characterization portion of the test plan for wafer lot C5A08H47.2 wafer
RLUJP054. Section 5 discusses the test procedure; and Section 6.0 discusses the test results. Appendix A
provides test notes and setup information from VPTRad.
Freebird Semiconductor performed gamma irradiations under two different bias conditions:
Bias 1: VGS = 5 V and VDS = 0 V (On-State Bias)
Bias 2: VGS = 0 V and VDS = 80 V (Off-State Bias)
1.1 Test Results Summary
Two packages per bias were characterized (S/N 3, 4, 5 and 6) in accordance with Freebird test plan FBS-P603-16-008. No failures where observed up to an accumulated ionizing dose of 1.0 Mrad using a nominal
dose rate of 135rad/sec. None of the electrical parameters exceeded the specified limits of the datasheet
due to gamma irradiation; the measured electrical parameters after each incremental dose were:
-
Gate-to-Source leakage current (IGSS)
Drain-to-Source leakage current (IDSS)
Threshold voltage (VTH)
On-state resistance (RDSON)
2.0 Background
The FBG10N05 is an enhancement mode Gallium Nitride High Electron Mobility Transistor (HEMT)
developed by EPC for Freebird under a dedicated source controlled and in Fab screening. The FBG10N05 is
the smaller size die of Freebird 100V platform and was screened to a total dose level of 1 Mrad.
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3.0 References
The major applicable documents, used to perform this gamma irradiation characterization are:
MIL-PRF-19500
General Specifications for Semiconductor Devices
MIL-STD-750D
Test Methods for Semiconductor Devices
Method 1019
Steady State Total Dose Irradiation Procedure
Method 3421
On-State Resistance
Method 3403
FET Threshold Voltage Measurement
Method 3405
Drain to Source On-State Voltage
Method 3411
Gate to Source Leakage Current
Method 3415
Drain to Source Leakage current
FBS-P-603-16-008
FBG10N05
VPTRad
Freebird Semiconductor Test Plan
Freebird Datasheet Rev Q
VPTRad operating instructions
4.0 Handling Precautions.
The following handling precautions were observed.
4.1 Proper ESD handling the devices according to their rating
4.2 Maximum rated voltages during irradiation were not exceeded
4.3 Devices were stored within antistatic boxes
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5.0 Procedure
Test conditions were performed as specified by Freebird Test Plan FBS-P-603-16-008 using the applicable
test circuit. Irradiations were performed at the ambient temperature of the irradiator system. Figure 1
shows the insitu bias circuit as defined in the test plan.
Bias 1: VGS = 5 V and VDS = 0 V (On-State Bias)
Bias 2: VGS = 0 V and VDS = 80 V (Off-State Bias)
Devices were placed in the (Co-60 Gamma Cell) irradiator with the appropriate bias applied. The devices
were then irradiated to the following accumulated dose levels.
a) 0 kRad
b) 300 kRad
c) 500 kRad
d) 1000 kRad
Upon completion of each exposure level, the devices were removed from the irradiator, electrically tested,
and returned to the gamma irradiator for the next exposure level.
Figure 1. Test circuit for insitu TID testing
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6.0 Gamma Test Results
6.1 Bias Circuit.
Freebird used VPTRad the Standard TO-254 irradiation board which conformed to the test circuit
shown in figure 1.
Figure 2 shows a picture of the VPTRad To-254 test board.
Figure 2. Photograph of Insitu Bias Board Used during TID Irradiations and Freebird test coupon.
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6.2 Dosimetry.
Radiation dosimetry at VPT Rad is performed using an alanine Electron Paramagnetic Resonance (EPR)
dosimetry system. The EPR spectrometer uses a variable magnetic field to detect the energy level
transitions of unpaired electrons at specific resonant frequencies. The radiation dosimeters for the EPR
system incorporate the amino acid alanine. When exposed to ionizing radiation, the alanine molecule
forms a very stable free radical that is detectable by the EPR system. The EPR signal strength is then
converted into TID dose via a NIST calibration that is performed over the operational ranges of the
system. Table 1 lists the response of the dosimeters for a two back to back prototype boards as shown
in fig 3. The average dose was 133 rad/sec
Fig 3. Dosimeter Prototype Board
Table 1. Dose Rate and Uniformity
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7.0 Gamma test results
7.1 Total Dose Response.
Four packages were characterized to Gamma radiation using a Co-60 Gamma Cell Irradiator at VPTRad.
A nominal dose rate of 135 rad/sec was used. The sections below will discuss the testing of each of the
six electrical parameters and their test results.
7.1.1 Gate-to-Source Leakage Current (IGSS) Responses
The average gate-to-source leakage current response of these four devices is shown in Figures
3a and 3b. Figure 3a depicts the forward leakage current with an applied gate of +5V and Figure
3b depicts the reverse gate to source leakage current with an applied gate of -5V. This
measured response showed that, for any of the two bias conditions, the gate-to-source leakage
current remained below the 2mA and 60µA specification limit up to a total ionizing dose of 1
Mrd.
Figure 3a. Forward Gate-to-Source Leakage Current Response to Total Ionizing Dose
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Figure 3b. Reverse Gate-to-Source Leakage Current Response to Total Ionizing Dose
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7.1.2 Drain-to-Source Leakage Current (IDSS) Response
The drain-to-source leakage current response of the four devices is shown in Figure 4. The
drain-to-source leakage current was measured at a drain voltage of 80 volts. The measured
response clearly showed that, for the two bias conditions, the drain-to-source leakage current
did not exceed the 60 µA specification limit up to a total ionizing dose of 1 Mrad.
Figure 5. Drain-to-Source Leakage at 80% rated Voltage Response to Total Ionizing Dose
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7.1.3 Threshold Voltage (VTH) Response
Figure 6 shows the measured threshold voltage response of the four devices. Threshold voltage
was measured at a drain current of 2 mA for all bias conditions. The measured response
showed that the threshold voltage did not exceed the 2.5V specify limit up to 1Mrad. Drain to
Source bias was very stable with very little shift while the gate to source showed a slight
increase in threshold voltage.
Figure 6. Threshold Voltage Response to Total Ionizing Dose
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7.1.4 On-State Resistance (RDSON) Response
Figure 7 shows the measured on-state resistance response of the four devices. On-state
resistance was measured at a gate voltage of 5 V and a drain current of 5 A. The measured
response clearly shows an increase in the on-state resistance the first 100 kRad and then
stabilizes as the devices are further subjected to gamma radiation; but still below the 32mΩ
specification limit. The observed increase in on-state resistance has been attributed to the
dynamic Rdson of the GaN technology under DC bias.
Figure 7. On-State Resistance Response to Total Ionizing Dose
8.0 Summary
Four devices were characterized (S/N 3, 4, 5, and 6). No failures where observed up to an accumulated
ionizing dose of 1.0 Mrad using a nominal dose rate of 135 rad/sec. Measured electrical parameters after
each incremental dose did not exceed the specified electrical parameters in the datasheet.
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Appendix A – Equipment list
Insitu bias Irradiation:
Keithley 2400
Keithley 2400
(Drain Bias Voltage)
(Gate Bias Voltage)
Electrical Measurements
STI5000
Custom Boards
VPTRad custom Insitu Bias Board
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