TN90004

An insight into Nexperia Power GaN technology –Applications, quality, reliability and scalabilityRev. 1.0 — 21 July 2020

technical note

Document informationInformation

ContentKeywords

GaN, FET

Abstract

In this paper we have concentrated on the Power GaN product and technology robustness, quality,reliability and volume manufacturability based on GaN on Si base material. We report here on theproduct robustness from applications and parametric point of view and qualification testing resultsof latest generation 650V GaN FETs qualified in accordance with AEC-Q101 standard. Devices
offer rated operating temperature of -55°C to +175°C and this family comes with robust gate withhigh threshold voltage which provides a high safety margin against gate-source transients. Someof the tests are performed beyond AEC-Q101 requirements

TN90004

Nexperia

An insight into Nexperia Power GaN technology – Applications, quality, reliability and scalability

1. Introduction
Most efficient power conversion requires best semiconductor devices as the fundamental building
block. Power GaN technology offers best possible efficiency. Proving performance is not inquestion for those closely following the Power GaN technology for its performance demonstrationin different applications. Providing robustness of the products in operation, quality, reliability of thetechnology and the scalability uptake in manufacturing are yet to prove. Power GaN technology
is full of challenges. In RF applications they are already successful but in high current highpower applications in high voltage, volume manufacturers need to address these challenges
to satisfaction. In this paper we’d like to share product robustness for applications, quality andreliability at high voltage and high temperatures, for the Power GaN technology.
Nexperia Power GaN technology focuses on high power applications like AC/DC, PFC, OBC, DC/
DC and Traction Inverters within 650V-900V for Automotive, Telecom, Server, storage, data centres
and industrial market sectors
WBG materials with higher critical electric field and higher mobility together give lowest RDSon(source drain on state resistance) for higher voltages and significantly better switching FOM (Figureof Merit). WBG devices as beginning to enter the market shows significant promise and takes
away many limitations naturally imposed by Si IGBT and Si SJ devices. Some of the hard switchedapplication topologies where Si SJ FETs cannot be used due to the diode reverse recovery caneasily use Power GaN FETs and take full advantage of reduced components count and higher
efficiency with simpler control schemes.
GaN HEMT (High Electron Mobility Transistor) works with the formation of 2DEG (2 Dimensional
Electron Gas) due to the spontaneous polarisation and piezoelectric polarisation combined at theinterface of GaN and AlxGa1-xN. Epi is formed on Si substrate via seed layer and a graded layer ofGaN and AlGaN layers before the pure GaN layer is grown and thin layer of AlGaN then forms the2DEG. Electron mobility in this layer is very high hence the name.
Current Power GaN FETs are of two main flavour: E-mode or single die normally off device, andD-mode or two die normally off device. Stability and leakage current of the E-mode gates areof concern but two die normally off or cascode configuration currently gives peace of mind as
the driving of these FETs are simple and robust. E-mode device drive is complex, especially forhigh voltage high power applications. For high voltage and high power applications, to avoid gate
bounce and harmful shoot through situation, need to have high gate threshold voltage and stablegate drive without worrying for over drive. This is currently not achievable with existing E-mode
technologies. The device in our presentation is two die normally off configuration

2. Product robustness
The product parameters shared here came from our 50 mΩ (typical at 25°C) 650 V device but
all our products/technology share the same common robustness. Product robustness include
parametric assurance like, high reliability gate structure (± 20 V) and high threshold voltage(Vth = 4 V) that provides a high safety margin against gate source transients induced due to thehigh drain source dv/dt, high voltage source-drain transient specification (800 V for 650 V device)
capable of handling switching transients up to 800 V reliably, rated operating range of -55 °C to 175°C with Tj(max) of 175 °C, body diode characteristics with very low VF (1.3V @ 12 A) enabling Silike freewheeling current capability without complex dead time adjustments and along with otherparametric performances are part of the product robustness of the GaN product family.

3. Quality / qualification of power GaN technology including failure modes
The latest generation 650 V GaN FETs are qualified in accordance with AEC-Q101 Rev D level
qualification tests. Results shared here are done on 50 mΩ (typical at 25 °C) 650 V device that
include 650 V, 175 °C High Temperature Reverse Bias (HTRB) tests (1000 hrs) and dynamic
RDSon shifts. In the following, the term dynamic RDSon will be used to emphasize that RDSon
measurements are made with a dynamic, switch-mode test. Temperature cycling tests (1000cycles) are performed over the range of -55°C to 150°C. High temperature (175 °C) Gate positive(+20 V) and negative (-20 V) bias tests were performed. Further life tests include high temperature
biased and unbiased humidity tests and operating life tests. These are only some of the criticaltests performed and passed to show the reliability and high quality of the technology.

TN90004

technical note

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Rev. 1.0 — 21 July 2020

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TN90004

Nexperia

An insight into Nexperia Power GaN technology – Applications, quality, reliability and scalability

3.1. HTRB
High-Temperature Reverse Bias has been performed at full rated voltage and maximum operating
temperature: 650 V and 175 °C. The condition for passing is that RDSon does not shift by morethan 20%. For GaN FETs it is important that RDSon be tested dynamically to detect any short-termchange due to charge trapping. Figure 1 shows the shift in dynamic RDSon for the test population.
Note that the maximum shift is less than 15%. An additional HTRB test was performed andpassed at 800 V for 10 hours. This voltage is well above the DC rating, but does correspond to therepetitive transient voltage rating.

R DSon(mΩ)

40Measured values
Initialmeasurements
168 hours
504 hours
1008 hours

30
20

high limit
low limit

159

157

155

153

151

149

147

145

143

141

139

137

135

133

131

129

127

125

123

121

119

117

115

Parts on test

Control parts

Fig. 1.

113

111

109

107

105

103

99

101

97

95

93

91

89

87

85

83

81

259

257

255

253

0251

10Dynamic RDSon measurement during HTRB

3.2. HTOL
High-Temperature Operating Life tests are not part of the AEC-Q101 standard, but are useful invalidating reliability of the parts under actual operating conditions. This is particularly important for
new materials, like GaN, to ensure that any new or unfamiliar failure modes are uncovered. A basic
half-bridge operating in continuous conduction mode provides the most fundamental exercise ofswitching behaviour. For this test, a number of identical half-bridge circuits were prepared using
two each of the GAN063-650WSA. These were operated continuously as synchronous-boost
converters with the following conditions:•••••

Vin = 200 V
Vout = 480 V
Pout = 800 W
Tj = 175 °C
Frequency = 300 kHz

The following graph shows efficiency of all samples during the 1,000 hour test. As may be seen,
there is no indication of degradation in any of the sample circuits. Following the tests, all devices
were tested for shifts in dynamic RDSon, leakage current, and threshold voltage. All parameters
were found to be stable, with any parametric shift within allowed levels.

TN90004

technical note

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Rev. 1.0 — 21 July 2020© Nexperia B.V. 2020. All rights reserved

3/9TN90004

Nexperia

An insight into Nexperia Power GaN technology – Applications, quality, reliability and scalability
100
Efficiency
(%)
9998
9796
950100

200

300

400

500

600

700

800

900

1000

1100

time (hours)

Fig. 2.

Efficiency of boost converters (HTOL) over 1000 hours
Ploss(W)

9Reference device (Si)

8GaN FETs

760750

1500

2250

3000
Time (hours)

Tested in hard-switched boost converter.
Operating conditions: 200 / 400 V converter operation:
175 °C; 300 kHz; 410 W
Fig. 3.

Hard switched boost converter (HTOL) @ 175 °C for 3000 hours

Failure modes addressed by life testing power GaN technology failure modes can be linked backto the life testing and extra testing performed. Like power cycling relates to wire bond heel crack,
temperature cycling address the solder degradation, HTGB look at the gate insulator failure, HTRB
addresses the field plate insulator failure while high temperature direct current test addresses thetrapped charge in gate region and consequently higher RDSon (>20% assumes fail).

4. Conclusion
Power GaN technology, though at the early stage of technology maturity offers significant
commercial viability with robustness and reliability. For scaling up, tremendous growth potential isbetter addressed with power GaN technology on Si.

TN90004

technical note

All information provided in this document is subject to legal disclaimers.

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TN90004

Nexperia

An insight into Nexperia Power GaN technology – Applications, quality, reliability and scalability

5. References
1. 600 V JEDEC-qualified highly reliable GaN HEMTs on Si substrates — T. Kikkawa et al.,2014 IEEE International Electron Devices Meeting, San Francisco, CA, 2014, pp. 2.6.1-2.6.4.
2. 650 V Highly Reliable GaN HEMTs on Si substrates over multiple generations: matching
Silicon CMOS manufacturing metrics and process control — S. Chowdhury, et al.,Compound Semiconductor Integrated Circuit Symposium (CSICS), IEEE, 2016.

6. Revision history
Table 1. Revision history
Revision
DatenumberDescription

1.0

Initial version

TN90004

technical note

2020-07-21

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 21 July 2020

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5/9TN90004

Nexperia

An insight into Nexperia Power GaN technology – Applications, quality, reliability and scalability

7. Legal information
Definitions
Draft — The document is a draft version only. The content is still underinternal review and subject to formal approval, which may result inmodifications or additions. Nexperia does not give any representations orwarranties as to the accuracy or completeness of information included hereinand shall have no liability for the consequences of use of such information.

Disclaimers
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to be accurate and reliable. However, Nexperia does not give anyrepresentations or warranties, expressed or implied, as to the accuracy
or completeness of such information and shall have no liability for theconsequences of use of such information. Nexperia takes no responsibility
for the content in this document if provided by an information source outsideof Nexperia.
In no event shall Nexperia be liable for any indirect, incidental, punitive,
special or consequential damages (including - without limitation - lostprofits, lost savings, business interruption, costs related to the removalor replacement of any products or rework charges) whether or not suchdamages are based on tort (including negligence), warranty, breach ofcontract or any other legal theory.
Notwithstanding any damages that customer might incur for any reason
whatsoever, Nexperia’s aggregate and cumulative liability towards customer
for the products described herein shall be limited in accordance with theTerms and conditions of commercial sale of Nexperia.
Right to make changes — Nexperia reserves the right to make changes
to information published in this document, including without limitationspecifications and product descriptions, at any time and without notice. This
document supersedes and replaces all information supplied prior to thepublication hereof.
Suitability for use — Nexperia products are not designed, authorized or
warranted to be suitable for use in life support, life-critical or safety-criticalsystems or equipment, nor in applications where failure or malfunctionof an Nexperia product can reasonably be expected to result in personal
injury, death or severe property or environmental damage. Nexperia and its
suppliers accept no liability for inclusion and/or use of Nexperia products insuch equipment or applications and therefore such inclusion and/or use is atthe customer’s own risk.
Applications — Applications that are described herein for any of theseproducts are for illustrative purposes only. Nexperia makes no representation
or warranty that such applications will be suitable for the specified use
without further testing or modification.
Customers are responsible for the design and operation of their applications
and products using Nexperia products, and Nexperia accepts no liability forany assistance with applications or customer product design. It is customer’ssole responsibility to determine whether the Nexperia product is suitableand fit for the customer’s applications and products planned, as well as
for the planned application and use of customer’s third party customer(s).
Customers should provide appropriate design and operating safeguards tominimize the risks associated with their applications and products.
Nexperia does not accept any liability related to any default, damage, costs
or problem which is based on any weakness or default in the customer’sapplications or products, or the application or use by customer’s third party
customer(s). Customer is responsible for doing all necessary testing for thecustomer’s applications and products using Nexperia products in order toavoid a default of the applications and the products or of the application or
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Trademarks
Notice: All referenced brands, product names, service names andtrademarks are the property of their respective owners.

TN90004

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TN90004

Nexperia

An insight into Nexperia Power GaN technology – Applications, quality, reliability and scalability

List of Tables
Table 1. Revision history......................................................5TN90004

technical note

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 21 July 2020

© Nexperia B.V. 2020. All rights reserved

7/9

TN90004

Nexperia

An insight into Nexperia Power GaN technology – Applications, quality, reliability and scalability

List of Figures
Fig. 1. Dynamic RDSon measurement during HTRB........... 3
Fig. 2. Efficiency of boost converters (HTOL) over1000 hours........................................................................... 4Fig. 3. Hard switched boost converter (HTOL) @ 175°C for 3000 hours................................................................ 4TN90004

technical note

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TN90004

Nexperia

An insight into Nexperia Power GaN technology – Applications, quality, reliability and scalability

Contents
1. Introduction................................................................... 2
2. Product robustness......................................................2
3. Quality / qualification of power GaN technology
including failure modes.....................................................2
3.1. HTRB........................................................................... 3
3.2. HTOL........................................................................... 3
4. Conclusion.................................................................... 4
5. References.................................................................... 5
6. Revision history............................................................5
7. Legal information......................................................... 6© Nexperia B.V. 2020. All rights reserved

For more information, please visit: http://www.nexperia.com
For sales office addresses, please send an email to: salesaddresses@nexperia.com
Date of release: 21 July 2020

TN90004

technical note

All information provided in this document is subject to legal disclaimers.

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