SOI in Automotive IC Design
SOI Workshop
Henk Boezen
PL Automotive SSL
NXP Semiconductors
Smart Power Technologies on SOI
Introduction Smart Power Technology
Power devices in SOI
ESD on SOI
Applications with SOI based power devices
Trends and future of SOI in Smart Power.
COMPANY CONFIDENTIAL
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Henk Boezen, SOI Workshop July 2015
Introduction
Smart Power Technologies combine digital signal processing, analogue
signal processing and Power (high voltage or high current).
These “BCD” technologies accommodate
–
–
–
–
Power control circuits
Power conversion circuits
Power drivers (LED, LCD, PDP, Audio)
Automotive applications
One of the main challenges for Smart Power is to increase energy
efficiency!
The outside world remains analogue. This requires often larger voltages /
currents offered by standard cmos.
COMPANY CONFIDENTIAL
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Henk Boezen, SOI Workshop July 2015
BCD connects to the outside world
Audio signal needs audio amplifiers.
Electrical vehicle
Transceivers in a car.
Actuators to supply current to motordriver that on its turn can actuate mirrors,
wipers etc in a car
Light sources that require analogue supply voltage or current
Video screens that need drivers for large voltages.
COMPANY CONFIDENTIAL
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Henk Boezen, SOI Workshop July 2015
Power technologies
“Technologies enabling systems or devices using high voltage, or
handle high power”
Discrete technologies
BCD technologies, that originate from analogue and bipolar world.
Embedded technologies, where high(er) voltage capability is added to
standard Cmos node.
Smart Power technologies
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Henk Boezen, SOI Workshop July 2015
SOI based BCD technologies at NXP
High Voltage:
EZ HV:
Light control IC’s
Power conversion IC’s
Power:
A-BCD:
Automotive CAN/LIN IC’s
Audio amplifiers
Display drivers
Power conversion
LED drivers
Sensor control IC’s
ABCD1
ABCD3
ABCD9
60V, 250 g/mm2
120V, 4K g/mm2
EEPROM
120V, >110K g/mm2
Full NV
COMPANY CONFIDENTIAL
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Henk Boezen, SOI Workshop July 2015
In Vehicle Networking in a Car.
Steering Wheel:
Roof:
Window Wiper Switch
Light Switches
Cruise Control Switch
Rain Sensor
Light Sensor
Sun Roof
Seat:
Seat Position Motors
Occupancy Sensor
Control Panel
Door:
Engine:
Ventilator
Sensors
Small Motors
Climate:
Airflap Position Motors
Control Panel
Mirror Motor / Switch
Window Lifter
Seat Control Switches
Door Lock
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Henk Boezen, SOI Workshop July 2015
Trends in automotive
Electrical Vehicles upcoming.
– Amount of electronics in cars is rapidly increasing
Transceiver market:
–
–
–
–
Body and comfort
Safety (airbags)
Motor management
Drive by wire
So, not more cars, however more nodes per car!
Quality demands continuously increasing!
SOI gives offers more robust products.
COMPANY CONFIDENTIAL
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Henk Boezen, SOI Workshop July 2015
SOI for Smart Power devices.
Introduction Smart power technology
Power devices in SOI
ESD on SOI
Applications with SOI based power devices
Trends and future of SOI in Smart Power.
COMPANY CONFIDENTIAL
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Henk Boezen, SOI Workshop July 2015
Key parameters of a power transistor
D
Breakdown voltage and SOA.
G
Conduction losses: low Rdson
– Resistance x area of the transistor
S
Switching losses: low Rdson x Qgd
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Henk Boezen, SOI Workshop July 2015
A trade off between Rdson and BVds
n-type
Nd
p-type
E
Ecrit (30V/um)
qNd
slope  E
z = 0r
Diode breakdown  area
On state resistance  Length x specific resistance
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Henk Boezen, SOI Workshop July 2015
A trade off between Rdson and BVds
n-type
Nd
p-type
Imagine if we could
create a flat electrical field!
E
Ecrit (30V/um)
Area will about double: diode breakdown will double!
On state resistance  Length x specific resistance
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Henk Boezen, SOI Workshop July 2015
Impact of epi thickness on lateral diode
Ecrit
+HV
p+
n+
n-
Thick-epi diode
BV = 370V
p+HV
p+
Ecrit
Optimal
Resurf Diode
BV = 1150V
RESURF: Reduced SURface Field effect.
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Henk Boezen, SOI Workshop July 2015
+HV
p+
Ecrit
pField engineering with Resurf effect:
Reduction of peaks in the electrical field with the help of
- a nearby junction,
- a fieldplate,
- the dope profile.
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Henk Boezen, SOI Workshop July 2015
Schematic cross section of a n-Ldmos in ABCD.
Source
Gate
Drain
LOCOS
BOX
Handle wafer / Substrate
SOI enables smaller Power transistors.
COMPANY CONFIDENTIAL 15
Henk Boezen, SOI Workshop July 2015
Simulated potential distribution of a n-Ldmos.
0V
Double RESURF’ effect due to bottom and top field plates,
- allows higher doping drift region.
- results in a lower Ron , thus smaller device area.
COMPANY CONFIDENTIAL 16
Henk Boezen, SOI Workshop July 2015
Various bias conditions are relatively easy to
handle on SOI.
P.e.: p-type Ldmos at high side:
Source
60V
Gate
55V
Drain
LOCOS
BOX
Handle wafer / Substrate
At high side: accumulation in the drift region:
Lower Rdson, and higher Isat
0V
COMPANY CONFIDENTIAL 17
Henk Boezen, SOI Workshop July 2015
Thermal isolation of buried oxide a problem?
Thermal conductivity:
– Silicon:
– Silicon oxide:
1.5
0.014
W/K.cm
W/K.cm
The substrate thickness is typical 350 um, and the buried oxide 1um.
Very short heat pulses will not reach the Buried oxide.
Stationary heating: buried oxide acts as 100um silicon
But heat pulses in range of 10us are more difficult to handle.
ESD pulse duration < 1 µs  self heating comparable to bulk Si
COMPANY CONFIDENTIAL 18
Henk Boezen, SOI Workshop July 2015
Pro’s and con’s of SOI for power devices
Small HV devices.
Small lateral isolation (oxide).
Possibility to allow below ground or above supply voltages, which is very difficult
on bulk. This results in increased robustness of HV devices.
Possibility to design isolated low voltage circuits in own substrate
Low junction leakage.
Fast reverse recovery behavior.
Lower Rdson increase over temperature (compared to bulk)
Possibility for flexible ESD protection network characteristics
Thermal behavior is not as good as bulk. Sofar not an issue at NXP.
Price of starting material is high.
COMPANY CONFIDENTIAL 19
Henk Boezen, SOI Workshop July 2015
SOI for Smart Power devices.
Introduction Smart power technology
Power devices in SOI
ESD on SOI
Applications with SOI based power devices
Trends and future of SOI in Smart Power.
COMPANY CONFIDENTIAL 20
Henk Boezen, SOI Workshop July 2015
ESD devices: SOI versus Bulk
The silicon is confined on SOI
 Current flow is confined
 Ron is expected to be higher and It2 lower when compared to bulk
Diode:
– small A-A spacing, current not very deep  almost no impact
Snapback device:
– noticeable impact, depending on length of device
– LVTSCR: probably most impacted, due to C-A spacing
– But this device is not used because of low holding voltage
Active clamp:
– limited impact  covered by model  dimensioning by Spice simulation
Reverse diode of most devices:
– relatively large A-A spacing  not optimal  add explicit diode
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Henk Boezen, SOI Workshop July 2015
LVTSCR bulk vs. Si
SCR typically has deep current flow  restricted in SOI  lower It2
35.0
30.0
SOI
Bulk
J_TLP (mA/µm)
25.0
20.0
15.0
10.0
5.0
0.0
0
2
4
6
8
10
V_TLP (V)
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Henk Boezen, SOI Workshop July 2015
Advantages
In SOI it is easy to stack devices without creating additional parasitic
devices
This offers the possibility to build HV protections with LV devices
Note that typically HV devices are not ESD robust
– Deep snapback
– Slow due to large internal distances
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Henk Boezen, SOI Workshop July 2015
Diodes
Single diode
Stack of 4 identical diodes  higher Von and Ron, same It2
18
Increase size to
reduce Ron and
increase It2
Single Diode
Stack of 4 Diodes
Stack of 4 Large Diodes
16
14
I_TLP (A)
12
10
8
6
4
2
0
0
5
10
15
20
V_TLP (V)
COMPANY CONFIDENTIAL 24
Henk Boezen, SOI Workshop July 2015
Diode in reverse
Diode stack needed to obtain required reverse breakdown value
1.8
1.6
1.4
I_TLP (A)
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0
10
20
30
40
50
60
70
V_TLP (V)
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Henk Boezen, SOI Workshop July 2015
PNPs
Small snapback due to use of PNP
Stack can be used to obtain higher Vt1 and Vh
– E.g. 7 PNPs for Vh ~70 V
1.4
Perfect scaling:
J versus Voltage/device
Single PNP
1.2
Stack of 7 PNPs
J_TLP (mA/µm)
1
0.8
0.6
0.4
0.2
0
0
2
4
6
8
10
12
14
V_TLP (V)
COMPANY CONFIDENTIAL 26
Henk Boezen, SOI Workshop July 2015
HV protection
HV protection built with LV devices, e.g. for CAN bus
Rail based system with PNP’s and diodes
10.0
Ron ~1 Ω
9.0
It2 >> 10 A
8.0
I_TLP (A)
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
0
20
40
60
80
100
V_TLP (V)
COMPANY CONFIDENTIAL 27
Henk Boezen, SOI Workshop July 2015
SOI for Smart Power devices.
Introduction Smart power technology
Power devices in SOI
ESD on SOI
Applications with SOI based power devices
Trends and future of SOI in Smart Power.
COMPANY CONFIDENTIAL 28
Henk Boezen, SOI Workshop July 2015
Automotive Networking Solutions
Integration
CAN
incl. Supply,
Watchdog,
and IO functions
COMPANY CONFIDENTIAL 29
Henk Boezen, SOI Workshop July 2015
What does the transceiver?
Micro
controller
Tranceiver
Rx
sensor
actuator
Tx
Micro
controller
Bus
Tx
Tranceiver
Rx
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Henk Boezen, SOI Workshop July 2015
Bus as antenna…
Signals on the Bus should not radiate
– CAN uses twisted wire
– LIN uses 1 wire with “sloped” signal
5V or 14V signals from the Bus will be contaminated with noise (up to
100V!)
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Henk Boezen, SOI Workshop July 2015
CAN output stages
Vcc
Vcc
Easy in
SOI !
Floating
Driver
Circuit
5V
Driver
Circuit
PCA82C251 (bulk)
TJA1041 (SOI)
COMPANY CONFIDENTIAL 32
Henk Boezen, SOI Workshop July 2015
SOI ABCD for transceivers
Enable robust product solutions
– Robust against bias against below ground / above supply
– Latch up can be fully avoided.
Enable improved EMC due fully isolated devices.
– Allows symmetric design of output stage.
– Less cross talk due to buried oxide.
dBuV
100
90
Industry Standard
80
Ease of design
70
SOI technology
60
50
40
30
20
10
0
0
2
4
6
8
10
12
14
16
18
20
MHz
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Henk Boezen, SOI Workshop July 2015
Typical Solid State Lighting Architecture
LEDs require flexible, integrated & networked drive electronics
Old bulb solution
required a power switch
DRIVER
DRIVER
DRIVER
DRIVER
DRIVER
BCM
DRIVER
Body
Control
Module
DRIVER
DRIVER
BCM
DRIVER
PWM
FET
Diagnostic
Battery
CENTRAL
PROCESSING
UNIT
R = “coding” resistor
Specifying LED BIN
DRIVER
Sensors /
Control
BCM
Lighting Control Module
DRIVER
DRIVER
Diode
…
Vbat
FET
LED
Driver
IC
GND
EMC
filtering
R
EMC
filtering
PWM
Body
Control
Module
Short
circuit
protection
……
Coil
……
DRIVER
…
DRIVER
Vbatt
GND
PWM
Battery
NTC
MCU
Voltage
regulation
R-Coding
Signal
conditioning
NTC/PTC
All LED Control Modules need this system functionality.
Module flexibility is crucial, since current designs still very customer specific.
Driver Integration - Smaller footprint, improved system reliability & Lower system cost
Expect networking of the Lighting Control Module as penetration of LEDs increases.
COMPANY CONFIDENTIAL 34
Henk Boezen, SOI Workshop July 2015
NXP Multi Channel Automotive LED drivers
THE most cost effective architecture for multi-channel LED platform
Key Advantages of Architecture
Flexibility – with a common architecture
LED Driver Module
Drive all LED string configurations & matrix or segment switching
SPI Interface for configurability, control & diagnostics
Scalability – with a common architecture
Power
Drive 2 – 12+ LED channels and 30 to 140W output power
ASLx500
Multi-phase
Boost IC
ASLx415
Multi channel
Buck IC
Micro
ASLx415
Multi channel
Buck IC
Footprint compatibility
2-12+ Channels in small packages
Multi-phase boost stage
Lower ripple on battery line by adjusting the output phases
Lower system cost by optimizing size of boost stage
Comm
2 output voltages from boost stage (up to 70V)
Optimizes system efficiency by matching output voltage to load
Drive >1.5A LED current per channel
Full automotive AEC Q100
External FETs
In mass production
Better thermal & power design, EMC optimization
>87% system efficiency
COMPANY CONFIDENTIAL 35
Henk Boezen, SOI Workshop July 2015
ASL2415SHN/3415SHN – Buck Converter
Multi-Channel Buck Mode LED drivers with integrated SPI
ASL2415SHN is a 2 channel buck mode
LED driver IC.
ASL2415SHN
ASL3415SHN is a 3 channel buck mode LED
driver IC.
ASL3415SHN
A highly integrated multi channel programmable hysteretic constant current buck converter
–
Wide operating input voltage range 10V..80V & LED voltage range 2.5V – 70V
5V SPI interface for control & diagnostic communication with external micro.
–
Programmable LED current from 120mA to larger than 1.5A with 5% accuracy
PWM dimming from 0 or 1.5 to 100%, 0.1% resolution
LED open and short-to-ground fault detection.
COMPANY CONFIDENTIAL 36
Henk Boezen, SOI Workshop July 2015
Multi Channel LED Driver ASL3415
Low voltage blocks in local
substrate
Design Advantage of SOI
COMPANY CONFIDENTIAL 37
Henk Boezen, SOI Workshop July 2015
SOI for Smart Power devices.
Introduction Smart power technology
Power devices in SOI
ESD on SOI
Applications with SOI based power devices
Trends and future of SOI in Smart Power.
COMPANY CONFIDENTIAL 38
Henk Boezen, SOI Workshop July 2015
Trends and future of SOI in Smart Power
Applications:
Existing applications ask for more efficiency and digital content:
–
–
–
–
Automotive:
Power conversion
Audio:
Lighting
quality, reliability, costs, functionality.
costs, efficiency
costs, power consumption.
costs, energy efficiency.
New applications are developing very fast:
– Electrical Vehicles: power invertors, motor control, battery management.
– Solar: Photo Voltaic cells, controls and battery management
– LED: drivers and smart drivers.
COMPANY CONFIDENTIAL 39
Henk Boezen, SOI Workshop July 2015
Trends and future of SOI in Smart Power
Technology:
Digital density is increasing
– IDM’s move from 0.6 and 0.35 now to 0.18 and 0.14.
SOI is used for options.
– Foundries offer embedded up to 35V on bulk in 0.18um.
New materials enter: SiC and GaN.
COMPANY CONFIDENTIAL 40
Henk Boezen, SOI Workshop July 2015
NXP’s answer: A-BCD9
A-BCD9 enables monolithic integration of micro + transceiver.
EHN nmos transistor
Vgate = 0, 1.65V and 3.3V
300
Jds [mA/mm]
250
200
150
100
50
0
0
50
100
150
200
Vds [V]
COMPANY CONFIDENTIAL 41
Henk Boezen, SOI Workshop July 2015
Summary
SOI gives a clear performance advantage in Smart Power
Technologies.
SOI has clear design advantages over bulk technologies
SOI is running in volume production for many years.
COMPANY CONFIDENTIAL 42
Henk Boezen, SOI Workshop July 2015
Thank you