Feasibility study of a latchup-based particle detector

Transcription

Feasibility study of a
latchup-based particle detector exploiting
commercial CMOS technologies
Alessandro Gabriellia, Giorgio Matteuccia
Giulio Villanib, Marc Weberb
Danilo Demarchic, Pierluigi Civerac
aI.N.F.N.
and Physics Department University of Bologna
Rutherford Appleton Laboratory (RAL), UK
cLaboratorio ChiLab, Engineering Department, Politecnico di Torino
bSTFC
Alessandro Gabrielli IPRD-08 1-4 Oct. 2008
1
Overview
•
•
•
•
Introduction to the Latchup Effect
(4 slides)
State-of-the-art up to 2007
(6 slides)
New proposals: Bologna-RAL-Poli_Turin (9 slides)
Conclusion
2
ENERGY DEPOSITION IN OXIDES
•
Cumulated Ionization: Also called TID: Total Ionizing Dose
Mechanism:
- electron-hole pair creation;
- partial recombination (strong if no electric field);
- electrons: high mobility => leave the oxide;
- holes: very low mobility => mostly trapped
Result:
- net positive charge trapped in the oxide;
- long term trapping at room temperature.
3
ENERGY DEPOSITION IN OXIDES
•
Istantaneous Ionization: Also called SEE: Single Event Effect
Mechanism:
- single highly ionizing particle (incident or secondary ion);
- high e+e- pair density along its track;
- bias across the oxide => transient current across the oxide;
- this mechanism can be helped by the electric field induced in SiO2 by
charges created in Si by the single ionizing particle.
Result:
oxide breakdown
Examples:
- Single Event Upset (SEU);
- Single Event Transient (SET);
- Latchup Effect
4
Thyristor
NPN Base to PNP Collector PNP and viceversa
…….once ignited … it does not turn off spontaneously!!!
The stimulated ignition of latchup effects caused by external radiation
has so far proven to be a hidden hazard for CMOS technologies
Here the latchup effect is proposed as a powerful means of achieving
the precise detection and positioning of a broad range of particles
5
What the “Latchup Effect” is
Basically, it is an ingnition af a
parasitic thyristor-like structure
within a CMOS device and is
ignited by induced charges inside
the silicon whatever their origin.
Traditional CMOS technologies
into radiation environments may be
susceptible and damaged by latchup
6
First study since 2005
If (Vwell is VDD) and
(Vbulk is GND) then ….
It is not a reverse-biased diode plus the
transistor has an internal current gain
7
A Prototype
Commercial components
Q1: PNP BC858C
Q2: NPN 2N3055
“
MJ21194
“
BFY52
“
2N2222A
RN: multiturn variable resistors
8
Spice simulation (Q2=BFY52)
Temperature from 30 to 40oC
700ns
5µA × 2ns = 10fC
Well Current
Out Voltage
Bulk Current
9
Commercial bipolars used
Q2 = 2N2222A BFY52 2N3055
TO-18 metal can
TO-39 metal can
TO-3 metal can
Estimated B-E
charge collection
area
Estimated B-E
charge collection
area
Estimated B-E
charge collection
area
10÷100 µm2
100÷10000 µm2
1 mm2
10
Prototype Construction (Q2=MJ21194)
Metal box with upper sensor
MJ21194 opening
The latchup circuit inside the
box
Transistor Base-Emitter bondings of
the power bjt MJ21194
11
Laboratory test
Estimated sensitivity: ≈1pC
Out signal
NPN
MJ21194
Transistor B-E
1pC-estimated
injected charge
Power-BJT
Same
behaviour but
different
numbers
compared to
simulations
MOST
SENSIBLE
≈ 4µs readout time
12
BJT to MOS transistors
All that has been
investigated via
bipolar transistors
(BJT) can be
obtained using
Metal-Oxide
Semiconductor
(MOS) transistors
13
Here is how to use individual
commercial MOS transistors (74HC04)
NO VDD
NO GND
..with some difficulties, honestly
14
The schematic for many configuration
and tuning capabilities
Drivers
74HC04
Jumpers
15
Again, Spice simulation with MOS…..
Out signal
N-MOS Gate
Input Spike
16
The Test-Board
17
Single Latchup ignition
- Blue line is the N-MOS drain (P-MOS gate)
- Green line is the P-MOS drain (N-MOS gate)
On this line a OverSpike is provided
18
Cyclic Latchup ignition (T=5µs)
RESET – IGNITION OVERSPIKE - RESET – IGNITION OVERSPIKE
Reset
Output
Ignition
OverSpike
- Blue plot is the N-MOS drain (P-MOS gate), “Output” (1V/div)
- Green plot is the P-MOS drain (N-MOS gate)
with the “Ignition OverSpike” (20mV/div)
- Violet plot is a cyclic “Reset” with a 5µs period (1µs/div)
No sooner the ignition OverSpike arrives than the circuit latches
19
Cyclic Latchup ignition (T=5µs)
LEFT PICTURE
- The ignition OverSpike is too weak
- Only a few % of the times the circuit
latches
RIGHT PICTURE
- The ignition OverSpike is high enough
- Most of the times the circuit latches
20
Noise Figure - Summarized S-curve
640µV
Falling S-curve
1
Baseline
+
OverSpike
0
Rising S-curve
10.80
9.68 9.84
11.44
OverSpike Input Voltage (mV)
- A biasing gate baseline of about 950mV was used
- Raising curve has an noise figure estimated in ≈ 640µV, SAY LOWER THAN 1 mV
- The S-curve has an hysteresis
- The estimated sensitivity, by measuring the input impedence, was confirmed to be ≈ 1pC
21
CONCLUSION
Latchup Mechanism can be exploited for:
- particle detection,
- signal amplifier and latch after a sensor’s signal
Using commercial state-of-the-art MOS transistors we have obtained:
- an Error Figure of about 640µV,
- a sensitivity of the order of 1pC, confirmed like for BJTs,
- a readout speed of the order of 1µs.
Latchup Mechanism can be exploited in future applications for :
- high-energy physics,
- radiation monitoring via Floating Gate MOS, (see Villani et al.)
REFERENCES
A. Gabrielli
A. Gabrielli
D. Demarchi, A. Gabrielli
G. Villani, et al.,
“Proposal for solid state particle detector based on latchup effect”, El. Let. 41/11, (2005), 641
“Particle detector prototype based on a discrete-cell sensitive to latchup effect”, Meas. Scie. Tech. 17, (2006), 2269
“Design of an integrated particle detector-cell based on latchup effect”, TWEPP 2007, Prague, CZ, 3-7 Sep. 2007, 445
“Radiation detection and readout based on the latchup effect” PSD08, Glasgow, UK, 1-5 Sep. 2008
22

Feasibility study of a latchup-based particle detector

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