A systematic procedure for the development of hardened technology application to the i3t80 hr
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A systematic procedure for the development of hardened technology: application to the I3T80-HR. Karl Grangé – SODERN [email protected] Agenda. Collaboration Initial specifications Initial philosophy: why to harden? The proposed procedure step by step: Technology selection

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A systematic procedure for the development of hardened technology: application to the I3T80-HR

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A systematic procedure for the development of hardened technology application to the i3t80 hr

A systematic procedure for the development of hardened technology:application to the I3T80-HR

Karl Grangé – [email protected]


Agenda

Agenda

  • Collaboration

  • Initial specifications

  • Initial philosophy: why to harden?

  • The proposed procedure step by step:

    • Technology selection

    • Hardening techniques

      • Hardening against TID

      • Hardening against latch-up

    • Design kit development

  • First application: the SPADA_RT ASIC

    • Total dose evaluation

    • Latch-up evaluation

    • Analog SET evaluation

  • Distribution of the I3T80-HR technology

AMICSA’2006 – SODERN


Collaboration

Collaboration

  • This project is an ESA co-funded contract (TOS-EDP):

    • VPC2 project, contract n°18082/04/NL/CB

  • All hardening tasks performed have been done with the support of the CEA (French atomic agency) of Bruyères-Le-Châtel (SEIM)

AMICSA’2006 – SODERN


Initial specifications

Initial specifications

  • Specifications are issued from the VPC2 project:

    • Develop a multi sensor acquisition board, able to be inserted in a SpaceWire/RMAP platform

    • The heart of this acquisition module is a high accuracy / medium speed ASIC called SPADA_RT (Signal Processing ASIC for Detector Array – Radiation Tolerant).

  • Issued from SPADA_RT specifications, hardening task objectives can be summarized as follow:

    • Latch-up threshold:> 80Mev/mg.cm²

    • TID hardness:> 60Krad(Si)

    • Life time:> 10-15 years

  • Considering strong economic pressure, use only commercial CMOS technologies

    • Hardening By Design (none extra cost allowed)

    • European factory

    • MPW / MLM facility for space user (low volume)

AMICSA’2006 – SODERN


Initial philosophy

Initial philosophy

  • Hardening By Design (HBD) seems the ideal approach when dealing with radiations for space use (moderate environment)…

    • Lower cost / higher flexibility compared to dedicated technology

    • State of the art performances

  • … but in practice, comparison with dedicated technology costs is not evident:

    • Time needed to design test vector (including software)

    • Time and set-up costs for testing

    • Time needed to exploit test results.

  • Conclusion: the following approach has been chosen

    • Sub-micron technology + moderate environment = HBD a priori, without test vector.

    • To limit risks, all hardening technique used shall be quantified, even roughly.

AMICSA’2006 – SODERN


Open point 1 why is it necessary to harden

Open point #1: why is it necessary to harden?

  • Decision to harden has been taken following 3 criteria:

    • High reliability with multi-mission specifications

    • Latch-up free

    • Degradation due to total dose

Is it a real issue?

  • Typical dose level for :

    • GEO

    • 4mm of Al

  • Is about ~20Krad(Si)/year, which induces a dose rate of 2Rad(Si)/h.

With a typical 0.35µm technology

Vth [email protected](Si)

Could modern processes be considered radiation tolerant?

1) Low oxide thickness

2) Low dose rate

AMICSA’2006 – SODERN


Open point 2 why is it necessary to consider dose 1

Open point #2: why is it necessary to consider dose (1)?

  • The radiation effect shall not be considered only from the TID point of view:

    • Degradation is time dependent.

    • Degradation is temperature dependent.

    • Degradation is dose rate dependent.

  • Considering only TID at low dose rate will ignore the leakage current failure mode:

    • Low dose rate naturally increases the reliability by about 5 for the same TID

Transistor threshold voltage variation

  • The transistor is less conductor:

    • Timing failure

Low Dose Rate

TID

High Dose Rate

  • The transistor is more conductor:

    • Leakage failure

AMICSA’2006 – SODERN


Open point 2 why is it necessary to consider dose 2

Gate oxide: none relevant degradation up to 100Krad(Si)

Bird beak : Radiation hardness depend of its characteristics

Field oxide: lack of isolation between 3-10Krad(Si)

Open point #2: why is it necessary to consider dose (2)?

  • The conventional NMOS transistor is not hardened against leakage current failure mode:

    • Failure appears in the bird beak zone, side of the transistor itself.

    • The bird beak oxide thickness increases from the gate oxide thickness (7nm) up to field oxide thickness (~500nm): determination of its radiation hardness is very complex.

    • Hardening By Design can address leakage current but not threshold voltage increasing.

AMICSA’2006 – SODERN


Open point 2 why is it necessary to consider dose 3

Open point #2: why is it necessary to consider dose (3)?

  • Conclusion (0.35µm and lower technology considered):

    • Test at low dose rate = only failure related to threshold voltage increasing addressed.

    • Test at high dose rate = both leakage current failure (after radiation) and threshold voltage increasing failure (after annealing) are addressed.

    • To address leakage current failure, it is necessary to harden.

XILINX VIRTEX FPGA vs total dose (0.25µm)

Thermal failure

Failure level

Strongly FPGA code dependent !!!

AMICSA’2006 – SODERN


Open point 2 why is it necessary to consider dose 4

Open point #2: why is it necessary to consider dose (4)?

  • In space environment, some TID sources are issued from discrete events:

    • Passage through the trapped particles belts and polar zones for LEO.

    • Solar flares for GEO and extra planetary missions.

  • It means that the dose rate can be transiently high.

  • x10000

    The solar eruption that took place in August 1972 (> 30Mev)

    Measured solar protons flux (10MeV & 30MeV) between 1965 and 1985 (continuous line = Wolf law)

    AMICSA’2006 – SODERN


    Open point 2 why is it necessary to consider dose 5

    1g/cm² -> 4mm Al

    Open point #2: why is it necessary to consider dose (5)?

    • Practical example: The BEPI-COLOMBO mission

      • Mercury: 0.35UA + very low magnetic field = GEO solar flare x 10.

    • In GEO solar flare environment, the worst case for dose rate is an Anomalous Large (AL) protons solar flare:

      • 5Krad(Si) / 1 day -> 200rad(Si)/h behind 4mm of Al

    • It means that the need for the BEPI-COLOMBO mission considering only large solar protons flares behind 4mm of Al without margins is:

      • 50Krad(Si) for 1 large protons flare with 2Krad(Si)/h of dose rate.

      • 100Krad(Si) for 2 larges protons flares with 2Krad(Si)/h of dose rate…

    • Computation with the software “Space Radiations (v.5.0)” of some protons solar flares:

    • August 1972: 240rad(Si)/h behind 4mm of Al

    • October 1989: 110rad(Si)/h behind 4mm of Al

    AMICSA’2006 – SODERN


    Open point 2 why is it necessary to consider dose 6

    Open point #2: why is it necessary to consider dose (6)?

    • Are large protons flares rare?

    In red: maximum solar cycle

    AMICSA’2006 – SODERN


    Open point 2 why is it necessary to consider dose 7

    Open point #2: why is it necessary to consider dose (7) ?

    • Thus, it is necessary to harden against TID because:

      • It’s bringing reliability margin.

      • All failure modes are addressed.

      • High level of total dose and dose rate tolerance is also minimizing shielding requirement (low mass / volume) and simplify ray tracing consideration.

      • Low level of high dose rate tolerance need a refined mission analysis.

    • Where is the frontier between high and low dose rate?

      • Technology dependent (oxide thickness, quality…)

      • Complex simulations needed

      • Only some certitudes:

        • 10Krad(Si)/h -> high dose rate

        • 100Rad(Si)/h -> low dose rate

    AMICSA’2006 – SODERN


    Open point 2 why is it necessary to consider dose 8

    Open point #2: why is it necessary to consider dose (8) ?

    • How to apply standards?

      • Low dose rate windows:

        • Earth missions

        • Worst case for bipolar transistors

          • ECSS 22900: 36-360rad(Si)/h

          • MIL.STD.883F method 1019.6: < 0.1rad(Si)/s

      • High dose rate

        • Extra-planetary mission

        • Worst case for MOS transistors:

          • ECSS 22900: 3-30Krad(Si)/h

          • MIL.STD.883F method 1019.6: 50-300rad(Si)/s

    AMICSA’2006 – SODERN


    Hardening procedure general guidelines

    Hardening procedure: general guidelines

    • Used approach

      • Use a systematic approach:

        • Prevent any marginal cases

        • Reaction against technology disappearance

        • None local optimization, taking into account biasing current, function…

      • Use all known hardening measures, with a « light » approach:

        • None test vector

        • None new techniques

    • Risk management about the light approach

      • Limit the temperature range (latch-up).

      • None memory point (SEU).

      • None bipolar structure.

      • Choice of the technology is part of the hardening procedure

      • « Light » environmental specifications (60KRad / 80MeV/mg.cm²)

    AMICSA’2006 – SODERN


    Technology selection criterion 1

    Technology selection criterion (1)

    • Economic consideration

      • Exclusive supplier of a « big » customer

      • Market (HV, OPTO, OTP… options)

      • Second source, introduction year

      • Distribution (MPW ? Number of run per year ?)

    • Electrical performances

      • Simulate some representative cases

      • Identify and quantify critical parameters (channel length, current density…)

      • Specific needs (analog capacitors…)

    • Intrinsic radiation level estimation

      • Intrinsic total dose level estimation:

        • Gate oxide thickness, voltage threshold, kind of isolation...

      • Intrinsic latch-up level estimation

        • EPI characteristic, isolation, Twin Tub, temperature range, diffusion depth, retrograde wells…

      • Technological characteristics allowing usual efficient countermeasures:

        • Buried layer, Shottky module, number of metal tracks

    AMICSA’2006 – SODERN


    Technology selection criterion 2

    Technology selection criterion (2)

    • Subjective approach shall be avoided (the smallest, the fashion technology…)

      • Ex: XFAB 1µm  certainly the best choice for latch-up, life time and reliability but incompatible with the electrical need.

    • Point attribution procedure concerning 21 criterion in the previous 3 categories has been established:

      • Elimination:incompatibility with the application.

      • Negative point:hypothesis done in the initial analysis were optimistic on this point.

      • Null:conform to the initial analysis

      • Positive point:Real advantage compared to the initial analysis.

        for each criteria, an “ideal” response shall be prepared.

    AMICSA’2006 – SODERN


    Technology selection criterion 3

    Technology selection criterion (3)

    Issued from economic analysis on life time

    Issued from economic analysis of project costs.

    Issued from initial analysis + simulations

    Extensive bibliography of well known hardening techniques

    Customer request

    Red = parameters with elimination condition

    AMICSA’2006 – SODERN


    Technology selection criterion 4

    Technology selection criterion (4)

    • This systematic procedure help to formalize the need.

    • All proposed parameters are accessible with a simple NDA.

    • The selected technology is the I3T80 CMOS 0.35µm from AMIS (ex ALCATEL).

      • The I3T80 is a hetero epitaxy process, which allow HV devices thanks to electrically isolated pocket

      • This kind of process is growing due to SoC applications.

    N-epitaxy

    NEPI

    NEPI

    Deep P-plugs allow electrical isolation

    (80V) of adjacent N-EPI pockets

    P-substrate

    AMICSA’2006 – SODERN


    Hardening technique tid 1

    Hardening technique: TID (1)

    • The following failure modes are addressed:

      • Device to device leakage current (NMOS):

      • Intra device leakage current (NMOS)

    AMICSA’2006 – SODERN


    Hardening technique tid 2

    Hardening technique: TID (2)

    • NMOS device to device leakage current is easily cancelled via systematic guard rings

    AMICSA’2006 – SODERN


    Hardening technique tid 3

    Hardening technique: TID (3)

    • For the intra device leakage current, a modified NMOS geometry is needed:

      • Classical circular geometry is not adopted because accurate electrical model can not be obtained without tests.

    • The geometry chosen is electrically 80% compatible with the classical geometry and its hardening level is compliant with 100Krad(Si).

    AMICSA’2006 – SODERN


    Hardening technique tid 4

    Hardening technique: TID (4)

    Geometry

    Electrical model

    Thanks to its great similitude with the classical geometry, an high accuracy is obtained on the electrical modeling “a priori”.

    AMICSA’2006 – SODERN


    Hardening technique latch up 1

    Hardening technique: Latch-up (1)

    • As baseline, the proposed technology increases the latch-up hardening by a factor 6 if NMOS and PMOS transistors are manufactured in separated pockets.

    Parasitic SCR circuit

    AMICSA’2006 – SODERN


    Hardening technique latch up 2

    Hardening technique: Latch-up (2)

    • In addition to the previous rule (NMOS & PMOS shall be manufactured in separated EPI pocket), others hardening rules are added (see initial philosophy):

      • Systematic guard ring around PMOS and NMOS

      • PMOS and NMOS above buried layer

      • Limit the transistor size

      • Limit the wells (buried layer) size

    • Purpose of size limiting rules is to prevent:

      • S/D junction turn ON for transistor sizing limitation

      • Wells junction turn ON for NWELL or PWELL sizing limitation

        In case of ion strike.

    • Sizing limitation is computed with analytical models.

    AMICSA’2006 – SODERN


    Hardening technique latch up 3

    Hardening technique: Latch-up (3)

    • Cross-section with hardening rules:

      • NMOS and PMOS in separated N-EPI pocket

      • NMOS and PMOS wells above buried layer

      • NMOS and PMOS have maximum dimension

      • NMOS and PMOS wells have maximum dimension

    AMICSA’2006 – SODERN


    Hardening technique latch up 4

    Hardening technique: Latch-up (4)

    • Sub-model 1: Layer isolated by junction is used to fix the maximum transistor size.

    • Sub-model 2: layer above a low impedance buried layer with the same polarity (N or P) used to fix the maximum wells dimension:

    2.R1max

    S/D diffusion

    POLY gate

    Guard ring

    Sub-model1: Transistor size

    Charges (ion)

    Buried layer

    NPLUG

    NEPI

    2.R2max

    Wells (N or P)

    Sub-model1: Wells size

    AMICSA’2006 – SODERN


    Practical implementation of hardening rules

    Practical implementation of hardening rules

    • Practically and to prevent weak points, a new design kit has been coded with all hardening rules (ESD pads included)

    • Compared to the original one, the following modifications have been done:

      • Unused elements removed (front and back end)

      • MOS electrical models modified

      • MOS geometries modified

      • DRC rules modified (latch-up rules + detection of removed elements)

      • Extraction rules modified (mainly for NMOS extraction)

      • Basic library modified (ESD pads)

      • Digital gates redesigned

    • 17 months have been necessary for:

      • Technology selection

      • Hardening rules

      • Design kit coding

      • SPADA_RT chip design and test

    AMICSA’2006 – SODERN


    First application the spada rt

    First application: the SPADA_RT

    • The proposed flow have been validated with the development of an mixed ASIC.

      • SPADA_RT = Signal Processing ASIC for Detector Array _ Radiation Tolerant.

      • Multi sensor chip: CCD, APS, HgCdTe

      • Include all necessary circuitry for sensor / house keeping conditioning (ADC excluded)

    • Both electrical and environmental specifications have been met at the first run.

    AMICSA’2006 – SODERN


    Spada rt tid results 1

    SPADA_RT TID results (1)

    • TID evaluation of the SPADA_RT has been done at PAGURE (France) facility.

    • Method used is the ESCC.22900 method:

      • Standard windows

      • 10Krad(Si)/h

      • 5 steps: 0Krad(Si), 30Krad(Si), 60Krad(Si), 120Krad(Si) and annealing.

    • 5 dies

    • None functional or specification failure has been measured.

    AMICSA’2006 – SODERN


    Spada rt tid results 2

    SPADA_RT TID results (2)

    AMICSA’2006 – SODERN


    Spada rt latch up results

    Specie

    Angle

    Flux (p/(cm².s))

    LET (Si)

    Penetration (µm)

    C

    1E7

    1.2 Mev/mg.cm²

    266

    Ne

    1E7

    3.3 Mev/mg.cm²

    199

    Ar

    1E7

    10.1 Mev/mg.cm²

    120

    Ni

    1E7

    21.9 Mev/mg.cm²

    85

    Kr

    1E7

    32.4 Mev/mg.cm²

    92

    Kr

    60°

    1E7

    64.8 Mev/mg.cm²

    46

    SPADA_RT latch-up results

    • Test set-up:

      • Power supplies:+3.3V +/-2%

      • Number of DUT:5

      • Temperature:+25°C +/- 2°C

      • Die pixel frequency:120KHz

      • Location:LOUVAIN (CYCLONE)

      • Heavy ions cocktail:See the next table.

    • None latch-up detected.

    AMICSA’2006 – SODERN


    Spada rt analog set results

    SPADA_RT analog SET results

    • A complete characterization of analog Single Effect Transient (Analog SET) have been done:

      • Event = upset of +/-25mV around the steady state value (better accuracy is not possible due to the noisy environment)

    AMICSA’2006 – SODERN


    I3t80 hr distribution 1

    I3T80-HR distribution (1)

    • In accordance with ESA, this technology is now available for all potential ESA users:

      • MPW facilities always accessible

      • SODERN / EUROPRACTICE kit distribution (under analysis)

    • The nominal kit is available under HyperSilicon software suite (TANNER)

      • Low cost

      • New verification suite include is compatible with CALIBRE

      • Digital & analog library accessible (including the SPADA_RT)

    • In addition of this nominal kit, an innovative distribution flow called Netlist-to-layout is also accessible:

      • From our library, the user develops the front end, SODERN make the back end, up to the tape out,

      • User do not need any specific software or competences: he simply uses a low cost simulator (PSPICE, HSPICE…).

      • Similar digital flow in 2007.

    AMICSA’2006 – SODERN


    I3t80 hr distribution 2

    I3T80-HR distribution (2)

    AMICSA’2006 – SODERN


    A systematic procedure for the development of hardened technology application to the i3t80 hr

    End

    • Thank you for your attention.

    Karl Grangé – [email protected]

    AMICSA’2006 – SODERN


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