Electrical modeling of the photoelectric effect induced by a pulsed - - PowerPoint PPT Presentation

Electrical modeling of the photoelectric effect induced by a pulsed laser applied to an SRAM cell.

• A. Sarafianosa,b, C. Roscianb, J.M. Dutertreb, M. Lisarta, A. Triab.

a STMicroelectronics, Avenue Célestin Coq 13790 Rousset, France b Centre de Microélectronique de Provence - Georges Charpak 880 Avenue de Mimet 13541 Gardanne, France

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Outline

Page Introduction 3 Electrical modeling of PN junctions under PLS 5 Presentation of the SRAM cell 7 Theoretical sensitive areas 8 Laser characterization of the SRAM cell 9 Hypothesis 10 SEU sensitivity simulation of the SRAM cell 11 Conclusion 15

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Introduction 1/2

Radiation emitted from the sun is a major threat for electronics devices

Possible simulation: TCAD

Effect of radiation could be tested by: Cyclotron or Pulsed Laser equipment

Electrical simulation

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Introduction 2/2

Characterization and modeling of CMOS devices under laser illumination

Confirm the simplify model

• n CMOS gate:

e.g.: inverter, SRAM cell…

N+/Psub

• A. Sarafianos and al, Building the electrical model of the

pulsed photoelectric laser stimulation of an NMOS transistor in 90nm technology, IRPS 2013.

P+/Nwell Nwell/Psub

• A. Sarafianos and al, Building the electrical model of the

pulsed photoelectric laser stimulation of a PMOS transistor in 90nm technology, IPFA 2013.

+ =

Iph N+ Psub Iph P+ Nwell Iph Nwell Psub V V V

Electrical modeling of photocurrents (Iph) induced in PN junctions

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Sub circuit for each kind of PN junction

Iph N+ Psub Iph P+ Nwell Iph Nwell Psub V V V

Electrical modeling of photocurrents (Iph) induced in PN junctions

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Sub circuit for each kind of PN junction

Dependency of the pulse width Trig signal Takes into account spatial dependency Reverse biased voltage Junction area

Measurement vs electrical simulation for PN junctions under pulsed laser illumination

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N+/Psub P+/Nwell

Good correlation obtain between measurement and electrical simulation permits to build an electrical model of PN junctions under pulsed laser illumination

Presentation of the SRAM cell

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CSRAM 5T Convention: State “0”  DATA_OUT = “0” State “1”  DATA_OUT = “1”

Theoretical sensitive areas

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4 sensitive areas in theory

 2 in state “0”

• Drain of MP1
• Drain of MN2

 And 2 others in state “1”

• Drain of MP2
• Drain of MN1

Laser characterization of the SRAM cell

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Laser equipment features Wavelength 1064 nm Spot size 1 µm Pulse duration 50 ns Laser power 1.7W

Only 3 sensitive areas revealed by measurement

 2 in state “0”

• Drain of MP1
• Drain of MN2

 And 1 others in state “1”

• Drain of MP2

Hypothesis

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Schematic In state 1

4µm 9µm

Hypothesis

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Schematic In state 1

4µm 9µm

Hypothesis

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Schematic In state 1 Large area of the Drain of MN2/MN3 Small area of the Drain of MP2 near

Masking effect

4µm 9µm

Electrical modeling of the SRAM and results

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Electrical simulation result Electrical modeling Comparison with measurement

A B C

Waveforms on point A

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A

Modification of the state of the SRAM from 0 to 1

Waveforms on point B

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Modification of the state of the SRAM from 1 to 0

B

Waveforms on point C

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No state modification

C

Conclusion

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◙ Simulation permits to validate the hypothesis of masking effect. ◙ The validity of our modeling approach is assessed by the good correlation obtained between simulations and measurements. ◙ Perspectives: Simulate new solution more robust against laser injection.

The topology of the cell has an important effect!

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Thank you for your attention… Q & A