10

Investigation of new chalcogenide materials to improve the PCM robustness L. Perniola

« Robustness » for embedded applications • • • • •

High scalability High endurance Low power consumption High programming speed 10 years data retention at 85°C with GST Intel-STM

B.Gleixner et al. IRPS 2007

Improvement may come from material engineering

SAMSUNG

J.H.Oh et al. IEDM 2006

L. Perniola – Workshop on Innovative Memory Technologies | June, 29, 2011 | 2 © CEA. All rights reserved

Power consumption & endurance

State of the art: doping species GST provides some clues on suitable doping species Carbon doping

Nitrogen doping

Ovonix, EPCOS 2006

S. Ahn & Y.N. Hwang, SAMSUNG, IEDM 2004

H. Horii, SAMSUNG, VLSI 2003


State of the art: GeTe host material

Data Retention

Alternative to GST suitable host material: In-Ge-Te

Ge4Sb1Te5+ SiOx

T. Morikawa, Hitachi, IEDM 2007

L. Perniola – Workshop on Innovative Memory Technologies | June, 29, 2011 | 4

W. Czubatyj, Ovonyx,©EDL 2010 CEA. All rights reserved

State of the art: GeTe host material

Optical domain

Philips: (Coombs & al., APL 1995) Ge0.4Te0.6 & Ge0.6Te0.4 are slower strongly growth-controlled PC (ie ~200500 ns) Behavior not due to material segregation but due to different chemical properties

IBM-Macronix (S. Raoux, APL 2009) Crystallization process GexTey all growth-controlled


Aim of the work: doped GeTe PCM Strong variation of RESET current in GST-C and GST-N Enhancement of data retention perfs in Ge4Sb1Te5+ SiOx and In-GeTe large speed variation fct of GexTey (optical domain)

Accurate analysis of C and N doping impact in GeTe


GeTeC: Optical reflectivity & electrical resistivity

TC GeTe

~180°C

GeTeC4%

~300°C

GeTeC10%

~370°C

Strong enhangement of Tc Slower transition for higher C-doping G. Betti Beneventi, IMW 2010 L. Perniola – Workshop on Innovative Memory Technologies | June, 29, 2011 | 7 © CEA. All rights reserved

GeTeC: RESET current reduction 30 nm-thick GeTeC integrated in PCM

GeTeC4%: IRESET -10% wrt GST GeTeC10%: IRESET -30% wrt GST G. Betti Beneventi, IMW 2010 L. Perniola – Workshop on Innovative Memory Technologies | June, 29, 2011 | 8 © CEA. All rights reserved

GeTeC: R-V programming characteristics* GeTe

• Raising C content

GeTeC4%

GeTeC10%

Slow down of SET speed Reduction of VRESET

* Each test is an average on ~10 cells

G. Betti Beneventi, ESSDERC 2010


GeTeC: Data retention @ fixed T & extrapolation*

Fail temperature @ 10 y GeTeC10%

~127°C

* Each characteristics is the median of a population of > 30 cells G. Betti Beneventi, ESSDERC 2010 L. Perniola – Workshop on Innovative Memory Technologies | June, 29, 2011 | 10 © CEA. All rights reserved

A. Fantini, IEDM 2010 L. Perniola – Workshop on Innovative Memory Technologies | June, 29, 2011 | 11 © CEA. All rights reserved

No IRESET reduction

100 nm-thick GeTeN



GexTey: Data Retention 5

10

5

10

Fail time [s]

Resistance [Ω]

6

10

4

10

3

10

2

10 10

1

165°C 170°C 180°C 190°C 200°C 10

54 devices under test

Ge30Te70 2

3

10 10 Time [s]

4

10

5

10

EA

TFAIL(10y)

Ge50Te50

2.2 eV

95 °C

Ge40Te60

3.1 eV

117 °C

Ge30Te70

3.6 eV

126 °C

4

10

Ge30Te70 Ge40Te60 Ge50Te50

3

10

2

10

10

24.5 25

25.5 26 26.5 27 1/(KBT) [eV-1]

Raising Te at. %: Enhanced stability of RESET-state G. Navarro, IMW 2011 N. Pashkov, to be presented @ ESSDERC 2011


Conclusion GeTe host material features robustness for embedded applications in terms of: RESET current reduction: GeTeC10% up to ~30% Ge30Te70 up to ~25% RESET current reduction comes at a tradeoff on programming time (SET operation) ~1 decade longer Data retention: 100 nm-thick GeTeN2% TFAIL @ 10 yrs~154°C 100 nm-thick Ge30Te70 TFAIL @ 10 yrs~126°C 30 nm-thick GeTeC10% TFAIL @ 10 yrs~127°C


Acknowledgement V. Sousa, G. Navarro, N. Pashkov, M. Suri, E. Henaff, A. Persico, F. Fillot, F. Pierre, A. Roule, S. Maitrejean, H. Feldis, C. Jahan, J. F. Nodin, A. Toffoli, D. Blachier, A. Bastard, J-C. Bastien, B. Hyot, B. André, G. Reimbold, B. De Salvo, O. Faynot E. Palumbo, P. Zuliani and R. Annunziata of ST-Agrate ePCM LETI-ST project


Merci de votre attention