RADIATION EFFECTS IN SEMICONDUCTOR MATERIALS AND DEVICES FOR SPACE APPLICATIONS Cor Claeys and Eddy Simoen IMEC 2010
OUTLINE Introduction Total Dose Effects in thin gate oxides RILC, RSB, SEGR, Latent Damage Microdose Effects Device Scaling Bulk & SOI FinFETs Ge devices Conclusions IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 2
INTRODUCTION COTS important for Space Applications Advanced CMOS Technologies Reduced Gate Dielectrics Alternative Substrates: SOI, ssoi, Ge, sge, GOI... Advanced Process Modules: High-κ Dielectrics, Strain Engineering, Alternative Device Concepts Double gate, FinFETs, GAA, Nanowires, Impact on Radiation Hardening? IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 3
INTRODUCTION Ionizing Damage: creation of electron-hole pairs across the band gap Linear Energy Transfer (LET) function (in MeV cm 2 /g) 1 rad=100 erg/g=6.24x10 13 ev/g - 1 Gray=1 J/kg=100 rad Displacement Damage: creation of vacancyinterstitial (V-I) pairs by displacement of a lattice atom Non Ionizing Energy Loss (NIEL) function IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 4
IONIZING AND DISPLACEMENT DAMAGE = F(PARTICLE, ENERGY) The energy loss rate through ionization and excitation of the Si lattice (LET) and through atomic displacements (NIEL) versus proton energy. Only a fraction of 1% of the energy loss goes into displacement processes IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 5
IONIZING DAMAGE IN MOS Gate: carries away the charge Oxide gate ++ n-si --+ p-type silicon Silicon: electron-hole pairs can recombine in the neutral bulk In case of a p-n junction, the electric field separates electrons and holes. This leads to a transient charging phenomenon Single Event Upsets (SEU) Permanent ionizing damage only in the dielectric layers: gate oxide, isolation or field oxide and buried oxide (SOI) IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 6
STANDARD TOTAL DOSE RADIATION EFFECTS N ot & N it IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 7
GATE OXIDE SCALING Gate current before (full lines) and after (dashed lines) a 67 MeV 2.9x10 12 p/cm 2 proton irradiation for a 0.09 µm n- and 0.08 µm p-mosfet with 2.0 nm oxide. Gate Current (A) 10-9 10-10 10-11 10-12 L=0.09 µm n-mos; L=0.08 µm p-mos V =-0.025 V DS floating V =0.025 V DS p-mos n-mos n-mos p-mos 10-13 t ox =2 nm -1.5-1 -0.5 0 0.5 1 1.5 Gate Voltage (V) IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 8
DEVICE SCALING V t ~ t ox 2 Good TID resistance of the Gate oxide Radiation effects will be caused by parasitic conduction related to Shallow Trench Isolation oxide: Bulk Buried oxide for SOI devices Occurrence of other radiation related phenomena IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 9
IONIZING DAMAGE: THIN GATE OXIDES Uniform gate current flow Breakdown path Trap-assisted RILC RILC by radiation-induced Neutral electron traps IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 10
IMPACT OF HIGH-ENERGY IONS ON GATE OXIDE Radiation-Induced Leakage Current (RILC) Radiation-Induced Soft Breakdown (RSB) Increase of off-state power consumption but no real concern IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 11
ION-INDUCED DEGRADATION OF GATE DIELECTRICS A. Cester, L. Bandiera, M. Ceschia, G. Ghidini and A. Paccagnella, IEEE Trans. Nucl. Sci., 48, pp. 2093-2100 (2001) IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 12
SINGLE EVENT GATE RUPTURE L.W. Massengill, B.K. Choi, D.M. Fleetwood, R.D. Schrimpf, M.R. Shaneyfelt, T.L. Meisenheimer, P.E. Dodd, J.R. Schwank, Y.M. Lee, R.S. Johnson and G. Lucovsky, IEEE Trans. Nucl. Sci., 48, pp. 1904-1912 (2001) SEGR * Operating voltage lower than critical value * Critical LET threshold IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 13
LATENT RADIATION DAMAGE IN THIN GATE OXIDES 1 J.S. Suehle, E.M. Vogel, P. Roitman, J.F. Conley Jr., J.B. Bernstein and C.E. Weintraub, Appl. Phys. Lett., 80, pp. 1282-1284 (2002) 129 Xe Irradiation, t ox = 3.0 nm, V stress = - 4.9 V * No parameter shift after irradiation only * Reduced oxide lifetime after accelerated testing ln(ln(1/(1-f))) 0-1 -2-3 1 10 100 1000 10000 Pre-irradiation 1 x 10 5 ions/cm 2 1 x 10 6 ions/cm 2 1 x 10 7 ions/cm 2 LET > 30 MeV/cm 2 Time-to-Breakdown (s) Weibull lifetime distribution of MOS capacitors subjected to constant voltage stress at V stress =-4.9 V before and after heavy ion irradiation IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 14
LATENT RADIATION DAMAGE IN THIN GATE OXIDES J.S. Suehle, E.M. Vogel, P. Roitman, J.F. Conley Jr., J.B. Bernstein and C.E. Weintraub, Appl. Phys. Lett., 80, pp. 1282-1284 (2002) Weibull lifetime distribution of MOS capacitors subjected to constant voltage stress at V stress =-5.0 V before and after 60 Co irradiation. IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 15
LATENT RADIATION DAMAGE - ION FLUENCE EFFECT A. Cester, S. Cimino, E. Miranda, A. Candelori, G. Ghidini and A. Paccagnella, IEEE Trans. Nucl. Sci., 50, pp. 2167 2175 (2003) Gate current during CVS at V CVS = 4.2 V on three samples with gate area 10-2 cm 2 irradiated with 256-MeV I ions at different fluences Excess gate current Density (J e ) normalized to the ion fluence (φ) measured during CVS at V CVS =4.2 V IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 16
LATENT RADIATION DAMAGE STRESSING VOLTAGE A. Cester, S. Cimino, E. Miranda, A. Candelori, G. Ghidini and A. Paccagnella, IEEE Trans. Nucl. Sci., 50, pp. 2167-2175 (2003) < I(t s )>= I N [1-exp(-λt s )] Gate current derivative di g /dt of the gate current, equivalent to the density of spots, with respect to the stressing time during CVS. The derivative has been evaluated as the slope of the initial part of the gate current evolution (t stress < 1000 s), i.e., where the gate current increases almost linearly IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 17
100 NM PD SOI TECHNOLOGY 10-20% CHANGE F(ION FLUENCE) STAIRCASE VOLTAGE STRESS A. Cester, S. Gerardin, A. Paccagnella, E. Simoen and C. Claeys, IEEE Trans. Nucl. Sci., 52, pp. 2252-2258 (2005) Gate current measured at V g = V g,stress during FN injection of devices processed in an 0.1 µm PD SOI technology. V g,stress starts from 2.5 V and increases up to 4 V with 50-mV step every 100 s. The stress was performed on fresh and irradiated devices with two different ion fluences (2.5 and 0.5 I ions/µm 2 ). IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 18
65 NM FD SOI TECHNOLOGY NO CHANGE. A. Griffoni, S. Gerardin, A. Cester, A. Paccagnella, E. Simoen and C. Claeys, IEEE Trans. Nucl. Sci., 54, pp. 2257-2263 (2007) Gate current time to breakdown for irradiated (2.5 I ions/µm 2 ) and unirradiated FD SOI MOSFETs (W=L = 10 µm/10 µm) fabricated in a 65 nm technology with different strain levels. The devices were stressed with a staircase voltage from 2 V to 4 V with 50-mV steps, each lasting 100 s. IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 19
HEAVY ION STRIKES: MICRODOSE EFFECTS S. Gerardin, M. Bagatin, A. Cester, A. Paccagnella and B. Kaczer, IEEE Trans. Nucl. Sci., 53, pp. 3675-3680 (2006) charge build-up in the STI charge build-up in the LDD region Statistical in nature Defect generation in the oxide IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 20
TRANSISTOR SCALING New process modules New materials New device concepts metal gate FinFET graphene nanowires Ge/IIIV 16 and beyond silicide >=130 USJ strain 90-65-45 NiSi NiSi FUSI Strain, USJ 25 nm HfO 2 high -k time 45-32 High-k, Metal Gate 32-22-16 Non-planar devices Front End IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 21
BULK AND SOI FINFETS S. Put, E. Simoen, M. Jurczak, M. Van Uffelen, P. Leroux and C. Claeys, IEEE EDL, 31, pp. 243-245, 2010 a b I d and g m as a function of V g for a SOI (a) and a bulk p-mugfet (b). Both devices have a single fin and a fin width of 885 nm. (L=165 nm, V d =-50mV). 60 Co irradiation of 10 hours at a dose rate of 1 kgy/hr. IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 22
HIGH MOBILITY SUBSTRATES Ge DEVICES R. Arora, E. Simoen, E.X. Zhang, D.M. Fleetwood, R.D. Schrimpf, K.F. Galloway, B.K. Choi,J. Mitard, M. Meuris, C. Claeys, A. Madan, J. D. Cressler, RADECS 2009 (IEEE T-NS) 8 ML SI 5 ML SI IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 23
CONCLUSIONS Deep submicron CMOS technologies are radiation hard for total dose effects STI or BOX must be optimized RILC, RSB, SEGR and Latent Damage For thin gate oxides heavy ion strikes are important Microdose effects have to be taken into account requiring a statistical analysis of a technology New process modules, new materials and alternative device concepts have to be investigated IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 24
ACKNOWLEDGMENT The authors want to acknowledge A. Griffoni, D. Fleetwood, K. Galloway, S. Gerardin, G. Meneghesso, A. Paccagnella and S. Put for the use of co-authored results. Part of the work was done under ESA contract 22485/09/NL/PA. The imec Process Technology Unit is acknowledged for the device fabrication IMEC 2010 IEEE EDS Colloquia, June 7 / C. Claeys 25
IMEC 2010