(Non-volatile)MRAM FRAM (Phase Change) (Chalcogenide)(Non-volatile) (Memory) (Crystalline State) (Amorphous State) (Resistance) 130 C 1960ECDS. R. Ovshinsky (Chalcogenide) (Switching) (Memory) Ovonic Switch (As-deposited) 14 71
10 6 01 CD DVD (IC) VIA (O)(S)(Se) (Te)(Po) (Phonon) 1970 (Te-based Alloys)80 Te 81 Ge 15 Sb 2 S 2 Ge-Te Ge 15 Te 85 Sb S 1. (Melt-quench) (Vitrified) 2. Ge-Sb-Te In-Ag-Sb-Te Ge- Sb-TeMatsushita 1995 650MBPD (Powerful Optical Disk System) PD 100 Ge-Sb-Te (2.6 GB/side) DVD- Binary Ternary Quaternary GaSb Ge 2 Sb 2 Te 5 AgInSbTe InSb InSbTe (Ge, Sn)SbTe InSe GaSeTe GeSb (SeTe) Sb 2 Te 3 SnSbTe 4 Te 81 Ge 15 Sb 2 S 2 GeTe InSbGe RAM Amorphous Crystalline In-Ag-Sb-TeRicoh 1996 650MB CD-RW (CD- Rewritable) 10 3 In-Ag- Relative Resistance Optical Reflectivity Sb-Te DVD-RW (2.6 GB/side) DVD+RW (3.0 GB/side) 72 14
3. -Te-Te-Te- (Viscosity) (Mobility) 80 (Stoichiometric Compound) 1986 IBM M. Chen TeGe Te(Crosslinking) TeGe 1/3~2/3 150 C 600 C Sn Sb As Se S O (Cyclability)(Noise) (Writability) (Archival Storage) (Erasability)(Readability) (Cyclability) Data-Storage Requirements Materials Constraint (writability) Easy glass former, low T m (archival storage) Stable T g (erasability) Fast crystallization (readability) Large signal-to-noise ratio (cyclability) Structure stability 150 C 1.5 ev 14 73
V/L (bit/sec)v (m/sec) L (µm/bit) λ (Numerical Aperture, NA) D=0.6λ/NA (Data Transfer Rate) GeSbTeGeTe Sb 2 Te 3 Sb Ni Pd Pt GeTe (Bandgap)0.8 ev 0.1 evcnr (Surface Roughness) (Voids) 10 6 GeSbTe2 10 6 CNR (Bit Error Rate, BER) IBM M. Chen CNR BER 74 14
1. 50 ns 2 ev 10 C/min. 150 C 2. Current Ith Vh Vth Voltage 1.4 100 C 600 C (V th ) (V th - V h )V th (Tg) (Nucleation and Growth) 01 Current (ma) 1.2 0.8 0.6 Read Programming Current Range 0 0.2 0.4 0.6 0.8 1 Device Voltage (V) Resistance (Ohms) Amorphous (solid) 0 R high R low Crystalline (solid) 1 Amorphous (liquid) Programming Current (ma) (I-V) 14 75
Minimum Nucleation Time Amorphizing RESET Pulse t 1 Amorphize After Pulse Ends (Write) Tm Write Pulse -100 nsec Erase Pulse (a) Liquid Crystal Amorphous Time T melt Nucleation Threshold 50 Time Minimum 10 Years Grain Growth Time Crystallize During Pulse (erase) 10 Years Complete Grain Growth Tx Ta (b) t 2 Crystallizing (SET) Pulse Time (T m ) 0 1 SETRESET 1. SET0 (t 2 ) (N&G) (Crystalline State) 2. RESET1 (t 1 ) (Amorphous State) (ns) 3.(READ) (T x ) (V a )RC Ovonyx Intel ECD ST Micro British Aerospace 2001IEDM Intel Ovonyx DRAM SRAM Flash MRAM FRAM 76 14
DRAM SRAM(6T) FLASH OUM MTJ-RAM FERAM Cell size (F^2) 6-12 50-80 7-11 5-8??? Large Volume @.18µM (F^3) 17 80 1 0.028??? Large Volatile/Non-volatile Volatile Volatile Non-volatile Non-volatile Non-volatile Non-volatile Endurance write/read / / 1E6/ >1E12/ >1E12/ 1E12/1E12 Read Destructive Partial-destructive Non-destructive Non-destructive Non-destructive Destructive Direct Over-write Yes Yes No Yes Yes Yes Bit/Byte Write/Erase Yes Yes Block Yes Yes Yes Read dynamic range (margin) 100-200mV 100-200mV Delta Current 10X-100XR 20-40%R 100-200mV Programming energy Medium Medium High Low Medium Medium Write/Erase/Read time 50ns/50ns/50ns 8ns/8ns/8ns 1µS/1-100ms(block)/60ns 10ns/50ns/20ns 30ns/30ns/30ns 80ns/80ns/80ns Transistors Low performance High performance High voltage High performance High performance Low performance CMOS Logic Compatibility Bad Good OK, but HiV req'd Good??? OK, but HiV req'd New Materials Yes No No Yes Yes Yes Scalability Limits Capacitor 6T Tunnel Oxide/HV Litho Current Density Polarizable Capacitor Multi-bit storage No No Yes Yes No No 3D Potential No No No Yes?????? SER Susceptibility Yes Yes No No No Yes Relative Cost per Bit Low High Medium Low??? High Top Electrode V A V A V A 5-15K V V V C n-1 ϕ SET ϕ RES V A I µa PGM 1 2.5 60 PGM 0 2.5 100 READ 2.5 <60 ϕ READ V REF Polycrystalline Chalcogeride Programmable Volume V REF Heater C n V A V A V A ϕ SET ϕ RES ϕ READ Bottom Electrode V REF C n+1 Row n-1 Row n Row n+1 ϕ SET ϕ RES ϕ READ (Memory Cell)(Circuit) 14 77
1.E+0.6 Resistance (Ohms) 1.E+0.5 1.E+0.4 SET pulse width 50ns RESET pulse width 30ns R SET 1.E+0.3 1.E+0 1.E+2 1.E+4 1.E+6 1.E+8 1.E+10 1.E+12 1.E+14 Number of Cycles Power to Reset in 5ns (W) 1.E-03 1.E-04 1.E-05 Polymer BPSG SiO 2 SiN x 0 500 1000 Diameter of Programmed Volume (Angstroms) (Transistor) (Heater) (V)(t) 10 13 (Polymer) (BPSG)(SiO 2 ) (SiN x ) MRAM FRAM (Non-volatile) DRAM SRAM Flash MRAM FRAM 78 14
2002Intel 0.184Mb 1. (Reliability) 2. Isolation 3. DRAM SRAM Flash. 4. MRAM MRAM FRAM MRAM FRAM 1. Stefan Lai (Intel) and Tyler Lowrey (Ovonyx), OUM - A 180 nm Nonvolatile Memory Cell Element Technology For Stand Alone and Embedded Applications IEDM, 2001 2. Technology presentation, http://www.ovonyx. com/ 14 79