LAYOUT EFFECTS HOW LAYOUTS CAN CHANGE CMOS AND

“LAYOUT” EFFECTS HOW LAYOUTS CAN CHANGE CMOS AND HOW DO CIRCUIT SIMULATIONS ACCOUNT FOR THE CHANGE BOB PEDDENPOHL MODELING MANAGER CYPRESS MODELING CENTER LEXINGTON, KY 04/04/07

AGENDA (ACRONYM TEST) BSIM BASICS, NEW FEATURES BERKLEY SHORT CHANNEL IGFET MODEL STI EFFECT OR LOD EFFECT SHALLOW TRENCH ISOLATION OR LENGTH OF DIFFUSION WPE WELL PROXIMITY EFFECTS OPC OPTICAL PROXIMITY CORRECTION 2 Cypress Confidential

AGENDA BSIM BASICS, NEW FEATURES LENGTH-OF-DIFFUSION (LOD) WELL PROXIMITY EFFECTS (WPE) OPTICAL PROXIMITY CORRECTION (OPC) 3 Cypress Confidential

BSIM BASICS SPICE SIMULATION OF MOS (ONLY APPROXIMATIONS!) HAND CALC: Ids = width/length * Cox * Mobility * (Vgs – Vth - Vdsat) * Vds SPICE CALC: Ids = w/l * 1/TOX * U 0 * (Vgs – VTH 0 – VDSAT) * Vds TERMINOLOGY SPICE MODEL PARAMETERS (BSIM 3 PARAMETERS) INSTANCE PARAMETERS SIMULATION PARAMETERS (BIAS CONDITIONS) MODEL EXAMPLE: . model nshort. 1 nmos TOX = 4. 19 e-9 NETLIST EXAMPLE: m 1 d g s b nshort w =25 l=0. 5 m=1 ad=50 pd=27. . delvth 0=0. 0 sa=1. 04 sb=1. 04 v 1 g s 1. 8 v 2 d s 0. 9 v 3 b s 0. 0 COMMAND RUN EXAMPLE spectre mynetlist. scs WAVEFORM VIEWER TO REVIEW SPECTRE OUTPUT FILES 4 Cypress Confidential

BSIM 3 VS BSIM 4 WHAT ARE UPGRADES IN BSIM 4? LOD WPE RF MODELING IMPROVEMENTS BSIM: http: //www-device. eecs. berkeley. edu/~bsim 3/ BSIM = BERKELEY SHORT-CHANNEL IGFET MODEL 5 Cypress Confidential

MODEL DEVELOPMENT PROCESS SELECT “GOLDEN” WAFER MEASUREMENT (DC, AC, TRAN) EXTRACT WAFER CASE MODEL RO MEAS = RO SIMS CENTER TO EDR NOMINAL (TT) SKEW MODELS (FF, SS, FS, SF) QA & RELEASE TO DESIGN 6 Cypress Confidential

AGENDA BSIM BASICS, NEW FEATURES LENGTH-OF-DIFFUSION (LOD) WELL PROXIMITY EFFECTS (WPE) OPTICAL PROXIMITY CORRECTION (OPC) 7 Cypress Confidential

LAYOUT CHOICES & LOD § BEST VALUE FOR Sa, Sb? WHY BIGGER DIFFUSIONS? Sa Sb Sa 8 Cypress Confidential Sb

MEASURED DATA § VTH DUE TO STI STRESS Sa, Sb Instance params for LOD Sa STI Effect Proximity Effect 9 Cypress Confidential Sb Sa Sb

LOD MODEL EQUATIONS Sa ELECTRICAL PARAM SPICE/MODEL EQN (APPROX) MODEL FITTING CURVE Vth VTH 0 + KVTH 0 Vth vs Sa, Sb Vth w/ Vbs Vth + K 2 + STK 2 Vth@Vbs vs Sa, Sb Ids_linear (Ids vs Vds) Mobility = U 0 + KU 0 Idslin vs Sa, Sb Ids_sat Vsat = VSAT + KVSAT Ids vs Sa, Sb Rout (Output Resistance) Rout = 1/Gds + STETA 0 Rout vs Sa, Sb STRESS MODEL PARAMETERS f(Sa, Sb) 10 Cypress Confidential Sb

SPICE WITH LOD EFFECTS § BEST VALUE FOR Sa, Sb? WHY? Sa 11 Sb Sa Sb § NETLIST WITH LOD m 1 d g s b nshort w =25 l=0. 5 m=1 ad=50 pd=27. . delvth 0=0. 0 sa=1. 04 sb=1. 04 § IDS SPICE APPROX WITH LOD SPICE CALC: Ids = w/l * 1/TOX * (U 0 + KU 0) * (Vgs – VTH 0 – VDSAT) * Vds § ALTERNATIVES TO MODELING? § MODEL INSTANCE PARAMETERS + MODEL PARAMETERS § DRC ENFORCE SINGLE SA, SB VALUE ALLOWED § CORNER MODELS PUT WIDER VARIATION INTO MODEL § ADVANTAGES/DISADVANTAGES? § SIMULATION TIME & ACCURACY, MODEL DEVELOPMENT TIME § SILICON AREA INCREASES Cypress Confidential

AGENDA BSIM BASICS, NEW FEATURES LENGTH-OF-DIFFUSION (LOD) WELL PROXIMITY EFFECTS (WPE) OPTICAL PROXIMITY CORRECTION (OPC) 12 Cypress Confidential

WPE BACKGROUND nwell Wspc 13 § WHAT’S THE CAUSE? § http: //www. ieee-cicc. org/06 -8 -6. pdf Cypress Confidential

RECALL PROCESSING STEPS 14 Cypress Confidential

NWELL IMPLANT EFFECTS CMOS 15 § HIGH ENERGY ATOMS BOUNCE OFF PHOTORESIST § http: //www. ieee-cicc. org/06 -8 -6. pdf (see paper diagrams) § WHY WPE NOW? § SPICE MODEL OF WPE § REFERENCE: § HIGH ENERGY IMPLANTERS § WANT DEEP IMPLANT LOW RES PATH SUPRESS BJT LATCHUP § Vth = VTH 0 + KVTHOWE*(sca+WEB*scb + WEC*scc) § Vth@Vbs = K 2 + K 2 WE * (sca + WEB*scb +WEC*scc) § Mobility = U 0 * (1+KU 0 WE*(sca + WEB*scb+WEC*scc) § COMPACT MODEL COUNCIL WEBSITE § BSIM 4 MANUAL FROM BERKELEY WEBSITE Cypress Confidential

SPICE WITH WPE EFFECTS nwell § INSTANCE PARAMS ALL FUNCTION Wspc § Sca, scb, scc Wspc 16 ELECTRICAL PARAM SPICE/MODEL EQN (APPROX) MODEL FITTING CURVE Vth VTH 0 + KVTHOWE*(sca+WEB*scb + WEC*scc) Vth vs sca, scb, scc Vth w/ Vbs Vth + K 2 WE * (sca + WEB*scb +WEC*scc) Vth@Vbs vs sca, scb, scc Mobility U 0 * (1+KU 0 WE*(sca+WEB*scb+WEC*scc) IDS Lin vs sca, scb, scc § NETLIST WITH WPE § IDS SPICE APPROX WITH WPE § ADVANTAGES/DISADVANTAGES/ALTERNATIVES? m 1 d g s b nshort w =25 l=0. 5 m=1 ad=50 pd=27. . delvth 0=0. 0 sca=1. 1 scb=0. 5, scc=3 SPICE: Ids = w/l * 1/TOX * (U 0 + f(KU 0 WE) * (Vgs – VTHO + f(KVTHOWE) – Vdsat) * Vds Cypress Confidential

AGENDA BSIM BASICS, NEW FEATURES LENGTH-OF-DIFFUSION (LOD) WELL PROXIMITY EFFECTS (WPE) OPTICAL PROXIMITY CORRECTION (OPC) 17 Cypress Confidential

RF FET Modules Layout With poly proximity bars M=2 M=4 Standard Layout Without poly proximity bars Is performance the same? 18 Cypress Confidential

OPC BACKGROUND OPTICAL PROXIMITY CORRECTION (OPC) DURING LIGHT EXPOSING OF PHOTORESIST FINAL SHAPES ON SILICON NOT MATCH DRAWN SHAPES BASED ON SURROUNDING ENVIRONMENT With proximity bars Standard Layout Without proximity bars 19 Cypress Confidential

MEASURED DATA § VTH DUE TO STI STRESS Sa, Sb Instance params for LOD Sa STI Effect Proximity Effect 20 Cypress Confidential Sb Sa Sb

MEASURED DATA § VTH DUE TO PROXIMITY AND STI STRESS STI Effect Proximity Effect 21 Cypress Confidential

DRAWN NOT EQUAL FINAL OPC “SIMULATION” TOOL IN: LAYOUT, OUT: POLY SHAPES Lcenter Ledge Ltrans 22 W/L/M Lcenter Ledge Ltrans 3/0. 15/2 0. 15 0. 214 0. 17 Cypress Confidential

M=2 AND M=4 COMPARISON W/L/M Lcenter Ledge Ltrans 3/0. 15/2 0. 15 0. 214 0. 17 3/0. 15/4 (edge) 0. 15 0. 204 0. 185 3/0. 15/4 (center) 0. 15 0. 234 0. 185 § 23 Cypress Confidential SAME DRAWN L, BUT SILICON VARIES

DESIGNING WITH OPC 24 § NO SPICE MODEL EFFECT § RELY ON CLDRC, NOT PERFECT § ACCOUNT FOR IN YOUR DESIGN? § L(DRAWN) = L(SI) Cypress Confidential

MEASURED DATA § VTH DUE TO PROXIMITY AND STI STRESS Sa STI Effect Proximity Effect 25 Cypress Confidential Sb Sa Sb

CONCLUSIONS § LOD/WPE IMPACT TRANSISTOR PERFORMANCE, ACCOUNT FOR BY: § NEW PHYSICAL EFFECTS RELY HEAVILY ON INSTANCE PARAMETERS OR CLDRC § MODEL ACCURATE AT COST OF MODEL DEVELOPMENT § DRC RULES EASIER DESIGN KIT AT COST OF AREA § INTERACTION OF THE MODEL WITH CAD TOOLS § 26 GOOD DESIGNER: § LIMIT THESE EFFECTS AS MUCH AS POSSIBLE IN LAYOUT § REVIEW MODELS TO ENSURE EFFECTS ARE INCLUDED Cypress Confidential

APPENDIX

EXECUTIVE SUMMARY § PROBLEM STATEMENT § TRANSISTOR PARAMETRIC SHIFTS DUE TO PROXIMITY EFFECTS ð PHOTO/ETCH: DENSE VS ISOLATED ð STI STRESS: POLY-STI EDGE SPACING § WHAT WAS DONE § ELECT/OPTICAL CHAR OF DENSE VS ISOLATED ON L 8 § PHOTO/ETCH VS STI STRESS CHAR ON S 8 § 28 WHAT NEEDS TO BE DONE (TO BE FORMALIZED) Cypress Confidential

MEASUREMENTS: COMPLETE MOS § § 29 FET DC (VTH 0, RDSW) FET AC (CGDO, DLC) DIODE DC (JS, JSW) DIODE AC (CJ, CJSW) Cypress Confidential

Stress Equations in Model § Measurements done by SBJ § As NMOS gets closer to STI Edge, VT Increases, IDS and Gm Decrease § As PMOS gets closer to STI Edge, |VT| Decreases, IDS and Gm Increase. § STI induced Stress degrades NMOS and enhances PMOS characteristics (why enhanced? ) § More measurements are planned. § Data is plotted for # of proximity bars and length of diffusion (LOD). 30 Cypress Confidential

W=3. 01 L=0. 15 M 2 § L = 0. 158 -0. 008=0. 15 um at center § L=0. 222 -0. 008 = 0. 214 um at edge § Transition region from edge before L becomes 0. 15 um 0. 17 um § Impact will be larger for W=1. 65 31 Cypress Confidential

W=3. 01 L=0. 15 M 4 § L = 0. 158 -0. 008=0. 15 um at center § L=0. 232 -0. 008 = 0. 234 um at edge of center two fingers § L=0. 212 -0. 008 = 0. 204 um at edge of outer fingers § Transition region from edge before L becomes 0. 15 -0. 155 um = 0. 185 um 32 Cypress Confidential