Material Engineering for 7nm FinFETs

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Terence Byrd
5 years ago
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Stress Engineering at 14 nm Node NMOS: Low Stress PMOS: High Stress Junct ion Si Si

Common SRB Epi for NMOS & PMOS Wafer before fin

of 360 nm, it is impractical to have separate SRB

9 Common SRB Epi for NMOS & PMOS Wafer before fin patterning Standard cell row Another cell row Ge SiGeSn channel PMOS NMOS PMOS SiGe SRB SiGe SRB Si wafer Si wafer Considering cell heights (pitches) of 360 nm, it is impractical to have separate SRB s for NMOS and PMOS 2014 Synopsys. All rights reserved. 9

10 7nm Stress Engineering: SRB + S/D Epi Si channel SiGe channel Ge channel NMOS Si Si 15% Ge 50% Ge 30% Ge Ge +1.5 GPa 25% Ge 50% Ge 75% Ge PMOS -1.5 GPa 70% Ge Si 85% Ge 50% Ge Ge Ge 25% Ge 50% Ge 75% Ge 2014 Synopsys. All rights reserved. 10 Stress analysis in S-Process

11 Ballistic Ratio Ballistic Transport Evolution Relaxed 2 GPa Ballistic transport is currently ~64% Is expected to rise to ~84% at 7nm node nm 0.41 Even higher for Ge and InGaAs nm nm 5nm technology node Channel Length, nm Therefore, ballistic transport approximation is reasonable for 7nm node Si NMOS FinFET with 6nm wide fin 2014 Synopsys. All rights reserved. 11 Calculated in Sentaurus Monte Carlo

13 Drain current, A/um Stress Free SiGe: IdVg Curves Vdd = 0.7 V in this project BTBT model calibrated by IMEC Ge Higher Ge % Si Gate bias, V 2014 Synopsys. All rights reserved. 13 3D analysis in S-Device

14 Ion, ua/um Strained SiGe: 2 GPa Tensile Stress 3000 SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP , ,900 2,003 1,902 HP: 100 na/um (Servers) ,233 1,310 1, SP: 1 na/um (Laptops) LP: 50 pa/um (Mobile) Germanium mole fraction 2014 Synopsys. All rights reserved. 14 7nm NMOS FinFET

15 Ion, ua/um Strained SiGe: 2 GPa Tensile Stress SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP Flat Dip 2,429 Best ,900 2,003 1,902 HP: 100 na/um ,233 1, Gone 1,054 SP: 1 na/um LP: 50 pa/um 0 Germanium mole fraction 2014 Synopsys. All rights reserved. 15 7nm NMOS FinFET

16 Inversion charge, 1/cm2 Injection velocityj, cm/s Strained SiGe: N inv and V inj 1.2E+13 SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP 3.E+07 SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP 1.0E E+12 2.E E E+12 1.E E E+00 Germanium mole fraction 0.E+00 Germanium mole fraction 2014 Synopsys. All rights reserved. 16 7nm NMOS FinFET

$0E+00 Germanium mole fraction Germanium mole fraction Here, Vgs = 0.$

17 Valley occupancy % Ninv (1/cm2) Delta & Lambda Valley Population 100% 2.0E+12 80% X 1.5E+12 Absolute 60% Relative 1.0E+12 X L 40% 20% L 5.0E+11 0% 0.0E+00 Germanium mole fraction Germanium mole fraction Here, Vgs = 0.7 V and gate WF is adjusted to have min Ioff at Vgs = 0 There are too few electrons at 80% to 90% Ge mole fractions 2014 Synopsys. All rights reserved. 17 S-Band

18 Ion, ua/um Strained SiGe: LP, SP & HP Champions 3000 SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP ,900 2,003 1,902 2,429 HP: Ge ,233 1, ,054 SP: Mid-range SiGe LP: Si 0 Germanium mole fraction 2014 Synopsys. All rights reserved. 18 7nm NMOS FinFET

$fraction Better NMOS s Only Si and SiGe with low Ge % can match LP spec HP performance penalty to pure Ge is ~20% The choice between pure Si vs SiGe with low Ge % can be made based on PMOS/NMOS$

19 Ion, ua/um Strained SiGe: Combination Champion 3000 SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP 2, ,003 1,900 1, ,233 1,310 1, Germanium mole fraction Better NMOS s Only Si and SiGe with low Ge % can match LP spec HP performance penalty to pure Ge is ~20% The choice between pure Si vs SiGe with low Ge % can be made based on PMOS/NMOS stress trade-off Better PMOS s 2014 Synopsys. All rights reserved. 19 7nm NMOS FinFET

23 Bandgap, ev stress Bandgap, ev confinement confinement Band Gap Widening and Narrowing SiGe InGaAs Bulk Strained narrow fin Stress-free narrow fin Bulk Narrow fin Germanium mole fraction Gallium mole fraction For SiGe, 6nm wide fin widens bandgap by 40 mv to 50 mv Tensile uniaxial 2 GPa stress pushes it down by 70 mv to 100 mv For GaAs, the widening is 155 mv, and for InAs it grows to 340 mv 2014 Synopsys. All rights reserved. 23 7nm NMOS FinFET

$7 Bulk Strained narrow fin Stress-free narrow fin 0.4 0.2 Bulk Narrow fin 0.6 0.0 Germanium mole fraction Gallium mole fraction High mobility materials need to have bandgap wider than silicon!$

24 Bandgap, ev stress Bandgap, ev confinement confinement Band Gap Widening and Narrowing LP Ioff spec 1.1 SiGe InGaAs Bulk Strained narrow fin Stress-free narrow fin Bulk Narrow fin Germanium mole fraction Gallium mole fraction High mobility materials need to have bandgap wider than silicon! 2014 Synopsys. All rights reserved. 24 7nm NMOS FinFET

25 Valley occupancy % Valley occupancy % Gamma, Delta & Lambda Valleys 100% 80% X 100% 80% G 60% 40% SiGe 60% 40% InGaAs 20% L 20% L 0% Germanium mole fraction 0% Gallium mole fraction 2014 Synopsys. All rights reserved. 25 7nm NMOS FinFET

26 Inversion charge, 1/cm2 Injection velocityj, cm/s Group IV vs III-V: N inv and V inj InGaAs LP InGaAs SP InGaAs HP SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP 1.2E+13 6.E E+13 5.E E+12 4.E E+12 3.E E+12 2.E E+12 1.E E+00 0.E+00 Mole fraction (Germanium or Gallium) Mole fraction (Germanium or Gallium) 2014 Synopsys. All rights reserved. 26 7nm NMOS FinFET

27 Ion, ua/um Group IV vs III-V InGaAs LP InGaAs SP InGaAs HP SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP 2,612 2,589 2,449 2, ,900 2,003 1,977 1, ,233 1, , Mole fraction (Germanium or Gallium) Synopsys. All rights reserved. 27 7nm NMOS FinFET

28 Ion, ua/um Group IV vs III-V: LP, SP & HP Champions InGaAs LP InGaAs SP InGaAs HP 3000 SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP ,900 2,449 2,612 2,589 2,003 1,977 1,902 2,429 HP: Mid-range InGaAs 1500 SP: 30% In InGaAs 1,233 1, , LP: Si 0 Mole fraction (Germanium or Gallium) Synopsys. All rights reserved. 28 7nm NMOS FinFET

$Si, low Ge SiGe, and GaAs can match LP spec InGaAs with 10% In has competitive performance, but is too sensitive to In content 1,233 1,310 1,054 1000 970 722 638 601 500 0 Mole fraction (Germanium or$

29 Ion, ua/um Group IV vs III-V: Combination Champion InGaAs LP InGaAs SP InGaAs HP SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP 2,612 2,589 2,449 2,429 2,003 1,900 1,902 1,977 Only Si, low Ge SiGe, and GaAs can match LP spec InGaAs with 10% In has competitive performance, but is too sensitive to In content 1,233 1,310 1, Mole fraction (Germanium or Gallium) This would bring severe variability So, silicon looks the best SiGe with low Ge % can be used for stress engineering 2014 Synopsys. All rights reserved. 29 7nm NMOS FinFET

30 Ion, ua/um 0.5 V Vdd Instead of 0.7 V Vdd InGaAs LP InGaAs SP InGaAs HP SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP 1,962 1,547 1,651 1,510 1,239 1,131 1,082 1,211 1,090 1,064 InGaAs with 30% In really shines at SP and HP specs Nobody can pull off LP at 0.5 V Vdd. Would you like your iphone to be ~30x slower? Mole fraction (Germanium or Gallium) To have 0.5 V Vdd, variability has to go down ~2x. That is a stretch. The best InGaAs composition has Silike bandgap 2014 Synopsys. All rights reserved. 30 7nm NMOS FinFET

Summary It is a close race, no clear winner The best choice depends on

Design-Technology Co-Optimization for 5nm Node and Beyond

Design-Technology Co-Optimization for 5 Node and Beyond Semicon West 26 Victor Moroz July 2, 26 Why Scaling? When What scales? When does it end? 965 999 2 Moore s Law (Fairchild): Double transistor density