R Si Project SHANa Damage O Ar 0.543 nm 2014.05.12 PESM Koji - - PowerPoint PPT Presentation

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R Si Project SHANa Damage O Ar 0.543 nm 2014.05.12 PESM Koji - - PowerPoint PPT Presentation

Dec 28, 2022 545 likes •786 views

Plasma-Induced Damage in 3D Structures behind Device Scaling K. Eriguchi, Y. Takao, and K. Ono Kyoto University, JAPAN Acknowledgements: This work was partly supported by JSPS and STARC project in Japan. Plasma R Si Project SHANa Damage

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2014.05.12 PESM Koji Eriguchi

  • K. Eriguchi, Y. Takao, and K. Ono

Kyoto University, JAPAN Acknowledgements: This work was partly supported by JSPS and STARC project in Japan.

Plasma-Induced Damage in 3D Structures behind Device Scaling

Damage

R

Project SHANa

Plasma

Si O Ar

0.543 nm

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2014.05.12 PESM Koji Eriguchi

Outline Outline

  • 1. Introduction – Plasma-Induced Damage (PID)
  • 2. A Scenario for PID in Scaled 3D Structures

2-1 PID Models – Straggling & Sputtering 2-2 Molecular Dynamics Simulation 2-3 Electronic State of Defect

  • 3. PID Prediction in 3D Structure

4．Summary

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2014.05.12 PESM Koji Eriguchi

Plasma-Induced Damage (PID)

Plasma

Performance Reliability Yield Variability

PID naturally does not scale!!

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PID behind the scaling

Plasma-Induced Physical Damage (PPD) Power consumption increase & Operating speed down!!

Auth, VLSI 2012. Mistry, IEDM 2007.

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Previous reports on PID

  • S. A. Vitale and B. A. Smith: JVST B 21 (2003) 2205.
  • N. Yasui et al.: Proc. Symp. Dry Process (2007) 195.
  • T. Ohchi et al.: Jpn. J. Appl. Phys. 47 (2008) 5324.
  • H. Kokura et al., Proc. Symp. Dry Process, 2005, p. 27.

Presence of defects

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2014.05.12 PESM Koji Eriguchi

Outline Outline

  • 1. Introduction – Plasma-Induced Damage (PID)
  • 2. A Scenario for PID in Scaled 3D Structures

2-1 PID Models – Straggling & Sputtering 2-2 Molecular Dynamics Simulation 2-3 Electronic State of Defect

  • 3. PID Prediction in 3D Structure

4．Summary

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2014.05.12 PESM Koji Eriguchi

Gate Plasma (ne, Te, nion) ion Eion Si substrate

E 

ndam(x) x Si

Project Range  Stopping Power Project Range  Stopping Power

pdp p E T n E S n dx dE  2 ) , ( ) (

ion ion d ion

      

Potential-model-dependent

T: energy transfer p: impact parameter

 

1 n

5 . ) ( B s

low energy limit (Wilson model:  ~ 0.3)

  • N. Bohr: Mat. Fys. Medd. K. Dan. Vidensk. Selsk. 18 (1948).
  • J. Lindhard et al.: Mat. Fys. Medd. K. Dan. Vidensk. Selsk. 33, 1 (1963).
  • G. Moliere: Z. Naturforschung A2, 133 (1947).
  • W. D. Wilson et al.: Phys. Rev. B 15, 2458 (1977).

: reduced energy

x Rp p

Straggling Range

PID Range Theory – Planar Device

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2014.05.12 PESM Koji Eriguchi

PID Range Theory – Planar Device

ion Si radical Mask Si Plasma ion Etching

Damaged layer

Rp p

  • ex. Si Recess

) (

ion ion p

E A R  

p ion Si ion Si p

3 2 R M M M M   

(Eriguchi et al.) (LSS Theory)

p p V

   R d

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PID Range Theory – "Straggling"

Gate ion

Eion

Si sub.

Plasma

Mask

(a) Planar (1D)

Damaged layer Defect

(b) Fin-structured (3D) Etching

“Lateral straggling”

L

Rp & p Rp p

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PID Range Theory – "Straggling"

Mask

Etching

“Lateral straggling”

L

Rp p

) (

ion ion p

E A R  

p ion Si ion Si p

3 2 R M M M M   

p L

    K

(Eriguchi et al.) (LSS Theory) (Furukawa et al.)

 ) ( 3 2

ion ion Si ion Si ion L

E M M M M B   

(1) Lateral straggling depends on Mion, Eion, and Si–ion potential. (2) Sidewall etching mechanism is governed, not only by direct ion impact & deposition, but also by THIS STRAGGLING, L!  Damaged layer thickness ~ Rp + p (planar), L (3D)

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PID Model – 3D Device

Lateral straggling Sputtering

Mask Si Plasma ion  L ion Si radical

 

th ion sp sp

E E A    

p p L

R   

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2014.05.12 PESM Koji Eriguchi

Outline Outline

  • 1. Introduction – Plasma-Induced Damage (PID)
  • 2. A Scenario for PID in Scaled 3D Structures

2-1 PID Models – Straggling & Sputtering 2-2 Molecular Dynamics Simulation 2-3 Electronic State of Defect

  • 3. PID Prediction in 3D Structure

4．Summary

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Simulation scheme

Classical Molecular Dynamics

Si–Si, Cl, O: Stillinger–Weber

  • Phys. Rev. B, Vol.31, No.8, (1985), pp. 5262-5271

Noble gases: Wilson et al.

  • Phys. Rev. B, Vol.15, No.5, (1977), pp. 2458-2468

(Ohta and Hamaguchi, JVST 2001.)

Starting material Si Si Ne Defect analysis by dumbbell Si Interstitial ions

Density Functional Theory

Local defect Surface layer

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MD prediction results in Fin

Ar ion 100 eV (normal) Cl ion 100 eV (normal)

Si Ar Cl

dumbbell dumbbell Interstitial Interstitial

Sputtering Sputtering Lateral straggling Lateral straggling

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Defect creation in Fin

Counting the defects in this region one by one in accordance with the bond order and length.

100 200 300 400 100 200 300 400 500 0 100 200 300 400 500 Eion (eV) Eion (eV) Counts Ne Ar Xe Kr F Cl Br

An ion with lighter mass and higher incident energy  larger damage An ion with lighter mass and higher incident energy  larger damage

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Defect creation in "Fin"

5 10 15 20 25 30 0.0 1.0 2.0 3.0 4.0 5.0 Incident particle counts Distance from fin edge (nm) Fin region Damage layer F Cl Br 100 200 300 400

50 eV 100 eV 200 eV 400 eV

Defect counts 5 10 15 20 25 F Cl Br Particle counts fin body

“fin”

Both "sputtering" and "straggling" are responsible for PID in 3D. Both "sputtering" and "straggling" are responsible for PID in 3D. sputtering straggling

E = 200 eV

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Outline Outline

  • 1. Introduction – Plasma-Induced Damage (PID)
  • 2. A Scenario for PID in Scaled 3D Structures

2-1 PID Models – Straggling & Sputtering 2-2 Molecular Dynamics Simulation 2-3 Electronic State of Defect

  • 3. PID Prediction in 3D Structure

4．Summary

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Electronic structure of defect

Original super-lattice structure 40 80 120

  • 3.0
  • 2.0
  • 1.0

0.0 1.0 2.0 3.0 Density-of-state (arb. u.) Energy (eV)

DFT: 6-31G with PBEPBE & PBC

Damage

dumbbell He interstitial Ar interstitial No damage

0.0 0.4 0.8 1.2 0.0 0.2 0.4 0.6 0.8 Band gap energy (eV) Distance from lattice site (A) Displaced Si Displaced Si

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Experimental evidence

1017 1018 1019 1020 0.0 5.0 10.0 15.0 20.0

400 kHz 13.56 MHz no bias S.P.100W

Defect density: ndam (cm-3)

CV

dc plasma

V V 

(V1/2)

ndam Shield Stage Sample Control PC Vg Hg SiO2 Si

Eriguchi IEDM 2008 / Kamei Thin Solid Films 518 (2010) / Nakakubo AVS 2011

Defect Density ~ 1018 - 1019 cm-3

Ar plasma

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2014.05.12 PESM Koji Eriguchi

Outline Outline

  • 1. Introduction – Plasma-Induced Damage (PID)
  • 2. A Scenario for PID in Scaled 3D Structures

2-1 PID Models – Straggling & Sputtering 2-2 Molecular Dynamics Simulation 2-3 Electronic State of Defect

  • 3. PID Prediction in 3D Structure

4．Summary

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PID prediction in Fin-structure

Assumption: (1) PID is modeled by the present scheme. (2) Surface damaged layer was stripped off. (3) Latent-defect creation was uncorrelated. ~30 nm ~20 nm ~10 nm ~5 nm

! ) exp( ) (

MD dam dam MD

MD

n n n n P

n

   

MD dy n E dx x n

x ion ion dam

) ( ) (     

 PID Range Theory

?

Experiment in planar structure ndam ~ 1018 - 1019 cm-3

 ) ( 3 2

ion ion Si ion Si ion L

E M M M M B    Present Models Typical PID: Ar 200 eV np ~ 1011 cm-3

One in ~ every two snapshots

Typical fin size

 

th ion sp sp

E E A    

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2014.05.12 PESM Koji Eriguchi

Outline Outline

  • 1. Introduction – Plasma-Induced Damage (PID)
  • 2. A Scenario for PID in Scaled 3D Structures

2-1 PID Models – Straggling & Sputtering 2-2 Molecular Dynamics Simulation 2-3 Electronic State of Defect

  • 3. PID Prediction in 3D Structure

4．Summary

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Summary

Plasma-induced damage in 3D structures were discussed. (1) A new PID model was proposed on the basis of (A) lateral straggling at the etched surface and (B) bombardment of sputtered species at the sidewall. (2) A model prediction and MD simulations suggest that both the lateral straggling and the sputtered particle bombardment will become responsible for PID in scaled 3D structures. One should revise the views of plasma etching at the sidewall because the lateral PID is no longer negligible in ultimately scaled 3D devices.