a plasma doping process for 3d finfet source/ drain … materials external a plasma doping process...

Applied Materials External

A Plasma Doping Process for3D FinFET Source/ DrainExtensions

JTG 2014

Cuiyang Wang*, Shan Tang, Harold Persing,Bingxi Wood, Helen Maynard,Siamak Salimian, and Adam Brand

[email protected]

Varian Semiconductor Equipment | Silicon Systems Group


Outline

A Plasma Doping Process for 3D FinFET Source/ Drain Extensions

1. Plasma Doping for 3D FinFETs

2. Metrology for FinFET Doping Characterization

3. Doping Responses and Fin conductance

4. Summary and Acknowledgements

JTG Meeting, 20142


3D FinFET SDE Doping Challenges

3D FinFET for device 20nm beyond

Key Challenges:

► Conformal Doping

► No Fin erosion

► No residual defect

► Low leakage

JTG Meeting, 20143

Deposition andThermal Drive in

Highly Conformal Not PR compatible Cap layer

Title angle of implantation<10 deg

Plasma Doping:

Good conformality PR compatible

X+

1

2

3

X

X+

4

PLAD implant mode offers asimplified, photoresist compatible process

Beamline:

Shadowing


VIISta PLAD Advantages for Advanced Devices

4

• Production proven technology acrossmemory, logic and CIS process spaces

• Plasma Doping Advantages:

Pulsed DC bias allows for precision doping

Independent control of RF plasma generationand DC bias balances deposition and implant

Faraday dosimetry provides precision processtracking

All future devices are 3DPLAD can modify properties of vertical sidewalls

Sidewall dopingfor advanced 3D

devices:FinFET’s, VNAND,

and CIS

Sidewall dopingfor advanced 3D

devices:FinFET’s, VNAND,

CIS

Shallow doping toreduce contactresistance and

passivatesurfaces

High doseimplants to

modify materialproperties:

workfunction,etching rate, &conductivity.

JTG Meeting, 2014

Pulsed DC Bias

High DensityLow EnergyRF Plasma

Applied Materials ExternalIon Implant Technology, 2014

Benefits and Challenges for PLAD FinFET Doping

Various Process parameters:

− Power, Pressure, gas mixture ratio

− Energy, Dose, PW, Frequency

Doping of Si Fin structures is a driven by multiple mechanisms andcompeting effects

5

2: DEPOSITION andKNOCK-IN

3: REFLECTED IONIMPLANT

1: DIRECT IMPLANT

4: SPUTTERING

SiFin

X+

SiFin

1

2

3

X

X+

4

Multiple Mechanisms:− Direct implant− Deposition and knock in− Reflected implant− Sputtering/Etching

Wafer Results:− Conformality− Minimize fin erosion− Eliminate residual defects


Outline






JTG Meeting, 20142


Dopant Characterization Metrology

JTG Meeting, 2014

ABC

DE

A

B

C

D

E

1.5D SIMS

Fin resistor: active dopant

1. Lower detection limit2. Results can be quantified3. Average over number of fins4. No lateral resolution

EDS mapping/EDS line scans

1. 1% detection limit2. Lateral resolution3. Hard to quantify

Each metrology has its limitations and the characterization resultsneed to be interpreted carefully


Outline






JTG Meeting, 20142

Applied Materials External9 Ion Implant Technology, 2014

Start Wafer

PLAD Implant +Passivation

SPM clean

Anneal

PLAD ImplantApproach

Process Flow and Structure of Samples

PLAD implant mode offers a simplified, photoresist compatible process

Applied Materials MaydanCenter Fin Structure

Fin height: ~130nmFin width: ~50nmFin pitch: ~110nm

Si

9

Post DHF


1.E+19

1.E+20

1.E+21

200 250 300 350 400 450

SIM

SA

s(a

tm/c

m3

)

Depth (nm)

- A: Low Energy, Low Dose- B: Low Energy, High Dose- C: High energy, Low Dose- D: High Energy, High Dose

B

D

Implant Approach: Energy and Dose Tuning ofFin Doping

B

D

XTEM 1.5D SIMS

2D EDS

Tunable Fin doping is demonstrated by energy and dose control

JTG Meeting, 201410

2.0E+14

4.0E+14

6.0E+14

8.0E+14

1.0E+15

A B C D

Sid

ew

all

Do

se

(at/

cm

2) A

BC

D~50% increase

in AverageSidewall Dose

Fin height: ~130nm, Fin width: ~50nm, Fin pitch: ~110nm


1E+19

1E+20

1E+21

200 300 400S

IMS

As

(Ato

ms

/cm

3)

Depth (nm)

DR1

DR1

DR3

DR3

Implant Approach: Plasma Process ParameterTuning of Fin Doping

Fin doping can be further optimized by plasma parameter tuning

XTEM1.5D SIMS

2D EDS

JTG Meeting, 201411

- DR1: Dose Rate 1- DR2: Dose Rate 2- DR3: Dose Rate 3

5.0E+14

7.0E+14

9.0E+14

1.1E+15

1.3E+15

DR1 DR2 DR3

Sid

ew

all

Do

se

(at/

cm

2)

DR1

DR2

DR3 ~36% increase inaverage sidewall

Dose



Implant Approach: EDS Verification ofDopant into Fin Sidewall

JTG Meeting, 2014

0

1

2

3

4

5

0

20

40

60

80

100

1 2 3 4 5 6 7 8 9

As

Co

mp

os

itio

n(%

)

Sio

rO

co

mp

os

itio

n(%

)

EDS Line Scan Site

O

Si

As

EDS as-implanted line scan demonstrates As doping into fin sidewall

Si Fin SiO2

Si Fin

12



Outline






JTG Meeting, 20142


Summary

Plasma doping of Fin structures by an implant based approachhas been demonstrated

The application of plasma doping into logic device technology israpidly accelerating

Efforts to enhance fundamental understanding and to enablepredictive approaches are in progress

As 3D transistor technology continues to be implemented, PLADwill be required for doping and material property modification

14 JTG Meeting, 2014


Acknowledgements

Appreciation is extended to Alexander Pagdanganan, MartinHilkene, and Matthew Castle for providing the poly-silicondeposition and process flows at the Maydan Center

We would also like to thank Peter Ryan for his support of theplasma doped sample preparation

JTG Meeting, 201415

a plasma doping process for 3d finfet source/ drain … materials external a plasma doping process...

Documents