Advances in Directly Patternable Metal Oxides for EUV Resist

Andrew Grenville

EUVL Symposium 2013 Toyama, Japan

Conventional Photoresists Stretched to the Limit

© IMEC 2010

UNDERLAYER SCREENINGProfiles for 28nm LS (Resist B)

M.GOETHALS- EUVL 2010, KOBE, OCTOBER 18, 2010

13

11.8mJ/cm228L56P

13.2mJ/cm228L56P

Standard UL(on track), 20nm

UL8 , 10nm

12mJ/cm228L56P

UL3 (on track), 10nm

12.mJ/cm2

12mJ/cm228L56P

28L56P

UL5, 10nm

UL6, 10nmUL12, 10nm

12mJ/cm228L56PDifferent Underlayer showed only minor differences in LER, and process windowsStandard UL and UL12 showed the lowest LER and reasonable PW

© IMEC 2010

Benchmarking 28nm L/S, 50nmFT

STD UL

20nm

UL310nm

RESIST A RESIST B RESIST C

15M.GOETHALS- EUVL 2010, KOBE, OCTOBER 18, 2010

14.3 mJ/cm2

LER=4.2nm12.4mJ/cm2

LER=4.2nm15.2 mJ/cm2

LER=4.3nm

14.5 mJ/cm2

LER=4.4nm12.0mJ/cm2

LER=4.6nm15.2mJ/cm2

LER=4.3nm

Resist B on std underlayer shows highest sensitivity and lowest LER

P-12

2012 International Symposium on Extreme Ultraviolet Lithography

FUJIFILM Corporation October 1, 2012

Proof of concept, high CA resist

25.0 nm L/S 22.5 nm L/S 20.0 nm L/S

50 keV point beam 40 nm film thickness

High CA polymer-B has a advantage on collapse

25.0 nm L/S 22.5 nm L/S 20.0 nm L/S Collapsed Collapsed Collapsed

FEVS-P1507D: High CA, new polymer-B

FEVS-P1293A: Low CA, conventional polymer

Resolution

Line Width Roughness

Pattern Collapse

Patternable Metal Oxides

Goal: Design photoresists with small, inorganic building blocks

Resolution & LWR

Etch Selectivity

EUV Absorbance

Low Blur

Metal oxide clusters

Gen 1 Materials: EUV Imaging

8 nm l/s LWR 1.5nm

10 nm l/s LWR 0.7 nm

Inpria Generation 1 EUV Photoresists

High Developer Concentration

High Imaging Dose

Instability: shelf life and process

Image Fidelity (res & LWR)

Etch Resistance

High EUV absorbance

Gen 1

Competing condensation and dehydration processes

10 nm l/s, 0.7 nm LWR

New Platform Solves Key Challenges

Standard Developers

Path to required dose

Shelf stable and vacuum stable

High Developer Concentration

High Imaging Dose

Instability: shelf life and process

Image Fidelity (res & LWR)

Etch Resistance

High EUV absorbance

Image Fidelity (res & LWR)

Etch Resistance

High EUV absorbance

Gen 1 Gen 2

Inpria’s Patterning Mechanism

H

L*

O

O

L*

H M M O

O M M + H2O, L*

7 秘 SPC-1K5240210006 TOSHIBA Confidential

100nm 50nm 40nm 30nm

26nm 24nm 22nm 20nm

Pattern resolution check 3space pattern (750uC/cm2)

Resolution limit in 3space pattern is about 22nm. It has good resist profile around 20nm pattern.

Bake

Develop L*

O

O

L*

M M H H

Metal hydroxo clusters Dense metal oxide film

Exposure generates high solubility contrast

in developer

L* = radiation sensitive ligand

Unpatterned film

Patterned film

New molecular oxide clusters and ligand chemistries

adopted for Gen 2 materials

18nm hp

Gen 2 E-Beam Baseline: YA Series

n-BA develop 20nm FT, ~1100µC/cm2

18nm hp

26nm hp

Gen 2 E-Beam Baseline: YA Series

14nm hp 16nm hp

16nm hp

14nm hp

12nm hp

0"

0.4"

0.8"

1.2"

1.6"

2"

2.4"

2.8"

3.2"

3.6"

4"

8"

10"

12"

14"

16"

18"

20"

22"

24"

26"

28"

0" 20" 40" 60" 80" 100" 120"

LWR"(nm)"

CD"(n

m)"

Shelf"Storage"at"Room"Temperature"(Days)"

Resist"ShelfClife:"CD"stability"(eCbeam)"

Day 41

Shelf-Life >3 Months @ RT

Stored at room-temperature No systematic performance degradation observed over 15 weeks

Day 2 Day 15 Day 31 Day 106

18nm hp by EB

BMET EUV Imaging: YA Series

22nm hp

100 mJ/cm2 57 mJ/cm2

22nm hp

18nm hp 18nm hp

Dose reduced

40%

18nm dipole; Developer: n-BA Formulation & process optimization

PSI EUV Imaging: YA Series

Organic developer, 20nm FT, 150C PEB, dose: ~90 mJ/cm2 Unoptimized process

22nm hp 18nm hp 17nm hp

16nm hp 15nm hp 14nm hp

12nm hp

PSI EUV: TEM x-section of 22hp

Native SiO2

Pt layer for TEM

Si substrate

Inpria resist TEM x-section

New Platform Solves Key Challenges

Standard Developers

Path to required dose

Shelf stable and vacuum stable

High Developer Concentration

High Imaging Dose

Instability: shelf life and process

Image Fidelity (res & LWR)

Etch Resistance

High EUV absorbance

Image Fidelity (res & LWR)

Etch Resistance

High EUV absorbance

Gen 1 Gen 2

Ligand Selection Key Lever

~100x gain in radiolytic efficiency

Radiolytic efficiency modulated as predicted by chemistry of ligand sequence. Demonstrates control over an important component of improving sensitivity.

Liga

nd R

elat

ive

Con

cent

ratio

n*

Relative Exposure

Ligand 1

Ligand 2

Ligand 3

* Relative FTIR absorbance

Path to Improved Sensitivity

Standard Developers

Stability

ü Remove background condensation from development rate equation

•  High EUV absorbance, tunable M-L radiolysis platform to maximize or amplify photo-efficiency

•  Leverage strength of polarity change/solubility on oxide formation to limit threshold dose

Have stable, fab compatible platform: critical baseline for testing design modifications

Maximum Sensitivity

High Imaging

Dose

New Platform Solves Key Challenges

Standard Developers

Path to required dose

Shelf stable and vacuum stable

High Developer Concentration

High Imaging Dose

Instability: shelf life and process

Image Fidelity (res & LWR)

Etch Resistance

High EUV absorbance

Image Fidelity (res & LWR)

Etch Resistance

High EUV absorbance

Gen 1 Gen 2

Typical EUV Litho Module

•  Thick Spin On Carbon (SOC) often required for device stack •  Opening the SOC requires use of Si-HM (thickness/selectivity) •  Drives higher aspect ratio resist: can lead to pattern collapse

SOC

Si-HM

CA Resist

Simplified EUV Pattern Transfer

•  Process simplification –  Need <20nm of resist – mitigates pattern collapse –  Eliminates need for Si-HM: reduces coat/etch steps –  Allows higher SOC thickness

SOC

Inpria Resist

SOC

Si-HM

CA Resist

>38:1 selectivity to SOC using

O2:N2 open

Spin-On-Carbon Open

20 nm lines

High selectivity provides large process window for SOC open

20nm Inpria Resist

100nm SOC

EB expose, no hard bake O2:N2 etch

35 nm lines

Pattern Transfer & Resist Strip

O2:N2 (300W) C4F8:Ar (35W) After O2 (10W)

Resist consumed during etch

Inpria Resist 20nm

SOC 50nm

Si

Si etch SOC strip SOC open

Summary •  New metal oxide resist platform developed

–  High resolution (12nm hp by EB) –  Improved dose –  Stable –  Compatible with standard developers

•  High etch selectivity and pattern transfer demonstrated

•  Path identified to improved sensitivity and contrast

Acknowledgements

Thanks to our many partners, and also to the Inpria team

This material is based upon work supported by the National Science Foundation under SBIR Award Number 1026885