The two pulses two wavelength driver of EUV radiation LPP source and of 4M Bragg mirror

objective for laboratory EUV Lithography tool:Development of the ISTC project #3857

R.Seisyan, A.Zhevlakov, M.Sasin

A.F.Ioffe Physical Technical Institute of Russian Academy of Sciences, St.-Petersburg, Russia

e-mail: rseis@ffm.ioffe.ru

ISTC project # 3857

“Key Technologies of EUV-nanolithography System of Super high Resolution on the Base of High Effective LPP Source”

February 2009 – February 2012

Project Budget – 317,501 € = $492,700

executors:Ioffe Institute

and

Institute for Laser Physics,

both Saint-Petersburg, Russia

Collaborators of the Project

1. Gerry O’Sullivan,

2. John Costello,

3. Torsten Feigl,

4. Peter Choi,

5. Ladislav Pina,

all COST MP0601 participants

ISTC project #3857,the first year Work Plan

1. Calculation and design of dual-wavelength (λ = 1.06 μm and λ = 10.6 μm) laser- optical scheme forming focal spot on the target at double-pulse illumination.

2. Calculation and design of 4-mirror wide-aperture imaging objective with enlarged image area.

3. Precise mechanical and optical systems development providing for nanometric scale precision for adjustment and focusing of nanolithographer optical system.

4. Placing of the optical and mechanical systems in existing body of NL tool, designed and partly manufactured in the frame of ISTC project #0991.

Experimental

nanolithographer

of Ioffe Institute

in the making

(2006)

View of the experimental hall with the dustless room (center and right) and prototype excimer laser (on the left) used in

the Experimental Stand work

The main ideas of the industrial EUV LPP source

• The main ideas used in the SYMER source (as well as in GIGAPHOTON source) are the following.

• Target material should be Sn (liquid Sn droplets)• The main primary laser should be pulsed

powerful (about 15-20kW) CO2 laser• The main ways to solve debris mitigation

problem are the use of magnetic field and • The use of inert gas curtain

Advanced LPP source for NL tool

Cross-section of string source

Collector

mirrorMagnets

String

target unit

The “String” EUV Source cross-section

To an object

ive, sampl

es, etc..

String

Capillary

String covered with tinGas pulse for debris mitigation

Ionised Tin, “cold” plasma

UV laser pulse

10μ laser pulse: heating

Hot, radiating EUV plasma

“String” EUV target with different laser wavelength ignition and heating

YAG:Nd+3 , 1064 nm

1.5 J, 8 ns, 10 Hz

Optical delay line, 1-200 ns

2-nd harmonic generator

Optical parametrical oscillator

H2 cell

CO2 laserObjective

10 m

Objective1064 nm

1064 nm

532 nm

1930 nm

10 m

Former design of dual-wavelength (λ = 1.06 μm and λ = 10.6 μm) laser-optical scheme forming focal spot on the target at double-

pulse illumination.

Resulting dual-wavelength (λ = 1.06 μm and λ = 10.6 μm) laser-optical scheme forming focal spot on the target at double-pulse

illumination

Calculation of CO2 laser driver

• Possible amplification of 6 pass CO2 laser driver (1ns initial pulse)

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.01

0.1

1

10

Эффективный радиус пучка, см

Энергия, Дж

1

2

3

4

Multipass scheme of CO2 amplifier

Multipass scheme for amplifier based on CO2 laser “Fialka”

1

2

L

Rm

Experimental Lithographer (EN) made in Ioffe Institute

EN optical scheme

LensCollector

Plasm

First Mirror

CorrectionMirror

Mask

Second Objective Mirror

First Objective Mirror

Sample

Screen

EUV Spectrograph

EUV Detector & Filter

12

33

.66

mm

99

.9

12

56

.2 m

m

Coupling system

Bragg mirror imaging systems with high resolution

NA=0,06 – 0,09

NA=0,1 – 0,14

NA=0,36

NA=0,485

Image modeling

L&S 30 nm, contrast 60%L&S 45 nm, contrast 97%

L&S 15 nm, contrast 58%

Four mirror objective

Results of mathematical modeling of

microstructures.

The image of corners with

width of a line 10 nm in the

centre of a field

The specification of the objective

The numerical aperture 0.485

The resolution 10 nm with contrast 0.26

20 nm with contrast 0.35

The sizes of the field of the image 0.27x0.27 mm2 → 2.0x2.0mm2

The central shielding 0.407

The distance from a mask up to a plane of the image 829 mm

Root mean square wave aberration on the field of the image

0.0573 - 0.1181

The limiting resolution 68000 mm with contrast 0.02

The magnification of the objective 12

27

Scheme of nanolithograph

LensCollector

Plasm

First Mirror

CorrectionMirror

Mask

Second Objective Mirror

First Objective Mirror

Sample

EUV Spectrograph

EUV Detector & Filter

Coupling system

Third Objective Mirror

Fourth Objective Mirror

Grating pattern must be such that suppress the second order of diffraction.

grating 1

grating 0

O

d

a

grating 1

grating 0

O

d

Lens

0 order0 order

incoming

beam

incoming

beam

+1 order

-1 order

Base unit

Principal scheme of focusing and alignment system

1

wafer surface

(reflective)

mask surface(grating 0)

Focus system with single grating and reflecting wafer(single canal)

a 0z

a0 0

фото-детекторb

фото-детекторa

b0 0

b 0

регуляторb

источник излучения

модулятор

фото-детекторa0

фото-детектор

b0

регуляторс памятьюa- b

O

Z

x

X

Axis of the grating is perpendicular to the drawing plane

Plane of incoming beams is normal to the drawing plane

plan

e of

out

put

beam

s

plan

e of

inco

min

g

diffr

acte

d be

ams

plan

e o

f

inco

min

g be

ams

2=V1

wafer surface

(reflective)

mask surface(grating 0)

X

x

Z

O

• An original technology for photomask production is developed in the Ioffe Institute for the EN. It includes originally invented mask pattern and construction, and technologies for deposition both reflecting and absorbing structures on the mask surface. The focusing and alignment systems represent by itself multichannel interferometers using gratings and second harmonics solid state laser projection device.

Scheme of the focusing system realization

Vibroprotective table

• The EN modules are installed on massive granite plate of vibroprotective table. The table has been invented in the Baltic University (St. Petersburg) and later finished off in conformity with the EN needs. The table has high performance characteristics and provides both passive and active vibroprotection including infralow frequencies.

Piezopositioners

Phenomenological modelof the non-linear photoresist

Exposure (mJ/cm )2

0.54

0.48

0.42

120600

2=4mJ/cmH

-E 2=2mJ/cm

c2J/cm3=8.510c2J/cm4=1.710thI

/J3cm-3C=310

H

-E

Initial condition

Boundary condition

101 t

)()( 00tItI

z

1 - 2 mJ/cm2, 2 - 4 mJ/cm2

Estimated parameters of inorganic nonlinear

photoresists

Sensitivity: C = 3×10-3 cm3/J,threshold intensity: Ith = 1.7×104 W/cm2,

threshold diffusion width: δ = 8.5×103 W/cm2.Dose of H = h/C = 1.7 mJ/cm2 is sufficient for exposure of

a photoresist specimen h=50-nm thick. Pulse threshold dose (at 20 ns) is Hth = τIth = 0.34 mJ/cm2.Thus, the necessary dose is accumulated with 5 pulses at the

threshold intensity and 20 ns pulse duration.

Computer simulation of the enhancement of the contrast by means of inorganic non-linear

photoresist

The contrast enhancement U=(r1/x)/b (at r=r1s, b=1/Ip(I/x)) dependence on illumination intensity

where Ip, Tp - intensity and time of pulseIth - threshold intensity - smearing of threshold intensity

0 1 2 3 41

2

I/Ith

The best quality of image is reachedunder conditions:

0.10.9

0.10.9

0

00.1

0.9

0.9

50

50

50

50

50

0

00.9

Ip th

Ip=2 Ith

Ip=0.5 Ith

Ip=1.5IthIp=0.25Ith

100 200 3000

IP

1

0

I0

0

0

x (nm)

Ip=0.25IthIp=0.25Ith

Ip=0.5IthIp=0.5Ith

Ip=0.803IthIp=0.803Ith

Ip=1.5IthIp=1.5Ith

Ip=2Ith

Experiments on the EUV exposure have been carried out with synchrotron 13.4nm emission and, in a tentative form, on the Experimental Stand, the auxiliary setup of the Ioffe Institute, for λ = (13.4 ± 0.3) nm.

• The results obtained suggest that the EUV sensitivity should be some lower than that at λ = 193 nm.

• As2S3 films exposed on the synchrotron, after the chemical development, demonstrated distinct interferention structure with 30-40 nm stripes and space-stripe period about 50-100 nm thereby confirming good resolution ability of the material.

QDC(quantum

dot crystal)Interference

transistorSingle-electron

transistor

QD semiconduct

or laser

Мезоскопические элементы

d

GRIN waveguide

n-clad

n-GaAs substrate

p-clad

p-contact

SQW active

d

GRIN waveguide

n-clad

n-GaAs substrate

p-clad

p-contact

SQW active

DFB Laser systems Mesoscopic elements Photon

crystals