comparison of cleaning methods for thin film surfaces
DESCRIPTION
Lena Johnson, Mitch Challis, Ross Robinson, Richard Sandberg Group 4 English 316 Oral Report June 16, 2003. Comparison of Cleaning Methods for Thin Film Surfaces. Applications for EUV Light Research. Multilayer Mirrors. EUV Lithography. EUV Astronomy. EUV Microscopes. - PowerPoint PPT PresentationTRANSCRIPT
Comparison of Cleaning Comparison of Cleaning Methods for Thin Film SurfacesMethods for Thin Film Surfaces
Lena Johnson, Mitch Challis, Ross Robinson, Lena Johnson, Mitch Challis, Ross Robinson, Richard SandbergRichard Sandberg
Group 4Group 4English 316 Oral ReportEnglish 316 Oral Report
June 16, 2003June 16, 2003
EUV Lithography
Images from www.schott.com/magazine/english/info99/
EUV AstronomyEUV Microscopes
www.lbl.gov/Science-Articles/Archive/xray-inside-cells.html
Applications for EUV Light ResearchMultilayer Mirrors
How small is that?How small is that? Want to reflect EUV (extreme Want to reflect EUV (extreme
ultraviolet) light (50-5 nm or 10ultraviolet) light (50-5 nm or 10-7 -7 cm)cm)
Image from http://imagers.gsfc.nasa.gov/ems/waves3.html
The ProblemThe Problem Organic contaminants collect on the Organic contaminants collect on the
surface (Junk).surface (Junk).– Interferes with measuring optical Interferes with measuring optical
constantsconstants
Example with visible lightExample with visible light
QuestionQuestion: : How do we effectively remove contaminants?How do we effectively remove contaminants?
OutlineOutline1.1. Measurement Measurement
methodsmethods2.2. Cleaning methods Cleaning methods
-Opticlean-Opticlean®®
-Plasma Etch-Plasma Etch-UV lamp-UV lamp
3.3. ConclusionsConclusions
Video Video Measurement methodMeasurement method
– EllipsometryEllipsometry
Cleaning methods testedCleaning methods tested– OpticleanOpticlean– UV LampUV Lamp– Plasma EtchPlasma Etch
450
14318 16
0
50
100
150
200
250
300
350
400
450
Add
ition
al T
hick
ness
(Ǻ
)
1
Short Exposure Contamination Experiment (10 sec)
Spit onTouched with bare fingers (10s)Dipped in Deionized W aterTouched and rubbed with latex glove (10s)
OpticleanOpticlean®® Process leaves Process leaves hydrocarbon residuehydrocarbon residue
• Opticlean® significantly removes contaminants, but leaves a residue
• Ellipsometric ResultsOpticlean® residuethickness on two runs:1) 17 Ångstroms2) 22 Ångstroms
• Opticlean® made by Dantronix Research and Technologies, LLC
• Ellipsometer Type: J.A. Woollam Co., Inc Multi-Wavelength Ellipsometer (EC110)
http://www.dantronix.com
http://www.jawoollam.com/
Does the OpticleanDoes the Opticlean®®
process damage process damage thin films?thin films?
Scanning Electron Scanning Electron Microscope showed no thin Microscope showed no thin film damage, nor trace of film damage, nor trace of materials used in thin films materials used in thin films on pulled of on pulled of OpticleanOpticlean® ®
films (U, Sc, Va).films (U, Sc, Va).
X-Ray Photoelectron X-Ray Photoelectron Spectroscopy found no Spectroscopy found no trace of materials used in trace of materials used in thin films on pulled of thin films on pulled of OpticleanOpticlean® ® ..
XPS revealed components of OpticleanOpticlean®®, but not heavier metals used in thin films.
Prominent thin-film lines: U-380 eV, V-515 eV, Sc-400 eV
Photon Energy (eV)
Pho
tons
(Cou
nts)
97 eV (Si 2p)
148 eV (Si 2s)
281 eV (C 1s)527 eV (O 1s)684 eV (F 1s)
Cleaning residue with “Matrix” Cleaning residue with “Matrix” Plasma EtchPlasma Etch
RF Plasma Etching with ORF Plasma Etching with O2 2 PlasmaPlasma– 0.120 Torr Pressure0.120 Torr Pressure– 250W RF (max 350)250W RF (max 350)– 0.75 SCCM O0.75 SCCM O22 flow flow– No extra heat appliedNo extra heat applied
Good for removing Good for removing polymers, but not bulk polymers, but not bulk contaminants (i.e. Dust)contaminants (i.e. Dust)
Oxygen plasma plus Oxygen plasma plus mechanical sputtering mechanical sputtering removes surface layersremoves surface layers
RF
Plasma ResultsPlasma ResultsMatrix System
-12
-10
-8
-6
-4
-2
0
2
0 2 4 6 8 10 12 14 16 18
Minutes In Plasma
Cha
nge
in th
ickn
ess
(Å)
UV Lamp UV Lamp
UV ResultsUV Results
UV Lamp
-8
-6
-4
-2
0
2
0 5 10 15 20 25
Time Under UV Lamp (s)
Cha
nge
in
Thic
knes
s (
Ǻ)
ConclusionConclusion
Recommended Procedure:Recommended Procedure:– UV lamp for 5 minutesUV lamp for 5 minutes
Method Effectiveness Cleaning Time Ease of Use Notes
Opticlean® Left residue Must wait for polymer to cure
Can be difficult to peel off.
Good for dust etc..
Oxygen Plasma Effective. Cl not completely removed
Setup takes a few minutes. Clean under a minute
Equipment in clean room. Complex to
setup.
Builds up silicon dioxide
Eximer UV Lamp Effective 1 to 5 minutes Very easy Less silicon dioxide
buildup then plasma.
Opticlean® + Oxygen Plasma
Effective Possible 1 Å residue or oxide
Long, plasma setup and polymer
cure time.
Complex clean room equipment
and skill needed to peel
ConclusionConclusion
Recommended Procedure:Recommended Procedure:– UV lamp for 5 minutesUV lamp for 5 minutes
Method Effectiveness Cleaning Time Ease of Use Notes
Opticlean® Left residue Must wait for polymer to cure
Can be difficult to peel off.
Good for dust etc..
Oxygen Plasma Effective. Cl not completely removed
Setup takes a few minutes. Clean under a minute
Equipment in clean room. Complex to
setup.
Builds up silicon dioxide
Eximer UV Lamp Effective 1 to 5 minutes Very easy Less silicon dioxide
buildup then plasma.
Opticlean® + Oxygen Plasma
Effective Possible 1 Å residue or oxide
Long, plasma setup and polymer
cure time.
Complex clean room equipment
and skill needed to peel