Special Ebeam Lab Presentation: Chemically Amplified Molecular Resists for E-Beam Lithography , Dr. Alex Robinson University of Birmingham, UK. Tuesday March 4 , 20081:30 PM CIS 101

James Conway jwc at snf.stanford.edu
Fri Feb 29 11:24:39 PST 2008

*Special Ebeam Lab Presentation: 
Chemically Amplified Molecular Resists for E-Beam Lithography
Dr. Alex P.G. Robinson University of Birmingham, UK.
Tuesday March 4, 2008 1:30 PM in CIS 101*

*It is my pleasure to announce that Dr. Alex P.G. Robinson will be 
visiting the Stanford Nanofabrication Facility next Tuesday afternoon 
and will present his work on Chemically Amplified Molecular Resists. He 
has also promised to give us an introduction and an update on activities 
at the Nanoscale Physics Research Laboratory <http://nprl.bham.ac.uk/> 
at the **University of Birmingham.

All interested parties are invited to attend.  There will be ample time 
for discussions after his presentation and we have the room through 3 PM.

James W. Conway
Ebeam Lab
Stanford Nanofabrication Facility


*Chemically Amplified Molecular Resists for E-Beam Lithography***

J. Manyam^a , F.P. Gibbons^a , S. Diegoli^b , M. Manickam^b , J.A. 
Preece^b , R.E. Palmer^a , _A.P.G. Robinson_^a

/ /

^a Nanoscale Physics Research Laboratory, School of Physics and 
Astronomy, The University of Birmingham, Birmingham, B15 2TT, UK

phone: +44 (0)121 414 4641   e-mail: a.p.g.robinson at bham.ac.uk 
<mailto:alex at nprl.ph.bham.ac.uk>

^b School of Chemistry, The University of Birmingham, Birmingham, B15 


Key words:  Electron Beam Lithography, Molecular Resist, Fullerene, 
Chemically Amplified Resist


The minimum lithographic feature size for microelectronic fabrication 
continues to shrink, and resist properties are beginning to dominate the 
achievable resolution. There is a strong need for a high resolution, 
high sensitivity resist for the 32 nm node, and beyond, that is not met 
by conventional polymeric resists at this time. The line width roughness 
(LWR) requirements at the 32 nm node [1] are already equal to the radius 
of gyration of a typical resist polymer, [2] whilst the resolution 
itself will be less than the polymer molecule size at future nodes. 
Molecular resists, such as oglimers and molecular glasses rely on 
smaller molecules, giving the potential for lower LWR and improved 
resolution. Fullerene derivative molecules have a diameter of 
approximately 1 nm and have been shown to act as negative tone resists 
with high etch durability and a resolution of 10 nm when exposed via 
electron beam lithography.  However, the sensitivity of such resists is 
extremely poor and significant improvements would have to be made to 
make the material commercially viable.  A common way to improve resist 
sensitivity is chemical amplification (CA) by addition of a 
photosensitizer, and optionally a cross-linker. Here we present a 
fullerene based three component chemically amplified resist system, 
which shows high resolution and sensitivity, wide process latitude, and 
etch durability comparable with commercial novolac resists.


Fullerene resist films were prepared on hydrogen terminated silicon by 
spin coating and were irradiated using a Philips XL30SFEG scanning 
electron microscope equipped with a Raith lithography system. The 
fullerene CA resist consisted of the derivative MF03-04, an epoxide 
cross-linker and a photoacid generator.  The sensitivity of this resist 
was shown to be between 5 and 10 µC/cm^2 at 20 keV for various 
combinations of post application bake and post exposure bake 
conditions.  Using 30 keV electron beam exposure, sparse patterns with 
12 nm resolution were demonstrated, at a line dose of 300 pC/cm, whilst 
dense patterns with half-pitch 20 nm were achieved at 200 pC/cm, as 
shown in figure 1. The LWR for the densely patterned resist (measured at 
hp 25 nm) is approximately 4 nm. The etch durability of the fullerene 
resist was comparable to SAL601, a common novolac resist.


[1] International Technology Road map for Semiconductors, 2006 Update, 
http://www.itrs.net <http://www.itrs.net/>.

[2] R.L. Brainard, G.G. Barclay, E.H. Anderson, L.E. Ocola, 
Microelectron. Eng., *2002*, /61-62/, 707.


Figure 1:         20 nm half-pitch lines and spaces exposed with a dose 
of 200 pC/cm at 30 keV, developed in MCB (1:1) IPA for 10 s, with a 10 s 
IPA rinse.








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