Tomorrow : 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

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 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
650-725-7075
-------------------------------------------------------

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

 

^aNanoscale 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@bham.ac.uk

^bSchool of Chemistry, The University of Birmingham, Birmingham, B15 2TT, UK

 

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/cm² 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.

[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.