Richard – Page 25

Cleaning carbon from your optics

In EUV lithography, carbon deposition on the optics seriously degrades performance. A nice experiment at the University of Hyogo has shown that bleeding oxygen or ozone into the optics while irradiating with EUV can remove the deposits. [J. Vac. Sci. Technol. B 29, 011030 (2011); doi:10.1116/1.3533945]
An old invention by Somekh comes to mind; he discovered the same trick for electron beam systems in 1999. [US 6394109]

Earthquake and tsunami, Japan

To my friends and colleagues in Japan, I extend my deep sympathy to all those who suffer in the aftermath of this great earthquake.

– Richard L Lozes

Outsourcing

Reading this article in the LA Times today, I could not help but think of all the hollowed out semiconductor equipment companies in Silicon Valley. The SEMI heavyweights have been outsourcing for years, shedding ever more employees and expertise. Is it any wonder that there are no leading-edge vendors of lithography equipment in the U.S. anymore?

In a related vein, Gio Wiederhold (Stanford Univ.) details the process by which U.S. companies set up foreign subsidiaries strictly for the purpose of holding the company I.P. (patents, for example). Why? Simply to fluff up the finances and avoid U.S. taxes. (The paper is also available from Prof. Wiederhold’s home page.)

We can rest assured that all the hot air about job creation will come to naught until the rules of the game change.

Serendipitous update: See the just published article by Dominic Barton in Harvard Business Review on “Capitalism for the Long Term”.

EBL below 5 nm

The Lyding group at the University of Illinois at Urbana—Champaign reports the writing of < 5 nm metallic structures by EBL. The lithography was carried out by electron beam induced deposition of hafnium diboride in a UHV scanning tunneling microscope.

Find the publication at DOI: 10.1021/nn1018522 .

Single-electron pulses

In electron beam lithography, we usually attempt to squeeze as much current into the beam as possible. What about the other extreme? Can we arrange to get one electron at a time in the beam, and what use might that have?

The Baum group at the Max Planck Institute of Quantum Optics has done just this. Reporting in PNAS [doi: 10.1073/pnas.1010165107], they demonstrate single-electron pulses generated by photoemission. The photoemission in turn is driven by tuned, femtosecond UV pulses. Tuning of the UV wavelength turns out to be important for the bandwidth, coherence and duration of the resulting electron pulse. The experiment results in a transverse (electron) coherence of 2.5 nm, quite adequate for diffraction studies.

Now, with a coherence length of 2.5 nm and a duration of 100 fs or less, one can study atomic-scale dynamics in condensed matter and molecules by so-called four-dimensional imaging. Many interesting phenomena become visible; see the first twelve or so references in the paper.