Hi Professors Moses and Schulz,

I'm at the University of Illinois at Urbana-Champaign working toward my Ph. D. in materials science and engineering. I decided that electronic materials was a very interesting subfield of materials science, and joined a group that does low-pressure chemical vapor deposition (CVD). Since this involves both chemistry and physics, it lets me use both my physics and chemistry backgrounds. It was a good way not to have to choose between the two.

After taking some undergraduate engineering classes, I passed my quals on the first try at the end of my first year. (In retrospect, I overstudied the physics immensely. Images of Professor Moses and Professor Schulz looking at me disapprovingly and of Professor Schneider telling me I should have learnt this in prenatal care made me ready to derive band theory from scratch, but it turns out engineering professors don't care. Well, at least I was ready had they asked!)

I'm working on deposition of ruthenium, which is of interest for components in microelectronics like DRAM capacitors, metal gates in p-MOSFETs and as an electroplating seed layer in the copper dual damascene process for interconnects at the 31-nm node. I gave a talk at the spring Materials Research Society meeting that was very well-received, and just heard that my conference proceedings paper was accepted for publication, so I'm about to have my first paper published! (Gossip at the meeting actually suggests to me that Intel's new chip with metal/high-k dielectric stacks uses ruthenium for the p-MOSFET metal gates, and they may have bought a process from Micron that uses my molecule. As it turns out, Micron has been using my molecule for a long time, but have not published anything in the academic literature.)

We collaborate with a chemistry group that develops new molecules that should work well for CVD, and my molecule is indeed working very well. (I even got to synthesize it myself!) It decomposes thermally at low temperatures and the films are of excellent quality. (Micrograph attached.) What's remarkable about these films is how compact they are. Often, thin films of materials grown in columns that almost don't touch. Rather than being like a sheet, they are more like a forest of trees. All of my films are sheetlike, and they conduct very well, probably in large part because of this. It goes without saying that a conductor full of gaps doesn't conduct as well as it could.

Ultimately, I want to understand the film growth mechanisms. That gets a fun spin from that ruthenium is catalytic, so there may be reaction pathways possible that are not considered in the canonical theories for how films grow. For example, it may be that different crystal faces of ruthenium catalyze the decomposition of the molecule better than others, resulting in that grains oriented a certain way grow faster because they autocatalyze their own growth. The canonical view is that certain grains grow larger than others because they grow laterally faster than others purely due to geometry and then 'crowd out' the grains that don't grow upward as fast. Our vacuum chamber has a number of nice in-situ analytical tools that should help in figuring out the film growth mechanisms. If anyone needs something coated in ruthenium, you know who to call!

Nice seeing you guys again!

Tess

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Teresa Lazarz
Ph. D. Candidate in Thin Film Deposition
Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign