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DS: Fachverband Dünne Schichten

DS 49: Atomic Layer Deposition

DS 49.1: Hauptvortrag

Freitag, 4. April 2014, 09:30–10:00, CHE 91

Synthesis, Characterization, and Application of Tunable Resistance Coatings — •Jeffrey W. Elam — Argonne National Laboratory, Argonne, IL, USA

We used atomic layer deposition (ALD) to synthesize nanocomposite coatings comprised of M:Al2O3 where M= W or Mo using alternating exposures to trimethyl aluminum (TMA) and H2O for the Al2O3 ALD and alternating MF6/Si2H6 exposures for the metal ALD. By varying the ratio of metal and the Al2O3 ALD cycles, we can tune precisely the resistance of these coatings over a very broad range from 1012-105 Ohm-cm. These films exhibit Ohmic behavior and resist breakdown even at high electric fields of 107 V/m. Moreover, the self-limiting nature of ALD allows us to grow these films inside of porous substrates and on complex, 3D surfaces. To investigate the growth mechanism we employed in situ QCM and FTIR absorption spectroscopy studies. For the Mo:Al2O3 films, QCM showed that the Mo ALD inhibits the Al2O3 ALD and vice versa. Surprisingly, FTIR revealed that the reducing agent for the Mo is not the Si2H6, but rather the TMA exposure from the subsequent Al2O3 ALD cycle. Cross sectional TEM revealed the film structure to be metallic nanoparticles (~1 nm) embedded in an amorphous matrix. We utilized these coatings to fabricate large-area microchannel plates for large-area photodetectors, and as charge drain coatings in MEMS devices for a prototype electron beam lithography tool.