Area-Selective Atomic Layer Deposition of ZnO on Si\SiO 2 Modified with Tris(dimethylamino)methylsilane.

Delayed atomic layer deposition (ALD) of ZnO, i.e., area selective (AS)-ALD, was successfully achieved on silicon wafers (Si\SiO 2 ) terminated with tris(dimethylamino)methylsilane (TDMAMS). This resist molecule was deposited in a home-built, near-atmospheric pressure, flow-through, gas-phase reactor. TDMAMS had previously been shown to react with Si\SiO 2 in a single cycle/reaction and to drastically reduce the number of silanols that remain at the surface. ZnO was deposited in a commercial ALD system using dimethylzinc (DMZ) as the zinc precursor and H 2 O as the coreactant. Deposition of TDMAMS was confirmed by spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), and wetting. ALD of ZnO, including its selectivity on TDMAMS-terminated Si\SiO 2 (Si\SiO 2 \TDMAMS), was confirmed by in situ multi-wavelength ellipsometry, ex situ SE, XPS, and/or high-sensitivity/low-energy ion scattering (HS-LEIS). The thermal stability of the TDMAMS resist layer, which is an important parameter for AS-ALD, was investigated by heating Si\SiO 2 \TDMAMS in air and nitrogen at 330 °C. ALD of ZnO takes place more readily on Si\SiO 2 \TDMAMS heated in the air than in N 2 , suggesting greater damage to the surface heated in the air. To better understand the in situ ALD of ZnO on Si\SiO 2 \TDMAMS and modified (thermally stressed) forms of it, the ellipsometry results were plotted as the normalized growth per cycle. Even one short pulse of TDMAMS effectively passivates Si\SiO 2 . TDMAMS can be a useful, small-molecule inhibitor of ALD of ZnO on Si\SiO 2 surfaces.