Diffusion barrier materials, TiN and WN, were deposited by atomic layer deposition (ALD). The chlorine concentration of the TiN film was as low as 1.2 at.-%, and resistivity was below 200 lX cm. Ultra high aspect ratio (AR = 85) trenches were used to assess step coverage. Tungsten nitride film, deposited from WF 6 and ammonia, was found to have high resistivity, although the residue content was low. The barrier deposition compatibility was studied using the copper surface exposed on the bottom of vias in the copper dual-damascene structure. The deposition on copper of both TiN and WN was found to be very challenging.
Ca 3 (thd) 6 ] (thd ) 2,2,6,6-tetramethyl-3,5-heptanedionato) dissolved in hexane and in the presence of tetraethylenepentamine (tetraen) crystallizes as a 1:1 [Ca(thd) 2 (tetraen)] adduct complex in the orthorhombic Pccn space group with a ) 10.874(2) Å, b ) 15.480(3) Å, c ) 20.866(4) Å, and Z ) 4. The molecule is monomeric with an 8-coordinated calcium atom. The adduct complex volatilized at lower temperature than the nonadducted complex. [Ca-(thd) 2 (tetraen)] can be utilized as a precursor in growth CaS thin films by the atomic layer epitaxy method. The growth rate with [Ca(thd) 2 (tetraen)] is lower (0.43 Å/cycle) than that with [Ca 3 (thd) 6 ] (0.50 Å/cycle).
BaS and BaS:Ce thin films were grown by Atomic Layer Epitaxy (ALE) from Ba(thd) 2 synthesized in situ during the film growth process by a gas-solid reaction between Hthd and Ba(OH) 2 . The in situ synthesis avoids problems related to aging of Ba(thd) 2 solid source when heated for prolonged times in normal ALE or CVD processes. H 2 S was used as a sulfur source. Self-limiting film growth with a rate of about 0.8 Å/cycle was obtained between 300 and 350°C. The films were polycrystalline and strongly oriented in the (100) direction. BaS:Ce films were deposited using Ce(thd) 4 as a dopant source. In photoluminescence these films gave a broad emission spectrum centered around 525 nm. Electroluminescence measurements gave C.I.E. color coordinates x = 0.46 and y = 0.50.Keywords: Barium sulfide, Cerium, Atomic layer epitaxy, Thin films, Electroluminescence Recently Soininen et al. [25,26] introduced a novel method for synthesizing a related compound (Sr(thd) 2 ) n in situ during an ALE process. The in situ synthesis was realized by volatilizing the liquid Hthd ligand under a reduced pressure inside the ALE reactor and leading the vapor over a
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