A potentially manufacturable liquid source metalorganic chemical vapor deposition process was successfully applied to deposit Iridium films on a variety of substrates. The depositions of Ir were carried out in the temperature range of 300–450°C from tetrahydrofuran (THF) solution of CH3CpIrCOD (Cp=cyclopentadienyl, COD=cyclooctadiene) in a low-pressure, hot-wall reactor. Oxygen assisted pyrolysis of the precursor at 350°C resulted in a remarkably high Ir growth rate of 70 nm/min on IrO x /Si substrate. Additionally, Ir on Si exhibited a room-temperature resistivity of 10.2 µΩ cm. The as-deposited polycrystalline Ir films were highly reflecting, dense, and fine grained.

Highly (111)-oriented and conformal iridium (Ir) films were deposited by a liquid source metalorganic-chemical-vapor-deposition process on various substrates. An oxygen-assisted pyrolysis of (methylcyclopentadienyl) (1,5-cyclooctadiene) Ir precursor at a wide range of substrate temperatures (Tsub) between 300 and 700 °C was used. At a low Tsub of 350 °C, the randomly oriented polycrystalline films exhibited an I111/I200 x-ray intensity ratio of 6. However, the films deposited at Tsub = 700 °C on native SiO2 and amorphous SiO2 surfaces were highly oriented with the I111/I200 ratios of 277 and 186, respectively. The transmission electron microscopy study revealed continuous, dense, and faceted microstructures of Ir films. Also, the step coverage of Ir on TiN (64%) was higher than that on amorphous SiO2 (50%) surfaces.

Downscaling of CMOS gate stacks requires introduction of ultra-thin high-k dielectrics such as HfO2. Atomic Layer Deposition has excellent characteristics for depositing such films. We have compared HfCl4/H2O and TEMAH/O3 ALD between 245ºC and 370ºC. Growth behavior and electrical performance are discussed as function of process parameters. Precursor choice has a clear impact on HfO2 deposition process and device performance. Both precursors demonstrate good growth nucleation on -OH rich starting surfaces. TEMAH shows better nucleation on low -OH density surfaces, suggesting a potential advantage for interface optimization towards low EOT. However, with HfCl4 lowest leakage currents were obtained as well as excellent interface scaling results by using well chosen interface layers. The leakage current of TEMAH/O3 layers strongly depends on the ALD process temperature and oxidizer dose, suggesting the impact of C impurities on the dielectric properties. Overall the HfCl4 approach seems to be the most promising solution.

The electrical performance of hafnium silicate (HfSiO x ) gate stacks grown by atomic layer deposition (ALD) has been evaluated in capacitors and transistors. First, scaling potential of HfSiO x layers was studied as function of composition and thickness. It is shown that the equivalent oxide thickness scales down with decreasing layer thickness and increasing Hfcontent. The gate leakage (at V fb -1V), however, is mainly determined by the physical layer thickness. For the same equivalent oxide thickness (EOT) target, the lowest leakage is observed for the layers with the highest Hf-content. Leakage values as low as 1x10 -3 A/cm 2 for an equivalent oxide thickness of 1.3 nm have been obtained. Second, the thermal stability against crystallization of the ALD HfSiO x has been studied and related to their electrical properties. The thermal stability of HfSiO x decreases with increasing Hf-content that necessitates the use of nitridation. The influence of various annealing conditions on the nitrogen incorporation is also studied. Finally, the effect of HfSiO x composition and postdeposition nitridation is discussed on transistor level. TaN metal gate transistor data indicate that nitridation reduces the gate leakage and that Hf-rich HfSiO x layers show the best scaling potential, i.e., highest performance for the lowest gate leakage.

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