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Practical selectivity window of selective epitaxial growth (SEG) using a H2/SiH4/Cl2 cyclic chemical vapor deposition (CVD) system has been investigated with the batch-type vertical furnace equipment, replacing a conventional single-wafer H2/dichlorosilane/HCl CVD system. The process temperature was less than 700 °C, which is suitable for a low thermal budget process applicable to next-generation memories including vertical pn-diode switches. Selectivity loss is quantified by an in-line inspection tool to determine the practical number of selectivity losses. The H2/SiH4/Cl2 cyclic CVD system provides an excellent capacity of 40 wafers per batch. Selectivity loss, which is one of the most crucial features in the SEG process for the diode application, is controlled with both the amount of SiH4 and Cl2 and the period of gas supply, and the practical number of selectivity loss is confirmed to be less than 100 in 200 mm wafers. Without high temperature annealing in hydrogen ambient, low temperature cyclic SEG in the batch reactor ensures the clean interface and improved crystalline quality of SEG-Si, as well as high throughput.

The contact resistance (R C) between a Ru electrode and a TiN plug in a crystalline Ta2O5 capacitor using Ru electrodes was evaluated. The TiN plug was oxidized in TiO x to increase the R C to failure. Two origins of oxygen are determined by Auger electron spectroscopy (AES) analysis, namely, the seed step of Ru deposition and the initial step of Ta2O5 deposition. During Ta2O5 crystallization annealing at 700°C, the oxygen molecules from Ru diffused into the TiN plug, forming TiO x . Ru films with Ti exhibited a decreased R C below 1 kΩ/contact and an increased leakage current of a Ru/Ta2O5/Ru capacitor according to the applied voltage, compared with Ru films without Ti. The atomic layer deposition (ALD) Ru process including a H2 plasma treatment decreased the R C to 2.5 kΩ/contact on average. The fabrication scheme for the crystalline Ta2O5 capacitor using the Ru electrode for reducing RC between the Ru storage node and the TiN plug was proposed.

Ru thin films were prepared by metalorganic chemical vapor deposition (MOCVD) using cyclopentadienyl-propylcyclopentadienlylruthenium(II) [RuCp(i-PrCp)] and the nucleation behaviors of Ru films on Ta2O5, TiN, Si3N4, SiO2, TiO2 substrates were investigated. It appeared that the difference in nucleation behaviors on various substrates is due to the bonding type between atoms in substrate materials. The nucleation property of Ru films on TiN was successfully improved by plasma treatment of the TiN substrate using Ar before film deposition. It was found that the Ar plasma treatment selectively removes N ions from the surface, makes the TiN surface more metallic or ionic (due to the residual Ti-O bonding), and reduces the nucleation barrier. In addition, the oxidation resistance of Ru/TiN layers was improved by H2 annealing, which made the Ru films more dense.