The authors investigated the modified atomic layer deposition (ALD) of RuO2 films using bis(ethylcyclopentadienyl)ruthenium [Ru(EtCp)2] at a deposition temperature of 265°C. Oxygen gas diluted with argon was supplied throughout all of the ALD steps. The growth rate of the modified ALD RuO2 was about 1.4Å∕cycle, which is higher than that of conventional Ru ALD due to the increase in the amount of Ru(EtCp)2 adsorption per cycle, as well as the difference in the unit cell volumes of Ru and RuO2. The film thickness increased linearly with the number of cycles, and the incubation cycle in the initial stage was negligible.

The Pt hillock in a Pt/Ti electrode stack has been the main concern in ferroelectric random access memory due to the reliability problem. The origin of the hillock formation is the compressive stress, and the main mass transport mechanism for hillock formation is the grain boundary diffusion for thin films with a columnar structure. However, the hillock growth orientation and mechanism have not been reported. In this study, we found that an orientation relationship of Pt(100) hillock //Pt(111) thin film existed between the Pt hillock and the thin film. The Pt hillock was a single crystal having facets with polyatomic steps. From these results, we suggest that the Pt hillock growth mechanism is the layer growth of flat faces, which shapes the hillock into a tetrahedron single crystal. O 9 ͑SBT͒ thin films have many advantages when compared to Pb (Zr x Ti 1Ϫx )O 3 ͑PZT͒ thin films, such as being fatigue free, having a low leakage current, and having stable imprint characteristics for the application of ferroelectric random access memory ͑FeRAM͒. 1,2 In addition, Pt is chemically stable in a high processing temperature, which is necessary for crystallizing the ferroelectric oxide film. However, the adhesion of Pt to substrates such as silicon oxide (SiO x ) is poor. 3 Therefore, a Ti glue layer has, typically, been employed.The Pt/Ti electrode stack deposited by a sputtering method is likely to have a major instability problem in Pt hillock formation, which is reportedly the main cause of capacitor shorts. 4,5 The compressive stress generated in thin film is widely accepted as being responsible for the occurrence of hillocks in metallic thin film. 6,7 In the case of the Pt/Ti electrode stack, the Pt hillock formation is, reportedly, strongly dependent on the magnitude of the extrinsic compressive stress, which is generated by Ti diffusion into the Pt layer followed by oxidation in the Pt grain boundary during electrode annealing. 5 Accordingly, the Pt/TiO x electrode stack, which was substituted for a Ti glue layer, kept the Pt film surface flat, even when annealed at 650°C for 30 min in air atmosphere. 5 The main mass transport mechanism for the growth of the hillock on thin film with a columnar structure is the grain boundary diffusion. 8,9 Although the orientation relationship between the Pt hillock and Pt thin film has not been reported up to now because of the small hillock and the general lack of concern, it may be a critical clue for understanding the hillock growth mechanism. In this study, we found the orientation relationship between the Pt hillock and the thin film to be Pt(100) hillock //Pt(111) thin film , and we made a suggestion on the hillock growth mechanism.Both Pt and Ti films were sputter deposited on a ͗100͘oriented 8 in. silicon substrate, passivated with a thermally grown SiO x layer of 1000 Å thickness. The respective thicknesses of Pt and Ti were 2000 Å ͑sputtering rate 40 Å/s͒ and 200 Å ͑sputtering rate 10 Å/s͒. The details for the fabrication of the Pt/Ti electrode stack can be found in th...

The stress dependence of platinum hillock formation during post thermal cycling was investigated in Pt/Ti electrode stacks. Annealing temperatures were varied from room temperature (RT) to 650 • C. High compressive stress was generated during electrode annealing by the Ti diffusion into the platinum layer followed by oxidation in the platinum grain boundaries. The compressive stress was the major driving force for the hillock formation on the platinum surface. Thus, the Ti glue layer was oxidized before platinum deposition to reduce the Ti diffusion. The Pt/TiO x electrode stack retained its smooth platinum surface after the electrode annealing of 650 • C for 30 min in O 2. The Pt/TiO x interface remained flat even after the ferroelectric annealing at 800 • C, which was performed after SrBi 2 Ta 2 O 9 (SBT) deposition. Moreover, the remanent polarization (2P r) of the SBT capacitor was increased to 17 µC/cm 2 on the Pt/TiO x electrode stack, up from 13 µC/cm 2 , which was the value on the Pt/Ti electrode stack.

NewZrO 2 /Al 2 O 3 /ZrO 2 (ZAZ) dielectric film was theoretically designed and successfully demonstrated to be applicable to 45nm DRAM devices. ZAZ dielectric film is a combined structure from tetragonal ZrO 2 and amorphous Al 2 O 3 . Thus prepared ZAZ TIT capacitors showed very small Tox.eq value of 6.3Å and low leakage current less than 1fA/cell. It was also confirmed that ZAZ TIT capacitor was thermally robust during backend full thermal process by applying it to the final DRAM product in mass production.

1999) Intrinsic stress dependence of Pt hillock formation and its related electrical properties of SBT capacitor, The P f l i electrode stacks were deposited on the SiOxiSi substrate by DC magnetron sputtering. The Pt layers were deposited at various temperature of RT-500"C. These electrode stacks were annealed at 6 5 0 T for 30min in O2 ambient. A lot of high hillocks were observed on the Pt surface deposited at low temperatures (RT-300°C) after the anneal process. But the hillocks were decreased in both number and height with increasing the deposition temperature of the Pt layer. We found in both SEM inspection and stress measurement that the deposition temperature dependence of the Pt hillock formation could be explained by the difference in the intrinsic stress generated during deposition process. We also demonstrated the effect of Pt hillocks on electrical properties of SBT capacitor. The 2Pr values of the SBT capacitors were about 13p C/cm2 regardless of the Pt deposition temperatures. But the short probabilities were decreased with the increase of the Pt deposition temperatures. This result is well consistent with the trend of Pt hillock formation.