Masayuki Asai

Electrical and physical properties of HfO2 films prepared by remote plasma oxidation of Hf metal

The electrical and physical properties of thin hafnium oxide (HfO2) films fabricated by a remote plasma oxidation of a hafnium metal were investigated. The HfO2 capacitors with TiN electrodes exhibited excellent electrical characteristics such as equivalent oxide thickness (EOT) of 0.65 nm with leakage current density of 2.7 A/cm2 at the gate bias of Vfb-1 (V). The HfO2 thickness dependence of the EOT demonstrated that the permittivity of 19 for HfO2 layer and the interfacial layer thickness of 0.36 nm. X-ray photoelectron spectroscopy study revealed that the oxygen radicals oxidize the Hf metal selectively than Si substrate, leading to an increase of permittivity of HfO2 with reduced interfacial layer growth.

Metalorganic Chemical Vapor Deposition of HfO2 Films through the Alternating Supply of Tetrakis(1-methoxy-2-methyl-2-propoxy)-Hafnium and Remote-Plasma Oxygen

Thin films of hafnium oxide were deposited by sequence in which the supply of tetrakis (1-methoxy-2-methyl-2-propoxy)-hafnium and remote-plasma oxygen were alternated. Increasing the number of cycles of alternating supply led to decreased amounts of hydrocarbon impurities in the film and the realization of an amorphous characteristic for the as-deposited films. HfO2 dielectric capacitors produced by using this alternating supply technique exhibit values for leakage current that are two orders of magnitude lower than those of capacitors produced using the conventional process of metalorganic chemical vapor deposition. This effective improvement can be explained by the reduced presence of impurities, particularly H2O.

Impact of Hf Metal Predeposition on the Properties of HfO2 Grown by Physical and Chemical Vapor Deposition

Electrical and microstructural properties of a hafnium oxide (HfO2) grown by physical vapor deposition (PVD) and chemical vapor deposition (CVD) onto a predeposited hafnium metal (Hf) are investigated. In PVD in an Ar/O2 plasma atmosphere, energetic oxygen species oxidize the Si substrate through HfO2, generating a thick interfacial layer between the HfO2 and Si substrates. The interfacial layer, however, is found to be controllable to have a minimum equivalent oxide thickness (EOT) and lower leakage current by the predeposition of Hf metal due to the blocking of oxygen diffusion into the Si substrate by the oxidation of Hf metal itself. In addition to the oxygen blocking, the CVD-grown HfO2 films on the predeposited Hf metal layer are improved due to the easy dissociation of the Hf precursor on the metallic Hf layer with a shorter incubation time. The leakage current with the predeposited Hf metal is two orders of magnitude lower than that on the Si substrate, whereas the EOT and the interfacial layer thickness are invariant.

Metal-Organic Chemical Vapor Deposition of HfO2 by Alternating Supply of Tetrakis-Diethylamino-Hafnium and Remote-Plasma Oxygen

HfO2 films were fabricated through an alternating supply process, which consisted of deposition using tetrakis-diethylamino-hafnium (TDEAHf:Hf(N(C2H5)2)4), followed by oxidation using remote-plasma oxygen (RPO). Deposition rates were found to depend on temperature (above 350°C) and the supply duration of TDEAHf, which indicated a non-self-limiting growth mode. X-ray photoelectron spectroscopy (XPS) analysis revealed that as-deposited films fabricated by supplying only TDEAHf were unstable with the presence of carbon and nitrogen impurities, but these can be removed by supplying RPO. Sufficient supply durations of RPO produced stoichiometric HfO2 films accompanied by an efficient reduction in the leakage current of the films, but an excess RPO supply duration resulted in a larger equivalent oxide thickness (EOT) due to a decrease in the permittivity of the interfacial layer. By optimizing the supply durations of TDEAHf and RPO, a minimal EOT of 1.6 nm and a leakage current of 1×10-4 A/cm2 at -1 V relative to the flat-band voltage were achieved.

Growth and effects of remote-plasma oxidation on thin films of HfO2 prepared by metal-organic chemical-vapor deposition

The metal-organic (MO) chemical vapor deposition of hafnium oxide (HfO2) films from a new MO precursor, Hf(OC(CH3)2CH2OCH3)4, was investigated. The deposition rate of HfO2 is higher when oxygen gas is being supplied with the precursor. However, films deposited in the presence of added oxygen contain large amounts of H2O due to oxidation of the Hf precursor. O2 addition process degraded HfO2 film properties. In situ remote-plasma oxidation (RPO) is found to be effective in reducing the contaminants in HfO2. Leakage current in HfO2/Si capacitors with TiN gate electrode is also shown to be lower when deposition is without the oxygen addition and RPO treatment is subsequently performed.

High-Quality HfO2 Formation using Zr Reduced High-Purity TEMAH

HfO 2 films have been grown by an atomic layer deposition method using a high-purity tetrakis(ethylmethylamido)hafnium (TEMAH). TEMAH, which has been used as a source material for HfO 2 film formation, is likely to include zirconium (Zr) or titanium (Ti) atoms as impurities in the manufacturing process, and further purification was difficult. We succeeded in synthesizing a high-purity TEMAH with a reduced Zr concentration of impurities. The electrical properties of HfO 2 films were investigated, and the breakdown voltage and leakage current were improved by decreasing Zr impurities.

Impact of Hf metal pre-deposition in CVD- and PVD-HfO2 dielectrics

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Manufacturing method of semiconductor device and substrate processing apparatus

_tign annealing @Oe; -is required ro deniify CVD_-HfO_2 rgmo_ying impurifies (Cl, hydrogen, carboir gd.H2O)I3,4l.CVD growth in oxidizihg a-mbient and PDA process cause the thick interfacial-laver qrowth. Althqgg! P_VD-HfO2 is no conraminated witfi im[urities

Method for manufacturing semiconductor device, and substrate processing apparatus

t qVD-HfO2, energetic species are likely to redct with

Semiconductor device producing method

s-ubslrates, leading to a thick interfaciil layer t5-81. Both_ deposition techniques will make tirc thici( interfacial lay-ers with low permittivity, leading to increase an effective oxide thiikness. tn iiris papei, we will demonstrate the EOT reduction of CVDand PVD-HfO2 capacitors with acceptable lower leakage current by means of pre-deposition of Hf metal layer.