Sa-Kyun Rha

Structural and chemical stability of Ta–Si–N thin film between Si and Cu

Thermal stability and barrier performance of reactively sputter deposited Ta-Si-N thin films between Si and Cu were investigated. RF powers of Ta and Si targets were fixed and various N 2 /Ar flow ratios were adopted to change the amount of nitrogen in Ta-Si-N thin films. The structure of the films are amorphous and the resistivity increases with nitrogen content. After annealing of Si/Ta-Si-N(300 A)/Cu(1000 A) structures in Ar-H 2 (10%) ambient. sheet resistance measurement. X-ray diffraction (XRD). scanning electron microscopy (SEM). energy dispersive spectroscopy (EDS) and Auger electron spectroscopy (AES) were employed to characterize barrier performance. Cu 3 Si and tantalum silicide phase are formed at the same temperature. and the interdiffusion of Si and Cu occurs through the local defect sites. In all characterization techniques. nitrogen in the film appears to play an important role in thermal stability and resistance against Cu diffusion. A 300 A thick Ta 43 Si 4 N 53 barrier shows the excellent barrier property to suppress the formation of Cu 3 Si phase up to 800°C.

Adhesion and interface chemical reactions of Cu/polyimide and Cu/TiN by XPS

Abstract The chemical reaction at the interface between Cu and polyimide (PI) and between Cu and TiN at room temperature has been investigated using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). In case of Cu/TiN, there was no interface chemical reaction, but in case of Cu/PI system, there existed marked interface chemical reaction. From XPS core-level spectra, it was found that Cu atoms react mainly to oxygen and nitrogen in the PMDA (pyromellic-dianhybride) part of polyimide. Especially, the initial growth mode of Cu on polyimide was found by Cu LMM Auger spectra as follows; at first CuNO complex is formed, then CuOC complex formation by the weak interaction, and metallic Cu growth occurs simultaneously.

Improved TiN film as a diffusion barrier between copper and silicon

Abstract Reactively-sputtered TiN films were studied as a copper diffusion barrier in the Cu/TiN/Ti/Si and Cu/TiN/Ti/SiO2/Si multi-layer structures. From the viewpoint of the microstructure of TiN, the diffusion barrier property of TiN against copper improved when the grain boundary of TiN (as the diffusion path of copper) was extended and densified, which was confirmed by the increase of the breakdown temperature of the TiN diffusion barrier detected by various characterization methods. The 40-nm thick TiN with double deposition (extension of the grain boundary of TiN) and stuffing (the densification of the grain boundary of TiN) by RTP treatment (NH3, 600°C, 1 min) was found to be stable up to 575°C for 2 h by the C–V method.

Characterization of TiN barriers against Cu diffusion by capacitance–voltage measurement

Sputtered TiN was studied as a diffusion barrier in Cu/TiN/Ti/Si and Cu/TiN/Ti/SiO2/Si multilayer structures using various characterization methods, and their sensitivities for detecting breakdown of the barrier were compared. It was confirmed by scanning electron microscopy and Auger electron spectroscopy that breakdown of the TiN barrier occurred through out-diffusion of Si in addition to in-diffusion of Cu. Breakdown temperatures varied by more than 100 °C depending on characterization methods, and capacitance–voltage (C–V) measurement was most sensitive for detecting the failure of the TiN barrier. The effects of rapid thermal annealing (RTA) on barrier properties of TiN were investigated, and it was found by C–V measurement that the TiN(400 nm) RTA treated at 700 °C in a NH3 ambient was stable up to 590 °C for 2 h, while the reference TiN (400 nm) was stable up to 450 °C for 2 h.

Investigation of Silicon Oxide Thin Films Prepared by Atomic Layer Deposition Using SiH2Cl2 and O3 as the Precursors

Silicon dioxide thin films were deposited on p-type Si (100) substrates by atomic layer deposition (ALD) by alternating SiH2Cl2 and O3(1.5 at%)/O2 exposures at 300°C. O3 was generated by corona discharge inside the delivery line of O2. The oxide film was deposited mainly from O3, not from O2, because we could not observe the deposited film on the substrate without corona discharge under the same process condition. The growth rate of the deposited films increased linearly with increasing amount of simultaneous SiH2Cl2 and O3 exposures, and was saturated at approximately 0.35 nm/cycle with the reactant exposures of more than 3.6×109 L. A larger amount of O3/O2 than that of SiH2Cl2 was required to obtain a saturated deposition reaction. When the amount of O3/O2 exposure was varied at a fixed SiH2Cl2 exposure of 1.2×109 L, the growth rate of oxide film increased with O3 exposure and was saturated at approximately 0.28 nm/cycle with O3/O2 exposure of more than 2.4×109 L. The composition of the deposited film also varied with O3/O2 exposure. The Si/O ratio gradually decreased to 0.5 with increasing amount of O3/O2 exposure. Finally, we also compared the characteristics of the ALD films with those of the films deposited by conventional chemical vapor deposition (CVD) methods. The silicon oxide film prepared by the ALD method at 300°C showed stoichiometry, wet etch rate and average surface roughness comparable to those of the films deposited by low-pressure CVD (LPCVD) and atmospheric-pressure CVD (APCVD) at deposition temperatures ranging from 400 to 800°C

Atomic Layer Deposition of Silicon Oxide Thin Films by Alternating Exposures to Si2Cl6 and O3

We report the process for the atomic layer deposition (ALD) of silicon dioxide thin films on a silicon wafer by alternating exposures to Si 2 Cl 6 and O 3 . The deposition was governed by a self-limiting ALD reaction at 403-453°C, and the growth rate at 453°C was saturated at 0.32 nm/cycle for Si 2 Cl 6 exposures over 1 X 10 8 L. However, at 471°C or higher temperatures, the thermal decomposition of Si 2 Cl 6 and the oxidation of Si by O 3 dominated the deposition, resulting in high growth rates and Si-rich films. The ALD films exhibited excellent electrical properties that were equivalent to those of low-pressure chemical vapor deposition films.

Reflow of copper in an oxygen ambient

In order to investigate the reflow characteristics of copper, copper was deposited on hole and trench patterns by metal organic chemical vapor deposition and it was annealed in nitrogen and oxygen ambients with the annealing temperatures ranging from 350 to 550 °C. Upon annealing in an oxygen ambient at higher than 450 °C, copper was reflowed into the trench patterns whose line- width and aspect ratio were 0.2 μm and 4:1, respectively. Copper oxide was found with a thickness of less than a fifth of the total film thickness. The resistivity of the copper film increased when reflow occurred. It is thought that the reflow of copper in an oxygen ambient takes place because of enhanced surface diffusion.

Electrical Properties of Electroplated Cu Thin Film by Electrolyte Composite

The electrolyte effects of the electroplating solution in Cu films grown by ElectroPlating Deposition(EPD) were investigated. The electroplated Cu films were deposited on the Cu(20 nm)/Ti (20 nm)/p- type Si(100) substrate. Potentiostatic electrodeposition was carried out using three terminal methods: 1) an Ag/AgCl reference electrode, 2) a platinum plate as a counter electrode, and 3) a seed layer as a working electrode. In this study, we changed the concentration of a plating electrolyte that was composed of CuSO , H SO and HCl. The resistivity was measured with a four-point probe and the material properties were investigated by using XRD(X-ray Diffraction), an AFM(Atomic Force Microscope), a FE-SEM(Field Emission Scanning Electron Microscope) and an XPS(X-ray Photoelectron Spectroscopy).From the results, we concluded that the increase of the concentration of electrolytes led to the increase of the film density and the decrease of the electrical resistivity of the electroplated Cu film.

Atomic Layer Deposition and Properties of Silicon Oxide Thin Films Using Alternating Exposures to SiH2Cl2 and O3

We report the process for the atomic layer deposition (ALD) of silicon dioxide thin films on a silicon wafer by alternating exposures to SiH2Cl2 and O3. The growth kinetics of silicon oxide films was examined by varying reactant exposures at various deposition temperatures ranging from 250 to 450 °C. The deposition was governed by a self-limiting surface reaction, and the growth rate at 350 °C was saturated at 0.25 nm/cycle for SiH2Cl2 exposures of over 5×109 L (10-6 Torrs). The chlorine content and the wet-etching rate in a diluted HF solution were reduced by increasing the deposition temperature. The films deposited at temperatures ranging from 350 to 450 °C exhibited excellent physical and electrical properties that were equivalent to those of silicon oxide films deposited at 760 °C by low-pressure chemical vapor deposition.

Field‐Aided Thermal Chemical Vapor Deposition of Copper Using Cu(I) Organometallic Precursor

A dc substrate bias which is not enough to make a plasma was applied during the chemical vapor deposition of copper to change the adsorption behavior of the reactant. Copper films were deposited on TiN and Si02 from Cu(hfac)(tmvs) with and without the substrate bias. The surface morphology, the thickness, the sheet resistance, and the purity of the films were investigated. When a negative substrate bias of -30 V was applied to the substrate, the deposition rate of copper increased both on TiN and SiO 2 . The substrate bias did not cause the change in the chemical composition of the deposited copper film. It was calculated that Cu(hfac) has the dipole moment whose direction is from copper to hfac. The local electric fields due to surface roughness may affect the adsorption behavior of the precursor, especially the direction of the molecular dipole moment. Resulting from the overlapping population value analysis, the improvement of deposition rate under negative substrate bias was explained as due to the adsorption of the copper atom in the Cu(hfac) species directly onto the substrate by the local electric fields applied between the substrate and the gas showerhead.