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Particle generation by gas-phase nucleation in the plasma enhanced chemical vapor deposition process and its effects on thin film surface morphology were studied experimentally for a conventional radio frequency plasma reactor using tetraethylorthosilicate (TEOS) vapor and oxygen gases. The particles suspended in the plasma space and deposited on the film were observed simultaneously by in situ laser light scattering methods and an ex situ scanning electron microscopic method. The generated particles were trapped in the plasma/sheath boundary under all four experimental conditions, in which TEOS concentrations were 0.5 and 5.0 vol % and reactor pressures were 66.7 and 533.3 Pa (0.5 and 4.0 Torr). The size and amount of particles and the film morphology were found to depend on the TEOS concentration and the reactor pressure. Under the conditions in which highly concentrated particles were generated in plasma, dome-like structures of 50–400 nm in diameter were observed on the thin film surface. The average size of the dome-like structure was comparable to that of the particles generated in plasma.

An ultrahigh vacuum sputtering system with offset incidence magnetron sources has been designed and developed to deposit thin films and multilayers with excellent film thickness uniformity, precise control over layer thickness, and surface and interface roughness. The unique feature of the system is that the sputtering guns are aligned at 35° oblique incidence onto a rotating substrate with a 60 mm offset from the substrate center, which make full use of the best linearity of the plasma flux at the substrate, and therefore, deposit extremely uniform thin films. Other features include, computer-controlled deposition process, capability of heating the substrate to 1100 °C, and in situ monitoring of thin-film quality with reflection high-energy electron diffraction. The performance of the sputtering system is demonstrated, and a characterization of multilayers deposited by the system using a grazing incidence x-ray reflectivity and high resolution electron microscope is also presented.

In order to analyze the particle generation and its effect on the SiO2 thin film in an atmospheric pressure chemical vapor deposition (APCVD) process using four organic silicon vapors and ozone gas, gas-phase particle generation, growth, transportation and vapor-cluster/particle codeposition processes were studied experimentally and theoretically using a flow-type vertical tube reactor. Decomposition reaction rates of four organic silicon vapors (tetraethylorthosilicate, triethoxysilane, tetramethylorthosilicate, and octamethylcyclotetrasiloxane) due to the O⋅oxidation were determined by arranging the number concentrations of the generated particles in Arrhenius plots. The obtained activation energies and frequency factors of reaction rate constants were used to simulate the vapor-cluster/particle codeposition in the CVD process. In the numerical simulation, computational fluid dynamics equations (continuity, momentum, and energy conservation equations) were solved to evaluate the gas velocity, vapor conc...

Amorphous/nanopolycrystalline Si3N4/TiN nanostructured multilayer films have been fabricated by radio-frequency reactive magnetron sputtering. The effects of deposition temperature, modulation period, and the layer thickness ratio on the hardness have been studied, in order to elucidate the hardening mechanisms in these multilayers. The hardness of the Si3N4/TiN multilayers is affected not only by the modulation periods, but also by the layer thickness ratio and deposition temperature. The hardness value is about 40% higher than the value calculated from the rule of mixtures at a deposition temperature of 500 °C and a modulation ratio (lSi3N4/lTiN) of 3/1. Based on the experimental results, it is suggested that the alternating stress field caused by thermal mismatch between Si3N4 and TiN is one of the main reasons for the superhardness effect in Si3N4/TiN nanostructured multilayers.

A chemical vapor deposition (CVD) method, called ionization CVD, in which ionized source molecules were deposited on a substrate by Coulombic force, was developed to control gas-phase reaction and film morphology. This method was applied to the tetraethylorthosilicate (TEOS)/ozone-atmospheric pressure chemical vapor deposition process by using the surface corona discharge. TEOS/O3 films deposited on SiN and SiO2 films by this CVD method showed good properties for the flow shape, the gap filling and the surface morphology. In Fourier-transform infrared spectra of gas-phase intermediates collected in the vapor condenser, the intensity of the absorption peak at 600 cm−1 was different between ionized intermediates and nonionized intermediates.

Modifications of GaAs/air interface under x-ray exposure have been investigated by means of x-ray reflectometry (XRR). For this purpose a GaAs/AlAs multilayer system was continuously monitored for 90 h while acquiring XRR profiles. Three different starting models for the oxide/contaminants layer were tested for the analysis of XRR data and discussed. The main effect of x-ray exposure, revealed by the three different approaches, is an increase in the thickness of the gallium and arsenic oxides until a saturation value (about 3.0 nm) is reached after about 50 h. Total reflection x-ray fluorescence analysis performed on a couple of twin samples, either irradiated and nonirradiated, confirms that the oxidation process is promoted by x-ray exposure and indicates the presence of a richer As oxide phase at the surface of the x-ray irradiated samples.

Tetrairidium dodecacarbonyl (Ir4(CO)12) is an organometallic compound called metal cluster complex which has a molecular weight of 1104.9. To investigate its irradiation effect, silicon substrates sputtered with 10keV Ir4(CO)7+ were analyzed by high resolution Rutherford backscattering spectrometry. Experimental results were examined on the basis of a conventional theory of simultaneous implantation and sputtering. The introduction of oxygen gas during sputtering proved to form a thick oxide layer in the substrate, resulting in iridium segregation at the silicon-oxide interface and carbon accumulation near the surface. It was confirmed that oxygen partial pressure significantly affected the characteristics of an altered layer beneath a sputtered surface.

A tip characterizer for atomic force microscopy (AFM) was developed based on the fabrication of multilayer thin films. Comb-shaped line and space (LS) and wedge-shaped knife-edge structures were fabricated on a GaAs substrate. GaAs∕InGaP superlattices were used to control the width of the structures precisely, and selective chemical etching was used to form sharp edges on the nanostructures. The minimum size of the LS structure was designed to be 10nm, and the radius of the knife edge was less than 5nm. These nanostructures were used as a well-defined tip characterizer to measure the shape of a tip on a cantilever from line profiles of AFM images.

Tetrairidium dodecacarbonyl, Ir4(CO)12, is a metal cluster complex which has a molecular weight of 1104.9. Using a metal-cluster-complex ion source, it has been demonstrated that stable ion beams of Ir4(CO)7+ were produced. Energy dependence of sputtering yield of silicon bombarded with Ir4(CO)7+ ions was investigated at a beam energy from 2to10keV at normal incidence. Experimental results showed that the sputtering yield varied substantially with beam energy. The sputtering yield at 10keV was higher than that with SF5+ or Ar+ ions by a factor of 3–24, whereas the sputtering yield at 3keV was lower than that with Ar+ ions. In the case of 2keV, deposition was found to occur. The substantial variation in the sputtering yields was examined using empirical equations for calculating sputtering yields. It was shown that the high sputtering yield at 10keV would be due to what is called “nonlinear effect” unique to complex-projectile bombardment. It was also indicated that the substantial variation in the sputter...

Secondary ion mass spectrometry analyses were carried out using a metal cluster complex ion of Ir4(CO)7+ as a primary ion beam. Depth resolution was evaluated as a function of primary ion species, energy, and incident angle. The depth resolution obtained using cluster ion bombardment was considerably better than that obtained by oxygen ion bombardment under the same experimental condition due to reduction of atomic mixing in the depth. The authors obtained a depth resolution of ∼1nm under 5keV, 45° condition. Depth resolution was degraded by ion-bombardment-induced surface roughness at 5keV with higher incident angles.