Katsumi Takiguchi

Effects of oxygen pressure in reactive ion beam sputter deposition of zirconium oxides

The mechanism of reactive ion beam sputtering is investigated. The experimental results indicate that the pressure decrease during sputtering, the properties of Zr–O films, and the deposition rate are all strongly influenced by oxygen partial pressure. A new model which takes into account the gettering action of the deposition material and deals with the number of sputtered and gaseous particles is presented for reactive ion beam sputtering of metal. The theoretical values are compared with experimental results of the reactive ion beam sputtering. It is found that the calculated values agree extremely well with the oxygen partial pressure decrease and the deposition rate measured experimentally.

Preparation of CoCr thin films on polymer substrates by ion beam sputtering

CoCr thin films have been deposited on polymer substrates by ion beam sputtering. The magnetic and crystallographic properties have been investigated in the films deposited under a range of preparation parameters such as ion acceleration voltage, substrate temperature, and substrate bias voltage. The typical half‐value width of the x‐ray rocking curve Δθ50 is 10°. Transmission electron microscopy revealed that the films on the polyimide substrate under high substrate voltage showed columnar structure, but that without the voltage there were coarse grains and no clear columnar structure. The relations among coercive force (Hc⊥), saturation magnetization (Ms⊥), Δθ50, and Co content are discussed.

DEPOSITION OF HIGH-PURITY Nb FILMS BY TETRODE SPUTTERING.

Niobium thin films with extremly low resistivity (14.7 μΩ cm) have been deposited by tetrode sputtering in Ar gas purified by the getter action of titanium sublimation pump. The effect of gaseous impurities on the resistivity, superconducting transition temperature, and crystal structure were investigated. The superconducting transition temperature of such films was enhanced to 9.8±0.1 K and the temperature coefficient of resistance was increased to +3.0×103 ppm/deg.

The effect of charged particles when preparing ZnO thin film by ion beam sputtering deposition

Abstract Zinc oxide films have been prepared by ion beam sputtering deposition. The irradiation effects of the charged particles on the ZnO film crystallographic orientation during deposition are studied. Two methods are adopted to control the bombardment of the charged particles. One applies a bias voltage to the substrate, and the other bombards the substrate with ions. When the substrate is positively biased, the c -axis preferred orientation of the ZnO film is destroyed by the negatively charged particles. When the substrate is negatively biased, or irradiated with argon ions from a side ion gun, certain conditions lead to c -axis orientation. When the substrate is irradiated with oxygen ions, a change to c -axis orientation can clearly be observed. Positive oxygen ion irradiation presumably has an effect on the formation of ZnO film c -axis orientation.

Development of a low energy ion source with multicapillary anode

Abstract A new type of hot cathode ion source which has a multicapillary anode and a discharge stabilizer electrode has been developed. There are two special features in this ion source. The gaseous flow is intense and of the collimated beam type, because it is introduced through the multicapillary anode. A high ion current density ( > 5 mA/cm 2 ) can be obtained because discharge in high vacuum can continue with the help of the stabilizer electrode. At a stabilizer voltage ( V s ) of 50 V, ion current densities of 2.2 and 6.1 mA/cm 2 were obtained at acceleration voltages ( V acc ) of 20 and 200 V, respectively. The ion energy was dependent on V d , and the full width at half maximum (FWHM) of its distribution was less than 15 eV. Cu films were etched by this ion source. The etching rate ( E r ) was 150 A/min at V acc = 100 V. The relationship between the etching rate and V acc was represented by E r ∝ ( V acc ) α . The values of α were 2.0 in the region of V acc ≤ 100 V and 1.0 for V acc ≥ 100 V.

Pressure dependence of the electrical properties of TaN thin films

Abstract The pressure dependence of the electrical properties of TaN thin films was studied with a view to using the films for pressure measurement over a wide range. These films have properties that make them suitable for use as sensors in resistive thermoconductive vacuum gauges: a large effective heat-conducting area and a large temperature coefficient of resistance. The TaN thin films were deposited by reactive sputtering onto Corning 7059 glass. The sensor thus formed was found to be sensitive to pressure changes in the range 7 × 10 −5 −760 Torr . The sensitivity of the gauge increased with the resistance of the film and could be varied by changing the film dimensions even when the surface area was kept constant; it also increased with increasing surface area of the film.