Patent ID: 6251472
Filing Date: 2001-06-26
Classification: C23C,H01L

Abstract:
A method for forming an electrode pattern on a piezoelectric element for an ultrasonic motor, the electrode pattern including a plurality of shapes of electrode portions for selectively energizing corresponding portions of the piezoelectric element, thereby generating an ultrasonic vibration wave in the ultrasonic motor, the ultrasonic vibration wave generating a frictional driving force for a driving system, said method using a single electrode forming step in a vacuum deposition device and comprising the steps of:ultrasonic-washing a piezoelectric element with an ultrasonic washer;setting the ultrasonic-washed piezoelectric element on a pattern mask which is incorporated in a deposition umbrella and is made of a metal material having a surface roughness providing a maximum spacing between the piezoelectric element and the pattern mask not exceeding 0.1 mm, the metal material having a thermal expansion characteristic which maintains the maximum spacing between the piezoelectric element and the pattern mask under vacuum deposition conditions, the deposition umbrella being disposed within a film forming chamber of the vacuum deposition device, the pattern mask having a pattern formed therein corresponding to the plurality of shapes of electrode portions of the electrode pattern;discharging air from the interior of the film forming chamber to obtain a vacuum therein;irradiating the piezoelectric element with ion beams through the pattern mask with an ion acceleration energy in a range from 1.0 to 1.2 KeV, thereby irradiation cleaning a portion of the piezoelectric element exposed through the pattern mask and corresponding to the plurality of shapes of electrode portions of the electrode pattern; andafter said irradiating step, vapor depositing nickel through the pattern mask onto a surface of the irradiation cleaned portion of the piezoelectric element with an electron gun assisted by ion acceleration energy sufficient to form a nickel film having a final film thickness in a range of 0.5 to 1.0 .mu.m and an adhesion strength between the nickel film and the surface of the piezoelectric element in a range of 1.5-2.0 kg/mm.sup.2, the nickel film thereby forming a plurality of shapes of electrode portions corresponding to the pattern of the pattern mask and having insulating portions between the plurality of shapes of electrode portions.