Method of making a piezoelectric shear wave resonator
First Claim
1. A method of depositing a film of piezoelectric material on a substrate, the film having a uniform, controlled, inclined C-axis orientation comprising:
- providing a dc planar reactive sputtering system having a chamber containing a cathode for holding a target, an anode spaced from and parallel to the cathode for holding the substrate and a reactive gas,establishing an electrical field between the cathode and the anode to sputter the target such that the target material ionizes to form an ion flux which reacts with the reactive gas forming the piezoelectric material which deposits on the substrate,providing a positively biased control electrode in the chamber near the substrate and establishing a second, dc electrical field between the control electrode and the anode to collect the electron current and control the ion flux, the electrode position and the strength of the dc field being sufficient to alter the direction of the ion flux as it strikes the substrate to control the orientation of the C-axis away from the direction of the control electrode, the distance of the electrode above the plane of the substrate and the strength of the second electrical field controlling the degree of inclination of the C-axis, thereby forming a film of piezoelectric material having a uniform, controlled, inclined C-axis.
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Accused Products
Abstract
An acoustic shear wave resonator comprising a piezoelectric film having its C-axis substantially inclined from the film normal such that the shear wave coupling coefficient significantly exceeds the longitudinal wave coupling coefficient, whereby the film is capable of shear wave resonance, and means for exciting said film to resonate. The film is prepared by deposition in a dc planar magnetron sputtering system to which a supplemental electric field is applied. The resonator structure may also include a semiconductor material having a positive temperature coefficient of resonance such that the resonator has a temperature coefficient of resonance approaching 0 ppm/°C.
142 Citations
13 Claims
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1. A method of depositing a film of piezoelectric material on a substrate, the film having a uniform, controlled, inclined C-axis orientation comprising:
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providing a dc planar reactive sputtering system having a chamber containing a cathode for holding a target, an anode spaced from and parallel to the cathode for holding the substrate and a reactive gas, establishing an electrical field between the cathode and the anode to sputter the target such that the target material ionizes to form an ion flux which reacts with the reactive gas forming the piezoelectric material which deposits on the substrate, providing a positively biased control electrode in the chamber near the substrate and establishing a second, dc electrical field between the control electrode and the anode to collect the electron current and control the ion flux, the electrode position and the strength of the dc field being sufficient to alter the direction of the ion flux as it strikes the substrate to control the orientation of the C-axis away from the direction of the control electrode, the distance of the electrode above the plane of the substrate and the strength of the second electrical field controlling the degree of inclination of the C-axis, thereby forming a film of piezoelectric material having a uniform, controlled, inclined C-axis. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of forming a piezoelectric shear wave resonator comprising:
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providing a dc planar sputtering system having a chamber containing a cathode for holding a target, an anode spaced from and parallel to the cathode for holding a substrate and a reactive gas, establishing an electrical field between the cathode and the anode to sputter the target such that the target material ionizes to form an ion flux which reacts with the reactive gas forming the piezoelectric material which deposits on the substrate, providing a positively biased control electrode in the chamber near the substrate and establishing a second, dc electrical field between the control electrode and the anode to collect the electron current and control the ion flux, the electrode position and the strength of the dc field being sufficient to alter the direction of the ion flux as it strikes the substrate to control the orientation of the C-axis away from the direction of the control electrode, the distance of the electrode above the plane of the substrate and the strength of the second electrical field controlling the degree of inclination of the C-axis, removing the substrate under a portion of the deposited film to form a cavity such that the film forms a plate spanning the cavity, and depositing a layer of electrically conductive material on each side of the film to form upper and lower electrodes for applying a current to the film to excite the film, thereby forming the shear wave resonator. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification