LASER-MACHINING THIN-FILM ELECTRODE ARRAYS ON QUARTZ CRYSTAL SUBSTRATES

The feasibility of laser-machining quartz crystal resonators for frequency and inter-resonator coupling adjustment has been demonstrated. The inter-resonator coupling has been adjusted by altering the geometry of the electrode array. The frequency has been adjusted by vaporizing material to form an array of holes on the electrode surface. The results indicate that extremely fine adjustments of inter-resonator coupling and resonator frequency can be achieved. Frequency adjustments greater than one part in 108 have been demonstrated. No degradation of the crystal unit electrical parameters could be detected as a result of the machining process. Furthermore, laser trimming lends itself to automated processing without the need for elaborate vacuum equipment as is presently required with some adjustment techniques. Laser trimming also appears to be ideally suited for adjustment of high-frequency resonators where fine tolerances are required. © 1969 The American Institute of Physics.