PIEZOELECTRIC MONOCRYSTAL WAFER FOR PSEUDO SURFACE ACOUSTIC WAVE DEVICE AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To provide a piezoelectric monocrystal water which is used for a pseudo surface acoustic wave device, excludes any influence of bulk waves and has its small warp and satisfactory production yield by grinding the back side of the wafer with the power obtained by the power spectrum having a specific value or lower in a specific range of space frequency. SOLUTION: The power spectra are put in a specific range by calculating the power spectra of various surface states of the back side of a piezoelectric monocrystal wafer which is used for a pseudo surface acoustic wave device. The specific range of the power spectra is made into P(k)=10<6> k<-3> nm<3> or less in a range of space frequency (k) that is higher than 0.1μm<-1> and lower than 1μm<-1> with the power deigned as P(k). Furthermore, it's desirable to set the direction 2 that is vertical to a wafer surface 3 in a range of 33 deg. to 46 deg. toward an axis Z from an axis Y with an axis as the center in regard to a lithium tantalate monocrystal wafer.