High Resolution Acoustic Microscopy with Low Frequency and Its Applications in Analysis of Ferroelectrics

摘要

Ferroelectrics have spontaneous polarization, which can be oriented along with electric field and show high dielectric constant, high switching speed, nonvolatile memory character and large capacity memories on a given silicon wafer. Large-scale manufacturing is presently underway to incorporate ferroelectric materials as storage and bypass capacitors in IC circuitry. Nondestructive observation of domain structure of ferroelectrics, dynamic behavior under external field and related phenomena is becoming significant. As a non-destructive and subsurface characterizing technique, the acoustic microscopy based on a commercial SPM was developed in our lab. Its working frequency is in the range of several kHz to decades of kHz, which is much lower than that of conventional acoustic imaging techniques. It also shows resolution of ～10nm. This technique was used for direct observation of local ferroelectricity, elasticity and defects on several inorganic functional materials, transparent PLZT ceramics, relax-based PMN-PT crystal and lead-free Bi_4Ti_3O_(12) ceramics without any special processing (polishing or etching) to the sample, which is particularly useful and convenient for analyzing ferroelectrics / semiconductor integrated material and devices.