HRTEM Study on Resistive Switching ZrO2 Thin Films and Their Micro-Fabricated Thin Films

Abstract

For the next-generation nonvolatile memory material, the most promising candi‐ date is resistive random access memory (RRAM) which is nonvolatile memory with high density, high speed, and low power consumption. Resistive switching (RS) be‐ havior had been reported in various films including transition metal oxides, perov‐ skite, and chalcogenide. For further application, it is still a challenge to fabricate nanostructures of RS material. Micro-fabrication method involves traditional lithog‐ raphy, chemical etching, electron beam direct writing, nano-imprint, and so on. However, the procedure and the cost of these methods are relatively complex and high for semiconductors process. In this chapter, we demonstrate a method for fab‐ ricating sub-micro ZrO2 lattice by using sol-gel method combined with laser inter‐ ference lithography and micro-analysis with high-resolution transmission electron microscopy (HRTEM). Researchers used all kinds of techniques to investigate the mechanism such as con‐ ductive atomic force microscopy, HRTEM, and scanning electrical microscopy. De‐ spite the extensive research, much of the underlying mechanism is still unclear and controversial. This task can be accomplished only with advanced measurement and technique such as in HRTEM, local conductive atomic force microscopy, and so on. HRTEM sample preparation method for array dots is also discussed. In our re‐ search, the bipolar RS behavior can be observed successfully in this structure. And HRTEM observation was used to study the interface between the layers. RRAM unit consists of a conductive atomic force microscope tip as an anode, a ZrO2 lattice dot as RS material, and a copper electrode as a cathode.