Research Of Micro-fabrication And Performance For Asymmetric Phase Change Memory Cells

Phase change random access memory (PCRAM) is a random access memory whichstores data using Chalcogenide materials as storage medium, changes its phase betweencrystalline and amorphous to write and erase data using electric energy. PCRAM which isgetting rapid development has many advantages, such as high operate speed, long cyclelife，non-volatile, high scalability, low power consumption, cell size, multi-level storage,compared with the CMOS technology and so on. Based on the above points, PCRAM isrecognized as a promising candidate of the next-generation nonvolatile memory.The biggest problem in the research is the operating current too large. In this work，inorder to improve the write information current pulse too high and the phase change timeconstraints for practical phase-change random access memory，using the soft ANSYSsimulation compares traditional T-type structure with asymmetric structure and coming toa conclusion. The latter’s performance of thermal properties and electrical properties issuperior to the former. Then designing and using of lithography, sputtering, and lift offprocesses to achieve the five-layer asymmetric structure basic unit of phase-changememory.The result show that，using photolithography, sputtering, and lift off of processes tofabricate eight basic unit phase-change memory cell of five-layer asymmetric structurescan repeatedly rewritable. Get the right curve and well positioned meeting the importantperformance parameters of the PCRAM. Researching the thickness of second layer andthird layer and asymmetry, then getting the best asymmetric structure which is beneficialto reduce the current and the phase-change memory optimal time, further improve theperformance of the device unit.