Research Of Testing Methods And Set-up For Phase Change Random Access Memory

Phase-change random access memory (PCM) records and erases data by utilizing the thermal effect of the pulse current to make SET or RESET operation in its recording layer with a reversible phase-change structure of giant differential resistance between two phases. It has many advantages over existing memories such as non-volatile property, high scalability, high operational speed, low power consumption, long life, and compatibility with the CMOS technology and so on. As the most promising candidate for next-generation memory, PCM got rapid development nowadays and had made great breakthrough in recording materials, micro-manufacturing process and device performance. However, there are not enough attention on the techniques and standard of PCM testing. There was still no complete test method in the world. Based on the above point, this article focuses on a comprehensive description and comparison of PCM cells characterized by the basic electrical properties and test methods. In this work, the platform structures of test system, bonding technique of PCM-chip and chip function test were illustrated in detail.The inherent parameters which represent electrical characteristics of PCM-cell included crystalline resistance, amorphous resistance, DC I-V property, pulsed I-V property, the relationship between RESET pulse and the fraction of amorphalization state, the relationship between SET pulse and the fraction of crystallization state, data retention of PCM and endurance life and so on. The multifunction and high-precision PCM-cell testing system which was made of high-performance probe station, semiconductor characterization system and high frequency oscilloscope and DUT was used to measure these parameters completely. The electrical characteristics of PCM-cells had been further analyzed.The basic function of PCM-chip testing includes peripheral circuits (MOSFET, writing, erasing and reading circuit) and storage array. The novel PCM-chip testing system which consists of high-performance semiconductor characterization system, NI data acquisition card, computer, nanoseconds pulse generator, constant voltage source and DUT. The precision measurement of peripheral circuit performance and basic logic chip functional test had been realized, a fully functional chip testing requirements had been reached. In addition, the optimum wire bonding of several of the electrode material had been discussed.