Process and Tool Monitoring Strategy for Advanced Magnetic Tunnel Junction Stack Deposition

This paper will present the method by which a magnetron physical vapor deposition (PVD) tool is monitored and controlled for purposes of depositing a Magnetic Tunnel Junction (MTJ) stack in a research and prototyping fab environment. The fabricated MTJ stack is utilized as an integral component of a Magnetoresistive Random Access Memory (MRAM) device and as such, stringent control of layer characteristics and dimension is critical to the performance of the overall device [1]. In this paper, the structure and deposition process of a MTJ stack will be briefly discussed in relation to key tool parametrics and wafer monitoring strategies. In addition, the paper will examine case studies showing the detection and containment of potential excursion events utilizing the presented monitoring strategies.