Scaling of Phase Change Memory Cell: Reducing Contact Size Beyond the Limit of Lithography

Phase change memory (PCM) has emerged as a highly promising candidate for next‐generation nonvolatile memory technologies, owing to its rapid operation speed, superior endurance, and compatibility with fabrication process. Conventional PCM fabrication predominantly depends on the photolithography tool. However, this approach encounters intrinsic limitations as device critical dimensions scale down to the sub‐100 nm level. The limitations include restricted resolution capabilities, the complexity of the multi‐patterning process, elevated manufacturing costs, and challenges in adapting to three‐dimensional cross‐point cell architectures. Moreover, lithography‐based methods face difficulties in minimizing the contact size between phase change material and heater electrode, thereby constraining the development of low‐power, high‐density PCM devices. In response to these challenges, there has been a growing interest in lithography‐independent fabrication techniques, which are essential for the advancement of cost‐effective, high‐density PCM devices. This article provides a comprehensive overview of recent advancements in lithography‐independent fabrication strategies, emphasizing critical methodologies such as etching‐derived patterning, imprint technology, specialized deposition processes, and the utilization of novel electrode materials. Additionally, current challenges are examined, and prospective research directions are proposed, with the objective of guiding the development of low‐power, high‐density PCM through lithography‐independent approaches.