A scalable volume-confined phase change memory using physical vapor deposition

To improve writing bandwidth for phase change memory (PCM) volume-confined cells are proposed to reduce the reset current [1, 2]. So far, CVD or ALD GST must be used to fill the small hole, with several negative issues. This work proposes and demonstrates a PVD GST volume-confined structure by using an isolation-last process. In our structure, a low aspect ratio (< 1) trench is created and PVD GST is deposited in the bottom and the sidewalls of the trench uniformly, and then covered by SiN. This protects the GST from etching damage and small VC phase change elements can be fabricated. The electrical characteristics show much reduced reset current and good endurance behavior because of the improved heating efficiency and the congruent melting [3] in VC PCM. PVD GST is much more flexible in materials selection and doping, thus has better scalability because of the ideal PC element size match with the selecting device.