SIGNIFICANT IMPROVEMENT IN DEVICE PERFORMANCE OF ADVANCED DYNAMIC RANDOM ACCESS MEMORY BY HOT WALL-BASED SINGLE WAFER RAPID THERMAL ANNEALING

摘要

To overcome the difficulties in lamp-based, cold wall rapid thermal processing (RTP) systems, a comparative annealing study of several critical RTP process steps was performed using a hot wall-type single wafer rapid thermal furnace (SRTF) system. In the SRTF system, unlike cold wall-type (lamp-based) RTP systems, the wafer is the coldest object in the process chamber at all times. In mass production of 512 Mbit DRAM devices with 110 nm design rules, significant improvement in electrical characteristics such as channel resistance variation and charge holding time, was obtained by switching annealing steps from a lamp-based RTP system to a furnace-based SRTF system. The flatness of wafers after annealing in the SRTF system was also improved up to 50 times compared to those annealed using the lamp-based RTP systems.