Dynamic RAM

6

Advanced DRAM Technologies

6.1    Introduction

Shrinking technology has remained the most important priority for DRAM development. At the same time it is responsible for most of the challenges. When the requirement of small area enforced adoption of the three-dimensional cell instead of the planar cell, technological advancements followed in parallel for the trench cells as well as for the stacked cells (and their variations), having their own advantages and limitations. From a topological point of view, the trench cell DRAM was found to be better as its capacitor was below the silicon surface. However, increase in DRAM density required a deeper trench for realizing sufficient storage capacitance; a bit impractical. The feature of low thermal ...