Fabrication of a high density long channel DRAM gate with or without a grooved gate

摘要

The present invention lengthens gate conductors used in memory chips to limit leakage current, while still allowing the overall size of cells to remain the same. The channel length for each gate is increased by decreasing the size of spaces between gates. Decreases in space size occurs by using photolithographic image enhancement techniques. These techniques allow the space between gate conductors to be smaller while the gate size increases. In addition, a groove may be added that additionally lengthens the effective channel length and provides an additional electrical shield to limit leakage current. These techniques lead to the same density memory cells for a given process with less leakage. Finally, if grooved gate structures are used, having a longer gate conductor allows a three sigma process to be used, which increases yields.