Masaya Muranaka

The Analysis of the Defective Cells Induced by COP in a 0.3-micron-technology Node DRAM

The influence of a crystal originated pit (COP) on the deep sub-micron dynamic-random-access-memory (DRAM), was clarified by the investigation of the defective memory cells using 0.3 microns process test-element-group (TEG) which can operate as an actual DRAM. COP constrains the growth of field oxide film and leads to degradation of the isolation characteristics between the adjacent memory cells.

Low-cost p-/p- epitaxial silicon wafers for densely packed metal-oxide-semiconductor devices

Improvements of gettering actions in the prototype p - /p - thin-film silicon epitaxial wafers (1 μm thick film) have been investigated in conjunction with avoiding failures of crystal-originated particles which degraded isolation leakage between memory cells of densely packed metal-oxide-semiconductor (MOS) devices. In order to compensate for the appearance of a kink in current-voltage curves in MOS capacitors caused by undesirable impurities, an optimized gettering and evaluation method are proposed, leading to a low-cost Czochralski-grown substrate. We pinpointed the importance of the epitaxial thickness, proposing an improved type of p - /p - epitaxial wafer with a 3-5 μm thick film that is cheaper than current p - /p + epitaxial wafers. This p - /p + epitaxial wafer meets the requirements for future miniaturized devices formed on large diameter wafers (e.g., 300 mm diam wafers).