PROCESS INTEGRATION EVOLUTION IN MANUFACTURING TECHNOLOGIES FOR FLASH MEMORIES

摘要

At the end of nineties, the semiconductor market is characterised by a continuous volume exponential growth, a dramatic price drop and a strong acceleration of new technology innovations for manufacturing integration. Indeed, the scaling process forecasted at the start of the decade by the SIA Technology Roadmap has been strongly accelerated and a differentiation between microprocessors and memories occurred. The segmentation has been driven by the "commodity" nature of memories and by the related strong issue of production cost. As a part of the Memory Family, this factor has been impacting the introduction of innovative process steps also on Non Volatile products like FLASH. Moreover, the evolution of the fabrication technology for flash memories has also been driven by its unique demand in terms of cell reliability and more precisely, in terms of cell cycling and data retention, that has forced technology evolution to develop specific process steps. In the following, a review of the main peculiarities of flash process fabrication modules is presented.