Fast-Switching Valves for High-Productivity ALD

摘要

Fast-switching valve performance is key to ALD film quality and tool productivity. During ALD, these valves open and close many millions of times, requiring the highest reliability and precision. High-productivity atomic layer deposition (ALD) processes are being driven by semiconductor applications (e.g., capacitor, gate and interconnects) requiring ultrathin films or conformal coatings with precise thickness control. ALD is particularly effective on surfaces with high aspect ratios or where graded compositions (i.e., one layer consists of one material and the next layer ofanoth-er) are required. Future memory devices referenced in the International Technology Roadmap for Semiconductors (ITRS), such as magnetic RAM (MRAM) and phase-change memories, nanofloat-ing gates, single-electron and molecular memories, may initially employ topologies with relatively relaxed aspect ratios compared with today's DRAM devices. But they all require ultrathin films, and eventually they will all migrate toward moderate, if not extreme, aspect ratios.