Advanced process control in semiconductor manufacturing

The manufacturing of semiconductor devices, already a complicated process involving hundreds of individual steps of film deposition, pattern etching and planarization, is becoming even more complicated. The industry is moving to adopt smaller critical dimensions, 300 mm. diameter wafers and a variety of new materials such as copper/low-k interconnect technology, silicon on insulator substrates, silicon germanium epi layers, high k dielectrics, more complicated gate structures and chemically amplified photoresists. Many of these changes require tightening of the process specifications and measurement and control of new parameters such as film composition, trench depth, exhaust gas composition, etc. Introducing these changes while maintaining product quality and reducing costs is a formidable challenge. Integrated metrology with run-to-run control can facilitate the introduction of these new technologies because of its ability to improve process control while at the same time reducing manufacturing costs. Fault detection and classification offers an opportunity to identify process excursions quickly to minimize scrap and reduce down time. These techniques classified as Advanced Process Control (APC) are being cautiously tested and adopted by the industry. This paper tells some of this story.