A systematic team approach for improving LPCVD silicon nitride reactor performance

Silicon nitride, often used to define the device active area, is a critical film with a long history in the semiconductor industry. The film is typically formed in a Low Pressure Chemical Vapor Deposition (LPCVD) reactor. As device geometries shrink below 0.5 μm, the need for repeatable nitride particle control is essential to yielding product. Achieving consistent uptime on these LPCVD reactors is equally important to meet increasing productivity requirements. This paper demonstrates how the performance of two horizontal silicon nitride reactors was greatly improved and particle excursions were reduced through a series of process and hardware improvements developed by a team of engineers and technicians. The team started by identifying all known process and equipment failures. Next potential solutions for the failures were developed. The team utilized a systematic approach so that both technical and practical issues were addressed. The potential solutions were ranked and then implemented based on the ones which gave the most return on investment. The most significant technical problem addressed was the effect of the pumpdown delay following door seal on particle performance. Many of the solutions were associated with upgrades that reduced the time it takes for the system to begin pumping down from atmospheric pressure. As a result the number of particle excursions were reduced by a factor of three. Other hardware upgrades were done to reduce intermittent pumpdown and ventup failures. A 40% improvement was seen in the performance of the two nitride systems after the solutions were implemented