The use of high resolution haze for control of SOI surface roughness in a volume production environment.

It is well known that the final surface roughness of SOI wafers has to be controlled to a very tight tolerance in order to maintain transistor parameters required for today´s advanced node semiconductor devices. The traditional method for this measurement is to use an atomic force microscope (AFM), but the tool´s throughput and the area sampled by each measurement are very limited, and AFM repeatability is low. Such measurements can be used during process development, but are not practical during high-volume production. In this paper we will discuss the use of the haze signal from an industry-standard unpatterned wafer inspection system (KLA-Tencor´s Surfscan® SP2) equipped with an optional metrology proxy and process signature module (SURFmonitor™), as a proxy for the SOI surface roughness. We will discuss its applicability to a high volume production environment, including the importance of maintaining haze matching across a fleet of inspection tools and practical methods to ensure matching.