Yield and Efficiency Improvements Using Multi-Field Hall Measurement for High
Volume pHEMT Production
Keywords: MBE, pHEMT, Hall measurement, characterization
Maximizing yield in pseudomorphic high electron mobility transistors (pHEMT’s) requires tight control of the electrical properties of the channel layer. Monitoring channel characteristics is therefore critical to keeping the process centered and screening out non-compliant material before the start of the costly fabrication process. The most common monitoring tools include non-contact sheet resistance and single-field Hall measurements. Unfortunately, these techniques provide an average value for the entire epi stack and cannot distinguish between the channel and heavily-doped cap of a typical pHEMT structure. In this paper we will describe the use of a commercially available multi-field Hall system for nondestructive testing of production material. This system is capable of separating the effects of multiple conducting layers, providing an effective monitor of the electrical characteristics of both the channel and cap layers.