| This dissertation is concerned with the development of novel wireless sensor technologies appropriate for semiconductor manufacturing applications. More specifically, the feasibility of placing sensors directly onto the surface of a standard silicon wafer is explored. Such a wafer-mounted sensor system would be fully integrated. It would include driver electronics, a power supply, and a communication system, in addition to the sensing elements. As a result, measurements can be made in-situ to extract the process state. With such sensor systems, processes can be automatically optimized, equipment can be efficiently diagnosed, and traditional test wafers can be replaced by more effective “smart” sensor wafers.; The status quo of metrology methods in use in the semiconductor industry is first discussed. From this discussion, a compelling case for wireless sensor systems is made. Next, the impediments associated with engineering this type of system are discussed, and possible solutions are proposed. The remainder of the dissertation describes the design, fabrication, and testing of two types of sensors for plasma etch processes.; First, a film thickness sensor for polysilicon etch processes is presented. This sensor measures the resistance of a thin polysilicon film, and uses this information to infer the film's thickness. Changes in the measured thickness, due for example to etching, can be directly sensed by this device. The sensor system incorporates a temperature sensor, both for measuring wafer surface temperature, and for compensation of the film thickness sensor against thermal variations. Design, fabrication, and testing results of this sensor are presented.; Next, a thermal flux sensor for plasma etch processes is developed. In plasma etch processes, there are many sources for the heat delivered to the wafer. The two most significant sources are the ion flux heating and the surface chemical reaction heating. The sensor discussed in this work is capable of separately measuring both effects, for use with equipment design, diagnostics, or control. Design, fabrication, and testing results of this sensor are presented.; Finally, future directions for this research topic are offered. In particular, alternate sensors, improved isolation, and novel uses for the sensor data are discussed. |
