Understanding Smart Sensors - Nomads.usp

314 Understanding Smart Sensorsthan 98%, dropping from 910 to 15 microcents per transistor for the third yearof MPU production. The number of logic transistors will increase by over 48times, from 3.7 million to 180 million. Unfortunately, there are no direct predictionsabout micromachining technology or sensors. However, the part thatmakes any sensor smart—the computational engine—is increasing at a phenomenalrate. At some point in the future, the supercomputer that performstoday’s laboratory calculations will be a portable computer with similarperformance.Sensing technology will play an important role in developing the nextgeneration of semiconductor technology. Sandia National Laboratory hasdeveloped a silicon chip with up to 250 microsensors to monitor the mechanical,chemical, and thermal environments of integrated circuits [4]. The chipcan be used during prototyping, manufacturing, or any time during the life ofthe chip to monitor critical parameters that could affect performance. Theassembly test chip with its onboard polyimide and Al 2 O 3 moisture sensors, piezoelectricstrain gauges, electrostatic discharge and corrosion detectors, mobileion detectors, and thermocouples promises to play an important role in developingsemiconductor technology.The scale of future semiconductors will require measuring and monitoringtechniques that are well beyond today’s capability, especially if they will beused on a day-to-day basis to monitor production processes and measure qualitycontrol. The use of contamination sensors for measuring and monitoringparticulates and moisture is among the recommendations from the SIA roadmap[5]. Candidates for sensors include low-cost gas analysis sensors such asresidual gas analysis, optical emission spectroscopy, and intracavity laser spectroscopy.The integration of such sensors into online equipment was recommended.Metal and total-oxidizable-carbon contamination measurements inliquids were also considered essential. The report frequently cites the need tomonitor wafer contamination during processing as a key to achieving manufacturableproduct as the critical dimensions shrink. Undoubtedly, sensors thatallow semiconductor manufacturers to achieve the predicted capability will bepursued and implemented as they are available. The Sematech (a consortium ofsemiconductor manufacturers) project to develop interoperable sensor andactuator standards confirms the industry’s desire to communicate the informationfrom those sensors in an intelligent or smart manner using a common protocol[6].In-situ smart sensors for wafer metrology have a high payback potentialfor the semiconductor industry. According to one technologist, direct measurementof the wafer state, such as film thickness and film composition duringprocessing, could save calibration setup, maintenance, and testing time [7].