Real-time material quality prediction, fault detection, and contamination control in AlGaN/GaN high electron mobility transistor metalorganic chemical vapor deposition process using in situ chemical sensing
Gallium nitride and its alloys promise to be key materials for future heterojunction semiconductor devices aimed at high frequency, high power electronic applications. However, manufacturing for such high performance products is challenged by reproducibility and material quality constraints that are notably higher than those required for optoelectronic applications. To meet this challenge, in situ mass spectrometry was implemented in AlGaN∕GaN∕AlN metalorganic chemical vapor deposition processes as a real-time process and wafer state metrology tool. In particular, the various pregrowth gas phase impurity levels within the reactor, measured by mass spectrometry in real time, were correlated to photoluminescence band-edge and deep-level properties measured postprocess. Band-edge intensities increased and deep-level intensities decreased with lower oxygen-containing impurity levels in the pregrowth environment. These real-time indications of oxygen impurity incorporation were used for fault detection and to ...
In situ chemical sensing in AlGaN/GaN high electron mobility transistor metalorganic chemical vapor deposition process for real-time prediction of product crystal quality and advanced process control
Gallium nitride and its alloys promise to be key materials for future semiconductor devices aimed at high frequency, high power electronic applications. However, manufacturing for such high performance products is challenged by reproducibility and material quality constraints that are notably higher than those required for optoelectronic applications. To this end, in situ mass spectrometry was implemented in AlGaN∕GaN∕AlN∕SiC metalorganic chemical vapor deposition processes as a real-time process and wafer state metrology tool. Dynamic chemical sensing through the process cycle, carried out downstream from the wafer, revealed generation of methane and ethane reaction byproducts, as well as other residual gas species. Using the methane/ethane ratio, the GaN epilayer crystal quality was shown to be predictable in real time to a precision of 2%–5%. This was verified by postprocess x-ray diffraction using the full-width at half-maximum height of GaN on-axis (002) and off-axis (102) rocking curve peaks as a me...
Traceability strategy for gear-pitch-measuring instruments: development and calibration of a multiball artifact
There is a strong demand to ensure the traceability of gear-measuring instruments (GMIs). We propose a multiball artifact (MBA) for the evaluation of pitch-measuring accuracy. The aim of the MBA is to transfer the minimum uncertainty from a calibrated value at the National Metrology Institute of Japan (NMIJ) to a measured value of GMIs at a shop floor. The MBA is composed of equally spaced high-accuracy balls around an axis. The pitch-measuring accuracy of GMIs is evaluated by measuring the angular pitch deviation of the balls instead of the angular pitch deviation of a gear. We calibrated the angular pitch deviation using a coordinate measuring instrument (CMM) at the NMIJ and adapting a multiple-orientation technique. We proposed a calibration strategy of the angular pitch deviation. The calibration value of the pitch deviation for the MBA at the NMIJ was obtained with a measurement uncertainty (U95) of 0.2 µm. We evaluated the pitch-measuring accuracy of a GMI using the calibrated MBA. Each value of U95 for the cumulative and single pitch deviations for the left and right flanks was less than or equal to 0.5 µm. The small uncertainty was transferred from the NMIJ to the GMI.