Integrated AlN/diamond heat spreaders for silicon device processing

Abstract

Growth and characterization of AlN and diamond films on the backside of a Si (100) wafer and the integration of AlN/diamond heat spreaders into silicon device technology is investigated. AlN film was deposited by pulsed dc reactive magnetron sputtering at 600 °C and diamond film was deposited by microwave plasma chemical vapor deposition at 900 °C. The films were characterized by x-ray diffraction and transmission electron microscopy for crystalline quality, by scanning electron microscopy for morphology, and by infrared thermography for heat spreading characteristics. The heat spreading characteristics of the silicon wafer with the composite AlN/diamond films were found to be superior to that of wafers with no heat spreaders or to the wafers with either single layer diamond or single layer AlN heat spreaders. Deep level transient spectroscopy and secondary ion mass spectroscopy were performed on the samples with and without the heat spreader to determine the concentration of the impurities that may have been introduced during deposition of AlN or diamond. The results showed that the purity of the wafers is not altered due to the deposition of AlN and diamond and subsequent device processing steps such as high temperature oxidation. The device characteristics were studied by fabrication of Schottky diodes on the wafers with the composite AlN/diamond heat spreader and compared with that of devices on wafers with no heat spreader. The device characteristics were found to be similar and unaffected by integration with an AlN/diamond heat spreader. Integration of AlN/diamond heat spreaders with silicon device processing has been shown to be successful.