One-Chip RF IC Using Zero-Temperature-Coefficient SAW Devices on AlN Films.

For a compact mobile communication，new thin-film technologies are required for integrating“zero-temperature-coefficient”surface-acoustic-wave(SAW)devices and“active”semiconductor devices into one chip，which should be called射频IC on a silicon sapphire(SOS)or a Si substrate.We have carried out detailed and systematic studies on the one-chip RF IC using zero-temperaturecoeffico-temperaturecoeffico-temperaturecoefficent！We have performed the following studies.1。We have tested the detailed qualities of AlN films for the device fabrication；(1)effects of growth temperature.(2)SAW propagation loss and dispersion vs.frequency and film thickness，(3)effects of AlN film qualities on the temperature coefficient of delay for SAW propagation，and so on.The reproducibility of zero temperature coefficient of delay for SAW propagation seems to depend on oxygen contamination in AlN film by Auger analysis，bero temperature coefficient of delay for SAW propagation seems to depend on oxygen contamination in AlN film by Auger analysis，device fabrication.In order to pick up the full potential of AlN film，an example of one-chip RF IC of spread spectrum demodulator was proposed.The one-chip included SAW band pass filters，SAW oscillators，SAW correlators and delay lines，amplifiers，mixers and AGC circuits with AlN-SOS combination.The AlN film growth，especially the growth temperature，should have a compatibility with silicon device fabrication process。Using a low pressure MOCVD and also a plasma enhanced MOCVD，the growth temperature has been decreased below 850°C.It could be concluded that AlN film is a prospective material for thin film SAW devices and has a high potential for a one-chip RF IC such as integrated spread spectrum transciever incorporating zero-temperature-coefficient SAW correlators.

For a compact mobile communication, new thin-film technologies are required for integrating "zero-temperature-coefficient"surface-acoustic-wave(SAW) devices and "active" semiconductor devices into one chip, which should be called RF IC on a silicon on sapphire (SOS) or a Si substrate.We have carried out detailed and systematic studies on the one-chip RF IC using zero-temperaturecoefficient SAW devices on AlN films for three years (1983-1985). We have performed the following studies.1. We have tested the detailed qualities of AlN films for the device fabrication; (1) effects of growth temperature.(2) SAW propagation loss and dispersion vs.frequency and film thickness,(3) effects of AlN film qualities on the temperature coefficient of delay for SAW propagation,and so on.The reproducibility of zero temperature coefficient of delay for SAW propagation seems to depend on oxygen contamination in AlN film by Auger analysis,but we will need more detailed and careful studies under high-purity growth condition.2. In order to pick up the full potential of AlN film, an example of one-chip RF IC of spread spectrum demodulator was proposed. The one-chip included SAW band pass filters, SAW oscillators, SAW correlators and delay lines, amplifiers, mixers and AGC circuits with AlN-SOS combination. The AlN film growth, especially the growth temperature, should have a compatibility with silicon device fabrication process. Using a low pressure MOCVD and also a plasma enhanced MOCVD, the growth temperature has been decreased below 850 ゜C.It could be concluded that AlN film is a prospective material for thin film SAW devices and has a high potential for a one-chip RF IC such as integrated spread spectrum transciever incorporating zero-temperature-coefficient SAW correlators.