ULTRATHIN SINGLE-CRYSTALLINE SILICON ON QUARTZ (SOQ) BY 150-DEGREES-CWAFER BONDING

Single-crystalline silicon films with thicknesses as thin as 2000 Angs trom have been prepared on thermally mismatched quartz substrates by a simple wafer-bonding approach. Initial bonding at approximate to 80 d egrees C, storage at room temperature for more than 100 h and multi-te mperature (maximum 150 degrees C) consecutive annealing with a 1 degre es C min(-1) ramping rate have been adopted to strengthen the bond and to prevent debonding at the edge of the bonded pairs during annealing and etching, where thermal shearing and peeling stresses are maximum. Final etching by EDP (ethylenediamine-pyrocatechol-water) effectively reduces the peeling failure of the highly stressed thinned silicon la yer, mainly due to a reduced lateral oxide etching rate along the inte rface. The high carrier mobility in the single-crystalline silicon lay er and the transparent and insulating quartz substrate provides a new dimension of freedom in applications.