OXYGEN ISOTOPIC EXCHANGE BETWEEN AN O-18-TEMPERATURE ANNEALING( SI LAYER AND A NATURAL SIO2 CAPPING LAYER DURING HIGH)

To understand the effects of the SiO2 capping layer on the growing bur ied SiO2 layer a silicon wafer was implanted at 680 degrees C with 90 keV O-18(+) to a dose of 4.3 X 10(17 18) O+/cm(2). After the depositio n of an similar to 500 nm natural SiO2 cap by the plasma sputtering, o ne piece of the implanted wafer was annealed at 1360 degrees C for 6 h in a quartz silica tube in flowing nitrogen. There is clear evidence of diffusional mixing of the oxygen isotopes from the cap into the O-1 8(+) implanted layer during this annealing step, indeed a surprisingly large amount has taken place, in that approximately 41% of O-18 conta ined within the buried SiO2 layer has been exchanged with the cap.