NUCLEATION MECHANISM OF SPIMOX (SEPARATION BY PLASMA IMPLANTATION OF OXYGEN)

Buried oxide layers in Si were fabricated using the SPIMOX (separation by plasma implantation of oxygen) technique. The implantation was car ried out by applying a negative bias to a Si substrate wafer immersed in an oxygen plasma. An implantation time of 2-3 min was required to i mplant the oxygen at doses ranging from 1 x 10(17) atoms cm(-2)-3 x 10 (17) atoms cm(-2). At a lower ion dose (1 x 10(17) atoms cm(-2)), buri ed oxide precipitates were observed. At a higher dose (3 x 10(17) atom s cm(-2)), a continuous buried oxide layer could be obtained, as indic ated by cross section transmission electron microscopy (XTEM) and Ruth erford backscattering spectrometry (RES). By optimizing the concentrat ion ratio of O+ and O-2(+) in the plasma and the implantation fluence, a double oxide layer (Si/oxide/Si/oxide/Si) structure could be produc ed in a single implantation step.