Low defect, high quality SIMOX material for bipolar device applications

The threading dislocation densities of 10⁸/cm² to 10¹⁰/cm² that are typical of SIMOX material are detrimental for bipolar structures and orders-of-magnitude reduction of defect density is still required to permit SIMOX (separation by implanted oxygen) material to be acceptable for high-performance bipolar and analog devices. Two methods have been developed to produce low-defect SIMOX wafers. In the first method, threading dislocation defects are reduced by low-dose Ge implantation and subsequent solid-phase epitaxial (SPE) regrowth. Ge implantation produces a strained and amorphized layer that during the subsequent SPE acts as an artificial interface and deflects or stops the propagation of threading dislocations. In the second method, threading dislocations are prevented by a multiple low-dose implantation and high-temperature annealing process. No defects were observed for implantation with doses up to 8×10¹⁷ O⁺/cm², and threading dislocation density has been reduced by three to four orders of magnitude. Continuous and uniform buried layers are formed with about 65% of the dose required by the standard SIMOX process. Preliminary results have shown that by use of these methods low defect, superior quality, SIMOX wafers for submicron CMOS and bipolar device applications can be produced