Buried layer substrates: Economically enhancing device performance

Buried layer substrates formed by high-energy implantation and rapid therma l annealing are an attractive alternative to epitaxial substrates where hig h performance is required at lower cost. The heavier p-type doping and clos e proximity to the active devices make buried implanted layers much more ef fective than epitaxial wafers in eliminating transient latch-up events. The unique defect control ability of buried layer substrates lowers diode leak age and improves gate oxide integrity relative to unimplanted substrates. T he heavy p-type region of a boron buried layer implant is also effective at gettering metallic contaminants such as copper.