| 摘要 |
A process for forming a vertical semiconductor device having increased source contact area comprises forming on a silicon substrate a gate that comprises a layer of polysilicon deposited on a layer of oxide, and implanting and driving a dopant of a first conductivity type into the substrate to form a well region. A dopant of a second conductivity type is implanted and driven into the well region, to form a shallow source region in the well region, and a first layer of oxide is deposited over the gate and over the source and well regions in the substrate The first layer of oxide is etched to form a first spacer of oxide on the substrate adjacent the gate. A thin layer of nitride is deposited over the gate and over the source region, and a second layer of oxide is deposited over the thin nitride layer. The second layer of oxide is etched to form a second spacer of oxide that is separated from the first oxide spacer and the substrate by the thin nitride layer. Using the oxide and nitride spacers as a mask, the polysilicon layer in the gate and the source region in the substrate are selectively etched to remove the thin nitride layer from the gate and substrate, a portion of the gate polysilicon layer, and a portion of the source region, to forming in the source region a recessed portion that comprises substantially vertical and horizontal surfaces. A dopant of a first conductivity type is implanted and driven into the recessed portion of the source region, to form a shallow emitter region in the well region underlying the recessed portion of the source region. The second oxide spacer and the thin nitride layer separating it from the first oxide spacer are removed by etching, and a layer of conductive material is deposited on the remaining polysilicon layer and on the source region, whose recessed portion provides increased contact area with the conductive material. <IMAGE> |
