Abstract:
Body effects in vertical MOSFET transistors are considerably reduced and other device parameters are unaffected in a vertical transistor having a threshold implant with a peak at the gate and an implant concentration distribution that declines rapidly away from the gate to a plateau having a low p-well concentration value. A preferred embodiment employs two body implants-an angled implant having a peak at the gate that sets the Vt and a laterally uniform low dose implant that sets the well dopant concentration.
Abstract:
A method of manufacturing a transistor by using two layers of a silicon epitaxial layer is disclosed. In the first step of the manufacturing process, a spacer is formed around gate structures. Then, a first silicon epitaxial layer is grown on the wafer. Then, a second spacer is deposited and then etched, such that the second spacer remains around a gate structure. Next a second silicon epitaxial layer is grown on the first silicon epitaxial layer, and the second spacer is etched from around the gate structure. After etching the first oxide spacer, ions are implanted at a first energy level to form four junctions. Then a third spacer is deposited and etched, so that the third spacer remains around the gate structures. Then ions are implanted at a second energy level to form two more junctions, each of these two junctions being located between two of the earlier formed junctions. The junctions and the gate structures provide a transistor structure. The resulting transistor has a good short channel effect because the junction depths are preferably all aligned. It also has good drive current because the junctions created by ion implantation at a second energy level have low parasitic resistance.
Abstract:
In a method of making a dual work function gate electrode of a CMOS semiconductor structure, the improvement comprising formation of the dual work function gate electrode so that there is no boron penetration in the channel region and no boron depletion near the gate oxide, comprising:a) forming a gate oxide layer over a channel of a nMOS site and over a channel of a pMOS site;b) forming an undoped polysilicon layer over the gate oxide layer;c) masking the pMOS site, forming an a-Si layer over the nMOS site using a first heavy ion implantation, and implanting arsenic solely into the a-Si layer;d) masking the nMOS site formed by step c), forming an a-Si layer over the pMOS site using a second heavy ion implantation, and implanting boron solely into the a-Si regions;e) laser annealing the nMOS and pMOS sites for a short time and at an energy level sufficient to melt at least a portion of the a-Si but insufficient to melt the polysilicon; andf) affecting cooling after laser annealing to convert a-Si into polysilicon without gate oxide damage.
Abstract:
A method of manufacturing a transistor by using two layers of a silicon epitaxial layer is disclosed. In the first step of the manufacturing process, a spacer is formed around gate structures. Then, a first silicon epitaxial layer is grown on the wafer. Then, a second spacer is deposited and then etched, such that the second spacer remains around a gate structure. Next a second silicon epitaxial layer is grown on the first silicon epitaxial layer, and the second spacer is etched from around the gate structure. After etching the first oxide spacer, ions are implanted at a first energy level to form four junctions. Then a third spacer is deposited and etched, so that the third spacer remains around the gate structures. Then ions are implanted at a second energy level to form two more junctions, each of these two junctions being located between two of the earlier formed junctions. The junctions and the gate structures provide a transistor structure. The resulting transistor has a good short channel effect because the junction depths are preferably all aligned. It also has good drive current because the junctions created by ion implantation at a second energy level have low parasitic resistance.
Abstract:
A process for fabricating a single-sided semiconductor deep trench structure filled with polysilicon trench fill material includes the following steps. Form a thin film, silicon nitride, barrier layer over the trench fill material. Deposit a thin film of an amorphous silicon masking layer over the barrier layer. Perform an angled implant into portions of the amorphous silicon masking layer which are not in the shadow of the deep trench. Strip the undoped portions of the amorphous silicon masking layer from the deep trench. Then strip the newly exposed portions of barrier layer exposing a part of the trench fill polysilicon surface and leaving the doped, remainder of the amorphous silicon masking layer exposed. Counterdope the exposed part of the trench fill material. Oxidize exposed portions of the polysilicon trench fill material, and then strip the remainder of the masking layer.