MOS transistor in an integrated circuit and active area forming method
AssigneesSTMicroelectronics S.r.l., Koninklijke Philips Electronics N.V.
InventorsWalter De Coster, Meindert Lunenborg, Alain Inard, Jos Guelen
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Abstract
A method of forming an active area surrounded with an insulating area in a semiconductor substrate, including the steps of forming in the substrate a trench surrounding an active area; filling the trench with an insulating material to form an edge extending beyond the substrate surface at the periphery of the active area; forming a spacer at the periphery of said edge; and implanting a dopant, whereby the implantation in the area located under the spacer is less deep than in the rest of the active area.
Claims3
A method of forming a doped active area in a semiconductor substrate, comprising:
- forming first and second insulation areas on a surface of the substrate, the first and second insulation areas being spaced apart from each other and thereby defining a substrate region of the substrate between the first and second insulation areas, the substrate region having a first peripheral portion immediately adjacent to the first insulation area and a central portion spaced apart from the first insulation area;
- forming a spacer adjacent to the first insulation area and above the first peripheral portion of the substrate region;
- performing, with the spacer positioned above the substrate, a high-energy first implant of first dopant type into the substrate region to create a well that extends in the substrate at a bottom side of the first insulation area;
- and
- performing, with the spacer positioned above the substrate, a low-energy second implant of the first dopant type into the substrate region to create the doped active area, the spacer acting as a mask to allow dopants of the second implant to extend deeper into the central portion that into the first peripheral portion.
Dependencies are inferred from the claim text.