Fabrication of a field effect transistor with an upside down T-shaped semiconductor pillar in SOI technology
Patent 6475890 Issued on November 5, 2002. Estimated Expiration Date: 
February 12, 2021. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
February 12, 2021. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesProcess for creating vias using pillar technology Trench dram cell with vertical device and buried word lines Patent #: 5977579 InventorAssigneeApplicationNo. 789939 filed on 02/12/2001US Classes:438/574, T-shaped electrode438/576, Into grooved or recessed semiconductor region438/578Forming electrode of specified shape (e.g., slanted, etc.)ExaminersPrimary: Nelms, David C.Assistant: Berry, Renee R. Attorney, Agent or FirmInternational ClassH01L 021/44AbstractFor fabricating a field effect transistor on a semiconductor substrate in SOI (semiconductor on insulator) technology, a pillar of semiconductor material is formed on a layer of buried insulating material. The pillar has a top surface and first and second side surfaces, and the pillar has a width, a length, and a height. A masking structure is formed on a center portion of the top surface of the pillar along the length of the pillar. A top portion of the height of the pillar is etched from exposed surfaces of the top surface of the pillar down to a bottom portion of the height of the pillar to form an upside down T-shape for the pillar. A gate dielectric material is deposited on any exposed surface of the semiconductor material of the pillar for a gate length along the length of the pillar. A gate electrode material is deposited on the gate dielectric material to surround the pillar for the gate length of the pillar. A drain and source dopant is implanted into exposed regions of the pillar to form a drain of the field effect transistor on a first side of the gate electrode material along the length of the pillar and to form a source of the field effect transistor on a second side of the gate electrode material along the length of the pillar. In this manner, for a given height and width of the semiconductor pillar, any point of a cross-section of such a pillar is more closely located to the gate bias applied at a surface of such a pillar to maximize effective drive current while minimizing undesired short channel effects of the field effect transistor.Other References
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