Nitride cap formation in a DRAM trench capacitor
Patent 5937292 Issued on August 10, 1999. Estimated Expiration Date: 
October 17, 2016. 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.
October 17, 2016. 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 ReferencesDRAM cell having raised source, drain and isolation Dynamic random access memory having a vertical transistor Method of making double grid substrate plate DRAM cell array Patent #: 5521115 InventorsAssigneeApplicationNo. 730839 filed on 10/17/1996US Classes:438/243, Trench capacitor257/E21.651Capacitor in U- or V-shaped trench in substrate (EPO)ExaminersPrimary: Chang, JonAttorney, Agent or FirmInternational ClassH01L 021/824.2AbstractA method for forming an oxygen-impervious barrier on the oxide collar of a trench capacitor in a DRAM cell. The process consists of etching a shallow trench into the oxide collar which surrounds the polysilicon trench fill and isolating it from the single crystal semiconducting substrate material of the DRAM cell to a depth which is at least equal to or larger than the width of the oxide collar. A nitride layer with a thickness equal to or thicker than half of the width of the oxide collar is then deposited on the top surface of the freshly excavated oxide collar such that the aforementioned trench is completely filled with this nitride layer, and the entire surfaces of the substrate and polysilicon trench fill are completely covered. The newly formed nitride layer is then selectively overetched in order to completely remove it from the substrate and polysilicon trench fill surfaces, while still maintaining a sufficient thickness of this layer disposed on the oxide collar sufficient to prevent oxygen diffusion into the oxide collar. Alternatively, the nitride layer may be deposited as a thin layer sandwiched between the original oxide collar and an additional thermally deposited oxide layer.Field of SearchIncluding passive device (e.g., resistor, capacitor, etc.)Capacitor Multiple doping steps Utilizing stacked capacitor structure (e.g., stacked trench, buried stacked capacitor, etc.) Including doping of trench surfaces With epitaxial layer formed over the trench Trench capacitor Including isolation means formed in trench Doping by outdiffusion from a dopant source layer (e.g., doped oxide, etc.) MAKING PASSIVE DEVICE (E.G., RESISTOR, CAPACITOR, ETC.) Including doping of trench surfaces With epitaxial layer formed over the trench Having stacked capacitor structure (e.g., stacked trench, buried stacked capacitor, etc.) Multiple doping steps Including isolation means formed in trench Doping by outdiffusion from a dopant source layer (e.g., doped oxide) Trench capacitor | |
