发明授权
US4398338A Fabrication of high speed, nonvolatile, electrically erasable memory cell and system utilizing selective masking, deposition and etching techniques 失效
使用选择性掩蔽,沉积和蚀刻技术制造高速,非易失性,电可擦除存储单元和系统

Fabrication of high speed, nonvolatile, electrically erasable memory
cell and system utilizing selective masking, deposition and etching
techniques
摘要:
A process for fabricating an electrically erasable nonvolatile memory cell comprises forming a first region of insulating material which is less than about 200 Angstroms thick on a selected surface portion of an electrically-isolated relatively lightly doped pocket of epitaxial silicon of a first conductivity type such that first and second surface areas of the epitaxial pocket are exposed. Regions of the epitaxial pocket underlying the first and second exposed surface areas are doped such that first and second relatively lightly doped regions of a second conductivity type are formed in the epitaxial pocket. Relatively heavily doped polysilicon regions of the first conductivity type are formed on the first insulating region and on the second relatively lightly doped epitaxial region. Insulating material is formed over exposed surfaces of the first polysilicon region and the second polysilicon region such that first and second surface portions of the second relatively lightly doped epitaxial region are exposed. The regions of the epitaxial pocket underlying the surface of the first relatively lightly doped epitaxial region and the first and second surface portions of the second relatively lightly doped epitaxial region are doped such that first, second and third relatively heavily doped epitaxial regions of the second conductivity type are formed in the epitaxial pocket. Relatively heavily doped polysilicon of the second conductivity type is formed on the insulating regions covering said first conductivity type polycrystalline regions.
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