Abstract A method for fabricating a storage electrode of a DRAM cell capable of preventing impurities from excessively moving from the storage electrode to diffusion regions. The storage electrode is formed by a double formation of polysilicon layers. An undoped polysilicon layer 11 is primarily deposited over the entire exposed surface of the resulting structure to a thickness corresponding to 40 to 50% of a predetermined thickness of the storage electrode. A doped polysilicon layer is secondarily deposited over the undoped polysilicon layer to a thickness corresponding to 60 to 50% of the predetermined thickness of the storage electrode. The doped polysilicon layer and the undoped polysilicon layer are subjected to a patterning so that predetermined portions thereof are removed so as to form the storage electrode.
A method for fabricating a DRAM cell, comprising the steps of: forming a MOSFET on a silicon substrate; forming an insulating layer over said MOSFET; etching a portion of said insulating layer to form a contact hole for a storage electrode; forming an undoped polysilicon layer over the entire exposed surface of the resulting structure; forming a doped polysilicon layer over said undoped polysilicon layer; and removing portions of said doped polysilicon layer and said undoped polysilicon layer by a patterning process and thereby forming a storage electrode made of two layers, said two layers consisting of said undoped polysilicon layer and said doped polysilicon layer wherein said undoped polysilicon layer has a thickness that corresponds to 40 to 50% of the thickness of said storage electrode, and wherein said doped polysilicon layer has a thickness that corresponds to 60 to 50% of the thickness of said storage electrode.
Claim 2
Independent Claim
149 words
A method for fabricating a DRAM cell, comprising the steps of: forming a MOSFET on a silicon substrate; forming an insulating layer over said MOSFET; etching a portion of said insulating layer to form a contact hole for a storage electrode; forming an undoped polysilicon layer over the entire exposed surface of the resulting structure; forming a doped polysilicon layer over said undoped polysilicon layer; and removing portions of said doped polysilicon layer and said undoped polysilicon layer by a patterning process and thereby forming a storage electrode made of two layers, said two layers consisting of said undoped polysilicon layer and said doped polysilicon layer wherein said undoped polysilicon layer has a thickness that corresponds to 40 to 50% of the thickness of said storage electrode, and wherein said doped polysilicon layer has a thickness that corresponds to 60 to 50% of the thickness of said storage electrode.
Claim 3
Dependent Claim
56 words
A method in accordance with claim 1, wherein said step of depositing said doped polysilicon layer is achieved by use of an in-situ process carried out by injecting a source gas of Si 2 H 6 and PH 3 /N 2 or a source gas of SiH 4 and PH 3 /SiH 4 in a tube.