Method for forming cylindrical capacitor lower plate in semiconductor device

Claim 1

A method for forming a lower plate of a cylinder type stacked structure capacitor in a semiconductor device, comprising: depositing a first insulating film on a principal surface of a semiconductor substrate in which at least one MOS transistor is formed; forming a contact hole which penetrates said first insulating film to reach said semiconductor substrate; depositing a first conducting film to fill said contact hole and to cover said first insulating film; depositing on said first conducting film, a second insulating film which is formed of a silicon oxide film containing at least one impurity selected from the group consisting of V-group elements and III-group elements, and which can be selectively etched against said first insulating film; conducting a heat treatment after said second insulating film is deposited; forming a resist film on said second insulating film and at a position directly above said contact hole; conducting a first anisotropic etching using said photoresist film as a mask, so as to selectively etch said second insulating film, thereby to deposit an etching reaction product and to form a patterned second insulating film in alignment with said resist film; removing said reaction product deposited and said resist film; etching selectively said first conducting film using said patterned film as a mask, to form a patterned first conducting film in alignment with said patterned second insulating film, and to expose said first insulating film; depositing a second conducting film on a whole surface; conducting a second anisotropic etching to said second conducting film so that a remaining second conducting film is left only on a side surface of said patterned second insulating film and said patterned first conducting film thereunder, said remaining second conducting film being in contact with said patterned first conducting film; and selectively removing said patterned second insulating film, whereby said patterned first conducting film constitutes a base portion of a cylindrical capacitor lower plate, and said remaining second conducting film constitutes a sidewall portion of said cylindrical capacitor lower plate, said sidewall portion being upright from a periphery of said base portion.

Claim 2

A method for forming a lower plate of a cylinder type stacked structure capacitor in a semiconductor device, comprising: depositing a first insulating film on a principal surface of a semiconductor substrate in which at least one MOS transistor is formed; forming a contact hole which penetrates said first insulating film to reach said semiconductor substrate; depositing a first conducting film to fill said contact hole and to cover said first insulating film; depositing on said first conducting film, a second insulating film which is formed of a silicon oxide film containing at least one impurity selected from the group consisting of V-group elements and III-group elements, and which can be selectively etched against said first insulating film; conducting a heat treatment after said second insulating film is deposited; forming a resist film on said second insulating film and at a position directly above said contact hole; conducting a first anisotropic etching using said photoresist film as a mask, so as to selectively etch said second insulating film, thereby to deposit an etching reaction product and to form a patterned second insulating film in alignment with said resist film; removing said reaction product deposited and said resist film; etching selectively said first conducting film using said patterned film as a mask, to form a patterned first conducting film in alignment with said patterned second insulating film, and to expose said first insulating film; depositing a second conducting film on a whole surface; conducting a second anisotropic etching to said second conducting film so that a remaining second conducting film is left only on a side surface of said patterned second insulating film and said patterned first conducting film thereunder, said remaining second conducting film being in contact with said patterned first conducting film; and selectively removing said patterned second insulating film, whereby said patterned first conducting film constitutes a base portion of a cylindrical capacitor lower plate, and said remaining second conducting film constitutes a sidewall portion of said cylindrical capacitor lower plate, said sidewall portion being upright from a periphery of said base portion.