Method of making semiconductor memory elements

Claim 1

A method of making a semiconductor memory element comprising the steps of: forming a field oxide film on a semiconductor substrate to define an active region in the semiconductor substrate; forming a transistor at the active region, the transistor having a gate oxide film, a gate, source and drain regions and a gate insulating film; etching the gate insulating film to form a bit line contact with the source region; forming a polysilicon film, a metal silicide film and a first oxide film, in this order, on the exposed surface, and patterning the polysilicon film, the metal silicide film and the first oxide film to form a bit line connected to the source region through the bit line contact; forming a second oxide film on the exposed surface and anisotropically dry etching the second oxide film to form side wall spacers for the bit line and to form a capacitor contact with the drain region; depositing a first doped polysilicon film for a storage node on the exposed surface, the first doped polysilicon film being connected with the drain region of the transistor through the capacitor contact; forming a first smoothing oxide film on the first doped polysilicon film and etching back the first smoothing oxide film to smooth the surface thereof; etching the first smoothing oxide film to expose portions of the first doped polysilicon film disposed over the bit line and the field oxide film; etching the exposed portions of the first doped polysilicon film; forming a nitride film on the exposed surface; forming a second smoothing oxide film on the nitride film and etching back the second smoothing oxide film to smooth the surface thereof and to expose partially the nitride film; etching the exposed portion of the nitride film; depositing a second doped polysilicon film for the storage node on the exposed surface; forming a third smoothing oxide film on the second doped polysilicon film and etching back the third smoothing oxide film to smooth the surface thereof and to expose partially the second doped polysilicon film; etching the exposed portion of the second doped polysilicon film, wherein portions of the second doped polysilicon film remain and are connected to the remaining portions of the first doped polysilicon layer; removing the remaining portions of the first and third smoothing oxide films to form the storage node; forming a dielectric film for a capacitor on the exposed surface; and forming a plate node on the dielectric film.

Claim 2

A method of making a semiconductor memory element comprising the steps of: forming a field oxide film on a semiconductor substrate to define an active region in the semiconductor substrate; forming a transistor at the active region, the transistor having a gate oxide film, a gate, source and drain regions and a gate insulating film; etching the gate insulating film to form a bit line contact with the source region; forming a polysilicon film, a metal silicide film and a first oxide film, in this order, on the exposed surface, and patterning the polysilicon film, the metal silicide film and the first oxide film to form a bit line connected to the source region through the bit line contact; forming a second oxide film on the exposed surface and anisotropically dry etching the second oxide film to form side wall spacers for the bit line and to form a capacitor contact with the drain region; depositing a first doped polysilicon film for a storage node on the exposed surface, the first doped polysilicon film being connected with the drain region of the transistor through the capacitor contact; forming a first smoothing oxide film on the first doped polysilicon film and etching back the first smoothing oxide film to smooth the surface thereof; etching the first smoothing oxide film to expose portions of the first doped polysilicon film disposed over the bit line and the field oxide film; etching the exposed portions of the first doped polysilicon film; forming a nitride film on the exposed surface; forming a second smoothing oxide film on the nitride film and etching back the second smoothing oxide film to smooth the surface thereof and to expose partially the nitride film; etching the exposed portion of the nitride film; depositing a second doped polysilicon film for the storage node on the exposed surface; forming a third smoothing oxide film on the second doped polysilicon film and etching back the third smoothing oxide film to smooth the surface thereof and to expose partially the second doped polysilicon film; etching the exposed portion of the second doped polysilicon film, wherein portions of the second doped polysilicon film remain and are connected to the remaining portions of the first doped polysilicon layer; removing the remaining portions of the first and third smoothing oxide films to form the storage node; forming a dielectric film for a capacitor on the exposed surface; and forming a plate node on the dielectric film.

Claim 11

A method of making a semiconductor memory element comprising the steps of: forming a field oxide film on a semiconductor substrate to define an active region in the semiconductor substrate; forming a transistor at the active region, the transistor having a gate oxide film, a gate, source and drain regions and a gate insulating film; etching the gate insulating film to form a bit line contact with the source region; forming a polysilicon film, a metal silicide film and a first oxide film, in this order, on the exposed surface, and patterning the polysilicon film, the metal silicide film and the first oxide film to form a bit line connected to the source region through the bit line contact; forming a second oxide film on the exposed surface, and anisotropically dry etching the second oxide film to form side wall spacers for the bit line and to form a capacitor contact with the drain region; depositing a first doped polysilicon film for a storage node on the exposed surface, the first doped polysilicon film being connected with the drain region of the transistor through the capacitor contact; forming a first smoothing oxide film on the first doped polysilicon film and etching back the first smoothing oxide film to smooth the surface thereof; etching the first smoothing oxide film to expose portions of the first doped polysilicon film disposed over the bit line and the field oxide film; etching the exposed portions of the first doped polysilicon film using the first smoothing oxide film as a mask; forming a nitride film on the exposed surface; forming a second smoothing oxide film on the nitride film and etching back the second smoothing oxide film to smooth the surface thereof and to expose partially the nitride film; etching the exposed portion of the nitride film; depositing a second doped polysilicon film for the storage node on the exposed surface; etching the exposed portion of the second doped polysilicon film, wherein portions of the second doped polysilicon film remain and are connected to the remaining portions of the first doped polysilicon layer; etching the remaining portions of the first and second smoothing oxide films to form the storage node; forming a dielectric film for a capacitor on the exposed surface; and forming a plate node on the dielectric film.

Claim 12

A method of making a semiconductor memory element comprising the steps of: forming a field oxide film on a semiconductor substrate to define an active region in the semiconductor substrate; forming a transistor at the active region, the transistor having a gate oxide film, a gate, source and drain regions and a gate insulating film; etching the gate insulating film to form a bit line contact with the source region; forming a polysilicon film, a metal silicide film and a first oxide film, in this order, on the exposed surface, and patterning the polysilicon film, the metal silicide film and the first oxide film to form a bit line connected to the source region through the bit line contact; forming a second oxide film on the exposed surface, and anisotropically dry etching the second oxide film to form side wall spacers for the bit line and to form a capacitor contact with the drain region; depositing a first doped polysilicon film for a storage node on the exposed surface, the first doped polysilicon film being connected with the drain region of the transistor through the capacitor contact; forming a first smoothing oxide film on the first doped polysilicon film and etching back the first smoothing oxide film to smooth the surface thereof; etching the first smoothing oxide film to expose portions of the first doped polysilicon film disposed over the bit line and the field oxide film; etching the exposed portions of the first doped polysilicon film using the first smoothing oxide film as a mask; forming a nitride film on the exposed surface; forming a second smoothing oxide film on the nitride film and etching back the second smoothing oxide film to smooth the surface thereof and to expose partially the nitride film; etching the exposed portion of the nitride film; depositing a second doped polysilicon film for the storage node on the exposed surface; etching the exposed portion of the second doped polysilicon film, wherein portions of the second doped polysilicon film remain and are connected to the remaining portions of the first doped polysilicon layer; etching the remaining portions of the first and second smoothing oxide films to form the storage node; forming a dielectric film for a capacitor on the exposed surface; and forming a plate node on the dielectric film.