Nonvolatile semiconductor memory device and method for fabricating the same

A method for fabricating a nonvolatile semiconductor memory device, the method comprising:

• a control-gate-electrode forming step of forming a first insulating film on a semiconductor substrate, patterning a conductor film formed on the first insulating film, and thereby forming a control gate electrode from the conductor film;
• a second-insulating-film depositing step of depositing a second insulating film over the entire surface of the semiconductor substrate including the control gate electrode;
• a sidewall forming step of forming sidewalls over the first insulating film and on portions of the second insulating film located on side surfaces of the control gate electrode;
• a protective-insulating-film forming step of performing etching with respect to the first and second insulating films by using the sidewalls and the control gate electrode as a mask and thereby forming, from the second insulating film, a protective insulating film for protecting the control gate electrode on each of the side surfaces of the control gate electrode, while forming, from the first insulating film, a gate insulating film under the control gate electrode;
• a tunnel-insulating-film forming step of removing the sidewalls and then forming, in a region in which the semiconductor substrate is exposed, a third insulating film serving as a tunnel insulating film;
• a floating-gate-electrode forming step of forming by self alignment a floating gate electrode capacitively coupled to one of the side surfaces of the control gate electrode with the protective insulating film interposed therebetween and opposed to the semiconductor substrate with the tunnel insulating film interposed therebetween;
• and
• a source/drain forming step of implanting an impurity into the semiconductor substrate by using the control gate electrode and the floating gate electrode as a mask and thereby forming a source region and a drain region in the semiconductor substrate.

A method for fabricating a nonvolatile semiconductor memory device, the method comprising:

• a control-gate-electrode forming step of forming a first insulating film on a semiconductor substrate, patterning a conductor film formed on the first insulating film, and thereby forming a control gate electrode from the conductor film;
• a second-insulating-film depositing step of depositing a second insulating film over the entire surface of the semiconductor substrate including the control gate electrode;
• a protective-insulating-film forming step of selectively removing the second insulating film so as to leave a portion of the second insulating film located on one of side surfaces of the control gate electrode and thereby forming, from the second insulating film, a protective insulating film for protecting the one of the side surfaces of the control gate electrode;
• a gate-insulating-film forming step of selectively removing the first insulating film so as to leave a portion of the first insulating film underlying the control gate electrode and thereby forming a gate insulating film from the first insulating film;
• a tunnel-insulating-film forming step of forming, on the semiconductor substrate, a third insulating film serving as a tunnel insulating film;
• a floating-gate-electrode forming step of forming by self alignment a floating gate electrode capacitively coupled to the side surface of the control gate electrode with the protective insulating film interposed therebetween and opposed to the semiconductor substrate with the tunnel insulating film interposed therebetween;
• and
• a source/drain forming step of implanting an impurity into the semiconductor substrate by using the control gate electrode and the floating gate electrode as a mask and thereby forming a source region and a drain region in the semiconductor substrate.

A method for fabricating a nonvolatile semiconductor memory device, the method comprising:

• a control-gate-electrode forming step of forming a first insulating film on a semiconductor substrate, patterning a conductor film formed on the first insulating film, and thereby forming a control gate electrode from the conductor film;
• a second-insulating-film depositing step of depositing a second insulating film over the entire surface of the semiconductor substrate including the control gate electrode;
• a sidewall forming step of forming sidewalls over the first insulating film and on portions of the second insulating film located on side surfaces of the control gate electrode;
• a protective-insulating-film forming step of performing etching with respect to the first and second insulating films by using the sidewalls and the control gate electrode as a mask and thereby forming, from the second insulating film, a protective insulating film for protecting the control gate electrode on each of the side surfaces of the control gate electrode, while forming, from the first insulating film, a gate insulating film under the control gate electrode;
• a protective-insulating-film removing step of removing the sidewalls and then selectively removing the protective insulating film so as to leave a portion of the protective insulating film located on one of the side surfaces of the control gate electrode;
• a tunnel-insulating-film forming step of forming, in a region in which the semiconductor substrate is exposed, a third insulating film serving as a tunnel insulating film;
• a floating-gate-electrode forming step of forming by self alignment a floating gate electrode capacitively coupled to the side surface of the control gate electrode with the protective insulating film interposed therebetween and opposed to the semiconductor substrate with the tunnel insulating film interposed therebetween;
• and
• a source/drain forming step of implanting an impurity into the semiconductor substrate by using the control gate electrode and the floating gate electrode as a mask and thereby forming a source region and a drain region in the semiconductor substrate.

A method for fabricating a nonvolatile semiconductor memory device, the method comprising:

• a control-gate-electrode forming step of forming a first insulating film on a semiconductor substrate, patterning a conductor film formed on the first insulating film, and thereby forming a control gate electrode from the conductor film;
• a second-insulating-film depositing step of depositing a second insulating film over the entire surface of the semiconductor substrate including the control gate electrode;
• a protective-insulating-film forming step of selectively removing the second insulating film so as to leave a portion of the second insulating film located on that one of the side surfaces of the control gate electrode opposite to the side surface to be formed with a floating gate electrode and thereby forming, from the second insulating film, a protective insulating film for protecting the control gate electrode;
• a gate-insulating-film forming step of selectively removing the first insulating film so as to remove a portion of the first insulating film underlying the control gate electrode and thereby forming a gate insulating film from the first insulating film;
• a capacitance-insulating-film forming step of forming a capacitance insulating film on that one of the side surfaces of the control gate electrode to be formed with the floating gate electrode;
• a tunnel-insulating-film forming step of forming a tunnel insulating film on the semiconductor substrate;
• a floating-gate-electrode forming step of forming by self alignment the floating gate electrode capacitively coupled to the side surface of the control gate electrode with the capacitance insulating film interposed therebetween and opposed to the semiconductor substrate with the tunnel insulating film interposed therebetween;
• and
• a source/drain forming step of implanting an impurity into the semiconductor substrate by using the control gate electrode and the floating gate electrode as a mask and thereby forming a source region and a drain region in the semiconductor substrate.

A method for fabricating a nonvolatile semiconductor memory device, the method comprising:

• a control-gate-electrode forming step of forming a first insulating film on a semiconductor substrate, patterning a conductor film formed on the first insulating film, and thereby forming a control gate electrode from the conductor film;
• a second-insulating-film depositing step of depositing a second insulating film over the entire surface of the semiconductor substrate including the control gate electrode;
• a sidewall forming step of forming sidewalls over the first insulating film and on portions of the second insulating film located on side surfaces of the control gate electrode;
• a protective-insulating-film forming step of performing etching with respect to the first and second insulating films by using the sidewalls and the control gate electrode as a mask and thereby forming, from the second insulating film, a protective insulating film for protecting the control gate electrode on each of the side surfaces of the control gate electrode, while forming, from the first insulating film, a gate insulating film under the control gate electrode;
• a protective-insulating-film removing step of removing the sidewalls and then selectively removing a portion of the protective insulating film located on that one of the side surfaces of the control gate electrode to be formed with a floating gate electrode;
• a capacitance-insulating-film forming step of forming a capacitance insulating film on the side surface of the control gate electrode to be formed with the floating gate electrode;
• a tunnel-insulating-film forming step of forming a tunnel insulating film in a region in which the semiconductor substrate is exposed;
• a floating-gate-electrode forming step of forming by self alignment the floating gate electrode capacitively coupled to the side surface of the control gate electrode with the capacitance insulating film interposed therebetween and opposed to the semiconductor substrate with the tunnel insulating film interposed therebetween;
• and
• a source/drain forming step of implanting an impurity into the semiconductor substrate by using the control gate electrode and the floating gate electrode as a mask and thereby forming a source region and a drain region in the semiconductor substrate.