Semiconductor memory device and method for manufacturing the same

A method for manufacturing a semiconductor memory device comprising:

• forming an insulating film over a substrate;
• forming a first conductive film over the insulating film;
• processing the first conductive film to form a hard mask;
• processing the insulating film with use of the hard mask as a mask to have a groove portion;
• processing the hard mask to form a pair of electrodes;
• forming an oxide semiconductor film which is in contact with the pair of electrodes and side surfaces of the groove portion and has a thickness value smaller than a depth value of the groove portion;
• forming a gate insulating film to cover the oxide semiconductor film;
• and
• forming a gate electrode overlapping with the oxide semiconductor film with the gate insulating film positioned therebetween and a second conductive film overlapping with one of the pair of electrodes with a dielectric film positioned therebetween,
• wherein the second conductive film includes the same material and is in the same layer as the gate electrode, and
• wherein the dielectric film includes the same material and is in the same layer as the gate insulating film.

A method for manufacturing a semiconductor memory device comprising:

• forming an insulating film over a substrate;
• processing the insulating film to have a groove portion;
• forming a first conductive film over the insulating film;
• processing the first conductive film to form a pair of electrodes separated so that the groove portion is sandwiched therebetween;
• forming an oxide semiconductor film which is in contact with the pair of electrodes and side surfaces of the groove portion and has a thickness value smaller than a depth value of the groove portion;
• forming a gate insulating film to cover the oxide semiconductor film;
• and
• forming a gate electrode overlapping with the oxide semiconductor film with the gate insulating film positioned therebetween and a second conductive film overlapping with one of the pair of electrodes with a dielectric film positioned therebetween,
• wherein the second conductive film includes the same material and is in the same layer as the gate electrode, and
• wherein the dielectric film includes the same material and is in the same layer as the gate insulating film.

A method for manufacturing a semiconductor memory device comprising:

• forming an insulating film over a substrate;
• forming a first conductive film over the insulating film;
• processing the first conductive film to form a pair of electrodes;
• processing the insulating film to have a groove portion between the pair of electrodes;
• forming an oxide semiconductor film which is in contact with the pair of electrodes and side surfaces of the groove portion and has a thickness value smaller than a depth value of the groove portion;
• forming a gate insulating film to cover the oxide semiconductor film;
• and
• forming a gate electrode overlapping with the oxide semiconductor film with the gate insulating film positioned therebetween and a second conductive film overlapping with one of the pair of electrodes with a dielectric film positioned therebetween,
• wherein the second conductive film includes the same material and is in the same layer as the gate electrode, and
• wherein the dielectric film includes the same material and is in the same layer as the gate insulating film.

A method for manufacturing a semiconductor memory device comprising:

• forming an insulating film over a substrate;
• processing the insulating film to include a first groove portion and a second groove portion;
• forming a first conductive film over the insulating film;
• processing the first conductive film to form a pair of electrodes separated so that the first groove portion is sandwiched therebetween;
• forming an oxide semiconductor film which is in contact with the pair of electrodes and side surfaces of the first groove portion and has a thickness value smaller than a depth value of the first groove portion;
• forming a gate insulating film to cover the oxide semiconductor film and one of the pair of electrodes;
• and
• forming a gate electrode overlapping with the oxide semiconductor film with the gate insulating film positioned therebetween and a second conductive film overlapping with the one of the pair of electrodes and the second groove portion with a dielectric film positioned therebetween,
• wherein the second conductive film includes the same material and is in the same layer as the gate electrode, and
• wherein the dielectric film includes the same material and is in the same layer as the gate insulating film.