Nonvolatile semiconductor device and method of manufacturing the same

Claim 1

A nonvolatile semiconductor device made up of a plurality of semiconductor elements, each of which comprises: a semiconductor substrate (101) of a first conductivity type; a source region (104) and a drain region (102) which are formed in a surface region of the semiconductor substrate (101) and have a second conduc­tivity type; a first gate electrode (108) formed above a channel region (105) between the source and drain regions (104, 102) and kept in an electrically-floating state by a first gate insulation film (107); and a sec­ond gate electrode (110) serving as a control gate and formed above the first gate electrode (108), with a sec­ond gate insulation film (109) interposed, said source and drain regions (104, 102) being formed under a third insulation film (106) which is thicker than the first gate insulation film (107) and which isolates the chan­nel region (105) of one semiconductor element from that of an adjacent one, and said source and drain regions (104, 102) being located under the third insulation film (106) and separated from each other at a position corre­sponding to an end portion of the first gate electrode.

Claim 11

A method of manufacturing a nonvolatile semi­conductor device, characterized by comprising the steps of: forming embedded layers (100) of a second conduc­tivity type in a semiconductor substrate (101) of a first conductivity type; forming a channel region (105) between the embedded layers (100) by ion implantation, and then forming a first gate insulation film (107) on the channel region (105); forming an insulation film (106) wl:ich is thicker than the first gate insulation film (107) and located on the embedded layer (100); forming a first gate electrode (108) above the channel region (105) such that the first gate electrode (108) is kept in an electrically floating condition by the first gate insulation film (107), said first gate electrode (108) being formed for each element; forming a trench (103) which extends through the insulation film (106) and the embedded layer (100) and reaches the interior of the semiconductor substrate (101), thereby dividing the embedded layer (100) into a source region (104) and a drain region (102); filling the trench (103) with an insulating mate­rial (106), thereby insulating and isolating one element from an adjacent one; forming a second insulation film (109) over the resultant semiconductor structure; and forming a second gate electrode (110) on the first gate electrode (108), the insulation film (106), and the trench (103), so as to electrically connect one element to the adjacent one.

Claim 12

A method of manufacturing a nonvolatile semi­conductor device, characterized by comprising the steps of: forming embedded layers (100) of a second conduc­tivity type in a semiconductor substrate (101) of a first conductivity type; forming a channel region (105) between the embedded layers (100) by ion implantation, and then forming a first gate insulation film (107) on the channel region (105); forming an insulation film (106) wl:ich is thicker than the first gate insulation film (107) and located on the embedded layer (100); forming a first gate electrode (108) above the channel region (105) such that the first gate electrode (108) is kept in an electrically floating condition by the first gate insulation film (107), said first gate electrode (108) being formed for each element; forming a trench (103) which extends through the insulation film (106) and the embedded layer (100) and reaches the interior of the semiconductor substrate (101), thereby dividing the embedded layer (100) into a source region (104) and a drain region (102); filling the trench (103) with an insulating mate­rial (106), thereby insulating and isolating one element from an adjacent one; forming a second insulation film (109) over the resultant semiconductor structure; and forming a second gate electrode (110) on the first gate electrode (108), the insulation film (106), and the trench (103), so as to electrically connect one element to the adjacent one.