Semiconductor device including dummy pillar near intermediate portion of semiconductor pillar group

A semiconductor device comprising:

• a first semiconductor pillar group comprising first through N-th semiconductor pillars which are formed in a first direction with a space left therebetween, where N represents a positive integer which is not less than three;
• a second semiconductor pillar group adjacent to the first semiconductor pillar group, the second semiconductor pillar group comprising (N+1)-th through 2N-th semiconductor pillars which are formed in the first direction with a space left therebetween;
• a first dummy pillar disposed near a first particular semiconductor pillar in the first semiconductor pillar group in a second direction perpendicular to the first direction, the first particular semiconductor pillar being any one of the second through the (N−1)-th semiconductor pillars which are positioned in an intermediate portion exclusive of the first and the N-th semiconductor pillars;
• a second dumpy pillar disposed near a second particular semiconductor pillar in the second semiconductor pillar group in the second direction at an opposite side of the first dummy pillar, the second particular semiconductor pillar being any one of the (N+2)-th through the (2N−1)-th semiconductor pillars which are positioned in an intermediate portion exclusive to the (N+1)-th and the 2N-th semiconductor pillars;
• gate insulating films which are formed on outer circumferential surfaces of the first through the 2N-th semiconductor pillars and two of which are formed on parts of outer circumferential surfaces of the first and the second dummy pillars;
• and
• gate electrodes which are formed over side faces of the first through the 2N-th semiconductor pillars and two of which are formed over side faces of the first and the second dumpy pillars via the gate insulating films so as to fill gaps between the first through the 2N-th semiconductor pillars, a gap between the first particular semiconductor pillar and the first dumpy pillar, and a gap between the second particular semiconductor pillar and the second dummy pillar.

A semiconductor device comprising:

• a first semiconductor pillar group comprising first through N-th semiconductor pillars which are formed in a first direction with a space left therebetween, where N represents a positive integer which is not less than three;
• a second semiconductor pillar group adjacent to the first semiconductor pillar group, the second semiconductor pillar group comprising (N+1)-th through 2N-th semiconductor pillars which are formed in the first direction with a space left therebetween;
• a first dummy pillar disposed near a first particular semiconductor pillar in the first semiconductor pillar group in a second direction perpendicular to the first direction, the first particular semiconductor pillar being any one of the second through the (N−1)-th semiconductor pillars which are positioned in an intermediate portion exclusive of the first and the N-th semiconductor pillars;
• a second dumpy pillar disposed near a second particular semiconductor pillar in the second semiconductor pillar group in the second direction at an opposite side of the first dummy pillar, the second particular semiconductor pillar being any one of the (N+2)-th through the (2N−1)-th semiconductor pillars which are positioned in an intermediate portion exclusive to the (N+1)-th and the 2N-th semiconductor pillars;
• gate insulating films which are formed on outer circumferential surfaces of the first through the 2N-th semiconductor pillars and two of which are formed on parts of outer circumferential surfaces of the first and the second dummy pillars;
• first gate electrodes which are formed over side faces of the first through the N-th semiconductor pillars and one of which is formed over a side face of the first dumpy pillar via the gate insulating films so as to fill gaps between the first through the N-th semiconductor pillars and a gap between the first particular semiconductor pillar and the first dumpy pillar;
• and
• second gate electrodes which are formed over side faces of the (N+1)-th through the 2N-th semiconductor pillars and one of which is formed over a side face of the second dumpy pillar via the gate insulating films so as to fill gaps between the (N+1)-th through the 2N-th semiconductor pillars and a gap between the second particular semiconductor pillar and the second dummy pillar,
• wherein the interval between the first semiconductor pillar group and the second semiconductor pillar group is more double the thickness of each gate electrode.