SEMICONDUCTOR DEVICE HAVING VERTICAL TRANSISTOR
Disclosed herein is a device that includes: a semiconductor substrate; a first semiconductor pillar having a side surface that is substantially perpendicular to a main surface of the semiconductor substrate; an insulator pillar having a side surface that is substantially perpendicular to the main surface of the semiconductor substrate and a top surface that is substantially parallel to the main surface of the semiconductor substrate; a first gate electrode covering the side surface of the first semiconductor pillar with intervention of a first gate insulation film; an extended gate electrode covering the side surface of the insulator pillar, the extended gate electrode being configured integrally with the first gate electrode; and a conductive film formed on the top surface of the insulator pillar, the conductive film being in contact with the extended gate electrode in a position above the top surface of the insulator pillar.
1 . A semiconductor device comprising:
a semiconductor substrate having a main surface;
a first semiconductor pillar having a side surface that is substantially perpendicular to the main surface of the semiconductor substrate;
an insulator pillar having a side surface that is substantially perpendicular to the main surface of the semiconductor substrate and a top surface that is substantially parallel to the main surface of the semiconductor substrate;
a first gate electrode covering the side surface of the first semiconductor pillar with an intervention of a first gate insulation film;
an extended gate electrode covering the side surface of the insulator pillar, the extended gate electrode being contacted with the first gate electrode; and
a conductive film formed on the top surface of the insulator pillar, the conductive film being in contact with the extended gate electrode in a position above the top surface of the insulator pillar.
2 . The semiconductor device as claimed in claim 1 , wherein the conductive film comprises a metal material.
3 . The semiconductor device as claimed in claim 2 , wherein the conductive film comprises a stacked film having a first barrier layer and the metal material stacked on the first barrier layer.
4 . The semiconductor device as claimed in claim 2 , wherein the metal material comprises tungsten.
5 . The semiconductor device as claimed in claim 1 , wherein the conductive film is lower in resistivity than an impurity-doped silicon film.
6 . The semiconductor device as claimed in claim 1 , wherein the conductive film is configured to be in contact with the extended gate electrode around an entire circumference of the top surface of the insulator pillar.
7 . The semiconductor device as claimed in claim 1 , wherein each of the first gate electrode and the extended gate electrode comprises a stacked film having a second barrier layer and a polysilicon stacked on the second barrier layer.
8 . The semiconductor device as claimed in claim 1 , further comprising:
an interlayer insulation film formed on the main surface of the semiconductor substrate so as to cover the first semiconductor pillar, the insulator pillar, the first gate electrode, the extended gate electrode, and the conductive film;
a lower diffusion layer formed in contact with a lower portion of the first semiconductor pillar;
an upper diffusion layer formed in contact with an upper portion of the first semiconductor pillar;
a first contact plug penetrating through the interlayer insulation film and electrically connected to the lower diffusion layer;
a second contact plug penetrating through the interlayer insulation film and electrically connected to the upper diffusion layer; and
a third contact plug penetrating through the interlayer insulation film to contact with at least either one of the extended gate electrode and the conductive film.
9 . The semiconductor device as claimed in claim 8 , wherein
the conductive film is also formed on a top surface of the upper diffusion layer, and
the second contact plug is in electrical contact with the upper diffusion layer through the conductive film.
10 . The semiconductor device as claimed in claim 8 , wherein the first contact plug includes a cobalt silicide film, and is in contact with the lower diffusion layer through the cobalt silicide film.
11 . The semiconductor device as claimed in claim 1 , further comprising:
a second semiconductor pillar having a side surface that is substantially perpendicular to the main surface of the semiconductor substrate; and
a second gate electrode covering the side surface of the second semiconductor pillar with an intervention of a second gate insulation film, wherein
the insulator pillar is arranged between the first and second semiconductor pillars, and
the extended gate electrode is contacted with the first and second gate electrodes.
12 . The semiconductor device as claimed in claim 11 , wherein
the main surface of the semiconductor substrate includes first and second active regions that are defined by respective element isolation regions,
the first semiconductor pillar is formed in the first active region, and
the second semiconductor pillar is formed in the second active region.
13 . The semiconductor device as claimed in claim 11 , wherein
the main surface of the semiconductor substrate includes a third active region that is defined by an element isolation region, and
the first and second semiconductor pillars are both formed in the third active region.
14 . The semiconductor device as claimed in claim 7 , wherein the second barrier layer is in direct contact with the first barrier layer.
15 . The semiconductor device as claimed in claim 8 , wherein the upper diffusion layer is electrically isolated from the first gate electrode and the extended gate electrode by a sidewall insulation film.
16 . The semiconductor device as claimed in claim 9 , wherein
the conductive film formed on the top surface of the insulator pillar has a first top surface,
the conductive film formed on the top surface of the upper diffusion layer has a second top surface, and
the first and second top surfaces are substantially coplanar.
17 . The semiconductor device as claimed in claim 9 , wherein the conductive film formed on the top surface of the upper diffusion layer and the conductive film formed on the top surface of the insulator pillar are made of the same material.
18 . The semiconductor device as claimed in claim 11 , wherein
the first semiconductor pillar and the insulator pillar are arranged on a first straight line, and
the second semiconductor pillar and the insulator pillar are arranged on a second straight line different from the first straight line.
19 . A semiconductor device comprising:
a semiconductor substrate having a main surface;
a plurality of first semiconductor pillars arranged in a first direction, each of the first semiconductor pillars having a side surface that is substantially perpendicular to the main surface of the semiconductor substrate;
a plurality of second semiconductor pillars arranged in the first direction, each of the second semiconductor pillars having a side surface that is substantially perpendicular to the main surface of the semiconductor substrate;
a plurality of insulator pillars each arranged between an associated one of the first semiconductor pillars and an associated one of the second semiconductor pillars, each of the insulator pillars having a side surface that is substantially perpendicular to the main surface of the semiconductor substrate and a top surface that is substantially parallel to the main surface of the semiconductor substrate;
a plurality of first gate electrodes each covering the side surface of each of the first semiconductor pillars with an intervention of a first gate insulation film;
a plurality of second gate electrodes each covering the side surface of each of the second semiconductor pillars with an intervention of a second gate insulation film;
a plurality of extended gate electrodes each covering the side surface of each of the insulator pillars, the extended gate electrode being contacted with the first and second gate electrodes;
a plurality of conductive films each formed on the top surface of an associated one of the insulator pillars, the conductive films being in contact with the extended gate electrode in a position above the top surface of each of the insulator pillars;
a plurality of first upper diffusion layers each formed in contact with an upper portion of an associated one of the first semiconductor pillars;
a plurality of second upper diffusion layers each formed in contact with an upper portion of an associated one of the second semiconductor pillars;
a first wiring extending in the first direction and connected in common to the first upper diffusion layers;
a second wiring extending in the first direction and connected in common to the second upper diffusion layers;
a third wiring connected between the first and second wirings; and
a fourth wiring extending in the first direction and connected in common to the conductive films.
20 . The semiconductor device as claimed in claim 19 , wherein
the main surface of the semiconductor substrate includes an active region defined by an element isolation region, and
the first and second semiconductor pillars are both formed in the active region.