Semiconductor device and method for fabricating the same
A semiconductor device has, on a single substrate, a semiconductor circuit portion and a hollow capacitor portion including a pair of counter electrodes and a hollow part located between the counter electrodes. The hollow part of the hollow capacitor portion is surrounded by an insulating film, and a through hole is formed in the insulating film to communicate with the hollow part. The top surface of the insulating film covering the hollow part is planarized. Part of the insulating film located to the lateral sides of the hollow part supports the other part thereof located on the hollow part and upper one of the counter electrodes.
1 . A semiconductor device comprising, on a single substrate, a semiconductor circuit portion and a hollow capacitor portion including a pair of counter electrodes and a hollow part located between the counter electrodes,
the hollow part of the hollow capacitor portion being surrounded by an insulating film.
2 . The semiconductor device of claim 1 , wherein
the insulating film includes:
a first insulating film covering lower one of the counter electrodes of the hollow capacitor portion;
a second insulating film covering the hollow part of the hollow capacitor portion formed on the first insulating film; and
a third insulating film covering upper one of the counter electrodes formed on the second insulating film.
3 . The semiconductor device of claim 2 , wherein
a first hole is formed to pass through the third insulating film and the second insulating film and reach the hollow part.
4 . The semiconductor device of claim 2 , wherein
a second hole is formed to pass through at least the third insulating film and the upper one of the counter electrodes and reach the hollow part.
5 . The semiconductor device of claim 4 , wherein
the wall of the second hole is covered with a protective film.
6 . The semiconductor device of claim 5 , wherein
the insulating film and the protective film are made of silicon oxide,
the counter electrodes of the hollow capacitor portion are made of polycrystalline silicon, and
the upper one of the counter electrodes is vertically interposed between silicon nitride films.
7 . The semiconductor device of claim 1 further comprising
a charge retention layer between upper one of the counter electrodes and the hollow part,
the charge retention layer being surrounded by the insulating film.
8 . The semiconductor device of claim 7 , wherein
the insulating film includes:
a first insulating film covering lower one of the counter electrodes of the hollow capacitor portion;
a second insulating film covering the hollow part of the hollow capacitor portion formed on the first insulating film; and
a fourth insulating film covering the charge retention layer formed on the second insulating film, and
the upper one of the counter electrodes of the hollow capacitor portion is formed on the fourth insulating film.
9 . The semiconductor device of claim 8 , wherein
a first hole is formed to pass through at least the second insulating film and reach the hollow part.
10 . A semiconductor device comprising:
a hollow capacitor including a fixed electrode formed on a substrate, a hollow part and a movable electrode;
a first insulating film covering the substrate and the fixed electrode; and
a second insulating film covering the first insulating film and the hollow part,
the hollow part being formed on a part of the first insulating film located on the fixed electrode, the movable electrode being formed on a part of the second insulating film located on the hollow part, and the top surface of the second insulating film being planarized.
11 . The semiconductor device of claim 10 further comprising
a third insulating film covering the second insulating film and the movable electrode.
12 . The semiconductor device of claim 11 , wherein
a through hole is formed in the second and third insulating films to reach the hollow part.
13 . The semiconductor device of claim 12 , wherein
the hollow part has one or more linking passageways horizontally extending from one or more associated ends of the hollow part toward the second insulating film, and
the through hole reaches the linking passageways.
14 . The semiconductor device of claim 13 , wherein
the hollow part is rectangular, and
the linking passageways horizontally extend from the ends of the hollow part toward the second insulating film such that the hollow part and the linking passageways form the shape of a cross.
15 . The semiconductor device of claim 13 or 14 , wherein
an end part of the movable electrode is located on each said linking passageway.
16 . A method for fabricating a semiconductor device, said method comprising the steps of:
forming a fixed electrode on a substrate;
forming a first insulating film to cover the substrate and, the fixed electrode;
forming a sacrificial layer on part of the first insulating film located on the fixed electrode;
forming a second insulating film to cover the first insulating film and the sacrificial layer;
planarizing the top surface of the second insulating film such that a part of the second insulating film left on the sacrificial layer has a predetermined thickness;
forming a movable electrode on a part of the second insulating film located on the sacrificial layer;
forming a third insulating film to cover the second insulating film and the movable electrode;
forming a through hole to pass through the second and third insulating films and reach the sacrificial layer; and
etching away the sacrificial layer through the through hole, thereby forming a hollow part in the second insulating film,
wherein the fixed electrode, the hollow part and the movable electrode form a hollow capacitor.
17 . The method of claim 16 , wherein
the sacrificial layer has a portion horizontally extending from an end of the sacrificial layer toward the second insulating film, and
the through hole reaches the extending portion of the sacrificial layer.