Semiconductor device and manufacturing method thereof
Provided is an in-wiring-layer active element (component) which allows for electrical isolation between a gate electrode and a channel in a top gate structure. A semiconductor device includes a first wiring layer, a second wiring layer, and a semiconductor element. The first wiring layer has a first interlayer insulating layer, and a first wire embedded in the first interlayer insulating layer. The second wiring layer has a second interlayer insulating layer, and second wires embedded in the second interlayer insulating layer. The semiconductor element is provided at least in the second wiring layer. The semiconductor element includes a semiconductor layer provided in the second wiring layer, a gate insulating film provided in contact with the semiconductor layer, a gate electrode provided on the opposite side of the semiconductor layer via the first gate insulating film, and a first side wall film provided over a side surface of the semiconductor layer.
1. A method of manufacturing a semiconductor device, comprising steps of:
(a) forming a first wiring over a semiconductor substrate;
(b) forming a first insulating film over the first wiring:
(c) forming a semiconductor layer over the first insulating film;
(d) forming a first gate insulating film over the semiconductor layer;
(e) patterning the first gate insulating film;
(f) after the step (e), patterning the semiconductor layer by using the first gate insulating film as a mask;
(g) after the step (f), forming a first side wall which is made of a second insulating film, over a side surface of the semiconductor layer so as to surround the semiconductor layer in a plan view;
(h) forming a first gate electrode over the first gate insulating film, the first side wall and the first insulating film;
(i) patterning the first gate electrode such that the first gate insulating film is exposed from the first gate electrode in a gate length direction;
(j) after the step (i), forming a third insulating film over the first gate electrode, the first gate insulating film, the first side wall and the first insulating film; and
(k) forming a first contact for a drain electrode and a second contact for a source electrode in the third insulating film and the first gate insulating film in order to be connected to the semiconductor layer,
wherein, after the step (i), as considered in a gate width direction, the first gate electrode is located over the first gate insulating film, the first side wall, and parts of the first insulating film disposed to opposite sides of the semiconductor layer in a region surrounding the semiconductor layer and the first sidewall in the plan view, and
wherein, in the gate width direction in the plan view, the first side wall has portions located between the side surface of the semiconductor layer and portions of the first gate electrode formed over the parts of the first insulating film.
2. A method of manufacturing a semiconductor device according to claim 1 , wherein, in the step (e), the first gate insulating film is patterned by using a resist film, and wherein the resist film is removed before the step (f).
3. A method of manufacturing a semiconductor device according to claim 2 , wherein the first side wall is also formed over a side surface of the first gate insulating film.
4. A method of manufacturing a semiconductor device according to claim 3 , wherein the semiconductor layer includes an InGaZnO layer, an InZnO layer, a ZnO layer, a ZnAlO layer, a ZnCuO layer, an NiO layer, an SnO layer, an SnO 2 layer, a CuO layer or a Cu 2 O layer.
5. A method of manufacturing a semiconductor device according to claim 4 , wherein the first gate insulating film includes a silicon oxide film, a silicon nitride film or an oxide film of Hf, Zr, Al or Ta.
6. A method of manufacturing a semiconductor device according to claim 5 , wherein the second insulating film is made of a different material from the first gate insulating film.