Semiconductor device and fabrication method therefor

Abstract

A semiconductor device has an interlayer insulating film formed on a substrate and a plurality of capacitors formed in directions of columns on the interlayer insulating film. Each of the capacitors has a lower electrode, a capacitor insulating film, and an upper electrode which are successively stacked in layers in an ascending order. The upper electrodes are formed independently for the individual capacitors formed in the directions of the columns. The capacitor insulating film is formed commonly to each of the capacitors. The side surfaces of each of the upper electrodes and the side surfaces of the capacitor insulating film are formed in continued relation with no stepped portion therebetween.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show a semiconductor device according to an embodiment of the present invention, of which FIG. 1A is a plan view thereof and FIG. 1B is a cross-sectional view taken along the line Ib-Ib of FIG. 1A;

FIGS. 2A and 2B show another example of the semiconductor device according to the embodiment of the present invention, of which FIG. 2A is a plan view thereof and FIG. 2B is a cross-sectional view taken along the line IIb-IIb of FIG. 2A;

FIGS. 3A to 3D are cross-sectional views illustrating a method for fabricating the semiconductor device according to the embodiment of the present invention in the order in which the process steps thereof are performed; and

FIGS. 4A to 4C are cross-sectional views illustrating the fabrication method for the semiconductor device according to the embodiment of the present invention in the order in which the process steps thereof are performed.

Claims

1. A semiconductor device comprising: an interlayer insulating film formed on a substrate; anda plurality of capacitors formed in directions of columns on the interlayer insulating film, whereineach of the capacitors has a lower electrode, a capacitor insulating film, and an upper electrode which are stacked in layers in an ascending order,the upper electrodes are independently formed for the individual capacitors formed in the directions of the columns,the capacitor insulating film is formed continuously over the respective lower electrodes of the capacitors, andside surfaces of each of the upper electrodes and side surfaces of the capacitor insulating film are formed in continued relation with no stepped portion therebetween.

2. The semiconductor device of claim 1, wherein a thickness of a portion of the capacitor insulating film which is formed between the individual capacitors is smaller than a thickness of a portion of the capacitor insulating film which is formed on each of the lower electrodes.

3. The semiconductor device of claim 1, wherein those of the plurality of capacitors formed in the directions of the columns which are formed on end portions of the columns are dummy capacitors each of which does not perform charge accumulation.

4. The semiconductor device of claim 1, wherein those of the plurality of capacitors formed in the directions of the columns which are formed on end portions of the columns have the upper electrodes which are larger in planar size than the upper electrodes of the other capacitors and the side surfaces of the upper electrodes of the capacitors formed on the end portions and the side surfaces of the capacitor insulating film thereof are located outwardly of the side surfaces of the lower electrodes thereof on a side opposite to a side on which the capacitors formed on the end portions are adjacent to the other capacitors.

5. The semiconductor device of claim 1, further comprising: a plurality of transistors each formed on the substrate and having diffusion layers; anda plurality of conductive plugs extending through the interlayer insulating film to electrically connect the individual diffusion layers of the transistors to the corresponding ones of the plurality of capacitors, whereineach of the lower electrodes has a multilayer structure including an oxygen barrier film and an electrode film.

6. The semiconductor device of claim 1, further comprising: a plurality of capacitors formed in directions of rows intersecting the directions of the columns, whereinthe respective upper electrodes of the plurality of capacitors formed in the directions of the rows are electrically connected to form cell plate lines.

7. The semiconductor device of claim 6, wherein the capacitor insulating film of each of the plurality of capacitors formed in the directions of the rows is integrally formed even between the capacitors formed in the directions of the rows.

8. A method for fabricating a semiconductor device, the method comprising the steps of: (a) forming a) plurality of lower electrodes in mutually spaced apart relation in a memory cell region of a substrate;(b) forming an insulating film for filling portions interposed between the individual lower electrodes;(c) forming a capacitor-insulating-film forming film over the individual lower electrodes and the insulating film;(d) forming an upper-electrode forming film on the capacitor-insulating-film forming film;(e) forming a plurality of upper electrodes by patterning the upper-electrode forming film; and(f) forming a capacitor insulating film by removing the capacitor-insulating-film forming film except for the memory cell region, whereinthe step (f) includes leaving the capacitor-insulating-film forming film in portions interposed between the individual upper electrodes and forming side surfaces of the upper electrodes and side surfaces of the capacitor insulating film in continued relation.

9. The method of claim 8, wherein dry etching is used to form the upper electrodes in the step (e) and form the capacitor insulating film in the step (f).

10. The method of claim 9, wherein a reactive ion etching apparatus is used to form the upper electrodes in the step (e) and form the capacitor insulating film in the step (f) and,when the capacitor insulating film is formed, an RF output of the reactive ion etching apparatus is set lower than when the upper electrodes are formed.

11. The method of claim 9, wherein, when the capacitor insulating film is formed, a pressure inside an etching chamber is set higher than when the upper electrodes are formed.

12. The method of claim 9, wherein, when the capacitor insulating film is formed, a gas containing carbon is used as an etching gas.

13. The method of claim 9, wherein the step (f) uses the same mask as used in the step (e).