JPH05129522A - Semiconductor device - Google Patents

Abstract

PURPOSE:To reduce the defect of a capacitor in a semiconductor device wherein at least one electrode for the capacitor is constituted of an aluminum electrode. CONSTITUTION:A field insulating layer 12, an interlayer insulating layer 13, an insulating layer 14 for capacitor use, an electrode 15, for lower-side capacitor use, which uses a high-melting-point metal, an aluminum electrode 16 to be used as an electrode for upper-side capacitor use and a conductive protective layer 17 using a high-melting-point metal are formed respectively on the main face side of a silicon substrate 11. Since the protective layer 17 is formed between the insulating layer 14 for capacitor use and the aluminum electrode 16, it is possible to restrain a hillock from being formed during a heat treatment and to enhance the dielectric breakdown strength of a capacitor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to the structure of its capacitor.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view showing a conventional example and shows a structure of a capacitor in a silicon integrated circuit.

A field insulating layer 52, an interlayer insulating layer 53 made of silicon oxide, a capacitor insulating layer 54 made of silicon nitride, a capacitor electrode 55 made of molybdenum, and aluminum are provided on the main surface side of the silicon substrate 51. Is used to form a capacitor electrode 56 (aluminum electrode).

[0004]

In the above-mentioned conventional example, when the film thickness of the capacitor insulating layer 54 becomes thin (especially 10 nm).
Below), it was confirmed that the number of defective capacitors increased. The reason for this is considered to be that hillocks are formed on the surface of the aluminum electrode 56 during the heat treatment process, and local concentration of an electric field occurs due to the hillocks, resulting in a decrease in the dielectric strength voltage of the capacitor.

An object of the present invention is to reduce defective capacitors in a semiconductor device in which at least one electrode of the capacitor is formed of an aluminum electrode.

[0006]

A semiconductor device according to the present invention is a semiconductor device in which at least one electrode of a capacitor formed on the main surface side of a semiconductor substrate is formed of an aluminum electrode. And a conductive protective layer is formed between the aluminum electrode and the aluminum electrode. The protective layer is preferably formed using a refractory metal or a refractory metal compound.

[0007]

FIG. 1 is a sectional view showing a first embodiment of the present invention, showing the structure of a capacitor in a silicon integrated circuit. On the main surface side of the silicon substrate 11, a field insulating layer 12, an interlayer insulating layer 13 using silicon oxide (film thickness of about 500 nm), a capacitor insulating layer 14 using silicon nitride (film thickness of about 5 to 10 nm), Lower capacitor electrode 1 using refractory metal such as molybdenum
5 (thickness: about 200 nm), an aluminum electrode 16 (thickness: about 800 to 1000 nm) to be an upper capacitor electrode, and a conductive protective layer 17 (thickness: about 50 to 100 nm) using a refractory metal such as molybdenum. , Respectively. The capacitor insulating layer 14, the lower capacitor electrode 15, the aluminum electrode 16 and the protective layer 17 form a capacitor. In addition to the refractory metal, the capacitor electrode 15 and the protective layer 17 have a refractory metal compound (a compound of a refractory metal and silicon (silicide), a refractory metal nitride (for example, TiN), or the like).
May be used. In this way, the capacitor insulating layer 14
Since the protective layer 17 is formed between the aluminum electrode 16 and the aluminum electrode 16, the formation of hillocks is suppressed during the heat treatment, and the withstand voltage of the capacitor is improved.

FIG. 2 is a sectional view showing a second embodiment of the present invention, which shows the structure of a capacitor in a silicon integrated circuit. Constituent elements which are substantially the same as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. In this embodiment, the lower capacitor electrode is formed of an aluminum electrode 21 (film thickness of about 800 to 1000 nm), and the upper capacitor electrode 22 (film thickness of about 200 nm) is formed of a high melting point metal such as molybdenum or a high melting point metal compound ( Compound of high melting point metal and silicon (silicide),
It is formed by using a refractory metal nitride (for example, TiN) or the like, and a conductive protective layer 23 (film thickness of about 50 to 100 nm) is formed between the capacitor insulating layer 14 and the aluminum electrode 21. is there. Also in this embodiment, the same effect as that of the first embodiment can be obtained.

FIG. 3 is a sectional view showing a third embodiment of the present invention, which shows the structure of a capacitor in a silicon integrated circuit. Constituent elements which are substantially the same as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. In this embodiment, the lower capacitor electrode and the upper capacitor electrode are replaced by aluminum electrodes 31 and 32.
(Both having a film thickness of about 800 to 1000 nm), and conductive protective layers 33 and 34 between the capacitor insulating layer 14 and the aluminum electrode 31 and between the capacitor insulating layer 14 and the aluminum electrode 32. (Both have a film thickness of about 50 to 100 nm). Also in this embodiment, the same effects as those of the first and second embodiments are obtained.

[0010]

According to the present invention, since the conductive protective layer is formed between the insulating layer for capacitors and the aluminum electrode,
The formation of hillocks is suppressed during the heat treatment, and the withstand voltage of the capacitor is improved. Therefore, it is possible to significantly reduce the number of defective capacitors.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

FIG. 3 is a sectional view showing a third embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a conventional example.

[Description of reference numerals] 11 ... Silicon substrate (semiconductor substrate) 14 ... Capacitor insulating layer 16, 21, 31, 32 ... Aluminum electrode 17, 23, 33, 34 ... Protective layer

Claims (2)

[Claims] 1. A semiconductor device in which at least one electrode of a capacitor formed on the main surface side of a semiconductor substrate is composed of an aluminum electrode, wherein a conductive layer is provided between a capacitor insulating layer of the capacitor and the aluminum electrode. A semiconductor device having a protective layer. 2. The semiconductor device according to claim 1, wherein the protective layer is formed using a refractory metal or a refractory metal compound.