JPS6298659A - Semiconductor device - Google Patents

Abstract

PURPOSE:To reduce an area occupied by a capacitance on a chip by forming an Al film onto a soft polyimide resin film as a foundation. CONSTITUTION:In a semiconductor base body 1, an active element 8, a passive element, etc. such as a transistor are formed to the surface, and the surface has oxide film SiO2 9, and has an Al electrode, first layer Al wirings 10, etc. connected in low resistance to diffusion layers for the elements. An organic insulating film 2 is shaped on the first layer Al wirings as an interlayer film, and consists of a high heat-resistant polyimide group high molecular resin-for example, a prepolymer liquid composed of a polyimide group resin acquired by reacting aromatic diamine and an aromatic tetracarboxylic acid anhydride is spinner-coated onto the surface of a substrate to which wirings are shaped, solvent components are evaporated,and the prepolymer liquid is polymerized and cured through heat treatment at 200-300 deg.C. An Al film 3 is formed onto the organic insulating film as the interlayer film at the same time as a second layer Al wiring. A thin dielectric film 4 is shaped onto the surface of the Al film 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a capacitor formation technique in a semiconductor device, particularly a semiconductor device having multilayer wiring.

[Background technology]

Capacitive elements built into semiconductor integrated circuit devices such as ICs and LSIs are broadly classified into (1) p
(2) MO3 capacity in which a metal film such as aluminum is layered on the surface of a semiconductor substrate via a silicon oxide film (Sing). As a modification of the MO8 capacitor, for example, according to the October 25, 11982 issue of Nikkei Electronics J published by Nikkei McGraw-Hill, a capacitor using a silicon nitride film (5isN+) instead of an oxide film is introduced.

In this case, St, N, have a high dielectric constant, so a fairly highly efficient capacitance can be obtained, but since a capacitance is formed between the Al film used for the first layer wiring and the diffusion layer, (
1) The chip area becomes large, (2) parasitic junction capacitance occurs between the diffusion layer and the substrate, and (3) the lateral series resistance of the diffusion layer that becomes one of the electrodes becomes large. It has been found by the inventor of this application that there is a problem.

In addition, there is MIM in which the AA film of the second layer wiring is overlaid on the A2 film of the first layer wiring in a multilayer wiring via a thin dielectric film.
A (metal/insulator/metal) type capacitor has been proposed by the inventors of the present application. However, in this case, the first layer of AA film is formed on a hard base substrate or underlying SiO film, but there is a layer of 0 called Hiruronox on the AJIlt film surface.
, protrusions of 5 to 1.5 μm are likely to occur. For this reason, it has been found that when the dielectric film formed on the first layer A layer is thin, this hiruronox penetrates the dielectric film and short-circuits the upper and lower electrical connections.

[Purpose of the invention]

The present invention has been made to overcome the above-mentioned problems.

One object of the present invention is to provide an MIM capacitor that is independent of the underlying structure and does not take up too much space on a chip.

Another object of the present invention is to reduce the influence of hillock
The objective is to provide IM capacity.

The above and other objects and novel features of the present invention include:
It will become clear from the description of the invention and the accompanying drawings.

[Summary of the Invention] A brief overview of typical inventions disclosed in this application is as follows.

That is, in a device in which an organic film such as a polyimide resin is formed as a wiring base film or a wiring interlayer film on a semiconductor substrate, a first A2 film forming a first electrode formed on this organic film, and a first A2 film formed on the organic film as a first electrode. A! II! A capacitor is formed by a thin dielectric film formed on the film and a second A2 film formed on the dielectric film, which becomes a second electric field, and is formed on a soft polyimide resin film as the base. By forming the A2 film on the interlayer film, hillocks can be prevented even when a thin dielectric film is formed, and by using the A2 film on the interlayer film, the area occupied by the capacitance on the chip can be avoided. , the object of the invention can be achieved.

[Embodiment 1] FIGS. 1 to 4 show an embodiment of the present invention, and are cross-sectional views of a process for forming an MIM capacitor on a semiconductor substrate.

(1) An organic insulating film is formed on a silicon semiconductor substrate, and the A film 3, which is one electrode of the capacitor, is formed on this film. (Fig. 1) Referring to the fifth factor, the semiconductor substrate 1 has active elements (8) such as transistors, passive elements, etc. formed on its surface, and has an oxide film (Sin, etc.) formed on its surface. (9), and includes an A1 electrode connected with low resistance to the diffusion layer of the above element, a first layer A stone wiring 00), and the like.

The organic insulating film 2 is formed as an interlayer film on the second layer A2 wiring, and is made of day heat-resistant polyimide polymer resin, for example, aromatic diamine and aromatic tetracarboxylic dianhydride. After applying a prepolymer residue of polyimide resin obtained by reacting with
It is polymerized and hardened by heat treatment at 0°C.

An An film 3 is a second /u A film on an organic insulating film which is an interlayer film.
, 6 are formed at the same time, and after A-e vapor deposition (sputtering), patterning is performed using a photoresist mask into the shape and size of the required capacitance.

(A thin dielectric film 4 is formed on the surface of the 21A-g film 3.

This dielectric material is, for example, plasma nitride P-3i
N (permittivity!=6.7), Si nitride, N.

(permittivity = 7.0) or 1 liter of plasma silicon
The thickness of the ff film P-8iO, (permittivity 4, O-4, 3)'Y used is 100 to 1 oooi. (Figure 2)
(3) A second layer organic film 5 of polyimide resin or the like is formed on the entire surface, and a through hole 6 having the area shape of the required capacity is formed by photoetching.

For this through-hole etch, 40 to 80% of hydrazine is used.
Use an aqueous solution etc. (FIG. 3) (4) Form the A2 film 7 which is the other electrode of the capacitor.

This AAllU7 is formed on the organic film 5 of the second layer at the same time as the formation of the A2 pattern mav of the third layer.

FIG. 5 is a partial sectional view showing an example of a semiconductor integrated circuit device obtained by the above process. In the figure, 8 is an active element diffusion layer, 9 is a substrate surface Sin,
11 is the second layer A2 wiring, 12 is the 38th ik13 wiring.

〔Effect of the invention〕

According to the present invention described in the embodiments above, the following effects can be obtained.

(1) In a multilayer wiring structure, the first layer wiring usually has a high wiring density for taking out electrodes from each element, so there is little room for adding capacity here. On the other hand, the wiring density in the second and higher layers is not as high as that in the first layer, and the capacitance is created in the second and third layers.

It has little effect on the underlying element structure, and high capacitance can be obtained over a wide area.

(2) Since the 111th electrode of the capacitor is provided on a flexible organic insulating film, stress is not applied even when A2 is used, so hirronox is less likely to occur.

Therefore, a thin dielectric film can be formed thereon, and a high capacity can be achieved.

(3) From (1) (2+) above, it is possible to form a high capacity tht without increasing the chip area. For example, it is possible to incorporate a video band filter.

Although the invention made by the present invention has been specifically explained above based on the examples, the present invention is not limited to the above-mentioned examples, and various changes can be made without departing from the gist thereof.

For example, by mixing boron into A-g used for the first m-electrode of the capacitor, it is possible to form a more reliable capacitor with less generation of hiruronox.

More il, @21! As the pole, A2 alloy, titanium T
It goes without saying that it can also be formed using i, tantalum Ta, tungsten W, or polysilicon (So [Field of Application] The present invention is applicable to all semiconductor devices having a multilayer wiring structure using an organic insulating film.

[Brief explanation of drawings]

1 to 4 are process cross-sectional views of a capacitive element forming process showing one embodiment of the present invention. FIG. 5 is a partial sectional view of a semiconductor integrated circuit device with a built-in capacitive element, showing an application example of the present invention. ■...Semiconductor substrate, 2...Organic insulating film, 3...First
A, 8 films ('dL pole), 4... dielectric film, 5...
second organic insulating film, 6... through hole, 7... second A shadow film (electrode);

Claims (1)

[Claims] 1. In a semiconductor device having a wiring base film or an interlayer film on a semiconductor substrate, a first wiring electrode film formed on the film and a thin film formed on the surface of the first wiring electrode film A semiconductor device characterized in that a capacitor is formed by a dielectric film and a second wiring electrode film formed on the dielectric film. 2. The semiconductor device according to claim 1, wherein the base film or interlayer film is made of polyimide resin.