JPH05267290A - Semiconductor integrated circuit and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a semiconductor integrated circuit having a metallic wiring of a shape which can improve the step coverage of a coating film, by causing the metallic wiring to have a structure in which the metallic wiring has, in the vertical section thereof, an obtuse angle formed between the upper surface and the side thereof and has an acute angle formed between the undersurface and the side thereof CONSTITUTION:In a semiconductor integrated circuit having a metallic wiring 5 connecting elements and circuits, the metallic wiring 5 is provided with a structure in which the metallic wiring has, in the vertical section thereof, an angle greater than 90 degrees formed between the upper surface and the side thereof and has an angle not greater than 90 degrees formed between the undersurface and the side thereof. When a layer insulation film 2 is formed on a semiconductor substrate 1 and a metallic layer 3 becoming a wiring is formed thereon to manufacture a semiconductor integrated circuit, a photoresist film 4 is formed on the upper surface of the metallic layer 3 and a desired metallic wiring is patterned. Then, with the photoresist film 4 as a mask the metallic layer 3 is etched by an isotropic etching process. Next, an etching is performed by an anisotropic etching process to form the metallic wiring 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a semiconductor integrated circuit and a method for manufacturing the same, and more particularly to a shape of metal wiring and a method for forming the same.

[0002]

2. Description of the Related Art Since aluminum wiring of a conventional semiconductor integrated circuit is formed by using only anisotropic etching by dry etching, as shown in FIG. Had a right angle or an acute angle.

When a passivation film 6 such as a PSG film is grown on the aluminum wiring 5 having such a shape,
Since the passivation film 6 grows thickly in a sharply-grounded portion of the base, that is, at an angle portion where the upper surface and the side surface of the aluminum wiring 5 are in contact with each other, the passivation film 6 has a shape with poor step coverage.

[0004]

In the shape of the aluminum wiring in the conventional semiconductor integrated circuit, the angle portion where the upper surface is in contact with the side surface is vertical or acute, and the passivation film concentrates and grows at this angle portion. The step coverage of the passivation film was poor, and thick and thin portions of the passivation film were formed. The thick part of the passivation film has a drawback that the passivation film of the adjacent aluminum wiring is in contact with the thick part, and the thin part of the passivation film has a drawback that it has poor moisture resistance and is weak against stress.

An object of the present invention is to provide a semiconductor integrated circuit having a metal wiring having a shape capable of improving the step coverage of a coating film by eliminating the above-mentioned drawbacks, and a method of manufacturing the same.

[0006]

The semiconductor integrated circuit of the present invention is a semiconductor integrated circuit having a metal wiring for connecting elements and circuits, wherein the metal wiring has an angle between a top surface and a side surface in a vertical cross section thereof. Is greater than 90 degrees, and the angle between the bottom surface and the side surface is 90 degrees or less.

The method for manufacturing a semiconductor integrated circuit according to the present invention is the method for manufacturing a semiconductor integrated circuit, comprising the step of forming an interlayer insulating film on a semiconductor substrate and forming a metal layer to be a wiring thereon. A step of forming a photoresist film on the upper surface of the layer and patterning a desired metal wiring, then a first etching step of etching the metal layer by an isotropic etching method using the photoresist film as a mask, and then an anisotropic method A second etching step of forming the metal wiring by etching by a positive etching method.

[0008]

The metal wiring, for example, the aluminum wiring has a shape in which the angle between the upper surface and the side surface of the vertical section is larger than 90 degrees,
Since the angle between the lower surface and the side surface is 90 degrees or less, the passivation film can be spread sufficiently over the lower surface without being concentrated on the upper surface of the aluminum wiring, and it is possible to prevent the deterioration of the step coverage. Becomes

Further, as a method of manufacturing the metal wiring having such a shape, when the metal wiring is formed from the metal layer by etching, first, the upper surface portion of the metal wiring is formed by the isotropic etching method. It is possible to manufacture by making all the angled parts of the upper surface obtuse and then making the angled parts of the lower surface 90 degrees or less by the anisotropic etching method.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a main part of an embodiment of a semiconductor integrated circuit according to the present invention.

This embodiment is a semiconductor integrated circuit having an aluminum wiring 5 as a metal wiring formed on a semiconductor substrate 1 with a silicon oxide film 2 interposed therebetween. The vertical cross section has a structure in which the angles formed by the top surface and the side surfaces are all greater than 90 degrees, and the angles formed by the bottom surface and the side surfaces are all 90 degrees or less.

In the present embodiment, due to the structure of the aluminum wiring 5, the passivation film 6 does not concentrate on the upper surface of the aluminum wiring 5 and often spreads to the lower surface portion, and each portion is formed with a substantially uniform thickness. Step coverage does not deteriorate.

Next, the manufacturing method of this embodiment will be described with reference to FIG.
This will be described with reference to (a), (b) and (c).

First, as shown in FIG. 2A, a silicon oxide film 2 is formed on the upper surface of a semiconductor substrate 1, an aluminum layer 3 is formed on the upper surface thereof, and a photoresist film 4 is further formed on the upper surface thereof, followed by photolithography. The photoresist film 4 is patterned for aluminum wiring by using a technique.

Next, as shown in FIG. 2B, the aluminum layer 3 is first dry-etched under isotropic etching conditions to form a curved portion.

Next, as shown in FIG. 2C, as the second dry etching, the conventional anisotropic etching is performed to form the aluminum wiring 5.

With the aluminum wiring 5 thus formed, the passivation film 6 can uniformly coat the aluminum wiring 5 as shown in FIG.

In the above description, the metal wiring is an aluminum wiring and the coating is a passivation film, but the same applies to other materials.

[0020]

As described above, according to the present invention, for example, the angle between the upper surface and the side surface of the aluminum wiring is larger than 90 degrees, and the angle between the bottom surface and the side surface is 90 degrees or less. This has the effect of improving the step coverage of, for example, a passivation film covering the wiring.

Therefore, according to the present invention, the contact of the passivation film between the adjacent aluminum wirings is prevented, and the extremely thin portion of the passivation film is eliminated, so that the moisture resistance of the product is improved and further the passivation film on the aluminum wiring is improved. Since the film is uniformly coated, the stress from the passivation film to the aluminum wiring is not concentrated on a part, stress migration is less likely to occur, and the effect is great.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of an embodiment of a semiconductor integrated circuit of the present invention.

FIG. 2 is a process cross-sectional view showing the main parts of the manufacturing method.

FIG. 3 is a cross-sectional view showing a main part of a conventional semiconductor integrated circuit.

[Explanation of symbols]

 1 Semiconductor Substrate 2 Silicon Oxide Film 3 Aluminum Layer 4 Photoresist Film 5 Aluminum Wiring 6 Passivation Film

Claims (2)

[Claims] 1. A semiconductor integrated circuit having metal wiring for connecting an element and a circuit, wherein the metal wiring has an angle between a top surface and a side surface of more than 90 degrees in a vertical cross section, and a bottom surface and a side surface. 1. A semiconductor integrated circuit having a structure in which an angle formed by is 90 degrees or less. 2. A method of manufacturing a semiconductor integrated circuit, which includes a step of forming an interlayer insulating film on a semiconductor substrate and forming a metal layer to be a wiring thereon, wherein a photoresist film is formed on the upper surface of the metal layer to form a desired metal. A step of patterning the wiring, then a first etching step of etching the metal layer by an isotropic etching method using the photoresist film as a mask, and then etching by an anisotropic etching method to form the metal wiring. And a second etching step for forming the semiconductor integrated circuit.