JPH09172076A - Method for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To readily and accurately remove a sub-product produced in dry- etching by a method wherein, after an insulation layer is dry-etched via a resist layer to form a via hole, the via hole is washed with a detergent, and thereafter after it is ultrasonic-washed through a solvent, it is washed again with a detergent. SOLUTION: After dry-etching, a reaction by-product 15 considered as an aluminum fluoride or oxide is generated on inner and bottom faces of a via hole 13a. Then, washing is performed with a nitride acid solution. In order to remove the remaining reaction by-product 15, by use of pure water as a solvent, ultrasonic-washing is performed at output 100W, frequency 45000Hz for about 10min. Thereby, the reaction sub-product 15 is oscillated and is in a state that the reaction by-product 15 is easy to separate from the inner and bottom faces of the via hole 13a. When washing is performed with a nitric acid solution for 4min., the reaction by-product 15 can almost completely be removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a semiconductor device for manufacturing a semiconductor device in which wiring layers formed on both sides of an insulating layer are connected to each other through via holes. The present invention relates to a method of manufacturing a device.

[0002]

2. Description of the Related Art In recent years, in a semiconductor device, as the degree of integration thereof has been improved, it has become necessary to stack a number of fine wiring layers through an insulating layer. Wiring layers formed on both sides of the layer are connected to each other through fine connection holes called via holes.

FIG. 3 shows a conventional manufacturing method of this type of semiconductor device. In this manufacturing method, as shown in FIG. 3A, a first wiring layer 2 containing aluminum is formed on a semiconductor substrate 1. And the insulating layer 3 is formed on the first wiring layer 2. Then, the resist layer 4 is formed on the insulating layer 3. Minute holes 4a are formed in the resist layer 4 at positions corresponding to the via holes 3a in (b) by a normal photolithography process.

Next, as shown in (b), a via hole 3a is formed in the insulating layer 3 by performing dry etching using a fluoride gas such as CF4 and CHF3 through the hole 4a of the resist layer 4. It is formed. After this dry etching, reaction by-products 5, which are considered to be fluorides or oxides of aluminum, are formed on the inner surface and the bottom surface of the via hole 3a.

Then, next, as shown in (c), in order to remove the resist layer 4 and the reaction by-product 5, cleaning with a nitric acid solution is performed. Thereafter, as shown in (d), the second wiring layer 6 is deposited and formed by sputtering or chemical vapor deposition (hereinafter abbreviated as CVD method).

[0006]

However, such a conventional method for manufacturing a semiconductor device has a problem that the reaction by-product 5 cannot be completely removed by cleaning with a nitric acid solution.

That is, for example, as shown in FIG. 3C, the via hole 3 is formed by the remaining reaction by-product 5a.
When the entrance of a is blocked, as shown in (d), when the second wiring layer 6 is deposited and formed, the cavity 3 is formed in the via hole 3a.
b occurs, connection failure occurs between the second wiring layer 6 and the first wiring layer 2, and the yield of semiconductor devices decreases.

Further, for example, when the reaction by-product 5b remains on the inner surface of the via hole 3a as shown in FIG. 4C, the second wiring is formed by the subsequent heat treatment step as shown in FIG. 4D. The layer 6 is corroded, the disconnection portion 6a is generated, and the yield of the semiconductor device is reduced. Note that each step of FIG.
The detailed description is omitted because it is almost the same as each step.

The present invention has been made in order to solve such a conventional problem, and provides a method of manufacturing a semiconductor device capable of easily and surely removing a reaction by-product generated when a via hole is formed by dry etching. The purpose is to provide.

[0010]

According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device, which comprises a step of forming a first wiring layer containing aluminum on a semiconductor substrate, and an insulating layer on the first wiring layer. A step of forming, a step of forming a resist layer having a predetermined pattern on the insulating layer, a step of dry etching the insulating layer through the resist layer to form a via hole in the insulating layer, and a cleaning solution for the via hole. A step of cleaning, a step of ultrasonically cleaning the via hole with a solvent, a step of cleaning the via hole with a cleaning liquid, and a step of connecting to the first wiring layer at a position of the via hole on the insulating layer. And a step of forming two wiring layers.

A method of manufacturing a semiconductor device according to a second aspect is the method of manufacturing a semiconductor device according to the first aspect, characterized in that the cleaning liquid is an aqueous solution having a nitric acid component of 98% by weight or more.

According to a third aspect of the present invention, there is provided a method of manufacturing a semiconductor device according to the first or second aspect, wherein the ultrasonic cleaning solvent is pure water or lower alcohol. A method of manufacturing a semiconductor device according to a fourth aspect is the method of manufacturing a semiconductor device according to any one of the first to third aspects, wherein an isotropic layer is formed on the resist layer side of the insulating layer in a step before the dry etching. It is characterized by performing etching.

(Operation) In the method of manufacturing a semiconductor device according to claim 1, when the insulating layer is dry-etched through the resist layer to form a via hole in the insulating layer, a reaction by-product is generated in the via-hole, and this reaction by-product is generated. However, it cannot be sufficiently removed even by the subsequent cleaning for removing the resist layer and remains.

When the reaction by-product that remains in this way is ultrasonically cleaned through a solvent, the reaction by-product is easily separated from the inner surface and the bottom surface of the via hole due to vibration, and the next cleaning solution is used for cleaning. Is reliably removed by. In the method for manufacturing a semiconductor device according to the second aspect, the cleaning liquid is an aqueous solution containing 98% by weight or more of nitric acid component.

In the semiconductor device manufacturing method of the third aspect, pure water or lower alcohol is used as the solvent for ultrasonic cleaning. In the method of manufacturing a semiconductor device according to claim 4, in a pre-process of dry etching, isotropic etching is performed on the resist layer side of the insulating layer, and a surface of the insulating layer whose diameter is expanded toward the resist layer is formed. A catch is formed.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a process diagram showing a first embodiment of a method for manufacturing a semiconductor device of the present invention.

In the first embodiment, as shown in (a), a first wiring layer 12 containing aluminum is formed on a semiconductor substrate 11 made of a silicon substrate. Then, a silicon oxide-based or silicon nitride-based insulating layer 13 is formed on the first wiring layer 12. Then, the resist layer 14 is formed on the insulating layer 13.

In this resist layer 14, a minute hole portion 14a is formed at a position corresponding to the via hole 13a of (b) by an ordinary photolithography process. Next,
As shown in (b), a via hole 13a is formed in the insulating layer 13 by performing dry etching using a fluoride-based gas such as CF4 or CHF3 through the hole 14a of the resist layer 14.

After this dry etching,
On the inner surface and the bottom surface of the via hole 13a, a reaction by-product 1 that is considered to be a fluoride or oxide of aluminum 1
5 results. Then, next, the resist layer 14 of (b)
And, in order to remove the reaction by-product 15, washing with a nitric acid solution is performed for about 4 minutes.

In this washing, the reaction by-product 15
In this embodiment, in order to remove the residual reaction by-product 15, first,
Ultrasonic cleaning is performed. This ultrasonic cleaning is performed with pure water as a solvent at an output of 100 W and a frequency of 45000 Hz for about 10 minutes.

By this ultrasonic cleaning, the reaction by-product 15
Is vibrated, and the reaction by-product 15 is easily separated from the inner surface and the bottom surface of the via hole 13a. Then, cleaning with a nitric acid solution is performed for about 4 minutes, and the reaction by-product 15 is almost completely removed as shown in (c).

Thereafter, as shown in (d), the second wiring layer 16 is deposited and formed by the sputtering method. And
At the time of depositing and forming the second wiring layer 16, the via hole 1
Since the reaction by-product 15 does not exist in 3a, the second wiring layer 16 is reliably connected to the first wiring layer 12 at the position of the via hole 13a.

In this embodiment, an aqueous solution containing 98% by weight of nitric acid component is used as the above-mentioned nitric acid solution. In the semiconductor device manufacturing method described above, the reaction by-product 15 generated in the via hole 13a is ultrasonically cleaned and vibrated through pure water, and the reaction by-product 15 is vibrated.
Since the via hole 13a is washed with a nitric acid solution after being easily peeled from the inner surface and the bottom surface, the reaction by-product 15 generated when the via hole 13a is formed by dry etching can be easily and surely removed. it can.

Since the reaction by-product 15 does not exist in the via hole 13a, the via hole 13a is blocked by the reaction by-product 15 or the second reaction layer 15 is corroded by the remaining reaction by-product 15. It is possible to reliably connect the first wiring layer 12 and the second wiring layer 16 at the position of the via hole 13a, and the yield of the semiconductor device can be improved.

Further, in the above-described method for manufacturing a semiconductor device, since the cleaning solution is an aqueous solution having a nitric acid component of 98% by weight or more, the reaction by-product 15 can be effectively removed. Since this aqueous solution is generally commercially available, a commercially available product can be used as it is.

Further, in the above-described method for manufacturing a semiconductor device, since pure water is used as the solvent for ultrasonic cleaning, the reaction by-product 15 can be effectively vibrated so that it can be easily peeled off. 2A to 2D are process diagrams showing a second embodiment of the method for manufacturing a semiconductor device of the present invention. In the second embodiment, after the via hole is isotropically dry-etched,
It is different from the first embodiment in that it is formed by performing anisotropic dry etching.

That is, in the second embodiment, as shown in FIG.
(B), first, the resist layer 14 side of the insulating layer 13 is subjected to isotropic dry etching to form the insulating layer 1
A chamfered portion 13b whose diameter is increased toward the resist layer 14 is formed on the side of the resist layer 14 of No. 3. The etching amount of this isotropic dry etching is set in the via hole 13A as shown in (e) in consideration of the aspect ratio of the via hole 13A to be formed, the film thickness of the second wiring layer 16, and the like. It is selected so that the second wiring layer 16 can be well covered.

Then, as shown in (c), anisotropic dry etching is performed on the remaining film of the insulating layer 13 to form a via hole 13A. Then, the reaction by-product 15 generated at this time is surely removed by the same method as in the first embodiment. Since the second embodiment is almost the same as the first embodiment except that isotropic dry etching is performed, detailed description of the same parts will be omitted.

In the above-described method for manufacturing a semiconductor device, the chamfered portion 13b whose diameter is expanded toward the resist layer 14 of the insulating layer 13 by the isotropic dry etching is used.
The second wiring layer 1 is formed as shown in FIG.
6 is formed along the chamfered portion 13b, and as a result, the first wiring layer 12 and the second wiring layer 16 can be reliably connected at the position of the via hole 13A.

In the above-described embodiment, an example in which a nitric acid solution is used as the cleaning liquid has been described, but the present invention is not limited to this embodiment, and for example, an organic system such as trichloroethylene, xylene, acetone, etc. You may use the cleaning liquid of this. Further, in the above-described embodiment, an example in which pure water is used as a solvent for ultrasonic cleaning has been described, but the present invention is not limited to such an embodiment, and for example, lower alcohols, ethers, ketones, etc. May be used.

Furthermore, in the above-described embodiment, an example in which the second wiring layer 16 is formed by the sputtering method has been described, but the present invention is not limited to this embodiment, and is formed by, for example, the CVD method. You may. Also,
In the embodiment described above, the first and second wiring layers 1
Although the example in which 2 and 16 are single layers has been described, the present invention is not limited to such an embodiment, and each wiring layer may be a laminated wiring.

For example, the first wiring layer 12 may be a laminated wiring formed of a combination of an aluminum-containing layer and a titanium alloy, and the second wiring layer 16 may be a tungsten layer formed by a CVD method. Alternatively, a laminated wiring formed of a combination of a titanium alloy and an aluminum-containing layer can be used. Furthermore, in the embodiment described above, the first wiring layer 12 and the second wiring layer 1
Although the example in which 6 and 6 are connected via via holes 13a and 13A has been described, the present invention is not limited to this embodiment, and is similarly applied to the connection via via holes of three or more wiring layers. be able to.

In the second embodiment described above, an example in which the chamfered portion 13b is formed by dry etching has been described. However, the present invention is not limited to this embodiment, and chamfering by wet etching is performed. You may form a part.

[0034]

As described above, in the method of manufacturing a semiconductor device according to the first aspect, the reaction by-product generated in the via hole is ultrasonically cleaned and vibrated through a solvent, and the reaction by-product is formed on the inner surface of the via hole. Since the via hole is cleaned with the cleaning liquid after the state where the via hole is easily separated from the bottom surface, the reaction by-product generated when the via hole is formed by dry etching can be easily and surely removed.

Since there is no reaction by-product in the via hole, the first wiring layer and the second wiring layer can be reliably connected at the position of the via hole, and the yield of the semiconductor device can be improved. it can. Further, according to the manufacturing method of the present invention, it becomes possible to easily remove the reaction by-product without using special chemicals or equipment and only with general chemicals and equipment for manufacturing semiconductor devices. .

In the method of manufacturing a semiconductor device according to the second aspect, since the cleaning solution is an aqueous solution containing 98% by weight or more of nitric acid component, the reaction by-product can be effectively removed. Moreover, since this aqueous solution is generally commercially available, a commercially available product can be used as it is. In the method for manufacturing a semiconductor device according to the third aspect, since pure water or lower alcohol is used as the solvent for ultrasonic cleaning, it is possible to effectively vibrate the reaction by-product so that it can be easily peeled off.

Since lower alcohols are generally commercially available, they can be easily obtained. In the method for manufacturing a semiconductor device according to claim 4, in the pre-process of dry etching, a chamfered portion whose diameter increases toward the resist layer is formed on the resist layer side of the insulating layer. Therefore, the first wiring layer and the second wiring layer can be reliably connected at the position of the via hole.

[Brief description of the drawings]

FIG. 1 is a process drawing showing a first embodiment of a method for manufacturing a semiconductor device of the present invention.

FIG. 2 is a process drawing showing a second embodiment of the method for manufacturing a semiconductor device of the present invention.

FIG. 3 is a process chart showing an example of a conventional method for manufacturing a semiconductor device.

FIG. 4 is a process chart showing another example of the conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

 11 Semiconductor Substrate 12 First Wiring Layer 13 Insulating Layer 13a, 13A Via Hole 14 Resist Layer 15 Reaction By-Product 16 Second Wiring Layer

Claims (4)

[Claims] 1. A step of forming a first wiring layer containing aluminum on a semiconductor substrate, a step of forming an insulating layer on the first wiring layer, and a resist layer having a predetermined pattern on the insulating layer. A step of forming a via hole in the insulating layer by dry etching the insulating layer through the resist layer, a step of cleaning the via hole with a cleaning liquid, and an ultrasonic cleaning of the via hole with a solvent. And a step of cleaning the via hole with a cleaning solution, the first hole at a position of the via hole on the insulating layer.
And a step of forming a second wiring layer connected to the wiring layer, the method for manufacturing a semiconductor device. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the cleaning liquid is an aqueous solution containing a nitric acid component of 98% by weight or more. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the solvent for the ultrasonic cleaning is pure water or lower alcohol. 4. The method for manufacturing a semiconductor device according to claim 1, wherein isotropic etching is performed on a resist layer side of the insulating layer in a step before the dry etching. And a method for manufacturing a semiconductor device.