JPH0546997B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a multilayer wiring board, and particularly relates to a method for manufacturing a multilayer wiring board, and particularly relates to a method for manufacturing a multilayer wiring board, and particularly relates to a method for manufacturing a multilayer wiring board, and particularly relates to a method for manufacturing a multilayer wiring board. The present invention relates to a method for improving contactability.

[Prior art and its problems] As semiconductor technology progresses, semiconductor devices continue to become more highly integrated.As a result, there is a growing demand for smaller wiring areas, and multilayer wiring patterns are becoming essential. I'm getting used to it.

As described above, as wiring patterns become more multilayered, the higher the layer, the more the surface level difference increases, making it difficult to obtain sufficient pattern accuracy. Therefore, various studies are being carried out to flatten the surface.

Among these, a method of using an organic insulating film such as polyimide as an interlayer insulating film instead of an inorganic insulating film such as a silicon oxide film formed by CVD is attracting attention.

This polyimide film is very easily formed on the substrate surface by a coating method such as spin coating, and since it has fluidity during coating, the surface after coating tends to be flat. In addition, since it can be formed without going through a high-temperature process, it can be used even in cases where the lower layer contains a low melting point metal such as aluminum, so it is becoming widely used.

Conventionally, when using this polyimide film as an interlayer insulating film, through holes were formed as follows.

First, as shown in FIG. 5a, a polyimide film 3 is applied to the substrate 1 on which the first wiring layer 2 is formed.
Furthermore, as shown in FIG. 5b, a photoresist 4 is applied to the surface.
is applied and selectively exposed through a photomask 5.

Then, as shown in FIG. 5c, it is immersed in an etching solution such as sodium silicate, the resist is developed, and the polyimide film is selectively removed to form a through hole h.

Then, as shown in FIG. 5d, after removing the resist pattern, a second wiring layer 6 is formed on this upper layer, and the first wiring layer 6 is connected to the second wiring layer via a through hole h. However, with this method of forming through holes using only wet etching, the polyimide inside the through holes cannot be completely removed, leaving a very thin organic film O, etc. There was a problem that it was not possible to make regular contact with other people. This problem occurs not only in polyimide films but also in other organic films.

On the other hand, when attempting to pattern a polyimide film by dry etching, the etching selectivity with the resist is small, resulting in a decrease in pattern accuracy, and it is difficult to remove the resist pattern after dry etching, making it practical. There are many problems with this.

Therefore, a method has been adopted in which after forming a through hole by wet etching, the organic film O and the like remaining on the surface of the through hole are removed by plasma cleaning using oxygen plasma.

However, since this method requires a vacuum device, it is difficult to apply to large-area substrates and also increases manufacturing time, which is a major obstacle to simplifying the process and reducing manufacturing costs.

Furthermore, when forming a fine pattern, a reduction in reliability due to damage caused by plasma during a plasma cleaning process also becomes a problem.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a multilayer wiring board that is easy to manufacture and has high reliability.

[Means for Solving the Problems] Accordingly, in the present invention, after forming an organic insulating film such as polyimide and drilling through holes using a wet etching method, the surface of the substrate is exposed to ultraviolet rays before forming a wiring layer. I'm trying to irradiate it.

[Function] By irradiating the substrate surface with ultraviolet rays, the organic film remaining in the through-holes can be removed and a clean surface can be exposed. Therefore, when a wiring layer is formed on top of this, good contact properties can be achieved. can be obtained.

That is, there are two mechanisms for the decomposition of residues such as C, H, O, and N by ultraviolet irradiation.
One is the activation and decomposition of residual molecules by ultraviolet rays,
The other is the decomposition of residues due to strong oxidation in the process of O ₃ production and decomposition.

First, when oxygen O ₂ in the air is irradiated with ultraviolet rays, O ₃ is generated.

hν O ₂ →O+O, O ₂ +O→O ₃ where hν is ultraviolet rays Also, when this O ₃ is exposed to ultraviolet rays, O ₃ →O ₂ +O and active oxygen is generated. This active oxygen O caused by repeated decomposition and production of O ₃ causes a strong oxidizing effect on the residual molecules. As a result, residual molecules C, H, which react with active oxygen O, can be removed without damaging the wiring layer inside the through hole.
O, N, etc. react with this O to form H ₂ O, CO ₂ , N ₂
It changes into volatile substances such as and is removed from the surface.

Note that the organic film used here is not limited to a polyimide film, and any organic film containing C, H, O, N, etc. that reacts with active oxygen O can be used.

Further, as a method for forming the wiring layer after cleaning, a conventional method may be used in which a thin film is deposited using a sputtering method, a vapor deposition method, or the like, and then patterned by photolithography.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIGS. 1A to 1F are diagrams showing the process of forming a wiring board according to an embodiment of the present invention.

First, as shown in FIG. 1a, a chromium layer is formed as a first wiring layer 2 on a glass substrate 1, and after patterning it by the usual photolithography method, a polyimide film 3 is formed to a thickness of 1.5 μm. Apply and bake at 135℃ for 30 minutes.

Subsequently, as shown in FIG. 1B, a photoresist 4 having a thickness of 1 μm is applied and exposed using a photomask 5 having a predetermined pattern to form a pattern latent image G.

Thereafter, as shown in FIG. 1c, the photoresist 4 and the polyimide film 3 are simultaneously developed and etched using a sodium silicate solution to form through holes h. The etching time at this time was 60 seconds.

Then, after peeling off the resist, 350°C 1
After several hours of heat treatment, the polyimide film is completely cured. At this time, a thin amount of residue O remains inside the through hole.

Thereafter, as shown in FIG. 1d, the surface of the substrate is irradiated with ultraviolet rays for 120 seconds to clean the through holes. Here, six 25W low-pressure mercury lamps were used for ultraviolet irradiation.

After removing the residue in the through hole h in this manner, an aluminum pattern is formed as the second wiring layer 6 as shown in FIGS. 1e and 1f. Here, FIG. 1f is a sectional view taken along the line AA in FIG. 1e. Also, the pattern width W1 of the first wiring layer, the pattern width W1 of the first wiring layer,
The pattern width W2 of the wiring layer is 90μm and 100μm, respectively.
The through hole is rectangular with one side W3 = 70 μm.

The first wiring layer and the second wiring layer of the wiring board thus formed are connected to terminals, a voltage is applied, and the current-voltage (I-V) characteristics are measured and the results are shown in Figure 2. . Here, the vertical axis is current and the horizontal axis is voltage.

For comparison, FIGS. 3 and 4 show the IV characteristics when the through-holes were not cleaned and when plasma cleaning was performed using oxygen plasma, respectively.

As is clear from the comparison between FIG. 2, FIG. 3, and FIG. 4, the wiring board formed by the method of the present invention has the first wiring layer and the second
It can be seen that the contact properties with the wiring layer are significantly improved.

Further, according to the method of the present invention, since it is only necessary to irradiate ultraviolet rays, no special equipment is required, and cleaning can be easily performed in a short time.

In the embodiments, an interlayer insulating film has been described, but it goes without saying that the present invention can also be applied to forming a contact hole in an element region in an insulating film formed on the surface of a substrate.

Furthermore, although a polyimide film was used as the insulating film in the embodiment, other organic insulating films are also applicable.

[Effects] As explained above, according to the present invention, when forming through holes in an organic insulating film, ultraviolet rays are irradiated after the through holes are drilled in the wet etching process. Multilayer wiring with good ohmic contact and high reliability can be obtained very easily.

[Brief explanation of the drawing]

1a to 1f are diagrams showing the manufacturing process of a multilayer wiring board according to an embodiment of the present invention, and FIG. 2 is a diagram showing current-voltage characteristics of a multilayer wiring formed by the method according to an embodiment of the present invention. 3 and 4 are diagrams showing current-voltage characteristics of a multilayer wiring board formed by a conventional method, and FIGS. 5a to 5d are manufacturing process diagrams of a conventional multilayer wiring board. 1... Glass substrate, 2... First wiring layer, 3...
...Polyimide film, 4...Photoresist, 5...
Photomask, G... pattern latent image, h... through hole.

Claims (1)

[Claims] 1. A method for manufacturing a multilayer wiring board in which an upper wiring layer and a lower wiring layer are connected through an opening in an interlayer insulation film made of an organic insulation film, comprising the steps of: forming an organic insulation film on the lower wiring layer; After forming a film and drilling holes (through holes) in it by wet etching, prior to forming the upper wiring layer,
A method for manufacturing a multilayer wiring board, comprising a cleaning step of removing residue within the openings by irradiating the surface of the board with ultraviolet rays. 2. The method of manufacturing a multilayer wiring board according to claim 1, wherein the organic insulating film is a polyimide film.