JP2000181074A - Method for exposing photosensitive layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a photo via hole in a photosensitive insulating layer disposed on a built-up multilayer circuit board without forming pinholes. SOLUTION: A photosensitive insulating layer 12 disposed on a substrate is exposed with UV, through a 1st photo film 13 with a formed original image 13a corresponding to a photo via hole. The layer 12 is then exposed with UV through a 2nd photo film 14 with a formed original image 14a corresponding to the photo via hole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a photo-via hole in a photosensitive insulating layer of a build-up multilayer wiring board or a circuit pattern in a semiconductor chip. The present invention relates to a method for exposing a photosensitive layer, which is performed to form an exposure image corresponding to a via hole or a circuit pattern.

[0002]

2. Description of the Related Art In recent years, the packaging technology of LSIs has been increasing in size and integration, and the packaging technology of LSIs has been improved in order to downsize electronic devices. In SMT mass production technology, which is LSI mounting technology,
In the area array pad type package technology (CSP) in which the lead size of the 0.4 mm pitch is the limit, and the surface is mounted on the substrate using solder balls, the mounting area is almost equal to the chip size, and miniaturization is important. It is applied to portable information devices and the like.

In addition, a printed wiring board having a multilayered circuit pattern has been developed for such LSI mounting technology so that high-density mounting is possible even on a board on which the LSI is mounted. More recently, a build-up multilayer wiring board in which a circuit pattern formed by copper plating or the like and a photosensitive insulating layer are alternately laminated has been developed.

In such a build-up multilayer wiring board,
Photovia holes for electrically connecting circuit patterns are formed in the photosensitive insulating layer. The photovia hole is formed by a photoresist method or a laser method.

In the case of forming a photovia hole in a photosensitive insulating layer by a photoresist method, a photosensitive insulating resin is applied to a substrate such as a double-sided copper-clad laminate or a multilayer copper-clad laminate to apply a photosensitive insulating resin. After the layer is formed, the photosensitive insulating layer is exposed to ultraviolet light or the like through a photomask having an original image formed corresponding to the planar shape and planar position of the photovia hole, thereby exposing the photosensitive insulating layer. An image is formed and the exposed image is developed with a chemical solution to remove the exposed image portion and form a photovia hole.

[0006]

In such a method for manufacturing a photo via hole, a photo film is used as a photo mask, and an original image on the photo film is usually exposed at a magnification of 600 mJ with an ultraviolet ray at an equal magnification. It has become so. For this reason, the photo film has the same size as the substrate provided with the photosensitive insulating layer, and there is a problem that foreign matter, dirt, and the like easily adhere to the photo film. If foreign matter, dirt, and the like are attached to the photo film, the foreign matter, dirt, and the like are also exposed to the photosensitive insulating layer, and an exposed image corresponding to the foreign matter, dirt, and the like is formed. When an exposed image of such a foreign substance or the like is formed on the photosensitive insulating layer, the exposed image of the foreign substance or the like is also subjected to development processing in a subsequent development step, and a pinhole is formed in the photosensitive insulating layer. If the shape of the foreign matter is large, a large through hole is formed. Therefore, when a circuit pattern is formed by copper plating on the photosensitive insulating layer, the circuit pattern formed by the photosensitive insulating layer and the substrate are not covered. There is a possibility that insulation failure such as a short circuit may occur.

An object of the present invention is to solve such a problem, and an object of the present invention is to form an exposed image on a photosensitive layer by foreign matter even if the foreign matter adheres to a photomask such as a photo film. An object of the present invention is to provide a method for exposing a photosensitive layer, which can reliably form only a predetermined exposure image without fear of occurrence.

[0008]

According to the present invention, there is provided a method for exposing a photosensitive layer to an image having a predetermined shape. The method comprises the steps of: Preparing a first photomask and a second photomask respectively formed at the positions of, exposing the original image of the first photomask to the photosensitive layer, and then exposing the original image of the second photomask to the photosensitive layer It is characterized by.

The photosensitive layer is a photosensitive insulating layer provided on the build-up multilayer wiring board, and the exposed image corresponds to a planar shape of a photo via hole formed in the photosensitive insulating layer.

The original image formed on the second photomask conforms to the planar shape of the photovia hole portion formed on the photosensitive insulating layer, and the original image formed on the first photomask is 2 includes the entire original image of the photomask.

[0011]

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

In the method for exposing a photosensitive layer according to the present invention, when a build-up multilayer wiring board is manufactured, as shown in FIG. 1A, a photosensitive insulating layer 12 is laminated on a substrate (not shown).
This is performed to form a photo via hole of a predetermined shape at a predetermined position of the photo via hole. The substrate is composed of a double-sided copper-clad board or a multilayer copper-clad laminate. Photosensitive insulating layer 1
Reference numeral 2 is made of a negative photosensitive resin from which unexposed portions that are not exposed are removed.

The photosensitive insulating layer 12 laminated on the substrate has a first photo film 13 shown in FIG.
By using the second photo film 14 shown in FIG.
The photosensitive insulating layer 12 is formed by the first 1: 1 exposure with ultraviolet light using the first photo film 13 and the second 1: 1 exposure with ultraviolet light using the second photo film 14.
At a predetermined position, a non-photosensitive portion corresponding to the shape of the photovia hole is formed as an exposure image.

As shown in FIG. 1A, the first photo film 13 used for the first equal-size exposure is slightly larger than the planar shape of the photo via hole in order to form the photo via hole. An original image 13a, which is a circular light-shielding portion in a planar shape, is provided at a predetermined planar position. The first photo film 13 is disposed above the photosensitive insulating layer 12 in a state parallel to the photosensitive insulating layer 12 and, for example, has a higher exposure energy (about 600 mJ) in one conventional ultraviolet exposure. Small 400mJ
The photosensitive insulating layer 12 is irradiated with ultraviolet rays having the energy of 1 through the first photo film 13. As a result, the photosensitive insulating layer 12 is irradiated with ultraviolet rays through a portion other than the original image 13a formed on the first photo film 13,
An original image of the original image 13 a of the first photo film 13 is formed on the photosensitive insulating layer 12 as an exposure image.

In this case, on the first photo film 13,
If the fine foreign matter 15 such as dust adheres, the ultraviolet light does not pass through the portion where the foreign matter 15 is adhered.
A 1: 1 image of the foreign matter 15 is formed on the photosensitive insulating layer 12 as an exposure image.

Thereafter, as shown in FIG. 1B, a second photo film 14 is disposed above the photosensitive insulating layer 12 in a state parallel to the photosensitive insulating layer 12. On the second photo film 14, an original image 14a, which is a circular light-shielding portion having a planar shape in the same alignment state as the planar shape of the photovia hole, is provided at a predetermined planar position. The second photo film 14 has, for example, 400 m, which is the same as the exposure energy of the ultraviolet light at the time of the first exposure.
The photosensitive insulating layer 12 is irradiated with the ultraviolet light having the energy of J through the second photo film 14. As a result, the ultraviolet light transmitted through portions other than the original image 14 a provided on the second photo film 14
To form a 1: 1 image of the original image 14 a of the second photo film 14 on the photosensitive insulating layer 12 as an exposure image.

In this case, the original image 14a provided on the second photo film 14 has a shape matching the plane shape of the photo via hole formed in the photosensitive insulating layer 12, and the first photo film 13 Original image 1
3a is included in the original image 14a provided on the second photo film 14. As a result, the photosensitive insulating layer 1
2, the unexposed portions of the first film 13 which are not exposed by the original image 13a are the second photo films 1
4 is exposed by irradiating the ultraviolet rays transmitted around the original image 14. Therefore, only the region that is not irradiated with the ultraviolet rays by both the original image 13a of the first photo film 13 and the original image 14a of the second photo film 14 becomes the unexposed portion.

Similarly, the non-photosensitive portion formed on the photosensitive insulating layer 12 by the foreign matter 15 such as dust attached to the first photo film 13 is exposed to ultraviolet light transmitted through the second photo film 14. .

In this case, foreign matter 15 such as dust may adhere to the second photo film 14, but the foreign matter 15 adhered to the second photo film 14 may not be irradiated on the photosensitive insulating layer 12 by ultraviolet rays. Usually, in the first exposure step, the photosensitive layer is exposed to ultraviolet rays and is exposed, and there is almost no possibility that a non-photosensitive portion is formed on the photosensitive insulating layer 12 of the second photo film 15.

As a result, the photosensitive insulating layer 12
By performing the ultraviolet exposure twice using each of the photo films, only the portion of the second photo film 14 through which the ultraviolet light is not transmitted by the original image 14a is formed as an exposed image as a non-photosensitive portion. Even if the foreign matter 15 adheres to the first and second photo films 13 and 14, there is no possibility that an image exposed by the foreign matter 15 is formed on the photosensitive insulating layer 12.

As described above, when the photosensitive insulating layer 12 is exposed, the photosensitive insulating layer 12 is subjected to a developing treatment to remove a portion of the photosensitive insulating layer 12 that has not been exposed to ultraviolet rays, and to remove the photovia. A hole is formed. In this case, the original image 14 formed on the second photo film 14 in an alignment state corresponding to the formed photo via hole
Portions other than a are reliably exposed to ultraviolet light, and there is no possibility that a pinhole or the like is formed in the photosensitive insulating layer 12.

Thereafter, a circuit pattern formed by electrolytic plating is formed on the photosensitive insulating layer 12. At this time, a predetermined position of the circuit pattern is brought into a conductive state with the substrate by the photo via hole formed in the photosensitive insulating layer 12. Thereafter, a similar operation is repeated to obtain a build-up multilayer wiring board in which a plurality of circuit patterns are formed in a substrate shape while being insulated by the photosensitive insulating layer.

As described above, the two photo films 1
In the case where the photosensitive insulating layer 12 is exposed to ultraviolet light using each of 3 and 14 to form an exposed image, 1
Processing time may be longer than when an exposed image is formed by one exposure to ultraviolet light using a single photofilm. However, the photosensitive insulating layer 12 is formed by using two photo films 13 and 14, respectively.
Is exposed to ultraviolet light, the irradiation energy of the ultraviolet light at each exposure is made smaller than the irradiation energy of the ultraviolet light at the time of one exposure of ultraviolet light using a single photo film, thereby reducing the processing time. Can be shortened. Theoretically, when the photosensitive insulating layer 12 is exposed twice, the irradiation energy of the ultraviolet light in each exposure is the same as that of the ultraviolet light when the photosensitive insulating layer is exposed only once to form an exposed image. It is sufficient that the irradiation energy is one half of the irradiation energy.

In consideration of the processing time and the like, in practice, when the photosensitive insulating layer 12 is exposed twice, the irradiation energy of the ultraviolet rays in each exposure is determined by exposing the photosensitive insulating layer only once. The value is set to be slightly larger than one half of the irradiation energy of the ultraviolet light when forming an image.

In the above embodiment, the photosensitive insulating layer 12 is exposed twice using the two photo films 13 and 14, respectively.
The photosensitive insulating layer 12 may be exposed three or more times using three or more photo films. Further, in the above embodiment, the exposure method for forming the photovia hole in the photosensitive insulating layer in the build-up multilayer wiring board has been described. However, the present invention is also applicable to the case where the circuit pattern is exposed on the photosensitive resin layer. Can be applied.

[0026]

According to the method for exposing the photosensitive layer of the present invention, since the exposure is performed twice using each of at least two photomasks, foreign matters and the like adhering to the photomask are exposed. Is not likely to be formed on the photosensitive layer. In particular, without forming pinholes in the photosensitive insulating layer of the build-up multilayer wiring board,
Photovia holes can be formed.

[Brief description of the drawings]

FIGS. 1A and 1B are schematic views of processing steps in an embodiment of a photosensitive layer exposure method of the present invention.

[Explanation of symbols]

 12 Insulating photosensitive layer 13 First photo film 13a Original image 14 Second photo film 14a Original image

Claims (3)

[Claims] 1. A method of exposing an image of a predetermined shape to a photosensitive layer, comprising: a first photomask and a second photomask each having an original image corresponding to an exposure image formed on the photosensitive layer formed at a predetermined position;
A method for exposing a photosensitive layer, comprising preparing a photomask, exposing an original image of a first photomask to a photosensitive layer, and exposing the photosensitive layer to an original image of a second photomask. 2. The photosensitive layer is a photosensitive insulating layer provided on a build-up multilayer wiring board, and the exposed image corresponds to a planar shape of a photo via hole formed in the photosensitive insulating layer. Item 4. The method for exposing a photosensitive layer according to Item 1. 3. The original image formed on the second photomask conforms to the planar shape of a photovia hole portion formed on the photosensitive insulating layer, and the original image formed on the first photomask is 2. The method of exposing a photosensitive layer according to claim 1, wherein the entirety of the original image of the second photomask is included.