JPH06333797A - Method of aligning mask in transfer step - Google Patents

Abstract

PURPOSE:To provide a method of aligning a mask in a transfer step capable of readily and accurately correcting misalignment of the mask by simple means. CONSTITUTION:In a method of aligning a mask in a transfer step for transferring patterns formed on the mask to a basic material, the basic material and mask are respectively provided with alignment marks 60a, 60b, and also the alignment marks 60a, 60b are superimposed on each other to form a gap 61 between respective external forms, and the gap 61 is detected from the shape, thereby correcting misalignment of the mask.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mask alignment method in a transfer process, and more particularly to a mask alignment method in a transfer process for transferring a pattern formed on a mask onto a substrate.

[0002]

2. Description of the Related Art Some electronic component mounting boards for mounting electronic components such as semiconductor chips and connecting the electronic components to the outside have a large number of conductor circuit layers. One of the methods for manufacturing such an electronic component mounting substrate (hereinafter referred to as a multi-layer substrate) is to transfer a pattern formed on a mask by a photographic method or a printing method to a base material, and sequentially conduct conductors in a lower conductor circuit. There is a so-called build-up method of stacking circuits. Here, a conventional mask alignment method in a transfer process will be described below by taking a manufacturing process of a multilayer substrate as shown in FIGS. 10 and 11 as an example. The electronic component mounting boards shown in FIGS. 10 and 11 have a conductor circuit (hereinafter referred to as a P layer circuit) formed on the surface of an internal core material, and an insulating base material layer as an upper layer of the P layer circuit. And a conductor circuit (hereinafter referred to as an S layer circuit) formed via the insulating layer, and the P layer circuit and the S layer circuit are connected by a via formed so as to penetrate the insulating base material layer. Then, the S layer circuit and the via are formed by a series of steps as shown in FIGS.

First, a P layer circuit is formed on the surface of the core material in advance (a), and a transparent photosensitive resin is applied to the upper surface of the P layer circuit (b). Then, the photosensitive resin is exposed with a via forming mask on which a via pattern is formed (c). At this time, the mask is aligned with a transparent photosensitive resin as shown in FIG. Via the P layer circuit and the pattern of the vias of the mask. Then, the photosensitive resin is exposed to obtain an insulating base material layer in which a concave portion to be a via is formed at a desired position on the P layer circuit (d).

Next, a transparent dry film resist made of a photosensitive resin is attached to the upper surface of the insulating base material layer (e), and an S layer circuit forming mask having an S layer circuit pattern is formed. The dry film resist is exposed by (f), and the alignment of the mask at this time is formed on the insulating base material layer through the transparent dry film resist as shown in the parentheses in FIG. It is performed by superposing the concave portion of the via and the pattern of the S layer circuit of the mask. Then, the dry film resist is exposed to obtain a resist in which a concave portion to be an S layer circuit is formed in a desired portion including the concave portion of the via (g).

Finally, a via for connecting the P-layer circuit and the S-layer circuit and an S-layer circuit are formed by plating (h), and when unnecessary resist is peeled off, an insulating base material layer is formed on the upper layer of the P-layer circuit. A multilayer substrate is obtained in which S layer circuits are stacked via the above, and P layer circuits and S layer circuits are connected by vias (i).

[0006]

However, in the conventional mask alignment method, as shown in FIG.
The mask via pattern completely overlaps the P-layer circuit, the via recess completely overlaps the mask S-layer circuit pattern, and each has the same color, so each center should be accurately aligned. The mask could not be accurately aligned. For this reason, as shown in FIGS. 14 and 15, the P layer circuit and the via or the via and the S layer circuit are misaligned, and the P layer circuit and the S layer are formed by the via.
There are problems that the reliability of connection with the layer circuit is significantly impaired, the P layer circuit and the S layer circuit cannot be formed at accurate positions, and it is not possible to sufficiently meet the demand for finer conductor circuits.

On the other hand, as disclosed in, for example, Japanese Patent Publication No. 23490/1993, an alignment mark serving as an index of alignment is formed on each of the base material and the mask, and the alignment mark of the base material and the mask are formed. There is a method of aligning the substrate and the mask accurately by overlapping the alignment mark. In this configuration, the alignment marks of the base material and the mask are made to intersect with each other, and the area of the intersecting portion changes due to the displacement, and the displacement is corrected by detecting the area of the intersecting portion. Thus, the base material and the mask can be accurately aligned.

However, according to such a method,
The area of the intersecting portion has to be calculated, which requires a very troublesome work, and the direction and degree of the positional deviation have to be calculated by relatively moving the base material and the mask. A complicated process is required to correct the positional deviation, and the positional deviation cannot be easily corrected.

The present invention has been made in order to solve such a problem, and an object of the present invention is to perform mask alignment in a transfer process capable of easily and accurately correcting mask misalignment. The method is to provide by simple means.

[0010]

The means adopted by the present invention for solving the above problems will be described with reference to the reference numerals used in the drawings. The pattern 71 formed on the mask 70 will be described.
A method of aligning the mask 70 in a transfer step of transferring a substrate to a substrate, wherein the substrate and the mask 70 are provided with alignment marks 60a and 60b, respectively, and the alignment marks 60a and 60b are superposed on each other. By so doing, a gap 61 is formed between the respective outer shapes, and the positional deviation of the mask 70 is corrected by detecting the gap 61.

[0011]

According to the method of aligning the mask 70 in the transfer step of the present invention thus constructed, the alignment marks 60a and 60b provided on the base material and the mask 70, respectively, are superposed on each other. A gap 61 is formed between the outer shapes of 60a and 60b. Then, if the state of the gap 61 is confirmed visually or by an optical detector or the like, each alignment mark 60
The centers of a and 60b can be accurately aligned, and the mask 70 can be accurately aligned.

Further, depending on the state of the gap 61, it is possible to clearly confirm whether or not the positional deviation has occurred, and in the case where the positional deviation has occurred, the direction and degree thereof can be clearly confirmed. The position shift can be easily corrected without requiring any processing.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, one embodiment of a method of aligning the mask 70 in the transfer step according to the present invention will be described in detail with reference to the drawings. In the present embodiment, description will be given based on an example in which the alignment method of the present invention is adopted when the pattern 71 of the mask 70 is transferred by the photographic method to manufacture the multilayer substrate 100. The method is not limited to this, and can be adopted in a transfer process such as a printing method, and the base material to which the pattern 71 is transferred and the pattern 71 are not particularly limited.

1 and 2 show an example of the multi-layer substrate 100. In this multilayer substrate 100, a conductor circuit formed of copper foil, that is, a P layer circuit 20 is provided on the front and back of a core material 10 formed of a synthetic resin, and the P layer circuit 20 on the front and back is the core material 10. Are connected by through holes (not shown) that pass through the. Then, a conductor circuit, that is, an S layer circuit 40 is provided on the upper layer of each P layer circuit 20 via an insulating base material layer 30 to form a four-layer substrate having four conductor circuit layers (Fig. In Fig. 2, the lower two layers are omitted). In addition, the P layer circuit 2
0 and the S layer circuit 40 are connected by a via 50 penetrating the insulating base material layer 30. The vias 50 and S
The layer circuit 40 is formed by a series of steps including a step of transferring the pattern 71 of the mask 70 to the substrate by using the alignment method of the present invention as shown in FIG.
This series of steps will be described.

First, the P layer circuit 20 is formed on the surface of the core material 10.
And a ring-shaped alignment mark 60a is formed outside the P layer circuit 20 (a).
0 and the upper surface of the alignment mark 60a are coated with a transparent photosensitive resin 30a (b). Then, the photosensitive resin is exposed by the mask 70 for forming a via in which the pattern 71 of the via 50 and the alignment mark 60b are formed outside the pattern 71 (c).

Here, the alignment mark 60b of the mask 70 is a circular shape having an outer diameter smaller than the inner diameter of the ring-shaped alignment mark 60a formed on the core material 10, and when the mask 70 is accurately aligned, Figure 4
As shown in FIG.
The gap 61 is formed over the entire circumference between the inner circumference of the mask 70 and the outer circumference of the alignment mark 60b of the mask 70. If the mask 71 is not accurately aligned, as shown in FIG. 5, the entire circumference between the inner circumference of the alignment mark 60a of the core material 10 and the outer circumference of the alignment mark 60b of the mask 70 is covered. The gap 61 is not formed, and it is possible to easily confirm that the positional deviation has occurred, and the direction and degree thereof. Then, the gap 61 is formed over the entire circumference, that is, the mask 70.
Can be easily corrected to ensure accurate alignment.

Next, when the mask 70 is accurately aligned and the photosensitive resin 30a is exposed to light, the exposed portion of the photosensitive resin 30a is cured and remains to form the vias 50, which are recesses 51.
The insulating base material layer 30 in which is formed is obtained (d). Also,
At this time, a new circular alignment mark 60b is formed on the insulating base material layer 30 by the alignment mark 60b of the mask 70.

Next, a transparent dry film resist 80 made of a photosensitive resin is formed on the surface of the insulating base material layer 30.
a is attached (e), and the dry film resist 80a is exposed by the S layer circuit forming mask 70 in which the pattern 71 of the S layer circuit 40 and the alignment mark 60a are formed outside the pattern 71 (f). .

Here, the alignment mark 60b has a ring shape having an inner diameter larger than the outer diameter of the circular alignment mark 60b newly formed on the insulating base material layer 30, that is, the alignment mark 60a formed on the core material 10.
It has the same shape as. Then, when the mask 70 is accurately aligned, similarly, a gap 61 is formed over the entire circumference between the outer circumference of the alignment mark 60b of the insulating base material layer 30 and the inner circumference of the alignment mark 60a of the mask 70. The mask 70 can be accurately aligned. Before the dry film resist 80a is attached, the surface of the insulating base material layer 30 is subjected to surface roughening treatment and nucleation treatment as a pretreatment for the plating 90 described later. Is cloudy. Therefore, the alignment mark 60a of the core material 10 is not seen through the insulating base material layer 30, and only the alignment mark 60b of the insulating base material layer 30 and the alignment mark 60a of the mask 70 are accurately aligned. be able to. The surface of the insulating base material layer 30 is clouded, and the alignment mark 60b of the insulating base material layer 30 and the alignment mark 60a of the mask 70 are formed.
Is black, each alignment mark 60a, 6
The gap 61 between the outer shapes of 0b can be clearly confirmed. Therefore, the mask 70 can be reliably aligned.

Next, the dry film resist 80 is formed by the mask 70 for forming the S layer circuit which is accurately aligned.
When a is exposed to light, a resist 80 is obtained in which a concave portion 41 for forming the S layer circuit 40 is formed in a desired portion including the concave portion 51 of the via 50 (g).

Finally, the P layer circuit 20 is formed by plating 90.
And the S layer circuit 40
Are formed (h) and the unnecessary resist 80 is peeled off,
The S layer circuit 40 is laminated on the upper layer of the P layer circuit 20, and the multilayer substrate 100 in which the P layer circuit 20 and the S layer circuit 40 are connected by the via 50 is obtained (i). The insulating base material layer 30
A new alignment mark 60a other than the S layer circuit 40 is formed on the surface of, and a conductor circuit can be formed in a further upper layer based on this alignment mark 60a.

As described above, in the present embodiment, an example of the pair of alignment marks 60a and 60b, one of which is circular and the other of which is ring-shaped, is shown, but the shape of the alignment marks 60a and 60b is not particularly limited. Not something
For example, a square or triangle may be used.

Further, for example, as shown in FIG. 6, the lowermost layer alignment mark 60a has a shape in which a gap 61 is formed between the uppermost layer alignment mark 60b and the entire outer circumference of the lowermost layer alignment mark 60a. Alignment mark 6 further above the alignment mark 60b
0c may be sequentially overlapped as a shape that forms a gap 61 between the entire outer circumference of the lower layer alignment mark 60b.

Further, one alignment mark 60a
It is not necessary to form the other alignment mark 60b so as to form the gap 61 over the entire outer circumference of the first alignment mark 60a. For example, as shown in FIG. The other alignment mark 60b may be formed so as to form In this case, if the gaps 61 are formed at least at three places, the alignment marks 60a and 60b can be accurately aligned.

Further, for example, as shown in FIG. 8, when the alignment marks 60a and 60b are overlapped with each other, the alignment marks 60a and 60b may partially overlap each other. In this case, the gap 61 is formed by the outer shape portions of the alignment marks 60a and 60b which do not overlap each other.
The shape may be such that the positional deviation can be corrected by 1.

In this embodiment, the pattern of the mask 70 is transferred by the negative type photographic method, but the positive type photographic method may be used. In this case, the alignment marks 60a and 60b are formed. Is, for example, as shown in FIG.

[0027]

As described above in detail, in the mask alignment method in the transfer step of the present invention, the position of the mask is detected by detecting the gap formed between the contours of the aligned alignment marks. The deviation is corrected, and the position deviation of the mask and its direction and degree can be clearly confirmed.

Therefore, according to the present invention, it is possible to provide, by a simple means, a method for aligning a mask in a transfer process, which can easily and accurately correct the displacement of the mask.

[Brief description of drawings]

FIG. 1 is a partial plan view showing an example of a multi-layer substrate formed by a mask alignment method in a transfer process according to the present invention.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a process drawing showing a manufacturing process of the multilayer substrate shown in FIG.

FIG. 4 is a schematic diagram showing an example of an alignment mark.

5 is a schematic view showing a state in which the alignment mark shown in FIG. 4 is displaced.

FIG. 6 is a schematic diagram showing another example of an alignment mark.

FIG. 7 is a schematic diagram showing another example of an alignment mark.

FIG. 8 is a schematic diagram showing another example of an alignment mark.

FIG. 9 is a schematic diagram showing another example of an alignment mark.

FIG. 10 is a partial plan view showing an example of a multilayer substrate formed by a mask alignment method in a conventional transfer process.

11 is a sectional view taken along line BB in FIG.

12 is a process chart showing a manufacturing process of the multilayer substrate shown in FIG.

FIG. 13 is a schematic view showing a mask alignment method in a conventional transfer process.

FIG. 14 is a partial plan view showing an example of a multilayer substrate formed by a mask alignment method in a conventional transfer process.

FIG. 15 is a sectional view taken along line CC of FIG.

[Explanation of symbols]

 10 core material 20 P layer circuit 30 insulating base material layer 30a photosensitive resin 40 S layer circuit 41 recess 50 via 51 recess 60a alignment mark 60b alignment mark 60c alignment mark 61 gap 70 mask 71 pattern 80 resist 80a dry resist film 90 plating 100 Multilayer board

Claims (1)

[Claims] 1. A method of aligning a mask in a transfer step of transferring a pattern formed on a mask onto a base material, wherein the base material and the mask are each provided with an alignment mark, A method for aligning a mask in a transfer process, characterized in that a gap is formed between respective outer shapes by overlapping each other, and a positional deviation of the mask is corrected by detecting the gap.