JP2005203710A - Method for forming via hole of multilayer structure component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming the via hole of a multilayer structure component in which the via hole having a desired fine hole diameter can be formed in an insulating layer which is thick enough to have sufficient withstand voltage reliability. <P>SOLUTION: In the method for forming the via hole, a 1st photosensitive insulating material sheet 31 is laminated on a base substrate 2 and a 1st conductor 4, and an unsintered 1st via hole 71 is formed therein by exposure and development and then sintered to form a 1st sintered insulating film 33. Then a 2nd photosensitive insulating material sheet 32 is laminated thereupon, and an unsindered 2nd via hole 72 is formed therein by exposure and development and then sintered to form a 2nd sintered insulating film 34. Consequently, an inter-conductor insulating layer 3 is formed which has a via hole 7 with a high aspect ratio. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for forming a via hole in an insulating layer of a multilayer structure component such as a multilayer chip inductor.

  Conventionally, in this type of multilayer structure component, the first electrode (or first conductor) is formed on one surface of the insulating layer, and the second electrode (or second conductor) is formed on the other surface. In addition, the first electrode and the second electrode are electrically insulated through an insulating layer. A via hole is provided at a predetermined position of the insulating layer, the via hole is filled with a conductive material, and the first electrode and the second electrode are electrically connected through the conductive material. .

  In recent years, a method has been proposed in which a fine via hole is accurately formed by patterning a photosensitive insulating material by a photolithography method (see, for example, Patent Document 1 and Patent Document 2).

  Specifically, as shown in FIG. 12, a first electrode 131 is formed on a support substrate 130 (FIG. 12A), and a ceramic slip material containing a photocurable monomer is formed thereon. Such a photosensitive insulating material 132 is formed into a sheet shape by, for example, a printing method (FIG. 12B). Then, exposure corresponding to the pattern of the via hole is performed using a photomask, the portions other than the non-exposed portion 133 are cured (FIG. 12C), and the non-exposed portion 133 is removed by development, thereby unburned. A via hole 134 is formed in the resulting photosensitive insulating material sheet 132 (FIG. 12D). Further, the unsintered photosensitive insulating material sheet 132 is sintered to form (sinter) the insulating layer 135 having a desired via hole 134 (FIG. 12E). Then, the space of the via hole 134 is filled with a conductive material 136 such as a conductive paste and solidified, and the conductor film is patterned at a position covering the via hole to form the second electrode 137 (FIG. 12F). )). Accordingly, the first electrode 131 and the second electrode 137 are electrically connected by the conductive material 136 filled in the via hole 134.

Japanese Patent Laid-Open No. 7-297077 JP-A-8-186379

However, the above-described via hole forming method has the following problems.
That is, since the photosensitive insulating material sheet 132 such as a ceramic slip material containing a photocurable monomer shrinks as a whole when sintered, the film thickness after sintering is as follows. It becomes thinner than the unsintered photosensitive insulating material sheet 132. For this reason, in order to ensure sufficient withstand voltage reliability or insulation performance of the insulating layer as a product after sintering, the unsintered photosensitive insulating material sheet 132 is made thick and sintered. It is necessary to ensure the thickness of the subsequent photosensitive insulating material sheet 132.
In addition, with the increase in the density of multilayer structure components, there is a tendency to demand miniaturization, higher density, and higher accuracy of patterns such as electrodes and wirings. In order to satisfy such a demand, it is necessary to make the via hole 134 finer while ensuring predetermined conductivity.

  However, it is difficult to form a fine via hole 134 having a hole diameter (diameter) in such a thick unsintered photosensitive insulating material sheet 132 with an accurate shape and dimensional reproducibility.

  That is, as shown in FIG. 13, when the pattern of the via hole 134 is exposed to the photosensitive insulating material sheet 132 by a photolithography method, the film of the photosensitive insulating material sheet 132 is caused by exposure conditions, development conditions, and the like. As the thickness increases, the error (variation or difference in size) of the hole diameter of the latent image 133 tends to increase, and the via hole 134 having a uniform hole diameter in the thickness direction is accurately formed. It was difficult.

  Further, when the photosensitive insulating material sheet 132 having the unsintered via hole 134 shown in FIG. 14A is sintered, the photosensitive insulating material sheet 132 such as a ceramic slip material generally contracts, and FIG. As shown in b), the sintered insulating film 135 obtained after the sintering becomes thinner as a whole, and the size of the void such as the via hole 134 is expanded by the amount of shrinkage due to the shrinkage. As a result, the hole diameter φ <b> 2 of the via hole 134 becomes larger than the hole diameter φ <b> 1 when not sintered after sintering. And the expansion of the hole diameter after such sintering becomes so remarkable that the film thickness of the photosensitive insulating material sheet 132 becomes thick.

  Therefore, in order to form an insulating layer (sintered insulating film 135) having sufficient withstand voltage reliability, if the unsintered photosensitive insulating material sheet 132 is thickened in anticipation of shrinkage after sintering, Although the sintered insulating film 135 having a desired thickness can be obtained later, the via hole 134 after sintering becomes significantly larger than the desired hole diameter. As a result, the hole diameter as described above is contradictory to a request to make the hole diameter as thin as possible within a range not impairing conductivity. If the sintered via hole 134 is enlarged as described above, a sufficient space cannot be made between the via hole 134 and the surrounding electrode pattern (not shown), or the via hole 134 has a surrounding electrode pattern. May cause short circuit failure.

On the other hand, in order to obtain a via hole 134 having a desired narrow hole diameter even when enlarged by sintering, the via hole 134 having a smaller hole diameter is taken into consideration with an unsintered photosensitive property in consideration of the expansion ratio of the hole diameter. It may be possible to form the insulating material sheet 132 in advance.
However, accurate exposure and development of the thin hole-shaped via hole 134 on the thick unsintered photosensitive insulating material sheet 132 by the photolithography method as shown in FIG. This means that the via hole 134 having a small length and a long length d is formed. In other words, the via hole 134 having a high aspect ratio (AR = d / φ) is formed. This is actually difficult because it faces the limit of processing limit in the photolithography method as described above.

  The present invention has been made in order to solve the above-described problems, and is a multilayer structure component capable of forming a via hole having a desired fine hole diameter in an insulating layer having a sufficient voltage withstand voltage reliability. An object is to provide a method for forming a via hole.

In order to solve the above-mentioned problems, the invention of claim 1 includes a first conductor that penetrates an insulating layer having a predetermined thickness and is laminated, and a second conductor that is laminated on the insulating layer. A method of forming a via hole in a multilayer structure component for forming a via hole for electrically connecting the first and second layers, a first step of forming an unsintered photosensitive insulating material layer thinner than the length of the via hole, and the first step A second step of exposing the unsintered photosensitive insulating material layer formed in step 2 corresponding to the pattern of the via hole, and developing the unsintered photosensitive insulating material layer exposed in the second step to Including a third step of forming a sintered via hole portion and a fourth step of sintering the photosensitive insulating material layer that has undergone the third step to form a thin insulating layer having a via hole portion. Repeating the process from 1st process to 4th process multiple times Accordingly, with an insulating layer of a predetermined thickness using a plurality of thin insulating layers laminated, and a configuration of forming a via hole by a plurality of via hole in communication.
By such a configuration, by forming the unsintered photosensitive insulating material layer, and repeating the first to fourth steps of sintering after exposing and developing the via hole portion, by stacking a plurality of thin insulating layers, An insulating layer having a predetermined thickness can be formed, and a via hole can be formed by a plurality of communicating via hole portions.

According to a second aspect of the present invention, in the method of forming a via hole for a multilayer structure component according to the first aspect, in the second step, the via hole portion is formed such that the diameter of the via hole portion is equal to or greater than the thickness of the photosensitive insulating material layer. It was set as the structure which performs the exposure corresponding to this pattern.
With such a configuration, when developing is performed in the third step, a via hole having a desired hole diameter can be formed even if a residue is generated in the via hole. For this reason, the hole diameter of the via hole provided in the unsintered photosensitive insulating material layer by the photolithography method can be set to an aspect ratio of 1 or less that enables accurate patterning.

  The invention according to claim 3 is the method for forming a via hole in a multilayer structure component according to claim 1 or 2, wherein the photosensitive insulating material layer is formed by applying a photosensitive glass paste. .

  Further, the invention of claim 4 is the method for forming a via hole for a multilayer structure component according to any one of claims 1 to 3, wherein the step of taking the first step to the fourth step is repeated a plurality of times. A photosensitive insulating material layer having a thermal contraction rate different from that of the photosensitive insulating material layer used at another time is used as the photosensitive insulating material layer used at any one time.

  As described above, according to the present invention, a plurality of thin insulating layers form an insulating layer having a predetermined thickness and a plurality of communicating via hole portions form a predetermined length of via holes. Even if a via hole portion having a high aspect ratio is not formed, a high aspect ratio via hole can be formed as a whole. Moreover, since each photosensitive insulating material layer is thin, the hole diameter of the via hole portion of the thin insulating layer after sintering hardly expands. Therefore, the finally obtained insulating layer has a very high aspect ratio. A via hole can be obtained. As a result, there is an excellent effect that it is possible to realize a multilayer structure component having a via hole having a desired fine and accurate hole diameter and having an insulating layer having a thickness having sufficient withstand voltage reliability.

  In particular, according to the invention of claim 2, when developing is performed in the third step, even if a residue is generated in the via hole portion, a via hole portion having a desired hole diameter can be formed. The hole diameter of the via hole provided in the unsintered photosensitive insulating material layer can be set to an aspect ratio of 1 or less that enables accurate patterning.

  The best mode of the present invention will be described below with reference to the drawings.

  FIG. 1 is an external view of a multilayer structure part having a via hole formed by the via hole forming method according to the first embodiment of the present invention, and FIG. 2 is an insulation diagram in which a via hole is provided in the multilayer structure part of FIG. It is arrow AA sectional drawing which extracts and shows the part of the layer.

  As shown in FIG. 1, this multilayer structure component is a multilayer structure component having an external electrode 1 on its surface. As shown in FIG. 2, the support substrate 2 and an insulation having a predetermined thickness provided thereon are provided. An inter-conductor insulating layer 3 as a layer; a first conductor 4 provided on the lower surface of the inter-conductor insulating layer 3; a second conductor 5 provided on the upper surface of the inter-conductor insulating layer 3; 6 constitute a multilayer structure 100 as a main part.

  The support substrate 2 is a general substrate such as a ceramic substrate, and the first and second conductors 4 and 5 are stacked on the support substrate 2.

  The first conductor 4 is provided on the surface of the support substrate 2, and as will be described later, a photosensitive conductor material is selectively exposed and developed by photolithography using a photomask and patterned. It is formed by sintering.

  The inter-conductor insulating layer 3 is a first insulating thin layer formed by applying or printing a first photosensitive insulating material sheet 31 (described later) on the support substrate 2 and the first conductor 4 and sintering the sheet. The second insulating insulating film 33 and the second insulating insulating film 33 are coated with a second photosensitive insulating material sheet 32 or printed on the first sintered insulating film 33 and sintered to form a second thin insulating layer. The sintered insulating film 34 is formed by laminating to a predetermined thickness. The via hole 7 having a predetermined hole diameter penetrates the inter-conductor insulating layer 3 composed of the first sintered insulating film 33 and the second sintered insulating film 34, and is formed by the conductive material 8 filled therein. The first conductor 4 and the second conductor 5 are electrically connected.

  In the inter-conductor insulating layer 3, the layer thickness in the sintered state is sufficiently thick so that sufficient withstand voltage reliability between the first conductor 4 and the second conductor 5 can be obtained. In such a thick inter-conductor insulating layer 3, a via hole 7 having a thin, high aspect ratio, small error, and an accurate dimension that is difficult or impossible to form by a conventional general method. Is formed.

  The second conductor 5 is patterned on the upper surface of the inter-conductor insulating layer 3 by selectively exposing and developing a photosensitive conductor material by a photolithography method using a photomask, similarly to the first conductor 4. It is formed by sintering it.

  The upper surface insulating layer 6 is provided on the uppermost layer of the multilayer structure so as to cover the upper surface of the second conductor 5 and almost the entire upper surface of the inter-conductor insulating layer 3. 5 or the upper surface of the inter-conductor insulating layer 3 or the mechanical strength of the multilayer structure is reinforced by the upper surface.

The multilayer structure having the via hole 7 described above is manufactured by the following process.
FIG. 3 is a process diagram showing a method of forming the first conductor, and FIG. 4 is a process diagram showing the first to fourth processes.

First, as shown in FIG. 3, a step of forming the first conductor 4 on the support substrate 2 is executed.
That is, the negative photosensitive conductive material 41 is printed or applied on the support substrate 2 (FIG. 3A). Then, exposure corresponding to the pattern 21a of the first conductor 4 is performed by a photolithography method using the photomask 21 (FIG. 3B). Subsequently, the photosensitive conductor material 41 having the exposed portion 43 of the first conductor 4 is developed to remove a portion other than the exposed portion 43 (FIG. 3C), and the first conductor 4 is sintered to be first. The conductor 4 is formed (FIG. 3D).

In this state, as shown in FIG. 4, the first to fourth steps are executed.
That is, the first step is performed to print or apply a negative photosensitive insulating material such as a photosensitive insulating paste on the support substrate 2 on which the first conductor 4 is formed, and A first photosensitive insulating material sheet 31 is formed as a photosensitive material insulating layer thinner than the length of the via hole 7 (FIG. 4A). In addition, as this 1st photosensitive insulating material sheet 31 and the 2nd photosensitive insulating material sheet | seat 32 mentioned later, the photosensitive formed by knead | mixing the ceramic and the low melting glass with the organic binder containing the photocurable monomer, for example. Sex paste etc. can be used. Alternatively, a ceramic slip material obtained by kneading ceramics or the like in a generally binder having photosensitivity can also be used.

  Then, the second step is executed, and the first photosensitive insulating material sheet 31 is exposed by the photolithography method using the photomask 22 except for the pattern 22a corresponding to the first via hole portion 71 ′ described later. Thus, a non-exposed portion 73 is obtained (FIG. 4B).

  Subsequently, the third step is performed, the unsintered first photosensitive insulating material sheet 31 having the non-exposed portion 73 is developed, and the non-exposed portion 73 is removed, whereby unsintered first 1 via hole portion 71 'is formed (FIG. 4C).

Then, the fourth step is performed to sinter the unsintered first photosensitive insulating material sheet 31, thereby the first sintering as a thin insulating layer having the first via hole portion 71. An insulating film 33 is formed (FIG. 4D).
In the fourth step, the diameter of the first via hole portion 71 is larger than the diameter of the unsintered first via hole 71 ′ due to the thermal contraction of the first photosensitive insulating material sheet 31. However, since the film thickness of the first photosensitive insulating material sheet 31 alone is thin, the enlargement ratio of the diameter of the first via hole portion 71 after sintering is such that the inter-conductor insulating layer 3 is made of one thick photosensitive film. This is smaller than the conventional general method of forming the insulating material sheet by sintering.

Then, the process of completing the first to fourth processes is repeated once more.
FIG. 5 is a process diagram showing the first to fourth steps for the second time.
That is, the first step is executed again, and a negative photosensitive insulating material is printed or applied on the first sintered insulating film 33 to form a photosensitive material insulating layer thinner than the length of the via hole 7. A second photosensitive insulating material sheet 32 is formed (FIG. 5A).
Then, in the second step, the second photosensitive insulating material sheet 32 is exposed by the photolithography method using the photomask 23 except for the pattern 23a corresponding to the second via hole portion 72 ′ described later, and is not exposed. A portion 74 is obtained (FIG. 5B).
Subsequently, in the third step, the second photosensitive insulating material sheet 32 having the non-exposed portion 74 is developed and the non-exposed portion 74 is removed, thereby forming a second via hole portion 72 ′ ( FIG. 5 (c)).
Then, in the fourth step, the second photosensitive insulating material sheet 32 is sintered to form the second sintered insulating film 34 as a thin insulating layer having the second via hole portion 72 (FIG. 5). (D)). Also in this step, as in the first fourth step, the second via hole 72 ′ has an unsintered second via hole 72 ′ due to thermal contraction of the second photosensitive insulating material sheet 32. However, the expansion ratio of the hole diameter of the second via hole portion 72 after sintering is the conventional method in which the inter-conductor insulating layer 3 is formed by sintering a single sheet of photosensitive insulating material. Small compared to the general method.
As a result, the second sintered insulating film 34 is laminated on the first sintered insulating film 33 to form the inter-conductor insulating layer 3, and the first and second via hole portions 71 and 72 communicate with each other. Thus, the via hole 7 is formed.

In this state, the step of forming the second conductor and the step of forming the upper surface insulating layer are sequentially performed.
FIG. 6 is a process diagram showing a method of forming the second conductor, and FIG. 7 is a cross-sectional view showing the produced multilayer structure.
That is, as shown in FIG. 6, a negative photosensitive conductive material 42 is printed or applied on the inter-conductor insulating layer 3 (FIG. 6A). At this time, the photosensitive conductor material 42 is also filled into the via hole 7 formed by the first and second via hole portions 71 and 72. Then, the pattern 24a corresponding to the second conductor 5 is exposed by a photolithography method using the photomask 24 to obtain an exposed portion 52 (FIG. 6B). Subsequently, the photosensitive conductor material 42 having the exposed portion 52 is developed to remove portions other than the exposed portion 52 (FIG. 6C), and sintered to form the second conductor 5 (FIG. 6). 6 (d)).

  Then, as shown in FIG. 7, the upper surface insulating layer 6 is formed so as to cover almost the entire upper surface of the inter-conductor insulating layer 3. Thereafter, the wafer-like multilayer structure is divided into each chip (multilayer structure 100 in FIG. 1) by dicing, and the external electrode 1 is assembled on the surface of each chip to produce the multilayer structure component shown in FIG.

Next, an application example of the via hole forming method of this embodiment will be described.
FIG. 8 is a process diagram for explaining an example of use of this embodiment.
Here, a case where a via hole having a hole diameter of 90 [μm] is formed in an insulating layer between conductors having a film thickness of 30 [μm] capable of obtaining sufficient withstand voltage reliability is exemplified, and a photosensitive insulating material is used. When the thickness of the sheet is sintered, it becomes half that when unsintered (heat shrinkage rate is 1/2). In addition, the enlargement ratio of the hole diameter of the via hole due to the sintering of the photosensitive insulating material sheet increases corresponding to the thickness, but here, for ease of understanding, it is assumed that it is “2” regardless of the thickness. explain.

Sintering a photosensitive insulating material sheet having a thickness of 60 [μm] having a via hole having a hole diameter of 90 [μm], assuming a heat shrinkage of the thickness, firing of the obtained thickness of 30 [μm] is performed. The diameter of the via hole in the insulating film becomes 180 [μm], which causes a short circuit. Therefore, assuming that the hole diameter is enlarged, it is conceivable to sinter a photosensitive insulating material sheet having a thickness of 60 [μm] having a via hole having a hole diameter of 45 [μm]. It is difficult in processing to form a fine via hole with a precise shape and dimensional reproducibility in a thick unsintered photosensitive insulating material sheet. In order to accurately reproduce the shape and dimensions, it is necessary to set the aspect ratio AR of the via hole of the unsintered photosensitive insulating material sheet to “1” or less.
Therefore, by utilizing the via hole forming method of this embodiment, using a photosensitive insulating material sheet having a low aspect ratio via hole portion that can be processed, an interconductor insulating layer having a desired film thickness of 30 [μm], A via hole having a hole diameter of 90 [μm] can be formed.

  That is, as shown in FIG. 8, the first to third steps are performed to expose and develop the first photosensitive insulating material sheet 31, and the first unsintered first hole having a pore diameter of 45 [μm] is obtained. A via hole portion 71 'is formed (FIG. 8A). At this time, since the film thickness of the first photosensitive insulating material sheet 31 is 30 [μm] and the hole diameter of the first via hole portion 71 ′ is 45 [μm], the aspect ratio of the first via hole portion 71 ′ is AR = 30/45 = 0.71 ′ <1. As described above, since the aspect ratio is 1 or less, the shape and size of the unsintered first via hole portion 71 ′ can be accurately formed by using the photolithography method.

  And a 4th process is performed and the unsintered 1st photosensitive insulating material 3 is sintered, and the 1st sintered insulating film 33 is obtained (FIG.8 (b)). At this time, shrinkage with a heat shrinkage factor of 1/2 occurs, and the film thickness of the completed first sintered insulating film 33 is 15 [μm]. Further, along with the shrinkage, the hole diameter of the first via hole portion 71 after sintering is enlarged to 90 [μm].

  The above first to third steps are repeated again, and the second photosensitive insulating material sheet 32 is applied or printed on the first sintered insulating film 33 (FIG. 8C), and the first photosensitive insulating film 33 is applied. Similarly to the conductive insulating material sheet 31, the second photosensitive insulating material sheet 32 is exposed and developed by photolithography to form an unsintered second via-hole portion 72 ′ having a hole diameter of 45 [μm]. (FIG. 8D). At this time, the unsintered second via hole portion 72 ′ is a term that penetrates through the second photosensitive insulating material sheet 32 that has entered the first via hole portion 71. Therefore, since the aspect ratio is AR = 45/45 = 1, the unsintered second via-hole portion 72 ′ can also be formed in an accurate shape and size using the photolithography method.

Then, the fourth step is executed to sinter the unsintered second photosensitive insulating material sheet 32 to obtain the second sintered insulating film 34 provided with the second via hole portion 72. (FIG. 8E) At this time as well, as in the case of the first photosensitive insulating material sheet 31, the film thickness of the completed second sintered insulating film 34 is 15 [μm]. Further, the hole diameter of the second via hole portion 72 after sintering is also expanded to 90 [μm].
Thus, by repeating the first to fourth steps, the second sintered insulating film 34 is further sintered on the first sintered insulating film 33, and the first and second sintered insulating films are then sintered. The inter-conductor insulating layer 3 having a thickness of 30 [μm] formed by laminating 33 and 34 can be produced. Thereby, the via hole 7 having a length (depth) of 30 [μm] in which the first via hole portion 71 and the second via hole portion 72 communicate with each other and a hole diameter of 90 [μm] can be formed.
By the way, the aspect ratio of the via hole 7 is 30/90, which is about 0.3. On the other hand, as in the prior art, a photosensitive insulating material sheet having a thickness of 60 [μm] having a via hole having a hole diameter of 90 [μm] is sintered and sintered to a thickness of 30 [μm]. When a via hole having a hole diameter of 180 [μm] is formed in the bonding insulating film, the aspect ratio of the completed via hole is 30/180, which is about 0.17. Therefore, the aspect ratio of the via hole 7 formed in this embodiment is very high compared to the aspect ratio of the via hole formed by the prior art.

  As described above, according to this embodiment, by sintering the first photosensitive insulating material sheet 31 having the first via hole portion 71 ′ having a low aspect ratio that can ensure accurate shape reproducibility, A first sintered insulating film 33 in which expansion of the hole diameter of the first via hole portion 71 after sintering is suppressed is produced, and a second photosensitive insulation having a second via hole having the same low aspect ratio is formed thereon. Since the material sheet 32 is sintered and the second sintered insulating film 34 having the second via hole portion 72 having a small hole diameter is laminated, the via hole 7 having a high aspect ratio is formed on the inter-conductor insulating layer 3 having a desired thickness. Can be formed. As a result, it is possible to realize a multilayer structure component including the via conductor 7 having a desired fine and accurate hole diameter and including the inter-conductor insulating layer 3 having a thickness having sufficient withstand voltage reliability.

Next explained is the second embodiment of the invention.
FIG. 9 is an end view showing a second step of the via hole forming method according to the second embodiment of the present invention.
The via hole forming method of this embodiment is different from the first embodiment in that the exposure is performed in the second step so that the hole diameter of the non-exposed portion of the via hole portion is equal to or larger than the thickness of the photosensitive insulating material layer.

Specifically, as shown in FIG. 9, the diameter D of the via hole pattern 22a (23a) of the photomask 22 (23) is set to the first photosensitive insulating material sheet 31 (second photosensitive insulating material sheet 32). The thickness is set to be equal to or greater than T and exposure is performed.
When the diameter D of the via hole pattern 22a (23a) of the photomask 22 (23) is smaller than the thickness T of the first photosensitive insulating material sheet 31 (second photosensitive insulating material sheet 32), Although the diameter of the non-exposed portion 73 (74) itself becomes a desired value, when the non-exposed portion 73 (74) is developed in the third step, as shown by a broken line in FIG. Residue M of the photosensitive insulating material remains in 71 ′ (second via hole portion 72 ′), and the hole diameter of first via hole portion 71 ′ (second via hole portion 72 ′) may be smaller than a desired value. Because. The residue M not only makes the hole diameter of the first via hole portion 71 ′ (second via hole portion 72 ′) non-uniform but may also block the first via hole portion 71 ′ (second via hole portion 72 ′).
Therefore, as in this embodiment, the diameter D of the via hole portion pattern 22a (23a) of the photomask 22 (23) is set to the thickness T of the first photosensitive insulating material sheet 31 (second photosensitive insulating material sheet 32). After the exposure is set as described above, the non-exposed portion 73 (74) is removed in the third step, whereby the residue M is formed in the first via hole portion 71 ′ (second via hole portion 72 ′). Even if it occurs, a via hole portion having a desired hole diameter completely penetrating the first photosensitive insulating material sheet 31 (second photosensitive insulating material sheet 32) can be formed. Therefore, the hole diameter of the first via hole portion 71 ′ (second via hole portion 72 ′) can be reliably reduced to an aspect ratio of 1 or less by photolithography.

Next explained is the third embodiment of the invention.
FIG. 10 is an end view showing the main steps of the third embodiment of the present invention.
In the via hole forming method of this embodiment, when the steps of the first to fourth steps are repeated twice, the thermal shrinkage is different from the thermal shrinkage rate of the first photosensitive insulating material sheet 31 used in the first time. The second photosensitive insulating material sheet 32 having a rate is different from the first and second embodiments in that it is used for the second time.

In this embodiment, the first photosensitive insulating material sheet 31 has an unsintered film thickness of about 30 [μm] and a thermal contraction rate of about 0.50, and the second photosensitive insulating material sheet 32. Applies a non-sintered film thickness of 32 [μm] and a thermal shrinkage of about 0.59, and the unsintered first and second via hole portions 71 ′ and 72 ′ are applied. Both pore diameters were set to 45 [μm]. That is, the thermal contraction rate of the first photosensitive insulating material sheet 31 is set higher than the thermal contraction rate of the second photosensitive insulating material sheet 32.
Then, in the first step, a first sintered insulating film 33 (FIG. 10A) formed by sintering the first photosensitive insulating material sheet 31 is formed, and in the second step, The second photosensitive insulating material sheet 32 was laminated and sintered to form a second sintered insulating film 34 (FIG. 10B), thereby constructing the inter-conductor insulating layer 3.

  By the way, the difference in thermal shrinkage is due to the difference in the ratio between the ceramic contained in the insulating paste and the low melting point glass. That is, the first photosensitive insulating material sheet 31 has a higher ratio of low-melting glass than the second photosensitive insulating material sheet 32. Thus, the wettability of the 1st photosensitive insulating material sheet 31 and the support substrate 2 can be improved by making the ratio of low melting glass high. On the other hand, it is assumed that the shrinkage rate tends to increase as the ratio of the low melting point glass increases.

  However, as in this embodiment, the first photosensitive insulating material sheet 31 that requires good wettability with respect to the support substrate 2 or so-called biting with respect to the first conductor 4 has wettability and the like. The photosensitive insulating paste is made of a material having a good thermal resistance (that is, a photosensitive insulating paste having a high thermal shrinkage rate). On the other hand, the shrinkage rate is suppressed more than the wettability and the shape reproducibility in the photolithography process. For the second photosensitive insulating material sheet 32 that is expected to have a better quality, a photosensitive insulating paste of such a material (that is, a photosensitive insulating paste having a low thermal shrinkage rate) is used. By using it, durability and reliability as a product such as a so-called bite against the support substrate 2 or the first conductor 4 of the inter-conductor insulating layer 3 in the manufactured multilayer structure component is further improved. It can be a thing.

Here, an experimental example performed by the inventor will be described.
FIG. 11 is a table showing the experimental results.
As shown in FIG. 11, ten samples of samples 1 to 10 were prepared, and an experiment was performed in which the samples were sintered in the above-described process. At this time, the printing thickness of the unsintered first photosensitive insulating material sheet 31 was 30.4 [μm] on the average of all 10 samples. Therefore, the average aspect ratio of the unsintered first via hole at this time is 30.4 / 45 = 0.68 <1.

  And when this 1st photosensitive insulating material sheet 31 was sintered, the thickness of the 1st sintered insulating film 33 became 15.1 [micrometers] on average, and the thermal contraction rate of the film thickness at this time Was 0.496 (about 1/2) on average. The hole diameter of the first via hole portion 71 (71 ′) was 45 [μm] when formed in the unsintered first photosensitive insulating material sheet 31. When one sintered insulating film 33 was obtained, the average of all 10 samples was 92.7 [μm]. Therefore, the enlargement ratio of the hole diameter at this time was 2.06 times on average.

  Moreover, about the unsintered 2nd photosensitive insulating material sheet 32, the printing thickness was 31.8 [micrometers] on the average of all the 10 samples. Therefore, the average aspect ratio of the unsintered second via hole at this time is 31.8 / 45 = 0.71 <1.

  And when this 2nd photosensitive insulating material sheet | seat 32 was sintered, the thickness of the 2nd sintered insulating film 34 became 18.7 [micrometers] on average, and the thermal contraction rate of the film thickness at this time is The average was 0.588. The hole diameter of the second via hole portion 72 (72 ′) was 45 [μm] when formed in the unsintered second photosensitive insulating material sheet 32. In the case of 2 sintered insulating films 34, the average of all 10 samples was 78.1 [μm], and the enlargement ratio of the hole diameter at this time was 1.73 times on average.

  The overall thickness of the inter-conductor insulating layer 3 formed by sequentially sintering and laminating the first sintered insulating film 33 and the second sintered insulating film 34 is 15.1 + 18.7 = 33. .8 [μm]. At this time, the average hole diameter of the continuous via hole 7 composed of the first via hole and the second via hole was 78.1. Therefore, the average aspect ratio of the via hole of the completed interconductor insulating layer 3 was 33.8 / 78.1 = about 0.43.

Thus, according to this embodiment, not only the so-called biting of the inter-conductor insulating layer 3 with respect to the support substrate 2 or the first conductor 4 is improved, but also the unsintered individual photosensitive insulating material sheet 31. 32, the aspect ratio of the via hole formed by photolithography can be set lower than 1 as 0.68 and 0.71, so that an accurate hole diameter can be reliably exposed and developed. . Furthermore, in the interconductor insulating layer 3 completed by sequentially sintering and laminating the plurality of photosensitive insulating material sheets 32, a via hole constituted by a first via hole portion 71 and a second via hole portion 72 is formed. 7 can be suppressed to an average of about 85.4 [μm].
Since other configurations, operations, and effects are the same as those in the first and second embodiments, description thereof is omitted.

In addition, this invention is not limited to the said Example, A various deformation | transformation and change are possible within the range of the summary of invention.
For example, in the above embodiment, the case where the first to fourth steps are repeated twice to produce an inter-conductor insulating layer made of two sintered insulating films has been described. However, the first to fourth steps are performed three times. By repeating the above, the inter-conductor insulating layer may be composed of a larger number of sintered insulating films than in the above embodiment. By such a method, a via hole portion having a small hole diameter while having an aspect ratio of 1 or less can be formed in an extremely thin photosensitive insulating material sheet. Therefore, the finished inter-conductor insulating layer is much more than the via hole of the above embodiment. A high aspect ratio via hole can be formed.

  In addition, the materials of the first photosensitive insulating material sheet 31 and the second photosensitive insulating material sheet 32 are not limited to those described in the above embodiments.

  In the above embodiment, a photomask is used for exposure by the photolithography method, but it is also possible to perform the process using an exposure apparatus that performs exposure without using a photomask.

1 is an external view of a multilayer structure component to which a via hole forming method according to a first embodiment of the present invention is applied. It is arrow AA sectional drawing of FIG. It is process drawing which shows the formation method of a 1st conductor. It is process drawing which shows the 1st thru | or 4th process of the 1st time. It is process drawing which shows the 1st thru | or 4th process of the 2nd time. It is process drawing which shows the formation method of a 2nd conductor. It is sectional drawing which shows the produced multilayer structure. It is process drawing for demonstrating the usage example of this Example. It is an end elevation which shows the 2nd process of the via hole formation method concerning 2nd Example of this invention. It is an end view which shows the main processes of 3rd Example of this invention. It is a table | surface figure which shows an experimental result. It is process drawing which shows the conventional via hole formation method. It is sectional drawing which shows a non-uniform | heterogenous via hole. It is sectional drawing which shows the state which a thick photosensitive insulating material sheet shrinks by sintering. It is sectional drawing which shows an example of the via hole of a high aspect ratio.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... External electrode, 2 ... Support substrate, 3 ... Interconductor insulating layer, 4 ... 1st conductor, 5 ... 2nd conductor, 6 ... Top surface insulating layer, 7 ... Via hole, 8 ... Conductive substance, 22,23 DESCRIPTION OF SYMBOLS ... Photomask, 31 ... 1st photosensitive insulating material sheet, 32 ... 2nd photosensitive insulating material sheet, 33 ... 1st sintered insulating film, 34 ... 2nd sintered insulating film, 71, 71 ' ... 1st via-hole part, 72, 72 '... 2nd via-hole part, 73, 74 ... non-exposure part.

Claims (4)

Multilayer structure component for forming a via hole penetrating an insulating layer having a predetermined thickness and electrically connecting a first conductor laminated with the insulating layer and a second conductor laminated on the insulating layer A via hole forming method,
A first step of forming a green photosensitive insulating material layer thinner than the length of the via hole;
A second step of performing exposure corresponding to the pattern of the via hole portion on the unsintered photosensitive insulating material layer formed in the first step;
A third step of developing the green photosensitive insulating material layer exposed in the second step to form a green via hole portion;
Sintering the photosensitive insulating material layer that has undergone the third step, and forming a thin insulating layer having a via hole portion, and a fourth step,
By repeating the steps from the first step to the fourth step a plurality of times, the insulating layer having the predetermined thickness is formed by the plurality of stacked thin insulating layers, and the plurality of via hole portions communicated with each other. Forming the via hole,
A method of forming a via hole in a multilayer structure component. The method for forming a via hole in a multilayer structure component according to claim 1,
In the second step, exposure corresponding to the pattern of the via hole portion is performed so that the diameter of the via hole portion is equal to or larger than the thickness of the photosensitive insulating material layer.
A method of forming a via hole in a multilayer structure component. In the method for forming a via hole in a multilayer structure component according to claim 1 or 2,
The photosensitive insulating material layer is formed by applying a photosensitive glass paste.
A method of forming a via hole in a multilayer structure component. In the method for forming a via hole in a multilayer structure component according to any one of claims 1 to 3,
When the above-mentioned steps from the first step to the fourth step are repeated a plurality of times, the photosensitive insulating material layer used at any one time is different from the thermal contraction rate of the photosensitive insulating material layer used at other times. Use a photosensitive insulating material layer with thermal shrinkage,
A method for forming a via hole in a multilayer structure component.

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