JP2016017882A - Substrate with function of measuring film thickness and method for measuring thickness of insulating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for measuring the thickness of an insulating layer that can make a measurement in easy and non-destructive manners.SOLUTION: The method for measuring the thickness of an insulating layer includes the steps of: preparing a substrate 1 provided with an antenna PA having a first metal layer 21, a first insulating layer 41 on the first metal layer 21, and a second metal layer 22 on the first insulating layer 41 facing the metal layer 21; forming a second insulating layer 42 with a thickness to be measured on the second metal layer 22; and calculating the thickness of the second insulating layer 42 based on a measured resonance frequency of the antenna PA.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a substrate with a film thickness measuring function and a method for measuring a film thickness of an insulating layer.

  Conventionally, there are wiring boards on which electronic components such as semiconductor chips are mounted. In such a wiring board, the design specification of the film thickness of the interlayer insulating layer is determined, and it is necessary to measure and check the film thickness of the interlayer insulating layer in the manufacturing process.

JP-A-62-22003 JP 2001-267804 A JP 2010-73741 A JP 2012-4328 A

  As described in the preliminary item section below, the method of measuring the thickness of the insulating resin layer of the wiring board with a three-dimensional length measurement system depends on the diameter of the via hole, the resin material, and the process conditions. Tends to be cumbersome.

  Further, when measuring the thickness of the OSP film of the thin film of the wiring board by the elution method, it is necessary to separate the analysis part of the wiring board, and there is a problem that takes time.

  It is an object of the present invention to provide a substrate with a film thickness measuring function capable of measuring the thickness of an insulating layer in a simple manner and non-destructively, and a method for measuring the thickness of an insulating layer.

  According to one aspect of the following disclosure, a base insulating layer in which a film thickness measurement region and a wiring formation region are defined, and a first metal for an antenna formed on the base insulating layer in the film thickness measurement region A first wiring layer formed on the base insulating layer in the wiring forming region; a first insulating layer formed on the base insulating layer, the first metal layer, and the first wiring layer; A second metal layer for the antenna formed on the first insulating layer in the film thickness measurement region so as to face the first metal layer, and the first insulation in the film thickness measurement region. A first electrode pad formed on the layer and connected to the first metal layer via a first via conductor disposed on the first insulating layer; and on the first insulating layer in the wiring formation region. A second wiring layer formed on the second metal layer and covering the second metal layer, and a second insulating layer to be measured for film thickness The first metal layer and the first wiring layer are formed from the same layer and are electrically insulated, and the second metal layer and the second wiring layer are the same. There is provided a substrate with a film thickness measuring function which is formed from one layer and is electrically insulated.

  According to another aspect of the disclosure, the first insulating layer is formed so as to face the first metal layer, the first insulating layer formed on the first metal layer, and the first metal layer. A step of preparing a substrate including an antenna including a second metal layer formed on the layer, a step of forming a second insulating layer to be a film thickness measurement target on the second metal layer, An insulating layer thickness measurement method is provided that includes a step of calculating the thickness of the second insulating layer based on measuring the resonance frequency of the antenna.

  According to the following disclosure, a substrate with a film thickness measurement function includes an antenna having a structure in which a first insulating layer is sandwiched between a first metal layer and a second metal layer in a film thickness measurement region. Then, a second insulating layer to be measured for film thickness is formed on the antenna.

  The film thickness of the second insulating layer can be calculated based on measuring the resonance frequency of the antenna. In this manner, the thickness of the insulating layer can be measured by a simple method and nondestructively without depending on the diameter of the via hole, the resin material, and the process conditions.

1A to 1C are cross-sectional views illustrating a method for measuring the thickness of an insulating layer according to preliminary matters. 2A and 2B are a cross-sectional view and a plan view showing the OSP film thickness measuring method according to the preliminary matter. 3A to 3D are cross-sectional views (part 1) illustrating the method for manufacturing the substrate with a film thickness measuring function according to the first embodiment. 4A and 4B are a cross-sectional view and a plan view (part 2) illustrating the method for manufacturing the substrate with a film thickness measuring function according to the first embodiment. 5A to 5D are cross-sectional views (part 3) illustrating the method for manufacturing the substrate with a film thickness measuring function according to the first embodiment. FIG. 6 is a sectional view (No. 4) showing the method for manufacturing the substrate with a film thickness measuring function of the first embodiment. FIG. 7 is a cross-sectional view and a plan view showing the substrate with a film thickness measuring function of the first embodiment. 8 is a cross-sectional view taken along the line II-II of the plan view of FIG. 9 is a cross-sectional view and a plan view showing a method for measuring the film thickness of the insulating layer using the substrate with a film thickness measuring function of FIG. 10 is a cross-sectional view taken along the line II-II of the plan view of FIG. FIG. 11 is a graph showing the relationship between the thickness of the polyimide layer and the resonance frequency of the patch antenna. FIG. 12 is a cross-sectional view and a plan view showing a substrate with a film thickness measuring function according to the second embodiment. 13 is a cross-sectional view taken along the line II-II of the plan view of FIG. FIG. 14 is a cross-sectional view and a plan view showing a method for measuring the thickness of the OSP film using the substrate with a film thickness measuring function of FIG.

  Hereinafter, embodiments will be described with reference to the accompanying drawings.

  Prior to describing the embodiment, preliminary items that serve as a basis will be described. 1A to 1C show a method for measuring the thickness of an insulating resin layer of a wiring board according to preliminary matters.

  As shown in FIG. 1A, after forming a wiring layer 200 made of copper on the first insulating resin layer 100, a second insulating resin layer 120 that covers the wiring layer 200 is formed. Next, as shown in FIG. 1B, the second insulating resin layer 120 is processed by a laser to form a via hole VH that reaches the wiring layer 200.

  Thereafter, by performing a desmear process, the resin smear in the via hole VH is removed and cleaned.

  Here, it is necessary to check whether the film thickness of the second insulating resin layer 120 is within the design specification range.

  As shown in FIG. 1C, the structure in which the wiring layer 200 is exposed at the bottom of the via hole VH formed in the second insulating resin layer 120 is irradiated with light by a three-dimensional length measurement system. At this time, the difference between the focal length D1 of the surface of the wiring layer 200 at the bottom of the via hole VH and the focal length D2 of the surface of the second insulating resin layer 120 is the film thickness of the second insulating resin layer 120 on the wiring layer 200. Measured.

  In this measurement method, when the diameter of the via hole VH is reduced to about 20 μm to 10 μm, or when the thickness of the second insulating resin layer 120 is considerably increased, the wiring layer 200 at the bottom of the via hole VH cannot be recognized. , Film thickness measurement becomes impossible.

  Also, the image contrast differs between the surface of the second insulating resin layer 120 and the surface of the wiring layer 200 (copper) at the bottom of the via hole VH. For this reason, in order to detect each surface reliably, it is necessary to adjust the light quantity of illumination etc., and a measurement operation becomes complicated.

  Furthermore, when the resin material of the second insulating resin layer 120 and the process conditions in each process are changed, the surface states of the second insulating resin layer 120 and the wiring layer 200 at the bottom of the via hole VH change each time. . For this reason, it is necessary to adjust measurement conditions according to the change of each surface state, and a measurement operation becomes complicated.

  Next, a method for measuring the thickness of the OSP (Organic Solderability Preservative) film of the wiring board according to the preliminary matter will be described. As shown in FIG. 2A, in the wiring substrate 600, connection pads P made of copper are formed on the insulating resin layer 300. Further, a solder resist layer 400 having an opening 420 provided on the connection pad P is formed on the insulating resin layer 300.

  Further, a thin OSP film 500 having a thickness of about 100 nm is formed on the surface of the connection pad P in the opening 420 of the solder resist layer 400. The OSP film 500 is an organic protective film for preventing oxidation of the surface of the connection pad P (copper).

  As a method for measuring the thickness of the OSP film 500 in FIG. In the elution method, as shown in FIG. 2B, the analysis portion 600a on which the OSP film 500 of the wiring substrate 600 is formed is punched out by pressing or the like to obtain the individual sample S.

  And the average film thickness of the OSP film | membrane 500 adhering to the piece sample S is estimated by melt | dissolving the piece sample S with a solvent and measuring the component amount of the analysis object eluted in it.

  As described above, when the thickness measurement of the OSP film 500 is performed by the elution method, the sample size is limited, and the analysis portion 600a of the wiring board 600 needs to be the individual sample S. is there.

  The method for measuring the film thickness of the insulating layer using the substrate with a film thickness measurement function of the embodiment described below can solve the above-described problems.

(First embodiment)
3 to 6 are diagrams illustrating a method for manufacturing a substrate with a film thickness measuring function according to the first embodiment, and FIG. 7 is a diagram illustrating the substrate with a film thickness measuring function according to the first embodiment.

  In the present embodiment, a method for measuring a film thickness of an insulating layer will be described while explaining a method for manufacturing a substrate with a film thickness measurement function.

  First, a method for forming a patch antenna for measuring the thickness of an insulating layer on a wiring board will be described. As shown in FIG. 3A, first, a base insulating layer 10 of a wiring board is prepared.

  The base insulating layer 10 may be a core substrate such as a glass epoxy resin, or may be an interlayer insulating layer made of a resin in the process of manufacturing a build-up wiring layer formed on the core substrate. Alternatively, the base insulating layer 10 of the wiring board may be an interlayer insulating layer that functions as a board of a coreless wiring board that does not have a core board.

  In the base insulating layer 10 of the wiring board, a film thickness measurement region A in which a patch antenna for film thickness measurement is disposed and a wiring formation region B in which an electrical wiring layer is disposed are defined.

  Although not particularly illustrated, the wiring board is a large-sized substrate for multi-sided drawing, and has a plurality of product areas and dicing areas provided in a lattice shape so as to surround each product area.

  The film thickness measurement region A described above is disposed in an arbitrary region of the dicing region, or is disposed at one end in each product region. Further, the wiring formation region B is arranged in each product region.

  Next, as shown in FIG. 3B, the first metal layer 21 is formed on the base insulating layer 10 in the film thickness measurement region A. The first metal layer 21 disposed in the film thickness measurement region A is formed as a collective pattern ground plane layer. The first metal layer 21 is formed in a quadrangular shape, for example.

  At the same time, the first wiring layer 31 is formed on the base insulating layer 10 in the wiring formation region B. The first wiring layer 31 and the first metal layer 21 are formed electrically independently.

  When the base insulating layer 10 is a core substrate, a through conductor is formed in the core substrate, and the first wiring layers 31 on both sides are interconnected via the through conductor. In the case of having a core substrate, a multilayer wiring layer may be formed on both sides.

  Alternatively, when the base insulating layer 10 is formed as an interlayer insulating layer, and the lower wiring layer is formed thereunder, the first wiring layer 31 is placed on the lower side via via conductors arranged in the base insulating layer 10. Connected to the wiring layer.

  Next, as shown in FIG. 3C, an uncured resin film is applied on the base insulating layer 10, the first metal layer 21, and the first wiring layer 31, and heat-treated to be cured. A one-layer insulating layer 41 is formed. As a resin material of the first interlayer insulating layer 41, an epoxy resin or a polyimide resin is used.

  Thereafter, as shown in FIG. 3D, the first interlayer insulating layer 41 is processed with a laser. Thereby, in the film thickness measurement region A, the first via hole VH1 reaching the one end portion of the first metal layer 21 and the second via hole VH2 reaching the other end portion of the first metal layer 21 are formed. In the wiring formation region B, a third via hole VH3 reaching the connection portion of the first wiring layer 31 is formed.

  Thereafter, a desmear process is performed with a potassium permanganate solution or the like to remove the resin smears in the first, second, and third via holes VH1, VH2, and VH3 and clean them.

  Subsequently, as shown in the cross-sectional view of FIG. 4, one end of the first metal layer 21 is formed on the first interlayer insulating layer 41 in the film thickness measurement region A via the first via conductor VC1 in the first via hole VH1. A first electrode pad P1 connected to the portion is formed.

  At the same time, the second electrode connected to the other end of the first metal layer 21 on the first interlayer insulating layer 41 in the film thickness measurement region A via the second via conductor VC2 in the second via hole VH2. The pad P2 is formed. The film thickness measurement region A in the cross-sectional view of FIG. 4 corresponds to a cross section taken along II in the plan view of FIG. The plan view of FIG. 4 is drawn in perspective.

  At the same time, referring to the plan view of FIG. 4, the second metal layer 22 is formed on the first interlayer insulating layer 41 in the film thickness measurement region A. The second metal layer 22 is formed on the first interlayer insulating layer 41 so as to face the first metal layer 21 (ground plane layer) with the first interlayer insulating layer 41 interposed therebetween. The second metal layer 22 is disposed in the film thickness measurement region A as a collective pattern antenna pattern layer.

  The second metal layer 22 has an extending portion 22a extending toward the first and second electrode pads P1 and P2, and includes a pad portion PX on the tip side.

  At the same time, as shown in the cross-sectional view of FIG. 4, the first wiring layer 31 is connected to the first interlayer insulating layer 41 in the wiring formation region B via the third via conductor VC3 in the third via hole VH3. A second wiring layer 32 is formed. The second wiring layer 32 and the second metal layer 22 are formed electrically independently.

  As described above, a patch antenna PA having a capacitor structure in which the first interlayer insulating layer 41 is sandwiched between the first metal layer 21 and the second metal layer 22 in the film thickness measurement region A is constructed. The patch antenna PA is formed electrically independently from the first wiring layer 31 and the second wiring layer 32 formed in the wiring formation region B.

As will be described later, an interlayer insulating layer to be measured for film thickness is formed on the patch antenna PA, and the film thickness of the interlayer insulating layer can be calculated by measuring the resonance frequency of the patch antenna PA. The first and second electrode pads P1, P2, the second metal layer 22, and the second wiring layer 32 are formed by a semi-additive method. This will be described in detail with reference to FIGS. 5A to 5D, the wiring formation region B is partially shown from the second via hole VH2 in the film thickness measurement region A of FIG. 3D described above.

  As shown in FIG. 5A, electroless plating or sputtering is performed on the first interlayer insulating layer 41 in FIG. 3D and in the first, second, and third via holes VH1, VH2, and VH3. Then, a seed layer 12 made of copper or the like is formed.

  Subsequently, as shown in FIG. 5B, a plating resist in which an opening 13a is provided in a region where the first and second electrode pads P1, P2, the second metal layer 22 and the second wiring layer 32 are disposed. Layer 13 is formed on seed layer 12.

  Next, as shown in FIG. 5C, a metal plating layer 14 made of copper or the like is formed in the opening 13a of the plating resist layer 13 by electrolytic plating using the seed layer 12 as a plating power feeding path.

  Further, as shown in FIG. 5D, after the plating resist layer 13 is removed, the seed layer 12 is etched using the metal plating layer 14 as a mask. In this manner, the first and second electrode pads P1, P2, the second metal layer 22, and the second wiring layer 32 shown in FIG. 4 are formed by the seed layer 12 and the metal plating layer 14, respectively.

  The first metal layer 21 and the first wiring layer 31 shown in FIG. 3B are also formed by a similar semi-additive method.

  Next, as shown in FIG. 6, the second target for film thickness measurement is formed on the first interlayer insulating layer 41, the first and second electrode pads P <b> 1 and P <b> 2, the second metal layer 22, and the second wiring layer 32. An interlayer insulating layer 42 is formed.

  The second interlayer insulating layer 42 is formed by a method similar to the method for forming the first interlayer insulating layer 41 of FIG. Similarly, the second interlayer insulating layer 42 is formed of an epoxy resin or a polyimide resin.

  Subsequently, as shown in the cross-sectional view of FIG. 7, in the film thickness measurement region A, the second interlayer insulation of the portion of the first electrode pad P <b> 1, the second electrode pad P <b> 2, and the pad portion PX of the second metal layer 22. Layer 42 is processed with a laser. The film thickness measurement region A in the cross-sectional view of FIG. 7 corresponds to a cross section taken along II in the plan view of FIG. The plan view of FIG. 7 is drawn in perspective.

  Accordingly, referring to FIG. 7 in addition to the plan view, the first electrode pad P1, the second electrode pad P2, and the pad portion PX of the second metal layer 22 are collectively exposed in the second interlayer insulating layer. Part 42a is formed. The region other than the pad portion PX of the second metal layer 22 is covered with the second interlayer insulating layer 42 to be measured for film thickness.

  At the same time, as shown in the cross-sectional view of FIG. 7, in the wiring formation region B, a fourth via hole VH4 reaching the second wiring layer 32 is formed in the second interlayer insulating layer 42 by laser processing. Alternatively, the fourth via hole VH4 may be formed in the wiring formation region B after the film thickness measurement described later is completed.

  As described above, the substrate 1 with a film thickness measuring function of the embodiment is obtained.

  As shown in the sectional view and the plan view of FIG. 7, the first metal layer 21 for the patch antenna is formed on the base insulating layer 10 in the film thickness measurement region A of the substrate 1 with film thickness measurement function of the embodiment. ing. The first metal layer 21 is formed as a ground plane layer.

  A first interlayer insulating layer 41 is formed on the first metal layer 21. Further, a second metal layer 22 for a patch antenna is formed on the first interlayer insulating layer 41 so as to face the first metal layer 21. The second metal layer 22 is formed as an antenna pattern layer.

  A first electrode pad P1 connected to one end of the first metal layer 21 through a first via conductor VC1 disposed in the first interlayer insulating layer 41 is formed on the first interlayer insulating layer 41. Yes. On the first interlayer insulating layer 41, a second electrode pad P2 connected to the other end of the first metal layer 21 via a second via conductor VC2 disposed in the first interlayer insulating layer 41 is provided. Is formed.

  The second metal layer 22 has an extending portion 22a extending toward the first and second electrode pads P1 and P2, and includes a pad portion PX on the tip side. The pad portion PX of the second metal layer 22 is arranged in the region between the first electrode pad P1 and the second electrode pad P2 so as to be aligned in the lateral direction.

  8 is a cross-sectional view taken along the line II-II of the plan view of FIG. As shown in the plan view of FIG. 7 and FIG. 8, the second interlayer insulating layer 42 to be subjected to film thickness measurement is formed so as to cover the entire portion of the second metal layer 22 except the pad portion PX.

  As shown in the cross-sectional view and the plan view of FIG. 7, the second interlayer insulating layer 42 to be subjected to film thickness measurement includes the first electrode pad P <b> 1, the second electrode pad P <b> 2, and the pad portion PX of the second metal layer 22. Is provided with a collective opening 42a for exposing the. Alternatively, the openings may be divided and arranged individually on the first electrode pads P1, the second electrode pads P2, and the pad portions PX of the second metal layer 22.

  In this manner, the patch antenna PA having a capacitor structure in which the first interlayer insulating layer 41 is sandwiched between the first metal layer 21 and the second metal layer 22 is constructed in the film thickness measurement region A. As will be described later, the patch antenna PA has a film thickness measurement function.

  The patch antenna PA is formed electrically independently from the first wiring layer 31 and the second wiring layer 32 formed in the wiring formation region B.

  Similarly, as shown in the sectional view of FIG. 7, the first wiring layer 31 is formed on the base insulating layer 10 in the wiring forming region B of the substrate 1 with a film thickness measuring function. A first interlayer insulating layer 41 is formed on the base insulating layer 10 and the first wiring layer 31. On the first interlayer insulating layer 41, a second wiring layer 32 connected to the first wiring layer 31 through a third via conductor VC3 disposed in the first interlayer insulating layer 41 is formed.

  A second interlayer insulating layer 42 is formed on the first interlayer insulating layer 41. In the second interlayer insulating layer 42, a fourth via hole VH4 reaching the second wiring layer 32 is formed. At this time, the fourth via hole VH4 is not necessarily formed.

  The first metal layer 21 in the film thickness measurement region A and the first wiring layer 31 in the wiring formation region B are formed from the same layer and are electrically insulated. Similarly, the second metal layer 22 in the film thickness measurement region A and the second wiring layer 32 in the wiring formation region B are formed from the same layer and are electrically insulated.

  Next, a method for measuring the thickness of the second interlayer insulating layer 42 will be described with reference to FIGS. The cross-sectional view of FIG. 9 corresponds to a cross section taken along II in the plan view of FIG. The plan view of FIG. 9 is drawn in perspective. FIG. 10 is a cross-sectional view taken along the line II-II of the plan view of FIG.

  As shown in the sectional view and plan view of FIG. 9, a GSG (ground / signal / ground) probe (not shown) having one signal pin S and two ground pins G is prepared.

  Then, the signal pin S of the GSG probe is brought into contact with and connected to the pad portion PX of the second metal layer 22 of the patch antenna PA. At the same time, the ground pin G of the GSG probe is connected to and connected to the first electrode pad P1 and the second electrode pad P2 of the patch antenna PA.

  Thereby, the signal pin S of the GSG probe is electrically connected to the second metal layer 22 connected to the pad portion PX. The two ground pins G of the GSG probe are electrically connected to the lower first metal layer 21 via the first and second electrode pads P1 and P2 and the first and second via conductors VC1 and VC2, respectively. The

  Then, the resonance frequency of the patch antenna PA is measured using a network analyzer (not shown) connected to the GSG probe. The resonance frequency is a frequency at which the high frequency current becomes maximum when a high frequency is applied to the patch antenna PA and the frequency of the high frequency is gradually changed.

  When the film thickness of the second interlayer insulating layer 42 formed on the patch antenna PA changes, the resonance frequency of the patch antenna PA changes.

  Using this characteristic, the relationship between the film thickness of the second interlayer insulating layer 42 and the resonance frequency of the patch antenna PA is created in advance as a calibration curve. Then, by measuring the resonance frequency of the patch antenna PA of the measurement sample, the thickness of the second interlayer insulating layer 42 can be calculated from the calibration curve data.

  As shown in FIG. 10, the electric field generated at the end of the patch antenna PA passes through the second interlayer insulating layer 42, the first interlayer insulating layer 41, and the base insulating layer 10 from the upper surface of the second metal layer 22, and One metal layer 21 faces the lower surface.

  Thereby, compared with the case where the second interlayer insulating layer 42 does not exist, the capacitance of the capacitor constructed by the patch antenna PA is substantially changed, so that it is estimated that the resonance frequency of the patch antenna PA changes based on the capacitance. The

  The inventor of the present application creates five experimental samples in which the film thickness of the second interlayer insulating layer 42 on the patch antenna PA is changed by the film thickness measurement method described above with reference to FIG. The frequency was measured. A polyimide layer was used as an insulating layer to be measured for film thickness, and the film thickness was set to 0 μm, 63 μm, 126 μm, 189 μm, and 252 μm.

  Further, the area of the square region excluding the extending portion 22a of the second metal layer 22 of the patch antenna PA was set to about 1 mm × 1 mm.

  FIG. 11 shows the experimental results, and the relationship between the film thickness of the polyimide layer and the resonance frequency of the patch antenna is graphed. As shown in FIG. 11, when the thickness of the polyimide layer is 0 μm, the resonance frequency is 65.91 GHz, when the film thickness is 63 μm, the resonance frequency decreases to 63.32 GHz, and when the film thickness is 126 μm, the resonance frequency. Fell further to 62.57 GHz.

  Thus, when the film thickness of the polyimide layer is in the range from 0 μm to 126 μm, the resonance frequency becomes lower as the film thickness becomes thinner.

  On the other hand, even if the thickness of the polyimide layer is further increased to 189 μm, the resonance frequency hardly changes at 62.55 GHz, and even when the thickness of the polyimide layer is increased to 252 μm, the resonance frequency hardly changes at 62.53 GHz. It was.

  Thus, it was found that the resonance frequency did not change when the thickness of the polyimide layer exceeded 126 μm. In the description with reference to FIG. 10 described above, when the film thickness of the polyimide layer is increased to some extent, the electric field generated on the upper side from the second metal layer 22 reaches only halfway through the film of the polyimide layer. It is presumed to be.

  In the patch antenna PA of the experimental sample described above, if the polyimide layer has a thickness of 126 μm or less, the film thickness can be calculated by measuring the resonance frequency of the patch antenna PA. Since the film thickness of the interlayer insulating layer used in the wiring board is 10 μm to 100 μm, for example, about 30 μm, the film thickness can be measured by the method described above.

  In this way, as shown in FIG. 11, the relationship between the thickness of the insulating layer to be measured and the resonance frequency of the patch antenna is prepared in advance as a calibration curve. Then, by measuring the resonance frequency of the patch antenna of the measurement sample, the film thickness of the insulating layer can be calculated from the calibration curve data.

  For example, in a measurement sample of a certain product, when the resonance frequency of the patch antenna PA is 64.50 GHz, the thickness of the polyimide layer on the patch antenna PA is about 30 μm from the calibration curve of FIG. Calculated.

  It is also possible to display the film thickness simultaneously with the measurement of the resonance frequency by systematizing the calibration curve data as shown in FIG. 11 and linking it with the measurement value of the resonance frequency of the patch antenna PA.

  Note that the resonance frequency can be changed by changing the design of the second metal layer 22 (antenna pattern layer) of the patch antenna PA. For the measurement of the thickness of various insulating layers, the second metal layer 22 (antenna pattern layer) may be designed so that the resonance frequency changes according to the change in thickness.

  As described above, in this embodiment, the film thickness of the interlayer insulating layer can be obtained by measuring the resonance frequency of the patch antenna. For this reason, unlike the case of using a three-dimensional length measurement system, even if the resin material of the interlayer insulating layer and the process conditions of each process are changed, it is not necessary to adjust the measurement conditions each time, and the film can be formed by a simple method. Thickness measurement can be performed.

  Further, since no via hole is required when measuring the film thickness, there is no problem that the film thickness cannot be measured even when the diameter of the via hole is reduced.

  Further, unlike the case where the elution method is used, the film thickness can be measured in a non-destructive and short manner without taking individual samples from the wiring board for film thickness measurement.

  After the film thickness measurement of the second interlayer insulating layer 42 in FIG. 7 is performed by the above method, a desired multilayer wiring layer is formed on the second interlayer insulating layer 42 in the wiring formation region B. By forming the patch antenna under the interlayer insulating layer to be measured for the thickness of the multilayer wiring layer, the thickness of the interlayer insulating layer can be similarly measured.

(Second Embodiment)
In the second embodiment, a method for measuring the thickness of an OSP film as another insulating layer will be described. 12 to 14 are diagrams for explaining a method of measuring the thickness of the OSP film.

  A film thickness measurement region A in the cross-sectional view of FIG. 12 corresponds to a cross section taken along II in the plan view of FIG. The plan view of FIG. 12 is drawn in perspective. FIG. 13 is a cross-sectional view taken along the line II-II of the plan view of FIG.

  As shown in the cross-sectional view and the plan view of FIG. 12, when measuring the thickness of the OSP film, the second wiring layer 32 is formed as the connection pad P in the wiring formation region B in the process of FIG. . The connection pad P is formed as the uppermost wiring layer of the multilayer wiring layer and may be arranged in an island shape or may be arranged at one end of the lead-out wiring. An electronic component such as a semiconductor element is connected to the connection pad P.

  Then, a solder resist layer 44 is formed on the first interlayer insulating layer 41. In the wiring formation region B, the first opening 44 a of the solder resist layer 44 is disposed on the connection pad P. In the film thickness measurement region A, the second openings 44b of the solder resist layer 44 are collectively disposed on the second metal layer 22, the first and second electrode pads P1, P2.

  Further, a thin OSP film 46 is formed on the surface of the connection pad P in the opening 44a of the solder resist layer 44 in the wiring formation region B by chemical treatment. At the same time, in the film thickness measurement region A, the OSP film 46 having the same thickness is also formed on the second metal layer 22 and the first and second electrode pads P1 and P2 in the opening 44b of the solder resist layer 44. An OSP film 46 is formed in the hatched area in the plan view of FIG.

  In this way, as shown in the cross-sectional views of FIGS. 12 and 13, the OSP that is the target of film thickness measurement on the first and first electrode pads P 1 and P 2 and the second metal layer 22 in the film thickness measurement region A. A film 46 is formed. Thereby, the board | substrate 1a with a film thickness measurement function of 2nd Embodiment is obtained.

  Next, as shown in FIG. 14, the signal pin S of the GSG probe is connected to and connected to the pad portion PX of the second metal layer 22 of the patch antenna PA, as in FIG. 9 described above. At the same time, the two ground pins G of the GSG probe are connected to the first and second electrode pads P1 and P2 of the patch antenna PA.

  At this time, the OSP film 46 is formed on the surface of the pad portion PX of the second metal layer 22 and the first and second electrode pads P1 and P2. However, the GSG probe can be electrically connected to the first and second electrode pads P1, P2 and the pad portion PX by pushing and breaking through the OSP film 46 with the signal pin S and the ground pin G of the GSG probe.

  Similarly, the resonance frequency of the patch antenna PA covered with the OSP film 46 is measured. Similar to the first embodiment described above, the relationship between the thickness of the OSP film 46 and the resonance frequency of the patch antenna PA is created in advance as a calibration curve, so that the OSP can be obtained from the measured resonance frequency and calibration curve data. The film thickness of the film 46 can be calculated. The second embodiment has the same effects as the first embodiment.

  In the first and second embodiments described above, the measurement of the film thickness of the resin layer and the OSP film is exemplified, but the film thickness of various organic or inorganic insulating layers can be measured. Examples of the inorganic insulating layer include a silicon oxide layer, a silicon nitride layer, and a silicon oxynitride layer.

DESCRIPTION OF SYMBOLS 1,1a ... Board | substrate with a film thickness measurement function, 10 ... Underlayer insulation layer, 12 ... Seed layer, 13 ... Plating resist layer, 13a, 42a ... Opening part, 14 ... Metal plating layer, 21 ... 1st metal layer, 22 ... 2nd metal layer, 31 ... 1st wiring layer, 32 ... 2nd wiring layer, 41 ... 1st interlayer insulation layer, 42 ... 2nd interlayer insulation layer, 44 ... Solder resist layer, 44a ... 1st opening part, 44b ... 2nd opening, 46 ... OSP film, A ... film thickness measurement region, B ... wiring formation region, G ... ground pin, PA ... patch antenna, P1 ... first electrode pad, P2 ... second electrode pad, PX ... pad Part, S ... signal pin, VC1 ... first via conductor, VC2 ... second via conductor, VC3 ... third via conductor, VH1 ... first via hole, VH2 ... second via hole, VH3 ... third via hole, VH4 ... fourth Beer hall.

Claims (8)

A base insulating layer in which a film thickness measurement region and a wiring formation region are defined;
A first metal layer for an antenna formed on the base insulating layer in the film thickness measurement region;
A first wiring layer formed on the base insulating layer in the wiring formation region;
A first insulating layer formed on the base insulating layer, the first metal layer, and the first wiring layer;
A second metal layer for the antenna formed on the first insulating layer in the film thickness measurement region so as to face the first metal layer;
A first electrode pad formed on the first insulating layer in the film thickness measurement region and connected to the first metal layer via a first via conductor disposed in the first insulating layer;
A second wiring layer formed on the first insulating layer in the wiring formation region;
A second insulating layer that is formed to cover the second metal layer and is a film thickness measurement target;
The first metal layer and the first wiring layer are formed from the same layer and are electrically insulated,
The substrate with a film thickness measuring function, wherein the second metal layer and the second wiring layer are formed of the same layer and are electrically insulated.   A second electrode pad formed on the first insulating layer in the film thickness measurement region and connected to the first metal layer via a second via conductor disposed in the first insulating layer; The board | substrate with a film thickness measurement function of Claim 1 characterized by the above-mentioned. The second metal layer includes a pad portion;
3. The film thickness measurement according to claim 2, wherein the second insulating layer includes an opening that exposes a pad portion of the first electrode pad, the second electrode pad, and the second metal layer. Functional board.   4. The substrate with a film thickness measuring function according to claim 1, wherein the second insulating layer is a resin layer or an OSP film. 5. A first metal layer;
A first insulating layer formed on the first metal layer;
Preparing a substrate including an antenna including a second metal layer formed on the first insulating layer so as to face the first metal layer;
Forming a second insulating layer to be a film thickness measurement target on the second metal layer;
And a step of calculating a film thickness of the second insulating layer based on measuring a resonance frequency of the antenna. In the process of preparing the substrate including the antenna,
The antenna is
A first electrode pad formed on the first insulating layer and connected to the first metal layer via a first via conductor disposed in the first insulating layer;
A second electrode pad formed on the first insulating layer and connected to the first metal layer via a second via conductor disposed in the first insulating layer;
A pad portion provided in the second metal layer,
After the step of forming the second insulating layer,
Forming an opening in the second insulating layer to expose the pad portion of the first electrode pad, the second electrode pad, and the second metal layer;
The resonance frequency is measured based on connecting a ground pin of a probe to the first electrode pad and the second electrode pad, respectively, and connecting a signal pin of the probe to a pad portion of the second metal layer. The method for measuring a film thickness of an insulating layer according to claim 5.   The relationship between the film thickness of the second insulating layer and the resonance frequency of the antenna is prepared in advance as a calibration curve, and the film thickness is calculated by the calibration curve from the measured resonance frequency. The method for measuring a film thickness of the insulating layer according to 5 or 6.   The method for measuring a film thickness of an insulating layer according to claim 5, wherein the second insulating layer is a resin layer or an OSP film.

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