Semiconductor device and method of manufacturing the same

Abstract

The invention provides a semiconductor device and a manufacturing method thereof. The semiconductor device comprises: a substrate (1); the through hole (4) penetrates through the substrate in the thickness direction; a first polymer layer (2) at least continuously covering the inner wall of the through hole (4); a first conductor layer (3) at least continuously covering an inner wall of the first polymer layer (2); and the first electrode (6) is formed on the first surface of the substrate, and the first electrode is electrically connected with the first conductor layer (3).

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor technology, and in particular relates to a semiconductor device and a manufacturing method thereof. Background Art

[0002] In 2.5D and 3D packaging processes, a layer of silicon dioxide is usually deposited in the through-hole as an insulating layer. However, as the through-hole aspect ratio continues to increase, the effect of PECVD (plasma enhanced chemical vapor deposition) depositing silicon dioxide will also deteriorate, which is manifested in poor uniformity of the through-hole sidewall film thickness, poor coverage of the through-hole sidewall and the chip surface, and poor adhesion of the through-hole bottom sidewall. If the thickness of the deposited silicon dioxide film is too thick, the film will crack due to stress problems, and if the thickness of the deposited silicon dioxide film is too thin, it will cause leakage on the bottom sidewall of the through-hole; although the use of PE-ALD (plasma enhanced atomic layer deposition) to deposit silicon dioxide can ensure the coverage of the chip surface and the through-hole sidewall, the cost of a single chip is relatively high.

[0003] In addition, whether PECVD or PE-ALD is used to deposit silicon dioxide films, a process temperature greater than 400°C must be used to grow a high-quality film layer. However, high temperatures greater than 400°C will cause some chip functions, structures or previous process packaging structures to be damaged. For example, the CTE (coefficient of thermal expansion) of adjacent hierarchical structural materials in the previous layer is very different, which will cause faults at high temperatures and cause functional failures, resulting in a decrease in the yield of the prepared integrated circuits and increased costs.

[0004] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention

[0005] In order to solve the above-mentioned problems or at least similar problems, the present application provides a semiconductor device and a method for manufacturing the same. In the semiconductor device, the side walls of the through hole are covered with a polymer, which can improve the coverage, play a good buffering and barrier role, and improve the reliability of the semiconductor device. In addition, high-temperature treatment is avoided during the setting of the polymer, thereby improving the yield of the product and reducing costs.

[0006] An embodiment of the present application provides a semiconductor device, the semiconductor device comprising:

[0007] Substrate 1;

[0008] A through hole 4, which penetrates the substrate in the thickness direction;

[0009] A first polymer layer 2, which continuously covers at least the inner wall of the through hole 4;

[0010] A first conductor layer 3, which continuously covers at least the inner wall of the first polymer layer 2; and

[0011] The first electrode 6 is formed on the first surface of the substrate, and the first electrode is electrically connected to the first conductor layer 3 .

[0012] In at least one embodiment, the first polymer layer 2 also covers at least a portion of the second surface of the substrate.

[0013] In at least one embodiment, the first conductor layer 3 also at least partially covers the surface of the first polymer layer 2 located on the second surface.

[0014] In at least one embodiment, the semiconductor device further includes:

[0015] A second polymer layer 7 covers at least a portion of the first surface of the substrate.

[0016] In at least one embodiment, the semiconductor device further includes:

[0017] The second conductor layer 9 is located on the surface of the second polymer layer 7 , and the second conductor layer 9 is electrically connected to the first electrode 6 .

[0018] An embodiment of the present application provides a method for manufacturing a semiconductor device, the method comprising:

[0019] At least a first electrode 6 is formed on a first surface of the substrate 1;

[0020] Apply bonding glue 10 on one side of the first surface of the substrate, apply photosensitive glue on the surface of the transparent support sheet 11, and bond the substrate and the support sheet through the bonding glue and the photosensitive glue;

[0021] The substrate is etched from the second surface of the substrate to form a through hole 4 penetrating the substrate in the thickness direction, and the first electrode 6 is exposed from the bottom of the through hole 4;

[0022] Filling the through-hole with a polymer dry film;

[0023] Performing window opening treatment on the polymer dry film in the through hole 4 to form a first polymer layer 2 that at least continuously covers the inner wall of the through hole 4, wherein the inner periphery of the first polymer layer 2 has a through window 12, and the first electrode 6 is exposed from the bottom of the through window 12;

[0024] forming a first conductor layer 3 on the inner wall of the through window, which at least continuously covers the inner wall of the first polymer layer 2, and the first conductor layer 3 is in contact with the first electrode 6; and

[0025] The photosensitive adhesive is irradiated with light having a predetermined wavelength through the support sheet to separate the bonding adhesive from the photosensitive adhesive.

[0026] In at least one embodiment, before bonding the substrate and the support sheet, a second polymer layer 7 and a second conductor layer 9 are formed on the first surface of the substrate.

[0027] The second conductor layer 9 is located on the surface of the second polymer layer 7 , and the second conductor layer 9 is electrically connected to the first electrode 6 .

[0028] In at least one embodiment, the polymer dry film also covers at least a portion of the second surface of the substrate.

[0029] In at least one embodiment, the first conductor layer 3 also at least partially covers the surface of the first polymer layer 2 located on the second surface.

[0030] In at least one embodiment, the polymer dry film is filled into the through hole by vacuum lamination.

[0031] The beneficial effects of the present application are as follows: using a polymer to cover the sidewalls of the through hole can improve coverage, play a good buffering and barrier role, improve the reliability of the semiconductor device, and avoid high-temperature treatment during the process of setting the polymer, thereby improving the yield of the product and reducing costs.

[0032] With reference to the following description and accompanying drawings, the specific embodiments of the present application are disclosed in detail, indicating the way in which the principles of the present application can be adopted. It should be understood that the embodiments of the present application are not limited in scope. Within the scope of the spirit and clauses of the appended claims, the embodiments of the present application include many changes, modifications and equivalents.

[0033] Features described and / or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0034] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The included drawings are used to provide a further understanding of the embodiments of the present application, which constitute a part of the specification, are used to illustrate the implementation methods of the present application, and together with the text description, explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0036] Figure 1 is a schematic diagram of a semiconductor device according to Embodiment 1 of the present application;

[0037] Figure 2 is a schematic diagram of a method for manufacturing a semiconductor device according to Embodiment 2 of the present application;

[0038] Figures 3 to 6 It is a schematic cross-sectional diagram of the device corresponding to the main steps of an example of Embodiment 2 of the present application. DETAILED DESCRIPTION

[0039] The method and application of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0040] In each embodiment of the present application, the direction parallel to the surface of the substrate 1 is referred to as the lateral direction, and the direction perpendicular to the surface of the substrate 1 is referred to as the longitudinal direction, or the thickness direction. The first surface of the substrate 1 may be the front surface, and the second surface of the substrate 1 may be the back surface.

[0041] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0042] Example 1

[0043] Embodiment 1 of the present application provides a semiconductor device.

[0044] Figure 1 is a schematic diagram of a semiconductor device according to an embodiment of the present application. Figure 1 As shown, the semiconductor device 100 at least includes: a substrate 1 , a through hole 4 , a first conductor layer 3 , a first polymer layer 2 and a first electrode 6 .

[0045] In this embodiment, the substrate 1 can be a substrate commonly used in the semiconductor manufacturing field, such as a silicon wafer, a silicon-on-insulator (SOI) wafer, a silicon-germanium wafer, a germanium wafer or a gallium nitride (GaN) wafer, etc., or it can be a glass substrate, a sapphire substrate, etc. This embodiment is not limited to the above examples.

[0046] like Figure 1 As shown, the through hole 4 may penetrate the substrate 1 in the thickness direction, for example, the through hole 4 is a through silicon via (TSV). The depth of the through hole 4 is, for example, greater than 50 um or other values.

[0047] The first polymer layer 2 at least continuously covers the inner wall of the through hole 4, thereby achieving good insulation properties at the side wall of the through hole 4. In addition, the first polymer layer 2 may also cover at least a portion of the back side (ie, the second surface) of the substrate 1.

[0048] The first conductor layer 3 at least continuously covers the inner wall of the first polymer layer 2. In addition, the first conductor layer 3 also at least partially covers the surface of the first polymer layer 2 located on the second surface.

[0049] The first electrode 6 is formed on the front side (ie, the first surface) of the substrate 1 , and the first electrode 6 is in contact with the first conductor layer 3 covering the inner wall of the first polymer layer 2 , thereby achieving electrical connection.

[0050] like Figure 1 As shown, the semiconductor device 100 further includes: a second polymer layer 7 and a second conductor layer 9. The second polymer layer 7 covers the first surface (ie, the front surface) of the substrate 1. The second conductor layer 9 is located on the surface of the second polymer layer 7, and the second conductor layer 9 is electrically connected to the first electrode 6.

[0051] The first conductor layer 3 , the first electrode 6 , and the second conductor layer 9 may be made of the same or different conductor materials. For example, the first conductor layer 3 , the first electrode 6 , and the second conductor layer 9 are all made of metal, such as copper or aluminum.

[0052] The first polymer layer 2 and the second polymer layer 7 may be photolithographic polymer materials. In addition, the first polymer layer 2 and the second polymer layer 7 may be the same material or different materials.

[0053] like Figure 1 As shown, adjacent semiconductor devices 100 can be connected to each other, with a front scribing groove 8 and a back scribing groove 5 formed on the substrate 1 between them, and the front scribing groove 8 and the back scribing groove 5 correspond to each other in position, with a deviation of less than 2um. By performing a scribing operation along the front scribing groove 8 and / or the back scribing groove 5, the adjacent semiconductor devices 100 can be separated.

[0054] In addition, the semiconductor device 100 may also have other structures, such as: input / output bumps (I / O bumps) or input / output pads (I / O pads) formed on the first surface or the second surface of the substrate 1; and / or, other logic chips, digital chips, micro-electromechanical systems (MEMS) chips or combinations thereof stacked on the semiconductor device 100.

[0055] In the semiconductor device 100 of the present application, the diameter of the window of the polymer layer 2 on the back surface of the substrate 1 can be 5um or more, and the thickness can be 2um to 10um. The subsequent packaging wiring (RDL) thickness, width and density design window are large and the process window is large, and it is not easy to cause polymer film fracture; the first polymer layer 2 on the side wall of the through hole 4 mainly plays a buffering and blocking role. The thickness of the first polymer layer 2 on the side wall of the entire through hole 4 is uniform and dense, and the thickness can be adjusted according to the photolithography design, which has greater flexibility and is not affected by the roughness of the side wall of the through hole 4. The process is simple, the cost is low, and the finished product yield is high; in addition, the portion of the first polymer layer 2 located on the back surface of the substrate 1 can play a supporting, buffering and blocking role.

[0056] Example 2

[0057] Embodiment 2 of the present application provides a method for manufacturing a semiconductor device, which is used to manufacture the semiconductor device 100 described in Embodiment 1.

[0058] Figure 2 FIG. 2 is a schematic diagram of a method for manufacturing a semiconductor device according to Embodiment 2 of the present application. Figure 2 As shown, the manufacturing method includes:

[0059] Operation 201, forming at least a first electrode 6 on a first surface of a substrate 1;

[0060] Operation 202: coating a bonding adhesive 10 on one side of the first surface of the substrate 1, coating a photosensitive adhesive on the surface of the transparent support sheet 11, and bonding the substrate 1 and the support sheet 11 by the bonding adhesive 10 and the photosensitive adhesive;

[0061] Operation 203, etching the substrate 1 from the second surface of the substrate 1 to form a through hole 4 penetrating the substrate 1 in the thickness direction, and the first electrode 6 is exposed from the bottom of the through hole 4;

[0062] Operation 204, filling the polymer dry film into the through hole 4;

[0063] Operation 205, performing window opening processing on the polymer dry film in the through hole 4 to form a first polymer layer 2 that at least continuously covers the inner wall of the through hole 4, wherein the inner periphery of the first polymer layer 2 has a through window 12, and the first electrode 6 is exposed from the bottom of the through window 12;

[0064] Operation 206: forming a first conductor layer 3 on the inner wall of the through window, which at least continuously covers the inner wall of the first polymer layer 2, and the first conductor layer 3 is in contact with the first electrode 6; and

[0065] Operation 207 , using light with a predetermined wavelength to irradiate the photosensitive adhesive through the support sheet to separate the bonding adhesive from the photosensitive adhesive.

[0066] In operation 201 , a second polymer layer 7 and a second conductor layer 9 may also be formed on the first surface of the substrate 1 . The second conductor layer 9 is located on the surface of the second polymer layer 7 , and the second conductor layer 9 is electrically connected to the first electrode 6 .

[0067] In operation 202 , the support sheet 11 may be, for example, glass.

[0068] Before operation 203 , the substrate 1 may be thinned (eg, chemical mechanical polishing) from the second surface (ie, the back surface) so that the substrate 1 reaches a predetermined thickness.

[0069] In operation 203 , a through hole 4 may be formed by dry etching.

[0070] In operation 204 , the polymer dry film may be filled into the through hole by vacuum lamination; in addition, the polymer dry film may also cover at least a portion of the second surface of the substrate 1 .

[0071] In operation 205, the window opening process may be, for example, to define the window opening position of the polymer dry film by photolithography and perform exposure, and after development, the exposed part is retained and the unexposed part is removed by the developer, or the exposed part is removed by the developer and the unexposed part is retained, depending on the characteristics of the polymer dry film.

[0072] In operation 206 , a first conductor layer 3 may be formed by sputtering a metal seed layer and electroplating. The first conductor layer 3 also at least partially covers the surface of the first polymer layer 2 located on the second surface of the substrate 1 .

[0073] Before operation 207 , further processing may be performed, such as forming an I / O bump or an I / O pad on the back side, and then wafer stacking may be performed or other logic chips, digital chips, MEMS chips, or a combination thereof may be stacked thereon.

[0074] In operation 207, the support sheet 11 may be irradiated with light of a single wavelength to separate the bonding adhesive 10 from the photosensitive adhesive, forming a Figure 1 A semiconductor device 100 is shown.

[0075] The manufacturing method of the embodiment of the present application is further explained below with reference to specific examples. Figures 3 to 6 It is a schematic diagram of the device cross-section corresponding to the main steps of this example.

[0076] The manufacturing method of this example includes the following steps:

[0077] S1. Prepare a substrate 1, wherein the substrate 1 includes a first surface and a second surface, wherein the first surface is the front surface and the second surface is the back surface.

[0078] The front structure of the substrate 1 is formed by processing using an existing method, for example, a second polymer layer 7, a second conductor layer 9 ( Figure 3 not shown), front side scribe line 8, input / output bump (I / O bump), etc.

[0079] S2. Figure 3 As shown, a bonding glue 10 is coated on the first surface of the substrate 1, and the bonding glue 10 covers the front side of the substrate 1 and the corresponding front side structure; a photosensitive glue is coated on the surface of a cleaned support sheet 11 (the support sheet is, for example, glass), and the bonding glue and the photosensitive glue must match, and then the first surface of the substrate 1 and the support sheet 11 are aligned and pressed together, wherein the bonding glue and the photosensitive glue match each other means that when the bonding glue and the photosensitive glue are in contact, they can bond to each other, and when light, such as ultraviolet light, is used, the bonding glue and the photosensitive glue bonded together will be debonded and separated from each other. In this embodiment, the bonding glue is selected from BOND 305, and the photosensitive glue is selected from BOND 701.

[0080] In this embodiment, the thickness of the bonding adhesive is set according to the height of the front structure. The thickness of the bonding adhesive needs to be higher than the highest height of the front structure. At the same time, the surface of the bonding adhesive needs to be kept flat.

[0081] S3. Figure 4 As shown, the back side of the laminated substrate 1 is thinned to the required thickness. The thickness of the substrate 1 after thinning is 50um to 500um (i.e., the thickness of the substrate 1, excluding the thickness of the bonding adhesive and the support sheet 11). The specific thickness of the substrate 1 after thinning is determined according to the product design. The conditions that need to be considered in the product design include the final volume, power consumption, process difficulty, etc.

[0082] In step S3, according to the position of the first electrode 6, the window position of the through hole 4 is defined by photolithography, and then the through hole 4 is etched out by dry etching, and the polymer remaining on the side wall of the through hole 4 (for example, polymer CFn will be attached to the side wall during the etching process) is cleaned. In the whole process, it is necessary to ensure that the position of the through hole 4 and the first electrode 6 are relative. If the position offset between the two is too large, leakage may occur or even damage the electrode; wherein, the relative position of the through hole 4 and the first electrode 6 means that the center of the through hole 4 and the center of the first electrode 6 should theoretically coincide.

[0083] In this embodiment, the through hole 4 is above the first electrode 6 , and the first electrode 6 has a certain margin, which is generally greater than or equal to 25% of the diameter of the through hole 4 , and preferably greater than or equal to 30% of the diameter of the through hole 4 .

[0084] At the same time, it is necessary to control the Scalloping (i.e., the roughness of the sidewall of the through hole 4, usually the ratio of the fan length to the depth) and the notching size at the bottom of the through hole 4, wherein the notching is caused by the accumulation of charges at the corners when etching to the bottom of the through hole, resulting in lateral etching, which leads to over-etching of the bottom structure of the through hole. In this embodiment, the smoother the sidewall of the through hole 4, the better, and the specific data of the Scalloping can be determined according to the current machine and process; in addition, when etching to form the through hole 4, it is necessary to control the process parameters to avoid notching.

[0085] S4. Figure 6 As shown, the polymer dry film is filled into the through hole 4 by vacuum lamination. At the same time, a polymer layer is formed on the surface of the back side of the wafer. The thickness of the back polymer layer formed on the back side of the wafer is 2um to 20um. At the same time, it is necessary to ensure the uniformity of the surface of the back polymer layer and ensure that there are no bubbles in the polymer dry film in the through hole 4. The polymer dry film is made of a polymer dry film material with a high dielectric constant, low dielectric loss, high breakdown voltage, high surface resistance and volume resistance. In a negative pressure environment, the polymer dry film material will soften and have a certain fluidity when heated to a certain temperature. For example, the polymer dry film material can be selected from the S2000 series, EMS series, etc. For products with low electrical requirements, epoxy dry films such as SU8 can also be selected.

[0086] The pressure of vacuum lamination can be determined according to the material and product structure of the polymer dry film, and the temperature can be determined according to the material and product structure of the polymer dry film.

[0087] S5. Use photolithography to define the pattern, define the back scribe groove 5 and the polymer dry film layer window 12 in the through hole 4, ensure that the polymer dry film layer in the through hole 4 has a uniform thickness and does not fall off, and ensure that the back scribe groove 5 and the front scribe groove 8 are relative to each other.

[0088] The polymer dry film with a thickness of 2um to 10um bonded to the side wall of the through hole 4 is exposed, and the rest of the polymer dry film in the through hole is not exposed. The unexposed polymer dry film is then developed and removed by development, thereby achieving window opening, retaining the polymer dry film bonded to the side wall of the through hole 4, forming a window 12 of the polymer dry film layer in the through hole 4, thereby forming a first polymer layer 2 corresponding to Example 1.

[0089] S6. Figure 6As shown, a metal seed layer is sputtered on the back of the integrated circuit and electroplated, the thickness of the electroplated film layer on the back of the substrate 1 is 1um to 15um, and then the metal wire layer pattern on the back of the substrate 1 is defined by photolithography, and finally the first conductor layer 3 on the back of the integrated circuit chip is etched by wet etching. In the whole process, it is necessary to ensure the thickness, continuity, adhesion, etc. of the metal seed layer, and ensure the thickness, uniformity, and continuity of the electroplated layer in the through hole 4.

[0090] The thickness of the electroplated layer in the through hole 4 is divided into two types according to different electroplating methods: one is to directly electroplate 1um to 10um of a metal with good conductivity on the side wall (i.e., the inner wall of the polymer dry film layer window 12); the other is to fill the entire through hole 4 (i.e., the inside of the polymer dry film layer window 12) with metal by electroplating, and ensure that the thickness of the first conductor layer 3 on the back of the substrate 1 is 1um to 15um.

[0091] S7. If necessary, the processing can be continued on the basis of step S6, such as forming an I / O bump or I / O pad on the back of the substrate 1. In addition, wafer stacking or stacking other logic chips, digital chips, MEMS chips or their combinations on the wafer can also be performed. After completing the above processing, a single wavelength of light (e.g., ultraviolet light) is used to irradiate the surface of the support sheet 11 to separate the bonding glue and the photosensitive glue, forming a wafer as shown in FIG. Figure 1 The structure shown.

[0092] The above examples are used to illustrate the specific implementation of the present invention. However, the protection scope of the present invention is not limited to the above exemplary implementation. Any modification, equivalent substitution, improvement, etc. made by those skilled in the art within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A semiconductor device, characterized in that: The semiconductor device comprises: Substrate (1); A through hole (4) extending through the substrate in a thickness direction; A first polymer layer (2) which continuously covers at least the inner wall of the through hole (4); a first conductor layer (3) which continuously covers at least the inner wall of the first polymer layer (2); and A first electrode (6) is formed on the first surface of the substrate, and the first electrode is electrically connected to the first conductor layer (3).

2. The semiconductor device according to claim 1, wherein The first polymer layer (2) also covers at least a portion of the second surface of the substrate.

3. The semiconductor device according to claim 2, wherein: The first conductor layer (3) also at least partially covers the surface of the first polymer layer (2) located on the second surface.

4. The semiconductor device according to claim 1, wherein: The semiconductor device further comprises: A second polymer layer (7) covers at least a portion of the first surface of the substrate.

5. The semiconductor device according to claim 4, wherein: The semiconductor device further comprises: A second conductor layer (9) is located on the surface of the second polymer layer (7), and the second conductor layer (9) is electrically connected to the first electrode (6).

6. A method for manufacturing a semiconductor device, characterized in that: The manufacturing method comprises: At least a first electrode (6) is formed on a first surface of a substrate (1); A bonding glue (10) is applied on one side of the first surface of the substrate, a photosensitive glue is applied on the surface of a transparent support sheet (11), and the substrate and the support sheet are bonded together by the bonding glue and the photosensitive glue; Etching the substrate from the second surface of the substrate to form a through hole (4) penetrating the substrate in the thickness direction, wherein the first electrode (6) is exposed from the bottom of the through hole (4); Filling the through-hole with a polymer dry film; Performing a window opening process on the polymer dry film in the through hole (4) to form a first polymer layer (2) that at least continuously covers the inner wall of the through hole (4), wherein the inner periphery of the first polymer layer (2) has a through window (12), and the first electrode (6) is exposed from the bottom of the through window (12); A first conductor layer (3) is formed on the inner wall of the through window, which at least continuously covers the inner wall of the first polymer layer (2), and the first conductor layer (3) is in contact with the first electrode (6); and The photosensitive adhesive is irradiated with light having a predetermined wavelength through the support sheet to separate the bonding adhesive from the photosensitive adhesive.

7. The method for manufacturing a semiconductor device according to claim 6, wherein: Before bonding the substrate and the support sheet, a second polymer layer (7) and a second conductor layer (9) are formed on the first surface of the substrate. The second conductor layer (9) is located on the surface of the second polymer layer (7), and the second conductor layer (9) is electrically connected to the first electrode (6).

8. The method for manufacturing a semiconductor device according to claim 6, wherein: The polymer dry film also covers at least a portion of the second surface of the substrate.

9. The method for manufacturing a semiconductor device according to claim 8, wherein: The first conductor layer (3) also at least partially covers the surface of the first polymer layer (2) located on the second surface.

10. The method for manufacturing a semiconductor device according to claim 6, wherein: The polymer dry film is filled into the through hole by using a vacuum lamination method.

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