JP5144141B2 - Wiring pattern forming method and electronic component mounting package - Google Patents

Description

  The present invention relates to a technique for forming a wiring pattern. More specifically, the present invention relates to a substrate (hereinafter also referred to as a “package” for convenience) in which a region on which an electronic component such as a MEMS element is mounted is formed in a concave shape. The present invention relates to a wiring pattern forming method for forming a wiring pattern and an electronic component mounting package manufactured by using this wiring pattern forming method.

  In recent years, MEMS (Micro Electro-Mechanical Systems) elements, which are fine systems in which micro-sized sensors, actuators, and control circuits are integrated, have been mounted on packages. The size of the MEMS element itself is on the order of several μm. However, when actually used, the MEMS element is mounted on a substrate which is a package body and sealed with a cap. At that time, in order to reduce the size of the entire package (particularly in the height direction), a portion where the MEMS element is mounted on the substrate is formed into a recess (cavity) shape, and the MEMS element is mounted in the recess. In that case, in order to electrically connect the MEMS element mounted in the recess and the conductor portion formed on the upper surface of the substrate, it is necessary to form a continuous wiring from the bottom surface in the recess to the upper surface of the substrate. It becomes.

  If wiring is formed in such a stepped portion (portion extending from the bottom surface in the recess to the top surface of the substrate), the film thickness of the wiring may not be uniform for process reasons. In some cases, there is a risk of disconnection near the upper and lower ends of the stepped portion.

As a technique related to such a conventional technique, for example, in Patent Document 1, a step is provided in the middle of a concave portion on a side wall of a recess on a substrate, a resist is applied by spray coating, and a film thickness of a pattern formed on the side wall is inclined. Is made uniform.
Japanese Patent Laid-Open No. 11-45457

  As described above, in the conventional technique, as described in Patent Document 1, a resist is applied by spray coating in order to make the thickness of the wiring formed on the stepped portion (on the side wall slope) uniform. Things have been done.

  However, even when the resist is applied by spray coating, the resist itself has fluidity, so that the portion near the upper end of the stepped portion is thinner than other flat portions, or the stepped portion There is a problem that the thickness of the resist to be applied becomes non-uniform, for example, the thickness near the lower end is thicker than the upper end. For this reason, the thickness of the wiring pattern cannot be uniformly formed in the stepped portion, and the wiring may be disconnected in some cases. Therefore, the electronic component is connected to the wiring and operated. There was a problem that it could not function normally.

  The present invention was created in view of the problems in the prior art, and a wiring pattern forming method and an electronic component mounting package capable of forming a wiring pattern having a uniform thickness even on a substrate having a stepped portion. The purpose is to provide.

In order to solve the above-described problems of the prior art, according to the basic form of the present invention, a step of forming a first conductive film on a base material having a stepped portion, and a required thickness on the entire surface of the base material A step of attaching a porous sheet having a thickness; a step of impregnating the porous sheet with a resist; exposing and developing the porous sheet impregnated with the resist; look including a step of forming a wiring pattern, to form the wiring pattern step, the resist the registration list is patterned into the shape is removed to the required shape porous sheet impregnated, the porous forming a pattern portion quality sheet remained, second and forming a wiring pattern to form a conductive film, removing the porous sheet in which the resist is impregnated into the pattern portion, further A wiring pattern forming method and removing the exposed first conductive film, characterized in containing Mukoto is provided.

  In the wiring pattern forming method of the above aspect, the method further includes the step of forming a first conductive film on the base material before the porous sheet is attached, and the step of forming the wiring pattern includes the resist Patterning the porous sheet impregnated with a desired shape, removing the resist in the shape, forming a pattern portion where the porous sheet remains, and removing the porous sheet of the pattern portion A step of exposing the first conductor film; a step of forming a second conductor film on the exposed first conductor film to form a wiring pattern; and removing the porous sheet impregnated with the resist And a step of removing the exposed first conductive film.

  According to the wiring pattern forming method of the present invention, after forming a conductor film on a substrate having a stepped portion, a porous sheet having a uniform thickness is pasted on the conductor film. A resist is applied to the porous sheet. Therefore, the portion including the tapered portion from the bottom surface of the concave portion to the upper surface of the substrate, particularly the boundary portion of the tapered portion, has a uniform resist thickness with other portions without being thinned or interrupted. Thereby, even if it is wiring containing a taper part, it becomes possible to form thickness uniformly from the bottom face of a recessed part to the upper surface of a base material. As a result, a stable signal can be supplied to an electronic component such as a MEMS element placed on the package substrate, and the occurrence of malfunctions can be reduced.

  Moreover, in the wiring pattern forming method of the above aspect, further, before attaching the porous sheet, including a step of forming a first conductive film on the base material, the step of forming the wiring pattern, Patterning the porous sheet impregnated with the resist into a desired shape, removing the resist in the shape, and forming a pattern portion where the porous sheet remains; and a second conductor film on the pattern portion Forming a wiring pattern and removing the porous sheet impregnated with the resist, and further removing the exposed first conductor film.

  According to the wiring pattern forming method of the present invention, after forming a conductor film on a substrate having a stepped portion, a porous sheet having a uniform thickness is pasted on the conductor film. A resist is applied to the porous sheet. Thereafter, the resist is removed from a required portion for forming a pattern by patterning, and the conductor is formed with the porous sheet remaining in that portion. Thereafter, the resist is removed, the porous sheet is removed, and the conductor film is removed to form a wiring pattern. Thereby, removal of a porous sheet can be performed by one process, and a manufacturing process can be simplified.

In order to solve the above-described problems of the prior art, according to another aspect of the present invention, an area for mounting an electronic component is a package having a base material formed into a concave shape, from the bottom surface of the concave portion. Provided is an electronic component mounting package characterized in that a wiring having a uniform thickness is formed in a step portion over the upper surface of the base material, and the wiring has a conductor film filled in a porous sheet .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a cross-sectional view of an electronic component mounting package according to an embodiment of the present invention. In the example of FIG. 1, only the configuration of the substrate portion constituting the package body is illustrated for the sake of simplicity of description. As shown in FIG. 1, the base material 1 has the recessed part 3, and the wiring (10a, 10b) following the level | step-difference part ranging from the bottom face of a recessed part to the upper surface of a base material is formed. The thickness of the wiring is uniformly formed in the step portion. In the present embodiment, an electronic component such as a MEMS element is mounted in the recess 3 and used.

  Next, a method for manufacturing the electronic component mounting package of the present embodiment will be described.

  2 to 4 are a cross-sectional view and a plan view showing a method for manufacturing an electronic component mounting package according to an embodiment of the present invention. 2A to 2C, FIGS. 3B to 3C, and FIGS. 4A to 4C, a plan view of the electronic component mounting package is shown on the right side, and the left side is shown on the left side. Shows a cross-sectional view taken along line II in the plan view.

  First, as shown in FIG. 2A, a substrate 1 made of silicon having a recess 3 is prepared, and a conductor film 2 is formed on the substrate 1 so as to cover the recess 3.

  The recess 3 is formed by etching at a required position using, for example, a photolithography technique. The substrate 1 is not limited to silicon, but may be glass or ceramic. As the ceramic, for example, a ceramic containing aluminum oxide or aluminum nitride as a main component can be used. When the base material 1 is ceramic or glass, the recess 3 having a required shape is formed by cutting.

  Next, the conductor film 2 is formed on the substrate 1. As a material of the conductor film 2, for example, titanium (Ti), copper (Cu), or the like is used, which becomes a seed layer for plating processing when a wiring is formed later. The film thickness of the conductor film 2 is preferably a minimum film thickness that does not cause a film thickness distribution when electrolytic copper plating performed in a later step is performed. In addition, the film thickness is determined in consideration of the amount by which the film thickness is reduced by pickling performed as a pretreatment for plating. The conductor film 2 is formed by vapor deposition, sputtering, electroless plating, or the like.

The conductor film 2 may be formed after an insulating film such as SiO ₂ , polyimide, or an insulating resist is formed on the surface of the substrate 1.

  Next, as shown in FIG. 2B, a porous sheet 4 is pasted on the conductor film 2. The porous sheet 4 has pores of various sizes inside, and has a so-called “sponge” shape. For this reason, a liquid substance can be penetrated into the porous sheet 4 and filled in the pores. In addition, as the porosity is higher, the porous sheet has properties of other filled substances as a result of filling the pores with other substances. For example, when an insulating material is filled, the porous sheet 4 becomes an insulating sheet, and when filled with a metal material (paste-like) such as copper, the porous sheet 4 becomes a conductive sheet. For example, the porous sheet 4 is formed of polyethylene, polyimide, polyamideimide, or polyetherimide, and has a thickness of 5 to 200 μm, a pore diameter of 0.1 to 20 μm, and a porosity of 20 to 80%.

  This porous sheet 4 is stuck on the conductor film 2. In order to apply the porous sheet 4 on the conductor film 2 in an airtight manner, the conductor film 2 is wetted with water and attached using a vacuum laminator.

  Next, as shown in FIG. 2C, a resist is spray-coated on the porous sheet 4, and the porous sheet 4 is impregnated with the resist. By spraying the resist, fine particles of the resist are sprayed on the porous sheet 4 and the pores of the porous sheet 4 are filled with the resist, whereby the porous sheet 5 impregnated with the resist is obtained.

  When the resist is applied by spraying, the stage on which the package substrate is placed may be moved so that the resist is sprayed over the entire porous sheet. Thus, since the resist applied by spray coating fills the pores of the porous sheet 5 having a uniform thickness, the resist having a uniform thickness is formed on the upper surface of the conductor film 2. .

  In addition, the resist used here should just have tolerance with respect to the solvent etc. which are used in the removal of a porous sheet, and electrolytic copper plating so that it may mention later.

  Next, as shown in FIG. 3A, exposure and development are performed using a mask in which a required conductor pattern 22 is formed on a mask blank 21 to create a resist pattern. In the present embodiment, the exposed portion of the resist is made soluble, and the treatment with the aqueous solution is performed, and the resist of the required pattern portion is removed as shown in FIG. However, the porous sheet 6 remains. In other words, the porous sheet not impregnated with the resist exists only in the region extending from the tapered portion and the bottom surface of the concave portion 3 connected thereto and the upper surface of the base material 1, and the porous sheet 5 impregnated with the resist in the other regions. It will be covered.

  Note that it is not always necessary to use a mask for exposure, and exposure may be performed by directly drawing a conductor pattern shape using a laser beam or the like.

  Next, the porous sheet 6 remaining in the pattern forming portion is removed. The removal of the porous sheet 6 is performed using a solvent such as N-methyl-2-pyrrolidone. A solvent is apply | coated with respect to the pattern formation area | region of 6a-6d of FIG.3 (b), and a porous sheet is removed. As a result, as shown in FIG. 3C, the conductor film 2 is exposed at the pattern forming portion.

  Next, as shown in FIG. 4A, electrolytic copper plating is performed using the conductor film 2 as a seed layer, and a copper plating film (wiring pattern) 7 is formed on the exposed conductor film 2. In the electrolytic copper plating, the conductor film 2 is connected to the cathode, the copper plate is connected to the anode and immersed in a plating solution, a DC voltage is applied between both electrodes, and copper is deposited on the exposed conductor film 2. Form copper plating.

  Next, as shown in FIG. 4B, the resist is removed from the porous sheet 5 impregnated with the resist using an alkaline aqueous solution, and the porous sheet 5 is removed using a solvent such as N-methyl-2-pyrrolidone. To do. The porous sheet 5 may be removed by dipping in a solvent.

  Next, as shown in FIG. 4C, the pattern forming portion is covered with an etching resistant material, and the conductor film 2 is removed by an etching process. As a result, even if the required pattern region is a region including a taper from the bottom surface of the recess of the package substrate to the top surface of the substrate, wiring having a uniform film thickness is formed.

  As described above, according to the wiring pattern forming method according to the present embodiment, after a conductor film is formed on a substrate having a recess, a porous sheet having a uniform thickness is pasted on the conductor film. A resist is applied to the porous sheet. Therefore, the portion including the tapered portion from the bottom surface of the concave portion to the upper surface of the substrate, particularly the boundary portion of the tapered portion, has a uniform resist thickness with other portions without being thinned or interrupted. Thereby, even if it is wiring containing a taper part, it becomes possible to form thickness uniformly from the bottom face of a recessed part to the upper surface of a base material. As a result, a stable signal can be supplied to an electronic component such as a MEMS element placed on the package substrate, and the occurrence of malfunctions can be reduced.

  In the present embodiment, the case where wiring patterns are formed at four locations (FIGS. 3 and 4) has been described as an example for simplification of illustration, but the number of patterns formed is not limited to this. The necessary number of wirings are appropriately formed in consideration of the wiring width and the number of terminals of the chip component to be mounted.

  In the above-described embodiment, the porous sheet 4 is pasted on the conductor film 2 and then a resist is applied to the porous sheet 4 (see FIGS. 2B and 2C). The applied porous sheet may be stuck on the conductor film 2. For example, the resist is applied to the porous sheet 4 by immersing the porous sheet 4 in a resist solution, and then lifting the resist from the resist solution and drying it. Thereby, the resist is filled in the pores of the porous sheet 4. The porous sheet filled with the resist in this way is pasted on the conductor film. Thereafter, a pattern having a uniform film thickness is formed at a required position by the steps described with reference to FIGS.

  In the above-described embodiment, the wiring forming portion is patterned to remove the porous sheet 6, and then copper is deposited on the conductor film 2 exposed by electrolytic copper plating to form a copper pattern (FIG. 3 (c) As another method, for example, copper plating may be performed while leaving the porous sheet 6 left. Hereinafter, an embodiment in this case will be described with reference to FIG. 5A to 5C, a plan view of the electronic component mounting package is shown on the right side, and a cross-sectional view taken along line II of the plan view is shown on the left side.

  FIG. 5A is the same as the process of FIG. 3B, and shows a state where a region including a taper is patterned. In this state, electrolytic copper plating is performed. In electrolytic copper plating, the conductor film 2 is connected to the cathode, the copper plate is connected to the anode and immersed in a plating solution, a DC voltage is applied between the two electrodes, and copper is deposited on the conductor film 2 to form the copper plating film. Form.

  FIG. 5B shows a state 8 in which electrolytic copper plating is performed on the package of FIG. 5A and a porous sheet is taken into the copper plating film. That is, the copper deposited on the conductor film 2 is filled in the pores of the porous sheet. Since the porous sheet is so-called sponge-like, the plating solution penetrates into the porous sheet. Of the pores of the porous sheet, the resist is removed from the pattern forming portion, but the pores in other portions are filled with the resist. Therefore, copper deposited by electrolytic copper plating is filled only in the vacancies in the region not filled with the resist.

  Next, as shown in FIG. 5 (c), the resist is removed from the porous sheet 5 impregnated with the resist, and the porous material taken into the porous sheet and the copper plating film from which the resist has been removed using a solvent. Remove the quality sheet. Further, the copper plating film is covered with an etching resistant material, and the conductor film 2 is etched and removed. As a result, as shown in FIG. 5C, a copper pattern 9 having a taper with a uniform film thickness is formed.

  As described above, according to the embodiment shown in FIG. 5, after the conductor film is formed on the substrate having the recesses, the porous sheet having a uniform thickness is stuck on the conductor film. A resist is applied to the porous sheet. Thereafter, the resist is removed from a required portion for forming a pattern by patterning, and copper plating is performed with the porous sheet remaining in that portion. Thereafter, the resist, the porous sheet, and the conductor film are removed to form a wiring pattern. Thus, the removal of the porous sheet can be performed by a single process, and the manufacturing process can be simplified. Moreover, when removing a porous sheet partially, there exists a merit that the problem that the porous sheet of another part is removed with the solvent to be used can be avoided.

  Next, a configuration example in which electronic components are mounted on the package according to the above-described embodiment will be described with reference to FIG. FIG. 6 shows an example of a schematic configuration of a main part (substrate) of the package 15 in which a wiring including a taper is formed. As shown in FIG. 6, the package 15 is provided with a recess, and an electronic component 11a such as a MEMS element is mounted in the recess.

  In the package 15, wirings 10 a and 10 b are formed at positions that are electrically connected to electronic components. The wirings 10a and 10b are formed by the method described in the above embodiment.

  Electronic components 11a and 11b are arranged at predetermined positions on the substrate 1 on which the wirings 10a, 10b and 10c are formed. When placing the electronic component 11a, for example, bumps are formed on the connection terminal portions (pads) of the electronic component 11a so as to be connected to the pad portions on the wirings 10a and 10b formed on the substrate 1. In addition, when there is an electronic component 11b disposed on the upper surface of the substrate 1 and connection with the electronic component 11a disposed in the recess is necessary, it is electrically connected via the wiring 10b formed including the tapered portion. Connecting.

  As described above, in the package having the recess according to the present embodiment, the wiring including the taper is formed from the bottom surface of the recess to the upper surface of the base material, and the film thickness of the wiring is uniform. When forming this wiring, after forming a conductor film on a substrate having a recess, a porous sheet having a uniform thickness is pasted on the conductor film, and a resist is applied to the porous sheet. Therefore, the portion including the tapered portion extending from the bottom surface of the concave portion to the upper surface of the base material, particularly the boundary portion of the tapered portion, is formed in another flat portion without being thinned or interrupted. It becomes uniform with the resist thickness. Thereby, even if it is wiring containing a taper part, it becomes possible to form thickness uniformly from the bottom face of a recessed part to the upper surface of a base material. As a result, a stable signal can be supplied to an electronic component such as a MEMS element placed on the package substrate, and the occurrence of malfunctions can be reduced.

  In the above-described embodiment, the case where the wiring pattern is formed on the substrate in which the step portion includes one taper portion has been described as an example. However, as is apparent from the gist of the present invention, the step portion Of course, the form is not limited to this. For example, the present invention can be similarly applied even when the stepped portion includes two or more tapered portions.

FIG. 1 is a configuration diagram illustrating an example of a substrate portion of an electronic component mounting package. 2A to 2C are a cross-sectional view and a plan view (part 1) showing a method for manufacturing an electronic component mounting package. 3A to 3C are a cross-sectional view and a plan view (part 2) illustrating the method for manufacturing the electronic component mounting package. 4A and 4B are a cross-sectional view and a plan view (No. 3) showing the method for manufacturing the electronic component mounting package. FIGS. 5A to 5C are a cross-sectional view and a plan view (part 4) showing the method for manufacturing the electronic component mounting package. FIG. 6 is a diagram illustrating an example of a package on which electronic components are mounted.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material, 2 ... Conductor film, 3 ... Concave part 4, 6a, 6b, 6c, 6d ... Porous sheet, 5 ... Porous sheet filled with resist, 7, 9 ... Copper plating film, 8 ... Copper Porous sheet filled with

Claims (4)

Forming a first conductor film on a substrate having a stepped portion ;
Attaching a porous sheet having a required thickness to the entire surface of the substrate ;
Impregnating the porous sheet with a resist;
The resist is exposed and developed the impregnated porous sheet was patterned into a desired shape, seen including a step of forming a wiring pattern on the stepped portion,
The step of forming the wiring pattern includes:
Patterning the porous sheet impregnated with the resist into a required shape, removing the resist in the shape, and forming a pattern portion where the porous sheet remains; and
Forming a second conductive film in the pattern portion to form a wiring pattern;
Removing the porous sheet impregnated with the resist, and further removing the exposed first conductor film ;
A wiring pattern forming method comprising including Mukoto a. The wiring pattern forming method according to claim 1, wherein the step of impregnating the porous sheet with a resist includes spray-applying the resist over the entire surface of the porous sheet.   The porous sheet is made of polyethylene, polyimide, polyamideimide or polyetherimide, the pore diameter is selected from 0.1 μm to 20 μm, and the porosity is selected within the range of 20% to 80%. The wiring pattern forming method according to claim 1, wherein: The area where the electronic component is mounted is a package having a base material formed into a concave shape,
A package for mounting an electronic component, wherein a wiring having a uniform thickness is formed in a step portion extending from a bottom surface of the recess to an upper surface of the base material, and the wiring has a conductor film filled in a porous sheet.

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