JP2015119100A - Package and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a package which has a through electrode excellent in airtightness while suppressing a structural change due to high-temperature treatment.SOLUTION: In the package, substrates 2 and 3 made of an insulating brittle material are joined together, an electronic component 5 is housed in a cavity formed inside, and a through electrode 6 is provided in at least one of the substrates 2 and 3 so that the electronic component 5 is electrically connected to the outside of the cavity. The through electrode 6 is constituted of a metal containing copper as a main component. Voids 12 having a predetermined opening diameter are formed at the crystal grain boundaries of crystal grains 11 constituting the metal.

Description

  The present invention relates to a package having a through electrode for mounting and enclosing an electronic component, and a manufacturing method thereof.

2. Description of the Related Art As a package for mounting, enclosing, and storing an electronic component such as a sensor for measuring a mechanical quantity such as a vibrator and acceleration, a package composed of two substrates is widely used.
These substrates are called a base substrate for mounting electronic components and a lid substrate for sealing the base substrate as a lid, and an insulating material such as ceramics or glass is processed to form electrodes. In particular, the base substrate is provided with electrodes for electrical connection between an electronic component to be mounted and an external circuit board.

  These electrodes are produced by baking metal paste, thin film technology, etc., and a structure in which a through-hole is formed in the base substrate by embedding a metal in the through-hole is proposed. . For example, a glass substrate with a through hole formed as a base substrate, the through hole is filled with a silver paste, and used as a through electrode (Patent Document 1), or a glass substrate is provided with a through hole to reduce the metal pin. A method has been adopted in which a through-hole is formed by filling a through hole with a melting point glass and fusing the low melting point glass to integrate the metal pin and the glass substrate to thereby close the through hole (Patent Document 2). Furthermore, the taper-shaped through hole is heated to a temperature equal to or higher than the softening point of the glass as the base material, and is formed by pressure molding with a molding die made of a carbon material. A method of integrating the glass substrate and the metal pin by setting the glass substrate to a softening point or higher is also proposed (Patent Document 3).

  However, it is well known that downsizing and proximity of through electrodes are desired with recent downsizing of electronic components and downsizing of packages. In addition, strictness is required in terms of sealing performance of the through electrode in vibrators and mechanical quantity measuring sensors that are affected by the atmosphere.

  In the method of manufacturing a through electrode using a metal paste such as the above silver paste, in addition to being costly from the viewpoint of using silver, when using a glass substrate as a substrate, the silver paste is used due to the heat resistance of the glass substrate. Since it is necessary to set the firing temperature of the glass substrate to be equal to or higher than the softening point of the glass substrate, there is a problem that the substrate is deformed.

  In addition, in the method of embedding metal pins in the through holes, the shape of the pins to be embedded cannot be made free, so the planar shape on the inside and outside of the package is limited, and a new electrode is produced by a method such as photolithography. It was necessary to connect with a pin which is a through electrode.

  In addition, as a method for embedding the through-hole, a plating method can be cited. However, the through-hole embedding is incomplete, or a plated product generally used is a copper plating having a microstructure that occludes gas. Therefore, heat treatment for releasing the occluded gas is performed at a temperature of 400 ° C. or less so as to suppress the change in the fine crystal structure as much as possible (Non-patent Document 1).

  In addition, in the case of copper plating having a microstructure formed on the through electrode by a plating method, not only there is a large difference in thermal expansion coefficient from ceramics, glass, silicon, etc. which are substrates, but also physical property values resulting from the microstructure Due to the difference from the bulk material, problems such as deformation, peeling, and destruction were caused by heat applied when two substrates were joined.

JP 2002-124845 A JP 2003-209198 A JP 2011-166307 A

Journal of Japan Institute of Electronics Packaging 9 (2) 113-118 (2006)

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a package having a through electrode excellent in airtightness while suppressing structural changes due to high-temperature treatment.

The present invention employs the following means in order to solve the above problems.
In the package according to the present invention, an insulating brittle material substrate is bonded, an electronic component is accommodated in a cavity formed inside, and the electronic component is electrically connected to the outside of the cavity. A package in which at least one of the through electrodes is provided, wherein the through electrodes are made of copper or a metal mainly composed of copper, and a void having a predetermined opening diameter at a crystal grain boundary of the crystal grains constituting the metal. It is formed.
According to this package, a metal mainly composed of copper having crystal grains with excellent ductility and malleability is used for the through electrode, and at the same time, voids are present at the grain boundary, so that the temperature change and the heat change can be prevented. In addition to ductility and malleability, the mechanical strength of the through electrode and its vicinity can be increased by reducing the mechanical stress in the vicinity of the through electrode, in addition to ductility and malleability, to reduce the thickness and size of the package. In addition, high reliability can be achieved.

The package according to the present invention is characterized in that the opening diameter is 1/10 to 1/1000 of the grain size of the crystal grains.
The package according to the present invention is characterized in that the substrate is made of any one of glass, silicon having an insulating layer on the surface, and an insulating brittle material of ceramics.
According to this package, a metal mainly composed of copper having crystal grains having excellent ductility and malleability is used for the through electrode, and at the same time, the grain boundary is 1/10 to 1 / Since it has 1000 voids, the stresses generated between the through electrodes and the substrate due to temperature changes and thermal changes, in addition to ductility and malleability, are relaxed by the voids, and the through electrodes and their nearby machines Therefore, it is possible to increase the reliability in addition to making the package thinner and smaller.

The package manufacturing method according to the present invention is characterized in that the above-described package is manufactured by a manufacturing process including a growth process for growing the crystal grains and a generation process for generating the voids.
According to this package manufacturing method, a through electrode made of a metal having copper as a main component is formed by an electroplating method or the like capable of forming fine crystal grains having a large number of crystal defects, and then subjected to heat treatment. Since growth and voids are generated, it is possible to provide a method for manufacturing a package with enhanced mechanical strength in and around the through electrode.

The package manufacturing method according to the present invention is characterized in that the growth step and the generation step are heat treatments performed in a range of 400 ° C. to 600 ° C.
In this package manufacturing method, a through electrode made of a metal having copper as a main component is formed by an electroplating method or the like capable of forming fine crystal grains having a large number of crystal defects, and is subjected to heat treatment in a range of 400 ° C. to 600 ° C. Since the gas component remaining in the electrode is not affected without affecting the substrate, and the crystal grains are coarsened, a large number of voids can be generated at the crystal grain boundary. It is possible to provide a method for manufacturing a package with increased mechanical strength in the vicinity.

  ADVANTAGE OF THE INVENTION According to this invention, not only the electronic component enclosure package excellent in airtightness can be provided stably, but the thing excellent in thickness reduction and size reduction can be provided.

It is a figure which shows the outline | summary of the package concerning embodiment of this invention. It is a figure which shows a lid substrate shaping | molding process among the processes for producing the package concerning embodiment of this invention. It is a figure which shows a base substrate formation process among the processes for producing the package concerning embodiment of this invention. It is a figure which shows the form of a through-electrode among the base substrate formation processes among the processes for producing the package concerning embodiment of this invention. It is a figure which shows the process for producing an internal electrode among the processes for producing the package concerning embodiment of this invention among the base substrate formation processes. It is a figure which shows an electronic component mounting, sealing process, and an external electrode preparation process among the processes for producing the package concerning embodiment of this invention.

Embodiments according to the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating an outline of a package according to an embodiment of the present invention in which a tuning fork type crystal resonator is mounted and vacuum-sealed, and FIG. 1 (a) is a perspective view from above, and FIG. (B) is a figure which shows the outline | summary in the cross-sectional direction of main parts, FIG.1 (c) expands a through-electrode part.

The package 1 is configured by sealing and bonding a base substrate 2 made of borosilicate glass and a lid substrate 3 made of glass of the same material by a bonding layer 4.
In the package 1, a tuning fork type crystal resonator 5 as an example of an electronic component is enclosed in a state of being connected by a protruding electrode 8 provided on an internal electrode 7 connected to the through electrode 6. Is connected to the external electrode 9 on the outer surface of the base substrate 2.

  On the other hand, as shown in FIG. 1C, the through electrode 6 is composed of a conductive film 10, a large number of crystal grains 11 made of copper, and a void 12 between crystal grain boundaries formed by the crystal grains 11. Yes. A void means a minute cavity, space, pore, bubble or the like.

  The package 1 in which the tuning fork type crystal resonator 5 is mounted and enclosed is manufactured in a wafer state for taking a large number of base substrates 2 and lid substrates 2 to be the package 1, and the tuning fork type crystal resonator 5 which is a mounted component is prepared. After mounting and sealing, it is cut by individual packages.

  The process for manufacturing the package 1 in which such a tuning-fork type crystal resonator 5 is mounted and enclosed includes the lid substrate manufacturing process shown in FIG. 2, the base substrate manufacturing process shown in FIGS. 6 includes the electronic component mounting, sealing process and external electrode manufacturing process shown in FIG.

In the following, the cross section taken along the line AB in FIG. 1A shown in FIG.
In the lid substrate manufacturing step shown in FIG. 2, as shown in FIG. 2A, a blast mask layer 14 is formed on one surface of the borosilicate glass substrate 13 with a thick film photoresist, and FIG. As shown, the cavity 15 is formed by sandblasting.

  Further, after removing the blast mask layer 14 as shown in FIG. 2 (c), as shown in FIG. 2 (d), aluminum is formed on the surface of the borosilicate glass substrate 13 on which the cavity 15 is formed by sputtering. By forming the bonding layer 16 made of a film, the lid substrate 17 is manufactured.

  As shown in FIG. 3 and FIG. 4, the base substrate manufacturing process includes manufacturing the through electrode 6, forming copper coarsened crystal grains 11 and voids 12 constituting the through electrode 6, and further, forming the internal electrode 7. It consists of making.

  In the production of the through electrode 6 shown in FIG. 3, a non-through hole 19 is produced by sandblasting on one surface of the same borosilicate glass substrate 18 as the material used as the lid substrate 17 (FIG. 3A). A conductive layer 20 having a thickness of 50 nm and 500 nm is formed on the surface where 19 is opened by sputtering in the order of chromium and copper (FIG. 3B), and after applying a dry film photoresist on this surface, A plating resist layer 21 having a diameter smaller than the diameter of the non-through hole 19 is formed in the non-through hole 19 (FIG. 3C), and then wet plating is performed through the plating opening 22 of the plating resist layer 21. Thus, a copper plating layer 23 is formed (FIG. 3D).

  Further, the plating resist layer 21 is peeled off (FIG. 3E), and both sides of the borosilicate glass 18 are polished to produce a base substrate 25 having through electrodes 24 that represent metal surfaces on the front and back sides (FIG. 3). (F)).

  Next, the through electrode 24 shown in FIG. 4A is made of the crystal grains 25 of the copper grains 25 constituting the through electrodes 24 and formed by a growth process for growing the crystal grains. By holding at 500 ° C. for 3 hours (generation process), the coarsened crystal grains 26 shown in FIG. 4B and the opening diameter of 1/10 to 1/1000 of the size of the crystal grains 26 A through electrode 28 having a void 27 is formed. In holding in a vacuum furnace, a void 27 having a size of 1/10 to 1/1000 is formed when heat treatment is performed in the range of 400 ° C. to 600 ° C.

  Next, a chromium film 50 nm and a copper film 2000 nm are formed on one surface of the base substrate 25 in this order by sputtering to form a conductive film 29 (FIG. 5A), and then the through electrode 28 appears. A plating resist layer 31 having a desired opening 30 is formed by photoresist and photolithography (FIG. 5b)).

  FIG. 5 is a diagram showing the fabrication of the internal electrode in the base substrate fabrication process, in which nickel plating 1 μm and gold 0.05 μm are sequentially formed in the opening 30 by electroplating, and a plating layer 32 (FIG. 5C). Then, the plating resist layer 31 is peeled off (FIG. 5D), and by using the plating layer as an etching mask, unnecessary portions of the conductive film 29 are removed by etching, thereby forming the internal electrode 33, thereby forming the internal electrode 33. A base substrate 34 with 33 is prepared.

  In the electronic component mounting and sealing process, as shown in FIG. 6, a gold wire is wire-bonded on the internal electrode 33 on the base substrate 34, and a protruding electrode 35 is formed by cutting to a desired length. (FIG. 6A), the gold electrode portion of the tuning fork crystal resonator 36 is mounted on the protruding electrode 35, and the tuning fork crystal resonator 36 is attached to the base substrate 34 by bonding gold and gold by ultrasonic waves. It is mounted (FIG. 6B).

  Next, the lid substrate 17 is placed on the base substrate 34 on which the tuning fork type crystal resonator 36 is mounted, and anodic bonding is performed in vacuum through the bonding layer 16 made of aluminum, whereby the tuning fork type crystal resonator 36 is vacuum sealed. A plurality of stopped packages are produced in a wafer state.

  Next, a conductive silver paste is printed in a desired pattern including a portion of the through electrode 28 that is exposed on the outer surface of the base substrate 34, and the external electrode 37 is formed by heat curing. The wafer 38 is individually changed by mechanically separating the wafer by dicing, and a package 38 in which a tuning fork type crystal resonator 36 as a chip part is vacuum-sealed is manufactured.

  In the present embodiment, the through-holes are formed so that the front and back surfaces can be electrically connected to each other by polishing after copper plating is applied to the non-through holes formed in the base substrate material. A method may be used in which copper plating is applied to the shell and the through hole is sealed.

  In this embodiment, a method of creating a space in the central portion without completely filling the through-hole by copper plating is adopted, but the crystal grains are coarsened by heat treatment and voids are generated or excessive due to heat applied during bonding. This is to reduce the stress, and if there is no problem in strength, deformation, etc., the through hole may be completely embedded with copper plating.

  The package manufactured in this way has excellent ductility because the crystal grains are coarsened in the through electrode, and furthermore, since voids of an appropriate size exist at the crystal grain boundaries, Due to the deformation by the external force, the damage given to the brittle material such as glass, silicon, and ceramics as the substrate is reduced, so that the reliability is excellent.

  Furthermore, the thickness reduction during processing of each of the base substrate and the lid substrate is limited due to strength or the like, but in the present invention, as described above, it is excellent in reliability. Later, or after copper plating to form the through electrode, when polishing the base substrate and the lid substrate, it is possible to reduce the total thickness while suppressing damage to the substrate including the through electrode, making the package thinner and smaller A great effect can be achieved.

  In this embodiment, a tuning fork type crystal resonator is used as an electronic component. However, vacuum sealing or airtight sealing is required for semiconductor devices such as LSIs and mechanical quantity sensors such as acceleration sensors. Needless to say, the present invention can be applied to any electronic component.

  As described above, according to the present invention, a plurality of highly airtight packages in which electronic components are hermetically sealed in a wafer state can be simultaneously manufactured, and at the same time, it can be excellent in miniaturization and thinning. .

1, 38 Package 2, 34 Base substrate 3, 17 Lid substrate 4, 16 Bonding layer 5, 36 Tuning fork type crystal resonator 6, 24, 28 Through electrode 7, 33 Internal electrode 8, 35 Protruding electrode 9, 37 External electrode 10, 29 Conductive film 11, 25 Crystal grain 12, 27 Void 13, 18 Borosilicate glass substrate 14 Blast mask layer 15 Cavity 19 Non-through hole 20 Conductive layer 21, 31 Plating resist layer 22 Plating opening 23 Copper plating layer 26 Coarse Crystallized grain 30 opening 32 plating layer

Claims (5)

A substrate made of an insulating brittle material is bonded, and an electronic component is housed in a cavity formed inside, and a through electrode is provided on at least one of the substrates so that the electronic component is electrically connected to the outside of the cavity. Package,
The package characterized in that the through electrode is made of copper or a metal containing copper as a main component, and a void having a predetermined opening diameter is formed at a crystal grain boundary of a crystal grain constituting the metal.   The package according to claim 1, wherein the opening diameter is 1/10 to 1/1000 of the grain diameter of the crystal grains.   The said board | substrate is comprised with either the insulating brittle material of glass, the silicon | silicone which provided the insulating layer on the surface, and ceramics, The any one of Claim 1 or 2 characterized by the above-mentioned. package.   The method for manufacturing a package according to any one of claims 1 to 3, comprising a growth step of growing the crystal grains and a generation step of generating the voids.   5. The method for manufacturing a package according to claim 4, wherein the growth step and the generation step are heat treatments performed in a range of 400.degree. C. to 600.degree.

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