JP2005268297A - High frequency device and its fabrication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an extremely small high frequency device having substantially same size as that of a functional element chip. <P>SOLUTION: The high frequency device comprises: a device chip 30; a functional element part 22 and an internal connection electrode 23 provided on the device chip 30, a gap 70 formed around the functional element part 22; a sealing resin layer 60 provided to surround the air gap 70, and an external connection electrode 40 to be connected with an internal connection electrode 23, wherein the sealing resin layer 60 is provided on the side for forming the functional element part above the device chip 30 to bury the internal connection electrode 23 and the air gap 70, and the external connection electrode 40 is carried on the outer surface of the sealing resin layer 60. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a high-frequency device that requires a gap in a functional element such as a surface acoustic wave device, a piezoelectric thin film device, and a microminiature mechanical switch, and a manufacturing method thereof, and more particularly to a miniaturized packaging technique.

  Among ultra-small high-frequency devices mounted on cellular phones and the like, surface acoustic wave devices, piezoelectric thin film devices, ultra-small mechanical switches, and the like require a gap in their functional element portions. Conventionally, a functional element chip is bonded face-up to a ceramic casing, internal electrodes are connected by wire bonding, and then sealed and mounted by seam welding or soldering using a metal cap.

  Recently, in order to reduce the size of a device, a small package device in which a functional element chip is flip-chip bonded (face-down bonding) to a wiring substrate and sealed with a resin or the like has been disclosed.

  Taking the surface acoustic wave (SAW) device disclosed in Patent Document 1 as an example, it has a package structure as shown in FIG. The internal connection electrode 23 of the surface acoustic wave chip 20 is connected to the wiring substrate 30 on which the wiring pattern 41 and the external connection electrode 40 are formed by flip chip bonding via bumps 50.

The outer peripheral portion of the surface acoustic wave chip 20 is sealed with a sealing resin layer 60, and a gap 70 is formed between the comb electrode 22 of the surface acoustic wave chip 20 and the wiring board 30 to ensure the surface acoustic wave transmission function. It has a structure that can be done.
Republished patent WO97 / 02596

  In recent years, there has been an increasing demand for miniaturization of high-frequency devices mounted on portable devices such as cellular phones, and further miniaturization has been demanded. However, in the conventional package structure shown in FIG. 5, a sealing resin layer 60 having a predetermined thickness is required from the outer surface of the surface acoustic wave chip 20 to the periphery thereof, and so as to face the surface acoustic wave chip 20. Since the wiring board 30 is provided and the air gap 70 is formed between the surface acoustic wave chip 20 and the wiring board 30, these are obstacles to downsizing of the thickness, width and depth of the high-frequency device.

  An object of the present invention is to eliminate such disadvantages of the prior art and provide an ultra-small high-frequency device having almost the same size as a functional element chip and a method for manufacturing the same.

In order to achieve the object, the first means of the present invention includes a device chip, a functional element unit such as a comb-shaped electrode provided on the device chip, an internal connection electrode, and a periphery of the functional element unit. In a high frequency device comprising a formed gap, a sealing resin layer made of, for example, an epoxy resin provided so as to surround the gap, and an external connection electrode connected to the internal connection electrode,
The sealing resin layer is provided on the functional element part forming surface side on the device chip, the internal connection electrode and the gap are embedded, and the external connection electrode is carried on the outer surface of the sealing resin layer It is characterized by this.

  According to a second means of the present invention, in the first means, the internal connection electrode and the external connection electrode are electrically connected by a bump, and the bump is embedded in the sealing resin layer. Is.

  According to a third means of the present invention, in the first means, the internal connection electrode and the external connection electrode are electrically connected through a contact hole having a metal film on the inner surface, and the contact hole is embedded in the sealing resin layer. It is characterized by being.

According to a fourth aspect of the present invention, there is provided a device chip, a functional element portion provided on the device chip, a gap formed around the functional element portion, and a sealing provided so as to surround the gap. In a method for manufacturing a high-frequency device comprising a resin layer,
Placing a foaming agent on the functional element portion;
Coating the whole of the device chip with uncured resin;
Applying energy from above the uncured resin, foaming the foaming agent to form voids around the functional element portion,
A step of curing the uncured resin by applying energy to form a sealing resin layer.

According to a fifth aspect of the present invention, there is provided a device chip, a functional element portion and an internal connection electrode provided on the device chip, a gap formed around the functional element portion, and surrounding the gap. In the manufacturing method of the high-frequency device comprising the sealing resin layer made and the external connection electrode connected to the internal connection electrode,
A step of repeatedly forming a set of the functional element portion and the internal connection electrode on the device wafer;
Placing a foaming agent on each functional element section;
Forming bumps on each of the internal connection electrodes;
Coating the entire device wafer with uncured resin;
Forming a void around the functional element portion by foaming the foaming agent;
Curing the uncured resin to form a sealing resin layer;
Polishing the surface of the sealing resin layer to expose the upper portion of the bump from the surface of the sealing resin layer;
Forming a metal film on the surface of the sealing resin layer;
Patterning the metal film to form the external connection electrodes;
Cutting and separating the device wafer into individual devices.

A sixth means of the present invention provides a device chip, a functional element portion and an internal connection electrode provided on the device chip, a gap formed around the functional element portion, and surrounding the gap. In the manufacturing method of the high-frequency device comprising the sealing resin layer made and the external connection electrode connected to the internal connection electrode,
A step of repeatedly forming a set of the functional element portion and the internal connection electrode on the device wafer;
Placing a foaming agent on each functional element section;
Coating the entire device wafer with uncured resin;
Forming a void around the functional element portion by foaming the foaming agent;
Curing the uncured resin to form a sealing resin layer;
Forming a contact hole reaching each internal connection electrode in the sealing resin layer;
Forming a metal film from the inner surface of the contact hole to the surface of the sealing resin layer;
Patterning a metal film formed on the surface of the sealing resin layer to form the external connection electrode;
Cutting and separating the device wafer into individual devices.

 A seventh means of the present invention is characterized in that, in the fourth to sixth means, the foaming agent is an azide compound or naphthalene.

 The eighth means of the present invention is characterized in that, in the fourth to sixth means, the curing rate of the uncured resin is slower than the foaming rate of the foaming agent.

 According to a ninth means of the present invention, in the fourth to sixth means, the foaming agent is foamed by irradiation with ultraviolet rays, and the uncured resin is cured by heating. .

 According to a tenth means of the present invention, in the first to third means, the high-frequency device is any one of a surface acoustic wave device, a piezoelectric thin film device, and a micro mechanical switch. .

The present invention has the following effects.
(1) Since the external connection electrode is formed on the sealing resin layer itself, the wiring board can be omitted and the thickness of the device can be reduced.

(2) Since the sealing resin layer can be formed in almost the same size as the functional element chip size, it is possible to reduce the size.

(3) Since it is a built-up method that is basically stacked on functional element wafers, assembly cost can be reduced and yield can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to drawings, particularly focusing on surface acoustic wave devices. FIG. 1 is an explanatory diagram of a packaging process of the surface acoustic wave device according to the first embodiment. This packaging process will be described in order.

 First, as shown in FIG. 2A, a surface acoustic wave wafer 21 made of a piezoelectric single crystal such as lithium tantalate or lithium niobate is prepared. On the wafer 21, a comb electrode 22 and an internal connection electrode 23 formed by patterning an Al sputtered film in advance are formed as a set, and are repeatedly formed along the longitudinal direction of the wafer 21.

 Next, as shown in FIG. 2 (2), a foaming agent 80 such as an azide compound or naphthalene that generates a gas by applying energy as described later or turns itself into a gas is printed or potted on the comb electrode 22. The comb-tooth electrode 22 is covered by selectively placing the electrode.

 Next, as shown in FIG. 3C, an Au bump 50 is formed on the internal connection electrode 23 by a wire bump bonding method to a predetermined height.

 Next, as shown in FIG. 4 (4), an epoxy-based uncured resin 61 is spin-coated or laminated to a predetermined thickness on the entire wafer 21 to which the foaming agent 80 and the bumps 50 are added. The bump 50 is covered.

 Next, as shown in FIG. 5 (5), the foaming agent 80 is foamed by irradiating energy 100 from above or on the uncured resin 61 by ultraviolet irradiation or heating alone or in combination. Form. When the void 70 is formed, since the uncured resin 61 is hardly cured, the foaming agent 80 can be foamed without any trouble.

 Subsequently, energy 100 is irradiated by ultraviolet irradiation or heating alone or in combination, and the uncured resin 61 is cured to form the sealing resin layer 60. The void 70 is reliably secured by this resin curing.

 The curing rate of the uncured resin 61 is adjusted so as to be slower than the foaming rate of the foaming agent 80, or the foaming of the foaming agent 80 is performed only by irradiation with ultraviolet rays, and then heated to be thermosetting uncured. The resin 61 may be cured.

 After the resin is cured, the surface of the sealing resin layer 60 is polished 110 to expose the upper portions of the bumps 50 from the surface of the sealing resin layer 60 as shown in FIG. The surface is flattened, and the sealing resin layer 60 on the gap 70 is left with a predetermined thickness.

 Next, as shown in FIG. 7 (7), the exposed part of the bump 50 and the surface of the sealing resin layer 60 are covered with an electroless plating film (metal film) of Cu or Ni, and patterned by a photoetching method for external connection. The electrode 40 is formed. Therefore, the sealing resin layer 60 also functions as a carrier for the external connection electrode 40, and the external connection electrode 40 is electrically connected to the internal connection electrode 23 through the bumps 50.

 Finally, dicing separation 90 is performed at the position indicated by the alternate long and short dash line in FIG. 7 to obtain the surface acoustic wave device 120 shown in FIG. As shown in FIG. 8 (8), a gap 70 is formed around the comb-shaped electrode 22 which is a functional element portion, and the sealing formed on the surface acoustic wave chip 30 so as to surround the gap 70. The resin layer 60 embeds the internal connection electrodes 23 and the bumps 50, and the external connection electrodes 40 are formed on the outer surface of the sealing resin layer 60.

 FIG. 2 is an explanatory diagram of a packaging process of the surface acoustic wave device according to the second embodiment.

  First, as shown in FIG. 1A, a surface acoustic wave wafer 21 made of a piezoelectric single crystal such as lithium tantalate or lithium niobate is prepared. On the wafer 21, a comb electrode 22 and an internal connection electrode 23 formed by patterning an Al sputtered film in advance are formed as a set, and are repeatedly formed along the longitudinal direction of the wafer 21.

 Next, as shown in FIG. 2 (2), a foaming agent 80 such as an azide compound or naphthalene that generates gas by applying energy or becomes gas itself is selected on the comb electrode 22 by printing or potting. The comb-tooth electrode 22 is covered.

 Next, as shown in FIG. 3C, an epoxy resin uncured resin 61 is spin coated or laminated on the entire surface of the wafer 21.

 Next, as shown in FIG. 4 (4), energy 100 is irradiated from above the uncured resin 61 by ultraviolet irradiation or heating alone or in combination to foam the foaming agent 80, and around each comb electrode 22. A void 70 is formed. Subsequently, the energy 100 is irradiated by ultraviolet irradiation or heating alone or in combination to cure the uncured resin 61 to form the sealing resin layer 60.

 The curing rate of the uncured resin 61 is adjusted so as to be slower than the foaming rate of the foaming agent 80, or the foaming of the foaming agent 80 is performed only by irradiation with ultraviolet rays, and then heated to be thermosetting uncured. The resin 61 may be cured.

 Next, as shown in FIG. 5 (5), a contact hole 140 is formed in the sealing resin layer 60 by irradiation with a laser beam 130 so as to reach the internal connection electrode 23 of each functional element.

 Next, as shown in FIG. 6 (6), the internal connection electrode 23 and the contact hole 140 are connected with a plating metal, and the surface of the sealing resin layer 60 is covered with a metal film by plating, and the metal film is selectively etched. The external connection electrode 40 is formed.

 Finally, dicing separation 90 is performed at the position indicated by the alternate long and short dash line in FIG. 6 (6) to obtain the surface acoustic wave device 120 shown in FIG. As shown in FIG. 7 (7), a gap 70 is formed around the comb electrode 22 which is a functional element portion, and the sealing formed on the surface acoustic wave chip 30 so as to surround the gap 70. The resin layer 60 embeds the internal connection electrode 23 and the metal layer in the contact hole 140, and the external connection electrode 40 is formed on the outer surface of the sealing resin layer 60.

 FIG. 3 is a block diagram of a micro mechanical switch (RF-MEMS) according to the third embodiment, and FIG. 4 is a block diagram of a piezoelectric thin film device (FBAR) according to the fourth embodiment. In these drawings, reference numeral 150 is a device chip, 160a and 160b are switch electrodes, and 170 is a piezoelectric film.

 Also in these devices, a void 70 is formed around the functional element portion, and the sealing resin layer 60 formed on the device chip 150 so as to surround the void 70 embeds the internal connection electrode 23 and the bump 50, External connection electrodes 40 are formed on the outer surface of the sealing resin layer 60.

  The present invention can be applied to a micro robot, a micro sensor, and the like that require a gap inside, in addition to a high-frequency device that requires a gap in a functional element such as a surface acoustic wave device, a piezoelectric thin film device, and a micro mechanical switch. .

It is packaging process explanatory drawing of the surface acoustic wave device which concerns on 1st Embodiment of this invention. It is packaging process explanatory drawing of the surface acoustic wave device which concerns on 2nd Embodiment of this invention. It is a block diagram of the microminiature mechanical switch which concerns on 3rd Embodiment of this invention. It is a block diagram of the piezoelectric thin film device which concerns on 4th Embodiment of this invention. It is a block diagram of the conventional surface acoustic wave device.

Explanation of symbols

21: surface acoustic wave wafer, 22: comb electrode, 23: internal connection electrode, 30: surface acoustic wave chip, 40: external electrode, 50: bump, 60: sealing resin layer, 61: uncured resin, 70: Void, 80: Foaming agent, 90: Dicing separation, 100: Energy, 110: Polishing, 120: Surface acoustic wave device, 130: Laser light, 140: Contact hole, 150: Device chip, 160a, 160b: Switch electrode, 170 : Piezoelectric film.

Claims (10)

A device chip, a functional element portion and an internal connection electrode provided on the device chip, a void formed around the functional element portion, a sealing resin layer provided to surround the void, In a high-frequency device having an external connection electrode connected to an internal connection electrode,
The sealing resin layer is provided on the functional element part forming surface side on the device chip, the internal connection electrode and the gap are embedded, and the external connection electrode is carried on the outer surface of the sealing resin layer A high-frequency device characterized by that. 2. The high frequency device according to claim 1, wherein the internal connection electrode and the external connection electrode are electrically connected by a bump, and the bump is embedded in the sealing resin layer. 2. The high frequency device according to claim 1, wherein the internal connection electrode and the external connection electrode are electrically connected by a contact hole having a metal film on an inner surface, and the contact hole is embedded in the sealing resin layer. A high frequency device. A high-frequency device comprising a device chip, a functional element portion provided on the device chip, a gap formed around the functional element portion, and a sealing resin layer provided so as to surround the gap In the manufacturing method,
Placing a foaming agent on the functional element portion;
Coating the whole of the device chip with uncured resin;
Applying energy from above the uncured resin, foaming the foaming agent to form voids around the functional element portion,
A step of curing the uncured resin by applying energy to form a sealing resin layer. A device chip, a functional element portion and an internal connection electrode provided on the device chip, a void formed around the functional element portion, a sealing resin layer provided to surround the void, In a method for manufacturing a high-frequency device including an external connection electrode connected to an internal connection electrode,
A step of repeatedly forming a set of the functional element portion and the internal connection electrode on the device wafer;
Placing a foaming agent on each functional element section;
Forming bumps on each of the internal connection electrodes;
Coating the entire device wafer with uncured resin;
Forming a void around the functional element portion by foaming the foaming agent;
Curing the uncured resin to form a sealing resin layer;
Polishing the surface of the sealing resin layer to expose the upper part of the bump from the surface of the sealing resin layer;
Forming a metal film on the surface of the sealing resin layer;
Patterning the metal film to form the external connection electrodes;
And a step of cutting and separating the device wafer into individual devices. A device chip, a functional element portion and an internal connection electrode provided on the device chip, a void formed around the functional element portion, a sealing resin layer provided to surround the void, In a method for manufacturing a high-frequency device including an external connection electrode connected to an internal connection electrode,
A step of repeatedly forming a set of the functional element portion and the internal connection electrode on the device wafer;
Placing a foaming agent on each functional element section;
Coating the entire device wafer with uncured resin;
Forming a void around the functional element portion by foaming the foaming agent;
Curing the uncured resin to form a sealing resin layer;
Forming a contact hole reaching each internal connection electrode in the sealing resin layer;
Forming a metal film from the inner surface of the contact hole to the surface of the sealing resin layer;
Patterning a metal film formed on the surface of the sealing resin layer to form the external connection electrode;
And a step of cutting and separating the device wafer into individual devices. The method for manufacturing a high-frequency device according to any one of claims 4 to 6, wherein the foaming agent is an azide compound or naphthalene. The method for manufacturing a high-frequency device according to any one of claims 4 to 6, wherein a curing rate of the uncured resin is slower than a foaming rate of the foaming agent. The method of manufacturing a high-frequency device according to any one of claims 4 to 6, wherein the foaming agent is foamed by ultraviolet irradiation, and the uncured resin is cured by heating. Production method. 4. The high-frequency device according to claim 1, wherein the high-frequency device is a surface acoustic wave device, a piezoelectric thin film device, or a micro mechanical switch.

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