JP2001110946A - Electronic device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an SAW device together with its manufacturing method wherein the waviness or deflection of a substrate sheet is suppressed, deflection of each substrate is suppressed as well, and the deformation of a bump is stabilized with no degradation in productivity. SOLUTION: An SAW chip 6 where a bump 5 is formed on an electrode 7, and a substrate 1 where an electrode 2 is jointed through the SAW chip 6 and the bump 5, constitute an SAW device where a silicon substrate is used as the substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electronic device packaging, and more particularly to SAW (Surface A).
and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a SAW device, which is an electronic device, is manufactured by forming a bump of a gold ball on an electrode of a SAW chip, and then bonding the bump to an electrode of a ceramic substrate by thermocompression combined with ultrasonic wave (hereinafter referred to as ultrasonic flip). Chip bonding) and then packaging. Hereinafter, the outlines thereof will be described with reference to the drawings.

FIG. 7 is an explanatory view showing a bump forming method for forming a bump on an electrode of a SAW chip. A gold wire 32 is connected to a capillary 31 from a capillary 31 using a wire bonder (not shown).
The gold ball 35 is produced by supplying the aluminum ball 34 of the AW chip 33 to the aluminum electrode 34, and is bonded to the aluminum electrode 34 by thermocompression bonding with the ultrasonic wave using the capillary 31. 32 is torn off to form a bump 36 of a gold ball.

[0004] As shown in FIG. 8 (the same parts as in FIG. 7 are denoted by the same reference numerals and their description is omitted), the SAW chip 33 on which the bumps 36 are formed is replaced with the bumps 36 formed thereon. With the surface facing down, it is suction-fixed to a bonding tool 41 of a flip chip bonder (not shown).
On the other hand, on a work stage 42 of the flip chip bonder, a substrate sheet 45 in which a plurality of ceramic substrates 44 each having a gold-plated surface on an electrode 43 are adsorbed and fixed, and
Heat to about 00 ° C. In this state, the flip chip bonder aligns the bump 36 formed on the aluminum electrode 34 with the electrode 43 of the ceramic substrate 44, drives the bonding tool 41 vertically downward, and moves the SAW chip 33 to 75 (gf / bump). The substrate sheet 45 is pressurized by the bonding load of (2). At the same time, ultrasonic vibration is applied at an output of 3 W for 800 ms, and the mutual electrodes 34 and 43 are joined via the bump 36.

After the joining, as shown in FIG. 9 (the same parts as those in FIG. 7 are denoted by the same reference numerals and their description is omitted), each ceramic substrate 44 is sealed with a metal cap 46. Thereafter, the substrate sheet 45 is divided into individual packages to obtain individual SAW devices.

The substrate of the SAW device itself is made of a piezoelectric material because of the characteristics of the SAW device that handles surface acoustic waves, and a piezoelectric ceramic plate such as PZT is widely used.

[0007]

However, as described above, since the substrate sheet on which the SAW device is mounted is made of ceramic, precise processing is difficult, and undulation and warpage are generated. For this reason, as a result of examining the deformation state of the bumps after the completion of the SAW device package, there have been cases where the bump height varies by about 30 μm in the same package.

[0008] As described above, when a bump having a deformed bump is directly bonded by flip chip bonding, a bonding failure often occurs.

In some cases, the undulation or warpage of the substrate sheet can be solved by dividing the substrate and then joining them individually, but in that case, the productivity is greatly reduced and the production process is difficult. Not preferred.

The present invention has been made in view of such problems, and suppresses undulation and warpage of a substrate sheet, and also suppresses warpage of individual substrates, so that bumps can be formed without lowering productivity. It is an object of the present invention to provide a SAW device capable of stabilizing a deformed state of a device and a method for manufacturing the same.

[0011]

According to a first aspect of the present invention, there is provided a semiconductor chip having electrodes, a substrate having wiring provided so as to be connectable to the electrodes of the semiconductor chip by bumps, and the substrate. And a cap that covers the semiconductor chip connected to the electronic device, wherein at least the surface of the substrate on which the wiring is provided,
An electronic device comprising a silicon material.

According to the second aspect of the present invention,
An electronic device comprising: a semiconductor chip having electrodes; a substrate having wiring provided to be connectable to the electrodes of the semiconductor chip by bumps; and a cap covering the semiconductor chip connected to the substrate. The electronic device is characterized in that the substrate is a multilayer wiring substrate made of a silicon material.

According to the third aspect of the present invention,
The electronic device is characterized in that the cap is formed of a silicon material.

According to the fourth aspect of the present invention,
The electronic device is characterized in that the electrode formed on the substrate is aluminum, gold, or an alloy containing any of them as a main component.

According to the fifth aspect of the present invention,
The electronic device is characterized in that the substrate is formed by bonding substrates made of a silicon material.

According to the means of the invention of claim 6,
A bump forming step of forming a plurality of bumps on an electrode of an electronic device, a bonding step of bonding each electrode of a substrate to the electronic device via the plurality of bumps formed in the bump forming step, and a bonding step of An electronic device comprising: a bonding step of bonding a sealing cap to a substrate after the step of bonding; and a separation step of cutting the substrate and the cap bonded by the bonding step at a time and separating the packages into individual packages. It is a manufacturing method of.

Further, according to the means of the invention of claim 7,
An opening is formed on the substrate by etching a workpiece formed of a layer made of a silicon material and a layer on which a wiring is formed, and the opening is covered with a conductive material to form a circuit using the wiring. A method for manufacturing an electronic device, comprising a step of forming a substrate.

Further, according to the means of the invention of claim 8,
A method of manufacturing an electronic device, comprising a step of manufacturing a cap for forming a concave portion by etching silicon.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, as an embodiment of the present invention, a structure of a SAW device as an electronic device and a manufacturing method thereof will be described with reference to the drawings.

FIG. 1 is a sectional side view showing the structure of a SAW device according to the present invention. Silicon substrate 1 as a substrate sheet
A front surface electrode 2 and a back surface electrode 3 of aluminum are formed on the front surface and the rear surface, respectively, and the electrodes 2 and 3 are electrically connected to each other through a through hole 4. The aluminum electrode 7 of the SAW chip 6 is joined to the surface electrode 2 via the bump 5 of a gold ball. Outside the SAW chip 6, a silicon cap 8 is adhered to the silicon substrate 1 with an epoxy-based adhesive to seal the SAW chip 6 and then package it to form a SAW device.

The silicon material forming the silicon substrate 1 is silicon or a silicon compound. The silicon substrate 1 made of silicon single crystal can be easily flattened by mechanical removal processing by polishing. In addition, dry etching, wet etching, RIE (Rea)
Since removal processing methods such as Ction Ion Etching and electrolytic polishing have been established, the silicon substrate 1 provided with the wiring is selectively processed, and
Flattening can be easily performed. Further, since the flattened surface layer of the silicon substrate 1 is oxidized to form SiO ₂ , the strength of the silicon substrate 1 is increased and the silicon substrate 1 is chemically stabilized. Therefore, when bonding a SAW chip to the silicon substrate 1, The surface of the silicon substrate 1 is preferably oxidized.

Next, a method of manufacturing a SAW device having the above structure according to the present invention will be described. The SAW device has a SAW chip 6 on a surface of a silicon substrate 1 which is a substrate sheet.
Are bonded via the bumps 5 of the gold balls, so that the silicon substrate 1 having the electrodes formed on the front and back surfaces 2 and 3 before the bonding and the SAW chip 6 having the bumps 5 formed on the aluminum electrodes 7 are respectively formed. Manufactured separately.

FIGS. 2A to 2E are explanatory views showing the steps of manufacturing the silicon substrate 1 as a substrate sheet. First,
As shown in FIG. 2A, two silicon substrates 1a, 1
The surface electrode 2 is formed by forming a mask on the surface of the silicon substrate 1a by using a film forming apparatus (not shown) and selectively forming aluminum on only a predetermined portion of the silicon substrate 1a. On the other silicon substrate 1b, a step portion 9 is selectively formed on the silicon substrate 1b by etching, and aluminum is embedded in the formed step portion 9 by plating or the like to form a back electrode 3. Further, the surface of the silicon substrate 1b on which the back electrode 3 is formed is polished to finish the silicon surface and the back electrode 3 into a flat surface.

Subsequently, as shown in FIG. 2B, the lower surface of one silicon substrate 1a (the side where the surface electrode 2 is not formed) and the upper surface of the other silicon substrate 1b (the back electrode 3 is The formed side is preferably adhered with an adhesive having high moisture resistance, for example, an epoxy adhesive. At this time, both surfaces of the silicon substrates 1a and 1b are flat surfaces, and the flatness of the surface layer of the silicon substrate 1 is maintained even after being joined and integrated.

The silicon substrate 1 can be flattened by a known process if at least the surface of the substrate is made of a silicon material. However, if the entire silicon substrate 1 is made of a silicon material, This is preferable in suppressing variations in the coefficient of thermal expansion in the thickness direction of the silicon substrate 1.

Therefore, in this state, the front electrode 2 and the back electrode 3 are formed on the surface and inside of the silicon substrate 1. The front electrode 2 and the back electrode 3 are formed at positions where they partially overlap in the thickness direction of the silicon substrate 1.

Next, as shown in FIG. 2C, a hole for communicating the front surface electrode 2 and the back surface electrode 3 of the silicon substrate 1 is processed from the front side of the silicon substrate 1 (above the front surface electrode 2). . The hole 4a can be processed by any known means such as wet etching with a solution of K0H or Na0H, dry etching such as plasma etching / RIE, or X-ray or laser. it can. Although the depth of the hole 4a to be processed needs to reach at least the back electrode 3 inside the silicon substrate 1,
It may be deeper than that. In that case, the processed hole 4a may penetrate to the back surface of the silicon substrate 1.

Next, as shown in FIG. 2D, the inner wall of the hole 4a penetrating the front electrode 2 and the back electrode 3 is plated with a conductive material to form a through hole having a conductive coating. 4 is formed. The through-hole 4 electrically connects the front surface electrode 2 and the back surface electrode 3.

Next, as shown in FIG. 2E, the silicon substrate 1 is polished one thinner by performing machining, etching or the like until the rear surface electrode 3 is exposed at a predetermined height from the rear surface side of the silicon substrate 1. Then, the back surface electrode 3 is formed on the back surface of the silicon substrate 1.

Note that the designation of the front surface electrode and the back surface electrode in the silicon substrate changes depending on which surface of the silicon substrate is used on the upper side in actual use. Is used as the front surface electrode, and the lower side is used as the back surface electrode. However, when the surface opposite to the above is used, the front surface electrode and the back surface electrode are reversed from the above case. Therefore, in that case, the surface electrode is exposed on the surface of the silicon substrate by polishing or the like.

Next, formation of the bumps 5 on the aluminum electrodes 7 of the SAW chip 6 will be described with reference to FIG. The bump 5 is formed using a wire bonder (not shown). That is, as the bonding wire 10, the diameter φ
A 25 μm gold wire is supplied from the capillary 11 onto the aluminum electrode 7 of the SAW chip 6 to form a gold ball 1 having a diameter of 70 μm.
Form 2 After bonding the gold ball 12 to the aluminum electrode 7 of the SAW chip 6 by using a capillary 11 by thermocompression combined with ultrasonic waves, the capillary 11 is raised and the bonding wire 10 is torn off to form a gold ball 12 having a diameter of 85 μm. The bump 5 is formed.

Next, the bonding of the SAW chip 6 on which the bumps 5 formed as described above are formed and the silicon substrate 1 on which the electrodes 2 and 3 are formed will be described. FIG. 4 is a side cross-sectional view showing the bonding between the SAW chip and the silicon substrate on which the electrodes are formed. This bonding is performed using a flip chip bonder (not shown).

First, the SAW chip 6 is suction-fixed to the bonding tool 13 of the flip chip bonder with the surface on which the bumps 5 are formed facing down. On the work stage 14 of the flip chip bonder, the silicon substrate 1
Is fixed by suction and heated to 200 ° C. In this state, the respective positions of the bump 5 formed on the aluminum electrode 7 of the SAW chip 6 and the surface electrode 2 formed on the surface of the silicon substrate 1 are detected using a position detection camera (not shown), and based on the results, The work stage 14 is moved to perform mutual alignment.

Thereafter, the bonding tool 13 holding the SAW chip 6 is lowered vertically downward, and the SAW chip 6 is pressed against the silicon substrate 1 with a bonding load of 60 (gf / bump 5). At the same time, ultrasonic vibration is applied by an ultrasonic vibrator (not shown) at an output of 1 W for about 300 ms to join the bump 5 and the surface electrode 2 of the silicon substrate 1.

Thereafter, as shown in FIG. 5 (the same parts as those in FIG. 4 are denoted by the same reference numerals and their description is omitted), the silicon cap 8 is coated with an epoxy-based adhesive and
The AW chip 6 is bonded to the silicon substrate 1 from the AW chip 6 side to perform packaging, thereby forming a SAW device group. In addition,
The silicon cap 8 is prepared in advance by wet etching with a K0H or Na0H solution, plasma etching, dry etching such as RIE, or the like.

The silicon cap 8 is made of a silicon material, so that it is easy to form a concave shape using a known etching method.
The formation of a cavity that covers the surface becomes easy. In addition, since the material is the same as that of the silicon substrate 1, distortion due to the difference in the coefficient of thermal expansion is eliminated, so that the environmental resistance of the package is further improved.

Thereafter, as shown in FIG. 6 (the same parts as those in FIG. 4 are denoted by the same reference numerals and their description is omitted), a group of SAW devices to which the silicon cap 8 is adhered and packaged. Is diced with a dicing blade 15 for each SAW device,
Separate AW devices individually.

As a result of examining the deformation state of the bumps of the SAW device package completed by the above-described method, the present invention uses a silicon substrate, and the silicon substrate is flat. It was confirmed that the variation in bump height was 5 μm or less.

In the above-described embodiment, an aluminum electrode is used as the electrode formed on the silicon substrate, but gold or an alloy containing these as a main component may be used as the electrode material other than aluminum.

As described above, in the present invention, a SAW device manufactured by forming a bump on an electrode of an electronic device, flip-chip bonding the bump to an electrode of a substrate, and sealing with a cap or the like, By using a silicon substrate having a high flatness as a substrate, it is possible to obtain a bonding state with good connection with little variation in bumps, and it has become possible to manufacture a thin SAW device with high yield.

According to the SAW device manufacturing method of the present invention, a bump is formed on an electrode of the SAW device,
This is flip-chip bonded to a silicon substrate sheet on which a plurality of silicon substrates are aggregated, and the cap sheet on which a plurality of sealing caps are aggregated is collectively adhered to the silicon substrate sheet. The individual packages are manufactured by cutting the bonded silicon substrate sheet and cap sheet for each processing location, so that the productivity is extremely high.

In the above embodiment, the SAW device has been described. However, the present invention is not limited to this, and it is also possible to provide other high-quality electronic devices.

[0043]

According to the present invention, the productivity of SAW devices can be increased by forming bumps uniformly and stabilizing the bonding by the bumps.

[Brief description of the drawings]

FIG. 1 is a sectional side view showing the structure of a SAW device according to the present invention.

2 (a) to 2 (e) are explanatory views showing steps for manufacturing a silicon substrate according to the present invention.

FIG. 3 is an explanatory diagram illustrating formation of a bump on a SAW chip.

FIG. 4 is a side cross-sectional view showing the bonding between a SAW chip and a silicon substrate.

FIG. 5 is a side sectional view in which a silicon cap is bonded to a SAW chip.

FIG. 6 is an explanatory diagram in which a SAW device group is diced and divided for each SAW device.

FIG. 7 is an explanatory diagram illustrating formation of a bump on a SAW chip.

FIG. 8 is a side cross-sectional view showing a conventional connection between a SAW chip and a silicon substrate.

FIG. 9 is a side sectional view showing a conventional SAW device group.

[Explanation of symbols]

1, 1a, 1b: silicon substrate, 2: front electrode, 3: rear electrode, 4: through hole, 5: bump, 6: SAW chip, 7: aluminum electrode, 8: silicon cap

Claims (8)

[Claims] 1. An electronic device comprising: a semiconductor chip having electrodes; a substrate having wiring provided so as to be connectable to the electrodes of the semiconductor chip by bumps; and a cap covering the semiconductor chip connected to the substrate. Wherein at least the surface of the substrate on which the wiring is provided,
An electronic device comprising a silicon material. 2. An electronic device, comprising: a semiconductor chip having electrodes; a substrate having wiring provided so as to be connectable to the electrodes of the semiconductor chip by bumps; and a cap covering the semiconductor chip connected to the substrate. Wherein the substrate is a multilayer wiring substrate made of a silicon material. 3. The electronic device according to claim 1, wherein the cap is formed of a silicon material. 4. The electronic device according to claim 1, wherein the electrode formed on the substrate is made of aluminum, gold, or an alloy containing any of them as a main component. 5. The electronic device according to claim 1, wherein the substrate is formed by bonding substrates made of a silicon material. 6. A bump forming step of forming a plurality of bumps on an electrode of an electronic device, and a bonding step of bonding each electrode of a substrate to the electronic device via the plurality of bumps formed in the bump forming step. And a bonding step of bonding the sealing cap to the substrate after the bonding step, and a separating step of cutting the substrate and the cap bonded by the bonding step at a time to separate them into individual packages. A method for manufacturing an electronic device. 7. An opening is formed in the substrate by etching a workpiece formed of a layer made of a silicon material and a layer on which a wiring is formed, and the opening is covered with a conductive material. 7. The method according to claim 6, further comprising a step of forming a substrate by forming a circuit using the wiring. 8. The method for manufacturing an electronic device according to claim 6, further comprising the step of manufacturing a cap for forming a concave portion by etching silicon.