JP2000323822A - Plastic fine ball arrangement substrate, manufacture thereof and method of forming bump electrodes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive plastic fine ball array substrate and a method of manufacturing the same wherein the fine ball array substrate is less deformable and sucking holes are less wearable, and to provide a bump electrode forming method capable of forming bump electrodes collectively on a semi-finished product such as a wafer using the plastic fine ball array substrate, when bumps are formed using the plastic fine ball array substrate. SOLUTION: An array substrate 10 provided on head 300 has a structure such that a plastic plate 10a is reinforced with a SUS304 stainless strip 10b, and is excellent in mechanical strength and thus less deformable. Using this substrate 10, fine balls corresponding to electrodes 3 of all semiconductor chips on, e.g. 6-inch wafer 4 are sucked and held with sucking holes 11, whereby bump electrodes are formed collectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micro-ball array substrate and a method of manufacturing the same, and more particularly, to a semiconductor chip,
The present invention relates to a micro-ball array substrate used for forming a bump by bonding a ball-shaped bump to an electrode pad such as TAB (Tape Automated Bonding) or a ceramic substrate, a method of manufacturing the same, and a method of forming a bump electrode.

[0002]

2. Description of the Related Art Conventionally, there are a wafer bump and a stud bump as bumps formed on an electrode pad on a semiconductor chip. Wafer bumps are used to form bumps in semiconductor devices at the wafer stage, and require complicated steps as a wafer process many times. Further, the stud bump is formed by performing ball bonding at the time of temporary bonding of the wire bonding one by one to the electrode pad of the semiconductor chip, and cutting the neck portion of the wire after the bonding to form the stud bump. Further, as a method of joining a bump to an inner lead of a film carrier, there is a transfer bump for joining a bump grown by plating on a substrate to the inner lead.

In contrast to the above-described conventional bump forming method, Japanese Patent Application Laid-Open No. H10-74768 proposes a method using conductive fine metal balls and transferring the fine balls to electrodes of a semiconductor chip. ing. Next, an example of a bump forming method using minute balls will be described.

FIG. 5 shows a schematic configuration of an apparatus used in this method. This apparatus has a ball pickup stage 100, a joining stage 200,
An array head 300 and a driving mechanism 400 for moving the array head 300 in the X direction are provided. In FIG. 5, the direction perpendicular to the plane of the drawing is the Y direction, and the up-down direction is the Z direction, and it is possible to move in these Y and Z directions. In this apparatus, the arrangement head 300 moves between the ball pickup stage 100 (dotted line) and the joining stage 200 (solid line) as shown in FIG.

[0005] In the ball pickup stage 100, as shown in FIG. 6 (a), a large number of minute balls 1 are accommodated in a container 110. The microball 1 in the container 110 floats by vibrating the container 110 by the vibrator 120 or by air from an air discharge port opened at the bottom of the container 110. The minute ball 1 floating like this
As shown in FIG. 6B, the substrates are adsorbed and arranged by an array substrate 310 attached to the tip of the array head 300. In addition, suction holes 311 corresponding to the electrodes of the semiconductor chips on which the bumps are to be formed are formed in the array substrate 310, and one microball 1 is sucked and held in each suction hole 311.

Next, the array head 300 is driven by the driving mechanism 40.
0 to the bonding stage 200 (FIG. 6).
(C)). In the bonding stage 200, the array head 300 is mounted on the semiconductor chip 2 mounted at a predetermined position.
Are aligned and lowered to bring the microballs 1 held on the array substrate 310 into contact with the electrodes 3 of the semiconductor chip 2. In this case, the minute balls 1 can be bonded to the electrodes 3 as shown in FIG. In this example, a bump is formed on the electrode 3 of the semiconductor chip 2, but the bump is formed substantially in the same manner in the case of a TAB or ceramic substrate.

[0007] The array substrate 310 used in the conventional bump forming method using the minute metal balls as described above.
For example, 70-80 mm square and about 150 μm thick
SUS304 stainless steel sheet with a large number of suction holes 311 with a diameter of about 200 μm is used. Hereinafter, SU
It is conceivable that the thickness of the S304 stainless steel sheet will be 50 to 60 μm. In recent years, with the miniaturization and high performance of chip components, it has become necessary to finely drill the suction holes 311 with a small diameter in order to increase the pitch at which the suction holes 311 are formed. However, the SUS304 stainless steel sheet has a small diameter and fine suction hole 3 by etching or the like.
When the hole 11 is formed, a so-called hole defect may occur in which the suction hole 311 is not formed at a predetermined position. Therefore, instead of using a stainless steel plate such as SUS304 as the material of the array substrate 310, a material using a plastic plate on which fine suction holes can be formed by excimer laser has been proposed.

[0008]

However, the array substrate 3
When the above-mentioned plastic plate is used as 10, FIG.
Due to the lack of mechanical strength of the plastic plate itself, as shown in FIG.
In some cases, the central portion of the array substrate 310 was deformed to form a concave portion. When the central portion of the array substrate 310 is deformed to form a concave portion as described above, when the minute ball 1 in the container 110 is sucked, the distance from the minute ball 1 to the concave portion becomes long, and poor suction holding occurs. There was a risk of doing so. Further, as shown in FIG. 7B, when placing the micro-ball 1 on the semiconductor chip 2, the negative pressure is released, and conversely, compressed air PA is instantaneously supplied to the micro-ball 1 in the suction hole 311. Is forcibly released. However, due to the influence of the compressed air PA, the central portion of the array substrate 310 is deformed to generate a convex portion, and the semiconductor chip 2
The pressure on the central portion of the metal was increased, and there was a possibility that the bump height would vary.

Arranged substrate 31 made of the above plastic plate
Various disadvantages due to the deformation of 0 become remarkable especially when the area of the array substrate 310 increases. Therefore, this is a major problem in increasing the area of the array substrate 310 to improve production efficiency.

Furthermore, when the array substrate 310 made of the plastic plate is used, the end 311a on the opening side of the suction hole 311 is worn by repeated use as shown in FIG. There is a possibility that a defect or a suction holding defect may occur. For this reason, when the micro balls 1 are placed a predetermined number of times or more, the array substrate 310
Must be replaced with a new one, and the array substrate 310
There was also a risk that maintenance costs would increase.

The present invention has been made in view of the above problems, and a first object of the present invention is to provide a method for forming a micro ball array using a micro ball array substrate made of a plastic plate. An object of the present invention is to provide a low-cost plastic micro-ball array substrate in which deformation of the substrate, wear of the suction holes, and the like are reduced, and a method of manufacturing the same. It is a second object of the present invention to provide a bump electrode forming method capable of collectively forming bump electrodes on an intermediate product such as a wafer using the plastic micro-ball array substrate.

[0012]

In order to achieve the first object, a first aspect of the present invention is a plastic micro-ball array substrate having a large number of suction holes for sucking and holding conductive micro-balls. Wherein a metal reinforcing member having an opening corresponding to the suction hole is provided on the substrate surface on the opening side of the suction hole.

The plastic micro-ball array substrate has excellent mechanical strength and abrasion resistance because it has the metal reinforcing member on the substrate surface on the opening side of the suction hole. This can reduce the amount of deformation of the central portion of the array substrate caused by the negative pressure at the time of holding and holding the micro-balls and the pressure at the time of placing the micro-balls. It is possible to prevent variations in bump height due to a defect and an increase in the pressing force of the central portion when placing. In addition, since the micro-balls are sucked and held by the suction holes of the metal reinforcing member, there is little wear on the parts that come into contact with the micro-balls, and stable quality is maintained over a long period of time without occurrence of poor suction position or poor suction holding. It is possible to reduce the maintenance cost of the array substrate.

According to a second aspect of the present invention, in the plastic micro-ball array substrate according to the first aspect, the opening of the metal reinforcing member has a curvature extending toward the opening.

In this plastic micro-ball array substrate, when the plastic micro-ball array substrate carries the micro-balls, a part of the spherical surface of the micro-balls and the opening having a curvature are securely brought into close contact with each other. I do. Thereby, the micro-balls can be reliably arranged and carried on the plastic micro-ball array substrate.

According to a third aspect of the present invention, there is provided a method of manufacturing a plastic micro-ball array substrate having a large number of suction holes for sucking and holding conductive micro-balls, wherein the plastic material can be processed by an excimer laser. Using a plate, after drilling an opening at a predetermined position in the plastic plate with an excimer laser, a metal reinforcing member is bonded, and a surface of the metal reinforcing member other than the surface where the plastic plate is bonded is masked, An etching process is performed with an etching solution, and a portion corresponding to the opening formed in the plastic plate is etched to form an opening in the metal reinforcing member.

In the method of manufacturing a plastic micro-ball array substrate, the plastic plate having an opening at a predetermined position is bonded to the metal reinforcing member, and the plastic plate of the metal reinforcing member is bonded. The surface other than the bent surface is masked, and an etching process is performed using the above-mentioned etching solution. The etching solution does not etch the masked portion of the plastic plate or the metal reinforcing member, but etches only the portion of the metal reinforcing member corresponding to the opening of the plastic plate to form an opening. As a result, a plastic array substrate having openings formed therein can be manufactured.

According to a fourth aspect of the present invention, in the method for manufacturing a plastic micro-ball array substrate according to the third aspect, the metal reinforcing member is perforated by performing the etching process for a predetermined time to make it over-etched. A curved portion extending toward the opening is formed in the opening.

In this method of manufacturing a plastic micro-ball array substrate, the above etching process is performed for a predetermined time, whereby an over-etched state is formed, and a curved portion extending toward the opening is formed in the opening formed in the metal reinforcing member. can do.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a plastic micro-ball array substrate having a large number of suction holes for sucking and holding conductive micro-balls, wherein an opening is formed at a predetermined position. By using a metal reinforcing member, the metal reinforcing member is attached to a plastic plate, and a laser is irradiated from the metal reinforcing member side, so that the plastic plate has an opening formed in the metal reinforcing member. It is characterized in that corresponding openings are perforated.

In the method of manufacturing a plastic micro-ball array substrate, a metal reinforcing member having an opening at a predetermined position is bonded to a plastic plate, and a laser is irradiated from the metal reinforcing member side. The laser is blocked by the metal reinforcing member, but passes only through an opening formed in the metal reinforcing member to form an opening in the plastic plate. As a result, a plastic array substrate having openings formed therein can be manufactured.

In order to achieve the second object, the invention according to claim 6 is directed to an intermediate product in which conductive micro balls arranged and carried on a plastic micro ball array substrate are not divided into a plurality of parts. A bump electrode forming method of forming a plurality of bump electrodes at a time by transferring the bumps to the bump electrode forming surface, wherein the micro balls are arranged by the plastic micro ball array substrate through the suction holes corresponding to the bump electrodes. And a step of joining the bump electrode forming surface of the intermediate product and the micro balls arranged and supported on the plastic micro ball array substrate.

In this bump electrode forming method, the micro balls are arrayed and carried by the plastic micro ball array substrate through the suction holes corresponding to the plurality of bump electrodes.
The surface of the intermediate product on which the bump electrodes are formed is bonded to the micro balls arranged and carried on the plastic micro ball array substrate. This makes it possible to collectively form a plurality of bump electrodes on the bump electrode formation surface of the intermediate product.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment 1] Preferred embodiments of a micro-ball array substrate according to the present invention will be described with reference to the drawings, in which members substantially the same as or corresponding to those of the conventional example are denoted by the same reference numerals. Will be described.

First, the basic configuration of the bump forming apparatus used in this embodiment is substantially the same as that of the conventional apparatus (FIG. 5).
And the same. That is, it includes the ball pickup stage 100, the joining stage 200, the arrangement head 300, and the drive mechanism 400 for moving the arrangement head 300 in the X direction shown in FIG.

FIG. 1 shows a configuration of a main part in this embodiment. An array substrate 10 for arraying and carrying the conductive micro-balls 1 is attached to the tip of the array head 300. The array substrate 10 has suction holes 11 corresponding to the electrodes of all the semiconductor chips of the wafer 4 having a size of, for example, 6 inches. The micro balls 1 are arranged and supported through the suction holes 11. And the micro balls 1 are joined together.

FIG. 2 shows an example of the configuration of the array substrate 10 used in this embodiment. The suction holes 11 corresponding to the electrodes 3 of each semiconductor chip 2 are provided for every semiconductor chip 2 of the wafer 4. Has been drilled. The principle of sucking and holding micro balls in each suction hole 11 is substantially the same as that of the conventional example, that is, sucking and holding one micro ball in each suction hole 11 connected to a negative pressure source (not shown). That is.

As shown in FIG. 1, the array substrate 10 uses a plastic plate 10a made of, for example, polyimide, and a reinforcing member for securing a certain mechanical strength on the substrate surface (lower side) of the plastic plate 10a. As, for example, S
The configuration is such that a thin US304 stainless steel plate 10b is provided. Thus, the plastic plate 10a is SUS30
By reinforcing with the thin stainless steel plate 10b, deformation can be minimized even if the area of the array substrate 10 is increased. Further, since the minute balls 1 are sucked and held by the suction holes 11b formed in the SUS304 stainless steel thin plate 10b as the reinforcing member, wear of the suction holes 11b can be reduced. Furthermore, SUS which is a reinforcing member
A curved portion is provided on the opening side (lower side) of the suction hole 11b of the 304 stainless thin plate 10b.
One micro ball 1 can be surely held by suction at b.

Next, the operation of forming bumps on a plurality of semiconductor chips on a wafer at once by the bump forming apparatus provided with the array substrate 10 according to the present invention will be described. For example, on the side of the wafer 4 on which the bumps are to be formed, a plurality of semiconductor chips 2 are included on the wafer, and a portion corresponding to the electrode 3 of the semiconductor chip 2 is coated with flux in advance. I do. When the present invention is applied to such a wafer, the micro-balls 1 arranged and carried on the array substrate 10 are collectively collected without dividing the electrodes of the semiconductor chips on the wafer 4 which is the parts to be joined of the micro-balls 1 without dividing the area. To join.

First, in the ball pickup stage 100 shown in FIG. 5, the minute balls 1 are sucked and held by the array substrate 10 of the array head 300. In this case, the micro-balls 1 corresponding to the electrodes 3 of all the semiconductor chips 2 on the wafer 4 are suction-held by the suction holes 11 in the array substrate 10 (see FIG. 2). Here, as shown in FIG. 1, the array substrate 10 has a configuration in which the plastic plate 10a is reinforced with the SUS304 stainless steel thin plate 10b. Can be minimized due to the negative pressure for suction holding. The suction state of the minute balls 1 on the array substrate 10 can be confirmed by a pressure sensor connected to a negative pressure source (not shown). In this case, the minute balls 1 corresponding to the electrodes 3 of all the semiconductor chips 2 can be confirmed at once.

Next, the array head 300 shown in FIG. 5 is moved to the joining stage 200 by the driving mechanism 400. In the bonding stage 200, the arrangement head 300 is aligned with the wafer 4 placed at a predetermined position and lowered, and the micro balls 1 held on the arrangement substrate 10 are brought into contact with the electrodes 3 of the semiconductor chip 2. . Then, the negative pressure is released, and conversely, compressed air is momentarily supplied to forcibly release the holding of the minute balls 1 in the suction holes 11. Also in this case, since the array substrate 10 is reinforced as described above, the central portion of the array substrate 10 is not deformed by the influence of the compressed air to generate a convex portion.
Variations in bump height due to increased pressure on the center of the wafer 4 can be prevented. In addition, since the electrode 3 is coated with a flux in advance, the electrode 3 is appropriately pressed by the array substrate 10, whereby the micro-ball 1 is bonded to the electrode 3, and the bump 5 can be formed.

As described above, the bump forming apparatus provided with the array substrate 10 according to the present invention can form bumps on a plurality of semiconductor chips on a wafer at one time. The wafer 4 on which the bumps are formed is subjected to a reflow process, then cut by a dicing saw 6 as shown in FIG. 3A, and a semiconductor chip which can be surface-mounted on a substrate as shown in FIG. 3B. 2 isolated.

[Second Embodiment] Next, an example of a method of manufacturing the plastic micro-ball array substrate shown in the first embodiment will be described. FIGS. 4A to 4D are explanatory views showing the manufacturing process. First, a large number of small-diameter openings 11a are perforated at predetermined positions corresponding to the electrodes of a semiconductor chip by using ablation of an excimer laser on a plastic plate 10a having a thickness of about 1 mm. Specifically, the laser beam output from the excimer laser oscillator main body passes through a light shielding aperture mask having a predetermined shape, and is irradiated onto the plastic plate 10a through a light projecting lens, so that the laser beam has a predetermined shape. Opening 11a is formed.

At this time, the plastic plate 10a used
As materials of polyimide, polyester, epoxy,
For plastics such as polycarbonate that are easy to ablate, it is possible to process the opening as it is, using polyethylene, polypropylene,
For plastics that are difficult or impossible to process by ablation such as polyacetal and Teflon, a material that easily absorbs the wavelength of the excimer laser, such as fine carbon powder, is mixed to promote ablation. Processing can be performed.

Next, as a reinforcing member, the plastic plate 10a in which the opening 11a is formed is substantially the same size as the plastic plate 10a, for example, a thickness of 25 to 50.
A thin SUS304 stainless steel plate 10b of μm is bonded with an adhesive. And SUS304 stainless steel sheet 10
A masking layer 13 is formed by laminating the surface other than the surface bonded to the plastic plate 10a of FIG. b (FIG. 4A). Then, an etchant (such as ferric chloride)
Immersed in water and etched with ultrasonic waves (Fig. 4
(B)). At this time, the etching process is performed for a longer time to bring the over-etching state. By immersing in the etching solution and performing the etching process, the etching solution enters the opening 11a formed in the plastic plate 10a, and the portion of the SUS304 stainless thin plate 10b corresponding to the opening 11a has a curvature. Opening 11b
Can be formed (FIG. 4C). After the opening 11b is formed in the SUS304 stainless steel thin plate 10b in this manner, the opening 11b is washed and the etching solution or the masking layer 13 is formed.
Is removed to complete a plastic micro-ball array substrate (FIG. 4D).

[Third Embodiment] Next, another method of manufacturing the plastic micro-ball array substrate shown in the first embodiment will be described. First, a metal reinforcing member having a thickness of 25 to 50 μm and a large number of small-diameter openings formed in predetermined positions corresponding to the electrodes of the semiconductor chip is prepared by laser processing or the like. Then, this metal reinforcing member is about 1 mm thick.
And excimer laser is irradiated from the side of the metal reinforcing member. By irradiating the excimer laser from the metal reinforcing member side in this way, the metal reinforcing member functions as a mask material, and the excimer laser passes only through the opening formed in the metal reinforcing member. The excimer laser that has passed through the opening reaches the plastic plate, and the plastic plate is ablated to form the opening. By such a manufacturing method, a plastic micro-ball array substrate can be manufactured.

[0037]

According to the first and second aspects of the present invention, the plastic micro-ball array substrate has a metal reinforcing member on the substrate surface on the opening side of the suction hole. Excellent in nature. Thereby, the deformation of the array substrate can be reduced, and there is an excellent effect that it is possible to prevent defective holding of small balls and unevenness in bump height. Further, since the abrasion of the suction hole can be reduced, there is an excellent effect that stable quality can be maintained for a long period of time and maintenance cost can be reduced.

In particular, according to the second aspect of the present invention, since the opening of the metal reinforcing member has a curvature that spreads toward the opening, the opening can be in contact with a part of the spherical surface of the minute ball. In addition, there is an excellent effect that the minute ball can be surely sucked and held.

According to the third and fourth aspects of the invention, the etching liquid enters through the opening of the plastic plate, and the metal reinforcing member is etched to form the opening. Thereby, there is an excellent effect that it is possible to manufacture a plastic micro ball array substrate having excellent mechanical strength reinforced by the metal reinforcing member.

In particular, according to the fourth aspect of the present invention, by performing the etching process for a predetermined time, an over-etched state is formed, and a curved portion extending toward the opening side is formed in the opening formed in the metal reinforcing member. There is an excellent effect that you can.

According to the fifth aspect of the present invention, the laser beam that has passed through the opening formed in the metal reinforcing member forms the opening in the plastic plate. Thereby, there is an excellent effect that it is possible to manufacture a plastic micro-ball array substrate having excellent mechanical strength reinforced by a metal reinforcing member.

According to the invention of claim 6, the micro balls arranged and carried by the plastic micro ball array substrate are joined to the bump electrode forming surface of the intermediate product.
Thereby, there is an excellent effect that a plurality of bump electrodes can be collectively formed on the bump electrode formation surface of the intermediate product.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a plastic micro-ball array substrate according to the present invention.

FIG. 2 is a plan view showing an example of an array substrate according to the present invention.

FIG. 3A is an explanatory view showing a state in which a semiconductor chip is isolated by cutting a wafer with a dicing saw. (B) is an explanatory view showing an example of an isolated semiconductor chip.

4 (a) to 4 (d) are explanatory views showing steps for manufacturing a plastic micro-ball array substrate of the present invention.

FIG. 5 is a diagram showing a schematic configuration example of a bump forming apparatus.

FIGS. 6A to 6D are diagrams sequentially showing main steps in a bump forming apparatus.

FIG. 7A is a cross-sectional view showing a state in which a minute ball is sucked and held by a conventional array substrate. (B) is sectional drawing which shows the state which mounts the micro ball by the conventional arrangement substrate on a board | substrate.

FIG. 8 is a cross-sectional view showing wear of suction holes of a conventional array substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Micro ball 2 Semiconductor chip 3 Electrode 4 Wafer 5 Bump 6 Dicing saw 10 Array substrate 10a Plastic plate 10b SUS304 stainless thin plate 11 Adsorption hole 11a Suction hole of plastic plate 11b SUS304 Stainless thin plate adsorption hole 100 Ball pickup stage 200 Joining stage 300 Array Head 400 drive mechanism

Claims (6)

[Claims] 1. A plastic micro-ball array substrate having a plurality of suction holes for sucking and holding conductive micro-balls, wherein an opening corresponding to the suction holes is formed on a substrate surface on an opening side of the suction holes. What is claimed is: 1. A plastic micro-ball array substrate, comprising: a metal reinforcing member having a perforated portion. 2. The plastic micro-ball array substrate according to claim 1, wherein the opening of the metal reinforcing member has a curvature extending toward the opening side. 3. A method for manufacturing a plastic micro-ball array substrate having a large number of suction holes for sucking and holding conductive micro-balls, wherein a plastic plate which can be processed by an excimer laser is used as a plastic material. After perforating an opening at a predetermined position on a plastic plate with an excimer laser, a metal reinforcing member is bonded, a surface of the metal reinforcing member other than the surface where the plastic plate is bonded is masked, and an etching process is performed with an etching solution. And forming an opening in the metal reinforcing member by etching a portion corresponding to the opening formed in the plastic plate. 4. The method for manufacturing a plastic micro-ball array substrate according to claim 3, wherein the etching process is performed for a predetermined period of time to form an over-etched state. A method for manufacturing a plastic micro-ball array substrate, comprising forming a curvature portion extending on an opening side. 5. A method for manufacturing a plastic micro-ball array substrate having a large number of suction holes for sucking and holding conductive micro-balls, wherein a metal reinforcing member having an opening at a predetermined position is provided. Using, the metal reinforcing member is attached to a plastic plate, and by irradiating a laser from the metal reinforcing member side, an opening corresponding to the opening formed in the metal reinforcing member is formed on the plastic plate. A method for manufacturing a plastic micro-ball array substrate, characterized by perforating. 6. A method according to claim 6, wherein the conductive micro balls arranged and carried on the plastic micro ball array substrate are transferred to a bump electrode forming surface of an intermediate product before being divided into a plurality of parts, and the plurality of bump electrodes are collectively transferred. A method of forming a bump electrode, comprising: arranging and carrying micro balls by the plastic micro ball array substrate through suction holes corresponding to the plurality of bump electrodes; and forming a bump electrode forming surface of the intermediate product. Bonding the micro balls arranged and carried on the plastic micro ball array substrate.