KR20040086178A - Bump flattening device, bump flattening method and bump bonding device - Google Patents

Abstract

PURPOSE: A bump flattening apparatus, a bump flattening method and a bump bonding apparatus are provided to obtain a plurality of Au bumps with a uniform height by using a roller. CONSTITUTION: A bump flattening apparatus(12) includes a loading part, a roller, a roller driving mechanism, and a horizontally moving mechanism. The loading part(16) is used for loading a substrate(40) with a plurality of bumps. The roller(18) is used for pressing heads of the bumps. The roller driving mechanism is used for rotating the roller. The horizontally moving mechanism is used for moving horizontally the loading part. The loading part seems almost still under a lower end of the roller.

Description

Bump flattening device, bump flattening method and bump bonding device {BUMP FLATTENING DEVICE, BUMP FLATTENING METHOD AND BUMP BONDING DEVICE}

The present invention relates to a bump flattening device, a method and a bump bonding device for matching the height of bumps formed on a substrate.

DESCRIPTION OF RELATED ART Conventionally, the method of forming bump electrodes called bumps in the some electrode on a semiconductor element, and connecting the electrode on a semiconductor element and the electrode on a wiring board by this is known. The bump is obtained by attaching a metal in a molten state to an electrode on a semiconductor element. The semiconductor elements are attached to the wiring boards so that the bumps and the electrodes on the wiring boards are connected to each other, thereby electrically connecting them.

In order to make such a connection, it is preferable that the height of the head of a bump matches. This is because, when the heights of the bumps do not coincide, a poor connection occurs in some electrodes. Moreover, it is preferable that the upper surface (crushing surface) is substantially circular, and does not generate | occur | produce in the bump itself. If the crushed surface of the bumps is elliptical, the crushed surface, which is the contact surface, may protrude from the electrode of the wiring board, resulting in a short circuit or poor contact. Moreover, when a bump falls, the problem that the position of the dent surface which is a contact surface with a wiring board will shift | deviate. For this reason, conventionally, bump flattening is performed to conform the height to the shape after bump formation.

For example, Patent Literature 1 discloses a bump flattening apparatus that presses a semiconductor member having a plurality of bumps with a pressing member having a pressing surface to constantly match the height of the bumps. As a result, the heights of the plurality of bumps on the semiconductor element can be matched in a good shape. However, in the apparatus of patent document 1, there existed a problem that only the semiconductor element unit carved from the wafer can be plated. That is, after the bumps are formed in the state of the wafer, the bumps are sculpted and picked up for each semiconductor element to perform bump flattening. As a result, the overall process was complicated, and the production time of the semiconductor device was lengthening.

Here, the technique of expanding the press surface of the press member in patent document 1, and flattening with respect to the whole wafer can be considered. However, there are a great number of bumps formed on the entire wafer, and a very large pressing force is required to press all of them. The bump flattening device having such a pressing force is large in size and expensive, and lacks practicality.

As a solution to this problem, Patent Document 2 discloses a method of pressing a bump by moving a roller on a wafer on which a bump is formed. In this way, the bump can be pressed with a small force by moving while partially pressing with the roller.

(Patent Document 1)

Japanese Patent Laid-Open No. 2000-40766

(Patent Document 2)

Japanese Patent Publication No. 7-93305

However, in the method of patent document 2, there exists a problem that the shape of a bump is easy to be distorted. In other words, when moving while partially pressing with the roller, not only the pressing force in the vertical direction with respect to the head of the bump but also the force in the moving direction of the roller is imparted. Therefore, the bump head is flattened but at the same time stretched in the moving direction, and the crushed surface tends to be elliptical. In addition, the bumps themselves fall easily. In that case, various problems, such as a short circuit and a position shift, generate | occur | produce as mentioned above.

Accordingly, an object of the present invention is to provide an apparatus and method capable of forming bump bumps in a good shape with respect to a substrate on which a plurality of bumps such as a wafer are formed.

1 is a block diagram of a bump flattening device according to an embodiment of the present invention.

2 is a perspective view of the apparatus body of the bump flattening device.

3 is a side view of a gold bump to be subjected to flattening.

4 is a view of the wafer and the rotating roller viewed from above.

5 is a side view of bump flattening.

6 (A) is a side view of bump flattening, and FIG. 6 (B) is a top view of gold bumps.

Fig. 7A is a side view of the gold bump in which the collapse occurs, and Fig. 7B is a side view of the gold bump in which only the top surface is distorted.

(Explanation of the sign)

10 Bump Flattening Device 12 Gear Body

16 mounting table 18 rolling roller

18a bottom 20 moving unit

22 Shanghai Dong mechanism 24 rotary mechanism

26 Horizontal movement mechanism 28 Position angle detector

30 Speed detector 32 Roller drive mechanism

36 Main control part 38 Drive control device

40 wafer 42 sliding member

44 inclined member 46 gold bump

The bump flattening apparatus of this invention has a mounting base which mounts the board | substrate with which multiple bumps were provided in the upper surface, the rotating roller which presses the head of the bump on a board | substrate to the lower end, and the rotation drive mechanism which rotates a rotating roller. And a horizontal moving mechanism for horizontally moving the mounting table relative to the rotating roller, wherein the lower end of the rotating roller and the mounting table are relatively stopped.

Therefore, the roller can be moved while applying only the pressing force vertically downward with respect to the bump head part on a board | substrate. Thereby, the height of the head part of the bump formed in the board | substrate of high area, such as a wafer, can be matched in shape.

Although the substrate is preferably a wafer, for example, a semiconductor device or the like having a large number of bumps may be used. The material of the bump to be flattened is preferably a gold bump, but may be of a different material. The horizontal moving mechanism may move both the mounting table and the rotating roller as long as the mounting table is moved relative to the rotating roller. Moreover, relatively stopping the lower end part of a rotating roller and a mounting base relatively means to match the moving speed and direction of a rotating roller and a mounting base.

Embodiment of the Invention

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described.

1 shows a block diagram of a bump flattening apparatus 10 that is an embodiment of the present invention. This is roughly divided into the apparatus main body 12 and its control unit 14.

The apparatus main body 12 is comprised with the mounting base 16 for mounting the wafer 40, the rotating roller 18, and its peripheral mechanism. The mounting table 16 is provided with a moving unit 20 composed of a horizontal moving mechanism 26, a shank moving mechanism 22, and a rotating mechanism 24. By the driving force transmitted from this moving unit 20, the mounting base 16 is able to move horizontally, vertically, and rotationally. In addition, the position, the angle, and the moving speed of the mounting table 16 are detected by the respective detectors 28 and 30 and output to the control unit 14 described later. The control unit 14 calculates and outputs a signal for driving control to the mobile unit 20 based on the output information.

The rotary roller 18 is provided with a roller drive mechanism 32 for rotationally driving the rotary roller 18 and is driven based on a signal from the drive control device 38. In addition, the rotational speed of the rotary roller 18 is detected by the speed detector 34 and output to the main control unit 36.

The control part 14 calculates a control value based on the information from the drive control apparatus 38 which outputs the drive control signal of the moving unit 20, the roller drive mechanism 32, the speed detectors 30, 34, etc. The main control unit 36 is roughly divided. The main control unit 36 records the speed and the like detected by the position and angle detectors and the speed detectors 30 and 34, and calculates control values for drive control based on the information. The calculated value is output to the drive control device 38, and the drive control device outputs a drive control signal to the moving unit 20 and the roller drive mechanism 32 based on the value.

In addition, the bump flattening device 10 may be a single piece, or may be included or included in the bump bonding device.

Next, the apparatus main body 12 of the bump flattening apparatus 10 is demonstrated in detail using FIG. 2 is a perspective view of the apparatus body; In addition, in the figure, illustration is abbreviate | omitted about the motor attached to each moving mechanism and generating a driving force.

The rotary roller 18 is the rotary roller 18 of diameter 50mm provided above the mounting base 16, and can rotate about the axis of a X direction. The motor is attached to the rotating roller 18, and the rotation direction and speed of the motor are controlled by the drive control apparatus 38. FIG. Thereby, the rotation direction and speed of the rotating roller 18 are controlled.

The mounting table 16 is a stand for placing and holding the wafer 40, and a cutout 16a for positioning the wafer 40 is formed. When the wafer 40 is placed, the orientation flat of the cutout 16a and the wafer 40 are aligned. Moreover, in order to prevent the displacement of the mounted wafer 40, the mounting base 16 has the vacuum adsorption mechanism, and hold | maintains the wafer 40 by the adsorption force.

Furthermore, the mounting base 16 is provided with the rotating mechanism 24 which is not shown in figure, and the mounting base 16 can be rotated 360 degree in a horizontal plane. The drive of this rotating mechanism is also controlled by the drive control apparatus 38. In addition, the rotation angle is detected by the angle detector 28 and output to the main control unit 36.

The shank moving mechanism 22 is a driving means (not shown) which slides the sliding member 42 fixed to the mounting base 16, the inclined member 44 and the sliding member 42 provided in the lower direction to the Y direction. Consists of. The upper surface of the inclined member 44 is an inclined surface having a predetermined angle, and the upper surface position of the inclined member 44 increases as the front surface thereof becomes higher. The bottom surface of the sliding member 42 is an inclined surface at the same angle as that of the inclined member 44, and the upper surface of the inclined member 44 can be slid in the Y direction by the driving means. Then, by sliding the sliding member 42 on the upper surface of the inclined member 44, the mounting table 16 fixed to the upper surface of the sliding member 42 can be moved in the vertical direction. The movement distance and the direction of this sliding member 42 are controlled by the drive control apparatus 38, and the height of the mounting base 16 can be adjusted in 1 micrometer unit.

Under the inclined member 44, a horizontal movement mechanism 26 is provided. This is a moving stage for moving the inclined member 44 in the Y direction by a motor (not shown). By moving the inclined member 44, the mounting base 16 on the upper side thereof can be moved in the Y direction, that is, the direction that is perpendicular to the rotary roller 18.

In addition, in this embodiment, although the mounting base 16 was made to move, as long as it moves relatively with respect to the rotating roller 18, you may move the rotating roller 18. FIG. For example, the mounting table 16 may be fixed, and moving means for moving the rotating roller 18 in the horizontal and vertical directions may be provided. Moreover, the structure of that excepting the above may be sufficient as rotation, a horizontal, and a vertical movement mechanism. Moreover, although it is preferable that there exists a rotating and up-and-down moving mechanism, any one of the moving mechanisms may be lacking.

Next, the gold bump 46 and the wafer 40 to be flattened will be described. On the upper surface of the wafer 40, a plurality of gold bumps 46 having a shape are arranged.

The gold bump 46 before bump flattening has a shape in which its head protrudes small as shown in Fig. 3A, and its height h is about 60 mu m. However, this height is an approximate numerical value, and the height of the gold bumps 46 as a whole does not match. If it is attached to the wiring board in this state, connection failure occurs in some of the gold bumps 46. Therefore, in bump flattening, as shown in Fig. 3 (B), the gold bump 46 is crushed and flattened by small protrusions of the head, and the height thereof is matched. At this time, the height h of the gold bumps 46 is about 35 μm. That is, about 25 micrometers is crushed. At this time, it is preferable that the crushing surface 46a which is the upper surface of the gold bump 46 is almost circular, and the gold bump itself does not fall.

Also, for example, in a wafer 40 of an 8-inch, the gold bump 46, if formed at a rate of 1mm 8 per ² (8bump / mm ^2), the number of bumps is approximately 250 000 in the entire wafer 40 It becomes a dog. If a force of 1 N is required to press one of these gold bumps, a force of about 25.5 tons is required to press all of them to the surface simultaneously. It can be seen that a bump flattening device having such a pressing force is not practical. Therefore, as described later, bump flattening can be performed by moving while pressing with a roller capable of applying a pressing force.

Next, the flow of flattening the gold bumps 46 arranged on the upper surface of the wafer 40 using the bump flattening apparatus 10 will be described.

When flattening the gold bumps 46, the wafer 40 is first placed on the mounting table 16. In this case, the sliding member 42 is slid to move the mounting table 16 to the lowest position. Moreover, the horizontal moving mechanism 26 is driven to move the mounting base 16 to the position shifted from the rotating roller 18. In this state, the wafer 40 is placed on the mounting table 16. At this time, it mounts so that the notation part 16a provided in the mounting base 16 and the orientation flat of the wafer 40 may be aligned. The mounted wafer 40 is held by the vacuum suction means provided in the mounting table 16 and the position shift is prevented.

Next, the mounting table 16 is rotated by the rotation mechanism to adjust the angle of the wafer 40. This is adjusted at the angle at which the arranging directions of the rotary roller 18 and the gold bump 46 intersect. This will be described with reference to FIG. 4. 4 is a view of the wafer 40 and the rotating roller 18 placed on the mounting table 16 as viewed from the top. When the rotary roller 18 is made non-parallel to the arrangement direction of the gold bumps 46, the number of gold bumps 46 (indicated by black shading in the drawing) pressed by the rotary rollers 18 It can be seen that the rotation roller 18 and the arrangement direction are smaller than those in parallel. As described above, the gold bumps 46 are also required to press about 1 N, and in the case where the number of gold bumps to be pressurized is large, a larger pressing force is required. That is, when the rotational installation direction of the rotation roller 18 and the gold bump 46 is made parallel, a large pressing force is needed. Therefore, the mounting base 16 is rotated by the rotating mechanism so that the rotating roller 18 may become the direction which intersects the arrangement direction of the gold bump 46. As shown in FIG. Thereby, it can pressurize with little force.

Next, the rotating roller 18 is rotated and the mounting table 16 is horizontally reciprocated by the horizontal moving mechanism 26. In addition, at the time of return of reciprocation, the mounting base 16 is raised about 1 micrometer by making the sliding member 42 slide a small distance. In other words, the mounting table 16 is reciprocated horizontally while gradually reducing the distance between the rotary roller 18 and the mounting table 16. Thereby, the head part of the gold bump 46 can be pressed gradually.

This will be described in more detail with reference to FIG. 5. When the distance is shortened by 1 μm, the rotary roller 18 presses the head of the gold bump 46 by 1 μm. The pressurizing width d at that time can be represented by Formula (1) if the radius of the rotary roller 18 is R and the rising distance of the mounting table 16 is p.

Here, in this embodiment, since the radius of the rotating roller 18 is 25 mm, d becomes about 220 micrometers. That is, at any moment, the pressing surface of the gold bump 46 on the rotating roller 18 has a width of 220 占 퐉, and at this time, the number of the gold bumps 46 to be pressed is at most approximately equal to the above-described conditions. 350 pieces. In this case, the required pressing force is about 350N. In this manner, bump flattening can be performed at a small pressing force by pressing the line by the rotary roller 18 instead of pressing on the surface. Moreover, bump flattening of the whole large area like the wafer 40 can also be performed in a short time, in order to move this micro width | variety press surface by the movement of the mounting base 16. FIG.

Thus, by rotating the rotating roller 18 and horizontally moving the mounting base 16 by the horizontal moving mechanism 26, bump flattening of a large area can be performed with little force.

In addition, in this embodiment, although it moves up by 1 micrometer, the numerical value other than this may be sufficient. The rising distance p may be appropriately changed in accordance with the pressing force, the area of the wafer 40, the number of the gold bumps 46, or the flattening speed.

Next, the rotation speed of the rotary roller 18 at the time of pressurization, the moving speed and the direction of the mounting base 16 are demonstrated. The rotation of the rotary roller 18 and the movement of the mounting base 16 at the time of pressurization are performed at a speed and a direction in which the lower end of the rotary roller 18 and the head of the gold bump 46 relatively rest.

The rotary roller 18 is rotating at a constant speed, and the gold bumps 46 are also horizontally moved at a constant speed by the horizontal movement of the mounting table 16. Here, since the rotary roller 18 is large enough with respect to the gold bump 46, the movement of the lower end part 18a can be considered as substantially horizontal movement with respect to the gold bump 46. As shown in FIG. Therefore, if the moving speed of the mounting base 16 is made substantially the same as the rotating speed of the rotating roller 18, and the moving direction is the same, the lower end part 18a of the rotating roller 18 will have a gold bump ( Relatively close to the head of 46).

As such, when the lower end 18a and the head of the gold bump 46 are relatively stopped, only the pressing force in the vertical direction with respect to the gold bump 46 is applied. Therefore, the head part of the gold bump 46 is not rubbed by the rotation roller 18, and the shape of the crushed surface of the gold bump 46 is not distorted. That is, when the force in the moving direction is applied to the gold bump 46, as shown in Fig. 6A, the gold bump 46 is stretched in the moving direction, and the crushed surface thereof is shown in Fig. 6B. It is almost elliptical like In some cases, the gold bumps themselves may fall as shown in Fig. 7A. However, this problem can be prevented by applying only the pressing force in the vertical direction to the gold bump 46.

In addition, by repeating horizontal movement while gradually reducing the distance between the rotary roller 18 and the mounting table 16, it is possible to crush the head of the gold bump 46 gradually, thereby reducing the shape of the gold bump 46. Distortion is reduced. In other words, by relatively stopping the rotary roller 18 and the mounting table 16 as described above, it is possible to apply a pressing force only in the vertical direction, but in practice, a slight speed difference occurs. At that time, if the amount of crushing p is large, the influence of the speed difference becomes large. Therefore, the above-described problem occurs, and the crushed surface becomes elliptical, or the gold bumps easily fall. In addition, when the amount of crushing p is large, that is, when the pressing force is large, a pressing force much larger than the reaction force of the gold bump is applied. In this case, the pressing force does not spread all over the gold bumps, and a large pressing force is applied only to the upper surface thereof. As a result, only an upper surface (crushing surface) becomes an unstable shape (FIG. 7B). As in this embodiment, repeating the horizontal movement while gradually reducing the distance between the rotary roller 18 and the mounting table 16 can avoid these various problems.

As described above, the horizontal movement is repeated while gradually reducing the distance between the rotary roller 18 and the mounting table 16. Then, by repeating the reciprocation of about 10 to 15, the gold bumps 46 having the shape as shown in Fig. 3A are flatly shaped as shown in Fig. 3B.

In addition, during the reciprocating return, not only the vertical movement of the mounting table 16 but also the angle may be changed. That is, by changing the angle between the rotational roller 18 and the arrangement direction of the gold bump 46 at the time of return, this can be changed by rotating the mounting base 16 by the rotation mechanism at the time of return. By changing the angle with the arrangement | positioning direction of the rotating roller 18 in this way, it can prevent more that an crushed surface shape becomes an ellipse.

As described above, a state in which the rotary roller 18 and the mounting table 16 are relatively almost stopped is difficult to be established. As shown in FIG. 6 (A), the head of the gold bump 46 is formed of the mounting table 16. There is a case where it is pulled in the moving direction. This phenomenon occurs particularly remarkably when the amount of crushing is large, that is, when the vertical movement distance is large. At this time, the crushed surface of the gold bumps 46 tends to be elliptical as shown in Fig. 6B. In order to prevent such a problem, when the reciprocating movement is returned, the mounting table 16 is rotated, and the angle between the rotation roller 18 and the arrangement direction of the gold bumps 46 is changed at each horizontal movement. . Thereby, the gold bump 46 can be pressed in various directions, and it can prevent that it presses to elliptical shape.

As described above, according to the present embodiment, it is possible to easily flatten a large number of the gold bumps 46 arranged in a large area such as the wafer 40 easily.

As described above, according to the present invention, bump flattening can be advantageously performed on a substrate on which a plurality of bumps such as a wafer are formed.

Claims (11)

A mounting table for placing a substrate having a plurality of bumps arranged on an upper surface thereof, a rotating roller for pressing the head of the bump on the substrate to a lower end thereof; A roller drive mechanism for rotating the rotary roller, A horizontal moving mechanism for horizontally moving the mounting table relative to the rotating roller, Bump flattening device, characterized in that relatively close to the lower end of the rotary roller and the mounting table. The bump flattening device according to claim 1, further comprising a shank moving mechanism for moving the mounting table up and down relative to the rotating roller. The bump flattening device according to claim 1 or 2, wherein the direction of the rotation axis of the rotary roller is a direction intersecting with the arrangement direction of the bumps. 3. The bump flattening device according to claim 1 or 2, further comprising a rotating mechanism for rotating the mounting table in a horizontal plane relative to the rotating roller. A placing step of placing a substrate having a plurality of bumps arranged on an upper surface thereof on a mounting table; It has a pressurizing process of rotating the rotating roller pressurizing the head of the bump on the substrate to the lower end and at the same time moving the mounting table relative to the rotating roller, A bump flattening method, wherein in the pressing step, the lower end of the rotating roller and the mounting stand are relatively almost stopped. The bump flattening method according to claim 5, wherein in the pressing step, the direction of the rotation axis of the rotating roller is a direction intersecting with the arrangement direction of the bumps. 7. The bump flattening method according to claim 5 or 6, further comprising a plurality of pressurization processes having different horizontal moving directions. The first pressing step according to claim 5 or 6, wherein the first pressing step has a horizontal movement in the first horizontal movement direction, And a second pressing step having a horizontal movement in a second horizontal movement direction opposite to the first horizontal movement direction. 7. The bump flattening method according to claim 5 or 6, further comprising a plurality of pressurization steps having different distances between the mounting table and the lower end of the rotary roller. 7. The bump flattening method according to claim 5 or 6, further comprising a plurality of pressurization processes in which the arrangement direction of the bumps and the angle formed by the rotating roller are different. A bump bonding apparatus for bonding bumps to a plurality of electrodes on a substrate, further comprising: A mounting table for placing a substrate on which a plurality of bumps are arranged on the upper surface; A rotary roller for pressing the head of the bump on the substrate to the lower end; A roller drive mechanism for rotating the rotary roller, A horizontal moving mechanism for horizontally moving the mounting table relative to the rotating roller, Bump bonding apparatus characterized by relatively stopping the lower end and the mounting table of the rotary roller relatively.