JPH05299425A - Ball bump bonder - Google Patents

Abstract

PURPOSE:To provide a ball bump bonder which forms a bump electrode on a semiconductor wafer with good adhesion by metal ball ultrasonic wave bonding. CONSTITUTION:A stage 3 for sucking a semiconductor wafer 1 by vacuum is provided with a pressing member 4 which partially presses an outer peripheral part 1a of the semiconductor wafer 1 which is a defective pellet region of the semiconductor wafer 1. The pressing member 4 stored in a recessed section 5 formed on the upper surface of the stage 3 is lifted by means of a driving shaft 8 and is rotated horizontally to be moved to the outer peripheral part 1a of the semiconductor wafer 1 from the recessed section 5 and then it is lowered to press the outer peripheral part 1a. With that condition maintained, a metal ball 6 is ultrasonic-bonded onto the semiconductor wafer 1 by means of a capillary 11 of a ball bonding equipment 7 to form a bump electrode 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball bump bonder for bonding metal balls on a semiconductor wafer to form bump electrodes.

[0002]

2. Description of the Related Art In a TAB type semiconductor device, leads of a TAB tape are connected to bump electrodes on the surface of a semiconductor pellet. In the manufacture of this type of semiconductor device, the bump electrodes are formed on the semiconductor pellets in the state of a semiconductor wafer having a plurality of semiconductor pellets formed thereon.

The bump electrodes are formed by a plating method or a ball bonding method. The former plating method can form a large number of bump electrodes at one time, but it is difficult to control the height and diameter of the bump electrodes to be constant, and the yield is low for forming bump electrodes having a small diameter and high height. The latter ball bonding method uses one metal ball on the semiconductor wafer.
Since the bump electrodes are formed by metal balls by ultrasonic bonding, the shape of the bump electrodes is stable and the yield is good.

FIG. 5 shows a conventional ball bump bonder in which bump electrodes (2) are formed on the surface of a semiconductor wafer (1) by a ball bonding method, which will be described.

The horizontal stage (3) has a large number of vacuum suction holes (9) on a flat upper surface, and each vacuum suction hole (9) is connected to a vacuum pump (13). The semiconductor wafer (1) is loaded onto the stage (3) from the outside, and the semiconductor wafer (1) is positioned and supported on the central portion of the stage (3) by vacuum suction.

An arm (10) of the ball bonding device (7) is arranged above the stage (3) so as to be vertically movable. A capillary (11) is fixed vertically to the tip of the arm (10). A metal ball (6) projects from the lower end of the capillary (11). The metal ball (6) has a capillary (1
It is a metal block in which the tip of the wire (12) inserted in 1) is melted with a hydrogen torch.

When the semiconductor wafer (1) is vacuum-adsorbed on the stage (3), the arm (10) is driven to move the capillary (11) to one electrode pad in one semiconductor pellet region of the semiconductor wafer (1) [Fig. (Not shown). The metal ball (6) is pressed against the electrode pad by the tip of the lowered capillary (11), ultrasonic vibration is applied to the metal ball (6) by the capillary (11), and the metal ball (6) is ultrasonically applied to the electrode pad. Bond.

After this bonding, the wire (12) is cut from the metal ball (6), and the bump electrode (2) of the metal ball (6) is formed on the electrode pad. Capillary (1
The metal ball (6) is formed again at the tip of (1), the capillary (11) moves onto the next electrode pad of the semiconductor wafer (1), and the above operation is repeated.

[0009]

The flat top surface of the stage (3) and the back surface of the semiconductor wafer (1) that is vacuum-adsorbed on the top surface have a variation in the adhesion state, and the semiconductor wafer (1) is warped. Then, the suction force of the semiconductor wafer (1) on the stage (3) varies. Therefore, the semiconductor wafer (1) vibrates laterally on the stage (3) by the ultrasonic vibration applied when the metal ball (6) is ultrasonically bonded to the semiconductor wafer (1) by the capillary (11). It was sometimes misaligned.

When the semiconductor wafer (1) laterally vibrates on the stage (3) in this way, a part of the ultrasonic energy applied to the metal ball (6) by the capillary (11)
It is absorbed by the lateral vibration of the semiconductor wafer (1). As a result, the ultrasonic vibration transmission efficiency at the time of ball bonding may be reduced, the mechanical adhesive force of the bump electrodes (2) formed on the semiconductor wafer (1) may be reduced, and the electrical connectivity may be deteriorated. It was

When the semiconductor wafer (1) is laterally displaced on the stage (3), the position at which the metal ball (6) is bonded next to the semiconductor wafer (1) is displaced, which is a troublesome process for correcting the position. There was a problem that various work processes and equipment were required.

It is an object of the present invention to provide a ball bump bonder which increases the supporting strength of a semiconductor wafer by a stage and always ultrasonically bonds a metal ball to the semiconductor wafer in good condition.

[0013]

According to the present invention, a semiconductor wafer is vacuum-sucked on a horizontal stage, and a metal ball is ultrasonically bonded to a predetermined position on the surface of the semiconductor wafer by a capillary of a ball bonding apparatus. The bump bonder achieves the above object by adding a pressing member that partially presses the peripheral portion of the surface of the semiconductor wafer on the stage to the stage and reinforces the semiconductor wafer support by the stage. ..

Further, in the present invention, a concave portion for accommodating the pressing member is provided around the semiconductor wafer mounting portion of the flat upper surface of the stage, and the standby position for accommodating the pressing member in the concave portion of the stage and the concave portion It is desirable for the handling of the pressing member to be advantageous in that it is reciprocally moved to and from the wafer pressing position where it projects and presses on the peripheral edge of the semiconductor wafer.

[0015]

The semiconductor wafer is firmly fixed on the stage by pressing the peripheral edge of the semiconductor wafer vacuum-adsorbed on the stage to the stage by the pressing member, and the lateral vibration of the semiconductor wafer at the time of ultrasonic bonding of metal balls, No lateral slippage. The semiconductor pellet region on the peripheral portion of the semiconductor wafer pressed by the pressing member is originally a defective pellet region, and even if the pressing member is pressed on this peripheral portion, there is no risk of causing defective pellets.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described below with reference to FIGS. The same or corresponding parts as those in FIG. 5 of the embodiment shown in FIG.

In the embodiment shown in FIGS. 1 (a) and 1 (b), a pressing member (4) attached to the stage (3) is used to move the peripheral edge portion (1a) of the semiconductor wafer (1) to the stage (3). It is characterized by pressing appropriately. The semiconductor wafer (1) is vacuum-sucked by the stage (3), pressed by the pressing member (4), and positioned and mounted on the stage (3) with stable strength. Metal balls (6) are ultrasonically bonded on the semiconductor wafer (1) by a ball bonding device (7).

A semiconductor wafer (1) on the stage (3)
Are carried in and vacuum-adsorbed as in the conventional case. A plurality of semiconductor pellets are formed on this semiconductor wafer (1). Normally, the semiconductor pellet formed on the peripheral edge portion (1a) of the semiconductor wafer (1) has a high probability of being defective in manufacturing, and the peripheral edge portion (1a) is originally formed as a defective pellet region. Such a peripheral part (1a)
1 is roughly divided into three regions, that is, a portion opposite to the orientation flat (1b) of the semiconductor wafer (1) and both sides of the orientation flat (1b), as shown by the hatched portion in FIG.

Therefore, three pressing members (4) are attached to the stage (3) so as to correspond to the above-mentioned three peripheral portions (1a) of the semiconductor wafer (1). The three pressing members (4) may have the same structure, and specific examples thereof are shown in FIGS. 2 and 3.

The pressing member (4) is movably arranged on the stage (3) so that the pressing member (4) does not interfere with the loading / unloading operation of the semiconductor wafer (1) with respect to the stage (3).

For example, recesses (5) for accommodating the pressing member (4) are formed at three locations around the semiconductor wafer mounting portion at the center of the upper surface of the stage (3). The drive shaft (8) is vertically passed through one end of the bottom of the recess (5), and one end of the pressing member (4) is fixed to the tip thereof.

The drive shaft (8) is installed on the stage (3) so as to be vertically movable and rotatable, and causes the pressing member (4) to vertically rotate as shown by solid line arrows and broken line arrows in FIG. That is, the pressing member (4) has a standby position which is accommodated in the recess (5) and a pressing position where the peripheral part (1a) of the semiconductor wafer (1) is pressed by rising, rotating and descending from the recess (5). Move back and forth between.

Next, an operation example of the ball bump bonder using the pressing member (4) will be described.

Until the semiconductor wafer (1) is loaded into the stage (3), the pressing member (4) is housed in the recess (5) of the stage (3) as shown in FIG. At this time, the upper surfaces of the pressing member (4) and the stage (3) are substantially flush with each other. By doing so, the entire upper surface of the stage (3) becomes flat, and the semiconductor wafer (1) is smoothly carried onto the stage (3) without being disturbed by the pressing member (4).

When the semiconductor wafer (1) is positioned on the stage (3) and is vacuum-sucked, the drive shaft (8) rises, and the pressing member (4) is recessed (as shown by the chain line in FIG. 4). Project from 5) to the specified height. Next, the drive shaft (8) is rotated laterally about 90 °, and the tip of the pressing member (4) is moved to the peripheral edge (1a) of the semiconductor wafer (1) as shown by the chain line in FIG.
Located directly above. After this rotation, the drive shaft (8) descends, and the tip of the pressing member (4) presses the peripheral edge (1a) of the semiconductor wafer (1) against the stage (3).

As shown by the solid line in FIG. 3, the pressing member (4)
An elastic protrusion (4 ') such as silicon rubber is fixed on the lower surface of the tip of the semiconductor wafer (1) with the elastic protrusion (4').
The peripheral edge (1a) of the is pressed. In addition, when the upper and lower edges of the outer periphery of the semiconductor wafer (1) are chamfered to prevent cracking and chipping, the elastic protrusions (4 ') of the pressing member (4) are located at locations away from the chamfered portion (1c). Try to hit Further, the corresponding pressing members (4) press the respective centers of the three peripheral portions (1a) of the semiconductor wafer (1).

By pressing the three points on the peripheral edge portion (1a) of the semiconductor wafer (1) with the pressing member (4) as described above, the peripheral edge portion (1a) is damaged by the pressing member (4) or the pressing member (4) is pressed. There is no need to worry about cracking or chipping by pressing (4). In addition, since the pellet region of the peripheral edge portion (1a) is originally disposed as a defective pellet region, there is no problem even if the peripheral edge portion (1a) is slightly damaged by the pressing member (4).

The semiconductor wafer (1) on the stage (3) is pressed on the stage (3) by pressing three points on the peripheral edge (1a) of the semiconductor wafer (1) vacuum-adsorbed on the stage (3) by the pressing member (4). ), The supporting strength is increased. Therefore, even when ultrasonic vibration is applied to the semiconductor wafer (1) when ultrasonically bonding the metal ball (6) to the semiconductor wafer (1) by the capillary (11) of the ball bonding device (7), the semiconductor wafer ( In 1), ball bonding is performed well without lateral vibration or lateral displacement.

The semiconductor wafer (1) is pressed against the stage (3) by the pressing member (4), and ball bonding is sequentially performed on the electrode pads at a plurality of locations on the semiconductor wafer (1) to form bump electrodes (2). ) Is formed.

After all ball bonding is completed,
The pressing member (4) operates in the opposite manner to the above operation, is separated from the semiconductor wafer (1), and is housed in the recess (5) of the stage (3). Then, the vacuum suction of the stage (3) is released, and the semiconductor wafer (1) is unloaded from the stage (3). At this time as well, since the pressing member (4) is housed in the recess (5), it does not interfere with the work of unloading the semiconductor wafer (1).

The present invention is not limited to the above embodiment, and for example, the pressing member for pressing the peripheral edge of the semiconductor wafer vacuum-adsorbed on the stage is separate from the stage and is located on the stage and at a place apart from the stage. It may move back and forth.

[0032]

According to the present invention, the semiconductor wafer is firmly fixed on the stage by the vacuum suction force of the stage and the pressing force of the pressing member. There is an effect that the ultrasonic vibration transmission efficiency of the metal ball is improved and the adhesive force and electrical connectivity of the bump electrode to the semiconductor wafer are improved as a result. Further, since there is no concern about lateral displacement of the semiconductor wafer on the stage, the step of correcting the position of the semiconductor wafer during ball bonding can be omitted, and the man-hours for ball bump bonding and the equipment can be reduced.

Further, since the semiconductor pellet region on the peripheral portion of the semiconductor wafer which is pressed by the pressing member is originally a defective pellet region, there is no fear of causing defective pellets even if the pressing member is pressed on this peripheral portion. The pressing work of the semiconductor wafer by the pressing member becomes simple.

[Brief description of drawings]

FIG. 1 is a diagram showing a ball bump bonder according to an embodiment of the present invention, in which (a) is a side view including a partial cross section and (b) is a plan view.

FIG. 2 is an enlarged perspective view of a pressing member of the ball bump bonder of FIG. 1 and its surroundings.

FIG. 3 is an enlarged sectional view taken along the line AA of FIG.

FIG. 4 is a sectional view of the portion of FIG. 3 during a standby operation of the pressing member.

FIG. 5 is a side view including a partial cross section of a conventional ball bump bonder.

[Explanation of symbols]

 1 Semiconductor wafer 2 Bump electrode 3 Stage 4 Pressing member 5 Recess 6 Metal ball 7 Ball bonding machine

Claims (2)

[Claims] 1. A horizontal stage for vacuum-suctioning and positioning and supporting a semiconductor wafer, a pressing member for partially pressing the peripheral edge of the surface of the semiconductor wafer on the stage, and a pressing member for vacuum-sucking on the stage. A ball bump bonder, comprising: a ball bonding device for ultrasonically bonding a metal ball to a bump electrode to form a bump electrode at a predetermined position on the surface of a semiconductor wafer which has been pressure-reinforced. 2. The stage has a recessed portion around a semiconductor wafer mounting portion on a flat upper surface, and the pressing member has a standby position accommodated in the recessed portion of the stage and a peripheral edge of the semiconductor wafer protruding from the recessed portion. 2. The ball bump bonder according to claim 1, wherein the ball bump bonder reciprocates between a wafer pressing position that presses the top of the part.