JP4848162B2 - Apparatus and method for mounting conductive balls - Google Patents

Description

  The present invention relates to a stage for mounting a small conductive ball having a diameter of, for example, 1 mm or less at a predetermined position of a substrate and a ball filling apparatus using the same, and more particularly to a semiconductor device, an optical device, and an electronic circuit In addition, the present invention relates to a stage suitable for mounting conductive fine balls on a substrate when manufacturing a display device or the like, and a ball filling apparatus using the same.

Patent Document 1 discloses a bump forming apparatus that forms bumps on a semiconductor wafer or an electronic circuit board using conductive particles, and uses a mask having through holes of conductive particles at the bump forming positions. Has been.
JP 2002-151539 A

  In recent years, devices having electrodes, such as semiconductor devices, tend to have higher-density and miniaturized circuits to be mounted with increasing processing speed and multifunctionality. For this reason, in the process of manufacturing such a device, a substrate that is divided into one or a plurality of devices, such as a semiconductor wafer, or a substrate for electrode formation for transfer to the device, such as a semiconductor wafer, in order to form a large number of electrodes The conductive balls (conductive particles) mounted on the surface also tend to be minute. An example of a conductive ball currently being considered for mounting is a solder ball, a gold ball, or a copper ball having a diameter of about 30 to 300 μm.

  In a mask having a large number of openings (through holes) for arranging conductive balls on a substrate, the openings are not filled with a plurality of conductive balls as the diameter of the conductive balls to be arranged becomes smaller. It needs to be thin. As the mask becomes thinner, it becomes difficult to handle the mask. For example, if the mask is distorted when the mask is set on the substrate, a gap is formed between the mask and the substrate, and the conductive balls that enter the gap cause various problems. Conductive balls placed at a position shifted from the desired position on the substrate are not only unnecessary, but may be an obstacle to placing the conductive balls at a predetermined position or may cause a short circuit. There is sex. If a conductive ball is not placed at a predetermined position, it is sufficient to specify the position and add a conductive ball, while a conductive ball at an unnecessary position specifies its position. Not only is difficult, but it is also difficult to remove other conductive balls without affecting them.

One embodiment of the present invention is an apparatus for mounting a conductive ball on one surface of a substrate through a thin plate-shaped mask having a large number of openings, and the substrate supports the other surface of the substrate. A substrate support base having a support surface, a frame having an upper end surface located around the substrate support surface, a ball supply device for supplying conductive balls on the mask, and a mask between the substrate and the ball supply device And a mechanism for correcting the relative angle of the frame with respect to the substrate support so that the mask is in contact with the upper end surface and the mask is in contact with the surface of the substrate inside the upper end surface.

A mask (mask plate) in which the conductive balls to be arranged become minute and has a thin plate shape with a thickness of about 1 mm or less has low rigidity. By applying a large tension to the thin plate-like mask to improve the flatness, it is considered that a ball placement error that is considered to be caused by the mask distortion can be improved. However, according to observations by the inventors of the present application, it is difficult to improve an arrangement error, particularly an arrangement error in the edge of the substrate, that is, in the vicinity of the periphery of the substrate. On the other hand, by adopting the above-described apparatus , it is possible to improve an arrangement error at the edge of the substrate.

  The misplacement at the edge of the substrate is thought to be due to distortion of the mask at the edge of the substrate. Increasing the tension applied to the thin film or thin plate mask is not easy in terms of strength. Furthermore, it is not easy to prevent distortion even if the tension is increased. On the other hand, if it is acceptable to generate such a distortion in the mask, an arrangement error due to the distortion of the mask can be prevented.

The above apparatus is provided with an upper end surface that can move up and down relatively with respect to the substrate support surface around the substrate support surface that supports the substrate. For this reason, the positional relationship between the substrate support surface and the upper end surface is such that the upper end surface is in contact with the mask on the outer side with respect to one surface of the substrate set on the substrate support surface, and further, The difference between the upper and lower surfaces can be adjusted to such an extent that no significant distortion occurs in the mask. Therefore, there are tolerances in the substrate thickness depending on individual, lot, or type, and even if the mask setting, for example, a condition in which a slight difference occurs in the parallel state between the substrate and the mask, the mask is Touch the end face. For this reason, even if distortion occurs in the outer peripheral area of the mask, it is not the area on one side of the substrate, but the area on the upper end surface. Can be prevented. Accordingly, it is possible to prevent an arrangement error of the conductive balls due to mask distortion.

  Furthermore, since the thin plate-like mask itself has a small rigidity, it tends to deform following the minute irregularities. For this reason, even if there is a minute step between one surface of the substrate set on the substrate support surface and the top surface, the mask will follow and deform, so new distortion may occur in the mask. It is less likely to cause misplacement. Then, by providing a variable upper and lower upper surface around the substrate support surface, such conditions can be set for various substrates and masks.

The apparatus may include a stage including a substrate support (support) having a substrate support surface and a frame that is positioned around the substrate support surface and has an upper end surface . By moving the substrate support base and the frame relatively up and down, the vertical position of the upper end surface with respect to the substrate support surface can be changed. Furthermore, by providing a mechanism for moving the substrate support base and the frame relatively up and down, it is easy to change the vertical position of the upper end surface with respect to the substrate support surface. Such a mechanism uses, for example, an actuator such as a motor, and employs a mechanism in which the substrate support base protrudes and retracts in the vertical direction with respect to the frame, or the substrate support base and the frame are moved independently. it can.

  It is further preferable that the angle of the upper end surface with respect to the substrate support surface can be finely adjusted. As such a mechanism, there is a device that supports the frame at at least three points and moves it up and down.

It is preferable that the substrate support of the stage can support the substrate by suction. Since the distortion of the substrate itself can be corrected by closely supporting the substrate on the substrate support surface, it is possible to suppress an arrangement error of the conductive balls. In addition, the substrates on which the conductive balls are arranged include various substrates made of various materials such as semiconductor wafers, circuit substrates, and insulator substrates such as glass substrates. Can be set on the support surface.

One aspect of the apparatus of the present invention is a ball filling apparatus, the above-mentioned stage, a ball supply device for supplying a ball on the mask, a mask holding unit for holding the mask between the stage and the ball supply device, A moving mechanism for moving the stage and / or mask up and down is provided so that the stage and the mask are in contact with each other at the upper end surface.

  According to this ball filling device, the substrate is supported by the substrate support surface of the stage, and the mask is held by the mask holding unit provided between the stage and the ball supply device. Then, by contacting and supporting the mask on the upper end surface by the moving mechanism, it is possible to prevent the conductive ball disposed on the substrate from being affected by the distortion of the mask as described above. Therefore, under such conditions, by supplying the ball on the mask, while suppressing the occurrence of misplacement, by filling the ball in a plurality of openings provided in the mask, one side of the substrate A ball can be mounted at a predetermined position.

Furthermore, one form of the apparatus of the present invention is a ball mounting apparatus, which includes the ball filling apparatus and an alignment apparatus that positions the substrate held on the stage and the mask held on the mask holding portion.

  According to this ball mounting device, the alignment device positions the substrate held on the stage and the mask held on the mask holding unit, and then performs a series of operations on one surface of the substrate with the ball filling device. The ball can be mounted satisfactorily at a predetermined position.

  FIG. 1 is a plan view showing a schematic configuration of a ball mounting device (microball mounter) 1. FIG. 2 shows a schematic configuration of the ball mounting apparatus 1 in a side view. The ball mounting apparatus 1 is, for example, one surface of a wafer 10 having a planar circular semiconductor wafer 10 of about 8 inches (diameter 20 cm) or 12 inches (diameter 30 cm) as a substrate (workpiece). The fine ball B can be mounted (mounted) with high accuracy at a predetermined position on the upper surface 10a. As the ball B, for example, conductive fine balls (conductive fine particles) such as solder balls can be used.

  The ball mounting apparatus 1 is configured to warp the substrate 10 of the stage 40, the loader / unloader device 34 that loads / unloads the substrate 10 with respect to the stage 40, the pre-alignment unit 33, and the stage 40. A warp correction device 35 for correcting, a flux printing device 36 for applying a flux to the substrate 10, a ball filling device 20 for mounting a ball on the substrate 10 through a mask 11, and a stage 40 is transferred between these devices. And a stage transfer device 39. The ball mounting apparatus 1 moves the substrate 10 to the stage 40 after transferring the wafer 10 taken out by the supply stocker 31 to the pre-alignment unit 33 and correcting the θ axis of the substrate (wafer) 10. A series of correcting the warpage of the wafer 10, printing the flux at a predetermined position of the wafer 10, mounting the conductive ball B on the wafer 10, and storing the wafer 10 mounted with the conductive ball in the storage stocker 32. This process is fully automatic. Note that the pre-alignment unit 33 is provided with x-axis and y-axis tables, and also performs planar alignment of the wafer 10. By this alignment, the position mark of the wafer does not deviate from the field of view of the camera 28 (see FIG. 6).

  The ball filling apparatus 20 includes an alignment apparatus (see FIG. 6) 30 having a camera 28 for positioning the wafer 10 coated with the flux and the mask 11 held by the mask holding unit 50, and the positioned mask. 11 is provided with a conductive ball B, for example, a ball supply device 25 for supplying conductive microparticles on the order of micrometers. The wafer 10 to which the flux is applied is transferred to the filling device 20 by the stage transfer device 39 while being mounted on the stage 40.

  FIG. 3 is a plan view showing a schematic configuration of the stage 40. FIG. 4 shows a schematic configuration of the stage 40 in a sectional view. The stage 40 is a platform (platform) that supports the substrate 10. The stage 40 has a disk shape, and its upper surface 41 serves as a substrate support surface that supports the lower surface 10 b of the wafer 10, and the upper surface 42 serves as a substrate support. A frame 44 that is located around the surface 41, has an outer shape of approximately square, is in contact with the mask 11, and serves as an upper end surface that supports the mask 11 outside the wafer 10. Furthermore, the stage 40 supports the substrate support 43 and further has six actuators (first actuators) 46 provided at substantially equal intervals along the edge of the substrate support 43 so that it can be moved up and down. And four actuators (second actuators) 47 disposed at the four corners of the frame 44 so as to support the frame 44 and to move it up and down. These actuators 46 and 47 are each driven by one or a plurality of motors, and can be moved in conjunction or independently.

  Therefore, the stage 40 is a mask (mask plate) having a substrate support surface 41 that supports the lower surface 10b of the wafer 10 and a large number of openings 12 for mounting the conductive balls B at predetermined positions on the upper surface 10a of the wafer 10. ) 11 is supported on the periphery of the wafer 10, and the first actuator 46 and / or the second actuator 47 is driven as a moving mechanism, thereby being positioned around the substrate support surface 41. The upper end surface 42 to be moved can be moved up and down relatively with respect to the substrate support surface 41.

  The substrate support 43 has a disk shape that is substantially the same as or slightly different in size from the wafer 10, and can move up and down while supporting the wafer 10 within the frame 44. Further, the substrate support base 43 includes a plurality of holes 49 for supporting the wafer 10 on the substrate support surface 41 by suction. A negative pressure is applied to the substrate support surface 41 by an external vacuum generator through these suction holes 49, and the lower surface 10b of the wafer 10 is brought into close contact with the flatly processed substrate support surface 41, whereby the upper surface 10a of the wafer 10 is flattened. The degree can be improved. The mechanism for bringing the substrate 10 into close contact with the substrate support surface 41 is not limited to adsorption, and may be an electrostatic chuck or the like, and a plurality of mechanisms may be used in combination.

  Further, the stage 40 includes a mechanism 45 for attaching / detaching the wafer 10 to / from the substrate support surface 41. The attachment / detachment mechanism 45 has a pin 45a fixed thereto, and the substrate support surface 41 moves up and down with respect to the pin 45a. The attaching / detaching mechanism 45 may include a plurality of pins 45a that can protrude and retract in the vertical direction with respect to the substrate support surface 41, and a third actuator 48 that protrudes and retracts these pins 45a. The stage 40 is moved inside the mounter 1 by the transfer device 39 in a state where the wafer (substrate) 10 is held on the substrate support surface 41.

  5 and 6 show a process in which the wafer 10 is mounted on the stage 40 and the conductive balls B are arranged (mounted) at predetermined positions on the wafer 10.

  As shown in FIG. 5A, the wafer 10 taken out from the supply stocker 31 by the loader / unloader device 34 aligns the orientation flat or notch of the wafer 10 in the pre-alignment unit 33, and then the stage 40. Is carried to the substrate support surface 41 and set on the substrate support surface 41. As shown in FIG. 5B, the wafer 10 set on the substrate support surface 41 of the substrate support base 43 of the stage 40 is suction supported by the vacuum suction holes 49. The stage 40 first moves to the warp correction device 35. In the warpage correction apparatus 35, as shown in FIG. 5C, the warpage correction jig 35a presses the upper surface 10a of the wafer 10 toward the substrate support surface 41, whereby the lower surface 10b and the substrate support surface 41 of the wafer 10 are pressed. And the warpage of the substrate 10 is corrected. However, since the warpage of the wafer 10 almost returns to the initial warpage when the vacuum suction disappears, the deformation due to the warpage correction is temporary for the ball mounting process and is not permanent. Thereafter, the stage 40 moves to the flux printing device 36, and a predetermined pattern of flux is printed on the upper surface 10 a of the wafer 10.

  The stage 40 then moves to the ball filling device 20. In the filling apparatus 20, first, as shown in FIG. 6A, the position of the substrate support 43 is finely adjusted by the alignment apparatus 30 and supported by the wafer 10 supported by the stage 40 and the mask holder 50. Alignment with the mask 11 is performed. Next, as shown in FIG. 6B, the frame 44 is moved upward by the second actuator 47 so that the upper end surface 42 of the frame 44 contacts the lower surface 11 b of the mask 11. Subsequently, as shown in FIG. 6C, the substrate support 43 is moved upward by the first actuator 46, and the upper surface 10 a of the wafer 10 set on the substrate support surface 41 is aligned with the lower surface 11 b of the mask 11. .

  Since the mask 11 is fixed to the mask holding part 50, the value of the Z coordinate of the lower surface 11b of the mask 11 is known. Therefore, the movement amount of the second actuator 47 can be set so that the upper end surface 42 of the frame 44 moves to the value of the Z coordinate of the lower surface 11b of the mask 11 in advance. Similarly, the movement amount of the first actuator 46 can be set so that the upper surface 10a of the wafer 10 moves to the value of the Z coordinate of the lower surface 11b of the mask 11 in advance. Thereby, on the lower surface 11b of the mask 11, the upper surface 10a of the wafer 10 set on the substrate support surface 41 and the upper end surface 42 of the frame 44 can be made to coincide with each other. Theoretically, it can be set without any step. Therefore, in practice, there may be minute errors in various portions, but the step between the upper surface 10a and the upper end surface 42 of the wafer 10 can be set to a minute step that does not cause a problem.

  In the ball filling device 20, the conductive ball B is supplied to the upper surface 11 a of the mask 11 by the ball supply device 25 in the state of FIG. The conductive ball B is filled in the plurality of openings 12 of the mask 11 set on the upper surface 10 a of the wafer 10, and the conductive ball B can be arranged at a predetermined position on the wafer 10. The ball supply device 25 of the filling device 20 of the present example includes a rotary head 25a, and the head 25a moves while rotating the surface 11a of the mask 11 while holding a large number of balls B below the head 25a. To do. Accordingly, the ball B is sequentially transferred into the multiple openings 12 of the mask 11 along the trajectory of the head 25 a and is disposed at a predetermined position on the wafer 10. Thereafter, the wafer 10 on which the ball B is mounted is lowered together with the frame 44 while being sucked and held by the substrate support base 43, and the stage 40 is transferred to the removal position of the wafer 10, that is, the loader / unloader device 34. . Then, after the vacuum suction of the wafer 10 by the substrate support table 43 is completed, the substrate support table 43 is lowered to support the wafer 10 with the push-up pins 45a, and the wafer 10 on which the ball B is mounted is attached to the substrate support table 43. Then, it is transported to the storage stocker 32. Thus, the process of mounting the ball B on the upper surface 10a of the wafer 10 is completed.

  As described above, in the ball filling apparatus 20, the conductive ball B is mounted on the one surface 10 a of the substrate 10 through the thin plate-like mask 11 having a large number of openings 12. At this time, the other surface 10 b of the substrate 10 is supported by the substrate support surface 41, is located around the substrate support surface 41, and the mask 11 is supported by an upper end surface 42 that is variable up and down with respect to the substrate support surface 41. ing. The edge (periphery) of the mask 11 is pulled by the mask holding part 50 and is set in a substantially horizontal state as a whole. Further, in the vicinity of the wafer 10, the mask 11 is first supported in contact with the upper end surface 42 of the frame 44, and is in contact with the surface 10 a of the wafer 10 inside thereof. When the surface is pressed against the thin mask 11 from below, the mask 11 is likely to be distorted or bent around the surface pressed from below. By adopting this stage 40, such distortion or deflection occurs in a region in contact with the upper end surface 42 of the mask 11, and does not affect the upper surface 10a of the substrate 10. Therefore, it is possible to prevent an arrangement error of the ball B.

  FIG. 7 shows a state where the mask 11 is placed on the upper surface 10 a of the wafer 10 and the upper end surface 42 of the frame 44. FIG. 8 shows the periphery of the wafer 10 in an enlarged manner. FIG. 9 shows a state where the upper surface 10 a of the wafer 10 mounted on the substrate support base 43 is in contact with the mask 11 without placing the frame on the mask 11. Further, FIG. 10 shows an enlarged view of the periphery of the wafer 10 at that time. As described above, when the gap S is generated between the surface 10a of the wafer 10 and the mask 11, the ball B may enter the gap S and various arrangement errors may occur. As shown in FIG. 9 and FIG. 10, when the wafer 10 is set directly on the thin plate-shaped mask 11, the mask 11 is likely to be distorted at the edge of the wafer 10, and between the mask 11 and the wafer 10. A gap S is created, and an error occurs in the arrangement of the balls B. The mask 11 is accurately adjusted so as to be parallel to the front surface 10a of the wafer 10 mounted on the substrate support 43, and the front surface 10a of the wafer is in close contact with the back surface 11b of the mask 11, or the back surface of the mask 11 Even if the position of the mask 11 and the wafer 10 is controlled so that the distance between the surface 11a and the surface 10a of the wafer is such that the ball B does not escape, the ball supply device transfers the ball B to the peripheral portion of the wafer 10. The phenomenon that the gap S is generated around the wafer 10 and the mask 11 seems to be unavoidable, for example, when a part of the wafer 10 moves to the outside of the wafer 10.

  As shown in FIG. 7, the stage 40 has a frame 44 that moves up and down, and an upper end surface 42 of the frame 44 can be in contact with the mask 11 outside the surface 10 a of the wafer 10. At the portion where the upper end surface 42 of the frame 44 is in contact with the mask 11, the mask 11 may be distorted or bent around it, and a gap S may be generated between the upper end surface 42 and the mask 11. There is. However, in the region of the surface 10a of the wafer 10 inside the upper end surface 42, it is possible to prevent a significant gap that may cause an arrangement error between the mask 11 and the surface 10a of the wafer 10 from occurring. The reason is that the upper end surface 42 and the surface 10 a of the wafer 10 are set to be basically the same height by the actuators 46 and 47, and the upper end surface 42 and the substrate surface 10 a with respect to the mask 11. Is considered to be handled as almost one plane.

  Therefore, by mounting the ball B on the surface 10a of the wafer 10 using the filling device 20, it is possible to prevent the misplacement of the ball B that easily occurs in the vicinity of the outer periphery of the wafer 10, and to improve the yield of the wafer on which the ball B is mounted. It can be improved. The frame 44 is preferably adjusted so that the upper end surface 42 of the frame 44 is in contact with the mask 11 around the wafer 10. By independently driving the four second actuators 47 provided on the frame 44, the inclination of the frame 44 with respect to the horizontal direction can be finely adjusted. Therefore, not only the thickness of the wafer 10 set on the substrate support surface 41 but also the height of the frame 44 corresponding to the angle of the surface 10a and the angle of the mask 11 (the lower surface 11b of the mask 11) in the Z-axis direction. The angle can be corrected.

  In FIG. 6, the frame 44 is raised first, but the substrate support base 43 is raised first or the substrate support surface 41 and the upper end surface 42 are aligned so that there is no step, It is also possible to rise together. The conductive ball B mounted on the wafer 10 is not limited to a solder ball, and may be a conductive ball such as gold or copper. Further, for example, a conductive coating such as a resin ball coated with solder is applied. It may be a ball. The above configuration is considered to be effective for all apparatuses that mount conductive balls on a substrate through a mask. In particular, a mask for setting fine or miniaturized conductive particles becomes thin, and the above gap is likely to occur around the substrate. Therefore, the present invention is effective as a technique for handling a minute ball, for example, a ball having a diameter of 1 mm or less, or about several tens to several hundreds of μm.

  In the stage 40 of this example, the vertical position of the substrate support 43 having the substrate support surface 41 can be changed by the first actuator 46, and the upper and lower positions of the frame 44 having the upper end surface 42 can be changed by the second actuator 47. The position can be changed. Instead, the stage includes a mechanism for moving the upper end surface 42 and the substrate support surface 41 up and down simultaneously and a mechanism for moving the upper end surface 42 up and down relatively with respect to the substrate support surface 41. Also good. Further, the shape and size of the substrate support base 43 or the substrate support surface 41 can be changed to a polygon depending on the shape of a substrate such as a wafer or a circuit board to be mounted thereon. The shape of the frame 44 can also be changed.

The top view which shows an example of a ball mounting apparatus. The side view which shows the ball | bowl mounting apparatus of FIG. The top view which shows an example of a stage. Sectional drawing cut | disconnected and shown along the IV-IV line in FIG. (A)-(c) is a figure explaining the process of mounting a ball | bowl on a wafer. (A)-(d) is a figure explaining the process in which a ball | bowl is mounted on a wafer following FIG. The figure which shows the state which set the mask to the upper surface of a wafer and the upper end surface of a flame | frame in the stage of FIG. The figure which expands and shows the area | region enclosed by VIII in FIG. The figure which shows the state which set the mask on the upper surface of a board | substrate, without using a flame | frame. The figure which expands and shows the area | region enclosed by X in FIG.

Explanation of symbols

1 Ball mounting device, 10 Wafer (substrate)
10a Upper surface of wafer (one surface of substrate)
10b Lower surface of wafer (the other surface of the substrate)
DESCRIPTION OF SYMBOLS 11 Mask, 12 Mask opening 20 Ball filling device, 30 Alignment device 25 Ball supply device, 40 Stage 41 Substrate support surface, 42 Upper end surface 43 Substrate support (support), 44 Frame 49 Movement mechanism, 50 Mask holding part B ball

Claims (7)

An apparatus for mounting a conductive ball on one surface of a substrate through a thin plate-like mask having a large number of openings,
A substrate support with a substrate support surface for supporting the other surface of the substrate;
A frame having an upper end surface located around the substrate support surface;
A ball supply device for supplying conductive balls onto the mask;
A mask holding unit for holding the mask between the substrate and the ball supply device;
And a mechanism for correcting a relative angle of the frame with respect to the substrate support so that the mask is in contact with the upper end surface and the mask is in contact with the surface of the substrate inside the upper end surface. In claim 1,
Having a stage including the substrate support and the frame;
The stage further includes a first and a moving device for moving the substrate support table up and down, looking contains a plurality of second moving device moving the four corners of the frame up and down, respectively, a mechanism for correcting the angle including the first mobile device and the plurality of second mobile devices, device. According to claim 2, wherein the plurality of second mobile device can correct the Z-axis direction of the height of the frame, device.   4. The apparatus according to claim 1, wherein the substrate support base is capable of sucking and supporting the substrate. In claim 2 or 3,
An apparatus further comprising an alignment device that positions the substrate supported by the stage and the mask held by the mask holding unit. A stage for supporting the substrate in order to mount the conductive ball on one surface of the substrate through a thin plate-like mask having a large number of openings;
A substrate support with a substrate support surface for supporting the other surface of the substrate;
A frame having an upper end surface located around the substrate support surface;
A first moving device for moving the substrate support up and down;
A plurality of second moving devices that move up and down each of the four corners of the frame;
The stage, wherein the plurality of second moving devices can correct the height and angle of the frame in the Z-axis direction with respect to the substrate support . A method of mounting a conductive ball on one surface of a substrate through a thin plate-shaped mask having a large number of openings,
Supporting the other surface of the substrate by a substrate support surface;
An upper end surface positioned around the substrate support surface and movable up and down with respect to the substrate support surface is in contact with and supported by the mask, and an angle of the upper end surface with respect to the substrate support surface is corrected . Contacting the mask with the surface of the substrate on the inside;
Supplying a conductive ball onto the mask and filling the opening in the mask with the ball.

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