JP2014056980A - Die bonder and bonding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a die bonder in which reliability is improved by automatically measuring a falling amount of a bonding head or the like, and a bonding method.SOLUTION: The die bonder comprises: a collet which adsorbs a die; a processing head which includes the collet in the distal end thereof and performs at least either adsorption processing for adsorbing the die and bonding processing for bonding the die to a work; a measuring plate which includes a parallel surface parallel with a bonding surface for performing bonding; adsorption flow rate measuring means which measures an adsorption flow rate while the die is not retained; lifting means which lifts the processing head; and a control section in which the processing head that is not retaining the die is lifted with respect to the measuring plate, a lift position of the processing head in the case where the adsorption flow rate of the processing head is spread over an adsorption threshold flow rate that is a predetermined adsorption flow rate, is defined as an offset amount and based on the offset amount, a falling amount of the processing head during the processing is calculated.

Description

  The present invention relates to a die bonder and a bonding method, and more particularly to a highly reliable die bonder and a bonding method.

  Part of the process of assembling a package by mounting a die (semiconductor chip) (hereinafter simply referred to as a die) on a substrate such as a wiring board or a lead frame, or a workpiece such as a die already stacked on the substrate, Hereinafter, there are a process of dividing a die from a wafer) and a bonding process of mounting the divided die on a substrate.

  In the bonding process, dies separated from the wafer are separated from the dicing tape one by one, and bonded onto the substrate using a suction tool called a collet (suction nozzle).

  As a conventional technique for performing the bonding process, for example, there is a technique described in Patent Document 1. Patent Document 1 discloses a technique of a bonding head having a structure in which a collet follows the surface of a die.

JP 2009-253060 A

  In recent years, die thinning has been promoted for the purpose of promoting high-density mounting of semiconductor devices. As die thinning progresses, if the amount of descent of the bonding head, etc. is not correctly grasped, adverse effects such as not reaching the target position or damaging the die when the die is picked up, mounted on the substrate, etc. The possibility of giving out comes out.

  The variation in the amount of descent of the bonding head or the like is particularly affected by the height variation during the manufacture of the collet. As the die becomes thinner, variations in height during collet manufacturing greatly contribute to the adverse effects. In addition, it is necessary to replace the collet with diversification of die (die size), or to increase the frequency of collet contact with the die surface in order to prevent scratches and contamination of the die surface as the speed increases. is there.

  Accordingly, an object of the present invention is to provide a die bonder and a bonding method with high reliability by automatically measuring the amount of descent of a bonding head or the like.

In order to achieve the above object, the present invention has at least the following features.
The present invention relates to a collet that adsorbs a die, a processing head that includes the collet at the tip and performs at least one of an adsorbing process that adsorbs the die and a bonding process that bonds the die to a workpiece, and the bonding A measuring flat plate having a parallel surface parallel to the bonding surface, an adsorption flow rate measuring means for measuring an adsorption flow rate when the die is not held, an elevating means for raising and lowering the processing head, and holding the die The processing head is moved up and down with respect to the measurement flat plate, and the lifting position of the processing head when the suction flow rate of the processing head crosses the suction threshold flow rate that is a predetermined suction flow rate is set as an offset amount. And a control unit that obtains a descent amount of the processing head during the processing based on the amount.

  Further, the present invention is a processing step for performing at least one of a suction step for sucking a die with a collet, a processing for sucking the die with a processing head including a tip collet, and a processing for bonding the die to a workpiece, An elevating step for elevating and lowering a processing head not holding the die with respect to a measurement flat plate having a parallel plane parallel to the bonding surface to be bonded, and an adsorption flow rate for measuring the adsorption flow rate of the processing head during the elevating The measurement step and the ascending / descending position of the processing head when the adsorption flow rate crosses the adsorption threshold flow rate, which is a predetermined adsorption flow rate, is set as an offset amount, and the descent amount of the processing head during the processing based on the offset amount And a step of obtaining a descent amount for obtaining.

Furthermore, the processing head is lowered from the measurement flat plate to a predetermined position at a high speed having at least a speed equal to or higher than that during the processing, and then based on an allowable distance that is a distance from the measurement flat plate at the adsorption threshold flow rate. You may lower it in units.
In the present invention, the step unit may be lowered in small step units smaller than the allowable distance.

Further, according to the present invention, the step unit is made larger than the permissible distance and lowered in units of large steps, and after the adsorption flow rate crosses the adsorption threshold flow rate due to the lowering of the processing head, the step unit is made smaller than the permissible distance. It may be increased in small steps.
In the present invention, the small step may be a control resolution of a motor that moves the processing head up and down.

  Further, according to the present invention, the processing head includes a bonding head that sucks the die from a wafer and bonds the die to the workpiece, or a pickup head that sucks the die from the wafer and places the die on a pre-alignment stage; It may be a bonding head that picks up the die placed on the alignment stage and bonds it to the workpiece.

  Therefore, according to the present invention, a descent amount of the bonding head or the like can be automatically measured, and a highly reliable die bonder and bonding method can be provided.

It is a figure showing the schematic diagram of die bonder 100 which is a 1st embodiment of the present invention. It is a figure which shows the block for the structure of the bonding head 31, and raising / lowering of a bonding head, and adsorption | suction control of the die | dye D. FIG. It is a figure which shows the relationship between adsorption | suction flow volume and the fall amount of a collet, especially the relationship between adsorption | suction threshold flow volume and allowable distance. It is a figure which shows the 1st Example which defines the descent | fall amount of a bonding head. It is a figure which shows the 2nd Example which defines the descent | fall amount of a bonding head. It is the conceptual diagram which looked at the die bonder which is the 2nd Embodiment of this invention from the top. It is a figure which shows the bonding flow of die | dye in Embodiment 1,2.

(Embodiment 1)
FIG. 1 is a schematic view of a die bonder 100 according to the first embodiment of the present invention. FIG. 1A is a top view of the die bonder 100, and FIG. 1B is a front view as viewed from the arrow A in FIG.
The die bonder 100 is roughly divided into a die supply unit 1, a pickup unit 2, a pre-alignment unit 3, a bonding unit 4, a substrate supply unit 6, a substrate carry-out unit 7, a transport unit 5, and operations of the respective units. And a control unit 8 for monitoring and controlling.

  First, the die supply unit 1 will be described. The wafer holding table 12 is fixed to the four sides of the wafer holding stage 14 (see FIG. 1A). The wafer holding stage 14 is moved in the X and Y directions by the XY driving unit 15 provided on the holding unit base 17 shown in FIG. 1B, and is further moved by the rotation driving unit 16 provided on the XY driving unit 15. It is provided to rotate. On the other hand, the push-up unit 13 is fixed at a predetermined position of the holding unit base 17 and pushes up the die D of the wafer 11 selected by the rotation drive unit 16.

  The pickup unit 2 includes a pickup head 21 that picks up and picks up the die pushed up by the pushing-up unit 13, an X drive shaft 22 that moves the pickup head 21 in the X direction, and an alignment mark (not shown) of the wafer 11. ) And a wafer recognition camera 23 (see FIG. 1B) for recognizing the position of the die D to be picked up. The pickup head 21 reciprocates between the push-up position of the die D and the prestage 31 by the X drive shaft 22 and arranges four dies on the prestage 31 in a row in the longitudinal (Y) direction of the prestage.

The bonding unit 4 picks up the die D from the prestage 31 and bonds it to the substrate P that has been transported, a component recognition camera 42 that images the holding state of the die D of the bonding head 41, and a plurality of ( The Y drive shaft 43 that moves the four bonding heads 41 in the Y direction and the position recognition mark (not shown) of the substrate P that has been transported are imaged to determine the bonding position of the die D to be bonded. A substrate recognition camera 44 for recognition. In addition to the Y drive shaft 43, each bonding head 41 has a Z drive shaft 47 for raising and lowering a collet (also referred to as a suction nozzle) 60 provided at the tip, as shown in FIG.
With such a configuration, the bonding head 41 picks up the die D from the prestage 31, images the holding state of the die D by the component recognition camera 42 while moving along the Y drive axis, and bonds based on the result. The die D is bonded to the substrate P by correcting the position / posture. This operation is performed on four dies on the prestage 31 simultaneously or individually.

The pre-alignment unit 3 has a pre-stage 31 on which the die D picked up by the pickup head 21 is placed, a fixing plate 32 that fixes the pre-stage 31, and the upper and lower sides of the paper surface of FIG. A Y drive shaft (prestage horizontal moving means) 33 that moves in the Y direction, an X drive shaft 34 that moves the fixed plate 32 in the left and right (X) directions of FIG. 1A, and a prestage 31 of the die D And a mounting component recognition camera 35 that images the mounting state of the camera.
With this configuration, the pre-alignment unit 3 moves the prestage 31 in the X, Y, and Z directions in cooperation with the movement of the pickup head 21 and the bonding head 41 so that the operations of the pickup head and the bonding head are minimized. To do.

  In such a die bonder, it is necessary to replace the collet according to the type (die size), or to increase the frequency of replacing the collet in contact with the die surface in order to prevent scratches and contamination on the die surface. is there. For this purpose, the pickup unit 2 and the bonding 4 are provided with replacement nozzle stockers 24 and 45, respectively.

  The transfer unit 5 includes a substrate transfer pallet 51 on which one or a plurality of substrates (four in FIG. 1) are placed, and pallet rails 52 on which the substrate transfer pallet 51 moves. Two transport units are provided in parallel.

  With such a configuration, the substrate transport pallet 51 has the substrate placed on the substrate supply unit 6, moves to the bonding position along the pallet rail 52, moves to the substrate unloading unit 7 after bonding, and moves to the substrate unloading unit 7. Pass the board. The first and second transport units are driven independently of each other.

  FIG. 2 is a diagram showing the configuration of the bonding head 31 and the blocks for controlling the raising and lowering of the bonding head and the suction of the die D. Since the pickup head 21 and the bonding head 41 have the same structure, the bonding head 41 will be described as a representative here. The following description will be given by the bonding head 41 as a representative.

  The bonding 41 includes a collet holder 61 that holds the collet 60 and can exchange the collet when necessary. The bonding head 41, the collet holder 61 and the collet 60 have suction holes 60v, 61v and 41v communicating with each other for sucking and holding the die D. The suction hole 41v of the bonding head 41 communicates with the suction equipment 20 provided outside, and is connected to the pump PO via the flow rate sensor RS.

  The control device 8 shown in FIG. 1 includes a control unit 8C that controls the bonding head 41, a memory 8M that stores a control program, data, and the like necessary for control, and a Z drive shaft 47 of the bonding head 41. A driver 47D and a motor 47M are provided. The control unit 8C drives the driver 47D with data and position information obtained in advance. The motor 43M may be a pulse motor or a servo motor. FIG. 2 shows only one configuration because the configuration of each bonding head 41 is the same.

  With the above configuration, the die bonder 100 picks up the die D from the wafer 11 with the pickup head 21 and places it on the prestage 31, and then picks up the die from the prestage with the bonding head 41 and mounts it on the substrate P. I do. In the first embodiment, the pickup head 21 and the bonding head 41 are processing heads that perform mounting processing.

  In the above mounting process, as shown in the problem, for example, when the collet 60 held by the bonding head 41 is replaced, the amount of descent of the bonding head 41 is corrected due to variations in the height of the collet 60 during manufacture. There is a need.

  In the present embodiment, when the bonding head 41 that does not hold the die D is lowered to the prestage 31, when the suction flow rate L flowing in the suction path constituted by the suction holes 41v and the like becomes a predetermined flow rate, Is determined as an offset amount Zo suitable for various processes such as pick-up and bonding.

In the present embodiment, the prestage 31 is used as the measurement flat plate 50 for measuring the descent amount Z of the bonding head. The predetermined flow rate is defined as a flow rate at which the die D can be surely placed on the prestage 31 and the die D is not damaged. Based on this offset amount Zo, a lowering amount Z of the bonding head 41 held by or held by the die D, that is, the collet 60 to the prestage 31 and the substrate P is determined.
The predetermined adsorption flow rate R is the adsorption threshold flow rate Rv, and the distance from the prestage 31 of the collet 60 at the adsorption threshold flow rate Rv is the allowable distance Lv. FIG. 3 shows the relationship between the suction flow rate R and the collet descent amount Z, particularly the relationship between the suction threshold flow rate Rv and the allowable distance Lv.

Example 1
FIG. 4 is a view showing a first embodiment for determining the amount of lowering Z of the bonding head 41. In this embodiment, first, the vehicle descends at a high speed to a position Zt before the target position. Next, it is lowered until the threshold flow rate Rv becomes smaller than the permissible distance Lv. The position of Zt is determined in consideration of variations in the height of the collet 60 to be used. In this case, different die sizes may be processed in a lump, and in that case, the value of Zt may increase.
In this embodiment, the allowable distance Lv is +5 μm, and a 1 μm / pulse pulse motor is used as the Z-axis drive motor ZM.

  The specific flow is as follows. First, it is lowered at a high speed to 0.5 mm before the mounting surface of the prestage 31 which is the target position (S1). Next, the vacuum suction valve V is opened (S2). After that, it is lowered every 1 μm which is the control resolution of the pulse motor as a step unit (S3), and it is judged whether the adsorption flow rate is equal to or less than the adsorption threshold flow rate Lv (S4). Of course, the step unit may be 2 μm to 4 μm instead of 1 μm.

  Next, the position that has reached the arrival threshold flow rate Lv in S4 is stored as an offset amount Zo (S5). An amount obtained by adding the thickness of the die D to the offset amount Zo is set as a descending amount Zp in the prestage 31 (S6). Further, a value obtained by adding the offset in the Z direction between the surface of the prestage 31 and the substrate surface to the offset amount Zo is defined as a drop amount Zs when the die is mounted on the substrate (S7).

  In the first embodiment, by making the step unit smaller than the allowable distance Lv, the bonding head 41 can reliably process the die D on the wafer 11, the prestage 31, and the substrate P without dropping the collet 60 more than necessary. .

(Example 2)
FIG. 5 is a diagram showing a second embodiment for determining the descending amount Z of the bonding head 41. In the present embodiment, first, the vehicle is lowered at a high speed to the position Zt before the target position, and then lowered until the threshold flow rate Lv becomes smaller than the allowable distance Lv, and then the step unit smaller than the allowable distance Lv. Until the threshold flow rate Lv is exceeded. In the second embodiment, the allowable distance Lv is +5 μm, and a 1 μm / pulse pulse motor is used as the Z-axis drive motor ZM.

  Therefore, the differences of the second embodiment from the first embodiment are S23, S25, and S26. The other S21, S22, S24 and S27 to S29 correspond to S1, S2, S4 and S5 to S7, respectively, and are the same.

  In S23, the step unit is set to 10 μm, which is twice the allowable distance Lv, instead of 1 μm of S3 in the first embodiment. Steps S25 and S26 are not included in the first embodiment, and the step unit is raised as 1 μm of the control decomposition of the motor, which is 1/5 of the allowable distance Lv, and is stored within the allowable distance Lv.

  The second embodiment has an advantage that the position can be quickly reached before the target position Zt as compared with the first embodiment.

  According to the embodiment including Examples 1 and 2 described above, the amount of descending Z of the bonding head or the like can be automatically measured, and a highly reliable die bonder can be provided.

(Embodiment 2)
FIG. 6 is a conceptual view of the die bonder 200 according to the second embodiment of the present invention as viewed from above.
The die bonder 200 roughly includes a wafer supply unit 210, a workpiece supply / conveyance unit 220, a bonding unit 230, and a control unit 208 that controls each unit and a bonding flow in each embodiment described later.

  The workpiece supply / conveyance unit 220 includes a stack loader 221, a frame feeder 222, and an unloader 223. The workpiece supplied to the frame feeder 222 by the stack loader 221 is conveyed to the unloader 223 via two processing positions on the frame feeder 222.

  The wafer supply unit 210 includes a wafer cassette lifter 211 and a pickup device 212. The wafer cassette lifter 211 includes a wafer cassette (not shown) filled with wafer rings, and sequentially supplies the wafer rings to the pickup device 212. The wafer ring holds the wafer W having the die D, and the pickup device 212 holds the wafer ring.

  The bonding unit 230 includes a preform unit 231 and a bonding head unit 232. The preform unit 231 applies a die adhesive to the work conveyed by the frame feeder 222.

  The bonding head unit 232 includes a bonding head 41 and a measurement flat plate 50. The bonding head 41 picks up the die D from the pickup device 212 and moves up, and moves the die D in parallel to a bonding point on the frame feeder 222. Then, the bonding head 41 lowers the die D and bonds it onto the workpiece coated with the die adhesive. The measurement flat plate 50 is provided in place of the pre-stage 31 of the first embodiment, and is used for determining the descending amount Z of the bonding head 41 by the method described in Examples 1 and 2.

  As described above, the second embodiment differs from the first embodiment in that the pickup unit 2 is not provided, and the bonding head 31 directly picks up the die D from the wafer W and mounts it on a workpiece such as a substrate. is there. Therefore, in order to determine the descending amount Z of the bonding head 41 by the method described in the first and second embodiments, the measurement flat plate 50 is provided in the movable range of the bonding head 41. Even if the prestage 31 is changed to a measurement flat plate, the methods shown in Examples 1 and 2 can be applied without change. In the second embodiment, the bonding head 41 is the only processing head for performing the mounting process.

  Also in the second embodiment, the first and second embodiments can be provided, and the descent amount Z of the bonding head can be automatically measured as in the first embodiment, so that a highly reliable die bonder can be provided.

FIG. 7 is a diagram showing a die bonding flow in the first and second embodiments.
First, the collet 60 is attached to the bonding head (S1). The offset amount Zo is measured based on Example 1 or Example 2 (S2). Next, based on the offset amount Zo, the descent amount Z is corrected in order to perform the processing of the bonding head 41 and, if necessary, the pickup head 21 (S3). Thereafter, the die D is mounted (S4). During the mounting, the replacement time of the collet 60 is determined (S5). If exchange is necessary, go to S1, exchange the collet 60, and continue the process from S2. Finally, it is determined whether the predetermined mounting process has been completed, and the process is terminated (S6).

  According to the processing flow described above, the descent amount Z of the bonding head or the like can be automatically measured, and a highly reliable bonding method can be realized.

  The control shown in FIGS. 4, 5, and 7 is performed by the control unit provided in the control device 8 or the control device 208.

  Although the embodiments of the present invention have been described above, various alternatives, modifications, and variations can be made by those skilled in the art based on the above description. It encompasses alternatives, modifications or variations.

1: Die supply unit 11: Wafer 12: Wafer holder 13: Push-up unit 14: Wafer holding stage 15: XY drive unit 16: Rotation drive unit 2: Pickup unit 21: Pickup head 22: X drive shaft 24: Pickup nozzle Stocker 3: Pre-alignment unit 31: Pre-alignment stage (pre-stage)
4: Bonding unit 40v: Suction hole 41: Bonding head 41v: Suction hole 45: Bonding head nozzle stocker 47: Z drive shaft 5: Conveying unit 6: Substrate supply unit 7: Substrate unloading unit 8, 208: Control unit 50: Measurement flat plate 60: Collet 60v; Suction hole 61: Collet holder 61v; Suction hole 100, 200: Die bonder 210: Wafer supply unit 220: Workpiece supply / conveyance unit 230: Bonding unit D: Die Lv: Allowable distance P: Substrate PO: Pump RS: Flow sensor Rv: Adsorption threshold flow V: Vacuum adsorption valve Z: Descent amount Zo: Offset amount Zt: Position before the target position

Claims (16)

A collet that adsorbs the die,
A processing head that includes the collet at the tip and performs at least one of a suction process for sucking the die and a bonding process for bonding the die to a workpiece;
A measuring plate having a parallel surface parallel to the bonding surface to be bonded;
An adsorption flow rate measuring means for measuring an adsorption flow rate when the die is not held;
Elevating means for elevating and lowering the processing head;
The raising / lowering position of the processing head when the processing head not holding the die is lifted and lowered with respect to the measurement plate and the suction flow rate of the processing head crosses the suction threshold flow rate which is a predetermined suction flow rate. A control unit that calculates an amount of descent of the processing head during the processing based on the offset amount, and an offset amount;
A die bonder characterized by comprising: The die bonder according to claim 1, wherein
The control unit lowers the processing head from the measurement flat plate to a predetermined position at a high speed having at least a speed equal to or higher than that during the processing, and then an allowable distance that is a distance from the measurement flat plate at the adsorption threshold flow rate. Descent in steps based on
A die bonder characterized by that. The die bonder according to claim 2,
The die bonder according to claim 1, wherein the control unit lowers the step unit in small step units smaller than the allowable distance. The die bonder according to claim 2,
The control unit makes the step unit larger than the permissible distance and descends in large step units, and after the adsorption flow rate has crossed the adsorption threshold flow rate due to the lowering of the processing head, the control unit is made smaller than the permissible distance. A die bonder that is raised in steps. The die bonder according to claim 3 or 4,
The die bonder characterized in that the small step is a control resolution of a motor that moves the processing head up and down. The die bonder according to any one of claims 1 to 5,
The die bonder according to claim 1, wherein the processing head is a bonding head for adsorbing the die from a wafer and bonding the die to the workpiece. The die bonder according to any one of claims 1 to 5,
The processing head is a pickup head that sucks the die from the wafer and places the die on the pre-alignment stage, and a bonding head that picks up the die placed on the pre-alignment stage and bonds the die to the workpiece. Die bonder characterized by. The die bonder according to claim 7,
The die bonder according to claim 1, wherein the pre-alignment stage also serves as the measurement flat plate. An adsorption step to adsorb the die with the collet;
A process step of performing at least one of a process of adsorbing the die with a processing head including a tip collet and a process of bonding the die to a workpiece;
A raising and lowering step for raising and lowering a processing head not holding the die with respect to a measurement flat plate having a parallel plane parallel to the bonding surface to be bonded,
An adsorption flow rate measuring step for measuring the adsorption flow rate of the processing head during the elevation;
A descent amount for determining the descent amount of the processing head at the time of processing based on the offset amount, where the ascending / descending position of the processing head when the adsorption flow rate crosses the adsorption threshold flow rate that is a predetermined adsorption flow rate A step of seeking
A bonding method comprising: The bonding method according to claim 9, wherein
The raising / lowering step lowers the processing head from the measurement flat plate to a predetermined position at a high speed having at least a speed equal to or higher than that during the processing, and then an allowable distance that is a distance from the measurement flat plate at the adsorption threshold flow rate. Descent in steps based on
A bonding method characterized by the above. The bonding method according to claim 10, wherein
The ascending / descending step lowers the step unit by a small step unit that is smaller than the allowable distance. The bonding method according to claim 10, wherein
The ascending / descending step is configured such that the step unit is made larger than the permissible distance and is lowered in units of large steps, and the adsorbing flow rate crosses the adsorbing threshold flow rate due to the lowering of the processing head, so A bonding method characterized by raising in steps. The bonding method according to claim 11 or 12,
The bonding method according to claim 1, wherein the small step is a control resolution of a motor that moves the processing head up and down. In the bonding method according to any one of claims 9 to 13,
The bonding method according to claim 1, wherein the processing head is a bonding head that sucks the die from a wafer and bonds the die to the workpiece. In the bonding method according to any one of claims 9 to 13,
The processing head is a pickup head that sucks the die from the wafer and places the die on the pre-alignment stage, and a bonding head that picks up the die placed on the pre-alignment stage and bonds the die to the workpiece. A bonding method characterized by the above. The bonding method according to claim 15, wherein
The da-bonding method, wherein the pre-alignment stage also serves as the measurement flat plate.

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