JP6139926B2 - Die bonder and bonding method - Google Patents

Description

  The present invention relates to a die bonder and a bonding method, and more particularly to a die bonder and a bonding method having a high operating rate.

  There is a process of assembling a package by mounting a die (semiconductor chip) on a substrate such as a wiring board or a lead frame or a work such as a die already stacked on the substrate. As part of the assembly process, a semiconductor wafer (hereinafter simply referred to as a wafer), a pick-up process for picking up a die from a relay stage called an intermediate stage, and a bonding process for mounting the picked-up die on a substrate or die with a bonding head There is.

  In the pick-up process, the die is picked up using a suction device called a collet or suction nozzle. Whether the die to be picked up is adsorbed by the adsorbing device is monitored by monitoring the flow rate flowing through the adsorbing hole. Nowadays, with the miniaturization of the die size, this check needs to be able to be performed over a wide range of die sizes.

  FIG. 6A and FIG. 6B show conventional techniques of the adsorption flow rate detection circuit that performs the die size as described above over a wide range. The conventional technology of the die shown in FIG. 6A is provided with a flow rate sensor RSL suitable for a large size die and a flow rate sensor RSS suitable for a small size die in each of the flow paths BL and KL, depending on the die size. The flow rate sensor RSL and the flow rate sensor RSS are switched by the valve V. In the second prior art shown in FIG. 6B, the flow sensor RSL suitable for a large die and the flow sensor RSS suitable for a small die according to the die size are provided at the flow sensor installation position RSP. Replaced and installed.

FIG. 6C discloses a flow rate detection circuit for detecting clogging in the suction path of the suction nozzle described in Patent Document 1. In Patent Document 1, since a large volume of suction flow is required to operate many suction nozzles with certainty, the suction flow is passed through the operation line DL during normal operation. On the other hand, when clogging is detected, since it is necessary to detect a small volume flow rate, the flow is passed through a detection line KL with a flow rate sensor RS. This flow is controlled by the valve V.
In FIG. 6, reference numerals not described are the same as those described in the embodiment of the present invention.

JP 2011-215622 A

  The adsorption flow rate detection circuit of the first prior art requires two flow sensors and a valve, and the circuit is complicated, and there is a problem that valve switching control is required according to the die size. The adsorption flow rate detection circuit of the second prior art can solve the problem of the first prior art, but it is complicated because the flow rate sensor needs to be replaced according to the die size. Moreover, since replacement time is required, there is a problem that the operating rate of the apparatus is reduced.

  The flow rate detection circuit for clogging in Patent Document 1 has a different purpose and configuration as described later.

  Accordingly, an object of the present invention is to provide a die bonder and a bonding method having a high operating rate by determining the presence or absence of die adsorption with a simple circuit configuration.

In order to achieve the above object, the present invention has at least the following features.
The present invention relates to a die bonder or a bonding method in which a processing head is moved up and down, a die is picked up and picked up by the processing head, a detection flow path provided with a flow sensor, and provided in parallel with the detection flow path, Is detected by the flow rate sensor of the adsorption flow rate detection circuit comprising a bypass flow channel directly connected to the detection flow channel, and the die is adsorbed based on the detection result of the flow rate sensor. It is determined that the device has been adsorbed.

In the present invention, a valve for opening and closing the bypass channel may be provided in the bypass channel.
Further, according to the present invention, the diameter ratio of the bypass flow path to the detection flow path or the flow resistance ratio N (N is a positive real number) viewed from the air suction means is a die within a detection range of the flow path sensor. The determination value of whether or not the die having the size is adsorbed may be determined by a numerical value within a detection range of the flow sensor.

  Further, in the present invention, the processing head sucks and picks up the die from the wafer and places the pick-up head on the pre-alignment stage, or picks up and picks up the die from the wafer or the pre-alignment stage, A bonding head for bonding to a workpiece may be used.

  Further, the present invention performs the adsorption of the die with a bonding head having a collet at the tip, and when picking up the die, opens the valve, performs the determination based on the result of the flow sensor, and the collet When the valve is replaced, the valve is closed, the bonding head is lowered, the amount of the bonding head is lowered with respect to the measurement plate based on the detection result of the flow sensor, and the thickness of the collet is determined based on the amount of the lowering. A variation in the height may be obtained to correct the descent amount of the bonding head when picking up.

  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 which shows the schematic of the die bonder which is the 1st Embodiment of this invention. It is a figure explaining the structure of the 1st Example of the adsorption | suction flow volume detection circuit in this Embodiment 1, and its operation | movement. It is a figure explaining the principle applicable to the wide die size of an adsorption flow rate detection circuit compared with a prior art. It is a figure explaining the structure of the 2nd Example of the adsorption | suction flow volume detection circuit in this Embodiment 1, and its operation | movement. 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 a prior art.

(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 (or 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, and the operations of the pickup head and the bonding head are minimized.

  In such a die bonder, it is necessary to replace the collet according to the wafer 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. There is. 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 thereon by 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 to. The first and second transport units can be driven independently of each other.

  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 first embodiment of the die bonder described above, when the pickup head 21 picks up the die from the wafer 11 or picks up the die from the prestage 31 with the bonding head 41, the suction flow rate is monitored and the collet 60 is Tick whether die D is adsorbed and pick up the die. Hereinafter, an embodiment of the adsorption flow rate detection circuit 70 for detecting the adsorption flow rate will be described.

Example 1
FIG. 2 is a diagram for explaining the configuration and operation of the first example 70A of the adsorption flow rate detection circuit 70 according to the first embodiment. 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 head 41 includes a collet holder 61 that holds the collet 60 and can replace 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 is connected to the adsorption flow rate detection circuit 70A via the connection flow path CL.

  The adsorption flow rate detection circuit 70A has a branch path 71 from the connection flow path CL to the detection flow path KL having the flow sensor RS and the bypass flow path BL. The two flow paths merge again on the side of the pump PO that sucks the flow rate, and are connected to the pump PO that is an air suction means.

  The control device 8 shown in FIG. 1 has a control unit 8C that takes in the flow rate from the flow rate sensor RS, determines whether or not the die is reliably adsorbed, and controls the pump PO. The control unit 8C also controls the bonding head 41. The control device 8 includes a memory 8M that stores a program necessary for determination and control, threshold data for determining whether the suction has been performed, control data, and the like, a driver 47D for the Z drive shaft 47 of the bonding head 41, and a motor 47M. Is provided. The control unit 8C drives the driver 47D with data and position information obtained in advance. Although FIG. 1 has four bonding heads, FIG. 2 shows only one structure because each bonding head 41 has the same structure.

FIG. 3 is a diagram for explaining the principle of the adsorption flow rate detection circuit 70 applicable to a wide range of die sizes in comparison with the prior art shown in FIG. The horizontal axis in FIG. 3 indicates the die size Dd, and the vertical axis indicates the determined adsorption flow rate RH at each die size Dd.
In FIG. 3, the curve indicated by the alternate long and short dash line indicates a determination adsorption flow rate curve RHj for determining whether or not a die with respect to a conventional die size is adsorbed. In the first prior art, the flow rate sensor RSS having the maximum detection flow rate RDm and having a determination range up to the die size Dc and the flow rate sensor RSL having the determination range having a minimum detection flow rate equal to or larger than the die size Ds are switched. Covers the die size. The flow rate sensor RSL has a minimum detected flow rate RDs that is smaller than the maximum detected flow rate RDm of the flow rate sensor RSS.

  On the other hand, in the first embodiment, the flow path resistance on the detection flow path KL side including the bypass flow path BL and the flow rate sensor RS shown in FIG. 2 is set to 1 to N (N> 0). As a result, of the flow rate RC flowing through the connection flow path CL, the flow rate flows through the detection flow path KL at a distribution ratio DR = 1 / (1 + N). As a result, the determination flow rate curve RHi of Example 1 shows a curve indicating the flow rate of R / (1 + N) of the determination flow rate curve RHj of the prior art.

  Then, a flow rate sensor RS is used in which the determination flow rate at the applied minimum die size Ds is larger than the detection sensitivity, and the determination flow rate at the applied maximum die size Dm is smaller than the maximum detection flow rate RDm of RSS RDm, for example.

  In the above description, N is simply set as N> 0, but N should be larger to some extent.

  In the above description, the distribution ratio is defined by the flow path resistance. However, the distribution ratio may be simply defined by the pipe diameter ratio of the bypass flow path BL and the detection flow path KL.

  As a result, according to the first embodiment, the presence / absence of adsorption can be reliably detected by one flow rate sensor RS in all the die sizes to be applied.

(Example 2)
Next, a second example 70B of the adsorption flow rate detection circuit 70 according to the first embodiment will be described. FIG. 4 is a diagram illustrating the configuration and operation of the example 70B. In the first embodiment, no valve is provided, but in the second embodiment, the valve V is provided in the bypass line BL.

  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.

  In the second embodiment, by opening the valve V, it is possible to detect the presence or absence of adsorption when the die D described in the first embodiment is picked up. On the other hand, by closing the valve V, it is possible to form a descending flow rate detection circuit that can detect a change in the descending amount of the bonding head 41 due to variations in the thickness of the collet when the collet is replaced.

  The amount of descent of the bonding head 41 is detected by lowering the collet 60 onto a measurement flat plate such as the pre-stage 31 without holding a die on the bonding head 41, and at that time the adsorption flow rate flowing through the suction path composed of the suction holes 41v and the like A descent amount Z of the bonding head is detected when L reaches a predetermined flow rate. The difference in the collet thickness based on the variation in the thickness of the collet when the collet is manufactured is detected based on the difference between the descent amount Zb of the bonding head before the collet replacement and the descending amount Za of the bondin head after the collet replacement. . When the die D is picked up by the collet after replacement, the descent amount of the bonding head is corrected by the difference. The predetermined flow rate is defined as a flow rate at which the die D can be reliably placed on the prestage 31 and the die D is not damaged.

  The allowable error set as the amount of descent in the above is several μm. Therefore, when the die size is small, it is difficult to detect the amount of decrease in the state in which the valve V is opened, that is, the state of the adsorption flow rate detection circuit 70A of the first embodiment because the flow rate is small. However, when the die size is large, the amount of descent can be detected even when the valve V is open.

  When measuring the amount of descent, it is lowered roughly until just before the pre-stage 31, but after approaching the pre-stage 31, it is finely stepped or slightly overrun, and then the accuracy is increased while finely raising the step. Detect well.

  In the second embodiment described above, by providing the valve V in the bypass line BL, the suction flow rate can be detected when the die D is picked up, and when the collet is replaced, the bonding head can be changed due to variations in thickness at the time of manufacturing the collet. A change in the amount of descent can be detected.

(Embodiment 2)
FIG. 5 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 is roughly divided into a wafer supply unit 210, a workpiece supply / conveyance unit 220, a bonding unit 230, and a control device 208 that performs control of each unit, determination of the presence / absence of suction based on the suction flow rate, detection of a descent amount, and the like. Prepare.

  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 the second embodiment. In the second embodiment, the bonding head 41 is the only processing head that performs the mounting process.

  As described above, the second embodiment differs from the first embodiment in that there is no pickup unit 2 or prestage unit 3 and the bonding head 41 directly picks up the die D from the wafer W, and the workpiece such as a substrate. It is a point to attach to. Therefore, Example 1 can be applied to Embodiment 2 without any change. The second embodiment can be applied to the second embodiment by correcting the amount of descent of the bonding head 41 with the measurement flat plate 50.

  Therefore, also in the second embodiment, the same effects as in the first embodiment can be obtained in the first and second embodiments.

  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, and the present invention is not limited to the various embodiments described above without departing from the spirit of the present invention. It encompasses alternatives, modifications or variations.

1: Die supply unit 11: Wafer 2: Pickup unit 21: Pickup head 3: Pre-alignment unit
31: Pre-alignment stage (pre-stage)
4: Bonding part 40v, 41v: Suction hole 41: Bonding head 47: Z drive shaft 8, 208: Control part 50: Measurement flat plate 60: Collet 60v, 61v; Suction hole 61: Collet holder 70, 70A, 70B: Adsorption flow rate Detection circuit 71: Branch path 100, 200: Die bonder 230: Bonding part BL: Bypass flow path CL: Connection flow path D: Die KL: Detection flow path P: Substrate PO: Pump RDm: Maximum detection flow rate of flow sensor RSS RDs: Minimum detected flow rate of flow rate sensor RSL RH: judgment adsorption flow rate RHi: judgment flow rate curve of Example 1 RHj: prior art judgment flow rate curve RS: flow rate sensor V: valve

Claims (7)

An adsorber that adsorbs the die;
A processing head that includes the suction device 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;
Elevating means for elevating and lowering the processing head;
An adsorption flow rate detection circuit comprising a detection flow path provided with a flow rate sensor, and a bypass flow path provided in parallel with the detection flow path and having both ends connected directly to the detection flow path;
Air suction means for sucking air through the suction flow rate detection circuit;
A control unit comprising determination means for determining that the die is adsorbed to the adsorption device based on the detection result of the flow sensor;
Have
A die bonder, wherein a valve for opening and closing the bypass channel is provided in the bypass channel. The die bonder according to claim 1,
The diameter ratio of the bypass channel to the detection channel or the channel resistance ratio N (N is a positive real number) viewed from the air suction means is the adsorption of the die having a die size within the detection range of the flow sensor. A die bonder characterized in that a determination value for the presence or absence of the flow rate is determined by a numerical value within a detection range of the flow sensor. The die bonder according to claim 1,
The processing head picks up and picks up the die from the wafer and places it on a pre-alignment stage, or a bonding head that picks up and picks up the die from the wafer or the pre-alignment stage and bonds it to the workpiece A die bonder characterized by being. The die bonder according to claim 1,
The adsorption device is a collet;
The processing head is a bonding head that sucks and picks up the die from a wafer or a pre-alignment stage, and bonds the die to the workpiece.
The control unit controls to open the valve when picking up the die, and to close the valve when replacing the collet, and from the detection result of the flow sensor, the amount of movement of the bonding head relative to the measurement plate The die bonder is characterized in that a variation in thickness of the collet is obtained from the amount of movement, and a descent amount when the bonding head picks up the die is corrected. Raising and lowering the processing head, sucking and picking up the die with the processing head,
The processing is performed by the flow rate sensor of the adsorption flow rate detection circuit that includes a detection flow path provided with a flow rate sensor and a bypass flow path that is provided in parallel with the detection flow path and has both ends connected directly to the detection flow path. Detecting the suction flow rate when the head sucks the die,
It determines that the die on the basis of the detection result of the flow rate sensor is adsorbed in adsorption Chakukigu,
A bonding method comprising providing a valve for opening and closing the bypass channel in the bypass channel. The bonding method according to claim 5, wherein
Wherein the processing head is picked up by suction the die from the wafer, the pickup head is mounted on the prealignment stage, or adsorbed to pick up the die from a wafer or the pre-alignment stage, bonded to the ring over click bonding A bonding method characterized by being a head. The bonding method according to claim 5, wherein
The die is adsorbed with a bonding head having a collet at the tip,
When picking up the die, open the valve, make the determination based on the result of the flow sensor,
When exchanging the collet, the valve is closed, the bonding head is lowered, the amount of descent of the bonding head with respect to the measurement plate is obtained based on the detection result of the flow sensor, and the collet is based on the amount of descent. A bonding method characterized in that a variation in thickness of the bonding head is obtained, and a descent amount of the bonding head at the time of picking up is corrected.

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