JP5191753B2 - Die bonder and die bonding method - Google Patents

Description

The present invention relates to a die bonder and a die bonding method for mounting a semiconductor chip or the like on a lead frame or the like.

  A die bonder (for example, Patent Document 1 and Patent Document 2) picks up a chip (semiconductor chip) with a collet at a pickup position and bonds the chip to a substrate at a bonding position.

  First, a semiconductor chip is formed with a large number of semiconductor elements on a silicon wafer or the like. Thereafter, the wafer on which the large number of semiconductor elements are formed is adhered to an adhesive sheet, and the semiconductor elements are cut and separated by dicing to manufacture a large number of semiconductor chips. Next, in a state where the adhesive sheet is extended in the radial direction and the interval between the semiconductor chips is widened, the peripheral portion of the adhesive sheet is fixed to the metal ring, and the semiconductor chip is adsorbed from the adhesive sheet with a collet (adsorption nozzle). . Thus, the pickup is picked up, transferred to a substrate position such as a lead frame, and bonded to the substrate.

  That is, as shown in FIG. 4, the collet 1 is moved upward and downward in the direction of arrow A on the pickup position P and lowered in the direction of arrow B and the arrow C on the bonding position Q via a moving mechanism (not shown). It is possible to move up and down in the direction of arrow D and to reciprocate in the directions of arrows E and F between the pickup position P and the bonding position Q. In the moving mechanism, the movement of the arrows A, B, C, D, E, and F is controlled by a control unit configured by, for example, a microcomputer. The pickup position is often higher than the bonding position.

  Incidentally, as shown in FIG. 4, when bonding the chip 3 having the adhesive layer 2 on the silicon back surface, it is necessary to heat the substrate 4 such as a lead frame by a heating means such as a heater rail 5. And the chip | tip 3 currently hold | maintained at the collet 1 was pressed by applying a predetermined load for a predetermined time, and the required joint strength was obtained.

  The moving mechanism enables the collet 1 to move along the X axis (horizontal axis), the Y axis (horizontal axis orthogonal to the X axis), and the Z axis (vertical axis). Usually, teaching is executed before operation.

In this case, manual setting of the bottom dead center position (lowest point) at the mount position (bonding position) is performed before operation.
JP 2003-174042 A

  As described above, when the lead frame is heated by heating means such as the heater rail 5, the lead frame needs to be heated to the melting point of the solder or higher. Then, a plurality of semiconductor chips are transferred. For this reason, the temperature of the collet and the collet holder that supports the collet is different between the start of operation and during operation due to this temperature environment, and the height of the collet suction surface at the start of descent at the bonding position Q It fluctuates at the start and during operation.

  Therefore, there is a possibility that the optimum load for obtaining the required bonding strength cannot be applied to the chip from the start of operation to the end of operation, or the load may be excessively applied to the chip. That is, as shown in FIG. 5, if teaching is performed in a state indicated by a solid line, the state is lowered by a predetermined amount H from the state indicated by the solid line. In this case, the position of the collet tip surface (suction surface) 1a (the position indicated by the solid line) is an intermediate position between the position at the start of operation and the position at the end of operation. For this reason, at the uppermost point at the bonding position Q, for example, the suction surface 1a of the collet 1 is positioned as indicated by the virtual line 1a1 or positioned as indicated by the virtual line 1a2. Even in such a case, the collet 1 is lowered by the predetermined amount H.

  As indicated by the imaginary line 1a1, when the suction surface 1a is lower than the normal position (reference position), the lowest point is lower than the set position and an excessive load is applied to the chip 1. Become. On the contrary, as shown by the virtual line 1a2, when the suction surface is higher than the normal position, the lowest load is higher than the set position, and the optimum load for obtaining the required bonding strength The chip cannot be loaded.

  In view of the above problems, the present invention provides a die bonder and a die bonding method capable of bonding chips with high accuracy even when there is a temperature fluctuation during operation.

Die bonder of the present invention carries the collet are adsorbed chip to bonding position, the die bonder for bonding a chip to a substrate is lowered along the collet in a vertical direction in this bonding position, the temperature at the tip pickup position Adjustment means for adjusting the amount of vertical movement at the pickup position based on the decrease, height detection means for detecting the height of the collet suction surface at the bonding position, and the collet detected by the height detection means And a control means for controlling a vertical movement amount of the collet at the bonding position based on the height of the suction surface.

  According to the die bonder of the present invention, the height of the collet suction surface can be detected at the bonding position by the height detection means. Further, the amount of vertical movement of the collet at the bonding position is controlled by the control means based on the detected height of the collet suction surface. In other words, even if there are temperature fluctuations, the height of the collet suction surface at the lowest point of vertical movement at the bonding position can be kept constant, and the optimum load to obtain the required bonding strength The chip can be loaded.

  The control means includes a basic control means for controlling the collet to move according to a preset moving direction and moving amount, and a bonding position of the basic control means based on the height detected by the height detecting means. It is preferable to include correction control means for performing feedback control of the vertical movement amount of the collet.

  The collet can be moved according to a preset moving direction and moving amount by the basic control means, and a stable bonding operation can be performed. Also, when the collet suction surface fluctuates (displaces) with respect to the reference position due to the influence of temperature, etc., the correction control means moves in the vertical direction at the bonding position according to this fluctuation (displacement). The amount can be changed.

  By the way, at the pickup position, the chip is usually pushed up by a push-up pin, and the chip is sucked onto the suction surface of the collet that has been lowered in this state. For this reason, if the height position of the collet suction surface at the lowest point is different, the chip suction (delivery) work will be hindered. That is, if the height position of the collet suction surface at the lowest point is lower than the reference setting position, the tip is sandwiched between the push-up pin and the collet suction surface, and the tip is damaged by the push-up pin. There is a case. On the contrary, if the height position of the collet suction surface at the lowest point is higher than the reference setting position, the chip may not be attracted to the suction surface, or the position may be shifted even if it is attracted.

  Therefore, the height detection means for detecting the height of the collet suction surface at the pickup position, and the vertical movement amount of the collet at the pickup position based on the height of the collet suction surface detected by the height detection means. Control means for controlling may be provided.

  As described above, in the control of the vertical movement amount on the pickup position side, the chip is picked up with the optimum vertical movement amount for picking up even if the height position of the collet suction surface changes during operation. can do.

The die bonding method of the present invention is a die bonding method in which a collet adsorbing a chip is conveyed to a bonding position, and the collet is lowered along the vertical direction at this bonding position to bond the chip to a substrate . The amount of vertical movement at the pickup position is controlled based on the temperature drop at the pickup position, the height of the collet suction surface is detected at the bonding position, and the collet at the bonding position is detected based on the height of the collet suction surface. Feedback control of the amount of movement in the vertical direction is performed.

  According to the die bonding method of the present invention, even if the suction surface of the collet fluctuates (displaces) with respect to the reference position, the vertical movement amount at the bonding position can be changed according to the fluctuation (displacement). it can. For this reason, even during operation, an optimum load for obtaining the required bonding strength can be applied to the chip.

  The feedback control may be performed for each bonding or may be performed for each predetermined number of bondings.

  In particular, immediately after exchanging the wafer ring at the chip pickup position, a relatively long time has elapsed since the bonding process for the previous wafer, and the height of the collet suction surface at the bonding position may vary greatly. For this reason, it is preferable to perform feedback control immediately after wafer ring replacement.

  In the present invention, even if the height of the collet suction surface fluctuates between the start of operation and during operation due to the influence of temperature change, the required amount of bonding strength is obtained as the vertical movement amount at the bonding position. This is an amount capable of applying an optimum load for obtaining the chip. For this reason, it is possible to perform highly accurate bonding work stably from the start of operation to the end of operation, and the variation in quality is reduced.

  With the basic control means and the correction control means, it is possible to improve the reliability of the correction of the vertical movement amount at the bonding position.

  If the amount of vertical movement on the pickup position side is controlled, the chip can be picked up with the optimum amount of vertical movement for picking up even if the collet suction surface fluctuates during operation. Can do. For this reason, the chip can be maintained in a high quality state, and the die bonding operation can be stabilized.

  When feedback control is performed for each bonding, the entire bonding process can be performed with high accuracy. Usually, since the height of the collet suction surface does not fluctuate every bonding, even if it is performed every predetermined number of times, the accuracy of the bonding work does not decrease. For this reason, if it is performed every predetermined number of times of bonding, control can be simplified.

  By performing feedback control immediately after exchanging the wafer ring, an optimum load for obtaining the required bonding strength can be applied to the chip even in such a state where the temperature fluctuation is large.

  In the case of controlling the amount of vertical movement at the pickup position based on the temperature drop at the chip pickup position, the chip pickup operation is stabilized even in the chip pickup position process.

  Embodiments of the present invention will be described below with reference to FIGS.

  As shown in FIG. 2, the die bonder according to the present invention picks up a chip 11 cut out from a wafer at (pickup position P) and transfers (mounts) it to a bonding position Q of a substrate 12 such as a lead frame. It is. The wafer is adhered on a wafer sheet stretched on a metal ring (wafer ring), and is divided (divided) into a large number of chips 11 by a dicing process.

  This die bonder includes a collet 13. The collet 13 is moved by the moving mechanism 19 (see FIG. 1) in the direction of arrow A and lowered in the direction of arrow B on the pickup position P, and in the direction of arrow C on the bonding position Q and in the direction of arrow D. And a reciprocating motion in the directions of arrows E and F between the pickup position P and the bonding position Q are possible. The movement mechanism 19 is controlled by the control means 22 to move the arrows A, B, C, D, E, and F. The moving mechanism 19 can be constituted by various mechanisms such as a cylinder mechanism, a ball screw mechanism, and a motor linear mechanism, and an XYZθ axis stage, a robot arm that can move in the XYZθ directions, or the like can be used. it can.

  The collet 13 is formed with a suction hole for suction that opens at a lower end surface (suction surface) 13a, and a vacuum generator (not shown) is connected to the suction hole. By driving the vacuum generator, air in the suction hole is sucked, the chip 11 is sucked by vacuum, and the chip 11 is sucked to the lower end surface of the collet 13. When this vacuum suction (evacuation) is released, the chip 11 is detached from the collet 13. As the vacuum generator, for example, an ejector type that controls opening / closing of high-pressure air and discharges it from the nozzle to the diffuser to generate a negative pressure in the diffusion chamber can be adopted.

  The wafer divided (divided) into a large number of chips 11 is placed on, for example, an XYθ table 15, and push-up means having push-up pins are placed on the XYθ table 15. That is, the chip 11 to be picked up is pushed up from below by the pushing-up means, and is easily peeled off from the adhesive sheet. In this state, the chip 11 is adsorbed to the collet 13 that has been lowered.

  The substrate 12 is heated by the substrate heating means 16. The substrate heating means 16 is composed of, for example, a heater rail (not shown) with a built-in heater. And the base material 12 is conveyed on a heater rail intermittently in the arrow G direction, for example.

  And this die bonder is provided with the said control means 22 which has the basic control means 20 and the correction | amendment control means 21, as shown in FIG. The basic control means 20 controls the collet to move according to a preset moving direction and moving amount. Note that the control means 22, that is, the basic control means 20 and the correction control means 21 can be constituted by a microcomputer, for example.

  That is, the basic control means 20 moves up and down in the directions of arrows A and B at the pickup position P and the amount of movement thereof, horizontally moved and moved in the directions of arrows E and F, and in the directions of arrows C and D at the bonding position Q. Controls vertical movement and the amount of movement. In this case, teaching is executed before operation, and the basic control means 20 is programmed (teaching) so that the collet 13 moves in the order of arrows B, A, E, D, C, F.

  The correction control means 21 performs feedback control of the vertical movement amount at the bonding position Q of the basic control means 20 based on the height of the collet suction surface 13a detected by the height detection means 25.

  As the height detection means 25, a contact sensor of a mechanical switch such as a limit switch or a micro switch, a non-contact sensor such as a proximity sensor, a photoelectric sensor, or an ultrasonic sensor can be used. A proximity sensor is a sensor that detects that a detection object is approaching without contact, and is a high-frequency oscillation type that uses electromagnetic induction, a magnetic type that uses magnets, or a capacitance type that uses changes in capacitance. Etc. In addition, the photoelectric sensor emits light such as visible light and infrared light as signal light from the light projecting part, and the light reflected by the detection object is detected by the light receiving part (reflective type), or the amount of light that is blocked is changed. Is detected by a light receiving unit (transmission type / regressive reflection type) to obtain an output signal. The ultrasonic sensor emits an ultrasonic wave from the sensor head, receives the ultrasonic wave reflected by the object again by the sensor head, and measures the time from the transmission of this sound wave to the reception to determine the position of the object. It is to detect.

  Data on the height of the collet suction surface 13 a detected by the height detection means 25 is input to the correction control means 21. The correction control means 21 compares the detected height of the collet suction surface 13a (detected height) with the height of the collet suction surface 13a set by the basic control means 20 (reference height). Then, when the detected height is different from the reference height, the descent amount in the arrow D direction is corrected in consideration of the difference amount. In other words, feedback control is performed, and the position of the lowest collet suction surface 13a at the bonding position Q is set to a position where an optimum load for obtaining the required bonding strength can be applied to the chip 11.

  The height detection position of the collet suction surface 13a may be the bonding position Q, whether it is at the start of descent at the bonding position Q (top point) or at the end of descent at the bonding position Q (lowest point). It may be at the time of rising or falling. As the height position detection at the end of descent at the bonding position Q (the lowest point), a pressing force at the time of bonding may be detected by a pressure sensor and detected by this pressing force.

  As the height detection position, at the bonding position Q, when the descent starts at the bonding position Q (top point) or at the start of ascent (bottom point), the total descent amount at the bonding position Q is corrected. It is possible to control the position of the collet suction surface 13a at the lowest point. Further, since the detection position is known in the middle of the descent, the collet 13 descends and the suction surface passes through the detection position, so that the fluctuation amount of the collet suction surface 13a at this detection position can be detected. Therefore, by correcting the descending amount from the detection position, the position of the collet suction surface 13a at the lowest point at the bonding position Q can be controlled.

  Next, a bonding method using the above-described die bonder will be described. First, on the pickup position P, the collet 13 is moved (lowered) in the direction of arrow B, and the chip 11 on the XYθ table 15 is attracted to the collet attracting surface 13a. At this time, the tip 11 to be picked up is pushed up from below by the pushing-up means. Next, after raising the collet 13 along the arrow A direction, the collet 13 is moved horizontally along the arrow E direction to be positioned on the bonding position Q.

  Thereafter, the chip 11 is lowered by a certain amount along the vertical direction as indicated by an arrow D. Then, the suction of the chip 11 by the collet 13 is released at the lowest point, and the chip 11 is mounted. After mounting, it is raised in the direction of arrow C by the amount of lowering, then horizontally moved in the direction of arrow F, returned to the pickup position P, and the next chip 11 is picked up. Thereafter, the above steps are sequentially performed, and all the chips 11 on the wafer ring are mounted on the mounting portion (island portion) on the bonding position Q.

  In the present invention, the height position of the suction surface 13a of the collet 13 is detected by the height detection means 25 on the bonding position Q. Then, the collet suction surface 13a set by the basic control means 20 is compared with the height (reference height). Then, when the detected height is different from the reference height, the descending amount in the direction of arrow D is corrected in consideration of the difference amount, and the collet 13 is lowered by this descending amount in the next bonding. If the detected height coincides with the reference height, it is lowered in the direction of arrow D by the lowering amount based on the basic control means 20 without correcting the lowering amount.

  As a result, the position of the lowest collet suction surface 13a at the bonding position Q can be controlled. For this reason, the optimal load for obtaining the required bonding strength can be applied to the chip, and the chip 11 and the mounted part (island part) can be mounted.

  In the present invention, even if the suction surface 13a of the collet 13 fluctuates (displaces) with respect to the reference position due to a change in the temperature environment at the bonding position Q, the vertical at the bonding position Q depends on this fluctuation (displacement). The amount of direction movement can be changed. For this reason, the optimum load for obtaining the required bonding strength can be applied to the chip even during operation, and stable and highly accurate bonding work can be performed from the start of operation to the end of operation.

  The height detection means 25 can detect the height of the collet suction surface 13a at the bonding position Q, and the control means makes the vertical direction at the bonding position Q based on the detected height of the collet suction surface 13a. The amount of movement can be controlled, and the reliability of correction of the amount of movement in the vertical direction at the bonding position Q can be improved.

  In the embodiment, feedback control is performed for each bonding. For this reason, there is an advantage that almost all bonding processes can be performed with high accuracy. However, since the height of the collet suction surface 13a does not fluctuate for each bonding, the accuracy of the bonding work does not decrease even if it is performed every predetermined number of times. For this reason, if it is performed every predetermined number of times of bonding, control can be simplified. The predetermined number of times of bonding can be arbitrarily set, may be every 2 to 3 times, may be further every 5 to 6 times, and may be every indefinite time.

  In the die bonder, the bonding process for the next wafer is performed by exchanging the wafer ring. For this reason, when the chip 11 to be bonded is replaced, if the wafer ring is replaced, a relatively long time has passed since the bonding process for the previous wafer, and the height of the collet suction surface 13a at the bonding position Q varies greatly. There is a risk that. For this reason, it is preferable to perform the feedback control of the present invention immediately after exchanging the wafer ring.

  By the way, even in the pickup position, a problem may occur in the pickup at a certain vertical movement amount taught. That is, if the height position of the collet suction surface 13a at the lowest point is lower than the reference setting position, the chip 11 is sandwiched between the push-up pin and the collet suction surface 13a, and the chip 11 is moved by the push-up pin. You may get hurt. Conversely, if the height position of the collet suction surface 13a at the lowest point is higher than the reference setting position, the chip 11 may not be attracted to the suction surface 13a, or the position may be shifted even if it is attracted. .

  Therefore, as a die bonder, the pickup is based on the height detection means (not shown) for detecting the height of the collet suction surface 13a at the pickup position P and the height of the collet suction surface detected by the height detection means. Control means for controlling the vertical movement amount of the collet 13 at the position P (control means that can be configured by the control means 22) may be provided.

  As described above, in the case of controlling the vertical movement amount on the pickup position side, even if the height position of the collet suction surface 13a varies during operation, the chip 11 has the optimum vertical movement amount for picking up. Can be picked up. For this reason, the chip 11 can be maintained in a high quality state, and the die bonding operation can be stabilized.

  As described above, when the wafer ring is exchanged, it takes time until the re-operation is started, so that the temperature of the collet 13 is lowered. For this reason, the amount of movement of the collet 13 in the vertical direction at the pickup position may be controlled based on the temperature drop at the pickup position of the chip 11.

That is, the time from the last final operation to the re-operation is detected by the time detection means 26 such as a timer as shown in FIG. 3, and the temperature decrease amount of the collet 13 is estimated from this time and set in advance. The height position of the suction surface 13a in this state is calculated from the height position of the suction surface 13a of the collet 13 at this temperature. Therefore, the calculated height position of the suction surface 13a is fed back to the control means 22, and the amount of movement of the collet 13 in the vertical direction at the pickup position P is controlled (adjusted). Adjustment means for adjusting the amount of vertical movement at the pickup position P based on the temperature drop at the pickup position P of the chip 11 can be configured by the control means 22.

  As described above, when the movement amount in the vertical direction at the pickup position P is controlled based on the temperature drop at the pickup position P of the chip 11, the pickup operation of the chip 11 is stable even in the process of the pickup position P of the chip 11. To do.

  For this reason, in the case of controlling the vertical movement amount at the pickup position P based on the temperature drop, it is not necessary to provide a device for detecting the height position of the suction surface 13a and controlling the movement amount. In the case of providing a device that detects the height position of the suction surface 13a and controls the movement amount, it is not necessary to provide a device that controls based on a temperature drop. Of course, both control methods may be provided.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, when detecting the height of the suction surface 13a of the collet 13, the suction is performed. Even if the surface 13a itself is detected, the height position is detected on the lower surface (the anti-adsorption surface side) of the chip 11 where the chip 11 is adsorbed to the adsorption surface 13a, and the thickness of the chip 11 is subtracted. You may do it. The collet 13 may be a metal collet, a resin collet, or a rubber collet.

It is a simplified block diagram of the die bonder which shows embodiment of this invention. It is a simplification figure showing movement of a collet. It is a simplified block diagram of the die bonder which shows other embodiment of this invention. It is a simplified diagram showing the movement of a conventional collet. It is a simplified diagram of a collet for explaining a conventional defect.

Explanation of symbols

11 Chip 13 Collet 13a Collet suction surface 20 Basic control means 21 Correction control means 22 Control means 25 Height detection means

Claims (7)

In the die bonder that transports the collet adsorbing the chip to the bonding position and lowers the collet along the vertical direction at this bonding position to bond the chip to the substrate.
Adjusting means for adjusting the amount of vertical movement at the pickup position based on the temperature drop at the pickup position of the chip;
Height detection means for detecting the height of the collet suction surface at the bonding position, and the amount of vertical movement of the collet at the bonding position is controlled based on the height of the collet suction surface detected by the height detection means. A die bonder comprising a control means. The control means includes a basic control means for controlling the collet to move according to a preset movement direction and movement amount, and a bonding position of the basic control means based on the height detected by the height detection means. 2. The die bonder according to claim 1, further comprising correction control means for feedback-controlling the vertical movement amount of the collet. A die bonder that picks up a chip with a collet at the pickup position.
A height detection means for detecting the height of the collet suction surface at the pickup position, and a vertical movement amount of the collet at the pickup position is controlled based on the height of the collet suction surface detected by the height detection means. The die bonder according to claim 1, further comprising a control unit. In the die bonding method in which the collet adsorbing the chip is transported to the bonding position, the collet is lowered along the vertical direction at this bonding position, and the chip is bonded to the substrate.
Based on the temperature drop at the pickup position of the chip, the amount of vertical movement at the pickup position is controlled,
A die bonding method comprising: detecting a height of a collet suction surface at a bonding position, and performing feedback control of a vertical movement amount of the collet at the bonding position based on the height of the collet suction surface.   The die bonding method according to claim 4, wherein the feedback control is performed for each bonding.   The die bonding method according to claim 4, wherein the feedback control is performed every predetermined number of times of bonding.   5. The die bonding method according to claim 4, wherein the feedback control is performed immediately after exchanging the wafer ring at a chip pickup position.

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