Semiconductor manufacturing apparatus and semiconductor manufacturing method

Abstract

To provide semiconductor manufacturing equipment used for wire bonding, whereby the fixing torque is made uniform by motor control when the lead frame is fixed with a jig, thereby enabling stable wire bonding.SOLUTION: Semiconductor manufacturing equipment of the present disclosure is configured to have a lower jig having a lead frame mounting surface on its upper surface, an upper jig located in the direction of the upper surface of the lower jig, a ball screw fixed to the upper jig, a motor that rotates the ball screw and holds the lead frame between the lower and upper jigs, a current measuring device that measures the current value flowing in the motor, and a controller that controls the motor based on the current value.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to a semiconductor manufacturing apparatus used for wire bonding.

Background Art

[0002] Patent Document 1 discloses a technique for fixing a lead frame with a jig of a metal plate when performing wire bonding in the process of manufacturing a semiconductor device. Only the expansion and contraction force of a spring was used for fixing this lead frame.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above method, the fixing force cannot be varied so as to compensate for manufacturing errors such as warping and undulation of the lead frame. Also, when the spring deteriorates over time, the fixing force weakens. As described above, when the lead frame cannot be fixed with a constant force during wire bonding, there is a problem that quality defects occur.

[0005] In order to solve the above problems, an object of the present disclosure is to provide a semiconductor device capable of performing stable wire bonding by equalizing the fixing torque by motor control when fixing a lead frame with a jig.

Means for Solving the Problems

[0006] Aspects of the present disclosure preferably relate to a semiconductor manufacturing apparatus including a lower jig having a mounting surface for a lead frame on an upper surface thereof, an upper jig positioned in an upper surface direction of the lower jig, a ball screw for fixing the upper jig, a motor for rotating the ball screw to sandwich the lead frame with the lower jig and the upper jig, a current measuring device for measuring a current value flowing through the motor, and a controller for controlling the motor based on the current value.

Advantages of the Invention

[0007] Aspects of the present disclosure include a lower jig having a mounting surface for a lead frame on an upper surface thereof, an upper jig positioned in an upper surface direction of the lower jig, a ball screw for fixing the upper jig, a motor for rotating the ball screw to sandwich the lead frame with the lower jig and the upper jig, a current measuring device for measuring a current value flowing through the motor, and a controller for controlling the motor based on the current value The controller includes a first setting means for determining a first set value, and a first control means for stopping the motor when the current value reaches the first set value. preferably relate to a semiconductor manufacturing apparatus.

Brief Description of the Drawings

[0008]

Figure 1

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[0009] Embodiment 1 First, we will explain wire bonding using metal wire. Figure 1 shows the operating section of wire bonding equipment. The wire bonding operating section includes a US horn 1. The US horn 1 is connected to a capillary 2, which is configured to feed out a metal wire 3. The metal wire 3 is made of a metal with low electrical resistance, such as gold, silver, copper, or aluminum.

[0010] The first process of wire bonding is a spark action that forms a fabricated adhesive (FAB) at the tip of the metal wire. For example, a spark rod 5 discharges electricity toward the tip of the metal wire 3, melting the tip of the metal wire 3 and forming a fabricated adhesive (FAB) 4.

[0011] 2 is a diagram showing a portion of a semiconductor device in which metal wires are wired. A semiconductor element 6 is bonded to a lead frame 8 using a die bond adhesive 7. The semiconductor element 6 can be, for example, an IC element having a length of 3.5 mm or less, a width of 7 mm or less, and a thickness of 0.5 mm or less. A fabricated adhesive (FAB) 4a is bonded to the semiconductor element 6, and a metal wire 3a having the FAB 4a at its tip is connected to a lead frame 8a.

[0012] The second process of wire bonding is the operation of bonding the fabricated object to the electrodes of the semiconductor element. For example, in the case of the semiconductor device shown in Figure 2, the fabricated object 4 is first moved to a predetermined position by vertical movement of the capillary 2 in the Z direction and reciprocal movement in the X and Y directions. Then, the fabricated object 4 is pressed against the semiconductor element 6 and ultrasonic waves (US) are applied at the same time, thereby forming a fabricated object 4a bonded to the semiconductor element 6.

[0013] 3 shows the operation of the capillary for forming the metal wire. A metal wire 3a is bonded via a fabrication backplane 4a onto a semiconductor element 6. The position where a metal wire 3b will be wired via a fabrication backplane 4b is indicated by a dashed line.

[0014] Furthermore, the path that must be taken by the capillary 2 to form the wiring of the metal wire 3b is shown by a dotted line as a trajectory image 11. That is, the metal wire 3b is wired at the position of the dashed line in the following manner. First, after the FAB 4b is formed on the semiconductor element 6, the capillary 2 is operated as shown in the trajectory image 11. Then, the capillary 2 is moved above the power semiconductor element 13, which will be described later, and the metal wire 3b is joined.

[0015] The third process of wire bonding is the operation of forming a metal wire wiring with the fab at its tip. For example, in the case of the semiconductor device shown in Figure 3, after completing bonding of the fab 4b, the capillary 2 repeats minute movements in the Z direction and the X and Y directions, as shown in the trajectory image 11. As a result, when the metal wire 3b is bonded to the power semiconductor element 13 at the end opposite the fab 4b in a later process, the wiring of the metal wire 3b is formed as shown by the dashed line. Note that the space 12 indicates the space existing between the trajectory image 11 and the metal wire 3a, and indicates that the tip of the capillary 2 follows a path that does not collide with other wiring.

[0016] 4 is a diagram showing a portion of a semiconductor device wired with multiple metal wires. Multiple metal wires, such as metal wire 3a with FAB 4a at its tip and metal wire 3b with FAB 4b at its tip, are bonded to a semiconductor element 6. Metal wire 3a is bonded to lead frame 8a at one end opposite FAB 4a. Metal wire 3b is bonded to power semiconductor element 13 at one end opposite FAB 4b. Power semiconductor element 13 is bonded to lead frame 8b with a bonding material (not shown).

[0017] The fourth process of wire bonding is the operation of joining the opposite end of the metal wire with the FAB at the tip. For example, in the case of the semiconductor device shown in Figure 4, once the formation of the metal wire 3b is complete, the capillary 2 moves to a predetermined position on the power semiconductor element 13. Then, by pressing the metal wire 3b against the power semiconductor element 13 and simultaneously applying US, the metal wire 3b can be joined to the power semiconductor element 13. The above four steps are an overview of the wire bonding process.

[0018] Fig. 5 is a diagram showing an example of the shape of a lead frame. As described above, a semiconductor element 6 is bonded to a lead frame 8 via a die bond adhesive 7. When the lead frame 8 has a complex shape as shown in Fig. 5, in order to perform stable wire bonding, each bonding point of the lead frame 8 needs to be fixed with a certain force when bonding the metal wire 3.

[0019] FIG. 6 is a diagram showing an overall view of an open state of a lead frame holding jig according to Embodiment 1 of the present disclosure. The lead frame holding jig includes a lower jig 14. A ball screw 16 passes through the lower jig 14, and the tip of the ball screw 16 is fixed to an upper jig 15. The ball screw 16 operates by a motor 17 to move the upper jig 15 up and down to open and close a gap with the lower jig 14. Further, a current measuring device 18 is connected to the motor 17. A controller 19 is connected to the current measuring device 18, and the clamp load can be set to an arbitrary value. Although not shown, a controller is connected to the current measuring device 18.

[0020] When the lead frame 8 is conveyed between the lower jig 14 and the upper jig 15, the motor 17 operates and the lead frame 8 is clamped. At this time, the current measuring device 18 monitors the current value flowing through the motor 17 and transmits the value to the controller. The controller determines a set value of the current value based on the clamp load set in advance by the controller 19. When the current value reaches the set value, the motor 17 is controlled to stop the operation of the ball screw.

[0021] Advantages of the control by current value monitoring include high accuracy. In the motor 17, current always flows with respect to the load. Therefore, when the load applied to the motor 17 changes, the flowing current value also changes. Since the current value changes even with a slight load fluctuation, by monitoring the current value, the load condition applied to the motor 17 can be detected sensitively. For this reason, highly accurate control is possible by monitoring the current value.

[0022] Further, the lead frame holding jig in FIG. 6 has an advantage that it can be easily configured. The motor 17 can be realized by, for example, a stepping motor or a servo motor, and these are easily available. Also, the current measuring device 18 is easily available as a commercially available product. Therefore, the lead frame holding jig shown in FIG. 6 can be easily configured by using an existing lead frame holding jig.

[0023] Note that although the configuration in which the controller 19 is joined is shown here, a configuration in which the controller 19 is not connected may be used as long as the setting of the clamp load is not changed. Further, for the purpose of stabilizing the bonding strength of wire bonding, the lower jig 14 may be configured to include a heater.

[0024] FIG. 7 is a diagram showing an overall view of the closed state of the lead frame presser jig according to Embodiment 1 of the present disclosure. According to the method of fixing the lead frame 8 by the above-described method, the lead frame 8 can be fixed with a constant force without being affected by the warpage or undulation of the lead frame 8 and without being affected by the spring deterioration of the semiconductor device. Therefore, the reproducibility of wire bonding is improved and the stability is enhanced.

[0025] FIG. 8 is a flowchart of the lead frame fixing operation according to Embodiment 1. In this flowchart, the operations in the modes shown in FIGS. 6 and 7 will be described. First, in step 100, the lead frame 8 is mounted on the semiconductor device. Next, in step 102, the lead frame is transported to the regions of the lower jig 14 and the upper jig 15.

[0026] Subsequently, in step 104, the upper jig 15 is lowered by the operation of the motor 17 via the ball screw 16. As a result, as in step 106, the upper jig 15 comes into contact with the lead frame. Then, as in step 108, a change occurs in the current value of the motor 17.

[0027] In step 110, the current value is monitored using the current measuring device 18. Then, the clearance amount between the upper jig 15 and the lower jig 14 is converted from the current value, and the motor 17 is stopped when the clearance amount reaches the clearance amount specified by the controller 19. Thereby, the lead frame 8 is fixed while maintaining the specified clearance amount. Thereafter, wire bonding is performed as in step 112.

[0028] The purpose of ensuring the clearance amount is as follows. First, in the lead frame 8 with a thickness of less than 0.75 mm, if the fixing torque is too large, deflection will occur. Therefore, by ensuring a certain clearance amount, it is possible to suppress the deflection and improve the reproducibility of wire bonding. Also, in the lead frame 8 with a thickness of 0.75 mm or more, if the fixing torque is too large, excessive oxidation of the lead frame due to heat will occur. Therefore, by ensuring a certain clearance amount, it is possible to suppress the oxidation and improve the stability of wire bonding.

[0029] Figure 9 is a flowchart of the lead frame fixing operation according to a modification of Embodiment 1. Embodiment 1 is an aspect including the controller 19, but in this flowchart, the operation in the aspect without the controller 19 is described as a modification. Since steps 100 to 108 are common to FIG. 8, the description thereof is omitted.

[0030] In step 114, the current value is monitored using the current measuring device 18, and the motor 17 is stopped when a specific value is reached. Thereby, the lead frame 8 is fixed with a certain force. Then, wire bonding is performed as in step 116.

[0031] Embodiment 2 Figure 10 is a flowchart of the lead frame fixing operation according to Embodiment 2. The configuration of the device in Embodiment 2 is the same as that in Embodiment 1, but the flow of the fixing operation is different. Embodiment 2 is used, for example, when the lead frame 8 has a complex shape as shown in FIG. 5. In this case, even if wire bonding is performed with the same weight applied to the whole by the upper jig 15, there is a problem that the fixing torque for each area of the lead frame 8 does not become constant due to the influence of its own manufacturing error and conveyance accuracy. Therefore, first, the optimum torque for fixing is set in advance for each area of the lead frame 8. Then, each time the area where wire bonding is to be performed moves, the lead frame 8 is fixed again with a different fixing torque. Thereby, wire bonding can be performed in a state of being fixed with a weight suitable for that area.

[0032] The specific procedure for the fixing operation will be described below. Steps 100 to 112 are the same as those in Figure 8, so their explanation will be omitted. In step 118, the upper jig 15 is first raised to release the lead frame 8. Then, the upper jig 15 is lowered again to apply the set load to the area of the lead frame 8 where wire bonding will be performed next. This fixes the lead frame 8 again with the load optimal for the next wire bonding. Then, in step 120, wire bonding is performed at the relevant location. By repeating this process, the lead frame 8 can be fixed with the appropriate torque for each area where wire bonding will be performed, even if the lead frame 8 has a complex shape.

[0033] Embodiment 3 11 is a flowchart of the lead frame fixing operation according to the third embodiment. In addition to the configuration of the first embodiment, the third embodiment includes a heater for heating the lower jig 14. Heating the lead frame 8 with the heater of the lower jig 14 has the advantage of stabilizing the bonding strength of the wire bonding, but has the problem of thermal expansion since the lead frame 8 is made of copper. Therefore, by applying a load and then releasing it, the deflection of the expanded lead frame 8 is released and then the lead frame 8 is fixed again.

[0034] A specific procedure for the fixing operation will be described. Steps 100 to 110 are the same as those in Fig. 8, so the description will be omitted. First, prior to step 100, in step 121, the heater provided in the lower jig 14 is heated. Subsequently, the processing from steps 100 to 110 is performed.

[0035] Next, in step 122, the upper jig 15 is raised to release the lead frame 8 that has been fixed for a certain period of time. This releases any deflection of the lead frame 8 due to thermal expansion. Then, in step 124, the upper jig 15 is lowered to fix the lead frame 8 again. Then, as in step 126, the upper jig 15 comes into contact with the lead frame 8, and as in step 128, a change occurs in the current value of the motor 17.

[0036] Subsequently, in step 130, the current value is monitored using the current measuring device 18. Then, the clearance amount between the upper jig 15 and the lower jig 14 is converted from the current value, and the motor 17 is stopped when the clearance amount reaches the clearance amount specified by the controller 19. Thereby, the lead frame 8 is fixed while maintaining the specified clearance amount. Thereafter, wire bonding is performed as in step 132.

[0037] Note that the clearance amount when fixing for the first time in step 110 and the clearance amount when fixing for the second time in step 130 may be the same value or different values.

Explanation of Reference Numerals

[0038] 8 Lead frame 8a Lead frame 8b Lead frame 14 Lower jig 15 Upper jig 17 Motor 18 Current measuring device

Claims

1. A lower jig having a mounting surface for a lead frame on its upper surface, an upper jig positioned in the upper surface direction of the lower jig, a ball screw for fixing the upper jig, a motor that rotates the ball screw and sandwiches the lead frame with the lower jig and the upper jig, a current measuring device that measures the current value flowing through the motor, a controller that controls the motor based on the current value comprising, the controller has a first setting means for determining a first set value, and a first control means for stopping the motor when the current value reaches the first set value A semiconductor manufacturing apparatus.

2. The controller, for each predetermined area of the lead frame the first setting means determines the first set value, and the first control means stops the motor when the current value reaches the first set value corresponding to the predetermined area. The semiconductor manufacturing apparatus according to claim 1.

3. The lower jig has a heater, the controller subsequent to the first control means, has a releasing means for rotating the ball screw to increase the distance between the upper jig and the lower jig, a second setting means for determining a second set value, and a second control means for stopping the motor when the current value reaches the second set value The semiconductor manufacturing apparatus according to claim 1.

4. A semiconductor manufacturing method using a semiconductor manufacturing apparatus comprising a lower jig having a mounting surface for a lead frame on its upper surface, an upper jig positioned in the upper surface direction of the lower jig, a ball screw for fixing the upper jig, a motor that rotates the ball screw and sandwiches the lead frame with the lower jig and the upper jig, a current measuring device that measures the current value flowing through the motor, and a controller that controls the motor based on the current value comprising: a sandwiching process of rotating the ball screw and sandwiching the lead frame with the upper jig and the lower jig, a measuring process of measuring the current value flowing through the motor with the current measuring device, a control process of controlling the motor based on the current value, comprising, the control process has a first setting process for determining a first set value, and a first stopping process for stopping the motor when the current value reaches the first set value A semiconductor manufacturing method.

5. The control process, for each predetermined area of the lead frame, in the setting process, determines the first set value, and in the stopping process, stops the motor when the current value reaches the first set value corresponding to the predetermined area. The semiconductor manufacturing method according to claim 4, wherein the control process is repeated by the number of the predetermined areas.

6. A semiconductor manufacturing method using the semiconductor manufacturing apparatus of claim 3, comprising: a heat treatment for heating the heater; a clamping process of rotating the ball screw and clamping the lead frame with the upper jig and the lower jig; a measurement process of measuring a current value flowing through the motor with the current measuring device; a first setting process of determining a first set value; a first stop process of stopping the motor when the current value reaches the first set value; a release process of rotating the ball screw and increasing the distance between the upper jig and the lower jig; a second setting process of determining a second set value; a second stop process of stopping the motor when the current value reaches the second set value; A semiconductor manufacturing method comprising the above.

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