JP2023121542A - Semiconductor manufacturing equipment and method for manufacturing semiconductor - Google Patents

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

The present disclosure relates to semiconductor manufacturing equipment used for wire bonding.

Patent Literature 1 discloses a technique of fixing a lead frame with a metal plate jig when performing wire bonding in the process of manufacturing a semiconductor device. Only the elastic force of the spring was used to fix the lead frame.

JP 2001-015544 A

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

In order to solve the above-described problem, the present disclosure aims to provide a semiconductor device capable of stable wire bonding by equalizing the fixing torque through motor control when fixing a lead frame with a jig.

An aspect of the present disclosure includes a lower jig having a lead frame mounting surface on its upper surface, an upper jig positioned in the upper surface direction of the lower jig, a ball screw to which the upper jig is fixed, and a rotating ball screw. , a semiconductor manufacturing apparatus comprising a motor for clamping a lead frame between a lower jig and an 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. preferable.

According to an aspect of the present disclosure, it is possible to provide a semiconductor device capable of stable wire bonding by equalizing fixing torque by motor control when fixing a lead frame with a jig.

FIG. 3 is a diagram showing the working part of the wire bonding equipment; It is a figure which shows a part of semiconductor device with which the metal wire was wired. FIG. 4 illustrates the operation of capillaries for shaping metal wire; 1 is a diagram showing a part of a semiconductor device wired by a plurality of metal wires; FIG. It is a figure which shows an example of the shape of a lead frame. FIG. 4 is a diagram showing an overall image of the open state of the lead frame holding jig according to the first embodiment of the present disclosure; FIG. 4 is a diagram showing an overview of a closed state of the lead frame pressing jig according to the first embodiment of the present disclosure; 4 is a flow chart of lead frame fixing operation according to the first embodiment. 7 is a flow chart of lead frame fixing operation according to a modification of the first embodiment; 10 is a flow chart of lead frame fixing operation according to the second embodiment. 10 is a flow chart of a lead frame fixing operation according to Embodiment 3;

Embodiment 1
First, wire bonding of metal wires will be described. FIG. 1 is a diagram showing the working part of a wire bonding equipment. A wire-bonding operation unit includes a US horn 1 . A US horn 1 is connected to a capillary 2, and the capillary 2 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, aluminum, or the like.

The first process of wire bonding is the spark action that causes the FAB to form on the tip of the metal wire. For example, the FAB 4 can be formed by discharging from the spark rod 5 toward the tip of the metal wire 3 to melt the tip of the metal wire 3 .

FIG. 2 is a diagram showing a part of a semiconductor device in which metal wires are wired. A semiconductor element 6 is bonded to the lead frame 8 using a die bonding material 7 . As the semiconductor element 6, an IC element having a vertical dimension of 3.5 mm or less, a horizontal dimension of 7 mm or less, and a thickness of 0.5 mm or less can be exemplified. A FAB 4a is joined to the semiconductor element 6, and a metal wire 3a having the FAB 4a at its tip is connected to a lead frame 8a.

The second process of wire bonding is the operation of bonding the FAB to the electrodes of the semiconductor element or the like. For example, in the case of the semiconductor device shown in FIG. 2, the FAB 4 is first moved to a predetermined position by vertically moving the capillary 2 in the Z direction and reciprocating in the XY directions. By pressing the FAB 4 against the semiconductor element 6 and simultaneously applying ultrasonic waves (US), the FAB 4a bonded to the semiconductor element 6 can be formed.

FIG. 3 shows the operation of a capillary for shaping metal wire. A metal wire 3a is bonded onto the semiconductor element 6 via the FAB 4a. A dashed line indicates a position where the metal wire 3b is to be routed through the FAB 4b.

Furthermore, a path that the capillary 2 must pass through to form wiring of the metal wire 3b is indicated by a dotted line as a trajectory image 11. FIG. That is, the metal wire 3b is routed at the position indicated by the broken line by the following method. First, after the FAB 4 b is formed on the semiconductor element 6 , the capillary 2 is moved like the trajectory image 11 . After that, the capillary 2 is moved above the power semiconductor element 13, which will be described later, and the metal wire 3b is joined.

The third process of wire bonding is the operation of forming metal wire traces with FAB tips. For example, in the case of the semiconductor device shown in FIG. 3, the capillary 2 after bonding the FAB 4b repeats minute movements in the Z and XY directions as shown in the trajectory image 11 . As a result, when the metal wire 3b is joined to the power semiconductor element 13 at one end on the opposite side of the FAB 4b in a later process, the wiring of the metal wire 3b is formed as indicated by the dashed line. A space 12 indicates a space existing between the trajectory image 11 and the metal wire 3a, and indicates that the tip of the capillary 2 passes through a path that does not collide with other wires.

FIG. 4 is a diagram showing part of a semiconductor device wired by a plurality of metal wires. A plurality of metal wires such as a metal wire 3a having an FAB 4a at its tip and a metal wire 3b having a FAB 4b at its tip are bonded onto the semiconductor element 6. As shown in FIG. The metal wire 3a is joined to the lead frame 8a at one end opposite to the FAB 4a. The metal wire 3b is joined to the power semiconductor element 13 at one end opposite to the FAB 4b. The power semiconductor element 13 is bonded onto the lead frame 8b with a bonding material (not shown).

The fourth wire bonding process is the act of bonding one end of the metal wire on the opposite side to the FAB. For example, in the case of the semiconductor device shown in FIG. 4, the capillary 2 moves to a predetermined position above the power semiconductor element 13 after the formation of the metal wire 3b is completed. The metal wire 3b can be joined to the power semiconductor element 13 by pressing the metal wire 3b against the power semiconductor element 13 and simultaneously applying US. The above four are the outline of the wire bonding process.

FIG. 5 is a diagram showing an example of the shape of the lead frame. As described above, the semiconductor element 6 is bonded to the lead frame 8 via the die bonding material 7 . When the lead frame 8 has a complicated shape as shown in FIG. 5, in order to perform stable wire bonding, each joint of the lead frame 8 is fixed with a constant force when the metal wire 3 is joined. There is a need.

FIG. 6 is a diagram showing an overall image of the open state of the lead frame holding jig according to Embodiment 1 of the present disclosure. The lead frame holding jig has 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 the upper jig 15 . The ball screw 16 is operated by a motor 17 to move the upper jig 15 up and down to open and close the gap with the lower jig 14 . A current measuring device 18 is also connected to the motor 17 . A controller 19 is connected to the current measuring device 18, and the clamp weight can be set to an arbitrary value. Although not shown, the current measuring device 18 is connected to a controller.

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 value of the current flowing through the motor 17 and transmits the value to the controller. The controller determines the set current value based on the clamp weight previously set by the controller 19 . Then, when the current value reaches the set value, the motor 17 is controlled to stop the operation of the ball screw.

An advantage of control based on current value monitoring is high accuracy. In the motor 17, current always flows to the load. Therefore, when the load applied to the motor 17 changes, the value of the flowing current also changes. Since the current value changes even with a slight change in the load, the load condition applied to the motor 17 can be sensitively detected by monitoring the current value. Therefore, highly accurate control is possible by monitoring the current value.

Moreover, there is an advantage that the lead frame holding jig of FIG. 6 can be easily configured. The motor 17 can be implemented by, for example, a stepping motor or a servomotor, which are readily available. Moreover, the current measuring device 18 is also readily available on the market. Therefore, the lead frame holding jig shown in FIG. 6 can be easily constructed by utilizing the existing lead frame holding jig.

Although a configuration in which the controller 19 is connected is shown here, a configuration in which the controller 19 is not connected may be used if the setting of the clamp load is not changed. Further, the lower jig 14 may be provided with a heater for the purpose of stabilizing the bonding strength of wire bonding.

FIG. 7 is a diagram illustrating an overall image of a closed state of the lead frame holding 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 warp or undulation of the lead frame 8 or by the deterioration of the spring of the semiconductor device. can be fixed. Therefore, the reproducibility of wire bonding is enhanced and the stability is improved.

FIG. 8 is a flow chart of the lead frame fixing operation according to the first embodiment. This flow chart describes the operation in the mode shown in FIGS. First, in step 100, the lead frame 8 is mounted on the semiconductor device. Next, in step 102, the lead frame is conveyed to the lower jig 14 and upper jig 15 areas.

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

At step 110 , the current value is monitored using the current meter 18 . Then, the amount of clearance 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 specified by the controller 19 is reached. As a result, the lead frame 8 is fixed while maintaining the specified clearance. Wire bonding is then performed as in step 112 .

There are two purposes for ensuring the clearance amount. First, in the lead frame 8 having a thickness of less than 0.75 mm, deflection occurs when the fixing torque is too large. Therefore, by ensuring a certain amount of clearance, it is possible to suppress deflection and improve the reproducibility of wire bonding. Also, if the lead frame 8 has a thickness of 0.75 mm or more, if the fixing torque is too large, the lead frame will be excessively oxidized due to heat. Therefore, by securing a certain amount of clearance, it is possible to suppress oxidation and improve the stability of wire bonding.

FIG. 9 is a flowchart of lead frame fixing operation according to the modification of the first embodiment. Although the first embodiment is a mode with the controller 19, this flowchart describes the operation in a mode without the controller 19 as a modified example. Since steps 100 to 108 are the same as those in FIG. 8, their explanation is omitted.

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. The lead frame 8 is thereby fixed with a constant force. Wire bonding is then performed as in step 116 .

Embodiment 2
FIG. 10 is a flow chart of the lead frame fixing operation according to the second embodiment. Embodiment 2 is similar to Embodiment 1 in device configuration, but differs in the flow of fixing operation. The second embodiment is used, for example, when the lead frame 8 has a complicated shape as shown in FIG. In this case, even if wire bonding is performed while the same weight is applied to the whole by the upper jig 15, the fixed torque for each area of the lead frame 8 is not constant due to the influence of manufacturing errors and transportation accuracy. There is Therefore, the optimum torque for fixing is set in advance for each area of the lead frame 8 . Then, each time the wire bonding area is moved, the lead frame 8 is fixed again with a different fixing torque. As a result, wire bonding can be performed in a state in which a weight suitable for the area is fixed.

A specific fixing operation procedure will be described. Since steps 100 to 112 are the same as those in FIG. 8, their explanation is omitted. In step 118, first, the upper jig 15 is lifted to release the lead frame 8 once. Then, the upper jig 15 is lowered again in order to apply the set weight to the area of the lead frame 8 to be wire-bonded next. The lead frame 8 is thereby fixed again with the optimum weight for the next wire bonding. After that, in step 120, wire bonding is performed at the corresponding locations. By repeating this, even if the lead frame 8 has a complicated shape, it is possible to fix the lead frame 8 with an appropriate torque for each area to be wire-bonded.

Embodiment 3
FIG. 11 is a flow chart of lead frame fixing operation according to the third embodiment. The third embodiment includes a heater for heating the lower jig 14 in addition to the configuration of the first embodiment. Heating the lead frame 8 with the heater of the lower jig 14 has the advantage of stabilizing the bonding strength of wire bonding, but has the problem of thermal expansion since the lead frame 8 is made of copper. Therefore, by releasing the lead frame 8 once after applying a weight, the bending of the expanded lead frame 8 is relieved and then fixed again.

A specific fixing operation procedure will be described. Since steps 100 to 110 are the same as those in FIG. 8, their explanation is 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.

Next, in step 122, the upper jig 15 is lifted to release once the lead frame 8 fixed for a certain period of time. Here, the deflection due to thermal expansion of the lead frame 8 is relieved. Then, in step 124, the upper jig 15 is lowered to fix the lead frame 8 again. Then, the upper jig 15 comes into contact with the lead frame 8 as shown in step 126 and the current value of the motor 17 changes as shown in step 128 .

Subsequently, in step 130, the current value is monitored using the current measuring device 18. FIG. Then, the amount of clearance 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 specified by the controller 19 is reached. As a result, the lead frame 8 is fixed while maintaining the specified clearance. Wire bonding is then performed as in step 132 .

The clearance amount for the first fixation in step 110 and the clearance amount for the second fixation in step 130 may be the same value or different values.

8 lead frame 8a lead frame 8b lead frame 14 lower jig 15 upper jig 17 motor 18 current measuring device

Claims (8)

a lower jig having a lead frame mounting surface on its upper surface;
an upper jig positioned above the lower jig;
a ball screw to which the upper jig is fixed;
a motor that rotates the ball screw and clamps the lead frame between the lower jig and the upper jig;
a current measuring device for measuring the value of the current flowing through the motor;
A semiconductor manufacturing apparatus comprising: a controller that controls the motor based on the current value. The controller is
a first setting means for determining a first set value;
2. The semiconductor manufacturing apparatus according to claim 1, further comprising first control means for stopping said motor when said current value reaches said first set value. the controller determines the first set value by the first setting means for each predetermined area of the lead frame;
The first control means stops the motor when the first set value corresponding to the predetermined area is reached.
3. The semiconductor manufacturing apparatus according to claim 2. the lower jig has a heater,
the controller
release means for rotating the ball screw to increase the distance between the upper jig and the lower jig, following the first control means;
a second setting means for determining a second set value;
3. The semiconductor manufacturing apparatus according to claim 2, further comprising second control means for stopping said motor when said current value reaches said second set value. A semiconductor manufacturing method using the semiconductor manufacturing apparatus of claim 1,
a clamping process of rotating the ball screw and clamping the lead frame between 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 control process for controlling the motor based on the current value;
A semiconductor manufacturing method comprising: The control process includes
a first setting process for determining a first set value;
6. The semiconductor manufacturing method according to claim 5, further comprising a first stop process of stopping said motor when said current value reaches said first set value. The control process includes, for each predetermined area of the lead frame,
In the setting process, the first set value is determined;
In the stop processing, when the first set value corresponding to the predetermined area is reached, the motor is stopped;
7. The semiconductor manufacturing method according to claim 6, wherein said control processing is repeated by the number of said predetermined areas. A semiconductor manufacturing method using the semiconductor manufacturing apparatus of claim 4,
a heat treatment for heating the heater;
a clamping process of rotating the ball screw and clamping the lead frame between 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 for determining a first set value;
a first stop process for stopping the motor when the current value reaches the first set value;
a releasing process of rotating the ball screw to increase the distance between the upper jig and the lower jig;
a second setting process for determining a second set value;
a second stop process for stopping the motor when the current value reaches the second set value;
A semiconductor manufacturing method comprising:

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