Semiconductor manufacturing device

Abstract

To obtain a semiconductor manufacturing device that can improve productivity.SOLUTION: A wire bonding device 1 executes wire bonding of applying ultrasonic vibration to join a wire 2 to a semiconductor chip 3. A vibration measuring unit 11 measures the frequency of the ultrasonic vibration in the wire bonding. A control section 10 stops the wire bonding device 1 when the frequency is smaller than a first threshold, and causes the wire bonding device 1 to execute re-wire bonding to the semiconductor chip 3 without stopping the wire bonding device when the frequency is equal to or more than the first threshold and smaller than a second threshold.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a semiconductor manufacturing apparatus that performs wire bonding using ultrasonic vibrations. [Background technology]

[0002] When manufacturing a semiconductor device, a semiconductor chip and a lead frame are connected by wires. However, during wire bonding, bonding defects such as peeling of the wires may occur due to foreign matter, improper device settings, or variations in materials. Currently, bonding defects are detected by visual inspection by personnel or by energizing. This requires a large amount of man-hours and impedes production. There are also concerns about the effect on the semiconductor chip if energizing is performed for inspection after wire bonding. In response to this, it has been proposed to detect vibrations during wire bonding, compare them with a reference value, and stop the device if an abnormality is determined (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-264597 Summary of the Invention [Problem to be solved by the invention]

[0004] Even if a bonding failure occurs, if the ball at the tip of the wire is not removed, it is possible to re-bond the wire. Conventionally, even in such a case, it was judged as an abnormality, the device was stopped temporarily, and the condition of the wire tip was checked visually or by image processing. As a result, there was a problem of low productivity.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a semiconductor manufacturing apparatus capable of improving productivity. [Means for solving the problem]

[0006] The semiconductor manufacturing apparatus according to the present disclosure is characterized in that it comprises a wire bonding device that performs wire bonding by applying ultrasonic vibrations to join a wire to a semiconductor chip, a vibration measuring device that measures the frequency of the ultrasonic vibrations of the wire bonding, and a control unit that stops the wire bonding device if the frequency is smaller than a first threshold value, and performs re-wire bonding on the semiconductor chip without stopping the wire bonding device if the frequency is equal to or greater than the first threshold value and smaller than a second threshold value. Effect of the Invention

[0007] In the present disclosure, the frequency of ultrasonic vibrations for wire bonding is measured, and if the frequency is smaller than a first threshold, the wire bonding device is stopped. If the frequency is equal to or greater than the first threshold and smaller than a second threshold, re-wire bonding is performed on the semiconductor chip without stopping the wire bonding device. This can improve productivity. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing a semiconductor manufacturing apparatus according to a first embodiment. [Diagram 2] FIG. 2 is a side view showing the arrangement of vibration measuring instruments according to the first embodiment. [Diagram 3] FIG. 4 is a cross-sectional view showing a state after wire bonding. [Figure 4] FIG. 2 is an enlarged cross-sectional view showing a state of wire bonding. [Diagram 5] 3 is a flowchart of a wire bonding method according to the first embodiment. [Figure 6] 1 is a perspective view showing a wire bonding method according to a first embodiment. [Figure 7] 1 is a perspective view showing a wire bonding method according to a first embodiment. [Figure 8] 1 is a perspective view showing a wire bonding method according to a first embodiment. [Figure 9]1 is a perspective view showing a wire bonding method according to a first embodiment. [Figure 10] 1 is a perspective view showing a wire bonding method according to a first embodiment. [Figure 11] FIG. 11 is a side view showing the arrangement of vibration measuring devices according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A semiconductor manufacturing apparatus according to an embodiment will be described with reference to the drawings. The same or corresponding components are designated by the same reference numerals, and repeated description may be omitted.

[0010] Embodiment 1 1 is a diagram showing a semiconductor manufacturing apparatus according to embodiment 1. Wire bonding apparatus 1 performs wire bonding by applying ultrasonic vibration to bond wire 2 to semiconductor chip 3. Wire bonding apparatus 1 has a fixing jig 4, a wire supplying apparatus 5, a capillary 6 that extends wire 2, a vibrating ultrasonic transducer 7, and an ultrasonic horn 8 that transmits vibration of ultrasonic transducer 7 to capillary 6.

[0011] A semiconductor chip 3 and the like are mounted on a fixing jig 4. A predetermined amount of wire 2 is supplied from a wire supply device 5 and guided to the tip of a capillary 6 by a wire guide 9. The wire 2 is a thin metal wire of gold, silver, copper, aluminum, or the like, with a diameter of, for example, about 25 μm. The capillary 6 is attached to the tip of an ultrasonic horn 8. An ultrasonic transducer 7 is attached to the base of the ultrasonic horn 8. The ultrasonic transducer 7 converts electrical energy supplied from a control unit 10 into vibrational energy and vibrates ultrasonically.

[0012] Capillary 6 applies ultrasonic vibrations to bond wire 2 to semiconductor chip 3. Semiconductor chip 3 is a rectangular IC element with short sides of 3.5 mm or less. For example, semiconductor chip 3 has 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. In the case of such a small semiconductor chip 3, it is preferable that wire 2 has a diameter of 50 μm or less.

[0013] A vibration measuring device 11 measures the vibration frequency of the ultrasonic horn 8. A processing circuit 12 amplifies the output voltage of the vibration measuring device 11 and samples and holds the peak voltage to obtain a detection signal. A control unit 10 compares the detection signal with a threshold value. Depending on the comparison result, an alarm device 13 notifies the operator of the bonding status by turning on a bonding OK display or a warning light or by emitting a warning sound.

[0014] 2 is a side view showing the arrangement of the vibration measuring instrument according to the first embodiment. The vibration measuring instrument 11 is arranged adjacent to the ultrasonic horn 8, and measures the vibration of the ultrasonic horn 8 to measure the vibration frequency per unit time of the ultrasonic vibration of the wire bonding. It is preferable that the vibration measuring instrument 11 is arranged adjacent to the tip of the ultrasonic horn 8, and measures the vibration of the tip of the ultrasonic horn 8. This allows any abnormality in the vibration transmitted to the wire 2 to be measured with high accuracy.

[0015] The vibration measuring device 11 is, for example, a laser Doppler vibrometer, a laser displacement meter, a piezoelectric element, or the like. These are readily available. The laser Doppler vibrometer measures the vibration of the ultrasonic horn 8 by utilizing the Doppler effect of a laser. The laser displacement meter irradiates the ultrasonic horn 8 with a laser beam, detects the displacement of the ultrasonic horn 8 by the reflected beam, and measures the vibration of the ultrasonic horn 8. The piezoelectric element is a piezoelectric element that generates a voltage when pressure is applied. The piezoelectric element is a factor that inhibits ultrasonic vibration because it contacts the ultrasonic horn 8 to measure the vibration of the ultrasonic horn 8, but it is possible to perform highly accurate measurement. The inhibition of ultrasonic vibration can be reduced by contacting the piezoelectric element with the base of the ultrasonic horn 8 instead of the tip.

[0016] 3 is a cross-sectional view showing the state after wire bonding. A lead frame 14 and a semiconductor chip 3 are mounted on a fixing jig 4. The lead frame 14 has a die pad 15 and lead terminals 16. A control semiconductor chip 3 is bonded onto the die pad 15 with a die bond adhesive 17. The pads of the semiconductor chip 3 and the lead terminals 16 are connected by wires 2. Note that the pads of the semiconductor chip 3 may be wire-connected to pads of other semiconductor chips.

[0017] 4 is an enlarged cross-sectional view showing the wire bonding process. A ball 18 (FAB: Free Air Ball) is formed at the tip of the wire 2 extending from the tip of the capillary 6. The ball 18 is heated to approximately 200 to 240°C and ultrasonic vibrations are applied while a load is applied to the ball 18 by the capillary 6, thereby thermocompressing the ball 18 to the pad of the semiconductor chip 3. In this way, the wire bonding device 1 applies ultrasonic vibrations to bond the ball 18 at the tip of the wire 2 to the semiconductor chip 3. Bonding the ball 18 at the tip of the wire 2 to something is called ball bonding.

[0018] Fig. 5 is a flowchart of the wire bonding method according to embodiment 1. Figs. 6 to 10 are perspective views showing the wire bonding method according to embodiment 1. First, the lead frame 14 and the semiconductor chip 3 are mounted on a fixing jig 4 (step S1).

[0019] Next, as shown in Fig. 6, discharge is applied from the spark rod 19 toward the tip of the wire 2 extending from the tip of the capillary 6. When the tip of the wire 2 melts due to the discharge, it becomes round due to surface tension. The rounded tip of the wire 2 is solidified as it is to form a ball 18 (step S2). This is called a spark operation.

[0020] 7, the ball 18 at the tip of the wire 2 is pressed against the pad of the semiconductor chip 3 and ultrasonic vibration is applied to bond the wire (step S3). At this time, the vibration measuring device 11 measures the vibration of the ultrasonic horn 8 to measure the number of vibrations per unit time of the ultrasonic vibration during wire bonding (step S4).

[0021] If the measured frequency is smaller than the first threshold, the control unit 10 determines that an abnormality has occurred and stops the wire bonding apparatus 1. Then, the bonding state of the wire 2 and the state of the wire tip are checked visually or by image processing, and the spark operation is repeated if necessary. If the measured frequency is equal to or greater than the first threshold and smaller than the second threshold, the control unit 10 causes the wire bonding apparatus 1 to perform wire bonding again on the semiconductor chip 3 without stopping the wire bonding apparatus 1 (step S5). If the measured frequency is equal to or greater than the second threshold, the control unit 10 determines that the ball bond has been performed normally.

[0022] Here, the frequency of ultrasonic vibrations during wire bonding and the bonding state are sampled in advance by experiments or the like. The lower limit of the frequency when wire bonding is performed normally is set as the second threshold value. The lower limit of the frequency when wire bonding is not performed normally but the ball 18 at the tip of the wire 2 is not removed is set as the first threshold value. The second threshold value is larger than the first threshold value.

[0023] If the ball bond is performed normally, the control unit 10 causes the ultrasonic horn 8 to repeatedly perform fine movements in the Z direction and the XY direction to perform looping to shape the wire 2 so that it can be shaped into a desired trajectory, as shown in FIG. 8. Next, the control unit 10 controls the wire bonding apparatus 1 to press the other end of the wire 2 against the bonding surface of the lead terminal 16 and apply ultrasonic vibration to perform stitch bonding, as shown in FIG. 9. The other end of the wire 2 may be bonded to a pad of another semiconductor chip 3. Thereafter, the tail of the wire 2 is cut, as shown in FIG. 10. The above wire bonding process is performed on multiple wires 2 in the manufacture of a semiconductor device.

[0024] As described above, in this embodiment, the frequency of ultrasonic vibrations for wire bonding is measured, and if the frequency is smaller than the first threshold, it is likely that the ball 18 at the tip of the wire 2 has come off, and the wire bonding apparatus 1 is stopped. This makes it possible to detect wire bonding defects and suppress the occurrence of defective products. Also, if the frequency is equal to or greater than the first threshold and smaller than the second threshold, it can be determined that the ball 18 at the tip of the wire 2 has not come off, and re-wire bonding is performed on the semiconductor chip 3 without stopping the wire bonding apparatus 1. This makes it possible to improve productivity. As a result, the profit margin is also improved.

[0025] Embodiment 2 FIG. 11 is a side view showing the arrangement of a vibration measuring instrument according to the second embodiment. In this embodiment, the vibration measuring instrument 11 is attached to the lower surface of the fixing jig 4. The vibration measuring instrument 11 measures the vibration of the fixing jig 4 to measure the frequency of ultrasonic vibration for wire bonding. The vibration measuring instrument 11 is, for example, a laser Doppler vibrometer, a laser displacement meter, a piezoelectric element, or the like. In the first embodiment, the vibration measuring instrument 11 is arranged adjacent to the ultrasonic horn 8, and therefore the vibration measuring instrument 11 may interfere with the wire bonding operation. In contrast, in this embodiment, the vibration measuring instrument 11 does not interfere with the wire bonding operation. The vibration measuring instrument 11 may be arranged on the side surface or upper surface of the fixing jig 4 instead of the lower surface. The other configurations and effects are the same as those of the first embodiment.

[0026] Although the preferred embodiments have been described above in detail, the present disclosure is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims. Various aspects of the present disclosure are described below as appendices. (Appendix 1) a wire bonding apparatus for performing wire bonding by applying ultrasonic vibration to bond a wire to a semiconductor chip; a vibration measuring device for measuring the frequency of the ultrasonic vibration of the wire bonding; a control unit that stops the wire bonding device when the vibration frequency is smaller than a first threshold value, and that performs re-wire bonding on the semiconductor chip without stopping the wire bonding device when the vibration frequency is equal to or greater than the first threshold value and smaller than a second threshold value. (Appendix 2) 2. The semiconductor manufacturing apparatus according to claim 1, wherein the wire bonding apparatus applies ultrasonic vibration to bond a ball at the tip of the wire to the semiconductor chip. (Appendix 3) When the vibration frequency is smaller than the first threshold value, the ball at the tip of the wire is removed, The semiconductor manufacturing apparatus according to claim 2, characterized in that when the vibration frequency is greater than or equal to the first threshold value and less than the second threshold value, the ball at the tip of the wire is not removed. (Appendix 4) The semiconductor manufacturing apparatus of any one of appendices 1 to 3, wherein when the vibration frequency is equal to or greater than the second threshold value, the control unit controls the wire bonding device to join the other end of the wire to a lead terminal or another semiconductor chip. (Appendix 5) The wire bonding apparatus includes a capillary for extending the wire, an ultrasonic transducer for vibrating, and an ultrasonic horn for transmitting vibration of the ultrasonic transducer to the capillary, 4. The semiconductor manufacturing apparatus according to claim 1, wherein the vibration measuring device measures a frequency of ultrasonic vibration for the wire bonding by measuring vibration of the ultrasonic horn. (Appendix 6) The capillary is attached to the tip of the ultrasonic horn, 6. The semiconductor manufacturing apparatus according to claim 5, wherein the vibration measuring device measures vibrations at a tip of the ultrasonic horn. (Appendix 7) the wire bonding apparatus has a fixture on which the semiconductor chip is mounted, 4. The semiconductor manufacturing apparatus according to claim 1, wherein the vibration measuring device measures a frequency of ultrasonic vibration for the wire bonding by measuring vibration of the fixing jig. (Appendix 8) 4. The semiconductor manufacturing apparatus according to claim 1, wherein the vibration measuring device is a laser Doppler vibrometer. (Appendix 9) 4. The semiconductor manufacturing apparatus according to claim 1, wherein the vibration measuring device is a laser displacement meter. (Appendix 10) 4. The semiconductor manufacturing apparatus according to claim 1, wherein the vibration measuring device is a piezoelectric element. (Appendix 11) 4. The semiconductor manufacturing apparatus according to claim 1, wherein the semiconductor chip is a rectangle having a short side of 3.5 mm or less. (Appendix 12) 4. The semiconductor manufacturing apparatus according to claim 1, wherein the wire has a diameter of 50 μm or less. [Explanation of symbols]

[0027] REFERENCE SIGNS LIST 1 wire bonding device, 2 wire, 3 semiconductor chip, 4 fixing jig, 6 capillary, 7 ultrasonic transducer, 8 ultrasonic horn, 10 control unit, 11 vibration measuring device, 16 lead terminal, 18 ball

Claims

1. a wire bonding apparatus for performing wire bonding by applying ultrasonic vibration to bond a wire to a semiconductor chip; a vibration measuring device for measuring the frequency of the ultrasonic vibration of the wire bonding; a control unit that stops the wire bonding device when the vibration frequency is smaller than a first threshold, and that performs re-wire bonding on the semiconductor chip without stopping the wire bonding device when the vibration frequency is equal to or greater than the first threshold and smaller than a second threshold.

2. 2. The semiconductor manufacturing apparatus according to claim 1, wherein the wire bonding apparatus applies ultrasonic vibration to bond a ball at the tip of the wire to the semiconductor chip.

3. When the vibration frequency is smaller than the first threshold value, the ball at the tip of the wire is removed, 3. The semiconductor manufacturing apparatus according to claim 2, wherein when the vibration frequency is equal to or greater than the first threshold value and smaller than the second threshold value, the ball at the tip of the wire is not removed.

4. A semiconductor manufacturing apparatus as described in any one of claims 1 to 3, characterized in that when the vibration frequency is greater than or equal to the second threshold value, the control unit controls the wire bonding device to join the other end of the wire to a lead terminal or another semiconductor chip.

5. The wire bonding apparatus includes a capillary for extending the wire, an ultrasonic transducer for vibrating, and an ultrasonic horn for transmitting vibration of the ultrasonic transducer to the capillary, 4. The semiconductor manufacturing apparatus according to claim 1, wherein the vibration measuring device measures the frequency of the ultrasonic vibration for the wire bonding by measuring the vibration of the ultrasonic horn.

6. The capillary is attached to the tip of the ultrasonic horn, 6. The semiconductor manufacturing apparatus according to claim 5, wherein said vibration measuring device measures vibration of a tip of said ultrasonic horn.

7. the wire bonding apparatus has a fixture on which the semiconductor chip is mounted, 4. The semiconductor manufacturing apparatus according to claim 1, wherein the vibration measuring device measures the frequency of the ultrasonic vibration for the wire bonding by measuring the vibration of the fixing jig.

8. 4. The semiconductor manufacturing apparatus according to claim 1, wherein the vibration measuring device is a laser Doppler vibrometer.

9. 4. The semiconductor manufacturing apparatus according to claim 1, wherein the vibration measuring device is a laser displacement meter.

10. 4. The semiconductor manufacturing apparatus according to claim 1, wherein the vibration measuring device is a piezoelectric element.

11. 4. The semiconductor manufacturing apparatus according to claim 1, wherein the semiconductor chip is rectangular with a short side of 3.5 mm or less.

12. 4. The semiconductor manufacturing apparatus according to claim 1, wherein the wire has a diameter of 50 μm or less.

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