Mounting apparatus and method for semiconductor devices

Abstract

To bond a semiconductor chip to a substrate or the like with high position accuracy.SOLUTION: A semiconductor chip before pickup is imaged with a first camera from above so that the positional relation between the outer shape of the chip and the pattern is stored. Next, the chip is picked up beyond the collet with a bonding tool. After that, the outer shape of the chip is imaged from above with a second camera and the pattern position after the pickup is stored as first data from the data of the pattern position imaged before the pickup and the outer shape imaged after the pickup. Moreover, the mount position is minutely adjusted based on second data obtained by imaging the substrate with the second camera and the first data to perform bonding.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for mounting semiconductor devices. [Background technology]

[0002] There are mounting devices and methods for bonding semiconductor chips onto circuit boards. These mounting devices and methods bond the circuit board, which is the lower object to be bonded, and the semiconductor chip, which is the upper object to be bonded, after aligning their positions. Semiconductor chips include LD (laser diode), LED, CMOS, and SAW (surface acoustic wave) devices. In recent years, with the miniaturization of electronic devices, the dimensions of semiconductor chips have become as small as about 0.3 mm square, and as a result, there is a demand for the accuracy of alignment to be improved to the order of several μm.

[0003] As shown in FIG. 1, Patent Document 1 describes a mounting device in which first, a chip pattern 31 such as the outline of the chip 3 and alignment marks is image-recognized from the top surface of a semiconductor chip 3 by a first camera 121 (data A in FIG. 1(a)), then the chip is picked up by a bonding tool 161 and the outline of the chip is image-recognized from the back surface of the chip by a second camera 122 (data B in FIG. 1(b)), data C of the relative position of the mark with respect to the outline of the picked up chip is calculated based on data A and data B, and image recognition data D of the substrate 5 obtained by a third camera 123 shown in FIG. 1(c) is obtained, and the relative positions of the chip and substrate are corrected based on data C and D to perform die bonding (FIG. 1(d)). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-133340 A Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the positional relationship between the chip outline and the alignment mark is calculated before picking up, and the mark position after picking up can be calculated from the outline recognition from the back side after the chip is picked up, so there is an advantage that the alignment with the substrate can be performed with high accuracy. However, since the position of the alignment mark on the front side is calculated from the chip outline imaged from the back side of the chip after picking up, if the edge of the chip is oblique as shown in FIG. 2(b), the calculated positional relationship between the outline from the back side and the alignment mark may be misaligned. Therefore, further improvement in accuracy is an issue. In addition, if there is unevenness 35 caused by chipping during blade dicing as shown in FIG. 2(a), the shape of the edge differs between the front and back sides of the chip 3, and the positional relationship between the edge and the mark cannot be calculated accurately. In addition, three cameras are required: a camera for imaging the chip before picking up, a camera for imaging the chip from the bottom after picking up, and a camera for imaging the substrate, so there is also the issue that the device becomes complicated and the cost increases.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to realize a semiconductor mounting device that has a simple configuration and is capable of highly accurate alignment. [Means for solving the problem]

[0007] In order to solve the above problems, the semiconductor mounting device of the present invention is a mounting device having a chip pick-up mechanism having a first camera that images a semiconductor chip from above before it is picked up, a bonding head that adsorbs the semiconductor chip so that it protrudes from the head, a second camera that images the substrate and the chip that protrudes from the bonding head from above, and a control unit that corrects the relative positions of the bonding head and the substrate from first data that calculates the relative positional relationship between the chip pattern and the end of the chip from an image of the semiconductor chip pattern obtained by the first camera and an image of the end of the chip that protrudes from the bonding head obtained by the second camera, and second data that represents the chip mounting position from an image of the substrate obtained by the second camera.

[0008] In addition to the above invention, it is preferable to have a bonding head in which the distance from the end face of the suction head to the suction hole is shorter than the distance from the center to the end of the semiconductor chip to be sucked.

[0009] In addition to the above invention, it is preferable that the tip of the collet of the suction head is tapered, and the width of the tip of the collet is smaller than the width of the semiconductor chip.

[0010] In addition to the above-mentioned invention, it is preferable that the collet is attached at an angle to the direction of vertical movement of the head, and the attachment angle is in the range of 20 degrees to 60 degrees.

[0011] In addition to the above-mentioned invention, it is preferable that the collet is made of a ceramic or metallic material.

[0012] Furthermore, a semiconductor device mounting method according to the present invention is a semiconductor device mounting method using the mounting apparatus, and is characterized in that it sequentially includes a chip surface image recognition step of imaging the semiconductor chip from above before picking up and recognizing the outer shape of the semiconductor chip end and the pattern of the semiconductor chip, a pick-up step of adsorbing the semiconductor chip with a bonding head so that the semiconductor chip protrudes from the bonding head and picking it up, a substrate image recognition step of imaging the substrate from above and calculating the mounting position of the semiconductor chip, a chip end image recognition step of imaging the end of the semiconductor chip protruding above the bonding head, and a bonding step of correcting the relative positions of the semiconductor chip and the substrate based on first data obtained by calculating the relative positional relationship between the end of the chip in the picked-up state and the pattern obtained in the chip surface image recognition step and the chip end image recognition step and second data obtained in the substrate image recognition step that indicates the chip mounting position on the substrate. Effect of the Invention

[0013] According to the present invention, it is possible to realize a semiconductor device mounting apparatus and a mounting method that are simple in configuration and capable of highly accurate mounting positioning. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram illustrating the operation of a mounting device according to a prior art example. [Diagram 2] 2A and 2B are schematic diagrams illustrating the top and side surfaces of a semiconductor chip to be mounted. [Diagram 3] 1A to 1C are explanatory diagrams showing how a wafer is processed into semiconductor chips. [Figure 4] FIG. 2 is a side view of a semiconductor chip to be mounted. [Diagram 5] 1 is a top view of a mounting apparatus according to an embodiment of the present invention; [Figure 6] FIG. 2 is a process flow diagram of a mounting method using the mounting apparatus according to the embodiment of the present invention. [Figure 7] FIG. 13 is a diagram showing the operation of the first camera. [Figure 8] FIG. 11 is an explanatory diagram for calculating a pattern position from a chip outer shape in the first data. [Figure 9] FIG. 13 is an explanatory diagram of how a chip is picked up. [Figure 10] FIG. 2 is a side view of a bonding tool. [Figure 11] 13 is a diagram showing the positional relationship between the chip and the bonding tool after the chip is picked up, as viewed from above. FIG. [Figure 12] 13 is an explanatory diagram showing how the chip after being picked up is imaged by the second camera. FIG. [Figure 13] FIG. 13 is an explanatory diagram of how the substrate is imaged by the second camera. [Figure 14] FIG. 1 is an explanatory diagram of alignment between a chip and a substrate. [Figure 15] FIG. 2 is an explanatory diagram of a state in which a chip and a substrate are die-bonded. [Figure 16] FIG. 1 shows a chip with diagonal dicing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] First, the semiconductor chip 3 mounted by the semiconductor device mounting apparatus will be described with reference to FIGS.

[0016] Fig. 2(a) is a top view of a semiconductor chip 3 to be bonded by a semiconductor device mounting apparatus 1. A device pattern 31 is formed on the chip 3. After a large number of device patterns are formed on a semiconductor wafer 32, the chip is placed on a dicing sheet (not shown) as shown in Fig. 3 and cut out by dicing to become individual chips 3.

[0017] Dicing methods include blade dicing, laser dicing, stealth dicing, etc. In the most common blade dicing method, as shown in FIG. 3, a dicing blade 41 physically cuts a wafer 32 by grinding.

[0018] If the dicing blade is perpendicular to the wafer during dicing, the chip cut surface will be perpendicular to the pattern surface, and there will be no misalignment between the front and back edge positions of the chip. However, if the parallelism of the wafer or the perpendicularity of the dicing blade during dicing is not correct, the chip edges will be slanted, as shown in Figures 2(b) and 4. As shown in Figure 4, the amount of misalignment d between the top and bottom edges of the edges at this time is expressed as follows, where t is the thickness of chip 3 and A is the angle: d=t / tan A This is expressed as:

[0019] Here, when the chip thickness t is 100 μm and the cutting angle A of the dicing blade is 89°, the deviation width d is ≈ 1.8 μm. As in Patent Document 1, the position of the chip outline obtained from the back surface of the chip 3 and the pattern 31 are misaligned on the order of microns. This causes a significant position error in a mounting device that aims for an accuracy of several μm for a small chip.

[0020] Furthermore, during blade dicing, it is unavoidable that unevenness 35 due to chipping will occur in the cut portion of the chip 3, as shown in Figure 2. Since chipping occurs randomly, the shape of the edges will differ between the front and back surfaces of the chip 3. Furthermore, the position of the unevenness 35 will be irregular depending on the chip.

[0021] Next, the mounting device of the present invention will be described with reference to FIG.

[0022] FIG. 5 is a top view of the mounting device of the present invention. The pickup unit 11 delivers the chip 3 from the diced wafer 32 to the bonding head 61. Above the pickup unit 11, there is a first camera 21, which takes an image of the chip 3 before it is picked up. The bonding head 61 is attached to an x-axis moving rail 62 via a z-axis moving mechanism 63, and can move in the zx direction. The mounting unit 12 is located at the destination of the bonding head 61. Above the mounting unit 12, there is a second camera 22, which can take an image of the substrate 5 held by the substrate stage 13. After the bonding head 61 moves to the mounting unit 12, the second camera 22 can take an image of the chip 3 adsorbed to the bonding head 61 from above. The mounting unit 12 has a substrate stage 13, which holds the substrate 5. The substrate stage 13 has a function of being able to move slightly in the xyθ direction. Furthermore, the bonding head 61 is equipped with a mechanism 63 that can move up and down in the z direction, and can bond the chip 3 to the substrate 5.

[0023] The details of an actual bonding device and a bonding method will be described with reference to the process diagram of FIG. 6 and FIGS.

[0024] [Step S1] First, one chip 3 placed on the pickup unit 11 is imaged by the first camera 21 as shown in FIG. 7, and the image is stored as a first image in a control unit (not shown). At this time, the chip 3 is adhered to the dicing sheet 33, the dicing sheet is expanded, and the chips are arranged apart from each other. The focus of the first camera 21 is adjusted to the chip surface, and unevenness 35 caused by chipping on the chip outer shape is also recorded. This first image is aligned with the second image obtained in step S4 to contribute to the creation of the first data.

[0025] [Step S2] Next, the chip 3 is picked up from the dicing sheet 33 by a bonding head 61 shown in FIG.

[0026] Here, the bonding head 61 is attached to a vertical (z-axis) moving mechanism 63, and the moving mechanism 63 is attached to a rail 62 as shown in Fig. 10. Therefore, the bonding head 61 can move freely in the x- and z-axis directions.

[0027] As shown in Fig. 10, the bonding head 61 is composed of a support part 65 and a collet 66, and has a suction port 64 inside the head. The distance s from the tip of the collet 66 to the center of the suction port 64 is smaller than the distance p from the chip end to the chip center. Because of this, when the chip 3 is picked up, it can be sucked so that it protrudes from the bonding head 61, as shown in Fig. 11. By sucking the chip 3 so that it protrudes from the bonding head 61 when it is picked up, the external shape of the chip 3 can be imaged from above in the next process.

[0028] 11, the collet 66 is tapered toward the tip, and the narrowest tip is smaller than the width of the tip 3. This ensures that the tip 3 protrudes from the collet. This allows the external shape of the tip 3 to be reliably imaged from above in the next process.

[0029] Furthermore, the collet 66 is attached at an angle to the z-axis as shown in Fig. 10. This makes it possible to observe three sides of the chip 3 as shown in Fig. 11. The attachment angle β in this case is preferably from 20° to 60°. This is because if the angle β is small, the protruding portion of the chip 3 cannot be observed sufficiently, and if the angle β is large, the collet becomes too tilted, making it difficult for the collet to adsorb and hold the chip.

[0030] To realize such a collet 66, the material of the collet 66 is preferably a ceramic material or a metal material. In order to suck up a chip with a side of 1 mm or less in a protruding state, the collet must be processed to dimensions on the order of sub-mm, and a suction port must also be made. Ceramics and metal materials are suitable for this processing, and it is difficult to make a glass material. If a bonding head can be made using a transparent material such as glass, it may be possible to image the chip from above without taking a manufacturing method such as reducing the dimensions of the collet and attaching it at an angle as in this embodiment. However, since it is difficult to make a collet that can accommodate a microchip of 1 mm or less using a glass material, it can be said that in the present invention, it is suitable to make the collet from a ceramic or metal material.

[0031] [Step S3] Next, the second camera 22 captures an image of the substrate 5 as shown in Fig. 13. From the captured image, the control unit calculates the mounting position of the chip 3 on the substrate 5 and stores it as second data. Step S6 may be performed simultaneously with steps S1, S2, or S3. By performing them simultaneously, the process time until chip mounting can be shortened.

[0032] [Step S4] The bonding head 61 that picked up the chip 3 moves along the rail 62 in the x-axis direction and stops under the second camera 22. The second camera 22 captures an image of the protruding portion of the chip 3 from above the bonding tool 61 as shown in FIG. 12, and saves the image as a second image. When capturing the image, the focus of the second camera is adjusted to the chip surface. This allows the outer edge shape of the chip surface to be recognized along with the irregularities 35 caused by chipping.

[0033] [Step S5] The external shape of the chip 3 obtained from the first image obtained in step S1 is pattern matched with the external shape of the chip 3 obtained from the second image obtained in step S4. The positional relationship between the chip external shape obtained in the first image and the pattern 31 is calculated and combined with the matched external shape data, so that the chip pattern position after picking up can be calculated (FIG. 8). This pattern position data after picking up is stored as first data in a control unit (not shown).

[0034] When the first data is created from the imaging data from the bottom surface (back surface) of the chip as in Patent Document 1, the first data is the positional relationship between the chip end and the pattern obtained from the imaging data from the top surface of the chip, and the position of the chip end on the back surface obtained from the second camera is shifted on the order of μm, and as a result, the second data has an error on the order of μm. In addition, the positions of the unevenness 35 caused by chipping are different on the front and back surfaces of the chip 3, and the shapes of the edge parts are different on the front and back surfaces, which also become an error factor. By installing the second camera on the top surface of the chip as in this embodiment and imaging the chip end from the top surface, an image of the edge shape same as the first data can be obtained, and therefore data of the pattern position with extremely little error, i.e., the first data, can be obtained. In addition, in order to reliably image the chip end surface from the top surface of the chip, it is also important that the chip 3 is adsorbed so that it protrudes from the bonding head 61 as shown in FIG. 11.

[0035] The device of Patent Document 1 requires three cameras to capture images of the chips and board: one to capture images of the chip before it is picked up, one to capture images of the chip from below after it is picked up, and one to capture images of the board. In contrast, the mounting device of this invention requires only one camera to capture images of the board and the chip from above, so two cameras are sufficient. This simplifies the structure of the mounting device, and reduces costs.

[0036] [Step S6] Next, based on the first data and the second data, the substrate stage 13 is slightly moved in the x, y, and θ directions relative to the chip 3 to align it (FIG. 14). This alignment can be performed not only by the stage, but also by providing the movement mechanism on the bonding head side with an x, y, and θ direction position adjustment mechanism, so that alignment can be performed on the head side. Alternatively, a combination is also possible, where alignment in the x and y directions is performed on the bonding head side, and alignment in the θ direction is performed on the substrate stage side.

[0037] When the picked-up chip is imaged from the backside and calculations are performed, the calculation results for the pattern position relative to the outer shape in step S5 may deviate by 1 μm or more, as mentioned above. In contrast, when the picked-up chip is imaged from above, as in this device, the pattern position can be known accurately, allowing for highly accurate alignment.

[0038] [Step S7] After the alignment in step S6 is completed, the bonding head is lowered in the -z direction to die-bond the chip 3 onto the substrate 5, as shown in FIG.

[0039] Once step S8 is complete, the process returns to step S1 and is repeated. The direction of the cut side of the end of the chip 3 may become slanted during dicing, as shown in Figure 16. Also, unevenness caused by chipping during dicing differs for each chip. From the image captured in step S1, the positional relationship between the edge shape and the pattern can be calculated even when the chip edge is slanted or chipping has occurred, so by repeating from S1, even chips that have been cut at an angle and have chipping can be bonded with high precision.

[0040] This step S1 can be performed simultaneously with step S7. By performing S1 and S7 simultaneously, the total process time can be shortened.

[0041] As described above, by using this apparatus and the die bonding method using this apparatus, chip 3 can be mounted on substrate 5 with a simple configuration and high positional accuracy on the order of microns.

[0042] The present invention is not limited to the above-described embodiment, and any modifications or improvements that can achieve the object of the present invention are included in the present invention. For example, the present invention can be used for mounting electronic components other than semiconductor chips and other mechanical components. [Explanation of symbols]

[0043] 1. Semiconductor device mounting equipment 11 Pickup section 12 Mounting section 13 Substrate stage 121 First Camera 122 Second Camera 123 The Third Camera 161 Bonding Head 21 First Camera 22 Second Camera 3. Semiconductor chips 32 Semiconductor Wafers 33 Dicing sheet 35 Unevenness caused by chipping 41 Dicing Blade 5 Substrate 61 Bonding Head 62 x-axis moving rail 63 z-axis movement mechanism 64 Suction port 65 Bonding head support 66 Colette

Claims

1. A mounting apparatus for die-bonding a semiconductor chip to a predetermined position on a substrate, a chip pick-up mechanism having a first camera for picking up an image of a semiconductor chip from above; a bonding head having a collet at its tip and adsorbing a semiconductor chip so that the chip appears to protrude when viewed from above; a second camera for capturing an image of the substrate and the semiconductor chip protruding from the bonding head from above; A mounting device having a control unit that corrects the relative positions of the bonding head and substrate from first data calculated from a pattern image of a semiconductor chip obtained by a first camera and an image of the end of the semiconductor chip protruding from the bonding head obtained by a second camera, and second data representing the chip mounting position from an image of the substrate obtained by the second camera.

2. 2. The mounting device according to claim 1, The collet is a mounting device in which the distance from the tip to the center of the suction port is shorter than the distance from the center to the edge of the semiconductor chip to be sucked.

3. In the mounting device according to claim 1 or 2, The tip of the collet is tapered, A mounting device in which the width of the tip of the collet is smaller than the width of the semiconductor chip.

4. In the mounting device according to any one of claims 1 to 3, The collet is attached at an angle to the vertical movement direction of the bonding head, The mounting angle of the mounting device is between 20 and 60 degrees.

5. The mounting device according to any one of claims 1 to 4, The collet is made of a ceramic or metallic material.

6. A semiconductor device mounting method for die-bonding a semiconductor chip to a predetermined position on a substrate using the mounting apparatus according to any one of claims 1 to 5, comprising the steps of: a chip surface image recognition step of capturing an image of the semiconductor chip from above before picking up the semiconductor chip and recognizing an end portion and a pattern of the semiconductor chip; a pick-up step of picking up the semiconductor chip by suction so that the semiconductor chip appears to protrude from the bonding head when viewed from above by the bonding head; a substrate image recognition step of imaging the substrate from above and calculating the mounting position of the semiconductor chip; and a chip end image recognition step of imaging an end of the semiconductor chip protruding above the bonding head. a bonding step of performing die bonding by correcting the relative positions of the semiconductor chip and the substrate based on first data obtained by calculating the relative positional relationship between the end of the chip in a picked-up state and a pattern, which is obtained in the chip surface image recognition step, and second data representing the chip mounting position on the substrate, which is obtained in the substrate image recognition step.

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