JP7522621B2 - Focus adjustment method, focus adjustment tool, die bonding device, and method for manufacturing semiconductor device - Google Patents

Description

This disclosure relates to a focus adjustment tool and can be applied, for example, to a die bonder that adjusts the focus of a recognition camera.

Part of the manufacturing process for semiconductor devices is the process of placing semiconductor chips (hereinafter simply referred to as dies) on wiring boards or lead frames (hereinafter simply referred to as substrates) to assemble a package, and part of the process of assembling the package is the process of dividing the die from a semiconductor wafer (hereinafter simply referred to as wafers) (dicing process) and the bonding process of placing the divided die on the substrate. The semiconductor manufacturing equipment used in the bonding process is a die bonding device such as a die bonder.

For example, in a die bonder that bonds a die to the surface of a substrate, the following operation (task) is repeated: a suction nozzle called a collet is attached to the tip of the bonding head to pick up the die from the wafer, the die is placed in a predetermined position on the substrate fixed to the bond stage, and a pressing force is applied while the bonding material is heated to bond the die.

In addition, in a die bonder, for example, an imaging device is attached near the bonding head, and this imaging device is used to confirm the position of the substrate to which the die is bonded, determine positioning, and also to confirm that the bonded die is bonded in the specified position.

JP 2019-175888 A

In order to improve the positioning accuracy or inspection accuracy described above, it is necessary to improve the focus adjustment accuracy of the imaging device.

The objective of this disclosure is to provide technology that can improve the focus adjustment accuracy of an imaging device.

A brief summary of representative aspects of this disclosure is given below.
That is, the focus adjustment jig is for adjusting the distance between an object to be imaged placed on the stage and an imaging device located above the object to be imaged so that the object to be imaged is located at the focus of the imaging device, and is placed on the stage. The focus adjustment jig includes a first jig having a patterned surface on which a pattern is provided and which is set at a first predetermined angle with an upper surface of the stage, and a second jig having a mirror surface on which a mirror is provided and which is set at a second predetermined angle with the upper surface of the stage and which is set at an angle of 90 degrees with the patterned surface. The mirror surface of the focus adjustment jig is configured to be imaged by the imaging device.

This disclosure makes it possible to improve the focus adjustment accuracy of an imaging device.

FIG. 1 is a perspective view showing a scale jig for adjusting the focus. FIG. 2 is a diagram showing an example of an image and brightness when the pattern on the patterned surface shown in FIG. 1 is imaged. FIG. 3 is a diagram for explaining a method of measuring the focal position using the scale jig shown in FIG. FIG. 4 is a diagram for explaining the configuration of an optical system of a general device. FIG. 5 is a diagram for explaining a problem with the method of measuring the focal position using the scale jig shown in FIG. FIG. 6 is a diagram showing a focus adjustment jig in the embodiment. FIG. 7 is a schematic diagram for explaining the operation of the focus adjustment jig shown in FIG. FIG. 8 is a side view showing the focus adjustment jig in the first modified example. FIG. 9 is a side view showing a focus adjustment jig in the second modified example. FIG. 10 is a side view showing a focus adjustment jig in the third modified example. FIG. 11 is a side view showing a focus adjustment jig in the fourth modified example. FIG. 12 is a diagram showing a focus adjustment jig in the fifth modified example. FIG. 13 is a diagram showing a focus adjustment jig in the sixth modified example. FIG. 14 is a side view of an apparatus according to the seventh modified example. FIG. 15 is a diagram showing a focus adjustment jig in the eighth modified example. FIG. 16 is a top view showing an outline of the die bonder in the embodiment. FIG. 17 is a diagram for explaining the operation of the pickup head and the bonding head when viewed from the direction of the arrow A in FIG. FIG. 18 is a schematic cross-sectional view showing a main part of the die supply unit shown in FIG. FIG. 19 is a block diagram showing a schematic configuration of a control system of the die bonder shown in FIG. FIG. 20 is a flow chart showing a method for manufacturing a semiconductor device using the die bonder shown in FIG.

The following describes the embodiments, modifications, and examples with reference to the drawings. However, in the following description, the same components are given the same reference numerals and repeated description may be omitted. Note that in the drawings, the width, thickness, shape, etc. of each part may be shown diagrammatically compared to the actual embodiment in order to make the description clearer, but these are merely examples and do not limit the interpretation of this disclosure.

First, the technology investigated by the present inventors will be explained using Figures 1 to 5.

A method for adjusting the focus of an optical system that captures an image of a workpiece placed on a stage using an imaging device equipped with a lens is described with reference to Figure 1. Figure 1 is a perspective view of a scale jig for adjusting the focus. Figure 1(a) is a diagram showing a scale jig with a patterned surface that is inclined with respect to the optical axis. Figure 1(b) is a diagram showing a scale jig with a patterned surface that is installed perpendicular to the optical axis.

The present inventors have investigated a method of imaging a scale jig 201 placed on a stage 103 using an imaging device 101 as shown in FIG. 1, and adjusting the focus based on the captured image. The scale jig 201 has a patterned surface 201a on a plane inclined with respect to the optical axis OA as shown in FIG. 1(a), and a patterned surface 201a on a plane perpendicular to the optical axis as shown in FIG. 1(b). Each patterned surface 201a is printed with a pattern having straight lines parallel to the plane perpendicular to the optical axis, such as a striped pattern with clear edges, a checkered pattern, or a lattice pattern. The pattern is printed up to the bottom end of the patterned surface 201a of the scale jig 201 shown in FIG. 1(a). The height of the patterned surface 201a of the scale jig 201 shown in FIG. 1(b) is adjusted by a block gauge, a shim gauge, or the like.

The scale jig 201 shown in Fig. 1(a) has a pentahedral block shape consisting of a rectangular pattern surface 201a located on the front surface, a rectangular bottom surface, a rectangular back surface perpendicular to the bottom surface, and two triangular side surfaces. The scale jig 201 shown in Fig. 1(b) has a hexahedral plate shape consisting of a rectangular pattern surface 201a located on the top surface, a rectangular bottom surface, and four rectangular side surfaces perpendicular to the bottom surface.

The control unit (not shown) captures the pattern surface 201a with the imaging device 101, judges the contrast (light-dark difference) of the edge portion of the printed pattern from the captured image, and calculates the degree of deviation from the desired position. The control unit displays the calculated amount of deviation on a display device such as an LCD (Liquid Crystal Display). After that, based on the displayed amount of deviation, the worker adjusts the installation position of the imaging device 101, the installation position of the stage 103 on which the imaged object is placed, or the positional relationship between the lens 102 and the imaging surface (light receiving device surface) of the imaging device 101 to eliminate the deviation. The worker repeats this operation multiple times to adjust to the best focus position. Here, Hf is the height at which the focus is achieved.

Next, the method for measuring the in-focus position will be described in detail with reference to Figs. 2 and 3. Fig. 2 is a diagram showing an example of an image and brightness when the pattern on the pattern surface shown in Fig. 1 is imaged. Fig. 2(a) is a diagram showing the image when in focus, and Fig. 2(b) is a diagram showing the image when out of focus. Fig. 3 is a diagram explaining the method for measuring the in-focus position using the scale jig shown in Fig. 1(a). Fig. 3(a) is an image obtained of the pattern surface on the scale jig shown in Fig. 1(a), and Fig. 3(b) is a brightness difference graph of the pattern image shown in Fig. 3(a).

The control device calculates the contrast of the edge of the pattern from the pixel values of the image captured of the pattern surface 201a of the scale jig 201. As shown in Figure 2(a), when the pattern is in focus, the edge has a clear difference between light and dark. However, as shown in Figure 2(b), when the pattern is not in focus, the edge has a smoother difference between light and dark. In addition, the maximum/minimum brightness (brightness value) is large when the pattern is in focus, as shown in Figure 2(a), and is small when the pattern is not in focus, as shown in Figure 2(b). This occurs when the bleeding at the edge of a periodic pattern becomes larger than the period.

In the captured image shown in Figure 3(a), the contrast is clear near the center, and becomes less clear toward the ends. When the brightness value (BV), which is the pixel value of this captured image, is plotted, the brightness contrast graph shown in Figure 3(b) is obtained.

The contrast graph shown in FIG. 3(b) shows a larger difference as one approaches the best-focused position Pf and a smaller difference as one moves away. If it is possible to obtain graphs of the far side (left side of the graph) and the near side (right side of the graph) of the best-focused position as in the brightness difference graph shown in FIG. 3(b), the peak position can be clearly identified, and the depth of field (DOF) and best-focused position Pf can be accurately found. Here, let xf be the distance from the left end of pattern surface 201a to best-focused position Pf.

However, the scale jig 201 shown in FIG. 1(a) has the following problem. This problem will be explained using FIG. 4 and FIG. 5. FIG. 4 is a diagram explaining the configuration of the optical system of a general device. FIG. 4(a) is a diagram showing components arranged on a stage, and FIG. 4(b) is a diagram showing the scale jig arranged on the stage shown in FIG. 4(a). FIG. 5 is a diagram explaining the problem with the method of measuring the focal position using the scale jig shown in FIG. 1(a). FIG. 5(a) is an acquired image of the pattern surface of the scale jig shown in FIG. 4(b), and FIG. 5(b) is a brightness difference graph of the pattern image acquired from FIG. 5(a).

As shown in FIG. 4(a), when the imaging device 101 is attached to the base 301 of the device by the attachment member 302, the stage 103 must be adjusted so that the focus is on the height of the stage 103 plus the thickness of the member M as the object to be imaged. For example, a die bonding device is equipped with a stage 103 such as a bonding stage, an alignment stage, a pickup dome, and a preform stage. The stage 103 is focused on a position Po that takes into account the thickness (To) of the member M to be attached. The member M in the die bonding device is, for example, a wiring board, a lead frame, a die placed on a wiring board or a lead frame, or a die with a wafer attachment tape (dicing tape) attached. The thickness (To) of the member M is extremely thin, about several tens of μm to several mm. In other words, the height at which the focus is focused is the height near the top surface of the stage 103.

In addition, in die bonding devices, the above-mentioned stage 103 is structured to withstand the pressure of the attachment and is often fixed. The imaging device 101 is also often basically fixed in the height direction. Even if the imaging device 101 and stage 103 are fixed or movable, if the focus of the optical system cannot be finely adjusted on the stage 103 side to match the substrate transport surface, the focal position of the lens 102 attached to the imaging device 101 needs to be adjusted when attaching each unit (bonding unit, alignment unit, etc.) including the stage 103. The imaging device 101 is attached according to the design value. However, the focus adjustment and confirmation work of the lens 102 attached to the imaging device 101 needs to be actually confirmed by confirming the image captured by the imaging device 101 after attaching it to each unit.

An example of a method for checking the position where the focus is achieved will be described. First, as shown in FIG. 4(b), the scale jig 201 is placed on the stage 103. Here, it is sufficient that the pattern surface 201a is within the field of view VF of the imaging device 101, and it is not necessary to position the pattern surface 201a located at the center of the pattern surface 201a or at the height of the member M on the optical axis. Then, the control device captures the pattern surface 201a of the scale jig 201 using the imaging device 101 to obtain an image as shown in FIG. 3(a). Then, the control device obtains a graph of the brightness values from the pixel values of the obtained image along the arrow lines in the image as shown in FIG. 3(b). In the shade graph shown in FIG. 3(b), the brightness difference of the pattern increases and decreases from the center, and the position where this brightness difference is the largest can be said to be the position where the focus is achieved. Since this position needs to be determined from the graph, it is necessary to place the pattern of the pattern surface 201a at the height in front of and behind the position where the focus is achieved.

However, when the scale jig 201 is placed on the stage 103 for use in a die bonding device or the like, the height of the upper surface of the stage 103 is often fixed, as described above. In this case, even if an image of the pattern on the pattern surface 201a of the scale jig 201 shown in FIG. 4(b) is captured, only an image as shown in FIG. 5(a) can be captured. That is, the captured image has a clear contrast on the left side of the figure, and becomes unclear toward the right. Even if the contrast is measured based on the captured image shown in FIG. 5(a), it is often the case that only one half of the waveform of the grayscale graph as shown in FIG. 5(b) can be captured. That is, as shown in FIG. 5(b), the side closer to the imaging device 101 from the most focused position Pf can be measured, but the side farther from the imaging device 101 (the side indicated by the white arrow) cannot be measured. Such a measurement on only one side has a problem in that it cannot be determined with certainty that the place Pm with the largest drop in the brightness difference graph in FIG. 5(b) is the most focused position Pf.

In other words, it is difficult to determine whether the peak of the brightness difference is at the focusing position Po near the top surface of the stage 103, and it is difficult to determine whether the focus of the attached imaging device 101 is at the most adjusted position. Furthermore, if the peak of the brightness difference is farther (lower) than the top surface of the stage 103, it is not possible to measure how much the current positional relationship is misaligned. Here, the range in which the pattern of the scale jig 201 is provided is the measurable height range (Ha).

This problem is also solved by a method in which the scale jig 201 shown in FIG. 1(b) is placed on the stage 103, measurements are repeated while adjusting the height with a block gauge or the like, images of the pattern surface 201a are acquired, graphs of the contrast of the pattern image are sequentially obtained, and the focal position is found from the peak of the brightness difference.

Next, a focus adjustment jig in an embodiment that solves the above-mentioned problems will be described with reference to Figs. 6 and 7. Fig. 6 shows a focus adjustment jig in an embodiment, with Fig. 6(a) being a side view and Fig. 6(b) being a top view. Fig. 7 is a schematic diagram explaining the operation of the focus adjustment jig shown in Fig. 6.

The focus adjustment jig 200 in this embodiment is configured to obtain the opposite side of the brightness difference graph shown in FIG. 5 and obtain the brightness difference graph in the front and rear areas where focus is achieved. That is, the focus adjustment jig 200 is configured with a scale jig 201 as a first jig and a mirror jig 202 as a second jig.

The scale jig 201 shown in FIG. 6(a) has the same configuration as the scale jig 201 shown in FIG. 4(b). The patterned surface 201a has a pattern from the bottom end to the top end, but the upper part of the patterned surface 201a may be unpatterned.

As shown in FIG. 6(a), the mirror jig 202 is triangular in side view, and as shown in FIG. 6(b), it is rectangular in top view. The mirror jig 202 has a triangular prism-like pentahedral block shape consisting of a rectangular mirror surface 202a, a rectangular bottom surface, a rectangular back surface perpendicular to the bottom surface, and two triangular side surfaces. The mirror surface 202a is a flat surface inclined with respect to the optical axis OA as shown in FIG. 6(a), and is provided with a mirror that reflects light. The mirror surface 202a has a mirror from the bottom end to the top end, but the upper part of the mirror surface 202a does not need to be a mirror, and it is sufficient that the pattern is present up to the height where the pattern on the pattern surface 201a is present.

The patterned surface 201a of the scale jig 201 is a plane that forms a first angle (θ1) with respect to the upper surface of the stage 103. Here, 0 degrees < θ1 < 90 degrees. The mirror surface 202a of the mirror jig 202 is a plane that forms a second angle (θ2) with respect to the upper surface of the stage 103. Here, 0 degrees < θ2 < 90 degrees. The patterned surface 201a and the mirror surface 202a are perpendicular to each other. Here, it is preferable that the upper surface of the stage 103 is parallel to a horizontal plane. The scale jig 201 and the mirror jig 202 are installed on the stage 103 so that the mirror surface 202a of the mirror jig 202 is located opposite the patterned surface 201a of the scale jig 201. Here, the lower end of the patterned surface 201a and the lower end of the mirror surface 202a are in contact. As an example, the case where θ1 = θ2 = 45 degrees will be described below.

If the height of the mirror surface 202a and the pattern surface 201a is Ha, as shown in FIG. 7, the pattern surface 201a extends downward by Ha due to the virtual image of the pattern surface 201a reflected by the mirror surface 202a. As a result, by capturing an image of the pattern (virtual image) of the scale jig 201 reflected by the mirror surface 202a, a pattern image on the far side from the top surface of the stage 103 as seen from the imaging device 101, i.e., a brightness difference graph, can be obtained. A shading graph LS1 is obtained from a pattern image directly capturing the pattern surface 201a, and a shading graph LS2 is obtained from a pattern image captured by reflecting the pattern surface 201a by the mirror surface 202a. Here, the combination of the shading graph LS1 and the brightness difference graph LS2 corresponds to the shading graph shown in FIG. 3(b).

A method for adjusting the focus of the imaging device 101 using the focus adjustment jig 200 will be described. Here, the device having the imaging device 101 and the stage 103 is equipped with a control unit 300.

First, as shown in FIG. 6(a), the scale jig 201 and mirror jig 202 are placed on the stage 103. Here, it is sufficient that the patterned surface 201a and the mirror surface 202a are within the field of view VF of the imaging device 101, and it is not necessary to position the connection between the patterned surface 201a and the mirror surface 202a on the optical axis. Furthermore, it is not necessary for the entire patterned surface 201a and the mirror surface 202a to be within the field of view VF of the imaging device 101, and the upper parts of the patterned surface 201a and the mirror surface 202a do not have to be within the field of view VF of the imaging device 101.

Next, the control unit 300 captures the pattern surface 201a and mirror surface 202a of the scale jig 201 using the imaging device 101 to obtain an image with clear contrast between light and dark near the center, as shown in Figure 3(a).

Next, the control unit 300 determines the contrast of the edge of the printed pattern from the captured image and measures the focus position.

To explain in more detail, the control unit 300 obtains a graph of brightness values along the arrow lines in the image from the pixel values of the obtained image, as shown in FIG. 3(b), for example. In other words, the relationship between the position (x) on the pattern surface 201a and the brightness value (BV) is obtained.

As described above, in the shading graph shown in FIG. 3(b), the difference in brightness of the pattern increases and decreases from a peak in the center, and the control unit 300 determines that the position where the difference in brightness is greatest is the best-focused position Pf.

Then, the control unit 300 calculates the distance (xf) from the left end of the pattern surface 201a to the best focused position Pf. The control unit 300 then calculates the height Hf at which the focus is achieved from xf, as shown in FIG. 7. In the example shown in FIG. 7, Hf is located on the bottom surface of the focus adjustment jig 200, i.e., lower than the top surface of the stage 103.

The position of the peak brightness difference is preferably not simply found from the position of maximum contrast, but is instead calculated using a statistical approximation from the contrast before and after. This allows the focal position to be calculated more accurately. The accuracy of the approximation calculation is improved because data before and after the focal position can be obtained.

Next, the control unit 300 calculates how far the measured focal position is from the desired position.

The control unit 300 displays the calculated amount of deviation on a display device such as an LCD. The worker then adjusts the installation position of the imaging device 101, or the installation position of the stage 103 on which the subject is placed, or the positional relationship between the lens 102 and the imaging surface (light receiving device surface) of the imaging device 101 based on the displayed amount of deviation to eliminate the deviation. The worker repeats this operation multiple times to adjust to the best focus position. The imaging device 101 is attached to the base 301 via the mounting member 302, and the worker changes the mounting position of the mounting member 302 on the base 301, for example.

By using the focus adjustment jig 200, the amount of deviation in the focal position can be accurately measured after the imaging device 101 and stage 103 are installed. This improves the focus adjustment accuracy of the imaging device 101 and makes the adjustment work more efficient. Furthermore, improved focus adjustment accuracy can improve inspection sensitivity and positioning accuracy. Furthermore, more efficient adjustment work can reduce the labor required to manufacture the device.

<Modification>
Below, some representative modified examples of the embodiment are exemplified. In the following description of the modified examples, the same reference numerals as those in the above-mentioned embodiment may be used for parts having the same configuration and function as those described in the above-mentioned embodiment. The description of such parts may be appropriately cited within the scope of technical inconsistency. Furthermore, a part of the above-mentioned embodiment and all or a part of the modified examples may be appropriately applied in a composite manner within the scope of technical inconsistency.

(First Modification)
The focus adjustment jig in the first modified example will be described with reference to Fig. 8. Fig. 8 is a side view showing the focus adjustment jig in the first modified example.

In the focus adjustment jig 200 of the first modification, the mirror surface 202a of the mirror jig 202 and the pattern surface 201a of the scale jig 201 are not at 45 degrees to the top surface of the stage 103, but are perpendicular to each other. Here, the lower end of the pattern surface 201a and the lower end of the mirror surface 202a are in contact. The angle of the pattern surface 201a to the top surface of the stage 103 is θ1, and the angle of the mirror surface 202a is θ2. In the focus adjustment jig 200 of the first modification, as shown in FIG. 8, if θ1 is made smaller than θ2, that is, 0 degrees < θ1 < 45 degrees (45 degrees < θ2 < 90 degrees), the pitch of the pattern in the height direction becomes smaller, so that high-precision measurements can be made. By having an angle adjustment mechanism that allows the angle of the patterned surface 201a of the scale jig 201 and the mirror surface 202a of the mirror jig 202 to be selected at angles other than 45 degrees, the measurement accuracy of the measurement waveform of the brightness difference graph used to find the focus can be improved.

(Second Modification)
The focus adjustment jig in the second modified example will be described with reference to Fig. 9. Fig. 9 is a side view showing the focus adjustment jig in the second modified example.

In the second modified focus adjustment jig 200, as shown in FIG. 9, by making θ1 larger than θ2, i.e., 45 degrees < θ1 < 90 degrees (0 degrees < θ2 < 45 degrees), the height of the pattern becomes higher and the range of measurement heights can be increased.

(Third Modification)
The focus adjustment jig in the third modified example will be described with reference to Fig. 10. Fig. 10 is a side view showing the focus adjustment jig in the third modified example.

In the embodiment, the focus adjustment jig 200 is placed directly on the stage 103, and the lower end of the pattern surface 201a and the lower end of the mirror surface 202a are in contact with each other, and are also in contact with the upper surface of the stage 103. For this reason, the connection surface between the pattern surface 201a of the scale jig 201 and the mirror surface 202a of the mirror jig 202 has different amounts of light between the mirror surface and the actual scale, making it difficult to ensure continuity of the pattern.

In the third modified example, the focus adjustment jig 200 has spacers 203 of the same height installed under the scale jig 201 and the mirror jig 202, and the connection surface between the pattern surface 201a and the mirror surface 202a is moved upward away from the focal plane. The lower end of the pattern surface 201a and the lower end of the mirror surface 202a are away from the upper surface of the stage 103 and are not in contact. This ensures the continuity of the pattern near the focal plane and suppresses deterioration of measurement accuracy. In addition, it is possible to measure the focal position by placing only the mirror surface 202a of the mirror jig 202 within the field of view of the imaging device 101 and imaging only the mirror surface 202a, which has the same reflectance. Note that the lower end of the pattern surface 201a and the lower end of the mirror surface 202a may be separated.

(Fourth Modification)
The focus adjustment jig in the fourth modified example will be described with reference to Fig. 11. Fig. 11 is a side view showing the focus adjustment jig in the fourth modified example.

In the fourth modified example, the focus adjustment jig 200 has a rotation mechanism 204 below the scale jig 201 and the mirror jig 202, with the axis of rotation being a line that passes through the center of the connecting surface between the pattern surface 201a of the scale jig 201 and the mirror surface 202a of the mirror jig 202 and is perpendicular to the upper surface of the stage 103. The lower end of the pattern surface 201a and the lower end of the mirror surface 202a are not in contact with the upper surface of the stage 103. This allows the scale jig 201 and the mirror jig 202 to be rotated by the rotation mechanism 204, and the verticality of the optical system of the imaging device 101 and the lens 102 to be evaluated. If the shape of the front and rear waveforms of the brightness difference graph of the focal position changes when the scale jig 201 and the mirror jig 202 are rotated, it can be seen that the optical axis is not vertical.

(Fifth Modification)
The focal point adjustment jig in the fifth modified example will be described with reference to Fig. 12. Fig. 12 shows the focal point adjustment jig in the fifth modified example, Fig. 12(a) is a top view, and Fig. 12(b) is a side view.

The focus adjustment jig 200 in the fifth modified example is composed of a scale jig 201, a plurality of mirror jigs 202, and a spacer 203. The plurality of mirror jigs 202 include, for example, a first mirror jig 202_1, a second mirror jig 202_2, a third mirror jig 202_3, and a fourth mirror jig 202_4.
The scale jig 201 and multiple mirror jigs 202 are placed on the stage 103 so that the mirror surfaces 202a of the first mirror jig 202_1, the second mirror jig 202_2, the third mirror jig 202_3 and the fourth mirror jig 202_4 are positioned opposite the patterned surface 201a of the scale jig 201.

The scale jig 201 is wider in the width direction (Y-axis direction), but otherwise has the same configuration as the scale jig 201 in the embodiment. The first mirror jig 202_1, the second mirror jig 202_2, the third mirror jig 202_3, and the fourth mirror jig 202_4 have the same configuration as the mirror jig 202 in the embodiment.

The length in the X-axis direction of each of the first mirror jig 202_1, the second mirror jig 202_2, the third mirror jig 202_3, and the fourth mirror jig 202_4 is the same as the length of the scale jig 201. The length in the Y-axis direction (width) of the scale jig 201 is the same as the sum of the widths of the first mirror jig 202_1, the second mirror jig 202_2, the third mirror jig 202_3, and the fourth mirror jig 202_4.

The lower end of the mirror surface 202a of the first mirror jig 202_1 is in contact with the lower end of the pattern surface 201a of the scale jig 201. The lower end of the mirror surface 202a of the second mirror jig 202_2 is separated from the lower end of the pattern surface 201a of the scale jig 201 by the length in the X-axis direction of the first mirror jig 202_1. The lower end of the mirror surface 202a of the third mirror jig 202_3 is separated from the lower end of the pattern surface 201a of the scale jig 201 by the total length in the X-axis direction of the first mirror jig 202_1 and the second mirror jig 202_2. The lower end of the mirror surface 202a of the fourth mirror jig 202_4 is separated from the lower end of the pattern surface 201a of the scale jig 201 by the total length in the X-axis direction of the first mirror jig 202_1, the second mirror jig 202_2, and the third mirror jig 202_3.

The patterned surface 201a of the scale jig 201 is reflected by the mirror surface 202a of the first mirror jig 202_1, and the patterned surface 201a extends downward by an amount Ha. The patterned surface 201a is reflected by the mirror surface 202a of the second mirror jig 202_2, and the patterned surface 201a extends downward by an amount 2×Ha. The patterned surface 201a is reflected by the mirror surface 202a of the third mirror jig 202_3, and the patterned surface 201a extends downward by an amount 3×Ha. The patterned surface 201a is reflected by the mirror surface 202a of the fourth mirror jig 202_4, and the patterned surface 201a extends downward by an amount 4×Ha. This allows the pattern of the scale jig 201 reflected on the mirror surfaces 202a of the first mirror jig 202_1, the second mirror jig 202_2, and the third mirror jig 202_3 to be captured, thereby obtaining pattern images, i.e., brightness difference graphs, from a narrow range (Ha) farther away from the top surface of the stage 103 as viewed from the imaging device 101 to a wide range (4×Ha). This allows the size of the scale jig 201 to be made smaller, i.e., thinner (lower in height), enabling focusing over a wider range.

(Sixth Modification)
The focus adjustment jig in the sixth modified example will be described with reference to Fig. 13. Fig. 13 shows the focus adjustment jig in the sixth modified example, Fig. 13(a) is a top view, and Fig. 13(b) is a side view.

The focus adjustment jig in the fifth modified example has multiple mirror jigs 202, but the focus adjustment jig 200 in the sixth modified example has a movable mirror jig 202 instead of multiple mirror jigs 202.

The focus adjustment jig 200 is composed of a scale jig 201, a mirror jig 202, and a drive unit 205. The scale jig 201 has the same configuration as the scale jig 201 in the embodiment. The mirror jig 202 has the same configuration as the mirror jig 202 in the embodiment. The mirror jig 202 is moved by the drive unit 205 along the X-axis direction between a position where the bottom end of the mirror surface 202a is in contact with the bottom end of the pattern surface 201a of the scale jig 201 and a position a predetermined distance away. The scale jig 201 and the mirror jig 202 are placed on the stage 103 so that the mirror surface 202a of the mirror jig 202 is positioned opposite the pattern surface 201a of the scale jig 201. This allows capturing an image of the pattern of the scale jig 201 reflected on the mirror surface 202a of the mirror jig 202, and similarly to the fifth modified example, it is possible to obtain a pattern image, i.e., a shading graph, covering a narrow range to a wide range farther away from the top surface of the stage 103 as viewed from the imaging device 101.

(Seventh Modification)
The device in the seventh modified example will be described with reference to Fig. 14. Fig. 14 is a side view of the device in the seventh modified example.

In the embodiment, the imaging device 101 is fixedly disposed and cannot move in the Z-axis direction, but in the device of the seventh modified example, the imaging device 101 can be moved in the Z-axis direction by the drive unit 303. As a result, after the control unit 300 measures the amount of deviation, the drive unit 303 adjusts the installation position of the imaging device 101 to eliminate the deviation. By repeating this multiple times, the image is adjusted to the position where it is most in focus.

For example, the relationship between the focal position (center value) according to the number of stacked bonding stages (1st stage bond to nth stage bond, etc.) and the position of the imaging device 101 is obtained during adjustment. By setting the position of the imaging device 101 based on the number of stacked bonding stages during normal operation, it is possible to move the imaging device 101 to a position where the focus is achieved according to the number of stacked bonding stages.

The focus adjustment jig 200 is not limited to the focus adjustment jig in the embodiment, but the focus adjustment jig in the modified example can be used. The focus adjustment jig in the sixth modified example allows the measurement range of the focal position to be changed by the control unit 300, and by incorporating the focus adjustment jig in the sixth modified example into the device in the seventh modified example, it becomes possible to automate the focus adjustment.

(Eighth Modification)
The device in the eighth modified example will be described with reference to Fig. 15. Fig. 15 shows the device in the eighth modified example, with Fig. 15(a) being a top view and Fig. 15(b) being a side view.

The focus adjustment jig 200 in the eighth modified example is composed of a plurality of scale jigs 201 and a plurality of mirror jigs 202. The plurality of scale jigs 201 include, for example, a first scale jig 201_1 and a second scale jig 201_2. The plurality of mirror jigs 202 include, for example, a first mirror jig 202_1 and a second mirror jig 202_2. The first mirror jig 202_1 is installed opposite the first scale jig 201_1, the second mirror jig 202_2 is installed next to the first scale jig 201_1, and the second scale jig 201_2 is installed opposite the first scale jig 202_1 alternately on the stage 103.

In this state, when the patterns of the first scale jig 201_1 and the second scale jig 201_2 reflected by the first mirror jig 202_1 and the second mirror jig 202_2 are imaged, if there is no tilt in the optical system or the top surface of the stage 103, the measured values of the in-focus positions will be measured at the same position. However, if there is a tilt, a difference will appear in the measurement position depending on the tilt. The tilt in the X-axis direction of the stage 103 can be calculated based on the distance in the X-axis direction between the in-focus position measured on the first mirror jig 202_1 and the in-focus position measured on the second mirror jig 202_2.

Furthermore, multiple combinations of scale jigs 201 and mirror jigs 202 may be arranged alternately horizontally according to the width (length in the Y-axis direction) of the stage 103. If there is a difference in the focus measurement positions of the mirror jigs 202 arranged horizontally at intervals, it is confirmed that there is a tilt in the Y-axis direction of the stage 130, and the tilt can be calculated from the focal positions of the mirror jigs 202 arranged at intervals and the arrangement interval of the mirror jigs 202. Therefore, with the focus adjustment jig 200 in which multiple scale jigs 201 and mirror jigs 202 are arranged alternately, it is possible to measure the tilt of the stage 130 in both the X-axis and Y-axis directions.

Figure 16 is a top view showing an outline of the die bonder in the embodiment. Figure 17 is a diagram explaining the operation of the pickup head and bonding head when viewed from the direction of arrow A in Figure 16.

The die bonder 10 is broadly divided into a die supply unit 1 that supplies the die D to be mounted on the substrate S, a pickup unit 2, an intermediate stage unit 3, a bonding unit 4, a transport unit 5, a substrate supply unit 6, a substrate unloading unit 7, and a control unit 8 that monitors and controls the operation of each unit. The Y-axis direction is the front-to-back direction of the die bonder 10, and the X-axis direction is the left-to-right direction. The die supply unit 1 is located at the front side of the die bonder 10, and the bonding unit 4 is located at the back side. Here, one or more product areas (hereinafter referred to as package areas P) that will become one final package are printed on the substrate S.

First, the die supply unit 1 supplies the die D to be mounted in the package area P of the substrate S. The die supply unit 1 has a wafer holder 12 that holds the wafer 11, and a peeling unit 13, shown by a dotted line, that peels the die D from the wafer 11. The die supply unit 1 moves in the X and Y axis directions by a driving means (not shown), and moves the die D to be picked up to the position of the peeling unit 13. The peeling unit 13 corresponds to the stage 103 in the embodiment.

The pickup unit 2 has a pickup head 21 that picks up the die D, a pickup head Y drive unit 23 that moves the pickup head 21 in the Y-axis direction, a wafer recognition camera 24, and various drive units (not shown) that raise and lower, rotate, and move the collet 22 in the X-axis direction. The pickup head 21 has a collet 22 (see also FIG. 17) that suctions and holds the peeled die D at its tip, picks up the die D from the die supply unit 1, and places it on the intermediate stage 31. The pickup head 21 has various drive units (not shown) that raise and lower, rotate, and move the collet 22 in the X-axis direction. The wafer recognition camera 24 corresponds to the imaging device 101 in the embodiment, and is attached so as to be focused by the method shown in the embodiment or modified example. The imaged object is the die D attached to the dicing tape 16 placed on the peeling unit 13.

The intermediate stage section 3 has an intermediate stage 31 on which the die D is temporarily placed, and a stage recognition camera 32 for recognizing the die D on the intermediate stage 31. The intermediate stage 31 corresponds to the stage 103 in the embodiment. The stage recognition camera 32 corresponds to the imaging device 101 in the embodiment, and is attached so as to be focused by the method shown in the embodiment or the modified example.

The bonding unit 4 picks up a die D from the intermediate stage 31 and bonds it onto the package area P of the substrate S that is being transported onto the bonding stage BS, or bonds it by stacking it on top of a die that has already been bonded onto the package area P of the substrate S. The bonding unit 4 has a bonding head 41 equipped with a collet 42 (see also FIG. 17) that suction-holds the die D at its tip, similar to the pickup head 21, a Y drive unit 43 that moves the bonding head 41 in the Y-axis direction, and a substrate recognition camera 44 that captures an image of a position recognition mark (not shown) in the package area P of the substrate S and recognizes the bonding position. The bonding stage BS corresponds to the stage 103 in the embodiment. The substrate recognition camera 44 corresponds to the imaging device 101 in the embodiment, and is attached so as to be in focus by the method shown in the embodiment or modified example. With this configuration, the bonding head 41 corrects the pickup position and posture based on the imaging data of the stage recognition camera 32, picks up the die D from the intermediate stage 31, and bonds the die D to the substrate based on the imaging data of the substrate recognition camera 44.

The transport unit 5 has a substrate transport claw 51 that grips and transports the substrate S, and a transport lane 52 along which the substrate S moves. The substrate S moves by driving a nut (not shown) of the substrate transport claw 51 provided on the transport lane 52 with a ball screw (not shown) provided along the transport lane 52. With this configuration, the substrate S moves from the substrate supply unit 6 along the transport lane 52 to the bonding position, and after bonding, moves to the substrate discharge unit 7 and hands the substrate S over to the substrate discharge unit 7.

Next, the configuration of the die supply unit 1 will be described with reference to Figure 18. Figure 18 is a schematic cross-sectional view showing the main parts of the die supply unit in Figure 16.

The die supply unit 1 includes a wafer holder 12 that moves horizontally (XY axis directions) and a peeling unit 13 that moves vertically. The wafer holder 12 has an expand ring 15 that holds a wafer ring 14, and a support ring 17 that horizontally positions a dicing tape 16 held by the wafer ring 14 and having multiple dies D attached thereto. The peeling unit 13 is disposed inside the support ring 17.

When the die D is pushed up, the die supply unit 1 lowers the expand ring 15 holding the wafer ring 14. As a result, the dicing tape 16 held by the wafer ring 14 is stretched, widening the gap between the dies D, and the peeling unit 13 peels the dies D from the dicing tape 16, improving the pick-up of the dies D. The adhesive that bonds the dies to the substrate changes from liquid to film, and a film-like adhesive material called a die attachment film (DAF) 18 is attached between the wafer 11 and the dicing tape 16. In the case of a wafer 11 having a die attachment film 18, dicing is performed on the wafer 11 and the die attachment film 18. Therefore, in the peeling process, the wafer 11 and the die attachment film 18 are peeled off from the dicing tape 16.

The control system of the die bonder 10 will be described with reference to FIG. 19. FIG. 19 is a block diagram showing the schematic configuration of the control system of the die bonder shown in FIG. 16.

19, the control system 80 includes a control unit 8, a drive unit 86, a signal unit 87, and an optical system 88. The control unit 8 is broadly divided into a control/arithmetic unit 81 mainly composed of a CPU (Central Processor Unit), a storage unit 82, an input/output unit 83, a bus line 84, and a power supply unit 85. The storage unit 82 includes a main storage unit 82a composed of a RAM that stores processing programs, etc., and an auxiliary storage unit 82b composed of a HDD that stores control data and image data required for control. The input/output unit 83 includes a monitor 83a that displays the device status and information, a touch panel 83b that inputs operator instructions, a mouse 83c that operates the monitor, and an image capture unit 83d that captures image data from the optical system 88. The input/output device 83 also includes a motor control device 83e that controls the drive units 86, such as the XY table (not shown) of the die supply unit 1 and the ZY drive shaft of the bonding head table, and an I/O signal control device 83f that takes in or controls signals from a signal unit 87, such as various sensor signals and switches for lighting devices. The optical system 88 includes the wafer recognition camera 24, stage recognition camera 32, and substrate recognition camera 44 shown in FIG. 16. The control/arithmetic device 81 takes in the necessary data via the bus line 84, performs calculations, and controls the bonding head 41, etc., and sends information to the monitor 83a, etc.

The control unit 8 stores image data captured by the optical system 88 in the storage device 82 via the image capture device 83d. Using software programmed based on the stored image data, the control/arithmetic unit 81 is used to position the die D and substrate S, inspect the application pattern of the paste adhesive, and inspect the surfaces of the die D and substrate S. Based on the positions of the die D and substrate S calculated by the control/arithmetic unit 81, the software drives the drive unit 86 via the motor control device 83e. This process determines the position of the die D on the wafer 11, and the die supply unit 1 and the die bonding unit 4 are operated to bond the die D onto the substrate S. The recognition camera used in the optical system 88 is a grayscale or color camera, etc., and converts light intensity into a numerical value.

Next, a method for manufacturing a semiconductor device using the die bonder in the embodiment will be described with reference to FIG. 20. FIG. 20 is a flow chart showing a method for manufacturing a semiconductor device using the die bonder shown in FIG. 16.

(Wafer/substrate loading process: step S51)
The wafer ring 14 holding the dicing tape 16 to which the die D separated from the wafer 11 is affixed is stored in a wafer cassette (not shown) and is carried into the die bonder 10. The control unit 8 supplies the wafer ring 14 from the wafer cassette filled with the wafer ring 14 to the die supply unit 1. In addition, the control unit 8 prepares a substrate S and carries it into the die bonder 10. The control unit 8 attaches the substrate S to the substrate transport claws 51 in the substrate supply unit 6.

(Pickup process: step S52)
The control unit 8 moves the wafer ring 14 so that the desired die D can be picked up from the wafer ring 14 by the wafer holder 12, and performs positioning and surface inspection based on data captured by the wafer recognition camera 24. The control unit 8 peels the positioned die D from the dicing tape 16 by the peeling unit 13.

The control unit 8 picks up the peeled die D from the wafer 11 using the pick-up head 21. In this way, the die D peeled off from the dicing tape 16 is attracted to and held by the collet 22 of the pick-up head 21 and transported to the next process (step S53). Then, when the collet 22 that transported the die D to the next process returns to the die supply unit 1, the next die D is peeled off from the dicing tape 16 according to the above-mentioned procedure, and thereafter, the dies D are peeled off one by one from the dicing tape 16 according to the same procedure.

(Bonding process: step S53)
The control unit 8 places the die D picked up from the wafer 11 by the pick-up head 21 on the intermediate stage 31, and then picks up the die D again from the intermediate stage 31 with the bonding head 41 and bonds it to the positioned substrate S. The control unit 8 performs an inspection based on image data captured by the substrate recognition camera 44 to see if the die D has been bonded at the desired position, etc.

(Substrate removal process: step S54)
The control unit 8 causes the substrate unloading unit 7 to take out the substrate S having the bonded die D from the substrate transport claws 51. The substrate S is then unloaded from the die bonder 10.

As described above, the die D is mounted on the substrate S via the die attachment film 18 and is carried out from the die bonder. Thereafter, in the wire bonding process, the die D is electrically connected to the electrode of the substrate S via the Au wire. Next, the substrate S on which the die D is mounted is carried into the die bonder, and the second die D is stacked on the die D mounted on the substrate S via the die attachment film 18, and after being carried out from the die bonder, is electrically connected to the electrode of the substrate S via the Au wire in the wire bonding process. The second die D is peeled off from the dicing tape 16 by the above-mentioned method, and then transported to the pelleting process and stacked on the die D. After the above process is repeated a predetermined number of times, the substrate S is transported to the molding process, and the multiple dies D and the Au wires are sealed with molding resin (not shown) to complete the stacked package.

The invention made by the present inventors has been specifically described above based on the embodiments, modifications, and examples, but it goes without saying that the present disclosure is not limited to the above embodiments, modifications, and examples, and various modifications are possible.

For example, in the embodiment, an example was described in which a film-like adhesive material called a die attach film (DAF) was used to attach between the wafer 11 and the dicing tape 16, but a paste-like adhesive may also be applied to the substrate in the preform section. In this case, the focus of the recognition camera provided in the preform section to check the position where the paste is applied and the application status is adjusted using the focus adjustment jig in the embodiment.

In the embodiment, an intermediate stage section 3 is provided between the die supply section 1 and the bonding section 4, the die D picked up from the die supply section 1 by the pick-up head 21 is placed on the intermediate stage 31, and the die D is picked up again from the intermediate stage 31 by the bonding head 41 and bonded to the transported substrate S. However, the die D picked up from the die supply section 1 by the bonding head 41 may be bonded to the substrate S.

101: Imaging device 103: Stage 201: Scale jig (first jig)
201a: Pattern surface 202: Mirror jig (second jig)
202a...Mirror surface 200...Focus adjustment jig

Claims (22)

1. A focus adjustment method for adjusting a distance between an image capture target placed on a stage and an image capture device located above the image capture target so that the image capture target is positioned at a focus of the image capture device, comprising:
A focus adjustment method in which a first jig having a patterned surface and a second jig having a mirror surface are placed on the stage, a brightness difference graph is created from two pattern images: a pattern image obtained from the patterned surface and a pattern image obtained from a virtual image of the patterned surface reflected on the mirror surface, and an optimal focus position is calculated from the brightness difference graph. A focus adjustment tool for use in the focus adjustment method of claim 1 ,
The first jig is set to have a first predetermined angle with respect to an upper surface of the stage,
The second jig is set to have an angle of 90 degrees with respect to the pattern surface and a second predetermined angle with respect to the upper surface of the stage ,
A focus adjustment fixture configured so that the mirror surface is imaged by the imaging device. 3. The focus adjustment jig according to claim 2 ,
A focus adjustment tool, wherein the first predetermined angle is 45 degrees and the second predetermined angle is 45 degrees. 3. The focus adjustment jig according to claim 2 ,
The focus adjustment tool, wherein the first predetermined angle is less than 45 degrees and the second predetermined angle is greater than 45 degrees. 3. The focus adjustment jig according to claim 2 ,
The focus adjustment tool, wherein the first predetermined angle is greater than 45 degrees and the second predetermined angle is less than 45 degrees. 3. The focus adjustment jig according to claim 2 ,
A focus adjustment jig in which the lower end of the patterned surface and the lower end of the mirror surface are in contact with each other. 3. The focus adjustment jig according to claim 2 ,
A focus adjustment jig in which the bottom end of the patterned surface and the bottom end of the mirror surface are spaced apart. 3. The focus adjustment jig according to claim 2 ,
A focus adjustment jig in which the lower end of the patterned surface and the lower end of the mirror surface are in contact with the upper surface of the stage. 3. The focus adjustment jig according to claim 2 ,
A focus adjustment jig in which the lower end of the patterned surface and the lower end of the mirror surface are spaced apart from the upper surface of the stage. 3. The focus adjustment jig according to claim 2 ,
A focus adjustment jig in which the patterned surface and the mirror surface are rotatable about an axis perpendicular to the top surface of the stage. The focus adjustment jig according to claim 2 ,
A plurality of the second jigs are provided,
A focus adjustment jig in which the distances between the bottom ends of the mirror surfaces of the plurality of second jigs and the bottom ends of the patterned surface are different from one another. 3. The focus adjustment jig according to claim 2 ,
A plurality of sets of the first jig and the second jig are arranged along a first direction,
A focus adjustment jig in which the first jigs and the second jigs are alternately arranged along a second direction different from the first direction. 3. The focus adjustment jig according to claim 2 ,
A focus adjustment jig in which the distance between the bottom end of the mirror surface and the bottom end of the pattern surface is variable by a drive unit that moves the mirror surface. A die bonding apparatus that adjusts the focal position of an imaging device using the focus adjustment jig of claim 2 ,
the stage on which the imaging object is placed during normal operation and on which the focus adjustment jig is placed during adjustment;
The imaging device is disposed above the stage; and
a control unit configured to capture an image of the focus adjustment jig with the imaging device during adjustment to measure a focal position of the imaging device;
A die bonding apparatus comprising: 15. The die bonding apparatus of claim 14 ,
The control unit of the die bonding apparatus is configured to determine the contrast of an edge portion of a pattern from a captured image and calculate how far the edge portion is shifted from a desired focus position. 16. The die bonding apparatus of claim 15 ,
The control unit of the die bonding apparatus is configured to calculate the relationship between brightness and position based on the pixel values of the captured image, calculate the focal position at which the brightness difference is maximum based on the brightness and position, and calculate the desired position to focus the imaging device based on the calculated focal position. 16. The die bonding apparatus of claim 15 ,
The control unit of the die bonding apparatus is configured to calculate the relationship between brightness and position based on the pixel values of the captured image, calculate a focal position using statistical approximation calculation from the brightness and darkness differences at the position where the brightness and darkness difference is maximum and at positions before and after that position based on the brightness and darkness value and the position, and calculate the desired position to focus the imaging device based on the calculated focal position. 15. The die bonding apparatus of claim 14 ,
The control unit is configured to adjust a height of the imaging device based on the measured focal position. 15. The die bonding apparatus of claim 14 ,
The object to be imaged is a die bonding apparatus in which a paste-like adhesive is applied to a substrate. 20. The die bonding apparatus of claim 19 ,
The control unit is configured to perform an appearance inspection of the paste adhesive by the imaging device. 15. The die bonding apparatus of claim 14 ,
A die bonding apparatus in which the imaging object is a die bonded onto a substrate or an already bonded die. A step of carrying a substrate into the die bonding apparatus of claim 14 ;
picking up the die;
Bonding the picked up die onto the substrate or onto an already bonded die;
A method for manufacturing a semiconductor device comprising the steps of:

Images