JP7373436B2 - Die bonding equipment and semiconductor device manufacturing method - Google Patents

Description

The present disclosure relates to a die bonding apparatus, and is applicable to, for example, a die bonder that images an attachment area with a plurality of recognition cameras.

Part of the manufacturing process for semiconductor devices is the process of assembling a package by mounting a semiconductor chip (hereinafter simply referred to as a die) on a wiring board, lead frame, etc. (hereinafter simply referred to as a board). The process includes a process (dicing process) of dividing die from a semiconductor wafer (hereinafter simply referred to as wafer) and a bonding process of placing the divided die on a substrate. A semiconductor manufacturing device used in the bonding process is a die bonding device such as a die bonder.

A die bonder is a device that uses resin paste, solder, gold plating, or the like as a bonding material to bond (place and bond) a die onto a substrate or an already bonded die. For example, in a die bonder that bonds a die to the surface of a substrate, a suction nozzle called a collet attached to the tip of the bonding head is used to pick up the die from the wafer and place it on a predetermined position on the substrate. The operation (work) of applying a pressing force and performing bonding by heating the bonding material is repeatedly performed.

When resin is used as the bonding material, resin pastes such as Ag epoxy and acrylic are used as adhesives (hereinafter referred to as paste adhesives). A paste adhesive for bonding the die to the substrate is enclosed in a syringe, and the syringe moves up and down relative to the substrate to inject and apply the paste adhesive. That is, a predetermined amount of the paste adhesive is applied to a predetermined position using a syringe filled with the paste adhesive, and the die is bonded by pressing and baking onto the paste adhesive. A recognition camera is installed near the syringe, and this recognition camera confirms and determines the position where the paste adhesive will be applied, and also ensures that the applied paste adhesive is in the specified position and shape. It is confirmed whether a predetermined amount has been applied.

In addition, a recognition camera is installed near the bonding head, and this recognition camera confirms and determines the position of the substrate to which the die is bonded, and also checks whether the bonded die is bonded in the specified position. It is confirmed.

Japanese Patent Application Publication No. 2013-197277

When a plurality of objects are imaged with a single imaging device using a non-telecentric lens, objects that are far away from directly below the imaging device are imaged from an oblique angle, resulting in viewing the sides of the three-dimensional shape.
An object of the present disclosure is to provide a technique that can improve the uniformity of imaging conditions for a plurality of imaging targets.
Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

A brief overview of typical features of the present disclosure is as follows.
That is, the die bonding apparatus includes a transport path for transporting a substrate, a plurality of imaging devices fixedly disposed in a line above the transport path along the width direction of the substrate, and a plurality of imaging devices located above the substrate. A plurality of attachment regions in a row along the width direction are captured by the plurality of imaging devices to obtain a plurality of images, a composite image is generated based on the plurality of acquired images, and a composite image is generated based on the composite image. A control unit configured to recognize an imaging target in the attachment area. The imaging fields of each imaging device overlap on the substrate, and the overlapping imaging fields are configured to be larger than the attachment area.

According to the die bonding apparatus described above, it is possible to improve the uniformity of imaging conditions for a plurality of imaging targets.

FIG. 1(a) is a perspective view showing a normal field of view optical system, and FIG. 1(b) is a perspective view of a wide field of view optical system. FIG. 2(a) is a conceptual diagram of a wide-field optical system using a macro lens, and FIG. 2(b) is a conceptual diagram of a wide-field optical system using a telecentric lens. FIG. 3(a) is a diagram showing an image of the three-dimensional shape of the paste, and FIG. 3(b) is a diagram showing bright lines on the paste when the substrate is viewed in a wide area with a macro lens. FIG. 4(a) is a top view illustrating multiple imaging devices according to the embodiment, and FIG. 4(b) is a side view when viewed from the direction of arrow A in FIG. 4(a). FIG. 5 is a diagram illustrating a lighting device used in the imaging device of the embodiment. FIG. 6 is a top view illustrating the overlapping of imaging fields of view of a plurality of imaging devices. FIG. 7 is a side view when viewed from the direction of arrow A in FIG. FIG. 8 is a diagram illustrating the amount of overlap of imaging fields of view. FIG. 9 is a diagram explaining image mosaicing and coordinate mapping. FIG. 10 is a schematic diagram illustrating image mosaicing and coordinate transformation using a calibration plate. FIG. 11 is a diagram illustrating distortion. FIG. 12 is a diagram showing equations of transformation matrices for affine transformation and projective transformation. FIG. 13 is a diagram illustrating image mosaicking and coordinate transformation using a target model of a substrate. FIG. 14 is a diagram illustrating the influence of temporal displacement of the imaging device. FIG. 15 is a diagram illustrating spatial re-correction. FIG. 16 is a diagram illustrating a method of changing the height of the calibration plate. FIG. 17 is a diagram illustrating markers provided on the chute. FIG. 18 is a perspective view illustrating multiple imaging devices in a modified example. FIG. 19 is a top view schematically showing the die bonder in the example. FIG. 20 is a diagram illustrating the operation of the pickup head and the bonding head when viewed from the direction of arrow A in FIG. 19. FIG. 21 is a schematic cross-sectional view showing the main parts of the die supply section of FIG. 19. FIG. 22 is a block diagram showing a schematic configuration of the control system of the die bonder shown in FIG. 19. FIG. 23 is a flowchart showing a method for manufacturing a semiconductor device.

Embodiments, modifications, and examples will be described below with reference to the drawings. However, in the following description, the same constituent elements may be denoted by the same reference numerals and repeated explanations may be omitted. In addition, in order to make the explanation more clear, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual aspect, but these are only examples, and the interpretation of the present invention is It is not limited.

First, the technology studied by the present inventors will be explained using FIGS. 1 to 3. FIG. 1(a) is a perspective view showing a normal field of view optical system, and FIG. 1(b) is a perspective view of a wide field of view optical system.

In the operation of sequentially positioning the substrate S, attaching it (die bonding or paste coating), and inspecting it, as shown in FIG. Since only an area slightly larger than the attachment area AA is imaged, as many images and image recognitions as there are attachment areas AA are required. Here, as an example, the substrate S has six attachment areas AA in one row, and an example is shown in which five rows of attachment areas are provided. A low-resolution imaging device is an imaging device that can only image an area slightly larger than one attachment area with sufficient resolution, and is, for example, an imaging device with a resolution of about 300,000 to about 1.3 million pixels.

Therefore, as shown in FIG. 1(a), the imaging device CML is moved in the width direction (Y-axis direction) of the substrate S to perform imaging and image recognition of other attachment areas in that row. It is necessary to repeat the process of performing processing based on . Note that after imaging one row, the substrate S is moved in the substrate transport direction (X-axis direction) and imaging of the next row is performed.

Therefore, a moving mechanism for moving the support member (not shown) of the imaging device CML in the width direction of the substrate S is required, which makes the supporting mechanism of the imaging device CML complicated, large, and expensive. In addition, because of the time required to move the imaging device CML in the width direction, and the waiting time for imaging until the shaking of the imaging device CML due to vibrations caused by the movement of the support member subsides, the speed of the die bonder must be increased. I can't. Alternatively, a vibration prevention mechanism is required to prevent vibration, and furthermore, the die bonder becomes expensive. Furthermore, if there is a mechanism that moves back and forth above the attachment area and below the imaging device, it is necessary to take an image at a time when the imaging field of view is not blocked by the mechanism. By securing this imaging timing, the speed of the die bonder cannot be increased.

On the other hand, instead of repeating this process for each attachment after the substrate is transported, if a wide-field optical system using a high-resolution imaging device CMH is used, as shown in Figure 1(b), it is possible to position the front stage or the rear stage. Performing the inspection by imaging and recognizing the entire attachment area of the substrate S (all tabs together) or at least one row of attachment areas in the width direction of the substrate improves processing time and solves the above-mentioned problems. Here, a high-resolution imaging device is an imaging device that can image at least the entire area of one row in the width direction of the substrate S at a time with sufficient resolution, for example, a device with a resolution of about 5 million pixels or more. It is an imaging device. A row includes a plurality of attachment areas, for example at least four attachment areas.

However, wide-field optical systems (wide-area cameras) have the following problems. This problem will be explained using FIGS. 2 and 3. FIG. 2(a) is a conceptual diagram of a wide-field optical system using a macro lens, and FIG. 2(b) is a conceptual diagram of a wide-field optical system using a telecentric lens. FIG. 3(a) is a diagram showing an image of the three-dimensional shape of the paste, and FIG. 3(b) is a diagram showing bright lines on the paste when the substrate is viewed in a wide area with a macro lens.

(1) Ensuring telecentricity Simply lowering the magnification of the macro lens will make the area wider, but the further you move away from the center of the field of view, the more you will see it from diagonally above, as shown in Figure 2(a). Although the side surface of the object to be imaged OBC is not visible, the right side surface is visible for the object to be imaged on the left side OBL, and the left side surface is visible for the object to be imaged on the right side OBR, so that the side surface of the three-dimensional shape is visible. Further, the magnification changes depending on the height of the object to be imaged OBL, and if the height changes, alignment becomes difficult, for example. For example, the height of a paste applied to a substrate or a die stacked on a substrate differs depending on the location.

These problems can be solved by using a telecentric lens. Since the telecentric lens focuses parallel light, the sides of all objects to be imaged become invisible. However, in that case, as shown in Figure 2(b), a lens with a larger aperture than the desired field of view is generally required. This requires a larger aperture, and the focal length also becomes longer. Mounting such a large lens in a die bonding device is not preferable from the viewpoint of efficiency.

(2) Irradiation of uniform illumination within the field of view When trying to secure a wide area using a non-telecentric lens, the end of the field of view will be viewed from diagonally above. Since the directions are reversed at the right and left ends, or at the top and bottom ends of the field of view, the direction of illumination tends to be uneven. Furthermore, even when parallel light using telecentric light is irradiated, it is difficult to obtain an image uniformly irradiated within the imaging field of view. For example, as shown in FIG. 3(a), the paste adhesive PA applied to the substrate in the shape of a cross is formed such that the center portion is high and the tip portion is low. When a substrate coated with a paste adhesive as shown in Figure 3(a) is viewed in a wide area with a macro lens, the central part of the imaging field of view is directly centered on the object to be imaged, as shown in Figure 3(b). It is bright when viewed from above, but the peripheral area is dark when viewed diagonally, and since the height of the paste adhesive is not uniform, the bright line above the paste adhesive PA shifts. Here, the center of the field of view of the imaging device is located at the center of the image in FIG. 3(b). The substrate S has tabs TB, which are six attachment areas in one row, and seven rows are shown. A paste adhesive PA is applied to four rows of tabs TB on the right side of the substrate S.

Next, an embodiment that solves the above-mentioned problems will be described with reference to FIGS. 4 and 5. FIG. 4(a) is a top view illustrating multiple imaging devices according to the embodiment, and FIG. 4(b) is a side view when viewed from the direction of arrow A in FIG. 4(a). FIGS. 5A and 5B are diagrams illustrating an illumination device used in the imaging device of the embodiment, in which FIG. 5A is a cross-sectional view and FIG. 5B is a side view of the illumination device.

As an embodiment for solving the above-mentioned problems, multiple imaging devices (stereo conversion) are performed. For example, as shown in FIG. 4, a plurality of imaging devices CM1 to CM4 are fixedly arranged above the substrate S in a line in the width direction of the substrate S (Y-axis direction). Here, each of the imaging devices CM1 to CM4 is an imaging device with a resolution equal to or higher than that of the imaging device CML, and cannot image the entire area of one row in the width direction of the substrate S at once with sufficient resolution. It is an imaging device. Furthermore, although each of the imaging devices CM1 to CM4 may use a telecentric lens, it is preferable to use a non-telecentric lens such as a macro lens. These imaging devices CM1 to CM4 are at the same height and spaced apart from each other by a predetermined distance in the horizontal direction, and the optical axes of the imaging devices CM1 to CM4 are parallel to each other and perpendicular to the substrate S. Note that the optical axes of the imaging devices CM1 to CM4 may be slightly inclined from the perpendicular line to the substrate S within a range that allows defocusing in the imaging field of view.

In this embodiment, each of the imaging devices CM1 to CM4 images the object to be imaged in the attachment areas AA11 to AA14. Furthermore, the imaging fields of view IA1 to IA4 of the imaging devices CM1 to CM4 do not overlap. Furthermore, by moving the substrate S in the transport direction (Y-axis direction), images of the remaining rows of objects to be imaged are sequentially imaged. By using multiple imaging devices, images can be taken almost directly above the object to be imaged, and the uniformity of illumination within the imaging field of view can be improved for inspection. Furthermore, by connecting multiple imaging devices, there is no need to move the imaging devices, and it is possible to obtain the same processing efficiency as a wide-field optical system.

Here, as shown in FIGS. 4(a) and 4(b), the substrate S is rectangular and flat, and has a large number of attachment areas AA11 to AA14, AA21 to AA24, etc. in the vertical and horizontal directions. ing. The length of the substrate S in the transport direction (X-axis direction) is longer than the length in the width direction (Y-axis direction).

Preferably, each of the multiple imaging devices has a similar illumination system. For example, as shown in FIG. 5(a), between the imaging devices CM1 to CM4 and the substrate S, there is a lighting device LD that includes a surface emitting illumination (light source) SL and a half mirror (semi-transmissive mirror) HM. is located. The irradiation light from the surface emitting illumination SL is reflected by the half mirror HM along the same optical axis as the imaging devices CM1 to CM4, and is irradiated onto the imaging target in the attachment areas AA11 to AA14 of the substrate S. The scattered light irradiated onto the imaging targets in the attachment areas AA11 to AA14 with the same optical axis as the imaging devices CM1 to CM4 is reflected by the imaging targets in the attachment areas AA11 to AA14, and the specularly reflected light is reflected by the half mirror HM. The light passes through and reaches the imaging devices CM1 to CM4, and forms an image of the object to be imaged in the attachment areas AA11 to AA14. That is, the illumination device LD has a function of coaxial epi-illumination (coaxial illumination).

As shown in FIG. 5(b), the length of the surface emitting illumination SL and the half mirror HM in the Y-axis direction is configured to be slightly wider than the entire imaging field of view of the imaging devices CM1 to CM4 in the width direction of the substrate S. The surface emitting illumination SL is divided into light emitting areas SL1 to SL4 that are slightly wider than the respective imaging fields of the imaging devices CM1 to CM4, and can be turned on and off individually. Since the light emitting area of the coaxial illumination device is divided, it is possible to control the light for each of the imaging devices CM1 to CM4. This makes it possible to improve the uniformity of illumination in all areas of the imaging field of view of the imaging devices CM1 to CM4. Note that, as described later, when the imaging fields of view of the imaging devices CM1 to CM4 overlap, the light emitting areas SL1 to SL4 also overlap.

Next, the overlap of the imaging fields of the plurality of imaging devices will be explained using FIGS. 6 to 8. FIG. 6 is a top view illustrating the overlapping of imaging fields of view of a plurality of imaging devices. FIG. 7 is a side view when viewed from the direction of arrow A in FIG. FIG. 8 is a diagram illustrating the amount of overlap of imaging fields of view.

In the embodiment described above, the respective imaging fields of view IA1 to IA4 of the imaging devices CM1 to CM4 do not overlap. However, when multiple imaging devices are installed, the various product pitches (pitch of attachment areas) and the pitch of the imaging devices are not necessarily the same, so as shown in Figures 6 and 7, the imaging fields overlap to some extent. It is preferable to let

6 and 7 show an example in which four imaging devices are provided and six attachment regions are provided in one row of the substrate S, and the pitch of the imaging devices is larger than the pitch of the attachment regions. For this reason, the imaging fields of adjacent imaging devices are made to overlap, so that, for example, the imaging field of one imaging device includes two or more imaging objects. Therefore, each of the imaging devices CM1 to CM4 has a higher resolution than the imaging device CML. Each of the imaging devices CM1 to CM4 is an imaging device that cannot image the entire area of one row of the substrate S in the width direction at once with sufficient resolution; An imaging device that can capture an image with sufficient resolution may also be used. Here, as shown in FIG. 6, for example, the substrate S is rectangular and flat, and has a large number of attachment areas AA11 to AA16, AA21 to AA26, etc. in the vertical and horizontal directions. The length of the substrate S in the transport direction (X-axis direction) is longer than the length in the width direction (Y-axis direction).

The overlapping region OVL of the imaging field of view may have a size that includes the maximum size of the imaging target (the maximum product size may be maintained). As a result, all of the objects to be imaged are completely contained in one of the imaging fields of view. As shown in FIG. 8, the overlapping area OVL only needs to be large enough to fit the imaging target object OB2. For example, if the overlapping area is the maximum tab size for a substrate substrate, all tabs can be placed in one field of view. Contains a full view of the tab.

Combining a plurality of captured images will be explained using FIGS. 9 to 15. FIG. 9 is a diagram explaining image mosaicing and coordinate mapping. FIG. 10 is a schematic diagram illustrating image mosaicing and coordinate transformation using a calibration plate. FIG. 11 is a diagram illustrating distortion. FIG. 12 is a diagram showing equations of transformation matrices for affine transformation and projective transformation. FIG. 13 is a diagram illustrating image mosaicking and coordinate transformation using a target model of a substrate. FIG. 14 is an image taken with multiple imaging devices of a state in which paste adhesive is applied on the tabs of a multi-lead frame, and FIG. 14(a) is an image taken when there is no change over time. (b) is a captured image when there is variation over time. FIG. 15 is a diagram illustrating spatial re-correction. FIG. 15(a) is a diagram showing a state before spatial re-correction, and FIG. 15(b) is a diagram showing a state after spatial re-correction.

In order to suppress the amount of overlap, the control unit CNT combines images captured by a plurality of imaging devices by image mosaicing or the like. Typical image mosaicing attempts to seamlessly stitch multiple images together, which may result in loss of image calibration.

Therefore, in the embodiment, in combining images captured by multiple imaging devices,
(A) When shipping or adjusting the die bonding equipment, image mosaicing and coordinate transformation are performed using a calibration plate.
(B) During fine adjustment of the die bonding apparatus or during continuous operation, image mosaicing is performed using the target model of the substrate and coordinate conversion is performed using the target model placed on the chute.

The above (A) will be explained using FIGS. 9 to 12.
As shown in FIG. 9, the control unit CNT displays the coordinate marker CMRK, which is a scale that covers all the imaging field of view of the multiple imaging devices, when adjusting the die bonding apparatus, and displays the coordinate marker CMRK that is a scale that covers all the imaging fields of the multiple imaging devices, and selects a coordinate marker that falls within the overlapping region OVL range. Coordinate transformation is performed on the image by projective transformation, affine transformation, etc. using the same intersection point IP of CMRK as a reference, and a single image (composite image) is obtained by smoothly joining the images of each imaging device. Here, the coordinate marker CMRK is used by preparing a calibration plate as an adjustment jig and marking the plate, and the coordinate marker CMRK is, for example, grid-shaped. During coordinate transformation, a marker is required to guarantee the positional relationship of the entire space. If there is a coordinate marker CMRK that covers the entire synthetic field of view as shown in Figure 9, the positional relationship of the entire space can be guaranteed during coordinate transformation such as projective transformation, and the image space coordinates and real space can be adjusted at each intersection pitch. Coordinate matching is possible.

As shown in FIG. 10, the control unit CNT images one large calibration plate CP having a lattice pattern using, for example, three imaging devices with different fields of view. The three imaging devices have overlapping regions OV12 and OV23 in which the fields of view overlap to some extent due to the adjacent imaging devices. Intersection points IP of the checkered patterns in the overlapping regions OV12 and OV23 are indicated by black dots.

First, the control unit CNT transforms the pixel coordinates of an image of an adjacent imaging device based on one of the adjacent imaging devices using affine transformation or projective transformation. Here, as an example, the reference image will be described as image IV1, and the converted image as image IV2. In the transformation, each parameter of the transformation matrix of affine transformation or projective transformation is calculated so that the coordinates (black point coordinates) of the intersection point IP in the images to be transformed match the coordinates (black point coordinates) of the intersection point IP in the corresponding reference image. Here, in general, a transformation matrix for affine transformation is shown in equation (1) in FIG. 12, and a determinant for projective transformation is shown in equation (2) in FIG. 12. Generally, it is sufficient to have the coordinates of three points to calculate the transformation matrix. It is preferable to perform the conversion.

If the reference image IV1 has a distortion represented by a barrel shape or a pincushion shape as shown in Fig. 11, first correct the original image using the intersection points IP of all the calibration plates CP that fall within the field of view. It is preferable to perform distortion correction by converting the image into an image conforming to the vertical orthogonal coordinate system (first distortion correction). Thereby, areas other than the overlapping areas OV12 and OV23 can be incorporated into the composite image by simply adjusting the magnification.

Since coordinate alignment is performed in the pixel coordinate system, the coordinates of image IV2 after transformation are required to be integer values, but pixels transformed by affine transformation or projective transformation do not always fit in the same location. , the coordinates may become intermediate values after conversion. In such a case, each coordinate of the transformed image is subjected to gray value interpolation using the nearest neighbor method, bilinear method, bicubic method, etc. from the gray value of the adjacent transformed coordinate.

The above (B) will be explained using FIGS. 13 to 15.
In the conversion during adjustment work before production starts, the alignment of the image space and the actual coordinate space is relatively easy because a large number of intersection points IP of the calibration plate CP, which indicate the reference coordinates, are arranged at equal pitches in the image space within the field of view. It's easy. On the other hand, during continuous operation or simple adjustment, image synthesis and coordinate alignment are performed without using the calibration plate CP. For image synthesis, it is only necessary to know the positions that indicate the same location, so a positioning target mark TM on the substrate is used. The positioning target mark TM is used because a template model has been registered as a tab positioning process during attachment (bonding or pasting). As shown in FIG. 13, when a plurality of tabs are included in the overlapping areas OV12 and OV23 of the images, three or more points are secured using positioning target marks TM of adjacent tabs. If only one tab can fit into the overlapping area, three positioning target marks TM are registered in advance in one tab as a template image model.

With this method, it is possible to synthesize images by aligning their coordinates, but alignment with real space is not possible. Even if one of the images is used as a reference, if the images are combined as they are without first performing alignment with the coordinate space, as shown in FIG. 11, images IV2 and IV2 adjacent to image IV1 as the reference image Image IV3 adjacent to image IV3 is affected by the distortion of image IV1. The deviation due to distortion is amplified the most in the image IV3 at the farthest position when the images are successively adjacent to each other starting from the image IV1. In order to suppress this amplification amount, a marker SMRK is installed at a known coordinate on the chute SCT, and the coordinates of the installed marker SMRK are measured again from the image, thereby returning the combined image at once. Since the distortion of the image here depends on the lens of the imaging device, image synthesis is performed after the first transformation (first distortion correction) is performed, and marker SMRK on the shoot SCT is used to align the overall coordinates. is preferable. That is, the control unit CNT corrects the real space and the image space using the coordinate marker CMRK, and then grasps the coordinates of the marker SMRK separately provided on the chute SCT as a conveyance path. Here, the chute SCT is located outside both ends of the substrate S in the width direction.

As described above, the coordinate markers CMRK are adjusted as adjustment work before the die bonding device starts production. However, as construction progresses, the field of view of each imaging device slightly changes over time due to the self-heating of the imaging device, its saturation state, and variations in heat distribution between imaging devices, as shown in Figure 14(b). It may have some displacement. Here, the image within the imaging field of view IA2 of the imaging device CM2 is shifted to the right with respect to the image within the imaging field of view IA1 of the imaging device CM1. That is, the imaging device CM2 is displaced to the right. Also, the area surrounded by a rectangular frame indicates the vicinity of the lower left corner of each tab. This deviation cannot be ignored in a die bonding apparatus that requires precision on the micrometer level. Even during construction, it is necessary to correct these minute deviations. A method for correcting the minute deviation will be explained below using FIG. 15.

As described above, if a shift occurs between the imaging devices during continuous construction, a difference may occur in the pitch between the tabs of the substrate S having a known pitch. The control unit CNT periodically measures this known pitch between tabs to detect specific displacement due to factors such as heat of the imaging device. The control unit CNT also detects specific displacement due to factors such as heat of the imaging device by periodically measuring the distance between the markers SMRK on the known chute SCT.

When this displacement is detected, the control unit CNT recalculates a projective transformation matrix or an affine transformation matrix for synthesizing and transforming images using feature markers such as positioning target marks TM on the substrate S. At this time, although the obtained projective transformation matrix and affine transformation matrix can connect images, as shown in FIG. 15(a), the image space and the real space may not be matched. Therefore, the control unit CNT uses the marker SMRK on the chute SCT that was initially measured, and re-converts the coordinates based on the marker SMRK. As a result, a composite image as shown in FIG. 15(b) is obtained.

Note that the magnification changes depending on the thickness of the substrate P (height of the top surface of the substrate P), and if the height changes, alignment becomes difficult. A method for reducing the influence of the substrate thickness will be explained using FIGS. 16 and 17.

FIG. 16 is a diagram illustrating a method of changing the height of the calibration plate, FIG. ) is a sectional view showing vertical movement of the calibration plate. FIG. 17 is a diagram illustrating markers provided on the chute, FIG. 17(a) is a cross-sectional view showing a state in which the substrate is transported and placed on the attachment stage, and FIG. 17(b) is a diagram illustrating markers provided on the chute. FIG. 17(b) is a top view of a chute provided with markers, and FIG. 17(b) is a cross-sectional view of a chute provided with markers in another example.

In order to cope with the height displacement, the control unit CNT slightly moves the calibration plate CP up and down to obtain a projective transformation matrix for each height. The control unit CNT calculates the expected height of the alignment pattern position and inspection field position from the known substrate thickness, paste height, die thickness, etc., and automatically selects which projective transformation matrix held for each height is used. do. The control unit CNT recognizes the same point on the substrate in the overlapping area between adjacent imaging devices and measures the height. The control unit CNT automatically selects a projective transformation matrix to be used from the measured values.

Specifically, during the first correction using the calibration plate CP, as shown in FIG. 16(b), the attachment stage AS on which the calibration plate CP is installed is moved up and down, and the coordinates of the intersection of the calibration plates CP are determined. is measured for each height of attachment stage AS. The up and down mechanism of the attachment stage is configured to be able to move up and down in μm units.

Furthermore, it is preferable that the marker SMRK placed on the chute SCT be at the same height as the top surface of the substrate P. As shown in FIGS. 17(a) and 17(b), for example, holes having different depths and diameters are formed in the chute SCT. Holes indicating markers SMRK may be provided individually for each depth, as shown in FIG. 17(c). Marker SMRK does not need to be a hole as long as the height matches the top surface of substrate P.

According to the embodiment, it has one or more of the following effects.
(a) Since each object to be imaged can be viewed from almost directly above, it is possible to prevent tilting of the image in the height direction at the edge of the field of view, which occurs with a simple low-magnification optical system.
(b) It is possible to detect the inherent displacement of the imaging device due to factors such as heat, and it is possible to perform corrections between the imaging devices while the die bonder is operating, so it is possible to reduce the influence of the temporal displacement of the imaging device. It is.
(c) It is possible to cope with height displacement and is not affected by changes in thickness depending on the type of substrate, so it is possible to reduce the influence of differences in type.
(d) By using at least one of the above (a) to (c), it is possible to stabilize positioning accuracy and stabilize inspection.

<Modified example>
Typical modified examples of the embodiment will be illustrated below. In the following description of the modified example, the same reference numerals as in the above-described embodiment may be used for parts having the same configuration and function as those described in the above-described embodiment. As for the explanation of such portions, the explanation in the above-mentioned embodiments may be used as appropriate within the scope that is not technically contradictory. Moreover, a part of the above-described embodiments and all or part of the modified examples may be applied in combination as appropriate within a technically consistent range.

FIG. 18 is a perspective view illustrating multiple imaging devices in a modified example. In the embodiment, an example has been described in which one row of imaging objects in the width direction of the substrate S is imaged by a plurality of imaging devices, but a plurality of imaging devices are also arranged in the length direction of the substrate S, that is, a plurality of The imaging devices may be arranged in a grid pattern to image multiple rows of objects to be imaged.

For example, as shown in FIG. 18, four rows of imaging device groups CM10 to CM40 are arranged, each imaging device group has four imaging devices CM1 to CM4 of the embodiment arranged in one row, and sixteen The imaging devices on the stand are arranged in a grid pattern. Here, on the substrate S, five rows of six imaging target parts are arranged, and the imaging fields of adjacent imaging devices overlap.

As shown in FIG. 18, not only all the objects to be imaged in the first row of the substrate S, but also all the objects to be imaged in the second and subsequent rows are imaged in parallel, and the combined image is recognized. Therefore, it is possible to reduce the number of times the substrate S is moved and imaged than in the embodiment.

An example to which the above-described embodiment is applied will be described below. FIG. 19 is a top view schematically showing the die bonder in the example. FIG. 20 is a diagram illustrating the operation of the pickup head and the bonding head when viewed from the direction of arrow A in FIG. 19.

The die bonder 10 is roughly divided into a die supply section 1 that supplies the die D to be mounted on the substrate S, a pickup section 2, an intermediate stage section 3, a preform section 9, a bonding section 4, a transport section 5, It has a substrate supply section 6, a substrate unloading section 7, and a control section 8 that monitors and controls the operation of each section. The Y-axis direction is the front-rear direction of the die bonder 10, and the X-axis direction is the left-right direction. A die supply section 1 is arranged on the front side of the die bonder 10, and a bonding section 4 is arranged on the back side. Here, a plurality of product areas (hereinafter referred to as package areas P) are formed on the substrate S, which will become the final package. For example, if the substrate S is a lead frame, the package area P has a tab on which the die D is placed.

First, the die supply unit 1 supplies the die D to be mounted on the package area P of the substrate S. The die supply unit 1 includes a wafer holding table 12 that holds the wafer 11 and a peeling unit 13 shown by a dotted line that pushes up the die D from the wafer 11. The die supply unit 1 is moved in the XY-axis directions by a drive means (not shown), and moves the die D to be picked up to the position of the peeling unit 13.

The pickup section 2 includes a pickup head 21 that picks up the die D, a pickup head Y drive section 23 that moves the pickup head 21 in the Y-axis direction, and various drives (not shown) that move the collet 22 up and down, rotated, and moved in the X-axis direction. and a wafer recognition camera 24 that grasps the pickup position of the die D to be picked up from the wafer 11. The pickup head 21 has a collet 22 (see also FIG. 14) that attracts and holds the pushed-up die D at its tip, picks up the die D from the die supply section 1, and places it on the intermediate stage 31. The pickup head 21 has drive units (not shown) that move the collet 22 up and down, rotate it, and move it in the X-axis direction.

The intermediate stage section 3 includes 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 preform section 9 includes a syringe 91, a drive section 93 that moves the syringe 91 in the Y direction and the Z direction, and an adhesive recognition camera 94 as an imaging device that detects the application position of the syringe 91 and the like. Here, the adhesive recognition camera 94 is, for example, the multiple imaging devices CM1 to CM4 of the embodiment, and each of the imaging devices CM1 to CM4 is configured to take an image using a lighting device LD. The preform section 9 applies a paste adhesive such as epoxy resin to the substrate S transported by the transport section 5 using a syringe 91 . The syringe 91 has a paste adhesive sealed therein, and is configured such that the paste adhesive is pushed out from the nozzle tip and applied onto the substrate S by air pressure. If the substrate S is, for example, a multi-lead frame in which a plurality of unit lead frames are arranged in a horizontal row and connected in series, a paste adhesive is applied to each tab of the unit lead frame.

The bonding unit 4 picks up the die D from the intermediate stage 31 and bonds it onto the package area P on which the paste adhesive of the substrate S being conveyed is applied. The bonding section 4 includes a bonding head 41 including a collet 42 (see also FIG. 20) that attracts and holds the die D at the tip, similar to the pickup head 21, and a Y drive section 43 that moves the bonding head 41 in the Y-axis direction. It has a board recognition camera 44 that takes an image of a position recognition mark (not shown) in the package area P of the board S and recognizes the bonding position. Here, the board recognition camera 44 is, for example, the multiple imaging devices CM1 to CM4 of the embodiment, and each of the imaging devices CM1 to CM4 is configured to take an image using a lighting device LD. With such a configuration, the bonding head 41 corrects the pickup position and posture based on the imaged data of the stage recognition camera 32, picks up the die D from the intermediate stage 31, and picks up the substrate based on the imaged data of the substrate recognition camera 44. Bond D to the die D.

The transport unit 5 includes 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 is moved by driving a nut (not shown) of a 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 is moved from the substrate supply section 6 along the transport lane 52 to the bonding position, and after bonding, is moved to the substrate unloading section 7 and is delivered to the substrate unloading section 7.

Next, the configuration of the die supply section 1 will be explained using FIG. 21. FIG. 21 is a schematic cross-sectional view showing the main parts of the die supply section of FIG. 19.

The die supply unit 1 includes a wafer holding table 12 that moves in the horizontal direction (XY axis direction) and a peeling unit 13 that moves in the vertical direction. The wafer holding table 12 includes an expand ring 15 that holds the wafer ring 14, and a support ring 17 that horizontally positions the dicing tape 16 fixed to the wafer ring 14. The dies D diced into a mesh shape on the wafer 11 are adhesively fixed to a dicing tape 16 . The peeling unit 13 is arranged inside the support ring 17.

The die supply unit 1 lowers the expand ring 15 holding the wafer ring 14 when pushing up the die D. As a result, the dicing tape 16 held by the wafer ring 14 is stretched, increasing the distance between the dies D, and the peeling unit 13 pushes up or horizontally moves the dicing tape 16 from below the dies D to pick up the dies D. Improving sexuality.

As shown in FIG. 22, the control system 80 includes a control section 8, a drive section 86, a signal section 87, and an optical system 88. The control section 8 is roughly divided into a control/arithmetic unit 81 mainly composed of a CPU (Central Processor Unit), a storage device 82, an input/output device 83, a bus line 84, and a power supply section 85. The storage device 82 includes a main storage device 82a made up of a RAM that stores processing programs, etc., and an auxiliary storage device 82b made up of an HDD that stores control data, image data, etc. necessary for control. and has. The input/output device 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 device 83d that captures image data from the optical system 88. and has. The input/output device 83 also includes a motor control device 83e that controls a drive section 86 such as an XY table (not shown) of the die supply section 1 and a ZY drive axis of the bonding head table, and a motor control device 83e that controls various sensor signals, a lighting device, etc. It has an I/O signal control device 83f that takes in or controls signals from a signal unit 87 such as a switch. The optical system 88 includes the wafer recognition camera 24, adhesive recognition camera 94, stage recognition camera 32, and substrate recognition camera 44 shown in FIG. The control/calculation device 81 takes in necessary data via the bus line 84, performs calculations, 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 the substrate S, inspect the application pattern of the paste adhesive, and inspect the surfaces of the die D and the substrate S. Based on the positions of the die D and the substrate S calculated by the control/arithmetic device 81, the drive unit 86 is moved by software via the motor control device 83e. Through this process, the die D on the wafer 11 is positioned, and the die D is bonded onto the substrate S by operating the drive unit of the die supply section 1 and the die bonding section 4. The recognition camera used in the optical system 88 is a gray scale camera, a color camera, etc., and converts the light intensity into numerical values.

Next, a method for manufacturing a semiconductor device using the die bonder according to the example will be described using FIG. 23. FIG. 23 is a flowchart showing a method of manufacturing a semiconductor device using the die bonder of FIG. 19.

(Step S51: Wafer/substrate loading process)
The wafer ring 14 holding the dicing tape 16 to which the die D divided from the wafer 11 is attached is stored in a wafer cassette (not shown) and carried into the die bonder 10. The control section 8 supplies the wafer rings 14 to the die supply section 1 from the wafer cassette filled with the wafer rings 14 . Further, a substrate S is prepared and carried into the die bonder 10. The control section 8 attaches the substrate S to the substrate transport claw 51 using the substrate supply section 6 .

(Step S52: Pick-up process)
The control unit 8 moves the wafer ring 14 so that the wafer holding table 12 can pick up a desired die D from the wafer ring 14, and performs positioning and surface inspection based on data captured by the wafer recognition camera 24. The control unit 8 causes the peeling unit 13 to peel the positioned die D from the dicing tape 16 .

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 and held by the collet 22 of the pickup head 21, and is transported to the next process (step BS13). Then, when the collet 22 that has transported the die D to the next process returns to the die supply section 1, the next die D is peeled off from the dicing tape 16 according to the above-described procedure. The dies D are peeled off one by one.

(Step S53: Bonding process)
The control unit 8 uses the adhesive recognition camera 94 to obtain an image of the surface of the substrate S before application, and confirms the surface to which the paste adhesive is to be applied. If there is no problem with the surface to be coated, the control unit 8 applies the paste adhesive from the syringe 91 to the substrate S transported by the transport unit 5. If the board S is a multi-lead frame, paste adhesive is applied to all the tabs. After application, the control unit 8 uses the adhesive recognition camera 94 to check again whether the paste adhesive has been applied accurately, and inspects the applied paste adhesive. If there is no problem with the coating, the control unit 8 transports the substrate S to the bonding stage BS by the transport unit, and performs positioning based on image data captured by the board recognition camera 44.

The control unit 8 places the die D picked up from the wafer 11 by the pickup head 21 on the intermediate stage 31, 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 inspects whether the die D is bonded at a desired position based on the image data captured by the board recognition camera 44.

(Step S54: Board unloading process)
The control unit 8 takes out the substrate S to which the die D is bonded from the substrate transport claw 51 in the substrate unloading unit 7 . The substrate S is carried out from the die bonder 10.

Although the invention made by the present disclosers has been specifically explained based on the embodiments, modifications, and examples, the present disclosure is not limited to the above-described embodiments, modifications, and examples; Needless to say, it can be changed.

For example, in the embodiment, an example was described in which a paste adhesive is applied to the substrate in the preform section, but the adhesive for bonding the die to the substrate is applied to the wafer 11 instead of the paste adhesive applied by the syringe 91. A film-like adhesive material called a die attach film (DAF) may be used, which is attached between the dicing tape 16 and the dicing tape 16 . DAF is suitable for a stacked package in which a number of dies are placed on top of each other on a substrate S.

Further, in the embodiment, an intermediate stage section 3 is provided between the die supply section 1 and the bonding section 4, and the die D picked up from the die supply section 1 by the pickup head 21 is placed on the intermediate stage 31. In the example described above, the die D is picked up again from the intermediate stage 31 and bonded to the substrate S that has been transported. good.

10: Die bonder (die bonding equipment)
AA: Attachment area CM1 to CM4: Imaging device CNT: Control unit S: Substrate SCT: Chute (transport path)

Claims (23)

a conveyance path for conveying the substrate;
a plurality of imaging devices fixedly arranged in a line above the transport path along the width direction of the substrate;
A plurality of attachment areas located on the substrate in a row along the width direction are captured by the plurality of imaging devices to obtain a plurality of images, and a composite image is generated based on the plurality of images obtained. , a control unit configured to recognize an imaged object in the attachment area based on the composite image;
Equipped with
A die bonding apparatus in which the imaging fields of each imaging device overlap on the substrate, and the overlapping imaging fields are larger than the attachment area. The die bonding apparatus according to claim 1,
The die bonding apparatus is configured such that the control unit generates the composite image based on coordinate markers located in the overlapping imaging field of view. The die bonding apparatus according to claim 2,
The coordinate marker is a grid-like scale that covers the field of view of all the imaging devices,
The control unit projects the coordinate markers, projectively transforms the image based on the same intersection of the coordinate markers that fall within the overlapped imaging field of view, and connects the images between the imaging devices to generate the composite image. A die bonding device configured as follows. The die bonding apparatus according to claim 3,
The transport path has a plurality of reference markers on the outside of both ends of the substrate in the width direction, and
The substrate has a plurality of tabs arranged at predetermined intervals,
The die bonding apparatus is configured such that the control unit measures the interval between the tabs or the interval between the reference markers with the imaging device, and detects a displacement between the imaging devices. The die bonding apparatus according to claim 4,
The substrate further includes a feature marker,
The die bonding apparatus is configured such that, when a displacement between the imaging devices is detected, the control unit recalculates a projective transformation matrix for synthesizing and transforming images based on the feature marker. The die bonding apparatus according to claim 5,
The die bonding apparatus is configured such that the control unit recalculates the projective transformation matrix based on the coordinates of the reference marker measured in advance. The die bonding apparatus according to claim 6,
The control unit slightly moves the substrate up and down to obtain a projective transformation matrix for each height,
An expected height of the alignment pattern position or inspection field position is calculated from the thickness of the substrate, paste height, or die thickness, and which of the projective transformation matrices is maintained for each height based on the calculated expected height. A die bonding device configured to select either of the following: The die bonding apparatus according to claim 7,
The control unit recognizes the same point on the substrate in overlapping imaging fields of view between adjacent imaging devices, measures the height, and holds the same point for each height based on the measured height. A die bonding apparatus configured to select the projective transformation matrix. The die bonding apparatus according to any one of claims 1 to 8,
Furthermore, it includes a plurality of illumination devices provided corresponding to each of the plurality of imaging devices,
The die bonding apparatus is configured such that the control unit independently controls the light of the plurality of lighting devices. The die bonding apparatus according to any one of claims 1 to 8,
The die bonding apparatus is configured such that the control unit transports the substrate in the length direction of the substrate and images the plurality of attachment areas in the next row with the plurality of imaging devices. The die bonding apparatus according to any one of claims 1 to 8,
In the die bonding apparatus, the object to be imaged is a paste adhesive applied to the substrate. The die bonding apparatus according to claim 11,
The die bonding apparatus is configured such that the control unit performs an appearance inspection of the paste adhesive applied to the substrate using the imaging device. The die bonding apparatus according to any one of claims 1 to 8,
A die bonding apparatus, wherein the imaged object is a die bonded on the substrate or an already bonded die. A transport path for transporting a substrate having a plurality of attachment areas, a plurality of imaging devices fixedly arranged in a line above the transport path along the width direction of the substrate, and corresponding to each of the plurality of imaging devices. a plurality of illumination devices provided as a die bonding device, wherein the imaging field of each imaging device overlaps on the substrate, and the overlapping imaging field of view is configured to be larger than the attachment area. A process of loading the board,
acquiring a plurality of images by capturing images of the plurality of attachment regions in a row along the width direction located on the substrate with the plurality of imaging devices, and generating a composite image based on the plurality of acquired images. and a step of recognizing an imaged object in the attachment area based on the composite image;
transporting the substrate in the length direction of the substrate and imaging a plurality of attachment areas in the next row with the plurality of imaging devices;
A method for manufacturing a semiconductor device comprising: The method for manufacturing a semiconductor device according to claim 14,
A method for manufacturing a semiconductor device, wherein the composite image is generated based on coordinate markers located in the overlapping imaging field of view. The method for manufacturing a semiconductor device according to claim 15,
The coordinate marker is a grid-like scale that covers the field of view of all the imaging devices,
A method for manufacturing a semiconductor device, which projects the coordinate markers, projectively transforms the image based on the same intersection of the coordinate markers that fall into the overlapping imaging field, and connects the images between the respective imaging devices to generate the composite image. . The method for manufacturing a semiconductor device according to claim 16,
The transport path has a plurality of reference markers on the outside of both ends of the substrate in the width direction, and
The substrate has a plurality of tabs arranged at predetermined intervals,
A method for manufacturing a semiconductor device, wherein the interval between the tabs or the interval between the reference markers is measured by the imaging device, and displacement between the imaging devices is detected. The method for manufacturing a semiconductor device according to claim 17,
The substrate further includes a feature marker,
A method for manufacturing a semiconductor device, wherein when a displacement between the imaging devices is detected, a projective transformation matrix for synthesizing and transforming images is recalculated based on the feature marker. The method for manufacturing a semiconductor device according to claim 18,
A method for manufacturing a semiconductor device, wherein the projective transformation matrix is recalculated based on the coordinates of the reference marker measured in advance. The method for manufacturing a semiconductor device according to claim 19,
Slightly move the substrate up and down to obtain a projective transformation matrix for each height,
An expected height of the alignment pattern position or inspection field position is calculated from the thickness of the substrate, paste height, or die thickness, and which of the projective transformation matrices is maintained for each height based on the calculated expected height. A semiconductor device manufacturing method to choose from. The method for manufacturing a semiconductor device according to claim 20,
The projective transformation matrix that recognizes the same point on the substrate in overlapping imaging fields of view between adjacent imaging devices, measures the height, and holds each height based on the measured height. A manufacturing method for semiconductor devices that selects. The method for manufacturing a semiconductor device according to any one of claims 14 to 21,
Furthermore, the step of applying a paste adhesive to the substrate,
The method for manufacturing a semiconductor device, wherein the object to be imaged is the applied paste adhesive. The method for manufacturing a semiconductor device according to any one of claims 14 to 21,
further comprising the step of bonding a die onto the substrate or already bonded die;
The method for manufacturing a semiconductor device, wherein the imaged object is the bonded die.

Images