Mounting device, mounting method, and mounting control program

Abstract

To provide a mounting device which can accurately decide a target position at which each mounting body is mounted by using an imaging unit that adopts a Scheimpflug optical system even when a temperature of a peripheral environment changes or the plurality of mounting bodies such as a semiconductor chip are mounted in a superimposed manner, and can place and mount the mounting body at the target position on a substrate or the other mounting body.SOLUTION: A mounting control unit recognizes a reference position of a mounting body on the basis of a look-up image output by making a look-up imaging unit image a mounting surface by adjusting a position of a mounting tool such that an index surface of a calibration index arranged in such a manner that it can be imaged by the look-up imaging unit and an overlooking imaging unit that adopts a Scheimpflug optical system and the mounting surface of the mounting body have the same height, adjusts a position of a stage such that a mounting object surface of a placement planned area has the same height as the index surface, and mounts the mounting surface on the mounting object surface on the basis of the recognized reference position.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a mounting device, a mounting method, and a mounting control program. [Background technology]

[0002] In a conventional bonding apparatus, one example of a mounting device, the workpiece, such as a die pad, is first imaged from directly above with a camera to confirm its position. Then, the camera is retracted, and the head supporting the bonding tool is moved directly above the workpiece to perform the bonding work. Bonding apparatuses employing this configuration not only require a long working time, but also suffer from the problem of accumulating movement errors relative to the target work position. Therefore, the use of an imaging unit employing a shineproof optical system that can image the workpiece from an oblique direction has been considered (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2014-179560 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, it has become clear that imaging units employing a Shineproof optical system are prone to exhibiting minute displacements of optical elements due to ambient temperature changes as planar displacements in the output image, due to the structural characteristics of the optical system. Planar displacements in the output image cause errors in calculating the target position where the semiconductor chip should be placed, and therefore hinder the accurate mounting of the semiconductor chip to its intended target position. In particular, in so-called stacked die mounting and 2.5D mounting, where one semiconductor chip is mounted on top of another semiconductor chip mounted on a substrate, the height of the mounting surface on which each semiconductor chip is placed changes. In such cases, it has become clear that the amount of error differs depending on the height.

[0005] The present invention was made to solve these problems, and provides a mounting apparatus that can accurately determine the target position for each mounting object using an imaging unit employing a shineproof optical system, even when the ambient temperature changes, or when multiple mounting objects such as semiconductor chips are stacked, and can then mount the mounting object by placing it at the target position on a substrate or on another mounting object. [Means for solving the problem]

[0006] The mounting device according to the first aspect of the present invention picks up and holds a mounted body having a mounting surface, and mounts the mounting surface on a planned mounting area set for a substrate placed on a stage or another mounted body already mounted on the substrate. An imaging unit for overhead imaging for imaging the planned mounting area from the same side as the mounting tool with respect to the stage surface, an imaging unit for overhead imaging for imaging the mounted body held by the mounting tool from the opposite side to the overhead imaging unit with respect to the stage surface, a calibration index arranged so as to be imaged by the overhead imaging unit and the overhead imaging unit, and the mounting surface is the same height as the index surface of the calibration index. Based on the overhead image obtained by adjusting the position of the mounting tool and imaging and outputting the mounting surface to the overhead imaging unit, the reference position of the mounted body is recognized, the position of the stage is adjusted so that the mounting surface of the planned mounting area is the same height as the index surface, and the mounting is performed on the mounting surface based on the reference position. And a mounting control unit.

[0007] Also, the mounting method according to the second aspect of the present invention picks up and holds a mounted body having a mounting surface, and mounts the mounting surface on a planned mounting area set for a substrate placed on a stage or another mounted body already mounted on the substrate. An imaging unit for overhead imaging for imaging the planned mounting area from the same side as the mounting tool with respect to the stage surface, an imaging unit for overhead imaging for imaging the mounted body held by the mounting tool from the opposite side to the overhead imaging unit with respect to the stage surface, and a calibration index arranged so as to be imaged by the overhead imaging unit and the overhead imaging unit. The position of the mounting tool is adjusted so that the mounting surface is the same height as the index surface of the calibration index, and the reference position of the mounted body is recognized based on the overhead image obtained by imaging and outputting the mounting surface to the overhead imaging unit. Adjust the position of the stage so that the mounting surface of the planned mounting area is the same height as the index surface, and a mounting control step of mounting on the mounting surface based on the reference position.

[0008] In addition, the mounting control program in the third aspect of the present invention picks up and holds a mounting body having a mounting surface, and mounts the mounting surface to a planned mounting area set for a substrate placed on a stage or another mounting body already mounted on the substrate. A mounting tool, an overhead imaging unit for imaging the planned mounting area from the same side as the mounting tool with respect to the stage surface, where the optical system and the imaging element are arranged to satisfy the shine-proof condition so that a plane parallel to the stage surface of the stage becomes the focal plane, and an elevation imaging unit for imaging the mounting body held by the mounting tool from the side opposite to the overhead imaging unit with respect to the stage surface, and a calibration index arranged to be imaged by the overhead imaging unit and the elevation imaging unit. A mounting control program for controlling a mounting device, which adjusts the position of the mounting tool so that the mounting surface is at the same height as the index surface of the calibration index, causes the elevation imaging unit to image the mounting surface and outputs an elevation image, and based on the elevation image, recognizes the reference position of the mounting body, adjusts the position of the stage so that the mounting surface of the planned mounting area is at the same height as the index surface, and causes a computer to execute a mounting control step of mounting on the mounting surface based on the reference position.

Effects of the Invention

[0009] According to the present invention, even when the temperature of the surrounding environment changes, or when mounting a plurality of stacked mounting bodies such as semiconductor chips, the target position for mounting each mounting body is accurately determined using an imaging unit employing a shine-proof optical system, and a mounting device or the like that can mount the mounting body on the target position on a substrate or another mounting body can be provided.

Brief Description of the Drawings

[0010] [Figure 1] It is an overall configuration diagram of a flip chip bonder including a bonding device according to the present embodiment. [Figure 2] It is a system configuration diagram of the bonding device. [Figure 3] It is an explanatory diagram for explaining a shine-proof optical system. [Figure 4] This diagram shows how three imaging units capture calibration indicators. [Figure 5] This diagram shows how the bonding tool picks up the first semiconductor chip. [Figure 6] This figure shows the third imaging unit imaging the first semiconductor chip and adjusting the height of the first region surface to the height of the index surface. [Figure 7] This diagram schematically shows the upward-view image output by the third imaging unit. [Figure 8] This diagram shows the first and second imaging units imaging the lead frame, which is the area where the device is to be mounted. [Figure 9] This is a partial perspective view of Figure 8. [Figure 10] This diagram shows the procedure for calculating the target coordinates on the die pad on which the first semiconductor chip will be mounted, based on the first and second overhead images. [Figure 11] This diagram shows how a bonding tool places the first semiconductor chip into the target position and performs bonding. [Figure 12] This diagram shows the bonding tool being retracted. [Figure 13] This figure shows the third imaging unit imaging the second semiconductor chip and adjusting the height of the second region surface to the height of the index surface. [Figure 14] This diagram schematically shows the upward-view image output by the third imaging unit. [Figure 15] This diagram shows the first imaging unit and the second imaging unit imaging the first semiconductor chip, which is the area where it is to be mounted. [Figure 16] This diagram shows the procedure for calculating the target coordinates on the first semiconductor chip on which the second semiconductor chip will be mounted, based on the first and second overhead images. [Figure 17] This diagram shows how a bonding tool places the second semiconductor chip into the target position and performs bonding. [Figure 18] This is a flowchart illustrating the semiconductor chip bonding procedure. [Figure 19] This is a subflow diagram illustrating the procedure for the calibration control step. [Figure 20] This is a subflow diagram illustrating the procedure for the bonding control step. [Figure 21] This figure shows how three imaging units capture calibration indicators in another embodiment. [Figure 22] This is a flowchart illustrating the semiconductor chip bonding procedure in another embodiment. [Figure 23] This flowchart illustrates additional steps related to further modifications. [Modes for carrying out the invention]

[0011] The present invention will be described below through embodiments of the invention, but the invention claimed is not limited to the following embodiments. Furthermore, not all of the configurations described in the embodiments are necessarily essential as means to solve the problem. In each figure, if there are multiple structures having the same or similar configuration, in order to avoid complexity, some parts may be labeled with reference numerals, while others may not be labeled with the same reference numerals.

[0012] Figure 1 is an overall configuration diagram of a flip-chip bonder including a bonding apparatus 100 as a mounting apparatus according to this embodiment. The flip-chip bonder mainly consists of a bonding apparatus 100 and a chip supply apparatus 500. The chip supply apparatus 500 is a device that supplies diced semiconductor chips 310 as mounting bodies to the bonding apparatus 100 by placing them on its upper surface. Specifically, the chip supply apparatus 500 includes a pickup mechanism 510 and an inversion mechanism 520. The pickup mechanism 510 is a device that pushes up any placed semiconductor chip 310 toward the inversion mechanism 520. The inversion mechanism 520 is a device that picks up the semiconductor chip 310 pushed up by the pickup mechanism 510 and inverts it, thereby changing its orientation in the vertical direction. In this embodiment, two types of semiconductor chips 310 are provided: a first semiconductor chip 310a and a second semiconductor chip 310b. The bonding apparatus 100 is a device that picks up the first semiconductor chip 310a or the second semiconductor chip 310b, which is adsorbed in an inverted state by the inversion mechanism 520, using a bonding tool 120 (described later), and stacks and bonds them onto the lead frame 330. In this embodiment, the first semiconductor chip 310a is placed on the lead frame 330 and bonded, and the second semiconductor chip 310b is stacked on top of the first semiconductor chip 310a and bonded. The lead frame 330 is an example of a substrate placed on the stage 190.

[0013] The bonding apparatus 100 mainly comprises a head unit 110, a bonding tool 120, a first imaging unit 130, a second imaging unit 140, a third imaging unit 150, a calibration unit 170, and a stage 190. The head unit 110 supports the bonding tool 120, the first imaging unit 130, and the second imaging unit 140, and is movable in the planar and vertical directions by a head drive motor 111. In this embodiment, the planar direction is the horizontal direction defined by the X-axis and Y-axis directions, as shown in the figure, and the vertical direction (height direction) is the Z-axis direction which is perpendicular to the X-axis and Y-axis directions.

[0014] The bonding tool 120 is movable in the height direction relative to the head portion 110 by a tool drive motor 121, and is also rotatable around the Z axis. The bonding tool 120 is an example of a mounting tool and has a collet 122 at its tip for adsorbing a semiconductor chip 310 and a heater 124 for heating the semiconductor chip 310 that the collet 122 adsorbs. The bonding tool places the semiconductor chip 310, which has been adsorbed onto the collet 122, in a predetermined position, and bonds it by applying pressure with the tip of the collet 122 and heating it with the heater 124.

[0015] The first imaging unit 130 and the second imaging unit 140 are overhead imaging units that capture images of the lead frame 330 from an overhead perspective. The first imaging unit 130 comprises a first optical system 131 and a first image sensor 132, and is obliquely mounted on the head unit 110 with its optical axis directed downwards from the bonding tool 120. The first optical system 131 and the first image sensor 132 are arranged to satisfy the shine proof condition such that the plane parallel to the stage surface 190a of the stage 190 becomes the focal plane 110a.

[0016] The second imaging unit 140 comprises a second optical system 141 and a second image sensor 142, and is obliquely mounted on the head portion 110 with its optical axis directed downward from the bonding tool 120, on the opposite side from the first imaging unit 130 with respect to the bonding tool 120. The second optical system 141 and the second image sensor 142 are arranged to satisfy the Scheinproof condition such that the plane parallel to the stage surface 190a of the stage 190 becomes the focal plane 110a. In the following description, the first imaging unit 130 and the second imaging unit 140 may be collectively referred to as the "overhead imaging unit."

[0017] The third imaging unit 150 is an upward-viewing imaging unit for imaging the semiconductor chip 310, which is held in the collet 122 of the bonding tool 120, by viewing it upwards. As shown in the figure, the third imaging unit 150 is located in the space opposite to the space where the overhead-viewing imaging unit is located, if the stage surface 190a of the stage 190 is used as the dividing surface. The third imaging unit 150 comprises a third optical system 151 and a third image sensor 152, and is installed with its optical axis facing upwards. The third imaging unit 150 is a general imaging unit in which the third optical system 151 and the third image sensor 152 are arranged perpendicular to the optical axis, and its focal plane 150a is parallel to the light-receiving surface of the third image sensor 152. In the following description, the third imaging unit 150 may be referred to as the "upward-viewing imaging unit".

[0018] The calibration unit 170 mainly comprises an index drive motor 171, an index plate 172, and a calibration index 173. The calibration index 173 is a reference mark with a defined reference position, such as the intersection of a cross mark. The index plate 172 is, for example, a thin plate of glass or transparent resin, with the calibration index 173 printed on one side thereof. That is, the calibration index 173 can be observed from any side of the index plate 172. In this embodiment, the calibration index 173 is printed on the surface of the index plate 172 opposite to the surface facing the third imaging unit 150. In this embodiment, the surface on which the calibration index 173 is printed is referred to as the index surface 173a.

[0019] Note that the indicator plate 172 does not need to be transparent, as long as the two calibration indices 173 are printed on both sides of the indicator plate 172 without any shift in their respective reference positions in the XY direction. In that case, the thickness of the indicator plate 172 is set so that the calibration indice 173 facing the third imaging unit 150 falls within the depth of field range of the third imaging unit 150. Furthermore, the calibration indices 173 are not limited to printing; they may also be provided by attaching stickers or marking the surface of the indicator plate 172. When calibration indices 173 are provided on both sides of the indicator plate 172, it is preferable to designate the surface opposite to the surface facing the third imaging unit 150 as the indicator surface 173a. The error in the Z direction due to the difference between the calibration indices 173 imaged by the first imaging unit 130 and the second imaging unit 140 and the calibration indice 173 imaged by the third imaging unit 150 can be corrected based on the thickness of the indicator plate 172, etc.

[0020] The indicator drive motor 171 rotates the indicator plate 172 around the Z-axis, thereby moving the calibration indicator 173 to or from the vicinity of the center of the field of view of the third imaging unit 150. When the indicator plate 172 is rotated and the calibration indicator 173 is brought into the field of view of the third imaging unit 150, the positions of each are adjusted so that the calibration indicator 173 becomes the focal plane 150a of the third imaging unit 150. Since the third optical system 151 has a depth of field of a certain depth range that encloses the focal plane 150a, a misalignment between the indicator plane 173a and the focal plane 150a is permissible as long as it is within that depth of field range.

[0021] The stage 190 is movable in both planar and vertical directions by the stage drive motor 191. Specifically, as will be described later, the stage 190 is positioned such that the first region surface 330a (the upper surface of the lead frame 330), which is the region surface of the area where the first semiconductor chip 310a is to be placed, and the second region surface 330b (the upper surface of the first semiconductor chip 310a bonded to the lead frame 330), which is the region surface of the area where the second semiconductor chip 310b is to be placed, are at the same height as the indicator surface 173a, according to the mounting process. Here, the first region surface 220a includes the mounting surface on which the mounting surface of the first semiconductor chip 310a is mounted. The second region surface 330b includes the mounting surface on which the mounting surface of the second semiconductor chip 310b is mounted.

[0022] Figure 2 is a system configuration diagram of the bonding apparatus 100. The control system of the bonding apparatus 100 mainly consists of a calculation processing unit 210, a storage unit 220, input / output devices 230, a first imaging unit 130, a second imaging unit 140, a third imaging unit 150, a head drive motor 111, a tool drive motor 121, a guide drive motor 171, and a stage drive motor 191.

[0023] The arithmetic processing unit 210 is a processor (CPU: Central Processing Unit) that controls the bonding apparatus 100 and executes programs. The processor may be configured to work in conjunction with an arithmetic processing chip such as an ASIC (Application Specific Integrated Circuit) or a GPU (Graphics Processing Unit). The arithmetic processing unit 210 reads the bonding control program stored in the memory unit 220 and executes various processes related to bonding control.

[0024] The memory unit 220 is a non-volatile storage medium, such as an HDD (Hard Disk Drive). In addition to the bonding control program, the memory unit 220 can store various parameter values, functions, lookup tables, etc., used for control and calculations. In particular, the memory unit 220 stores calibration data 221. The calibration data 221, as will be described in more detail later, is data relating to calibration values ​​that calibrate the difference between coordinate values ​​calculated based on an overhead image and coordinate values ​​calculated based on an upward image for the same object of observation.

[0025] The input / output device 230 includes, for example, a keyboard, mouse, and display monitor, and is a device that accepts menu operations from the user and presents information to the user. For example, the arithmetic processing unit 210 may display the acquired overhead image and upward view image on the display monitor, which is one of the input / output devices 230.

[0026] The first imaging unit 130 receives an imaging request signal from the processing unit 210, performs imaging, and transmits the first overhead image output by the first image sensor 132 to the processing unit 210 as an image signal. The second imaging unit 140 receives an imaging request signal from the processing unit 210, performs imaging, and transmits the second overhead image output by the second image sensor 142 to the processing unit 210 as an image signal. The third imaging unit 150 receives an imaging request signal from the processing unit 210, performs imaging, and transmits the upward-view image output by the third image sensor 152 to the processing unit 210 as an image signal.

[0027] The head drive motor 111 receives a drive signal from the arithmetic processing unit 210 and moves the head unit 110 in the horizontal and vertical directions. The tool drive motor 121 receives a drive signal from the arithmetic processing unit 210 and moves the bonding tool 120 in the vertical direction and rotates it around the Z-axis. The indicator drive motor 171 receives a drive signal from the arithmetic processing unit 210 and rotates the indicator plate 172. The stage drive motor 191 receives a drive signal from the arithmetic processing unit 210 and moves the stage 190 in the horizontal and vertical directions.

[0028] The arithmetic processing unit 210 also serves as a functional arithmetic unit that performs various calculations in accordance with the processing instructed by the bonding control program. The arithmetic processing unit 210 can function as an image acquisition unit 211, a drive control unit 212, a calibration control unit 213, and a bonding control unit 214. The image acquisition unit 211 transmits an imaging request signal to the first imaging unit 130, the second imaging unit 140, and the third imaging unit 150, and acquires image signals of the first overhead image, the second overhead image, and the upward-view image. The drive control unit 212 transmits drive signals according to the control amount to the head drive motor 111, the tool drive motor 121, the index drive motor 171, and the stage drive motor 191, thereby moving the head unit 110, the bonding tool 120, the index plate 172, and the stage 190 to the target position. It also transmits drive signals to the pickup mechanism 510 and the inversion mechanism 520 to push up or pick up and invert the target semiconductor chip 310.

[0029] The calibration control unit 213 calculates the above-mentioned calibration value based on the overhead image obtained by having the overhead imaging unit capture and output the calibration index 173, and the upward-view image obtained by having the upward-view imaging unit capture and output the calibration index 173, by controlling the image acquisition unit 211, the drive control unit 212, etc. The bonding control unit 214 is an example of a mounting control unit, and by controlling the image acquisition unit 211, the drive control unit 212, etc., it recognizes the reference position of the semiconductor chip 310 held by the bonding tool 120 based on the upward-view image obtained by having the upward-view imaging unit capture and output the semiconductor chip 310. At this time, the bonding control unit 214 adjusts the position of the stage 190 so that the area surface of the area where the semiconductor chip 310 is to be placed is at the same height as the index surface 173a of the calibration index 173. Then, the semiconductor chip 310 is placed on the mounting area using the bonding tool 120 so that the reference position matches the overhead image output by the overhead imaging unit, which captures the area where the semiconductor chip 310 is to be placed, and the semiconductor chip 310 is bonded to the target position determined based on the calibration value described above. At this time, the bonding control unit 214 adjusts the position of the head unit 110 so that the focal plane 110a of the overhead imaging unit is at the same height as the surface of the mounting area. The specific control and processing of the calibration control unit 213 and the bonding control unit 214 will be described in detail later.

[0030] Figure 3 is an explanatory diagram illustrating the Scheinproof optical system used in the first imaging unit 130. While the second imaging unit 140 also employs a similar Scheinproof optical system, this explanation focuses on the Scheinproof optical system of the first imaging unit 130.

[0031] In Figure 3, plane S1 is the focal plane 110a, which is parallel to the stage surface of the stage 190. The virtual plane S2 is the plane containing the main plane of the first optical system 131, which consists of the object-side lens group 131a and the image-side lens group 131b. Plane S3 is the plane containing the light-receiving surface of the first image sensor 132. In this embodiment, the Scheinproof optical system includes the first optical system 131 and the first image sensor 132, which are arranged to satisfy the Scheinproof condition. An arrangement that satisfies the Scheinproof condition is one in which plane S1, virtual plane S2, and virtual plane S3 intersect each other on a common straight line P.

[0032] The aperture 133 is positioned between the object-side lens group 131a and the image-side lens group 131b, and restricts the light beam that passes through. The diameter of the aperture 133 determines the depth of field D P This can be adjusted. Therefore, for example, if the first region surface 330a or the second region surface 330b is located within this depth of field, the first imaging unit 130 can capture images of the pad reference marks and stacked reference marks, which will be described later, in focus. In this sense, position control that adjusts the focal plane 110a to be at the same height as a certain plane is possible for the depth of field D P A deviation within this range is acceptable.

[0033] The second imaging unit 140 has the same configuration as the first imaging unit 130 and is arranged on the head portion 110 symmetrically with respect to the YZ plane containing the central axis of the bonding tool 120. Therefore, the second imaging unit 140 can also capture the pad reference marks and stacking reference marks in focus, just like the first imaging unit 130. It is preferable that the focal plane of the first imaging unit 130 and the focal plane of the second imaging unit 140 coincide at the focal plane 110a, but even if there is a misalignment, as long as a portion of their respective depths of field overlap, the pad reference marks and stacking reference marks can be captured in focus together.

[0034] Now, by employing an imaging unit with such a shine-proof optical system, the area directly beneath the bonding tool 120 can be observed from an oblique direction. Therefore, even when the bonding tool 120 holds the semiconductor chip 310 and is moved directly above the area where the chip is to be placed, the area where the chip is to be placed can be observed by the overhead imaging unit. In other words, after moving the bonding tool 120 directly above the area where the chip is to be placed, the target position for placing the semiconductor chip 310 can be determined based on the overhead image output by the overhead imaging unit. Then, since the semiconductor chip 310 only needs to be moved to the target position from that state, the movement of the head unit 110 and the bonding tool 120 can be greatly suppressed, resulting in a reduction in positional deviation due to movement and a shortening of lead time.

[0035] However, it has become clear that imaging units employing a Scheinproof optical system, due to the characteristics of the optical system and image sensor arrangement, will experience a planar displacement of the output image even with slight displacement of the optical system or image sensor due to changes in the ambient temperature. In other words, it has become clear that the image shifts depending on the ambient temperature. This phenomenon causes errors in the target position when determining the target position for mounting the semiconductor chip 310 based on an overhead image, resulting in the inability to accurately bond the semiconductor chip to its original target position. In particular, when the heater 124 for heating the semiconductor chip 310 is attached to the bonding tool 120, the temperature change around the Scheinproof optical system becomes larger. Furthermore, in so-called stacked die mounting or 2.5D mounting, where another semiconductor chip is layered and bonded on top of a semiconductor chip bonded to a substrate, the height of the mounting surface on which each semiconductor chip is placed changes. In such cases, it has become clear that the amount of error differs depending on the height.

[0036] Therefore, in this embodiment, the calibration process is performed at a predetermined timing when a change in the ambient temperature is expected, and in the bonding process, the height of the region surface (first region surface 330a or second region surface 330b) of the area where the semiconductor chip 310 to be mounted is to be placed is aligned with the height of the index surface 173a of the calibration index 173, so that the calibration value obtained by the calibration process can be applied to the target position recognition of the semiconductor chip 310 to be stacked in any layer. The calibration process and the bonding process will be described in order below.

[0037] The calibration process is performed by the calibration control unit 213. First, the calibration control unit 213 instructs the first imaging unit 130, the second imaging unit 140, and the third imaging unit 150 to image the calibration index 173. Figure 4 shows the three imaging units imaging the calibration index 173.

[0038] As shown in the figure, when the calibration control unit 213 starts the calibration process, it drives the index drive motor 171 via the drive control unit 212 to move the index plate 172 into the field of view of the third imaging unit 150. When the index plate 172 is moved into the field of view of the third imaging unit 150, the calibration index 173 provided on the index plate 172 is positioned approximately in the center of the field of view of the third imaging unit 150, and its index surface 173a and the focal plane 150a of the third imaging unit 150 become the same plane.

[0039] The calibration control unit 213 then drives the head drive motor 111 via the drive control unit 212 to move the head unit 110 so that the focal plane 110a of the overhead imaging unit coincides with the index plane 173a and the calibration index 173 is positioned directly below the bonding tool 120. The bonding tool 120 is retracted to a position where it does not enter the field of view of the overhead imaging unit.

[0040] In the state where each is arranged as described above, the calibration control unit 213 acquires a first bird's-eye view image from the first imaging unit 130, a second bird's-eye view image from the second imaging unit 140, and an upward view image from the third imaging unit 150 via the image acquisition unit 211. Then, from the image coordinates of the image of the calibration index 173 reflected in the first bird's-eye view image and the second bird's-eye view image respectively, the three-dimensional coordinates (X hr , Y hr , Z hr ) of the calibration index 173 are calculated. Also, from the image coordinates of the image of the calibration index 173 reflected in the upward view image, the three-dimensional coordinates (X sr , Y sr , Z sr ) of the calibration index 173 are calculated. If the imaging units for bird's-eye view are not affected by the temperature change of the surrounding environment and the coordinates between the imaging units are kept correctly adjusted in the initial state of the bonding apparatus 100, at least X hr = X sr , Y hr = Y sr should be the case.

[0041] However, as described above, after starting the use of the bonding apparatus 100 for a while, the three-dimensional coordinates calculated from the bird's-eye view image are affected by the temperature change of the surrounding environment and include errors. Therefore, the error (ΔX, ΔY) is used as the calibration value. Specifically, the error is expressed as a difference, and ΔX = X sr - X hr , ΔY = Y sr - Y hr can be set. If the calibration value is calculated in this way, and then the imaging unit for bird's-eye view images an observation target and the three-dimensional coordinates calculated from the bird's-eye view image are (X ht , Y ht , Z ht ), it can be corrected to (X ht + ΔX, Y ht + ΔY, Z ht ) taking the calibration value into account. It can be said that there is no error in the corrected coordinate value with respect to the coordinate value calculated from the upward view image that would be obtained if the same observation target could be imaged by the imaging unit for upward view.

[0042] The calibration control unit 213 stores the calibration value calculated in this way as calibration data 221 in the storage unit 220. The calibration data 221 is referenced in the bonding process described later until it is determined that the ambient temperature may have changed and that further calibration is necessary. In other words, when it is determined that further calibration is necessary, the calibration control unit 213 repeats the above process to update the calibration value.

[0043] One example of when a recalibration process is deemed necessary is when the bonding control unit 214 completes bonding a predetermined batch of semiconductor chips 310. Specifically, the calibration control unit 213 may perform the calibration process in conjunction with the timing when a new batch of semiconductor chips 310 is supplied to the chip supply device 500. Alternatively, the duration of the bonding work performed by the bonding control unit 214 may be used as a guideline. For example, the calibration process can be set to be performed when the bonding work is performed continuously for 60 minutes. Furthermore, the head unit 110 may be equipped with a temperature detection unit that detects the temperature of the overhead imaging unit, and the calibration process may be performed when the temperature detection unit detects a predetermined temperature. Specifically, multiple temperatures may be set in advance, and the calibration process may be performed when it is detected that the ambient temperature has changed to cross one of these temperatures. By updating the calibration value in this way, it becomes possible to suppress the error in the coordinate values ​​calculated from the overhead image to a certain range over the period during which the bonding process is continued.

[0044] The bonding process is carried out by the bonding control unit 214. First, the bonding control unit 214 picks up the target semiconductor chip 310. Figure 5 shows the bonding tool 120 picking up the first semiconductor chip 310a.

[0045] The bonding control unit 214 moves the head unit 110 to the top of the chip supply device 500 by driving the head drive motor 111 via the drive control unit 212, and lowers the bonding tool 120 by driving the tool drive motor 121. In parallel with this, the pickup mechanism 510 pushes up one of the first semiconductor chips 310a to be bonded from among the semiconductor chips 310 placed on the chip supply device 500 toward the inversion mechanism 520, and the inversion mechanism 520 picks up the first semiconductor chip 310a and inverts it. The lowered bonding tool 120 then picks up the first semiconductor chip 310a by picking it up with the collet 122, and raises the bonding tool 120.

[0046] When the indicator plate 172 is located within the field of view of the third imaging unit 150, the bonding control unit 214 moves the indicator plate 172 out of the field of view of the third imaging unit 150 before or after the bonding tool 120 picks up the first semiconductor chip 310a. Specifically, the bonding control unit 214 moves the indicator plate 172 by driving the indicator drive motor 171 via the drive control unit 212.

[0047] The bonding control unit 214 then causes the third imaging unit 150 to image the first semiconductor chip 310a, which has been adsorbed by the bonding tool 120. Figure 6 shows the third imaging unit 150 imaging the first semiconductor chip 310a adsorbed by the bonding tool 120, and adjusting the height of the first region surface 330a, which is the region surface of the area where the first semiconductor chip 310a is to be placed, to the height of the indicator surface 173a.

[0048] The bonding control unit 214 drives the head drive motor 111 via the drive control unit 212 to move the head unit 110 so that the focal plane 110a of the overhead imaging unit is at the same height as the indicator plane 173a, and the third imaging unit 150 is positioned directly below the bonding tool 120. Then, by driving the tool drive motor 121, the bonding tool 120 is lowered so that the contact surface of the first semiconductor chip 310a that is intended to contact the area where the lead frame 330 is to be mounted is at the same height as the indicator plane 173a. This contact surface includes the mounting surface of the first semiconductor chip 310a. Once this arrangement adjustment is complete, the bonding control unit 214 causes the third imaging unit 150 to image the contact surface of the first semiconductor chip 310a held by the bonding tool 120 via the image acquisition unit 211. The contact surface of the first semiconductor chip 310a is the surface opposite to the surface that is attracted to the collet 122, and is the surface that faces the third imaging unit 150.

[0049] The bonding control unit 214 adjusts the position of the stage 190 by driving the stage drive motor 191 via the drive control unit 212 before and after the process of causing the third imaging unit 150 to image the contact surface of the first semiconductor chip 310a. Specifically, it adjusts the stage so that the first region surface 330a, which is the region surface of the area where the first semiconductor chip 310a is to be placed, is at the same height as the index surface 173a. For example, since the thickness of the lead frame 330 is known, the bonding control unit 214 only needs to move the stage surface 190a to Z=Z1, which is the height of the index surface 173a minus the thickness of the lead frame 330.

[0050] Furthermore, if the first region surface 330a has already been adjusted to the same height as the index surface 173a, the bonding control unit 214 will skip the position adjustment of the stage 190. Alternatively, the position adjustment of the stage 190 may be performed before the bonding control unit 214 begins the process of placing the first semiconductor chip 310a in the planned mounting region.

[0051] Figure 7 schematically shows an upward-view image output by the third imaging unit 150 after imaging the first semiconductor chip 310a held by the bonding tool 120. Each subject image in the figure will be described using the corresponding subject number.

[0052] As described above, the bonding tool 120 picks up and holds the semiconductor chips 310 (first semiconductor chip 310a, second semiconductor chip 310b) prepared by the chip supply device 500 by attracting them with the collet 122. At this time, the bonding tool 120 attempts to attract the center of the semiconductor chip 310 in a preset orientation, but in reality, it may attract them with some displacement. Therefore, the bonding control unit 214 checks the actual position and orientation in which the semiconductor chip 310 is held and recognizes a reference position for placing the semiconductor chip 310 on the lead frame 330.

[0053] The upward-view image shown in Figure 7 is an image captured by the third imaging unit 150 looking up at the first semiconductor chip 310a, so the collet 122 that holds the first semiconductor chip 310a is also captured. Therefore, the bonding control unit 214 calculates the image coordinates of the collet center 123 by detecting the circle which is the outline of the collet 122.

[0054] Furthermore, in this embodiment, the first semiconductor chip 310a has a chip reference mark 311a on the surface intended to contact the lead frame 330, and the bonding control unit 214 calculates the image coordinates of the chip reference mark 311a that are captured in the upward-view image. From the image coordinates of the collet center 123 and the image coordinates of the chip reference mark 311a calculated in this way, the bonding control unit 214 can recognize the actual position and orientation in which the first semiconductor chip 310a is held relative to the collet 122. For example, if the position where the chip reference mark 311a is provided is the reference position for placing the first semiconductor chip 310a in the intended mounting area of ​​the lead frame 330, the bonding control unit 214 can calculate the three-dimensional coordinates of the reference position of the first semiconductor chip 310a at the time the upward-view image was captured. Therefore, even if the bonding tool 120 or the head unit 110 is moved afterward, the three-dimensional coordinates of the reference position can be tracked as long as the collet 122 continues to hold the first semiconductor chip 310a.

[0055] Once the bonding control unit 214 recognizes the three-dimensional coordinates of the reference position, it drives the tool drive motor 121 to raise the bonding tool 120 to a position where the held first semiconductor chip 310a is out of the field of view of the overhead imaging unit. Then, by driving the head drive motor 111, it moves the head unit 110 so that the bonding tool 120 is directly above the die pad, which is the planned mounting area for the first semiconductor chip 310a, and so that the focal plane 110a of the overhead imaging unit coincides with the first area surface 330a. Note that the raising of the bonding tool 120 and the movement of the head unit 110 may be performed in parallel.

[0056] Figure 8 shows the first imaging unit 130 and the second imaging unit 140 imaging the planned mounting area on the lead frame 330 with the head unit 110 and bonding tool 120 positioned as shown. Figure 9 is a partial perspective view of Figure 8. In this embodiment, the lead frame 330 has one die pad 320 in each of the unit regions 322 that will be cut out and housed in a single package in the future. The die pad 320 shown is the planned mounting area on which the first semiconductor chip 310a will be mounted. Each unit region 322 is also provided with a pad reference mark 321 indicating its reference position.

[0057] In the configuration shown in Figures 8 and 9, the first imaging unit 130 and the second imaging unit 140 can capture the die pad 320 and the pad reference mark 321, both contained within the same unit region 322, within their field of view and acquire images in focus. The bonding control unit 214 uses the first overhead image output by the first imaging unit 130 and the second overhead image output by the second imaging unit 140 to calculate the coordinates of the target position to which the reference position of the first semiconductor chip 310a should be aligned when it is placed on the die pad 320.

[0058] Figure 10 shows the procedure for calculating the target coordinates on which the first semiconductor chip 310a will be placed from the first overhead image and the second overhead image. The first imaging unit 130 images the die pad 320 from the pad reference mark 321 side, so the output image, the first overhead image, shows the unit region 322 as a trapezoidal shape that extends toward the pad reference mark 321 side. Conversely, the second imaging unit 140 images the die pad 320 from the opposite side of the pad reference mark 321, so the output image, the second overhead image, shows the unit region 322 as a trapezoidal shape that narrows toward the pad reference mark 321 side.

[0059] The bonding control unit 214 determines the image coordinates (x) of the pad reference mark 321 from the first overhead image. 1k ,y 1k) is determined, and the image coordinates (x) of the pad reference mark 321 are also determined from the second overhead image. 2k ,y 2k ) is determined. Then, for example, by referring to a conversion table that converts image coordinates to three-dimensional coordinates, the index coordinates (X) which are the three-dimensional coordinates of the pad reference mark 321 are determined from these image coordinates. k ,Y k ,Z k The coordinate values ​​of this index coordinate are a provisional target position for calculating the precise target position, and as mentioned above, they contain errors due to the influence of temperature changes in the surrounding environment. Therefore, the calibration values ​​(ΔX, ΔY) are read from the calibration data 221 and corrected. The corrected index coordinate (X) obtained in this way is calculated. k +ΔX,Y k +ΔY,Z k The coordinate values ​​of ) can be expected to be error-free compared to the spatial coordinates calculated from the upward-view image.

[0060] Since the target position of the die pad 320 and the relative position of the pad reference mark 321 are known, the bonding control unit 214 adjusts the corrected index coordinates (X k +ΔX,Y k +ΔY,Z k ) to the coordinates of the target position (X Ta ,Y Ta ,Z Ta It can accurately calculate ).

[0061] Once the coordinates of the target position are determined, the first semiconductor chip 310a is placed on the target position and bonded. Figure 11 shows the bonding tool 120 placing the first semiconductor chip 310a on the target position and bonding it.

[0062] As described above, the bonding control unit 214 tracks and understands the three-dimensional coordinates of the reference position of the first semiconductor chip 310a in relation to the movement of the bonding tool 120 and the head unit 110, and moves the first semiconductor chip 310a so that this reference position matches the target position on the die pad 320. Specifically, the head drive motor 111 is driven via the drive control unit 212 to finely adjust the position of the head unit 110 in the XY direction, and the amount of rotation of the bonding tool 120 around the Z axis is finely adjusted by driving the tool drive motor 121. Then, with the X and Y coordinates of the reference position and the X and Y coordinates of the target position matching, the bonding tool 120 is lowered and the first semiconductor chip 310a is placed on the die pad 320. After that, the first semiconductor chip 310a is pressed with the tip of the collet 122 and heated with the heater 124 to bond it to the die pad 320.

[0063] In this embodiment, as described above, the position of the head unit 110 in the Z direction when the calibration value is calculated is the same as the position of the head unit 110 in the Z direction when the overhead imaging unit images the chip reference mark 311a. Furthermore, as explained using Figures 6 and 7, the three-dimensional coordinates of the chip reference mark 311a are calculated by aligning the height of the contact surface of the first semiconductor chip 310a held by the collet 122 with the height of the index surface 173a on which the calibration process was performed. The first region surface 330a is then made to match the height of the index surface 173a on which the calibration process was performed. In other words, the position of the head unit 110 in the Z direction is the same when the calibration value is obtained, when the three-dimensional coordinates of the chip reference mark 311a are calculated, and when the first semiconductor chip 310a is placed on the die pad 320.

[0064] Therefore, there is no need to consider the error in the XY direction between the actual three-dimensional coordinates and the recognized three-dimensional coordinates that may occur when the head unit 110 or bonding tool 120 is moved in the Z direction. For example, in the state shown in Figure 8, the bonding tool 120 holds the first semiconductor chip 310a and is retracted from the field of view of the overhead imaging unit. However, the actual X and Y coordinates of the reference position in this state may not match the X and Y coordinates recognized by the bonding control unit 214 due to the influence of play between elements of the movement mechanism that moves the bonding tool 120 up and down. However, as shown in Figure 11, when the first semiconductor chip 310a is placed on the first region surface 330a, the height of the bonding tool 120 is the same as the height of the bonding tool 120 when the three-dimensional coordinates of the chip reference mark 311a are calculated, and the error factor caused by the movement mechanism is eliminated. In other words, when the first semiconductor chip 310a is placed on the first region surface 330a, the actual X and Y coordinates of the reference position will coincide with the X and Y coordinates recognized by the bonding control unit 214. Therefore, in this embodiment, when the first semiconductor chip 310a is placed and bonded to the die pad 320, the height of the first region surface 330a is made to match the height of the indicator surface 173a.

[0065] Figure 12 shows the bonding tool 120 being retracted. Once bonding of the semi-first semiconductor chip 310a is complete, as shown in the figure, the bonding control unit 214 raises the bonding tool 120 by driving the tool drive motor 121 via the drive control unit 212.

[0066] The bonding control unit 214 then starts the process of stacking the second semiconductor chip 310b onto the first semiconductor chip 310a, which has already been bonded, and bonding them. Similar to the acquisition of the first semiconductor chip 310a as explained with reference to Figure 5, the bonding control unit 214 inverts one of the semiconductor chips 310 placed on the chip supply device 500 that is to be bonded, using the pickup mechanism 510 and the inversion mechanism 520, and then picks it up by attracting it with the collet 122.

[0067] Figure 13 shows the third imaging unit 150 imaging the second semiconductor chip 310b which is adsorbed onto the bonding tool 120, and adjusting the height of the second region surface 330b, which is the region surface of the area where the second semiconductor chip 310b is to be placed, to the height of the indicator surface 173a.

[0068] The bonding control unit 214 drives the head drive motor 111 via the drive control unit 212 to move the head unit 110 so that the focal plane 110a of the overhead imaging unit is at the same height as the indicator surface 173a, and the third imaging unit 150 is positioned directly below the bonding tool 120. Then, by driving the tool drive motor 121, the bonding tool 120 is lowered so that the contact surface of the second semiconductor chip 310b that is to be laminated is at the same height as the indicator surface 173a. This contact surface includes the mounting surface of the second semiconductor chip 310b. Once this arrangement adjustment is complete, the bonding control unit 214 causes the third imaging unit 150 to image the contact surface of the second semiconductor chip 310b held by the bonding tool 120 via the image acquisition unit 211. The contact surface of the second semiconductor chip 310b is the surface opposite to the surface that is attracted to the collet 122, and is the surface that faces the third imaging unit 150.

[0069] The bonding control unit 214 adjusts the position of the stage 190 by driving the stage drive motor 191 via the drive control unit 212 before and after the process of causing the third imaging unit 150 to image the contact surface of the second semiconductor chip 310b. Specifically, it adjusts the stage so that the second region surface 330b, which is the region surface of the area where the second semiconductor chip 310b is to be placed, is at the same height as the index surface 173a. For example, since the thicknesses of the lead frame 330 and the first semiconductor chip 310a are known, the bonding control unit 214 only needs to move the stage surface 190a to Z=Z2, which is the height of the index surface 173a minus the thickness of the lead frame 330 and the thickness of the first semiconductor chip 310a.

[0070] Furthermore, if the second region surface 330b has already been adjusted to the same height as the indicator surface 173a, the bonding control unit 214 will skip the position adjustment of the stage 190. Also, the position adjustment of the stage 190 only needs to be performed before the bonding control unit 214 begins the process of placing the second semiconductor chip 310b in the planned mounting region.

[0071] Figure 14 schematically shows an upward-view image output by the third imaging unit 150 after imaging the second semiconductor chip 310b held by the bonding tool 120. The bonding control unit 214, as with the first semiconductor chip 310a, confirms the adsorption position and orientation of the second semiconductor chip 310b relative to the collet 122 and recognizes a reference position for placing the second semiconductor chip 310b onto the first semiconductor chip 310a.

[0072] The bonding control unit 214 calculates the image coordinates of the collet center 123 by detecting the circle that is the contour of the collet 122. In this embodiment, the second semiconductor chip 310b has a chip reference mark 311b on the surface that is intended to contact the first semiconductor chip 310a, and the bonding control unit 214 calculates the image coordinates of the chip reference mark 311b that is visible in the upward view image. From the image coordinates of the collet center 123 and the image coordinates of the chip reference mark 311b calculated in this way, the bonding control unit 214 can recognize the actual position and orientation in which the second semiconductor chip 310b is held relative to the collet 122. Therefore, even if the bonding tool 120 or the head unit 110 is moved afterward, the three-dimensional coordinates of the reference position can be tracked as long as the collet 122 continues to hold the second semiconductor chip 310b.

[0073] Once the bonding control unit 214 recognizes the three-dimensional coordinates of the reference position, it drives the tool drive motor 121 to raise the bonding tool 120 to a position where the second semiconductor chip 310b being held is out of the field of view of the overhead imaging unit. Then, by driving the head drive motor 111, it moves the head unit 110 so that the bonding tool 120 is directly above the first semiconductor chip 310a, which is the area where the second semiconductor chip 310b is to be placed, and so that the focal plane 110a of the overhead imaging unit coincides with the second area plane 330b. Note that the raising of the bonding tool 120 and the movement of the head unit 110 may be performed in parallel.

[0074] Figure 15 shows the first imaging unit 130 and the second imaging unit 140 imaging the area to be mounted on the first semiconductor chip 310a with the head unit 110 and the bonding tool 120 positioned as shown. In this state, the first imaging unit 130 and the second imaging unit 140 can each capture the area to be mounted on the target first semiconductor chip 310a within their field of view and image it in focus. The bonding control unit 214 uses the first overhead image output by the first imaging unit 130 and the second overhead image output by the second imaging unit 140 to calculate the coordinates of the target position to which the reference position of the second semiconductor chip 310b should be aligned when it is mounted on the first semiconductor chip 310a.

[0075] Figure 16 shows the procedure for calculating the target coordinates for mounting the second semiconductor chip 310b from the first and second overhead views. As shown in the figure, the first semiconductor chip 310a to be stacked has already been bonded within the unit region 322 on the lead frame 330, and both the first and second overhead views show the stacking reference mark 323 indicating the reference position on the upper surface of the first semiconductor chip 310a.

[0076] The bonding control unit 214 determines the image coordinates (x) of the stacking reference mark 323 from the first overhead image. 1j ,y 1j) is determined, and the image coordinates (x) of the stacking reference mark 323 are also determined from the second overhead image. 2j ,y 2j ) is determined. Then, from these image coordinates, the index coordinates (X) are the three-dimensional coordinates of the pad reference mark 321. j ,Y j ,Z j The coordinate values ​​of this index coordinate are a provisional target position for calculating the precise target position, and as mentioned above, they contain errors due to the influence of temperature changes in the surrounding environment. Therefore, the calibration values ​​(ΔX, ΔY) are read from the calibration data 221 and corrected. The corrected index coordinate (X) obtained in this way is calculated. j +ΔX,Y j +ΔY,Z j The coordinate values ​​of ) can be expected to be error-free with respect to the spatial coordinates calculated from the upward view image. Since the relative positions of the target position on the first semiconductor chip 310a and the stacking reference mark 323 are known, the bonding control unit 214 calculates the corrected index coordinates (X j +ΔX,Y j +ΔY,Z j ) to the coordinates of the target position (X Tb ,Y Tb ,Z Tb It can accurately calculate ).

[0077] Once the coordinates of the target position are determined, the second semiconductor chip 310b is placed at the target position and bonded. Figure 17 shows how the bonding tool 120 places the second semiconductor chip 310b at the target position on the first semiconductor chip 310a and performs the bonding.

[0078] As described above, the bonding control unit 214 tracks and understands the three-dimensional coordinates of the reference position of the second semiconductor chip 310b in relation to the movement of the bonding tool 120 and the head unit 110, and moves the second semiconductor chip 310b so that this reference position matches the target position of the first semiconductor chip 310a. Specifically, the head drive motor 111 is driven via the drive control unit 212 to finely adjust the position of the head unit 110 in the XY direction, and the amount of rotation of the bonding tool 120 around the Z axis is finely adjusted by driving the tool drive motor 121. Then, with the X and Y coordinates of the reference position and the X and Y coordinates of the target position matching, the bonding tool 120 is lowered and the second semiconductor chip 310b is placed on the first semiconductor chip 310a. After that, the second semiconductor chip 310b is pressed with the tip of the collet 122 and heated with the heater 124 to bond it to the first semiconductor chip 310a.

[0079] In this embodiment, as described above, the position of the head unit 110 in the Z direction when the calibration value is calculated is the same as the position of the head unit 110 in the Z direction when the overhead imaging unit images the chip reference mark 311b. Furthermore, as explained using Figures 13 and 14, the three-dimensional coordinates of the chip reference mark 311b are calculated by aligning the height of the contact surface of the second semiconductor chip 310b held by the collet 122 with the height of the index surface 173a on which the calibration process was performed. The second region surface 330b is then made to match the height of the index surface 173a on which the calibration process was performed. In other words, the position of the head unit 110 in the Z direction is the same when the calibration value is obtained, when the three-dimensional coordinates of the chip reference mark 311b are calculated, and when the second semiconductor chip 310b is placed on the first semiconductor chip 310a.

[0080] Therefore, there is no need to consider the error in the XY direction between the actual three-dimensional coordinates and the recognized three-dimensional coordinates that may occur when the head unit 110 or bonding tool 120 is moved in the Z direction. For example, in the state shown in Figure 15, the bonding tool 120 holds the second semiconductor chip 310b and is retracted from the field of view of the overhead imaging unit. However, the actual X and Y coordinates of the reference position in this state may not match the X and Y coordinates recognized by the bonding control unit 214 due to the influence of play between elements of the movement mechanism that moves the bonding tool 120 up and down. However, as shown in Figure 17, when the second semiconductor chip 310b is placed on the second region surface 330b, the height of the bonding tool 120 is the same as the height of the bonding tool 120 when the three-dimensional coordinates of the chip reference mark 311b are calculated, and the error factor caused by the movement mechanism is eliminated. In other words, when the second semiconductor chip 310b is placed on the second region surface 330b, the actual X and Y coordinates of the reference position will coincide with the X and Y coordinates recognized by the bonding control unit 214. Therefore, in this embodiment, when the second semiconductor chip 310b is placed and bonded to the first semiconductor chip 310a, the height of the second region surface 330b is made to match the height of the indicator surface 173a.

[0081] Once bonding of the second semiconductor chip 310b is complete, the bonding control unit 214 drives the tool drive motor 121 via the drive control unit 212 to raise the bonding tool 120. When bonding a new semiconductor chip 310, the process is repeated by returning to the state shown in Figure 5. In this embodiment, after bonding the first semiconductor chip 310a to the die pad 320, the position of the stage 190 is adjusted and the second semiconductor chip 310b is stacked on the first semiconductor chip 310a. However, the processing steps are not limited to this. For example, the first semiconductor chips 310a may be mounted one after another on each of the multiple die pads 320 provided on the lead frame 330, and then the position of the stage 190 may be adjusted to sequentially mount the second semiconductor chips 310b on each of these first semiconductor chips 310a. By adopting such a process, the number of times the position of the stage 190 is adjusted can be reduced, and thus a reduction in lead time can be expected.

[0082] Next, the entire bonding procedure, including the calibration and bonding processes described above, is summarized in a flowchart. Figure 18 is a flowchart illustrating the bonding procedure for semiconductor chip 310.

[0083] In step S11, the calibration control unit 213 starts a calibration control step to perform the calibration process. Further details will be explained later in a subflow diagram. Note that if bonding is to be started from an initial state where the coordinates between imaging units are correctly adjusted, the first calibration control step may be skipped.

[0084] Once the calibration control unit 213 has finished executing the calibration control step, the process proceeds to step S12, where the bonding control unit 214 starts the bonding control step to perform the bonding process. Further details will be explained later in the subflow diagram.

[0085] Once the bonding control unit 214 has finished executing the bonding control step, the process proceeds to step S13, where the calibration control unit 213 determines whether the state of the bonding apparatus 100 at that point satisfies the preset calibration timing conditions. The preset calibration timing conditions are those that may necessitate further calibration. For example, as mentioned above, the number of lots processed, the working time for the bonding operation, and the temperature detected by the temperature detection unit are candidates for setting conditions.

[0086] If the calibration control unit 213 determines that the conditions are met in step S13, it returns to step S11. If it determines that the conditions are not met, it proceeds to step S14. If it proceeds to step S14, the bonding control unit 214 determines whether all scheduled bonding processes have been completed. If it determines that there are still semiconductor chips 310 to be bonded, it returns to step S12, and if it determines that all bonding processes have been completed, it terminates the series of processes.

[0087] Figure 19 is a subflow diagram illustrating the procedure of the calibration control step. The calibration control step mainly performs the processes described using Figure 4. In step S1101, the calibration control unit 213 moves the index plate 172 to place the calibration index 173 into the center of the field of view of the third imaging unit 150. Subsequently, in step S1102, the calibration control unit 213 moves the head unit 110 so that the index surface 173a of the calibration index 173 is flush with the focal planes 110a of the first imaging unit 130 and the second imaging unit 140, and so that the calibration index 173 is positioned directly below the bonding tool 120.

[0088] The calibration control unit 213 proceeds to step S1103, instructing each imaging unit to perform imaging via the image acquisition unit 211, and acquiring a first overhead image from the first imaging unit 130, a second overhead image from the second imaging unit 140, and an upward-looking image from the third imaging unit 150. Then, in the following step S1104, the three-dimensional coordinates of the calibration index 173 are calculated based on the image coordinates of the calibration index 173 images captured in the first overhead image and the second overhead image, respectively, and the three-dimensional coordinates of the calibration index 173 are calculated based on the image of the calibration index 173 captured in the upward-looking image. The calibration control unit 213 calculates the difference in the XY plane direction of each of the three-dimensional coordinates calculated in this way as the calibration value. The calculated calibration value is stored in the storage unit 220 as calibration data 221.

[0089] Subsequently, in step S1105, the calibration control unit 213 moves the indicator plate 172 to move the calibration index 173 out of the field of view of the third imaging unit 150. Once the retraction of the calibration index 173 is complete, the process returns to the main flow. Note that the retraction of the calibration index 173 may also be performed during the subsequent bonding process.

[0090] Figure 20 is a subflow diagram illustrating the procedure of the bonding control step. The bonding control step mainly executes the processes described using Figures 5 to 17. In step S1201, the bonding control unit 214 assigns "1" to counter n.

[0091] The process proceeds to step S1202, where the head unit 110 is moved to the top of the chip supply device 500, and the bonding tool 120 is lowered. Then, the nth semiconductor chip to be placed as the nth layer from among the semiconductor chips 310 placed on the chip supply device 500 is inverted by the pickup mechanism 510 and the inversion mechanism 520, and picked up by the collet 122. For example, if n=1, the first semiconductor chip 310a is picked up. Once the nth semiconductor chip has been picked up, the bonding tool 120 is raised.

[0092] In step S1203, the bonding control unit 214 moves the head unit 110 so that the index surface 173a and the focal planes 110a of the first imaging unit 130 and the second imaging unit 140 are on the same plane, and the third imaging unit 150 is positioned directly below the bonding tool 120. Furthermore, in step S1204, the bonding tool 120 is lowered so that the surface of the nth semiconductor chip being held that is intended to contact the stacking target is on the same plane as the index surface 173a.

[0093] Once the arrangement adjustments are complete, the bonding control unit 214, in step S1205, causes the third imaging unit 150 to image the contact surface of the nth semiconductor chip held by the bonding tool 120. Then, in step S1206, it acquires the upward-view image output by the third imaging unit 150 and recognizes the three-dimensional coordinates of the reference position of the nth semiconductor chip based on the image coordinates of the chip reference marks captured in the image.

[0094] In step S1207, the bonding control unit 214 adjusts the position of the stage 190 so that the nth region surface is flush with the index surface 173a. For example, if n=1, the stage surface 190a is moved to Z=Z1 so that the first region surface 330a is flush with the index surface 173a.

[0095] In step S1208, the bonding control unit 214 raises the bonding tool 120 to a position where the nth semiconductor chip being held is out of the field of view of the overhead imaging unit, and moves the head unit 110 so that the bonding tool 120 is directly above the area where the nth semiconductor chip is to be placed. In the following step S1209, the height of the head unit 110 is adjusted so that the focal plane 110a of the overhead imaging unit coincides with the nth region plane.

[0096] Once the adjustment of the arrangement is complete, the bonding control unit 214, in step S1210, causes the first imaging unit 130 and the second imaging unit 140 to image the area near the planned placement area, including reference marks such as the pad reference mark 321 and the stacking reference mark 323. Then, it acquires the first overhead image output by the first imaging unit 130 and the second overhead image output by the second imaging unit 140, and in step S1211, calculates the three-dimensional coordinates of the target position based on the image coordinates and calibration values ​​of the reference marks that are captured in the image.

[0097] Once the target position is determined, the process proceeds to step S1212, where the bonding control unit 214 moves the head unit 110 and the bonding tool 120 so that the reference position of the nth semiconductor chip matches the target position, and places the nth semiconductor chip in the planned mounting area. Subsequently, the nth semiconductor chip is pressurized / heated to complete the bonding. Once the bonding of the nth semiconductor chip is complete, the bonding tool 120 is raised.

[0098] The bonding control unit 214 proceeds to step S1213 and increments the counter n. Then, in step S1214, it checks whether the incremented counter n exceeds the planned total number of layers n0. In the above-described embodiment, the first semiconductor chip 310a, which will be the first layer, is bonded onto the lead frame 330, and the second semiconductor chip 310b, which will be the second layer, is bonded on top of it, so the planned total number of layers is "2". If the counter n does not exceed the planned total number of layers n0, the process returns to step S1202 and performs bonding of the nth semiconductor chip corresponding to the incremented n. If the counter n exceeds the planned total number of layers n0, the process returns to the main flow.

[0099] In the embodiment described above, the calibration process and the bonding process are separated, and the calibration process is executed when the state of the bonding apparatus 100 satisfies the conditions of a preset calibration timing. Therefore, once the calibration process is executed, the calculated calibration value is stored in the storage unit 220, and in the bonding process performed until the next calibration process is executed, the calibration value is referenced each time. However, the calibration process may be incorporated into a series of bonding processes, and the calibration value may be updated each time during the bonding process of each nth semiconductor chip. Other such embodiments will be described below. In the other embodiments described below, the configuration of the bonding apparatus itself is the same as in the embodiment described above, so its explanation will be omitted, and mainly the differences in the processing procedures will be described.

[0100] Figure 21 shows how three imaging units capture the calibration index 173 in another embodiment. In this embodiment, a calibration process is performed to calculate the calibration value between the acquisition process of the nth semiconductor chip and the imaging process of the nth semiconductor chip by the third imaging unit 150.

[0101] Figure 22 more specifically shows the collet 122 holding the first semiconductor chip 310a to be bonded, while these components are moved out of the field of view of the overhead imaging unit. The first semiconductor chip 310a held by the collet 122 will then be placed on the planned mounting area on the lead frame 330 and bonded, as indicated by the dotted line. In the figure, the position of the stage 190 is adjusted so that the first area surface 330a is at the same height as the index surface 173a, but the position adjustment of the stage 190 only needs to be performed before the bonding control unit 214 begins the process of placing the first semiconductor chip 310a on the planned mounting area.

[0102] The rest of the setup is similar to that shown in Figure 4, where the three imaging units capture the calibration index 173. Specifically, the position of the head unit 110 is adjusted so that the focal plane 110a of the overhead imaging unit and the index plane 173a are at the same height. The calibration index 173 is positioned near the center of the field of view of each imaging unit.

[0103] The calibration control unit 213 calculates calibration values ​​as described above based on the first overhead image, second overhead image, and upward view image obtained by each imaging unit. Once the calibration control unit 213 has calculated the calibration values, the bonding control unit 214 then lowers the bonding tool 120 and performs the subsequent processing of the first semiconductor chip 310a by the third imaging unit 150, as explained with reference to Figure 6. In this way, the calibration values ​​calculated in the calibration process executed in synchronization with the bonding process are used only for the alignment of the first semiconductor chip 310a to be bonded in that bonding process.

[0104] The same procedure applies when bonding the second semiconductor chip 310b. Between the acquisition of the second semiconductor chip 310b and the imaging of the second semiconductor chip 310b by the third imaging unit 150, a calibration process is performed to calculate a calibration value. The calibration control unit 213 calculates the calibration value based on the first overhead image, second overhead image, and upward view image obtained by each imaging unit. Subsequently, it lowers the bonding tool 120 and performs the subsequent processing of the second semiconductor chip 310b by the third imaging unit 150, as explained using Figure 13. In this way, the calibration value calculated in the calibration process performed in synchronization with the bonding process is used only for the alignment of the second semiconductor chip 310b to be bonded in that bonding process.

[0105] In this way, if the calibration control unit 213 images the calibration index and updates the calibration value in synchronization with the bonding control unit 214's process of causing the third imaging unit 150 to image the nth semiconductor chip, the time interval between the time the calibration value is calculated and the time when the calibration value is used can be shortened. Therefore, it is expected that more accurate alignment can be achieved in response to temperature changes in the surrounding environment.

[0106] Figure 22 is a flowchart illustrating the semiconductor chip bonding procedure in this other embodiment. For processing procedures that are the same as those described using Figures 18 to 20, the same step numbers are used, and the specific details of the processing content are omitted. As mentioned above, this embodiment is a processing procedure that incorporates calibration processing into each bonding process, so the flow of the process will be explained mainly.

[0107] In step S1201, the bonding control unit 214 substitutes "1" for counter n. In step S1202, the nth semiconductor chip to be placed as the nth layer is picked up by the collet 122 from among the semiconductor chips 310 placed on the chip supply device 500. Before or after step S1202, or in parallel with step S1202, the calibration control unit 213 performs step S1101, which involves moving the index plate 172 to place the calibration index 173 into the center of the field of view of the third imaging unit 150.

[0108] Next, the process proceeds to step S1203, in which the calibration control unit 213 moves the head unit 110 so that the index surface 173a and the focal plane 110a are on the same plane, and the calibration index 173 is positioned directly below the bonding tool 120.

[0109] In the following step S1103, the calibration control unit 213 causes the first imaging unit 130, the second imaging unit 140, and the third imaging unit 150 to perform imaging, and then in step S1104, it calculates calibration values. After calculating the calibration values, the process proceeds to step S1105, where the calibration index 173 is moved out of the field of view of each imaging unit. Once the calibration control unit 213 has moved the calibration index 173 out of the field of view, steps S1204 to S1212 are the same as the processing procedure described using Figure 20.

[0110] When the bonding control unit 214 proceeds from step S1212 to step S1213, it increments the counter n. Then, in step S1214, it checks whether the incremented counter n exceeds the planned total number of stacks n0. If the counter n does not exceed the planned total number of stacks n0, it returns to step S1202 and performs bonding of the nth semiconductor chip corresponding to the incremented n. If the counter n exceeds the planned total number of stacks n0, it proceeds to step S14.

[0111] When the bonding control unit 214 proceeds to step S14, it determines whether all scheduled bonding processes have been completed. If it determines that there are still semiconductor chips to be bonded, it returns to step S1201. If it determines that all bonding processes have been completed, it terminates the series of processes.

[0112] In the embodiment described above, including other embodiments, the bonding control unit 214 adjusts the position of the stage 190 so that the area surface of the planned mounting area (for example, the first area surface 330a) and the indicator surface 173a are at the same height. However, if the position of the stage 190 is adjusted based on the stage surface 190a, the height of the planned mounting area may not match the height of the indicator surface 173a due to variations in the thickness of the lead frame 330 and the first semiconductor chip 310a, as well as the influence of the adhesive. Therefore, a modified example that addresses this problem will be described.

[0113] The modified version adds an additional step between steps S1210 and S1211 of the bonding control step described using Figure 20. Figure 23 is a flowchart illustrating the additional step related to the modified version.

[0114] In step S1210, the bonding control unit 214 has the first imaging unit 130 and the second imaging unit 140 image the area near the planned mounting area to acquire two overhead images and calculate the provisional three-dimensional coordinates of the target position. From the Z coordinate value of the provisional three-dimensional coordinates calculated here, the bonding control unit 214 can recognize the height of the area surface of the planned mounting area. Then, proceeding to step S2301, it determines whether the height of the area surface falls within a preset tolerance range relative to the height of the index surface 173a measured in the calibration control step. If it does not, proceeding to step S2302, the stage drive motor 191 is driven via the drive control unit 212 based on the recognized height of the area surface to readjust the position of the stage 190.

[0115] After readjusting the position of the stage 190, the bonding control unit 214, in step S2303, has the first imaging unit 130 and the second imaging unit 140 image the area near the planned placement area again to obtain two overhead images, and calculates the provisional three-dimensional coordinates of the target position in the same way as in step S1210. After calculating the provisional three-dimensional coordinates, it returns to step S2301.

[0116] If it is determined in step S2301 that the height of the area surface is within a preset tolerance range, the process proceeds to step S1211. Adding such an additional step between steps S1210 and S1211 allows for a more accurate calculation of the three-dimensional coordinates of the target position.

[0117] In the embodiment described above, the overhead imaging unit was configured to include two imaging units, a first imaging unit 130 and a second imaging unit 140. However, the overhead imaging unit may be configured to include three or more imaging units, each employing a shine-proof optical system. Furthermore, in the embodiment described above, the three-dimensional coordinates of the object were calculated using the parallax between the first and second overhead images. However, the method for calculating three-dimensional coordinates using the overhead imaging unit is not limited to this. For example, one overhead imaging unit employing a shine-proof optical system may be used, and other auxiliary means may be employed. For example, the head unit 110 may be provided with a light projection unit capable of pattern projection, and the shape of the light projection pattern observed on the observation surface may be analyzed using the overhead image output by the overhead imaging unit to calculate the three-dimensional coordinates of the object. In addition, although a flip-chip bonder was described in this embodiment, it is not limited to this and can be applied to die bonders, surface mount machines for mounting electronic components on substrates, and other mounting devices. [Explanation of symbols]

[0118] 100...Bonding device, 110...Head unit, 110a...Focal plane, 111...Head drive motor, 120...Bonding tool, 121...Tool drive motor, 122...Collet, 123...Collet center, 124...Heater, 130...First imaging unit, 131...First optical system, 131a...Object-side lens group, 131b...Image-side lens group, 132...First image sensor, 133...Aperture, 140...Second imaging unit, 141...Second optical system, 142...Second image sensor, 150...Third imaging unit, 150a...Focal plane, 151...Third optical system, 152...Third image sensor, 170...Calibration unit, 171...Index drive motor, 172...Index plate, 173...Calibration index, 173a...Index surface, 1 90…Stage, 190a…Stage surface, 191…Stage drive motor, 210…Calculation processing unit, 211…Image acquisition unit, 212…Drive control unit, 213…Calibration control unit, 214…Bonding control unit, 220…Storage unit, 221…Calibration data, 230…Input / output device, 310…Semiconductor chip, 310a…First semiconductor chip, 310b…Second semiconductor chip, 311a…Chip reference mark, 311b…Chip reference mark, 320…Die pad, 321…Pad reference mark, 322…Unit area, 323…Stacking reference mark, 330…Lead frame, 330a…First area surface, 330b…Second area surface, 500…Chip supply device, 510…Pickup mechanism, 520…Inversion mechanism

Claims

1. A mounting tool that picks up and holds a mounting object having a mounting surface, and mounts the mounting surface to a mounting area set for a substrate placed on a stage or for other mounting objects already mounted on the substrate, An overhead imaging unit for imaging the aforementioned planned placement area from the same side as the mounting tool with respect to the stage surface, wherein the optical system and image sensor are arranged to satisfy the Scheinproof condition such that the focal plane is a plane parallel to the stage surface of the aforementioned stage, An upward-viewing imaging unit for imaging the mounted object, which is held in the mounting tool, by viewing it from the side opposite to the overhead-viewing imaging unit relative to the stage surface, Calibration indicators arranged to be image-captured by the overhead imaging unit and the upward imaging unit, The mounting control unit adjusts the position of the mounting tool so that the mounting surface is at the same height as the indicator surface of the calibration index, captures the mounting surface with the upward viewing imaging unit, recognizes the reference position of the mounted object based on the upward viewing image output, adjusts the position of the stage so that the mounting surface of the previously described placement area is at the same height as the indicator surface, and mounts the object onto the mounting surface based on the reference position. An implementation device equipped with the following features.

2. The system includes a calibration control unit that calculates a calibration value for calibrating the difference between coordinate values ​​calculated based on the overhead image output by the overhead imaging unit and coordinate values ​​calculated based on the upward image output by the upward imaging unit, based on the overhead image output by the overhead imaging unit and the upward image output by the upward imaging unit, wherein the calibration index is captured by the overhead imaging unit and output. The mounting apparatus according to claim 1, wherein the mounting control unit adjusts the position of the overhead imaging unit so that the focal plane is at the same height as the mounting surface, and the overhead imaging unit captures the overhead image of the area to be mounted, recognizes the target position of the area to be mounted based on the overhead image and the calibration value, and places the mounting body in the area to be mounted so that the reference position matches the target position.

3. The mounting apparatus according to claim 2, wherein the calibration control unit calculates and updates the calibration value each time the mounting control unit completes mounting of a predetermined lot of the mounting bodies.

4. The mounting apparatus according to claim 2, wherein the calibration control unit calculates and updates the calibration value based on the working time of the mounting work performed by the mounting control unit.

5. It includes a temperature detection unit for detecting the temperature of the overhead imaging unit, The mounting device according to claim 2, wherein the calibration control unit calculates and updates the calibration value when the temperature detection unit detects a preset temperature.

6. The mounting apparatus according to claim 2, wherein the calibration control unit synchronizes with the process by which the mounting control unit causes the mounting surface of the mounting body to be imaged by the upward-viewing imaging unit, causing the overhead-viewing imaging unit and the upward-viewing imaging unit to image the calibration index, and calculates the calibration value.

7. The mounting apparatus according to claim 2, wherein the mounting control unit adjusts the position of the stage after sequentially mounting a plurality of mounting bodies onto the substrate, and then sequentially mounts other mounting bodies onto each of the mounting bodies mounted on the substrate.

8. The mounting apparatus according to claim 2, wherein the mounting control unit measures the height of the surface to be mounted when it adjusts the position of the overhead imaging unit so that the focal plane is at the same height as the surface to be mounted, and if the measured height of the surface to be mounted does not fall within a preset tolerance range based on the indicator plane, it readjusts the position of the stage and then mounts the mounted object.

9. The overhead imaging unit includes a first imaging unit and a second imaging unit, which are adjusted so that their respective focal planes coincide. The mounting control unit recognizes the target position by correcting the provisional target position calculated based on a first overhead image obtained by having the first imaging unit image the previously described planned mounting area and outputting it, and a second overhead image obtained by having the second imaging unit image the previously described planned mounting area and outputting it, using the calibration value.

10. A mounting method for a mounting object using a mounting apparatus comprising: a mounting tool for picking up and holding a mounting object having a mounting surface, and mounting the mounting surface to a mounting area set for a substrate placed on a stage or another mounting object already mounted on the substrate; an overhead imaging unit for imaging the aforementioned mounting area from the same side as the mounting tool with respect to the stage surface, with an optical system and an image sensor arranged to satisfy shineproof conditions such that the plane parallel to the stage surface of the stage becomes the focal plane; an upward imaging unit for imaging the mounting object held by the mounting tool from the opposite side of the overhead imaging unit with respect to the stage surface; and a calibration index arranged to be imageable by the overhead imaging unit and the upward imaging unit, wherein A mounting method comprising a mounting control step of adjusting the position of the mounting tool so that the mounting surface is at the same height as the indicator surface of the calibration index, having the upward-viewing imaging unit capture an image of the mounting surface and recognizing the reference position of the mounted object based on the output upward-view image, adjusting the position of the stage so that the mounting surface of the planned mounting area is at the same height as the indicator surface, and mounting the object onto the mounting surface based on the reference position.

11. A mounting control program for controlling a mounting apparatus comprising: a mounting tool for picking up and holding a mounting object having a mounting surface, and mounting the mounting surface to a mounting area set for a substrate placed on a stage or another mounting object already mounted on the substrate; an overhead imaging unit for imaging the aforementioned mounting area from the same side as the mounting tool with respect to the stage surface, with an optical system and an image sensor arranged to satisfy shineproof conditions such that the plane parallel to the stage surface of the stage becomes the focal plane; an upward imaging unit for imaging the mounting object held by the mounting tool from the opposite side of the overhead imaging unit with respect to the stage surface; and calibration indicators arranged to be imageable by the overhead imaging unit and the upward imaging unit. An implementation control program that causes a computer to execute an implementation control step in which it adjusts the position of the implementation tool so that the implementation surface is at the same height as the indicator surface of the calibration index, causes the upward-viewing imaging unit to image the implementation surface, recognizes the reference position of the implementation based on the upward-view image output, adjusts the position of the stage so that the implementation surface of the planned implementation area is at the same height as the indicator surface, and implements the implementation onto the implementation surface based on the reference position.

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