JP2000269242A - Chip-bonding device and calibration method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a chip-bonding device to be very accurately and efficiently calibrated, without being affected by mechanical deformation and a temperature change in an environmental atmosphere. SOLUTION: A chip-bonding device is calibrated in a manner, where control parameters are corrected and updated, recognizing a suction hole provided to the pressure surface of the pressure head 2a of a bonding tool 2 to chuck a semiconductor chip and a lower calibration mark 4, provided on the top surface 6a of a transparent plate 6 with a two-visual field camera 3, and furthermore is corrected and updated, recognizing the suction hole and the calibration mark 4 with a single visual field camera 9, by making the bonding tool 2 descend at the camera 3 being on standby, where this calibration is carried out, only when a temperature detector 8 mounted on the two-visual field camera 3 detects a certain temperature above an allowable value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] 1. Field of the Invention [0002] The present invention relates to a chip bonding apparatus for bonding a semiconductor chip to a substrate and a calibration method in the chip bonding apparatus.

2. Description of the Related Art As is well known, in chip bonding, a semiconductor chip held by an upper bonding tool is attached to a substrate (for example, a liquid crystal substrate) supported by a bonding stage below the semiconductor chip. In a state where the bonding position is precisely positioned, bonding is performed by lowering the bonding tool. Therefore, prior to such bonding, for example, the alignment marks provided on the semiconductor chip and the substrate are recognized by a two-view camera, and the bonding stage is controlled to move in a predetermined manner so as to eliminate the displacement between the two alignment marks. In this case, the position of the semiconductor chip and the substrate is adjusted, and at this time, the dual-view camera is moved from the retracted position to the alignment mark recognition position or moved in the opposite direction to the retracted position. However, as the bonding proceeds one after another through these processes, changes in environmental conditions such as an increase in the temperature in the working room cause dimensional changes in each part of the device. Under the same conditions, errors occur in the alignment mark position recognition,
This makes high-precision bonding difficult. Therefore, in order to maintain the bonding accuracy in units of μm, calibration of the camera movement control system is performed as needed, and various calibrations have already been proposed. For example, in paragraphs [0036] to [0042] of JP-A-9-8104, a mark table is mounted on a Z table on which a bonding tool is mounted via a lifting device, and the lifting device is driven. The mark table is moved to the same level as the semiconductor chip held in vacuum by the bonding tool, and the two-view camera is moved below the mark table to adjust the calibration mark provided on the mark table. Then, after retreating the dual-view camera from there, the lifting device is driven to move the mark table to the same level as the circuit board supported by the lower bonding stage, and Recognize the mark by moving the two-view camera upwards,
There has been proposed a calibration method for correcting and updating preceding control parameters input to the movement control system of the camera based on predetermined control parameters obtained by both recognitions.

However, in this calibration method, the calibration mark is recognized at a position far apart from the position at which the alignment mark provided on each of the semiconductor chip and the substrate is recognized. Therefore, the two-field camera is moved to a position where one of the marks (for example, a calibration mark) is recognized, and is moved to a position where the other mark (for example, an alignment mark) is recognized. When the camera is moved X
The load (bending moment) acting on the Y table or the XYZ table is different, and the difference in the amount of bending due to this is
Calibration mark position recognition error
Calibration with even higher precision was hindered. In view of the above, the inventors of the present invention, in another patent application, provide a suction hole for holding and holding a semiconductor chip which is opened on a pressing surface of a bonding tool and a transparent plate of a bonding stage on which a transparent plate is mounted. In addition to recognizing the calibration lower mark with the two-field camera, the bonding tool is lowered from the upper standby position to bring the air intake hole closer to the calibration lower mark, and the lower side of the transparent plate. Proposed that the single-view camera recognizes the air intake hole and the lower mark for calibration, so that calibration can be performed with higher precision.However, in such a calibration method, Since the upper optical axis and the lower optical axis of the field-of-view camera are shifted, it is necessary to correct it. It has been considered. However, while the correction parameters required for this are empirically determined from the accuracy measurement results of the two-view camera, etc., they are susceptible to the effects of seasonal changes (changes in environmental temperature). In addition to the difficulty of maintaining a constant accuracy, trying to maintain the calibration accuracy at a constant level results in a longer calibration time and lower efficiency. If the number of calibrations is reduced, it is difficult to maintain constant accuracy, and there is a contradictory problem that cannot be solved. The present invention pays attention to such drawbacks, and as a result of intensive studies to solve the drawbacks, as a result, it has been found that there is a correlation between the shift amount of the upper and lower optical axes of the two-view camera and the camera temperature. The invention has been completed.

That is, according to a first aspect of the present invention, there is provided a chip bonding apparatus in which a suction hole for sucking and holding a semiconductor chip is opened in a pressurizing surface, and a vertical movement is performed. A bonding tool mounted so as to be able to move in a horizontal plane below the bonding tool, and a calibration tool provided on a transparent plate mounted on the bonding stage. When the bonding stage is positioned at the calibration execution position, the mark moves from the retracted position to between the bonding tool and the transparent plate to recognize the suction hole and the upper and lower calibration marks. Dual view camera and the bonding tool is on standby And a single-view camera that recognizes the air intake hole and the calibration lower mark from below the transparent plate in a state where the single-view camera is moved downward from the device and approaches or contacts the transparent plate. Temperature sensor is mounted on the two-view camera, and calibration is performed only when the temperature detector detects a temperature change exceeding an allowable level. Further, according to the calibration method in the chip bonding apparatus according to the present invention, as set forth in claim 7, a bonding stage disposed below a bonding tool having an intake hole for sucking and holding a semiconductor chip is provided. In the state where the camera is moved in the horizontal plane and positioned at the calibration execution position, the dual-view camera is moved from the retracted position to between the bonding tool and the transparent plate mounted on the bonding stage, so that the suction hole and the transparent glass are moved. Correcting and updating the preceding control parameter input to the camera movement control system based on the predetermined control parameter obtained by recognizing the lower mark for calibration provided on the board, and From the upper standby position to the lower position The camera movement based on predetermined control parameters obtained by recognizing the intake hole and the calibration lower mark with a one-view camera from below the transparent plate in a state of approaching or abutting on the transparent plate. In a calibration method in a chip bonding apparatus for correcting and updating a preceding control parameter input to a control system, a temperature of the two-view camera is detected, and only when a temperature change exceeding an allowable level is detected. The correction and update of the control parameters based on the recognition of the intake hole and the lower mark for calibration by the two-view camera, and the control parameters based on the recognition of the intake hole and the lower mark for calibration by the single-view camera. And performing a correction update. .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIGS. 1 and 2 which are perspective views, a view in which a two-view camera 3 is moved between a lower bonding stage 1 and an upper bonding tool 2 is shown. The lower mark 4 for calibration and the air inlet 10 are both recognized by the two-field camera 3. Note that the calibration lower mark 4 is provided on the transparent plate 6 (for example,
(A glass plate) on the upper surface 6a and the intake hole 1
Numeral 0 is provided on the pressing surface 2b of the pressing head 2a forming the tip of the bonding tool 2. The bonding stage 1 is mounted on the θ table 7a forming the uppermost stage of the XYθ table 7. Therefore, by driving the XYθ table 7, the X-axis direction, the Y-axis direction, or the XY-axis Direction (hereinafter, simply referred to as parallel movement) and rotated in a predetermined direction. On the other hand, the bonding tool 2 cannot be moved in the horizontal direction by a mechanism not shown, but is mounted so as to be vertically movable in the Z-axis direction (vertical direction), and heats the pressure head 2a to a predetermined temperature. In addition, a heater (not shown) is built-in, and an intake hole 10 for adsorbing and holding the semiconductor chip is opened in the pressing surface 2b of the pressing head 2a. The suction hole 10 is located on the vertical axis BB of the bonding tool 2, and one end of a pressure-resistant hose 11 is attached to the bonding tool 2 so as to communicate with the hole 10.
The other end is attached to a vacuum pump (not shown). In addition, the dual-view camera 3 has an X (not shown).
It is mounted on the YZ table. Therefore, this camera 3
Can be moved from the retreat position to between the bonding tool 2 and the transparent plate 6 by driving the XYZ table, and conversely from the retreat position to the retreat position. At this time, the height position of the two-view camera 3 is adjusted to a predetermined value by driving the Z table. Further, a temperature detection means 8 (for example, a thermocouple) is attached to the two-view camera 3 and a one-view camera 9
(For example, a CCD camera). The one-field camera 9 always has its imaging head positioned below the transparent plate 6. Also, bonding stage 1
And the upper surface 6a of the transparent plate 6 are provided so as to form a continuous plane (without forming a step). At the center of the upper surface 1a of the bonding stage 1, an intake hole 12 for adsorbing and holding a substrate (for example, a liquid crystal substrate) is opened. One end of the suction hole 12 communicates with a pressure-resistant hose 13 attached to the bonding stage 1, and the other end (not shown) of the hose 11 is attached to a vacuum pump. Therefore, the XYθ table 7 can be translated and rotated to position the bonding stage 1 at the calibration execution position as shown in the figure. However, such a calibration execution position depends on the visual field of the two-field camera 3 and the one-field camera 9. It is set at a predetermined position within the range, that is, within a range in which both cameras 3 and 9 can recognize both of the upper and lower calibration marks 5 and 4. In a state where the bonding stage 1 is positioned at the calibration execution position,
The transparent plate 6 is located below the bonding tool 2. The position of the calibration lower mark 4 provided on the transparent plate 6 is determined by the position of the air inlet 10 provided on the bonding tool 2 and the plane of the bonding stage. Are not located on the same vertical line. Hereinafter, in this state, the bi-view camera 3 is moved between the bonding tool 2 being moved to the upper standby position and the transparent plate 6 therebelow, and then the intake port 10 and the calibration The use mark 4 is recognized, and the preceding control parameter input to the camera movement control system is corrected and updated based on the predetermined control parameter obtained thereby. At this time, since the suction hole 10 for adsorbing and holding the semiconductor chip is recognized, the bonding tool 2 is attached prior to bonding (thermocompression bonding).
The two-view camera 3 is controlled to move in the same stroke as when the two-view camera 3 recognizes the alignment mark of the semiconductor chip held by suction and the alignment mark of the substrate supported by the bonding stage 1 therebelow. You. As described above, since all the marks are recognized at the same stroke position, there is no influence of the bending due to the load difference.
Subsequently, when the two-view camera 3 is moved from the mark recognition position between the bonding tool 2 and the transparent plate 6 to the retreat position on the right side, the bonding tool 2 is lowered from the upper standby position, thereby The pressing head 2a of the bonding tool 2 is brought close to or lightly against the transparent plate 6. Then, the intake hole 10 and the calibration lower mark 4 are recognized from below the transparent plate 6 by the one-field camera 9, and are input to the camera movement control system based on predetermined control parameters obtained thereby. The preceding control parameter is further corrected and updated.
Note that, through the recognition of the series of lower marks for calibration and the air holes, for example, the amount of deviation between the upper optical axis 3a and the lower optical axis 3b of the two-view camera 3 is obtained, and the obtained predetermined control parameters are obtained. , The preceding control parameter is corrected and updated. Calibration using the single-view camera 9 is for thermal deformation of the stage or head position, and can be performed as necessary at a lower frequency than that using a two-view camera with a high frequency of optical system deformation. Good. As described above, in the present invention, the calibration using the two-view camera 3 and the single-view camera 9 are performed.
Calibration is performed in two stages, that is, calibration using. Therefore, the calibration can be performed with higher accuracy than the conventional calibration while preventing the movement of the camera from being complicated. Further, as described above, in the present invention, since the movement control of the camera can be completed with a smaller number of times, the time required for calibration can be reduced. Note that such calibration is appropriately performed as necessary during the course of bonding (thermocompression bonding) semiconductor chips one after another to a substrate (not shown) such as a liquid crystal substrate supported by the bonding stage 1. Done in At this time, the calibration is performed by the temperature detecting means 8 attached to the two-view camera 3.
Is performed only when a temperature change exceeding an allowable level is detected.
Therefore, even if the two-field camera 3 moves between the bonding tool 2 and the transparent plate 4, the above-mentioned calibration is not performed when the temperature detecting means 8 does not detect a temperature change exceeding an allowable level. Therefore, the calibration can be performed at the optimal timing, and the number of times of the calibration can be reduced. Therefore, the calibration can be performed efficiently, and the calibration accuracy is kept constant, that is, the environment atmosphere Can be maintained with high accuracy even in the case where the temperature changes. As described above, in the present invention, the allowable temperature change is set based on the fact that there is a correlation between the shift amount α between the upper optical axis 3a and the lower optical axis 3b of the two-field camera 3 and the camera temperature. Therefore, the above-described effects can be obtained. Regarding the setting of the allowable temperature change, a heating test was performed on a plurality of two-view cameras 3 to determine the camera temperature difference t and the shift amount α of the optical axis. It was confirmed from the change per 1 ° C. that the deviation amount of the optical axis was about 2 to 6 μm. Therefore, it is also an example to calculate a temperature change that deviates from the allowable deviation of the optical axis based on this data and set the calculated temperature change as the allowable temperature change. As is well known, the two-view camera 3
When affected by the temperature of the surrounding atmosphere, the upper optical axis 3
a from the lower optical axis 3b. Therefore, since the temperature can be measured in advance and the temperature change allowable value can be calculated from the allowable value of the measurement deviation amount α, the camera temperature is measured by the temperature detecting means 8 such as a thermocouple, and the temperature change is higher than the allowable accuracy. It can be provided so that calibration can be performed only when At the time of the above-described bonding, the bonding stage 1 is moved to a position different from the calibration execution position, that is, the bonding execution position. This is X
Is performed by the drive control of the Yθ table 7 and, when it is moved to the bonding execution position, the alignment mark of the substrate held by the two-view camera 3 through the suction hole 12 of the bonding stage 1 by vacuum suction and the bonding tool. The alignment mark of the semiconductor chip (not shown) held by vacuum suction through the second suction hole 10 is recognized. Hereinafter, the bonding stage 1 is moved in the X and Y axis directions, that is, is moved in parallel and rotated so as to eliminate the displacement between the two marks, whereby the semiconductor chip is precisely positioned at the bonding portion of the substrate. And therefore,
Thereafter, the bonding tool 2 can be lowered by lowering to perform predetermined bonding. As described above, one embodiment has been described. In the present invention, the calibration using the single-view camera 9 and the two-view camera 3 are performed.
It does not matter which one is performed first. In addition to performing the calibration using the two-view camera 3 and the calibration using the single-view camera 9 in parallel, one view before or after the calibration using the two-view camera 3 is performed. The calibration using the camera 9 may be performed intermittently. Also, the calibration lower mark 4 may be in any form, but is generally easily recognized by a camera, and is provided with a heat-resistant resin printed mark or a hole for the mark for the heater. Things are selected. Further, the bonding tool 2 is not limited to a so-called heat tool provided with a heater, and may be a tool not provided with a heater. Further, the bonding stage 1 and the bonding tool 2 only need to be able to control the relative positional relationship between the horizontal direction and the rotation direction in the horizontal plane. In that sense, the bonding stage 1 is also required to be movable in the horizontal plane. As long as it can move, it may be mounted so that it can move only in the X-axis direction or the Y-axis direction. In that case, the mounting tool 2 is mounted so that it can move in the Y-axis direction or the X-axis direction. What is necessary is just to mount it further, and also to be able to rotate in addition to it. In addition, as long as the bonding stage 1 can support the substrate in a predetermined manner,
In place of the substrate fixing means such as the suction hole 12, another type of substrate fixing means may be provided, and the mounting of the transparent plate 6 on the stage 1 is performed by the one-field camera 9 from below the stage by the calibration lower mark. As long as it can recognize 4 and the intake hole 10, it may be provided in any form.
Further, the dual-view camera 5 is generally mounted on an XYZ table, but may be mounted on another table such as an X table, a Y table, an XY table, or an XYθ table as needed. The moving means of the bonding stage 1 may be only the XY table or only the θ table, and any combination of the X table, the Y table, and the θ table may be arranged vertically. The bonding tool 2 also has a Z
Not limited to tables, XYZθ, XYZ, Zθ, YZ
For example, various table combinations can be selected, and the one-field camera 9 may be other than a CCD camera. Further, as for the temperature detecting means mounted on the two-view camera 9, a thermocouple, a resistance temperature detector, and the like can be selected. Since the mechanism can be simplified, the bonding stage 1 and the single-view camera 9 are combined together ( It is preferable to mount them so that they can move in a horizontal plane (integrally), but they may be mounted so that they can be moved independently and independently of each other or only the bonding stage 1 can be moved. In addition, without mounting the bonding stage 1, only a gate-shaped transparent plate is mounted so as to form a camera path, and this is used as a bonding stage (a substrate is set on the upper surface thereof). The lower mark for calibration provided on the upper surface of the plate and the air inlet provided in the bonding tool may be recognized from below by a one-field camera (an imaging head is positioned in the camera passage). Often, and in that case, the single-view camera may be fixedly or movably mounted.

As described above, according to the present invention, the reduction of the camera movement control process and the intermittent calibration can shorten the calibration time, and also the alignment of the two-field camera and the positional difference at the time of calibration. Calibration can be performed with high accuracy without being affected by mechanical deformation due to moments generated from the robot. Furthermore, calibration can be performed at the optimal timing, and the number of calibrations can be reduced. Calibration can be performed, and the calibration accuracy can be kept constant, that is, high accuracy can be maintained even when the temperature of the environmental atmosphere changes. Since the number of calibrations can be reduced while maintaining high accuracy, production efficiency can be increased.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a recognition mode of a calibration lower mark in a chip bonding apparatus.

FIG. 2 is a perspective view showing a recognition mode of an intake hole in the chip bonding apparatus.

[Explanation of symbols]

 1: Bonding stage 2: Bonding tool 2b: Pressing surface 3: Two-view camera 4: Lower mark for calibration 6: Transparent plate 7: XYθ table 8: Temperature detection means 9: Single-view camera 10: Inlet hole

Claims (8)

[Claims] An air inlet for holding a semiconductor chip by suction is opened in a pressurized surface, and a bonding tool mounted so as to be able to move up and down, and to be movable in a horizontal plane below the bonding tool. A bonding stage, a lower mark for calibration provided on a transparent plate mounted on the bonding stage, and the bonding tool from a retracted position in a state where the bonding stage is positioned at a calibration execution position. And a two-view camera that moves between the transparent plate and the suction hole and the lower mark for calibration, and the bonding tool is moved downward from the upper standby position to approach the transparent plate. Or from below the transparent plate in the abutting state In a chip bonding apparatus provided with a one-view camera for recognizing the intake hole and the lower mark for calibration, a temperature detection unit is mounted on the two-view camera, and the temperature detection unit is configured to allow a temperature change exceeding an allowable range. A chip bonding apparatus characterized in that the calibration is performed only when the signal is detected. 2. The chip bonding apparatus according to claim 1, wherein the bonding tool includes a heater. 3. The apparatus according to claim 1, wherein the bonding tool is mounted so as not to move in a horizontal direction.
Or the chip bonding apparatus according to 2. 4. The chip bonding apparatus according to claim 1, wherein the bonding stage is mounted so as to be able to move in parallel. 5. The chip bonding apparatus according to claim 4, wherein the bonding stage is mounted so as to be rotatable. 6. The chip bonding apparatus according to claim 1, wherein the one-view camera is mounted so as to move integrally with the bonding stage. 7. A state in which a bonding stage disposed below a bonding tool having an air suction hole for holding a semiconductor chip by suction opened in a pressing surface is moved in a horizontal plane to be positioned at a calibration execution position. A bi-view camera is moved from the retracted position to between the bonding tool and the transparent plate mounted on the bonding stage to recognize the suction hole and the calibration lower mark provided on the transparent plate. Correcting and updating the preceding control parameter input to the camera movement control system based on the predetermined control parameter obtained by moving the bonding tool downward from the upper standby position and approaching the transparent plate Or, in the abutted state, one field of view camera from under the transparent plate A chip that corrects and updates the preceding control parameter input to the camera movement control system based on a predetermined control parameter obtained by recognizing the intake hole and the lower mark for calibration with the camera. In the calibration method in the bonding apparatus, the temperature of the two-view camera is detected, and only when a temperature change exceeding an allowable range is detected, the recognition of the intake hole and the lower mark for calibration by the two-view camera is performed. And updating the control parameters based on the recognition of the air inlet and the calibration lower mark by the one-field camera. 8. Before or after correcting and updating control parameters based on recognition of an intake hole and a lower mark for calibration by a two-view camera, based on recognition of the intake hole and the lower mark for calibration by a single-view camera. The calibration method according to claim 7, wherein the correction update of the control parameter is performed intermittently.