JP2002334899A - Method and equipment for inspecting bump height - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an equipment for efficiently inspecting the bump height with high accuracy. SOLUTION: Vertex of a bump 8 is irradiated with a line shape light beam from an irradiation 10, and in this state, images of the bump 8 and a base 9 on which the bump 8 is formed are imaged by means of a camera 20. Subsequently, distance d between a first position for imaging at the vertex of the bump 8 and a second position for imaging the base 9 by means of the camera 20 is calculated at an image processing section 2, and height h (=d/2) of the bump 8 with reference to the base 9 is calculated based on the distance d. Based on the calculated bump height h, a decision is made at a processing result deciding section 3 as to whether or not the bump height is normal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a bump height inspection method and an inspection apparatus for inspecting the height of a bump formed on a substrate, a chip or the like. More specifically, the present invention relates to a bump height inspection method and an inspection apparatus capable of performing a bump height inspection with high accuracy and efficiency.

[0002]

2. Description of the Related Art Conventionally, in mounting an LSI chip or the like, an electrical connection with a printed wiring board is made by using a bump. In order to perform sufficient bonding, it is necessary to keep the height of the bump at an appropriate value. This is because if the height of the bump is lower than the appropriate value, sufficient bonding cannot be performed, and the reliability of mounting is reduced. On the other hand, if the height of the bump is higher than the appropriate value, there is a possibility that a short circuit may occur with the adjacent bump. Therefore, it is checked whether the height of the bump formed on the wiring board or the like is appropriate. The inspection equipment used for this inspection measures the ring formed by the reflection of the ring illumination and estimates the height of the bump from the measurement result. The height of the bump is inspected using a method for estimating the height.

[0003]

However, in the inspection apparatus using the former method, the size of the ring formed by the reflection depends not only on the height of the bump but also on the surface state of the bump. Therefore, for example, when the bump is not a perfect spherical surface, the height of the bump cannot be accurately estimated from the size of the ring formed by the reflection. On the other hand, in the inspection device using the latter method,
The size of the shadow formed by the oblique illumination and the position of the image of the bump vertex do not have an absolute position reference, so that the inspection is performed by relative evaluation with a nearby bump. In addition, when the quality of the bump height is determined based on the error from the ideal value of the size of the shadow and the position of the image of the bump vertex, the error is very small, and this error is accurately detected. It is very difficult to do. For example, if the bump is not a perfect spherical surface, the above error cannot be detected accurately. For this reason, the conventional bump height inspection method and inspection apparatus have a problem that the bump height cannot be inspected with high accuracy.

On the other hand, there are a triangulation method and a projection method using a laser beam as a method for accurately measuring the height of a bump, and both methods require scanning using a laser beam. For this reason, it takes time to measure the height of only one bump, and it takes a considerable amount of time to inspect all the heights of the bumps formed on the substrate in large quantities. Inspection tact can not be satisfied. Therefore, it is not realistic to apply such a method to an inspection device.

Accordingly, the present invention has been made to solve the above-mentioned problems, and provides a bump height inspection method and an inspection apparatus capable of performing a bump height inspection with high accuracy and efficiency. That is the task.

[0006]

In order to solve the above-mentioned problems, a bump height inspection method according to the present invention is directed to a method of inspecting a linear light beam by applying a light beam to an optical axis and a base surface on which the bumps are formed. The top of the bump is illuminated so that the line makes a predetermined angle, and in that state, the top of the bump and the base surface are imaged using a vertically arranged area CCD camera. When the position where the vertex of the bump is imaged is set as the first imaging position and the position where the base surface is imaged is set as the second imaging position, the distance between the first imaging position and the second imaging position is calculated. The height of the bump is calculated with reference to the base surface based on the calculated distance. The “optical axis” means the center of the angular distribution of the irradiation light. The predetermined angle is 30 degrees to 6 degrees.
It may be about 0 degrees.

In this bump height inspection method, first, a linear light is applied to the top of the bump to be inspected by a predetermined angle between the optical axis and the normal to the base surface on which the bump is formed. Irradiation is performed. At this time, the linear light illuminates the bump top and the base surface. Then, in this state, the apex of the bump and the base surface are imaged by the area CCD camera.

Here, the linear light may be obtained by expanding the light irradiated from the laser light source by using a beam expander. By spreading the laser light with the beam expander in this manner, it is possible to irradiate linear light having a width of about 10 μm and having a small scattering component. Therefore, the width of the irradiation light is sufficiently smaller than the height of the bump (about 50 μm). For this reason, it is possible to minimize the influence of the light width and the irregular reflection component on the inspection accuracy. In addition, by making the irradiation light linear, the height of a plurality of bumps can be inspected by one image pickup. That is, the inspection can be performed efficiently.

Since the top of the bump is irradiated with linear light so that the optical axis of the irradiation light and the normal to the base surface form a predetermined angle, the area CCDs arranged vertically
The imaging position of the vertex of the bump in the camera is different from the imaging position of the base surface. In other words, when imaging is performed in a state where light is applied to the top of the bump, the position where the vertex of the bump is imaged and the position where the base surface is imaged are different. Therefore, assuming that the position where the apex of the bump is imaged is the first imaging position and the position where the base surface is imaged is the second imaging position, the distance between the first imaging position and the second imaging position is determined based on the imaging result. The distance can be calculated. And since the area CCD camera which performs imaging is arranged vertically, the distance between the first imaging position and the second imaging position is twice the height of the bump with respect to the base surface ( (See FIG. 2). Therefore, it is possible to calculate the height of the bump with reference to the base surface based on the calculated distance. That is, the height of the bump can be measured.

In addition, since the area CCD camera is arranged vertically, the distance between the first imaging position and the second imaging position is twice the height of the bump with respect to the base surface. This is always true regardless of the angle between the optical axis of the irradiation light and the normal to the base surface. Therefore, if an area CCD camera having a predetermined size is installed, the size of the area CCD camera can be changed even when the angle between the optical axis of the irradiation light and the normal to the base surface is changed. Instead, the height of the bump can be inspected simply by slightly moving the arrangement position in the vertical direction.

As described above, the present inspection method performs the height inspection by measuring the bump height, instead of performing the height inspection by estimating the bump height as in the conventional inspection method.
Therefore, the inspection can be performed with an accuracy that cannot be obtained unless a measuring instrument is used. Further, since the light applied to the bumps is linear, the inspection can be efficiently performed in a short time. From the above, according to the present inspection method, the bump height inspection is performed with high accuracy and efficiency.

In the bump height inspection method according to the present invention, the line-shaped light may be irradiated on the top of the bump so that an optical axis thereof and a normal to a base surface on which the bump is formed form a predetermined angle. , And in that state, the line CCD camera is moved in the vertical direction to capture the apex of the bump and the base surface.
When the position where the vertex of the bump is imaged is set as the first imaging position, and the position where the base surface is imaged is set as the second imaging position,
The distance between the first imaging position and the second imaging position may be calculated, and the height of the bump with reference to the base surface may be calculated based on the calculated distance.

That is, imaging of the apex of the bump and the base surface can be performed using a line CCD camera instead of the area CCD camera. With this method,
The same effect as the above-described method can be obtained. In addition,
A line CCD camera cannot obtain a two-dimensional image unless scanning is performed.
The camera is moving up and down. The reason for moving the line CCD camera in the vertical direction in this manner is to simplify the moving mechanism, and to make the distance between the first imaging position and the second imaging position equal to the distance between the bump and the base surface. This is to ensure that the relationship of twice the height always holds regardless of the angle between the optical axis of the irradiation light and the normal to the base surface.

Further, in the bump height inspection method according to the present invention, it is determined whether or not the bump height is normal by comparing the calculated bump height with an appropriate value. When it is determined that there is, it is preferable to notify that fact. Thereby, an operator or the like can easily remove a substrate or the like on the manufacturing line on which a bump having an abnormal height exists. In addition, as a notification method, a warning lamp, a warning buzzer, or the like can be given.

Further, the bump height inspection apparatus according to the present invention is characterized in that an irradiating means for irradiating the top of the bump with linear light and an imaging means for imaging the top of the bump and the base surface on which the bump is formed. In a state where the light from the irradiating unit is irradiating the top of the bump, the position where the vertex of the bump is imaged by the imaging unit is defined as the first imaging position, and the position where the base surface is imaged by the imaging unit is defined as the first position. When two imaging positions are set, a distance calculating unit that calculates a distance between the first imaging position and the second imaging position, and a bump height based on a base surface is calculated based on a calculation result of the distance calculating unit. And an image pickup unit is a vertically arranged area CCD camera.

Alternatively, the bump height inspection apparatus according to the present invention comprises: an irradiating means for irradiating the top of the bump with linear light; and an imaging means for imaging the top of the bump and the base surface on which the bump is formed. In a state where the light from the irradiating unit is irradiating the top of the bump, the position where the vertex of the bump is imaged by the imaging unit is defined as the first imaging position, and the position where the base surface is imaged by the imaging unit is defined as the first position. When two imaging positions are set, a distance calculating unit that calculates a distance between the first imaging position and the second imaging position, and a bump height based on a base surface is calculated based on a calculation result of the distance calculating unit. The height of the bump is calculated.
It may be characterized by including a camera and a moving mechanism for moving the line CCD camera in the vertical direction.

In these bump height inspection devices, the value calculated by the bump height calculation means is compared with an appropriate value of the bump height to determine whether the bump height is normal. It is preferable to further include a determination unit for determining the condition, and a notification unit for notifying that the determination is abnormal.

According to the bump height inspection apparatus having such a configuration, the bump height inspection can be performed accurately and efficiently as described above. Further, in a production line, an operator or the like can easily remove a substrate or the like on which a bump has an abnormal height.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The most preferred embodiment of an inspection apparatus using the bump height inspection method according to the present invention will be described below in detail with reference to the drawings.

First, a schematic configuration of the inspection apparatus according to the present embodiment is shown in FIG. The bump height inspection apparatus includes an imaging unit 1, an image processing unit 2, a processing result determination unit 3, a table control unit 4, and a table 5. Here, the imaging unit 1 is fixed at a fixed position, and the height of the plurality of bumps is sequentially inspected by moving the table 5 on which the inspection object 7 on which the bumps are formed is set. I have. In addition, each part of the bump height inspection apparatus is connected to each other, and the operation thereof is controlled based on each control signal.

As shown in FIG. 2, the imaging unit 1 includes an illumination device 10 and a camera 20, and irradiates light to a vertex of the bump 8 and a base 9 such as a substrate on which the bump 8 is formed. 8 and the base 9 are imaged. The illumination device 10 includes a laser light source 11 and a beam expander 12. Thus, the illumination device 10 can irradiate the vertex of the bump 8 with line light having a width of about 10 μm and having a small scattering component. In addition, when the angle between the optical axis of the irradiation light and the normal line of the base 9 is θ, the lighting device 10 has
It is arranged so that θ = 45 degrees.

On the other hand, as the camera 20, an area CCD camera is used. The camera 20 receives the specularly reflected light from the bump 8 and the base 9 with respect to the irradiation light irradiated from the irradiation device 10, thereby forming the bump 8.
And an image of the base 9. The camera 20 is arranged vertically as shown in FIG. Note that the angle between the optical axis of the specularly reflected light and the normal to the base 9 is also θ.
= 45 degrees. Further, the mounting angle θ of the imaging unit 1 with respect to the normal line of the base 9 is not limited to 45 degrees, but may be 30 degrees.
Any angle can be set as long as it is within the range of 60 degrees.

The image processing unit 2 calculates a distance d between a first imaging position at which the vertex of the bump 8 is imaged and a second imaging position at which the base 9 is imaged, based on the imaging result of the camera 20.
Is calculated to determine the height h of the bump 8 with reference to the base 9. The method for obtaining the bump height h will be described later.

The processing result determination section 3 determines whether or not the bump height h obtained by the image processing section 3 is normal. If there is an abnormality in the height h of the inspected bump, the processing result determination unit 3 notifies the abnormality by sound or light.

The table 5 firmly fixes the inspection object 7 such as a substrate on which bumps are formed. The table 5 is provided with a moving mechanism 6, which moves based on a control signal from the table control unit 4. In the present embodiment, the table control unit 4 controls the table 5
Each time one imaging by the imaging unit 1 is completed,
It can be moved by the bump formation pitch p (see FIG. 3).

If the inspection is performed with the moving amount of one step of the table 5 reduced, the inspection accuracy can be improved. However, in this case, the inspection time becomes longer. For this reason, it is preferable to perform the inspection by reducing the moving amount for one step of the table 5 only near the vertex of the bump 8 and increasing the moving amount in other portions. By setting the amount of movement of the table 5 to such a setting, the inspection time can be relatively shortened while increasing the inspection accuracy.

Next, a description will be given of a method of inspecting the bump height using the inspection apparatus configured as described above. First, the test object 7 on which the plurality of bumps 8 are formed as shown in FIG. 3 is fixed at a predetermined position on the table 5. When the test object 7 is set on the table 5, the table 5 is placed at a position where the irradiation light from the lighting device 10 hits the vertices of the plurality of (one line) bumps 8 based on the control signal from the table control unit 4. Moved. When the movement of the table 5 is completed, light is emitted from the irradiation device 10 to each bump 8 (for one line). At this time, since the irradiation device 10 emits the line light, a plurality of (one line) bumps 8 can be imaged by one imaging. Therefore,
Since a plurality of (one line) height inspections of the bumps 8 can be performed from one imaging result, the inspection efficiency is very high.

Then, each of the bumps 8 is
The camera 20 captures images of the bumps 8 and the base 9 in a state where light is irradiated to the apex and the base 9. That is, in the camera 20, reflected light is received by the CCD provided in the camera 20, and image processing is performed based on light amount data relating to the amount of received light. As a result, an imaging result on the bump 8 and the base 9 as shown in FIG. 4 is obtained. FIG. 4 shows data on one of the bumps obtained as an imaging result. Here, since the irradiation device 10 emits light having a width of about 10 μm, the line width in the imaging result is 10 μm.
That's all. Therefore, the camera 20 performs processing so as to output the result based on the center of the line width.

When the camera 20 obtains the imaging results for the bumps 8 and the base 9, the data is input to the image processing unit 2. Then, in the image processing unit 2, first, the imaging data is cut out in the areas A, B, and C shown in FIG. Here, the areas A and C correspond to the second imaging position, and the area B corresponds to the first imaging position. Therefore, the area A,
In C, the imaging data of the base 9 is cut out, and in the area B, the imaging data of the vertex of the bump 8 is cut out. As a result, imaging data as shown in FIG. 5 is obtained.

Next, the bump height h is calculated based on the image data of FIG. That is, the distance d between the first imaging position and the second imaging position is calculated, and the bump height h is obtained based on the calculation result. As is clear from FIG.
The distance d between the imaging position and the second imaging position is d = h × 2. That is, the distance d is twice the bump height h.
By arranging the camera 20 vertically in this manner, the distance d can be obtained regardless of the incident angle of the light emitted from the irradiation device 10.
And a bump height h, a relationship of d = h × 2 is always established. Therefore, the bump height can be accurately measured for any incident angle only by moving the position of the camera 20 up and down.

As described above, since the distance d is d = h × 2, the bump height h is h = d / 2. As described above, the present inspection apparatus can measure the bump height h, which cannot be measured by the conventional inspection apparatus.
When calculating the distance d, the imaging data of the base 9 cut out in each of the regions A and C has a deviation (for example, when there are irregularities such as wiring on the base, or when the base is inclined). In such cases, the average value of both data may be used.

When the image processing unit 2 calculates the bump height h, the result is input to the processing result determination unit 3. Then, the processing result determination unit 3 determines whether the height of the bump 8 is normal by comparing the appropriate value of the bump height stored in advance with the calculated value h. When the processing result determination unit 3 determines that the height of the bump 8 is abnormal, the processing result determination unit 3 notifies the fact. With this notification, the defective product is removed from the production line by the operator. In addition, it is also possible to install a removing device for removing defective products from the production line, and automatically remove defective products from the production line by inputting a notification signal from the processing result determination unit 3 to the removing device. is there.

When the height inspection of the bumps 8 for one line is completed in this way, a control signal is transmitted from the table control unit 4 to the moving mechanism 6 to perform the height inspection of the bumps 8 for the next line. Is done. The moving mechanism 6 is driven based on the control signal from the table control unit 4, and the table 5 moves by the bump formation pitch p (see FIG. 3). Then, the height inspection of the bump 8 on the next line is performed by repeating the above operation. Thereafter, the above-described operation is sequentially repeated in the inspection apparatus, and the inspection of the height of the bumps on the inspection object 7 is completed.

As described above, the present inspection apparatus can measure the height of the bump. Therefore, it is possible to perform an inspection of an accuracy that cannot be obtained unless a height measuring device is used. Further, the height of a plurality of bumps (for one line) can be inspected by one imaging. That is, according to the present inspection apparatus, the bump height inspection can be performed with high accuracy and efficiency.

Next, a modified example according to the above embodiment will be described. This modification is different from the above embodiment in the configuration of the camera. Other configurations are basically the same. Therefore, the same components as those in the above embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 6, a line CCD camera 31 is used as the camera 30 in the modified example.
Therefore, the camera 30 cannot obtain a two-dimensional image unless scanning is performed. For this reason, the camera 30 is provided with a moving mechanism 32 so that scanning can be performed in a vertical direction (a direction orthogonal to the base 9). The scanning range of the camera 30 is the bump 8
May be set so that the vertex and the base 9 can be imaged.

Here, it is possible to scan the camera 30 in a direction parallel to the imaging surface thereof, but in such a case, the mechanical configuration of the moving mechanism 32 becomes complicated. Therefore, in order to simplify the mechanical configuration of the moving mechanism 32, the camera 30 is configured to scan vertically. Further, by adopting a configuration in which the camera 30 is scanned in the vertical direction in this manner, as described above, regardless of the incident angle of the light emitted from the irradiation device 10, the distance between the distance d and the bump height h can be increased. , The relation of d = h × 2 can always be established. For this reason, the scan range,
More precisely, the distance for moving the camera 30 is always constant.

In such a camera 30, as in the case of the area CCD camera described above, an imaging result on the bump 8 and the base 9 as shown in FIG. 4 is obtained. Then, the same processing as in the above embodiment is performed to measure the bump height h.

As described in detail above, the bump height inspection apparatus according to the present embodiment includes an irradiation device 10 for irradiating light to the apex of the bump 8 from obliquely above, and receives the specularly reflected light. Accordingly, the image pickup unit 1 includes the camera 8 that images the bumps 8 and the base 9. Therefore, in the camera 20, the first imaging position at which the vertex of the bump 9 is imaged is different from the second imaging position at which the base 9 is imaged. Then, the distance d between the first imaging position and the second imaging position is calculated by the image processing unit 2, and the height h of the bump 8 with respect to the base 9 based on the distance d.
Is calculated. Thereafter, the processing result determination unit 3 determines whether the bump height is normal based on the calculated value of the bump height h. As described above, according to the bump height inspection apparatus according to the present embodiment, the value of the bump height h is calculated to perform the height inspection, so that the accuracy of the inspection result cannot be obtained unless a height measuring device is used. Is obtained.

The light emitted from the illumination device 10 to the apex of the bump is spread in a line by the beam expander 12. Therefore, the camera 20 can perform a plurality of (one line) bump height inspections by one image pickup. Therefore, according to the bump height inspection apparatus according to the present embodiment, the bump height inspection can be efficiently performed.

Further, since the camera 20 is arranged vertically, the distance d between the first imaging position and the second imaging position does not depend on the incident angle of the light emitted from the irradiation device 10 to the bump 8. A relationship of d = h × 2 always holds between the bump height h. Therefore, the bump height can be accurately measured for any incident angle only by slightly moving the position of the camera 20 up and down.

The present embodiment is merely an example, and does not limit the present invention. Therefore, of course, the present invention provides various improvements without departing from the gist thereof.
Deformation is possible. For example, in the above embodiment, the case where the present invention is used for testing the height of a bump formed on a substrate has been described. However, the present invention is not limited to this, and the bump formed on an IC chip, The present invention can also be applied to the inspection of the height of bumps, the inspection of the height of bumps formed for interlayer connection, and the like. Further, in the above embodiment, only the bump height inspection is performed alone, but the wiring pattern inspection and the bump height inspection can be performed simultaneously.

[0043]

As apparent from the above description, according to the bump height inspection method and the inspection apparatus of the present invention, the inspection of the bump height can be performed with high accuracy and efficiency.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an inspection device according to an embodiment.

FIG. 2 is a diagram schematically illustrating an arrangement position of an imaging unit.

FIG. 3 is a diagram for explaining an imaging method at the time of inspection.

FIG. 4 is a diagram showing an imaging result.

FIG. 5 is a diagram showing a result obtained by cutting out the imaging result of FIG. 4 in a specific area.

FIG. 6 is a diagram schematically illustrating an arrangement position of an imaging unit in an inspection device according to another embodiment.

[Description of Signs] 1 imaging unit 2 image processing unit 3 processing result determination unit 7 inspected object 8 bump 9 base 10 irradiation device 11 laser light source 12 beam expander 20 camera

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Claims (6)

[Claims] A linear light is irradiated on the top of a bump so that its optical axis and a normal to a base surface on which the bump is formed form a predetermined angle. An image of the apex of the bump and the base surface is taken by using the arranged area CCD camera. At this time, the position where the apex of the bump is taken as the first imaging position by the area CCD camera, and the position where the base surface is taken as an image. Calculating a distance between the first imaging position and the second imaging position when the second imaging position is set, and calculating a bump height based on the calculated distance based on the base surface; A bump height inspection method. 2. A line-shaped light is applied to the top of a bump so that its optical axis and a normal to a base surface on which the bump is formed make a predetermined angle. By moving the camera in the vertical direction, the vertex of the bump and the base surface are imaged. At this time, the position where the vertex of the bump is imaged is set as the first imaging position by the line CCD camera, and the base surface is imaged. When the position is the second imaging position, the distance between the first imaging position and the second imaging position is calculated, and the height of the bump is calculated based on the calculated distance with reference to the base surface. A bump height inspection method. 3. The bump height inspection method according to claim 1, wherein the calculated bump height is compared with an appropriate value to determine whether the bump height is normal. A bump height inspection method, comprising: judging, and, if it is judged to be abnormal, notifying that fact. 4. Irradiating means for irradiating linear light to the top of the bump; imaging means for imaging the top of the bump and a base surface on which the bump is formed; In a state where the top is illuminated, a position where the vertex of the bump is imaged by the imaging unit is a first imaging position, and a position where the base surface is imaged by the imaging unit is a second imaging position. Distance calculation means for calculating a distance between the first imaging position and the second imaging position; and bump height calculation for calculating a height of the bump based on a base surface based on a calculation result of the distance calculation means Means, wherein the image pickup means is an area CCD camera arranged vertically. 5. An irradiating means for irradiating linear light to the top of the bump; an imaging means for imaging the top of the bump and a base surface on which the bump is formed; In a state where the top is illuminated, a position where the vertex of the bump is imaged by the imaging unit is a first imaging position, and a position where the base surface is imaged by the imaging unit is a second imaging position. Distance calculation means for calculating a distance between the first imaging position and the second imaging position; and bump height calculation for calculating a height of the bump based on a base surface based on a calculation result of the distance calculation means A bump height inspection apparatus, comprising: a line CCD camera; and a moving mechanism that moves the line CCD camera in a vertical direction. 6. The bump height inspection apparatus according to claim 4, wherein the value calculated by the bump height calculation means is compared with an appropriate value of the bump height. A bump height inspection apparatus, further comprising: a determination unit for determining whether or not the height is normal, and a notification unit for notifying that the determination is abnormal by the determination unit. .