JPH07302825A - Wire bonding inspection equipment - Google Patents

Abstract

PURPOSE:To make it possible to input positional coordinate data for accurate inspection by setting a setting reference point based on an image data and CAD data by obtaining the image data by positioning photographing device based on CAD data. CONSTITUTION:Coordinates of alignment point confirms the presence or absence of data from unfilled information by a central processing unit 20 as same as setting data of a carrier portion. Thereafter, the data are read in the central processing unit 20, an XYZ stage 21 is moved to a position where the image of a portion with the coordinates at the center can be taken out by a photographing device 13, focusing treatment is performed and the image is taken in for each alignment point. The image taken in is analyzed by an image processing unit 23, is converted to an image with the characteristics extracted and compared into a characteristics extracted image processed in the same manner from the CAD data, and is stored again in a coordinate data storing unit 35 together with deviation correcting coordinate data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire bonding inspection device which facilitates a teaching operation prior to inspection.

[0002]

2. Description of the Related Art Conventionally, semiconductor products such as LSI have been integrated year by year, and the progress of their manufacturing technology has been remarkable. In particular, in the manufacturing process of the semiconductor circuit itself, that is, in the so-called pre-process, automation technology has been largely adopted, and unmanned processes have been unmanned.

On the other hand, although the wire bonder is being automated even in the wire bonding process which is a post-process, the present condition is that the inspection is solely dependent on the visual inspection. An example of an automatic inspection device as disclosed in Japanese Patent Laid-Open No. 5-160230 has been reported, and an electronic module after wire bonding has been reported.
By scanning the electronic module using an image pickup device such as a CCD camera to capture an external image and performing arithmetic processing by an image processing device and a central processing unit, the positions, outer dimensions and wire portions of the first bond portion and the second bond portion. It is possible to automatically measure the shape of the locus of.

Here, in such an apparatus, a coordinate point for scanning the image pickup apparatus on the electronic module and a reference coordinate for making a pass / fail judgment of whether or not the first bond portion and the second bond portion are in correct positions are generally used. It is necessary to input by the work called teaching.

FIG. 4 shows an example of the configuration of a conventional wire bonding inspection apparatus, and the actual operation will be briefly described below. The carrying unit 12 is set to a position, which is manually or numerically controlled, according to the dimensions of the lead frame 2, which is the object to be tested, such as the width and feed pitch, and then the lead frame 2 is set and is carried to the inspection area. . Subsequently, the XYZ stage 21 is controlled to move the image pickup device 13 to a position where an image of the lead frame 2 can be captured, and then focus adjustment is performed by an autofocus device (not shown) to display the image on the display monitor 33.

The operator operates the input device 34 for each of the alignment point, the first bond portion, and the second bond portion based on the image displayed on the display monitor 33 to obtain the positional information on the central processing unit 20.
Take in one place each. The position information here is output as a result of analyzing the projected video by the image processing device 23, and the XYZ stage 21 when the video is captured.
It is obtained by performing arithmetic processing by the central processing unit 20 on the basis of the output of the position coordinates of, and the obtained position information is immediately stored in the coordinate data storage device 35.

[0007]

However, in the above-mentioned conventional example, since it is necessary for the operator to input the position coordinate data one by one, it requires skill to operate the apparatus, and
It takes a lot of time for the operation, and the operator needs to pay attention to the display when performing the teaching work.

Further, in the above-mentioned conventional example, since the position coordinate data of a specific lead frame 2 is stored and the measurement is carried out with the data as a reference, it is necessary to select and prepare a sample suitable for the reference. However, there is a drawback that an error from the design value of the sample itself selected here and an erroneous input by the operator are directly reflected in the measured value.

In the case of a wire bonder, as disclosed in Japanese Unexamined Patent Publication (Kokai) No. 5-31589, an example in which CAD data is read and then an actual electrode pad or lead image is taken in and the data is corrected and stored is also reported. However, in the case of the inspection device, since the inspection object is the semiconductor chip after the bonding process, it is difficult to recognize the shape of the pad and the lead, and it is difficult to use the same method. The range is also limited to the electrode pad and the lead position, and the above problems remain for other items.

In view of the above problems in the prior art, it is an object of the present invention to enable input of position coordinate data for inspection in a wire bonding inspection device that does not impose an operator's burden and enables accurate inspection. Is to

[0011]

To achieve this object, according to the present invention, there is provided a wire bonding inspection apparatus for automatically inspecting a connection state of a wire of a semiconductor chip after wire bonding. Positioning means for positioning the semiconductor chip at a preset measurement reference point, and driving control of the imaging device and the positioning device to obtain image data at each measurement reference point, and based on this data, information regarding the connection state is obtained. In the wire-bonding inspection apparatus having a processing means for outputting, the processing means sets the imaging device to the semiconductor chip after wire-bonding based on CAD data of the semiconductor chip and wire bonding, for example, alignment mark data. Position, get the image data, and Wherein said is for setting the reference point on the basis of the CAD data and the.
Bonding data of wire bonding may be used instead of the CAD data. The positioning means usually comprises a carrying means for holding and carrying the lead frame to which the semiconductor chip is wire-bonded, in which case the processing means carries out the carrying based on the information contained in the CAD data or the bonding data. The drive control of the means can be performed. The CAD data and the bonding data can be used, for example, via a CAD data reading device or a bonding data reading device. As the measurement reference point, the center of the alignment mark, the center or contour of the electrode pad of the semiconductor chip, the center or contour of the lead, etc. are used. The information for controlling the drive of the transfer means includes the width, length, feed pitch of the lead frame included in the CAD data, the size of the magazine storing the lead frame, the rail width of the transfer means included in the bonding data, and the feed. The pitch, the number of semiconductor chips on the lead frame, etc. are used.

[0012]

In the present invention, in so-called teaching work, data is not created by performing actual measurement,
First, using a reading device or the like, numerical data based on design values such as CAD data or already digitized position coordinate data such as bonding data is introduced into the processing device, and stored in a coordinate data storage device, for example. Keep it. After that, external dimension data such as the width of the lead frame and the feed pitch is selected from the coordinate data, extracted, and used for positioning the conveying means. Further, the positions of the electrode pads and the positions of the leads on the semiconductor chip are extracted from the coordinate data and stored again as the data of the measurement reference point for inspection. This data is corrected by the image data obtained for the actual wire-bonded semiconductor chip.

According to this, the operator controls the XYZ stage while gazing at the display monitor and is relieved of the work of inputting the position coordinates one by one, and the position coordinates such as the measurement item and the judgment allowable value used for the pass / fail judgment are released. Only the data other than the data can be input and stored in the device, and the teaching work can be completed.

[0014]

1 is a block diagram of a wire bonding inspection apparatus according to an embodiment of the present invention. In the figure, 1 is a semiconductor chip after wire bonding which is an object to be inspected, 13 is an image pickup device for capturing an image of the semiconductor chip 1, 11 is an optical device including an autofocus device, an illumination device and the like (not shown), 21 Is an XYZ stage for positioning the image pickup device 13 relative to the semiconductor chip 1, 12 is a transport device for transporting an object to be inspected, 23 is an image processing device for analyzing a captured image, 20
Is a central processing unit for calculating and controlling, and 36 and 37 are a bonding data reader and a CAD data reader, respectively. The inspection procedure will be described below with reference to FIG.

First, a storage medium such as a floppy disk or ROM storing CAD data is set in the CAD data reading device 37, and the CAD data is read in accordance with a command from the central processing unit 20. The read data is stored in the coordinate data storage device 35 after the information required for the inspection is selected by the central processing unit 20 and arranged in a format easily accessible by the central processing unit 20. When the information is not satisfied, that is, when the amount of information in the CAD data is insufficient, the central processing unit 20 sorts out the unsatisfied information (hereinafter referred to as unfilled information) and simultaneously coordinates data. After being stored in the storage device 35, each part of the inspection device is set based on the information stored here, and the inspection and the quality determination are sequentially performed.

First, as a first procedure, the setting of the transport device 12 is performed. The central processing unit 20 confirms the unfilled information and confirms whether the data necessary for setting the transporting device 12, that is, the width, length, feed pitch of the lead frame and the size of the magazine for accommodating the lead frame are stored. After that, those data are transferred from the coordinate data storage device 35 to the call conveying unit control device 22 and the setting of the conveying device 12 is executed. However, if it is found that the data is insufficient when the unfilled information is confirmed, the contents of the insufficient data are displayed on the display, and the operator manually inputs the insufficient data according to the display, or the illustration provided in the carrier device 12 is performed. The lack of data is compensated by automatically measuring the dimensions of the lead frame 2 as the object to be inspected and the magazine (not shown) that accommodates the lead frame using an automatic sizing device. The data in which the deficiency is compensated is confirmed by the operator that there is no re-correction, and then stored again in the coordinate data storage device 35 in an updated form, and the lead frame 2 is stored on the basis of the data obtained as described above. It is transported to the inspection area.

Next, as the second procedure, the alignment points are set. Generally, in a wire bonding inspection apparatus, at least n or more reference points are set on the object to be corrected in order to correct manufacturing / assembling errors and positioning deviations of the object to be measured in advance, before the inspection. An operation called so-called alignment is performed in which the deviation of these reference points is measured and the deviation amount here is subtracted from the measured value as an offset amount.

In this inspection apparatus as well, it is necessary to perform alignment for each of the semiconductor chip 1 and the lead frame 2 as the inspection object, so a reference point (hereinafter referred to as an alignment point) for performing the alignment is set.

Since the semiconductor chip 1 is adhesively fixed onto the lead frame 2, when the lead frame is used as a reference, the semiconductor chip is compared with the data at the time of design as shown in FIG. Deviation of moving component and θ
It is fixed with a deviation of the rotation component of. Furthermore, FIG.
As shown in FIG. 5, the transport unit 12 is also installed with an inclination component with respect to the moving axis of the XYZ stage 21. Further, considering that the semiconductor chip 1 itself is also curved and deformed with a height difference of several tens of μm, the image captured at each alignment point based on the coordinates of CAD data is CAD.
It is considered that the image obtained by the simulation on the data has a displacement of several tens of μm.
Even if you think about the lead frame 2,
It is considered that, in addition to the manufacturing error and the deformation, the positional deviation of several tens μm to one hundred and several tens μm occurs due to the backlash of the transport device 12 and the transport error.

In this inspection apparatus, the following method is used in order to correct in advance the deviation amount due to the setting of the conveying device 12 from the deviation amount. The coordinate of the alignment point is read by the central processing unit 20 from the unfilled information to confirm the presence or absence of the data, like the transport unit setting data, and then read into the central processing unit 20 and the image pickup device 13 captures the image of the portion centered on the coordinate. The XYZ stage 21 is driven to a position where it is possible to perform focusing processing by an autofocus device provided in the optical device 11, and then an image is captured for each alignment point. The captured image is analyzed by the image processing device 23, converted into an image in which feature points are extracted, and then compared with a feature point extraction image similarly processed from CAD data, and coordinate data storage together with correction coordinate data of the amount of deviation. It is stored again in the device 35.

As a result of searching the unfilled information, if the coordinate data of the alignment point is not stored or the data is insufficient, the contents of the missing data are displayed on the display monitor 33 and input by the operator. Instruct. Even if the coordinates of the alignment point are stored in the coordinate data storage device 35, if the pattern on the semiconductor chip 1 has repetitiveness or the contrast of the pattern itself is low, for example. As a result of analyzing the captured image and extracting the characteristic points, it is determined that the number of characteristic points is small, and it may not be possible to use them as alignment marks. Even in this case, the comment is displayed on the display monitor 33 as in the case where the data is insufficient, and the operator performs the input work according to the display.

Further, as the third procedure, the data regarding the positional information of the electrode pad or / and the lead is set. The position of the electrode pad or / and the lead also deviates from the coordinates based on the CAD data, as in the case of the alignment point. However,
It is ideal that the electrode pad has a constant relative position with respect to the alignment point on the semiconductor chip 1 and the lead position also has a constant relative position with respect to the alignment point on the lead frame. Regarding the position information of the lead, relative coordinates with respect to the alignment point are calculated from the CAD data and stored in the coordinate data storage device 35. Then, the unfilled information is searched again to confirm whether the coordinate data is complete, and the input of the coordinate data is completed.

Items other than coordinate data, such as inspection items,
Items such as the number of chips to be inspected and the allowable range for acceptance / rejection determination are input by the operator from the input device 34 after inputting the coordinate data and are collectively stored in the coordinate data storage device 35. Finally, check again to finish the teaching work.

Although the actual inspection process is started after the teaching work is completed as described above, the contents and method of the inspection have been reported in Japanese Patent Laid-Open No. 5-160230, so that the flow of the inspection process will be described here. A brief description will be given below using 1.

When the operator issues a measurement start command to the central processing unit 20 using the input device 34, the display monitor 33 displays a list of semiconductor chip types for which teaching has already been completed. Input device 3 by selecting the product type to be inspected from the list
Enter in 4. The central processing unit 20 calls the teaching data of the selected product type from the coordinate data storage unit 35, and after confirming with the operator whether or not the data has been changed, the measurement is started.

First, as the first procedure, the setting of the transport device 12 is performed. The central processing unit 20 uses the data necessary for setting the transfer device 12, that is, the width of the lead frame,
The data such as the length, the feed pitch, and the size of the magazine for accommodating the lead frame are transferred to the transport unit controller 22 to set the transport device 12. However, also here, as in the case of teaching, the lead frame 2 to be measured and a magazine (not shown) for accommodating the lead frame 2 are manually input by an operator or using an automatic adjusting device (not shown) provided in the conveying device 12. It goes without saying that the setting of the transport device 12 may be performed by automatically measuring the dimension of. When the operator sets the lead frame 2 to be inspected or the magazine accommodating the lead frame 2 in the transport device 12 after setting the transport device 12, the lead frame is automatically transported to the inspection position.

Next, alignment is performed as a second procedure. The central processing unit 20 issues a command to the stage control unit 31 to move the XYZ stage 21 to a position where the image of each taught alignment point can be captured by the imaging device 13, and auto-focusing and image capture are performed for each alignment point. . Each image captured here is analyzed by the image processing device 23, and the semiconductor chip 1 and the lead frame 2 are analyzed.
The amount of deviation in each XYZ axis direction, the rotation angle, the tilt angle, and the contraction degree are calculated. Furthermore, at least 4 on the semiconductor chip 1
The curved coordinates are calculated by measuring and analyzing the spatial coordinates of the surface of the semiconductor chip 1 at points or more, and at the same time, the equation is calculated by approximating the surface of the semiconductor chip 1 to a geometric curved surface such as a spherical surface. .

According to the CAD data, since the surface of the semiconductor chip 1 is generally a plane, the position information of the electrode pads stored in the coordinate data storage device 35 is also composed of points on one plane. . Here, the coordinates obtained by transferring the points on these planes onto the approximate curved surface obtained above are calculated in the central processing unit 20, and thereafter, the measurement is performed based on the coordinates obtained here. As a matter of course, the Z coordinate can be easily obtained by giving the (X, Y) coordinates for any point not included in the CAD data.

Further, in the lead frame, the individual inner leads may be locally bent, and it is meaningless to approximate the curved surface. Therefore, only the deviation amount in each of the XYZ axis directions, the rotation angle, and the tilt angle are corrected. And

As the third procedure, the inspection of the first bond portion and / or the second bond portion is performed. Here, similarly to the case of the alignment point, the image of the first bond portion and / or the second bond portion is captured by the imaging device 13 and analyzed by the image processing device 23, and the respective first bond portion and / or the second bond portion is analyzed. For example, measured values such as the size, the amount of deviation from the reference position, the amount of protrusion from the electrode pad or / and the lead, the contact with the adjacent bond portion, the amount of deformation of the lead, and the like can be obtained. When capturing an image, a plurality of bond portions are projected on the same screen, and the position of the XYZ stage 21 is calculated by the central processing unit 20 so that the number of times of capturing the image is minimized. Is analyzed in parallel in a short time.

Next, as a fourth procedure, the measurement of the wire portion is started. In teaching, the coordinates of the first bond portion and the second bond portion are given as the center coordinates of the electrode pad and the center coordinates of the lead, but the trace of the wire is Not given. Therefore, when the third procedure is completed, the central processing unit 20 calculates the locus of the line segment connecting the first bond portion and the second bond portion and stores it as the predicted wire existence position. However, if the coordinates of the first bond part and / or the second bond part cannot be determined, such as when the first bond part and / or the second bond part is not inspected or when the first bond part and / or the second bond part are not found even after the inspection, the electrode pad by teaching These are substituted by the center coordinates of and the center coordinates of the lead. Images are captured again along the trajectory of each wire obtained above to calculate the measured values such as the bending of the wire, the three-dimensional shape of the wire, the contact and spacing between adjacent wires, and the gap between the semiconductor chip and the wire. However, it goes without saying that the time can also be shortened by incorporating a plurality of wires in the same screen or by parallel processing of image analysis.

Steps 3 and 4 are repeated until the measurement is completed for all the wires of one semiconductor chip.

As a fifth procedure, inspections for items other than wires are performed. The imaging device 13 is used as the XYZ stage 2
1 is moved to the center position of the semiconductor chip 1 to capture the entire image of the semiconductor chip. From this image, the image processing device 23 processes to remove the wire portion, and further compares it with the image of the wiring pattern to detect scratches and dust on the semiconductor chip, or obliquely incident slit light or laser light (not shown). By scanning the semiconductor chip with light, scratches and dust are confirmed and the position and size are measured. Finally, the image pickup device 13 is scanned on the outer periphery of the semiconductor chip to capture an image of the periphery of the semiconductor chip, and the image processing device 23 analyzes it to measure the protrusion amount of the paste (not shown) and completes the inspection per chip.

After repeating steps 2 to 5 of the inspection process for all the semiconductor chips designated in advance by the operator, the lead frame 2 is ejected from the carrier device 12 and the whole process is completed. In 20, in parallel with the arithmetic processing during the inspection, the measurement result is compared with a pass / fail judgment reference value set in advance during teaching. This comparison result is displayed on the display monitor 33 each time the measurement of one semiconductor chip is completed, and when the whole measurement is completed, the statistical processing of the average value, variance, maximum value, minimum value, etc. in each measurement item is also centralized. It is automatically performed by the processing device 20 and is stored as a file of inspection results in an inspection result storage device (not shown). Therefore, by connecting or integrating this inspection device and the central processing unit of the wire bonder, it is possible to monitor the deviation of the bonding point of the wire bonder over time and automatically correct the deviation amount by correcting the bonding data. Becomes

In this embodiment, a so-called off-line system using a medium such as a floppy disk is mentioned as a means for transmitting data to the CAD data reading device or the bonding data reading device.
An online method using an ocal area network) or the like may be used.

Further, although the inspection device is treated as a single device in this embodiment, the same result can be obtained by sharing the wire bonder and the central processing unit and / or the coordinate data storage device or by integrating the devices. Obtainable.

[0037]

As described above, according to the present invention, the operator controls the XYZ stage while gazing at the display monitor, and is relieved from the work of inputting position coordinates one by one, and can be used for measurement items and pass / fail judgment. Only the data other than the position coordinate data such as the judgment allowable value to be used can be input and stored in the device, and the teaching work can be ended. That is, the simplification and automation of the operation is advanced, and the coordinate input work, which occupies 50 to 90% of the teaching work, can be omitted, and the incorrect input of the teaching data due to the defective sample or the human error by the operator is prevented. can do.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a wire bonding inspection apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of semiconductor chip rotation correction in the apparatus of FIG.

FIG. 3 is an explanatory diagram of semiconductor chip tilt correction in the apparatus of FIG.

FIG. 4 is a block configuration diagram of a wire bonding inspection device according to a conventional example.

[Explanation of symbols]

1: semiconductor chip, 2: lead frame, 3: alignment mark, 11: optical device, 12: carrier device, 13:
Imaging device, 20: central processing unit, 21: XYZ stage, 22: transport unit control device, 23: image processing device, 3
1: Stage control device, 33: Display monitor, 3
4: input device, 35: coordinate data storage device, 36: bonding data reading device, 37: CAD data reading device.

Claims (6)

[Claims] 1. A wire bonding inspection device for automatically inspecting a wire connection state of a semiconductor chip after wire bonding, comprising: an image pickup device; and the image pickup device positioned at a measurement reference point preset for the semiconductor chip. In the wire bonding inspecting apparatus, the positioning means, and the processing means for driving and controlling the imaging device and the positioning device to obtain image data at each measurement reference point and outputting information regarding the connection state based on the data. The processing means positions the image pickup device with respect to the semiconductor chip after wire bonding based on the CAD data of the semiconductor chip and wire bonding,
A wire bonding inspecting device, which obtains image data and sets the measurement reference point based on the image data and the CAD data. 2. A wire bonding inspection device for automatically inspecting a wire connection state of a semiconductor chip after wire bonding, comprising: an image pickup device; and the image pickup device positioned at a preset measurement reference point for the semiconductor chip. In the wire bonding inspecting apparatus, the positioning means, and the processing means for driving and controlling the imaging device and the positioning device to obtain image data at each measurement reference point and outputting information regarding the connection state based on the data. The processing means positions the image pickup device with respect to the semiconductor chip after wire bonding based on the bonding data of the wire bonding, obtains image data, and based on the image data and the bonding data, the measurement reference. Wire wire characterized by setting points Bonding inspection device. 3. The positioning means comprises a carrying means for holding and carrying the lead frame to which the semiconductor chip is wire-bonded, and the processing means comprises the CAD.
2. The wire bonding inspection apparatus according to claim 1, wherein drive control of the carrying means is performed based on information included in the data. 4. The positioning means comprises a carrying means for holding and carrying the lead frame to which the semiconductor chip is wire-bonded, and the processing means includes a carrying means of the carrying means based on information included in the bonding data. The wire bonding inspection device according to claim 2, wherein the wire bonding inspection device performs drive control. 5. The processing means positions the image pickup device with respect to the semiconductor chip after wire bonding based on at least alignment mark data included in the CAD data, obtains image data, and the image data and the The wire bonding inspection apparatus according to claim 1, wherein the measurement reference point is set based on at least the data of the alignment mark. 6. A storage means for storing each data including the data of the measurement reference points.
[5] The wire bonding apparatus as described in [5].