JPH0732188B2 - Semiconductor device inspection equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a semiconductor device inspection apparatus that performs a visual inspection of a wire bonding state of a semiconductor device that has completed a wire bonding process such as ball bonding or wedge bonding. is there.

[Prior art]

Conventionally, the inspection of the wire bonding state has been manually performed by visual inspection by an operator. Items to be inspected include, in the case of ball bonding, no wire, wire break, misbond (bond at wrong place), wire height, wire curl (excessive bend), lift bond (lift of bond part), pad , The bond position with respect to the lead, the size or shape of the ball or stitch, and the like.

Further, as disclosed in JP-A-61-148828, an attempt has been made to inspect the amount of deformation of the wire in the height direction by using a camera equipped with a lens having a shallow depth of focus and moving the camera up and down.

[Problems to be Solved by the Invention]

However, in the conventional visual inspection, the inspection efficiency is low because the inspection results vary and the accuracy is low and it takes time.

In addition, in the inspection using a camera, it takes time to move the camera in the vertical direction, and the lens has a high magnification and a narrow field of view. Therefore, in order to cover a wide area around the IC chip of the semiconductor device, pads and leads are required. It was necessary to move the camera horizontally every time, which took time and the inspection efficiency was low.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor device inspection apparatus which solves the above conventional problems, facilitates automation of appearance inspection, and improves inspection accuracy and inspection efficiency.

[Means for Solving the Problems]

As a means for solving the above problems, the present invention stores and supplies a semiconductor device after wire bonding in a semiconductor device inspection device that performs an appearance inspection of a semiconductor device after wire bonding at an inspection stage. A loading device, a transfer device that transfers the semiconductor device supplied by the loading device and discharges the semiconductor device through the inspection stage, and an unloading device that receives the semiconductor device discharged by the transfer device and accommodates the semiconductor device. The inspection stage has a field of view including the IC chip of the semiconductor device and the entire periphery thereof, and a plurality of low-magnification image pickup devices whose image pickup central axes coincide with the inspection point and one pad or lead and a field of view including the periphery thereof. An image pickup device of a semiconductor device including a magnification image pickup device, and digitally processing an image pickup signal obtained by the image pickup device, An image processing device that determines the quality of the bonding state by comparing with standard data stored in the memory circuit, and a marking device that attaches a determination mark for distinguishing the quality of the semiconductor device based on the determination signal of the image processing device, It is intended to provide an inspection device for a semiconductor device, which is characterized by including:

[Action]

In the present invention, the field of view of each low-magnification imaging device is
The entire bonding state of the IC chip and its surroundings can be seen at a time, and the positional deviation of the IC chip and the shape and dimensions of the wire loop are three-dimensionally inspected without moving the image pickup device vertically or horizontally. Inspect for defects by comparing with standard data already stored.

Further, the field of view of the high-magnification image pickup device is such that one pad or lead of the semiconductor device and the bonding state around it can be seen, and mainly the ball, stitch position, shape,
Inspect the dimensions. This field of view moves for each pad and lead, but since the position of each pad is calculated and stored in the memory circuit based on the amount of displacement of the IC chip already obtained with the low-magnification imaging device, Also, it is not necessary to detect the pad position again at the time of high-magnification imaging, and the calculated position can be quickly moved to the target.

〔Example〕

 Embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, a supply magazine 2 for accommodating a semiconductor device such as a lead frame which has completed a wire bonding process on a base frame 1 of a main body of an inspection apparatus, a supply elevator 3 for elevating and lowering the supply magazine 2, an external view The inspection stage 4 for inspecting, the extrusion device 5 for extruding and supplying the semiconductor devices in the supply magazine 2 one by one to the inspection stage 4, the semiconductor device 6 supplied to the inspection stage 4 for the low magnification inspection point 7, There are provided a transfer device 10 for intermittently transferring through a magnification inspection point 8, a marking point 9, a storage magazine 11 for storing a semiconductor device which has been inspected and marked, and a storage elevator 12 for moving the storage magazine 11 up and down. ing. The transfer device 10 may move a plurality of semiconductor devices at the same time in one set, or may use a plurality of sets to move simultaneously or independently.

An image pickup device for picking up an image of a semiconductor device includes a plurality of low-magnification image pickup devices 14 provided on an XY table 13 and a high-magnification image pickup device 16 provided on an XY table 15. An image of a predetermined portion of the semiconductor device 6 is picked up at the inspection point 8. Reference numeral 17 denotes a monitor that displays the captured image.

Reference numeral 18 denotes a marking device for marking a defective portion of the semiconductor device, which has a defective inspection result, at the marking point 9 according to the inspection result.

The field of view of each low-magnification imager 14 is as shown at 19 in FIG.
The field of view is such that the entire bonding state of one IC chip 20 and its periphery can be seen at once, and mainly the positional deviation of the IC chip 20 and the shape and size of the wire loop are inspected.

When the IC chip 20 is particularly large like a VLSI, it is divided into a plurality of fields of view and moved by the XY table 13 to inspect the whole.

The field of view of the high-magnification image pickup device 16 is such that one pad 22 (or lead) and the bonding state around it can be seen as shown by 21 in FIG. 3, and mainly the ball, stitch position, shape and size are inspected. . The field of view 21 moves for each pad and lead, but since the position of each pad is calculated based on the displacement amount of the IC chip 20 already obtained by the low-magnification imaging device 14 and stored in the memory circuit, the field of view 21 It is not necessary to detect the pad position again at the time of high-magnification imaging even when the movement is performed, and the movement can be performed quickly with the calculated position as a target.

An example of the low-magnification imaging device 14 is shown in FIGS. 4, 5, and 6.

The low-magnification image pickup device 14 includes lens systems 23A, 23B, 23C and a light-receiving surface 24.
A, 24B, 24C, optical / electrical converter 25A, 25B, 25C, lens barrel 26A, 26B,
Imaging unit 27A, 27B, 27 consisting of 26C, diaphragms 45A, 45B, 45C
The imaging center axes 28A, 28B, 28C, which are provided with C and connect the center of each light receiving surface and the center of the lens, coincide with the low-magnification inspection point 7 on the IC chip 20, and as shown in FIG. Imaging center axis 2 in the opposite direction (180 ° direction) to axes 28A and 28C
8B is perpendicular to the imaging center axes 28A and 28C. The lens surface of each lens system 23A, 23B, 23C (the surface perpendicular to the principal axis of the lens) and the light-receiving surfaces 24A, 24B, 24C are all held parallel to the surface of the IC chip 20. That is, the plane 42,4
3,44 are parallel.

When the image pickup units 27A, 27B, and 27C are arranged and imaged as described above, the image pickup central axes 28A, 28B, and 28C are tilted with respect to the surface of the IC chip 20, but the light receiving surfaces 24A, 24B, and 24C are formed. The image formed is in focus over the entire field of view of FIG. 2 and, moreover, as if the image was taken from directly above, for example, the IC chip 20 is imaged in a square shape without distortion.

However, since the images are taken from an oblique direction, images with different heights are imaged with different shapes and dimensions for each imaging unit 27A, 27B, 27C, and the imaging signals of at least two of these imaging units are digital. It is possible to calculate the three-dimensional size and shape of each part by synthesizing and composing.

When the image pickup of the IC chip 20 as shown in FIG. 2 is performed by the three image pickup units 27A, 27B, and 27C, for example, if the bonding portion 29 is in a normal state, the image pickup units in FIG. , (B), (c) are imaged, and by calculating using the digital amount of the position of each part obtained from two of these images, the three-dimensional shape of an arbitrary point P, Q etc. of the wire 30 can be obtained. It is possible to find the desired position. 31 is the lead, 32
Is a ball and 33 is a stitch.

Further, for example, when the bonding portion 29 'is in a normal state, the image pickup unit 27A takes an image as shown in FIG. 8A, and the image pickup unit 27B takes an image as shown in FIG. The three-dimensional position of an arbitrary point of the wire 30 can be obtained by digitally processing each position of 30 and performing a composite operation.

The low-magnification image pickup device is compared with the standard data that has already been stored by comparing the thus obtained data relating to the actual object.
Due to 14, the position of the IC chip 20 is misaligned, the wires in each part are missing, the wire is broken, the misbond (bonds to other locations), the wire height is inappropriate, the wire curl (lateral displacement, contact with the next wire), lift Bond (ball 32 or stitch 33
It is possible to inspect whether or not there is a defect such as that the pad floats up from the pad 22 or the lead 31 and is not in contact therewith.

At this time, it is not necessary to inspect each wire, and several wires may be put together into several blocks or divided into several blocks.
Alternatively, the whole can be inspected by digital processing all at once. Therefore, the inspection time becomes extremely short,
In addition, since the allowable limit is digitized, there is no variation in inspection and accuracy is improved.

The number of imaging units may be only two. The directions of the imaging center axes of the two or three sets of imaging units can be arbitrarily selected. For example, in FIGS. 4 to 6, only the image pickup unit 27A may be vertical.

In addition to the image pickup unit shown in FIGS. 4 to 6, another recognition unit may be provided vertically in the center.

In the high-magnification image pickup device 16, pattern recognition is performed using an image enlarged in a narrow field of view as shown in FIG. 3, and a ball 32 (or stitch 3) obtained by digital processing is obtained.
3) The position deviation with respect to the pad 22 (or the lead 31), the shape and the size of the ball 32 (or the stitch 33) can be compared with standard data stored in advance to inspect for the presence or absence of a defect.

In this case, it is not necessary to inspect all the bonding portions, and a certain number of sampling inspections may be performed.
Since it is not necessary to inspect the position of the pad again, the time can be omitted, the inspection by the high-magnification imaging can be performed in a short time commensurate with the inspection by the low-magnification imaging, and the overall inspection efficiency is improved. Further, since the allowable limit is digitized, there is no variation in the inspection and the accuracy is improved.

Since the lens system of the high-magnification image pickup device 16 has a high magnification, the depth of focus is shallow, and it is necessary to focus on each of the slight height differences between the surface of the pad 22 and the surface of the lead 31. I won't. This focusing operation is performed by adjusting the lens system in the device, by moving the device up and down, and by adjusting the focus of both planes by inserting and removing the light-transmitting body 34 such as thin glass under the lens system. You may do it.

The marking device 18 attaches a defect mark in the vicinity of the defective IC chip in accordance with an inspection signal from the low-magnification image pickup device 14 or the high-magnification image pickup device 16 to serve as a mark for rejecting defective products in a subsequent process.

FIG. 9 is an explanatory diagram of a signal system path, 35 is a camera control unit, 36 is a pattern recognition unit as an image processing device, 37 is an interface control system, 38 is a CPU, 39
Is a memory circuit, 40 is a stage driver, and 41 is another driver.

The memory circuit 39 stores standard data regarding each inspection item, or a calculation program for calculating the three-dimensional position by combining plane position data from two image pickup units.

In the camera control unit 35, the entire field of view or the field of view is divided into a plurality of blocks to scan a frame once or several times to output a digital image pickup signal, and in the pattern recognition unit 36, the input signal And a standard data signal based on standard data from the memory circuit 39 are compared to determine whether the input data signal is normal or abnormal.If the input data signal is defective, a signal is sent to the marking device 18 to mark near the corresponding IC. Attach.

In addition to the imaging screen as the inspection information, the monitor 17 can display the inspection numerical value, defect location, defect analysis, etc. in real time, so that the situation can be immediately fed back to the bonding machine and actions such as setting of bonding conditions performed. Can be done promptly.

In addition, by collecting inspection data, it is possible to promptly deal with a defect occurrence point in the previous process, and improve the production yield.

FIG. 10 and FIG. 11 show an example of the illuminator at the low magnification inspection point 7. An illumination lamp 46 having an annular light source is provided so as to surround the IC chip 20 at the low-magnification inspection point 7 and at a low position close to the inspection surface. By being illuminated from the surroundings and from a low position, the three-dimensional shape of the bonding wire 30 can be clearly imaged without error.

〔The invention's effect〕

According to the present invention, the low-magnification imaging device provides a wide field of view,
Due to the deep depth of focus, it is easy to focus three-dimensionally in a wide field of view, and it is possible to quickly inspect without the need to move the image pickup device vertically or horizontally. Also, the high-magnification image pickup device scans by the low-magnification image pickup device Part is omitted, the time is shortened, the overall inspection efficiency and inspection accuracy are improved, and the appearance inspection of the banding part of the semiconductor device is easily automated, and the allowable range is quantified and there is no variation in inspection. It has an extremely great effect in practical use.

[Brief description of drawings]

The drawings relate to an embodiment of the present invention. FIG. 1 is an overall perspective view, FIG. 2 is a field of view of a low-magnification imager, FIG. 3 is a field of view of a high-magnification imager, and FIG. 4 is a low-magnification imager. 5 is a cross-sectional front view of a vertical plane parallel to the transfer direction of the semiconductor device 6 passing through the low-magnification inspection point 7 of FIG. 5, FIG. 5 is a cross-sectional side view of the II line, FIG. (A), (b),
FIG. 8 (a) is an explanatory view of how an image looks when one bonding portion is imaged by different imaging units, FIG. 8 (a),
(B) is an explanatory view of how an image looks when another one of the bonding parts is picked up by a different imaging unit, FIG. 9 is an explanatory view of a signal system path, and FIG. 10 is a plan view of an embodiment of a lighting fixture. , 11th
The figure is a front view taken along the line II-II. DESCRIPTION OF SYMBOLS 1 ... Base frame, 2 ... Supply magazine, 3 ... Supply elevator, 4 ... Inspection stage, 5 ... Extrusion device, 6
... Semiconductor device, 7 ... Low magnification inspection point, 8 ... High magnification inspection point,
9 ... Marking point, 10 ... Transfer device, 11 ... Storage magazine, 12 ... Storage elevator, 13 ... XY table, 14 ... Low magnification image pickup device, 15 ... XY table, 16 ... High magnification image pickup device, 17
… Monitor, 18… Marking device, 19… View, 20… IC chip, 21… View, 22… Pad, 23A, 23B, 23C… Lens system, 24A, 24B, 24C… Light receiving surface, 25A, 25B, 25C… Light・ Electrical converter, 26A, 26B, 26C ... Lens barrel, 27A, 27B, 27C ... Imaging unit,
28A, 28B, 28C ... Imaging center axis, 29, 29 '... Bonding part,
30 ... wire, 31 ... lead, 32 ... ball, 33 ... stitch,
34 ... Translucent body, 35 ... Camera control unit, 36 ... Pattern recognition unit, 37 ... Interface control system, 38
… CPU, 39… Memory circuit, 40… Stage driver, 41…
Other drivers, 42, 43, 44 ... Plane, 45A, 45B, 45C ... Aperture, 4
6… Lighting.

Front Page Continued (72) Inventor Tushar Kotohari, California, USA 93063 North Voyageur Avenue, 1650 View Engineering Incorporated (72) Inventor Valerie Riudusius, California, USA 93063 Simi Valley, North Voyager Avenue 1650 View Engineering Incorporated (72) Inventor Taka Ueato 3-5-1 Sakaemachi, Hamura-cho, Nishitama-gun, Tokyo Kaiji Electric Co., Ltd. (56) Reference JP-A-57- 155743 (JP, A) JP 61-148828 (JP, A)

Claims (1)

[Claims] 1. A semiconductor device inspecting apparatus for performing visual inspection of a semiconductor device after wire bonding at an inspection stage, wherein the semiconductor device after wire bonding is stored.
A loading device for supplying, a transfer device for transferring the semiconductor device supplied by the loading device and discharging the semiconductor device through the inspection stage, and an unloading device for receiving the semiconductor device discharged by the transfer device and accommodating the semiconductor device. A plurality of low-magnification image pickup devices having a field of view including the IC chip of the semiconductor device provided on the inspection stage and the entire periphery thereof, and a plurality of low-magnification image pickup devices whose image pickup central axes coincide with the inspection point and one pad or lead and its periphery An image pickup device of a semiconductor device including a high-magnification image pickup device having a field of view, and an image pickup signal obtained by the image pickup device are digitally processed, and compared with standard data stored in a memory circuit in advance to determine a bonding state. An image processing apparatus that determines pass / fail, and a mark that marks a semiconductor device based on a determination signal of the image processing apparatus. Inspection apparatus for a semiconductor device characterized by comprising: a ring device.