JPS59147206A - Object shape inspecting apparatus - Google Patents

Abstract

PURPOSE:To obtain automation and improvement in accuracy by an apparatus wherein an irradiation angle of a light beam is varied relative to the image picked-up surface, and three-dimensional address of the focused point is detected from a moving angle signal of the light beam and an X-Y address signal of an image pickup device. CONSTITUTION:A light irradiation angle of a light projector 7 for irradiating a light beam to an inspected object 6 is varied by a light projector driving unit 8 to a minute extent. With this, a contour map of the surface of the inspected object 6 is depicted in the form of bright lines and read by an image pickup device 9. Individual reading points are scanned by an image pickup device driver of a bright point position detecting circuit 10, and X, Y scanning clock pulses as well as binary-coded brightness signal pulses at that time are input to an object shape detecting circuit 11. Meanwhile, drive control clock pulses for driving the light projector 7 are input from the light projector driving unit 8 to the object shape detecting circuit 11. The position on Z-axis is determined from those data, and the detected position data and the content of an object shape reference data memory 12 are inspected in a comparative inspection circuit 13.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a non-contact object shape inspection device, and more particularly to a device that automatically inspects the three-dimensional shape of an object using an optical method.

(b) Background of the technology Conventionally, non-contact shape inspection of objects such as wire loops after wire bonding processing of integrated circuits etc. was generally performed by visual inspection using an optical microscope. There was a demand for the introduction of automatic testing for speed and accuracy.

(C) Prior art and problems In the inspection using the conventional optical microscope described above, in addition to problems such as low inspection efficiency and easy to be accompanied by human error, it is difficult to quantitatively understand the loop shape. The drawback was that it was difficult.

That is, the position in the height direction of the wire loop, which is curved and stretched with a height difference of about several hundred micrometers, is determined using an optical I.
This is because even if an attempt is made to measure with a precision of several tens of micrometers using an FI microscope, it is difficult to obtain sufficient measurement accuracy in the depth of focus direction of the optical system.

As described above, the conventional methods had problems that needed to be solved before testing could be automated.

(d) Object of the Invention The object of the present invention is to provide an apparatus capable of measuring the three-dimensional dimensions of an object, such as a wire loop, with high precision and automatically.

(e) Structure of the Invention The present invention provides a light projection drive device for changing the projection angle of the light beam with respect to the imaging surface in an object shape detection circuit device comprising a light beam projector, an imaging device, and a light spot position detection circuit; The movement angle signal of the light beam projection drive device and the X of the imaging device
- an object shape detection circuit that detects the three-dimensional address of the light spot from the Y address signal, and a memory device that stores object shape reference data as necessary; The comparison test circuit compares the difference in the comparison data with the tolerance value, and if necessary, the tolerance value is determined according to the respective ranges of the X and Y addresses of the imaging device. Characterized by changing values.

(f) Embodiments of the Invention Embodiments of the present invention will be described below with reference to the drawings, taking shape inspection of a wire loop in an integrated circuit as an example.

FIG. 1 is a diagram showing an example of the wiring state of wire loops in an integrated circuit package, in which
Between the third electrode 2 and the band electrode 4 on the IC chip 3, wires 51 having a diameter of about 20 to 30 μm are wired at a ratio of several to IO wires per side.

As shown in FIG. 2 (cross-sectional view), the wire 51 is automatically wired by a wire bonder so that its central portion forms a loop shape curved at a predetermined height from the bonding portions at both ends. Hereinafter, the wire 51 will be referred to as the wire loop 5.

However, in reality, wire loops 5 having various curved shapes as shown in FIG. 3 may exist.

In FIG. 3, (A) shows that the wire loop 5 is hanging down and I
If the end of the C chip 3 is contacted, (B) is ``If the height of the wire loop 5 is abnormally large, (C)
The above is a case where the wire loop 5 is wired with an insufficient height, resulting in defects such as noise generation, the curved shape of the wire loop 5 being crushed when the lid is attached to the package, and other adjacent wires being Defects such as short circuit with the loop, I
There is a possibility that defects such as short circuit with the wiring pattern formed on the C chip 3 may occur.

For the above reasons, it is necessary to inspect the shape of the wire loop 5 after it is formed.

FIG. 4 is a functional block diagram of the shape inspection apparatus according to the present invention, in which a light beam is projected from a light beam projector 7 onto an object to be inspected 6 (for example, the wire loop 5 on the package 1).

The beam projector 7 is configured to slightly change the beam projection angle with respect to the object to be inspected 6 by a beam projection drive device 8 . As a result, the position level of the projected light beam on the object to be inspected 6 changes slightly. That is, a contour map of the surface of the object to be inspected 6 is drawn as bright lines corresponding to each position level.

The contour map at each position level is read by the imaging device 9. As the imaging device 9, a device using a solid-state imaging device such as a CCD is suitable, for example.

Each reading point on the imaging device 9 is scanned by the imaging device driver of the light spot position detection circuit 10, and the X scanning clock pulse, Y scanning clock pulse, and the binarized luminance signal pulse at that time are sent to the object shape detection circuit 11. is input.

On the other hand, a drive control clock pulse for driving the beam projector 7 is inputted to the object shape detection circuit 11 from the beam projector driving device W8.

As shown in FIG. 5, each of these clock pulses is counted by an X address counter, an Three-dimensional position data is determined, and only the position data for which the binarized luminance data is on is stored in the memory (built in the object shape detection circuit 11).

In other words, by selecting data at an arbitrary Z address from the above data and plotting it, the contour map can be drawn. For example, if the above position data is converted to a polar coordinate system with the X-Y plane as the reference plane, and data at an arbitrary azimuth angle is selected and plotted, it is possible to cut the object 6 to be inspected on a plane parallel to the Z direction. The cross-sectional profile of the case is obtained.

By the way, in the shape inspection of the wire loop,
The deviation of the wire loop from the predetermined position in the χ-■ plane is relatively small. As items to be inspected, it is especially important to know the above-mentioned cross-sectional profile and Z-direction position coordinates. , it becomes possible to perform inspection more accurately and easily than before.

Alternatively, as shown in FIG. 4, an object shape reference data memory 12 and a comparison inspection circuit 13 are installed, and the detected position data stored in the object shape detection circuit 11 and the object shape 1
Then, the reference data of the reference data memo January 2 may be graphically displayed and compared (Fig. 6), or the comparison test circuit 13 may be used to determine the difference between both data and this may be output in a graphical display, etc. Furthermore, a deviation tolerance value (±ΔZo) is set in the comparative inspection circuit 13 corresponding to each reference data, and the magnitude of the difference ΔZ between the detected position data and the reference data and the ΔZO is verified. It is also possible to automatically determine whether the shape is good or bad based on the results (FIG. 7).

Incidentally, in order to detect shape defects as shown in FIGS. 3A and 3C, it is necessary to carefully examine the shape of the wire loop in the vicinity of the lead electrode 2 and pad electrode 4. For this reason, as shown in FIG. 8, by setting the deviation tolerance value Δzo to a small value ΔZos in the vicinity of both electrodes, automatic shape inspection for this purpose becomes possible.

In addition, in FIG. 8, the deviation tolerance value ΔZosl is different in the vicinity of the lead electrode and in the vicinity of the pad electrode.
, ΔZO511 are set.

FIG. 9 shows an example of the configuration of an optical system in an object shape inspection apparatus according to the present invention.

The lens 1 is arranged so that the light beam emitted from the light source 14 such as a laser is focused on the object to be inspected 6 such as the wire loop.
Set 5. The light beam is transmitted through a reflecting mirror 16 and a rotational drive mechanism 17.
The light beam □ is reflected in the direction of the object to be inspected 6 by the projector. In this case, the rotational drive mechanism 17 is driven by a control signal from the light beam projector drive device 8, and rotates the reflecting mirror so as to scan the light beam in the Z-axis direction (in other words, perpendicular to the surface of the object to be inspected). Rotate 16.

Although it is necessary to scan the reflected light from the reflecting mirror 16 in a direction parallel to the -Y plane on the figure using another drive mechanism, it is easy to scan the reflected light from the cylindrical lens 1 as shown in FIG.
8 may be used to project in a fan-shaped beam.

As described above, the light beam is moved in the Z-axis direction on the object to be inspected 6 at intervals of, for example, 20 μm, and at each step of this interval, the imaging device 9 performs reading in the X-Y plane. .

In the case of the wire loop inspection, usually 10 to 20
Reading is performed in steps, and shape data in a height range of about 300 μm is read. FIG. 11 is a schematic diagram showing this situation, and in FIG. 11 (B), a,
b, c, . . . indicate steps in the Z-axis direction, and in each step, light spots a1, C2, bl, b2, C1, C2, . . . are generated when the wire loop is irradiated with light.
The position image on the X-Y plane is as shown in FIG.

(g) Effects of the Invention According to the present invention, it is possible to provide a device that can inspect the three-dimensional shape of an object quickly, with high precision, and automatically.

[Brief explanation of drawings]

1 to 3 are diagrams showing wiring positions of wire loops in an integrated circuit and examples of their shapes; FIGS. 4 and 5 are functional block diagrams of the object shape inspection device according to the present invention;
8 to 8 are diagrams for explaining an example of a method of comparing read data and reference data in the object shape inspection device according to the present invention, and FIGS. FIG. 3 is a diagram for explaining the configuration of an optical system in the shape inspection device. In the figure, 1 is an integrated circuit package, 2 is a lead electrode,
3 is an IC chip, 4 is a pad electrode, 5 is a wire loop, 6 is an object to be inspected, 7 is a light beam projector, 8 is a light beam projector driving device, 9 is an imaging device, IO is a light to point position detection circuit, 1
1 is an object shape detection circuit, 12 is an object shape reference data memory, 13 is a comparison inspection circuit, 14 is a light source such as a laser, 15
is a lens, 16 is a reflecting mirror, 17 is a rotary drive mechanism, 18 is a cylindrical lens, Fig. j Fig. 2 and A) and b
) (C) 3rd-
Figure 0 Qin 4 Mouth 1 〆Collection 7shij War q Figure Not 1 (ν] (A) (Bn 2 1,000-

Claims (4)

[Claims] (1) In an object shape inspection device consisting of a light beam projector, an imaging device, and a light spot position detection circuit, a light beam projector drive device for changing the projection angle of the light beam with respect to the imaging surface, and a drive device for the light beam projection type drive device are provided. Movement angle signal and X-Y of the imaging device
An object shape inspection device comprising an object shape detection circuit that detects a three-dimensional address of a light spot from an address signal. (2) a memory device storing object shape reference data;
2. The object shape inspection apparatus according to claim 1, further comprising a comparison inspection circuit for comparing data from said object shape detection circuit with data in said memory device. (3) The object shape inspection device according to claim 2, wherein the comparison inspection circuit has a function of comparing the difference in comparison data with a tolerance value. (4) The object shape inspection device according to claim 3, wherein the allowable value is changed depending on the respective ranges of the X address and Y address of the imaging device.