JPH0536794A - Method and apparatus for measuring wire-shaped object - Google Patents

Abstract

(57) [Abstract] [Purpose] A wire shape measuring method and apparatus suitable for inspecting a bonding wire that connects a semiconductor chip and a lead frame, and to accurately and quickly measure the wire shape. The purpose is to do. A method for measuring a wire-shaped object 1 having a substantially circular cross section and a total reflection surface for totally reflecting irradiated light, wherein light for linearly scanning a light beam LB on the surface of the wire-shaped object 1 The beam scanning step and the reflected light detection means 2 for covering the wire-shaped object 1 with the reflected light RL from the surface of the wire-shaped object 1.
And a three-dimensional shape measuring step of measuring the three-dimensional shape of the wire-shaped object 1 based on the output signals of the plurality of optical sensor cells 21. A method for measuring a wire-shaped object, comprising:

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire shape measuring method and apparatus, and more particularly to a bonding wire (hereinafter, also simply referred to as a wire) for connecting a semiconductor chip (IC chip) and a lead frame (package). The present invention relates to a method for measuring a wire-shaped object suitable for inspection and an apparatus therefor.

In recent years, the number of wires connecting between the IC chip and the package has been increasing with the trend toward higher density and smaller size of the IC chip. Specifically, for example,
It is not uncommon for one IC chip to use more than 100 bonding wires. In such an IC chip using a large number of wires, the wire pitch (distance between adjacent bonding wires) is 0.2.
Since the width is extremely narrow, such as about mm, the occurrence of manufacturing errors such as short-circuiting between adjacent wires or contact with a substrate is increasing. Therefore, it is required to accurately measure the three-dimensional shape of a bonding wire in an IC chip having a large number of bonding wires in a short time.

[0003]

2. Description of the Related Art Conventionally, for example, when a manufacturing error such as a short circuit between adjacent wires or a contact between a wire and a substrate, a defective portion is manually found by observing the vicinity of a wire connecting portion with a microscope. Such a method was common. However, the discovery of manufacturing errors by such human observation is
Since it is visual, there is a limit in terms of inspection accuracy and inspection speed, and since it is merely observing the vicinity of the wire connection part in a plane, for example, the horizontal direction (X,
Abnormal proximity in the Y direction (for example, the pitch is too narrow) can be determined without any problem, but abnormal proximity in the vertical direction (Z direction) between the wire and the substrate (or semiconductor chip) located below it. This could not be determined.

FIG. 15 is a view showing a state of a bonding wire connecting a semiconductor chip and a lead frame,
The figure (a) shows a normal bonding wire, and the figure (b).
~ (D) shows a defective bonding wire. Figure 1
5 (a) to (d), reference numerals 401a to 401d are bonding wires, 402 and 403 are lead frames, and 404 is a semiconductor chip (substrate).

In contrast to the normal bonding wire 401a shown in FIG. 15 (a), the bonding wires 401b to 401d shown in FIGS. 15 (b) to 15 (d) are "deflection", "over tension" and " It is not desirable because it is in the state of "hanging down". FIG. 16 is a diagram for explaining a problem in the conventional technique for measuring a wire-shaped object. Reference numerals 402 and 403 are lead frames, 404 is a semiconductor chip (substrate), 4
Reference numerals 11 and 412 denote bonding wires. As shown in the figure, when a person visually inspects a bonding wire using a microscope, for example, two adjacent bonding wires 411 and 412 are observed as two lines, and therefore XY A two-dimensional inspection such as contact on a plane can be performed, but an inspection in the height direction (Z-axis direction) cannot be performed. Specifically, for example, in the height direction of the bonding wire 412, the semiconductor chip 404
When the corner is abnormally close to the corner, that is, when the gap dd is extremely small, the defect could not be detected by visual inspection.

[0006]

As described above, the visual inspection of the bonding wire cannot perform the inspection in the height direction, so that various methods capable of measuring a three-dimensional shape have been conventionally proposed. ing. FIG. 17 is a diagram showing an example of a conventional method for measuring a wire-shaped object.
(c) shows a method for detecting the three-dimensional shape of the bonding wire.

FIG. 17 (a) shows an example of a light projecting method, in which light is sequentially emitted from light sources 304a to 304e, the images thereof are taken by a television camera 303, and the images are combined to form a bonding wire. It measures the three-dimensional shape of 301. In addition, FIG. 17 (b) shows an example of a stereoscopic method. The illuminated bonding wire 301 is photographed by two TV cameras 351 and 352, and the images thereof are combined to form a three-dimensional shape of the bonding wire 301. Is measured. Further, FIG. 17C shows an example of the focusing method, in which the degree of blurring of the image captured by the lens 306 having a shallow depth of focus is identified and the three-dimensional shape of the bonding wire 301 is measured.

However, these conventional wire-shaped object measuring methods require a long time to measure the three-dimensional shape of the bonding wire, for example, and some of them are not sufficient in terms of measurement accuracy. The present invention has been made in view of the problems of the above-described conventional technique for measuring a wire-shaped object, and an object thereof is to accurately measure a wire-shaped object in a short time.

[0009]

According to the first aspect of the present invention, there is provided a method for measuring a wire-shaped object 1, 11 having a substantially circular cross section and a total reflection surface for totally reflecting the irradiated light. There
The light beam scanning step of linearly scanning the surface of the wire-shaped object 1,11 with the light beam LB, and the reflected light RL from the surface of the wire-shaped object 1,11 is reflected light that covers the wire-shaped object 1,11. Detection means
A reflected light detection step of detecting with a plurality of optical sensor cells 21 arranged on the inner wall 2a of 2,20, and a tertiary measuring the three-dimensional shape of the wire-shaped objects 1, 11 based on the output signals of the plurality of optical sensor cells 21 An original shape measuring step is provided.

According to the second aspect of the present invention, there is provided a measuring device for measuring wire-shaped objects 1 and 11, wherein the light-beam scanning means 3 for linearly scanning the surface of the wire-shaped objects 1 and 11 with the light beam LB. 30 and
Reflected light detecting means 2 provided so as to cover the wire-shaped objects 1 and 11, and a plurality of light receiving surfaces are attached to the inner wall 2a of the reflected light detecting means 2 so that the light receiving surface faces the inside of the reflected light detecting means 2. Optical sensor cells 21 each having an address indicating a position on the inner wall 2a of the reflected light detecting means 2 and the reflected light RL from the surface of the wire-shaped object 2a. Calculation means 5 for calculating the direction of the bright line BL projected by the reflected light RL onto the inner wall 2a of the reflected light detecting means 2 based on the output signals of the plurality of light sensor cells 21 receiving the light and the addresses of the light sensor cells 21. , 51
And a wire shape measuring device comprising reconstructing means 6 and 52 for reconstructing the three-dimensional shape of the wire shaped objects 1 and 11 based on the calculation results of the calculating means 5 and 51. Provided.

[0011]

According to the wire-shaped object measuring method of the present invention, first, in the light beam scanning step, the surface of the wire-shaped objects 1 and 11 is linearly scanned with the light beam LB. Next, in the reflected light detection stage, the reflected light RL from the surface of the wire-shaped objects 1 and 11 is detected.
Is the inner wall of the reflected light detection means 2, 20 that covers the wire-shaped objects 1, 11.
It is detected by the plurality of photosensor cells 21 arranged in 2a. Furthermore, in the three-dimensional shape measuring step, the three-dimensional shapes of the wire-shaped objects 1 and 11 are measured based on the output signals of the plurality of photosensor cells 21.

According to the wire-shaped object measuring apparatus of the present invention, the light beam scanning means 3, 30 linearly scans the surface of the wire-shaped objects 1, 11 with the light beam LB. Reflected light detecting means 2
Is provided so as to cover the wire-shaped objects 1 and 11, and its inner wall
A plurality of optical sensor cells 21 are attached to 2a so that the light receiving surface faces the inside of the reflected light detecting means 2. An address indicating the position on the inner wall 2a of the reflected light detecting means 2 is given to each of the plurality of photosensor cells 21. Further, the calculation means 5, 51, the reflected light RL reflected light detection means based on the output signal of the plurality of photosensor cells 21 that received the reflected light RL from the surface of the wire-shaped object 2a and the address of the photosensor cells 21. The direction of the bright line BL projected on the inner wall 2a of 2 is calculated. Then, the reconstructing means 6, 52 reconstructs the three-dimensional shape of the wire shaped objects 1, 11 based on the calculation results of the calculating means 5, 51.

Here, the wire-shaped object (eg, bonding wire) has a substantially circular cross section and a total reflection surface for totally reflecting the irradiated light beam. As mentioned above,
According to the wire shape measuring method and the apparatus thereof according to the present invention, the surface of the wire shape is linearly scanned with a light beam,
The reflected light from the surface of the wire-shaped object is detected by a plurality of photosensor cells arranged on the inner wall of the reflected light detection means, and the shape of the wire is measured based on the signals from the photosensor cells, thereby obtaining the wire shape. It is possible to measure an object accurately and in a short time.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method and apparatus for measuring a wire-shaped object according to the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a wire-shaped object measuring apparatus according to the present invention. In FIG. 1, reference numeral 1 is a bonding wire (wire-shaped object), and 2 is a reflected light RL or a bright line BL. Dome (reflected light detection means), 3 is a light beam scanning means,
Reference numeral 4 is an amplifier, 5 is a calculation means, and 6 is a reconstruction means. Here, the bonding wire 1 is a semiconductor chip (1
Wire for connecting (0) and lead frame (40),
Generally, it has a substantially circular cross section and a total reflection surface that totally reflects the irradiated light beam LB.

As shown in FIG. 1, the light beam scanning means 3 includes a beam generation source 31 and a lens group 3 for expanding the beam diameter.
2, a vibrating mirror 33 that linearly scans a light beam, a focusing lens 34, and the like are provided. The light beam LB is linearly scanned on the surface of the wire (bonding wire) 1 by the light beam scanning means 3. That is, the scanning line SL crosses the wire 1.

The dome 2 has a hemispherical shape and is arranged so as to cover the wire 1. A plurality of optical sensor cells 21 are arranged on the inner wall 2a of the dome 2, and the light receiving surface of the optical sensor cells 21 faces the inside of the dome 2 so that the reflected light (RL) from the wire 1 can be detected. Further, a slit 2b is provided at the apex (pole) of the dome 2 so that the light beam LB linearly scanned by the light beam scanning means 3 can pass into the dome 2. Here, an address indicating the position on the inner wall 2a of the dome 2 is given to each photosensor cell 21. Inner wall 2a of dome 2
The outputs of the plurality of photosensor cells 21 arranged at are respectively supplied to the calculating means 5 via the amplifier 4, and the output of the calculating means 5 is further supplied to the reconstructing means 6.

The calculation means 5 is a bright line projected on the inner wall 2a of the dome 2 based on the output signals of the plurality of photosensor cells 21 that have received the reflected light (RL) from the surface of the wire 1 and the addresses of the photosensor cells. The direction of (BL) is calculated, and the reconstructing unit 6 reconstructs the three-dimensional shape of the wire 1 based on the calculation result of the calculating unit 5.
That is, a large number of optical sensor cells 21 detect bright lines (the curvature and the forming position of which change depending on the height and inclination of the wire 1) formed on the inner wall 2a of the dome 2 by the reflected light (RL) from the surface of the wire 1. The detected result is the bright line (BL)
Position and the degree of bending of the bright line are calculated, and the three-dimensional shape of the wire is reconstructed based on these calculation results.

Here, the reflected light detecting means 2 is formed as a hemispherical dome, but it may be formed as a half of a polyhedron. In this case, it is preferable that the number of faces of the polyhedron is large, and in particular, a hemispherical dome as in the present embodiment has an optimum shape. Furthermore, it is not necessary for the reflected light detection means 2 to be composed of a closed surface,
For example, the semiconductor chip, the bonding wire, and the like located inside can be configured in a mesh shape so that they can be observed from the outside.

FIG. 2 is a diagram for explaining the characteristics of the reflected light from the wire-shaped object which is the principle of the present invention, and FIG. 3 is the internal wall of the dome by the reflected light from the wire-shaped object which is the principle of the present invention. It is a figure for demonstrating the bright line drawn. Figure 2
3, reference numeral 11 indicates a wire-shaped object (bonding wire 1), 10 indicates an axial direction of the wire-shaped object, and 12 and 13 indicate surfaces through which the reflected light RL passes.

First, as shown in FIG. 2A, when the light beam LB is scanned at right angles to the axis 10 of the wire-shaped object 11, that is, the scanning line SL is directed to the axis 10 of the wire-shaped object 11. When orthogonal, all the reflected light RL reflected on the surface of the wire-shaped object 11 passes through the same plane 12 orthogonal to the axis 10,
A bright line (BL) of "almost straight line along the direction of the scanning line SL" is drawn on the inner wall 2a of the dome 2 by 12. On the other hand, as shown in FIG. 2B, when the light beam LB is obliquely scanned with respect to the axis 10 of the wire-shaped object 11 at an arbitrary angle θ, that is, the scanning line SL is When crossing axis 10 diagonally,
All the reflected light RL reflected on the surface of the wire-shaped object 11 passes through the same curved surface 13 having a curvature defined by the angle θ, not the above-mentioned plane 12, and the curved plane 13 causes the inner wall 2a of the dome 2 to be reflected. A bright line (BL) having “a degree of bending and a drawing position according to the angle θ” is drawn at (see FIG. 3). Here, the angle θ between the light beam LB and the axis 10 of the wire-shaped object 11 is
The angle must be larger than 45 degrees, and when the angle θ is smaller than 45 degrees, the light reflected by the surface of the wire-shaped object 11 does not reach the inner wall 2a of the dome 2 located above. It will be.

In this way, the position of the bright line BL is obtained from the position (address) of the photosensor cell 21 that has detected the bright line BL, and the bending of the bright line BL is determined from the arrangement of the plurality of photosensor cells 21 that have detected the bright line BL. The condition (that is, the direction of each reflected light) is obtained, and further, if the diameter of the wire is known, the inclination of the wire is uniquely obtained from the bending condition of the bright line L 1.

FIG. 4 is a conceptual diagram showing how to reconstruct a three-dimensional shape of a wire-shaped object from the direction of reflected light, which is the principle of the present invention. As described above, the light beam BL (scan line
The inclination of the wire 1 at each site irradiated with (SL) can be obtained. As shown in FIG. 4, the calculation results of these minute parts should be connected to reconstruct the entire three-dimensional shape of the bonding wire 1. You can

FIG. 5 is a view showing a modified example of the wire-shaped object measuring apparatus shown in FIG. 1, and FIG. 6 is a view showing an inspection table inside a dome in the wire-shaped object measuring apparatus shown in FIG. As shown in FIGS. 5 and 6, below the dome 2, an inspection table 22 having the semiconductor chip 10 and the lead frame 40 (bonding wire 1) mounted thereon and movable in the XY directions is installed. There is. As described above, the slit 2b along the scanning direction of the light beam LB is formed at the apex (pole) of the dome 2, and the light beam LB passes through this slit 2b and the test site inside the dome 2 ( For example, the bonding wire 1) is irradiated. As a result, the scanning line SL is positioned at the test portion of the plurality of bonding wires 1, and the scanning line SL (light beam LB)
Is reflected on the surface of each bonding wire 1 to draw a bright line (BL) on the inner wall 2a of the dome 2. Here, as described above, a plurality of optical sensor cells 21 are attached to the inner wall 2a of the dome 2, and each optical sensor cell 21
The light-receiving surface of is exposed to the inside of the dome 2, and each photosensor cell 21 is provided with an address indicating the mounting position of the inner wall 2a of the dome 2. Also inspection table
The reference numeral 22 indicates not only the parallel movement in the XY plane but also the rotation (relative to the Z axis) in the XY plane (for example, rotation by 90 degrees). Wire 1 and slit 2b
The measurement may be performed with the light beam LB that is linearly scanned via.

By the way, when the dome 2 is likened to the northern hemisphere of the earth, the above address is the longitude φ (0 to 360) in the equatorial direction.
Degree) and the latitude λ (0 to 90 degrees) in the pole direction. For example, the total number of intersections on the 1st scale coordinate plane is 360 × 90 = 32,400, and the resolution is the same.
The optical sensor cell 21 has an address (φ0, λ0),
(φ1, λ0),…, (φ360, λ0), (φ360, λ1),…, (φ360,
It becomes 32,400 of λ90). Further, for example, the total number of intersections on the coordinate plane of the 10-degree scale is 36 × 9 = 324 points, and the resolution is also 10 degrees.
(φ0, λ0), (φ10, λ0),…, (φ360, λ0), (φ360, λ1
There are 324 of 0), ..., (φ360, λ90).

Each optical sensor cell 21 detects the reflected light (RL) from the measurement site of the bonding wire 1 with the scanning of the light beam, for example, with a resolution of 1 degree, and converts it into an electric signal. Output. The electric signal is amplified by the amplifiers 41 to 4n provided for each address of the optical sensor cell 21, and then sequentially input to the direction discriminating means (direction discriminating circuit: arithmetic means) 5. Based on the address change of the input signal, the direction discriminating means 5 determines the central position of the bright line (BL) formed on the inner wall 2a of the dome 2 by the reflected light (RL) (L / 2 when the length of the bright line is L / 2. The position indicated by the address), the direction of the bright line, and the degree of curvature (curvature) of the bright line are determined. Specifically, for example, when only φ (longitude) of the address changes, it is determined that the bright line is drawn in the direction of the predetermined longitude line passing through the pole, and only λ (latitude) changes. When it is, it is determined that the bright line is drawn in the direction of the equator or a predetermined latitude line parallel to the equator. Furthermore, when both φ (longitude) and λ (latitude) change, it is determined that an arbitrary curved line that is neither parallel to the longitude line nor the latitude line is drawn, and the curvature changes due to the address change. Judging from the size of.

The reconstructing means 6 (reconstructing circuit) determines a wire-shaped object (measurement object: bonding, for example, a bonding object) related to the bright line (BL) based on the above discrimination result, that is, the center position of the bright line (BL) and its direction and curvature. Reconstruct the three-dimensional shape of wire 1). The defect determination means (defect determination circuit) 7 refers to prestored reference three-dimensional data (reference data of the measurement target portion), determines whether or not the reconstructed data that has been sent is good, and determines the result. Is output to the output means 9 such as a display device or a printer. Here, reference numeral 8 is a control means, and the control means 9 controls the XY movement of the inspection table 22, and controls the operations of the direction determination means 5, the reconstruction means 6 and the defect determination circuit 7. It outputs various signals to perform.

FIG. 7 is a diagram showing reflected light when a wire-shaped object is arranged at a right angle to the light beam in the present invention, and FIG. 8 is an oblique view of the wire-shaped object with respect to the light beam in the present invention. It is a figure which shows the reflected light at the time of arrange | positioning.
It has already been described that when the surface of a cylinder having a substantially circular cross section (101a) is linearly scanned and irradiated with a light beam, all the reflected light from the surface passes through the same plane orthogonal to the axis of the cylinder. This is shown in more detail in FIG. 7, and FIG. 8 shows the case where the cylinder is tilted.

In FIG. 7, a three-dimensional model surrounded by virtual lines
100 represents a three-dimensional space, and two facing surfaces 100a, 100
The cylindrical body 101 whose both end surfaces are in contact with the central portion of b represents, for example, a part of the bonding wire. First, as shown in FIG. 7, when a light beam (LB) is scanned from above in the drawing along a plane PL ₁ orthogonal to the axis of the cylindrical body 101, the scanning line SL ₁ is formed on the surface of the cylindrical body 101. It is formed. Reflected light from the scanning line SL ₁ (indicated by an arrow in the figure) is reflected in multiple directions according to the surface curvature of the cylindrical body 101, but all reflected light is on the same plane orthogonal to the axis of the cylindrical body 101. That is, it passes through the plane PL ₁ . Therefore, the inner wall of the dome (2
In a), the luminescent line indicated by a broken line along the curved surface of the inner wall of the dome
BL ₁ is drawn. Here, the bright line BL ₁ coincides with the direction of the scanning line SL ₁ (light beam scanning direction), that is, the plane PL ₁ , and passes through the pole of the dome.

On the other hand, as shown in FIG. 8, an inclined cylinder body
When the light beam (LB) is scanned from the plane PL ₂ corresponding to the plane PL ₁ described above with respect to 201, the scanning line having the same shape as the end face 201a (ellipse) of the cylinder 201 is formed on the surface of the cylinder 201. SL ₂ will be drawn. The reflected light (indicated by an arrow in the figure) from the scanning line SL ₂ does not pass through the plane PL ₂ but passes through a curved surface having an inclination angle according to the inclination of the cylindrical body 201. Therefore,
Bright line BL ₂ drawn on the inner wall of the dome by many reflected lights
Is a predetermined curve defined by the bending degree of the curved surface and the curvature of the inner wall of the dome, and the drawing position is the cylindrical body 201.
It will deviate from the pole of the dome according to the angle formed by the plane PL ₂ .

FIG. 9 is a diagram showing an example of bright lines drawn on the inner wall of the dome by the reflected light from the wire-shaped object in the present invention, and is a diagram in which the inner wall (2a) of the dome is replaced with a plane. In the figure, the circle SS surrounding the circumference indicates the equator, the center PP indicates the pole, and the broken line indicates the scanning direction of the light beam (LB). The light beam is scanned from the upper side to the lower side in the figure.
Four lines AA, BB, CC, DD shown by a plurality of continuous arrows respectively represent bright lines (BL). That is, the bright line AA is when the cylinder (wire-shaped object) is arranged at right angles to the light beam, and the bright lines BB and CC are when the cylinder is obliquely arranged with respect to the light beam. Is. Furthermore, the bright line DD is the case where the cylinder is arranged at a right angle to the light beam and the cylinder is rotated about the axis of the light beam by a predetermined amount. In FIG. 9, for example, one arrow indicates 1
It corresponds to the information detected by the two optical sensor cells (21).

Here, when a new detection is made by another photosensor cell in accordance with the scanning of the light beam, the direction of the arrow, that is, the direction of the reflected light (RL) is changed from the address change of these two photosensor cells. Is determined. Then, by connecting a number of arrows whose directions have been determined, the bright line (BL)
It is possible to obtain the degree of curve of B, the position information of the center of the bright line, and the like.

From the above, by knowing the position of the bright line drawn on the inner wall of the dome and the degree of bending,
It is possible to measure the shape of the cylinder in three-dimensional space,
By comparing the measured data with the reference data, the quality of the cylindrical body,
Specifically, it is possible to judge the pitch of the bonding wire and the abnormal proximity between the wire and the chip. Therefore, the measurement accuracy of the wire-shaped object can be improved, and the measurement can be performed at high speed. As a result, it becomes possible to accurately and automatically inspect the pitch determination of the bonding wires and the abnormal proximity between the wires and the chips in a semiconductor device having a large number of bonding wires in recent years.

FIG. 10 is a view showing another embodiment of the wire-shaped object measuring apparatus according to the present invention. Comparing the device for measuring a wire-shaped object shown in FIG. 5 with the device shown in FIG. 10, the light beam scanning means 30 and the dome in this embodiment are compared.
The configuration of the pole portion (20b) of 20 and the processing means 51-54, 70-90 is different from that of FIG. First, as shown in FIG. 10, the light beam scanning means 30 in this embodiment is provided with two vibrating mirrors for scanning the light beam. That is, the light beam scanning means 30 scans the light beam from the beam generation source 31 supplied via the lens group 32 in the X-axis direction, and the first vibrating mirror 331 and the Y-beam.
A second vibrating mirror 332 that scans in the axial direction. As a result, the light beam LB output from the light beam scanning means 30 can be scanned in any direction on the XY plane. Here, according to the scanning direction (X and Y directions) of the light beam LB output from the light beam scanning means 30, a circular hole 20b is provided at the pole of the dome 20.

The outputs of the plurality of photosensor cells 21 arranged on the inner wall of the dome 20 are supplied to the neural net 51 via the corresponding amplifiers 41 to 4n, respectively.
The output of the net 51 is supplied to the angle calculation means 52. The scanning position control means 54 controls the light beam scanning means 30 according to the output signal from the control means 8. Also, scanning position control means
The outputs of 54 and the control means 80 are supplied to the comparison means 70, which is used in the comparison processing of the output of the angle calculation means 52 and the position / direction data (reference data) stored in the dictionary 53 in advance. To be done. Then, the output of the comparison means 70 is supplied to the defect output means 90 such as a display device or a printer.

FIG. 11 is a diagram for explaining a neural net in the wire-shaped object measuring apparatus of FIG. As shown in FIG. 11 (a), the neural network
Reference numeral 51 includes an input layer S1, an intermediate layer S2, and an output layer S3, and each layer has a plurality of units (not shown). Each unit of the intermediate layer S2 is connected to all the units of the input layer S1 and the output layer S3 so that the output of the optical sensor cell that detects the light reflected from the wire (bonding wire) is learned by the weight between the units. It has become.

As a learning method of the neural net 51, specifically, the output of each optical sensor cell 21 is measured each time while changing the rotation angle α and the inclination β of the wire 1 shown in FIG. 11 (b). , Is input to the neural net 51, and the connection state (weight between units) of the net is taught so that the corresponding rotation angle α and inclination β can be obtained as output. This makes it possible to obtain the corresponding rotation angle α and inclination β when the reflected light from the wire 1 is input at the time of actual measurement. Here, the inclination β (90 ° -θ) of the wire 1 needs to be smaller than 45 degrees, and when the angle β is larger than 45 degrees, the light reflected on the surface of the wire is Will not reach the dome (northern hemisphere) and will head toward the southern hemisphere, which is not preferable.

Then, as shown in FIG. 11C, the light beam is sequentially scanned, and the result (angle data of the rotation angle α and the inclination β of the bonding wire) obtained by the neural net 51 is stored in the storage means. Stored in MR. This storage means
The data stored in MR is combined and the three-dimensional shape of the bonding wire is measured. That is, the wire profile can be calculated by measuring the angle at each position of the bonding wire to be measured while scanning the light beam and adding the angle components while reading the angle component. If a neural net is used here, not only can the calculation for obtaining the rotation angle α and the inclination β be performed at high speed, but, for example, the noise beam reflected from the surface of the semiconductor chip (40) by the light beam (LB), etc. It is also advantageous in terms of suppressing the influence of and making accurate measurement.

12 to 14 are views for explaining an example of the scanning operation of the light beam in the wire-shaped object measuring apparatus of FIG. 10, and reference numerals 1a to 1d are bonding wires, SL (SLa to SLd, etc.). ) Indicates a scan line. First,
In an example of the scanning operation of the light beam, as shown in FIG. 12, the light beam (LB) is scanned in a rectangular shape along the periphery of the chip 10 and sequentially along the scanning lines SLa, SLb, SLc, SLd. The light beam is scanned as follows. Then, the angle (height) of the central position of the bonding wires 1a, 1b, 1c, 1d is detected, and the bonding wires in the normal state (see, for example, FIG.
(a)) and a defective bonding wire (for example, FIG.
Defective wires are detected by the difference in the height of the central position of the wires from (b) to (d). In this way, the scanning of the light beam may be performed so that only the central position of each bonding wire is irradiated. However, in this case, it is not necessary to perform complicated calculation, so
Very fast wire inspection can be performed without the use of a net. However, it is difficult to sufficiently detect defects in the entire wire.

Next, in another example of the scanning operation of the light beam, as shown in FIG. 13, the light beam (LB) is scanned a plurality of times in a rectangular shape along the periphery of the chip 10, and sequentially,
Scanning lines _{SLa 1, SLb 1, SLc 1} , SLd 1, SLa 2, SLb 2, SLc 2, SLd 2, the light beam is scanned along ... to. Then, the (angle) heights of a plurality of positions of the bonding wires 1a, 1b, 1c, 1d are detected, and the defects (defects) of the wires are inspected.

In another example of the scanning operation of the light beam, as shown in FIG. 14, the light beam (LB)
Are scanned a plurality of times so as to reciprocate with respect to each side of the chip 10, and sequentially scan lines SLaa, SLab, SLac; SLba, SLbb, SLbc, ...
The light beam is scanned along the line. Then, the heights of the bonding wires 1a, 1b, 1c, 1d at a plurality of positions are detected, and the defects of the wires are inspected. Here, the scanning interval of the light beam (for example, between the scanning lines SLaa and SLbb, or SL
By shortening the length (between a ₁ and SLa ₂ ) and scrutinizing the points where defects are likely to occur, it is possible to sufficiently detect defects in the entire wire. This is
The same applies to the scanning operation of the light beam shown in FIG.

[0041]

As described above in detail, according to the wire shape measuring method and apparatus of the present invention, the surface of the wire shape is linearly scanned with the light beam, and the surface of the wire shape is scanned. Detecting the reflected light with a plurality of optical sensor cells arranged on the inner wall of the reflected light detecting means, by measuring the shape of the wire based on the signal from the optical sensor cell,
It is possible to accurately measure the wire-shaped object in a short time.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a wire shape measuring apparatus according to the present invention.

FIG. 2 is a diagram for explaining the characteristics of reflected light from a wire-shaped object, which is the principle of the present invention.

FIG. 3 is a diagram for explaining a bright line drawn on the inner wall of the dome by the reflected light from the wire-shaped object which is the principle of the present invention.

FIG. 4 is a conceptual diagram showing how a three-dimensional shape of a wire-shaped object is reconstructed from the direction of reflected light, which is the principle of the present invention.

5 is a diagram showing a modified example of the wire-shaped object measuring apparatus shown in FIG. 1. FIG.

6 is a diagram showing an inspection table inside a dome in the measuring device for a wire-shaped object shown in FIG. 5;

FIG. 7 is a diagram showing reflected light when a wire-shaped object is arranged at a right angle to a light beam in the present invention.

FIG. 8 is a diagram showing reflected light when a wire-shaped object is obliquely arranged with respect to a light beam in the present invention.

FIG. 9 is a diagram showing an example of bright lines drawn on the inner wall of the dome by reflected light from a wire-shaped object in the present invention.

FIG. 10 is a view showing another embodiment of the wire shape measuring apparatus according to the present invention.

11 is a diagram for explaining a neural net in the wire-shaped object measuring apparatus of FIG.

12 is a view for explaining an example of a light beam scanning operation in the wire-shaped object measuring apparatus of FIG.

13 is a diagram for explaining another example of the scanning operation of the light beam in the wire-shaped object measuring apparatus of FIG.

14 is a diagram for explaining still another example of the scanning operation of the light beam in the wire-shaped object measuring apparatus of FIG.

FIG. 15 is a diagram showing a state of a bonding wire for connecting a semiconductor chip and a lead frame.

FIG. 16 is a diagram for explaining a problem in a conventional technique for measuring a wire-shaped object.

FIG. 17 is a diagram showing an example of a conventional method for measuring a wire-shaped object.

[Explanation of symbols]

 1, 11 ... Wire-shaped object (bonding wire) 2, 20 ... Reflected light detecting means (dome) 3, 30 ... Light beam scanning means 4, 41-4n ... Amplifier 5 ... Computing means 6 ... Reconstructing means 7 ... Defect discrimination Means 8, 80 ... Control means 9 ... Output means 10 ... Semiconductor chip (IC chip) 40 ... Lead frame (package) 51 ... Neural net (arithmetic means) 52 ... Angle calculation means 53 ... Dictionary 54 ... Scan position control means 70 … Comparison means 90… Defect output means

Claims (6)

[Claims] 1. A method for measuring a wire-shaped object (1, 11) having a substantially circular cross section and a total reflection surface for totally reflecting irradiated light, wherein a light beam ( (LB) linearly scanning the light beam, and the reflected light (RL) from the surface of the wire-shaped object is arranged on the inner wall (2a) of the reflected light detection means (2, 20) that covers the wire-shaped object. It comprises a reflected light detection step of detecting with a plurality of optical sensor cells (21), and a three-dimensional shape measuring step of measuring the three-dimensional shape of the wire-shaped object based on the output signals of the plurality of optical sensor cells. And the method of measuring wire-shaped objects. 2. The three-dimensional shape measuring step includes the steps of recognizing the positions of a plurality of optical sensor cells that have detected the reflected light on the inner wall of the reflected light detecting means, and the positions of the recognized plurality of optical sensor cells. Measuring the three-dimensional shape of the wire-shaped object based on the method. 3. A device for measuring a wire-shaped object (1, 11), comprising: a light-beam scanning means (3, 30) for linearly scanning a surface of the wire-shaped object with a light beam (LB); A reflected light detecting means (2) provided so as to cover the object, and a plurality of photosensor cells (a) attached to the inner wall (2a) of the reflected light detecting means so that the light receiving surface faces the inside of the reflected light detecting means ( 21), wherein each of the photosensor cells is provided with an address indicating the position on the inner wall of the reflected light detecting means, and a plurality of reflected light (RL) from the surface of the wire-shaped object is received. Computation means (5, 51) for computing the direction of the bright line (BL) projected on the inner wall of the reflected light detection means by the reflected light, based on the output signal of the photosensor cell and the address of the photosensor cell, The three-dimensional shape of the wire-shaped object is reconstructed based on the calculation result of the calculation means. Apparatus for measuring a wire-shaped, characterized in that a reconstruction means (6,52) for forming. 4. The wire-shaped object has a substantially circular cross section and a total reflection surface for totally reflecting the irradiated light beam, and connects the semiconductor chip (10) and the lead frame (40). The wire-shaped measuring device according to claim 3, which is a bonding wire to be used. 5. The wire-shaped object measuring device according to claim 3, wherein the reflected light detecting means (2) is formed as a hemispherical dome. 6. The neural network (51) according to claim 6,
4. The apparatus for measuring a wire-shaped object according to claim 3, wherein the reconstructing unit is composed of an angle calculating unit.