JP2006317391A - Slit light irradiation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a slit light irradiation device capable of generating uniform slit light having no irregularities. <P>SOLUTION: This slit light irradiation device, which is a slit light irradiation device used for a pattern inspection method and a pattern inspection device, is characterized by being equipped with a light emission part for irradiating light; a light diffusion part for diffusing uniformly the light irradiated from the light emission part; the first parallel light generation part for receiving the uniform diffused light acquired from the light diffusion part, and generating parallel light; a slit light generation part for receiving the parallel light from the first parallel light generation part, and generating slit light having the width determined beforehand; and the second parallel light generation part for receiving the slit light having the width determined beforehand from the slit light generation part, and generating parallel light having the same width. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a pattern inspection method for inspecting a pattern formed by printing or etching on a green sheet or a film carrier using a light cutting method, and a slit light irradiation apparatus used in a pattern inspection apparatus.

Conventionally, PGA (Pin (Pin)
Grid Array) is known. The PGA uses a ceramic substrate as a base of a package to which a chip is attached, and performs wiring up to a lead wire extraction position.
In order to make this ceramic substrate, what is called a green sheet obtained by kneading alumina powder with a liquid binder to form a sheet is used, and a paste containing a high melting point metal is screen-printed on the green sheet. By firing such a sheet, so-called simultaneous firing is performed in which the green sheet is sintered and the paste is metallized.

As another mounting technique, TAB (Tape Automated Bonding) is known.
In the TAB method, a copper foil pattern formed on a polyimide tape carrier (TAB tape) is joined to an electrode of an IC chip to form an external lead. The copper foil pattern is formed by attaching a copper foil to the tape carrier with an adhesive and etching it.

In such a green sheet or tape carrier, a pattern is visually inspected by a human using a microscope after pattern formation. However, in order to visually inspect a fine pattern, there is a problem that skill is required and the eyes are abused. Therefore, as an alternative to visual inspection, a pattern inspection method has been proposed in which a pattern formed on a tape carrier or the like is imaged with a TV camera and automatically inspected. One type of pattern inspection method is a light cutting method. In this light cutting method, a pattern to be inspected is irradiated with line-shaped light, the irradiated portion is imaged by an imaging means such as a line sensor, and predetermined image processing is performed to determine whether the pattern to be inspected is good or bad. It is to be determined.

As a light irradiation device for generating the line-shaped light, the light emitted from the light source is guided to a desired portion through the transparent optical fiber bundle, and the transparent optical fibers are arranged in a line at the desired portion to form a line shape. Have been proposed (see, for example, Patent Document 1)
.

FIG. 8 is a view showing a pattern inspection apparatus using a conventional light irradiation apparatus. The configuration and operation of this conventional pattern inspection apparatus will be described with reference to FIG.
The pattern inspection apparatus 9 includes a light irradiation device 90 and a camera unit 95. The light irradiation device 90 includes a light source 94, a transparent cylinder 921 that irradiates the pattern 961 on the printed wiring board 96 in a line shape, and a transparent optical fiber bundle 93 that optically connects the two.

The transparent optical fiber bundle 93 is bundled in a substantially circular shape on the light source 94 side,
On the other hand, the light irradiation side is aligned along the axial direction of the transparent cylinder 921.
A plane mirror 9 is provided between the light irradiation end of the transparent optical fiber bundle 93 and the transparent cylinder 921.
2 and a milky white plate 922 are provided. A printed wiring board 96 as an object to be inspected is fixed on a moving table 97 during inspection.

In the pattern inspection apparatus 9, the light emitted from the light source 94 is guided to the transparent cylinder 921 through the transparent optical fiber bundle 93 and the like, and is irradiated on the printed wiring board 96.
At this time, the detection light reflected from 961 on the printed wiring board 96 is transmitted to the camera unit 95.
Catch at. The detection light caught by the camera unit 95 is converted into a binary image and subjected to comparison inspection with the master pattern by a pattern analysis device (not shown). Thereby, the presence or absence of a defect in the pattern is detected.
The light irradiation device 90 and the camera unit 95 are integrated by a frame,
It scans relatively with respect to the printed wiring board 96 which is a to-be-inspected object.

However, the conventional light irradiation device 90 has a problem that the amount of light to be irradiated is not uniform, and as a result, there is a problem that the accuracy and reliability of pattern inspection are affected. The reason why the amount of light is non-uniform is considered as follows. That is, the light from the light source 94 is guided by the transparent optical fiber bundle 93, and the surface of the transparent optical fiber bundle 93 with respect to the light source 94 is bundled in a circular shape. For this reason, the light quantity which enters into the transparent optical fiber bundle 93 is a circular transparent optical fiber bundle 9.
This is because the central portion and the outer peripheral portion in FIG. Therefore, since the transparent optical fiber bundle 93 is aligned along the axial direction of the transparent cylinder 921 on the light irradiation side, the light amount of the slit-shaped light irradiation is not uniform.

There has been proposed a light irradiation apparatus that solves such a problem that the amount of light is not uniform (see, for example, Patent Document 2). This light irradiating device is characterized by a rod-shaped lamp, a plate-shaped light guide, a cold filter, and a cold mirror.

FIG. 9 shows this light irradiation apparatus.
As shown in FIG. 9, this light irradiation device is a light guide part for guiding light from a rod-shaped lamp 81 serving as a light source and the light from the rod-shaped lamp 81 in a line and toward the pattern in a line. A cold filter 83 that reflects infrared light in the light from the plate-shaped light guide 82 and the rod-shaped lamp 81 and transmits visible light, and the rod-shaped lamp 81
The main part is a cold mirror 84 that transmits infrared rays in the light from the light beam and reflects visible light in the direction of the cold filter 83. These main parts are stored in the lamp house 85.

The following components are required to be housed in the lamp house 85. A socket 815 for supplying power to the rod-shaped lamp 81, an air intake port 852 for taking air into the lamp house 85, a fixing plate 855 for fixing the plate light guide 82 to the lamp house 85, and air taken from the air intake port 852 are discharged. And an air suction blower 865 for sucking air, and a pipe 864 connected to the air suction blower 865.

According to the light irradiation apparatus having such a configuration, the rod-shaped lamp 81 is used as a light source, and the light is irradiated onto the pattern to be inspected using the plate-shaped light guide 82. Therefore, the irradiation light is irradiated in a uniform line shape, and a camera unit (not shown).
) In a line-shaped imaging field of view, uniform light irradiation can be performed on a pattern of a printed wiring board (not shown).

The applicant has not yet found prior art documents related to the present invention by the time of filing other than the prior art documents specified by the prior art document information described in this specification.
Japanese Utility Model Publication No. 5-31562 JP 7-333169 A

However, even if such a light irradiation apparatus can irradiate the inspection target with uniform line-shaped light, there are the following drawbacks.

(1) Since the pattern to be inspected is increasingly miniaturized, the inspectable minimum line width is about 10 μm and the inspectable minimum line width is about 10 μm.
In order to cope with the minimum detection defect size of about 4.5 μm (detection of disconnection or short circuit when the resolution is 1.5 μm), a line-shaped slit light having a width of about 5 μm is required. It is difficult to generate slit light having such a width.
(2) Since a plate-shaped light guide is used, it occupies a certain volume when incorporated in a pattern inspection apparatus, and there is a restriction on the apparatus configuration.
(3) Since the lamp house has a high temperature and requires forced cooling, it is necessary to mechanically and electrically suck and release air, which greatly limits the miniaturization of the apparatus.
(4) Since the plate-shaped light guide requires a high degree of processing, it takes a lot of time and money to manufacture a predetermined number of homogeneous plate-shaped light guides.
(5) Since the light source is a rod-shaped lamp, it is possible to irradiate a long inspection area, but only the light from the rod-shaped lamp is reflected by a cold mirror.
It is difficult to completely eliminate the uneven brightness of the light that irradiates the inspection area.

The present invention has been made to solve the above-described problem, and is a pattern capable of generating slit light that uniformly irradiates a predetermined width and length for detecting a defect of an inspection work with high accuracy and without error. It aims at providing the slit light irradiation apparatus used for an inspection method and a pattern inspection apparatus.

The slit light irradiation device according to the present invention is a slit light irradiation device used in a pattern inspection method and a pattern inspection device, and includes a light emitting unit that emits light and light that uniformly diffuses light emitted from the light emitting unit. A diffusion unit, a first parallel light generation unit that generates parallel light by receiving the uniform diffused light obtained by the light diffusion unit, and a predetermined unit that receives the parallel light from the first parallel light generation unit A slit light generation unit that generates slit light having a predetermined width, and a second parallel light generation unit that receives the slit light having a predetermined width from the slit light generation unit and generates parallel light. It is characterized by this.

And in this slit light irradiation apparatus, a light-diffusion part is (phi) 60 mm x 70 m.
m × 10 mm to 15 mm, and the first and second parallel light generation units and the slit light generation unit are 75 mm to 85 mm × 10 mm to 15 mm.

In addition, the slit light generation unit has 4.0 μm to 6.0 μm × 20 mm to 35 m.
It is characterized in that m slits are formed.

Further, in this slit light irradiation device, the light diffusing unit is an integrating disc sphere, the first and second parallel light generating units are cylindrical lenses, and the slit light generating unit is a glass mask. It is what.

Moreover, the slit light irradiated from this slit light irradiation apparatus is 4.0 micrometers-6.
It is 0 μm × 20 mm to 35 mm.

By using the slit light irradiation device according to the present invention in a pattern inspection method and a pattern inspection device using a light cutting method, a first imaging region is set on the base material surface of the inspection work, and the first from the slit light irradiation device. By irradiating the first imaging region with the first slit light and imaging the first imaging region with the first line sensor camera, it is possible to detect a defect in a portion close to the base material such as a bottom short circuit, for example. it can. Further, a second imaging region is set on the upper surface of the conductor of the inspection work, and the second imaging region is irradiated with the second slit light from the other slit light irradiation device. By imaging with the second line sensor camera, it is possible to detect a defect in the upper part of the conductor such as an upper defect. As a result, according to the present invention, a pattern to be measured having a measurement pattern width of 10 μm and a pattern interval of 10 μm is measured with a minimum detection defect size of 5 μm.
It becomes possible to detect the defect of the pattern to be measured accurately and accurately in units.

BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described in detail with reference to the drawings together with an outline of a pattern inspection apparatus using a slit light irradiation apparatus according to the present invention.
FIG. 1 is a block diagram of a pattern inspection apparatus using the slit light irradiation apparatus according to the present invention, FIG. 2 is a schematic sectional view of the slit light irradiation apparatus according to the present invention, and FIG. 3 is used for the slit light irradiation apparatus according to the present invention. Fig. 4 is a schematic plan view of a slit light generating unit that generates slit light having a predetermined width, and Fig. 4 is a schematic diagram of slit light emitted from the slit light irradiation apparatus according to the present invention.

Since the slit light irradiation apparatus according to the present invention is used in a pattern inspection method and apparatus, first, the configuration of such a pattern inspection apparatus will be shown and the functions of the main parts will be described. Thereafter, the configuration of the slit light irradiation apparatus according to the present invention will be described, and the imaging of the pattern to be measured when actually used will be described.

In FIG. 1, 1 is an inspection work such as a green sheet, 2 is an XY table on which the inspection work 1 is placed, 3a and 3b are line sensor cameras for imaging the inspection work 1,
4a, 4b, 4c, and 4d are slit light irradiation devices according to the present invention that illuminate the inspection work 1, and 5 is an inspection of the pattern to be measured by comparing the master pattern as a reference with the pattern to be measured captured by the line sensor camera 3. An image processing apparatus 6, a host computer 6 for controlling the entire apparatus, and a display apparatus 7 for displaying inspection results.

The image processing apparatus 5 includes an alignment unit that aligns the master pattern and the measured pattern, a binarization processing unit that binarizes the gray image of the measured pattern, and performs predetermined processing on the measured pattern. The first and second measured patterns and the master pattern are subjected to predetermined processing to create a reference master pattern, and the first measured pattern is compared with the reference master pattern. The inspection means and the second inspection means for comparing the second measured pattern and the master pattern are configured. At least a part of the alignment means and the first and second inspection means is constituted by a computer.

The host computer 6 and the computer in the image processing apparatus 5 are, for example, CP
U, a hardware resource having a storage device and an interface, and a program for controlling these hardware resources. The CPU executes a predetermined process according to a program stored in the storage device.

Next, the slit light irradiation apparatus according to the present invention will be described.
FIG. 2 is a sectional view showing a schematic configuration of the slit light irradiation devices 4a, 4b, 4c, and 4d according to the present invention. The slit light irradiation devices 4a, 4b, 4c, and 4d adopt the same configuration (hereinafter also referred to as the slit light irradiation device 4).

Although not shown, the slit light irradiation device 4 includes a light emission source serving as a light emitting unit for irradiating light to the outside. This light source has the same configuration as a conventional light source, and basically includes a light source such as a halogen lamp, an illumination power source that supplies power to the light source, and a condenser lens. Moreover, this light emission source and the slit light irradiation device 4 are connected by a glass fiber. And the light emitted by the light source is collected by the condenser lens,
The slit light irradiation device 4 is irradiated through this glass fiber.

In FIG. 2, 40 is a light guide in which a plurality of glass fibers for irradiating light from a light source (not shown) to the slit light irradiation device 4 is bundled, and 41 is a light diffusion for uniformly diffusing the light irradiated from the light guide 40. Integral disk sphere 42 is an integral disk sphere 41
The first cylindrical lens 44 that is partially connected to the integrating disc sphere 41 serving as a first parallel light generating unit that receives the uniform diffused light from the light and generates parallel light is provided from the first cylindrical lens 42. A glass mask in which a slit 43 is provided at a central portion serving as a slit light generating unit that receives parallel light and generates slit light, and 45 is a second parallel light that receives the slit light from the glass mask 44 and generates parallel light. A second cylindrical lens 46 serving as a generation unit is a lamp house that stores the components described above.

Here, the external shape of the integrating disc sphere 41 is φ60 mm × 70 mm × 10 mm to 15 mm.
The outer shapes of the first cylindrical lens 42, the glass mask 44, and the second cylindrical lens 45 are 75 mm to 85 mm × 10 mm to 15 mm.
And, as shown in FIG. 3, the glass mask 44 has a central portion of 4.0 μm˜
A slit 43 of 6.0 μm × 20 mm to 35 mm is formed.

The operation of the thus configured slit light irradiation device 4 will be described.
Light emitted from a light source (not shown) is incident on the integrating disc sphere 41 by a plurality of optical fibers bundled by a light guide 40. The incident light is integrated disc sphere 4
The light is diffused within the light beam 1 to be a uniform amount of light, and is incident on the first cylindrical lens 41.

In response to the light from the integrating disc sphere 41, the first cylindrical lens 42 generates parallel light. In response to the parallel light, the slit light generation unit 44 generates slit light having a narrow width of about 5 μm (width) × about 35 mm (length) according to the shape of the slit 43. In response to the narrow beam-like parallel light, the second cylindrical lens 45 generates slit light as it is.
In this way, uniform and uniform slit light having a narrow width of about 5 μm and a length of about 35 mm can be generated (see FIG. 4).

Next, imaging of a pattern to be measured using the slit light irradiation apparatus according to the present invention will be described with reference to FIG.
First, the inspection work 1 is illuminated by the first slit light irradiation devices 4a and 4b and imaged by the first line sensor camera 3a, and the inspection work 1 is illuminated by the second slit light irradiation devices 4c and 4d, and the second The line sensor camera 3b takes an image.

At this time, each of the first slit light irradiation devices 4a and 4b applies linear first slit light parallel to the first imaging region to the linear first imaging region of the inspection work 1, respectively. Oblique irradiation from different irradiation directions. The first imaging region is set on the surface of the base material 11 of the inspection work 1. That is, the slit light from the slit light irradiation device 4 a and the slit light from the slit light irradiation device 4 b overlap on the base material surface of the inspection work 1. The focus of the first line sensor camera 3a is set so as to match the first imaging region.

On the other hand, the second slit light irradiation devices 4c and 4d differ from each other in the linear second imaging region of the inspection work 1 with the linear second slit light parallel to the second imaging region. Irradiate obliquely from the irradiation direction. The second irradiation region is set on the upper surface of the conductor 12 of the inspection work 1. That is, the slit light from the slit light irradiation device 4 c and the slit light from the slit light irradiation device 4 d are the conductor 1 of the inspection work 1.
2 overlap. The focus of the second line sensor camera 3b is the second
It is set so as to fit the imaging area.

The line sensor cameras 3a and 3b capture the first and second imaging regions from a direction different from the irradiation direction of the slit light. As shown in FIG. 5, the slit light irradiation device 4a.
If the slit light irradiated from IBA is IBa, the slit light irradiated from the slit light irradiation device 4b is IBb, and the reflected light toward the line sensor camera 3a is OBa,
The slit light irradiation devices 4a and 4b are arranged so that the slit light IBb is irradiated from a different side from the slit light IBa with the reflected light OBa interposed therebetween.

Similarly, the slit light irradiated from the slit light irradiation device 4c is IBc, the slit light irradiated from the slit light irradiation device 4d is IBd, and the line sensor camera 3b.
When the reflected light toward OB is OBb, the slit light irradiation devices 4c and 4d are so arranged that the slit light IBd is irradiated from a different side from the slit light IBc with the reflected light OBb interposed therebetween.
Is placed. The reason why the two slit light irradiating devices 4a and 4b are used to irradiate obliquely from two opposite directions is to prevent shadows from being formed by the conductor on the inspection work 1. The reason for using the slit light irradiation devices 4c and 4d is also the same.

FIG. 6A is a plan view showing the slit light irradiated onto the inspection work 1 from the first slit light irradiation devices 4a and 4b and the first imaging region of the first line sensor camera 3a, FIG. ) Is a cross-sectional view of the inspection work 1 of FIG. Slit light IBa,
Since IBb is applied to the inspection work 1 obliquely from above and the conductor 12 of the inspection work 1 has a trapezoidal cross section as shown in FIG. In this case, the slit light beams IBa and IBb are shaped as shown in FIG. At this time, the image signal output from the first line sensor camera 3a is as shown in FIG.

In FIG. 7, S <b> 11 is a portion corresponding to the base material 11 in the image signal, and S <b> 12 is a portion corresponding to the conductor 12. In the imaging region of the line sensor camera 3a shown in FIG. 6A, the portion of the conductor 12 in the imaging region is not irradiated with the slit lights IBa and IBb, so the portion S12 corresponding to the conductor 12 of the image signal becomes dark and the base material 11 The portion S11 corresponding to is brightened.

In this way, a desired inspection work 1 can be imaged. And since the slit light irradiation device according to the present invention is used, slit light with uniform brightness and evenness is irradiated over a length of about 35 mm with a width of about 5 μm. Since it is possible to capture an image in a dark place with a certain darkness, stable and reliable processing is possible when the captured pattern to be measured is binarized.

The present invention can be applied to an illumination device for inspecting a pattern formed on a green sheet or a film carrier by printing or etching.

It is a block diagram which shows the structure of the pattern inspection apparatus in the 1st Embodiment of this invention. It is a schematic sectional drawing of the slit light irradiation apparatus which becomes this invention. It is a plane schematic diagram of the glass mask which is a slit light production | generation part which produces | generates the slit light of the predetermined width | variety used for the slit light irradiation apparatus which becomes this invention. It is a schematic diagram of the slit light irradiated from the slit light irradiation apparatus which becomes this invention. It is a figure for demonstrating the relationship between the slit light which injects into a test | inspection workpiece | work, and reflected light. It is the top view which shows the slit light irradiated on the test | inspection workpiece | work from the 1st illumination device, and the 1st imaging area of a 1st line sensor camera, and sectional drawing of a test | inspection work. FIG. 7 is a waveform diagram of an image signal output from the first line sensor camera when the inspection work of FIG. 6 is imaged. It is a figure which shows the pattern inspection apparatus using the conventional light irradiation apparatus. It is a figure which shows another conventional light irradiation apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inspection workpiece 2 XY table 3a, 3b Line sensor camera 4, 4a, 4b, 4c, 4d Slit light irradiation apparatus 5 Image processing apparatus 6 Host computer 7 Display apparatus 40 Light guide 41 Integral disk ball 42, 45 Cylindrical lens 43 Slit 44 Glass mask 46 Lamp house

Claims (5)

A slit light irradiation device used in a pattern inspection method and a pattern inspection device,
A light emitting unit that emits light;
A light diffusing unit that uniformly diffuses the light emitted from the light emitting unit;
A first parallel light generation unit that receives the uniform diffused light obtained by the light diffusion unit and generates parallel light;
A slit light generator that receives the parallel light from the first parallel light generator and generates slit light of a predetermined width;
A second parallel light generation unit that receives the slit light of a predetermined width from the slit light generation unit and generates parallel light of the same width;
A slit light irradiation apparatus comprising: The light diffusing unit is 60 mm × 70 mm × 10 mm to 15 mm, and the first and second parallel light generating units and the slit light generating unit are 75 mm to 85 mm × 10 6.
The slit light irradiation device according to claim 1, wherein the slit light irradiation device has a thickness of mm to 15 mm. The slit light irradiation device according to claim 1, wherein a slit of 4.0 μm to 6.0 μm × 20 mm to 35 mm is formed in the slit light generation unit. 2. The slit light according to claim 1, wherein the light diffusion unit is an integrating disc sphere, the first and second parallel light generation units are cylindrical lenses, and the slit light generation unit is a glass mask. Irradiation device. The slit light irradiation apparatus according to claim 1, wherein the irradiated slit light is 4.0 μm to 6.0 μm × 20 mm to 35 mm.

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