KR20100075371A - Wiring pattern inspection apparatus - Google Patents

Abstract

In the inspection apparatus of a pattern, illumination light is irradiated obliquely from the side in which the wiring pattern is formed with respect to the TAB tape 5 so that detection of the upper shape of a pattern and detection of a lower shape can be performed simultaneously. Inspection area from a side opposite to the side on which the first illuminating means 1a described above, the illuminating light is irradiated obliquely from the side on which the wiring pattern is formed, and the side on which the wiring pattern is formed Third illumination means 1c for irradiating the illumination light so as to be perpendicular to orthogonal to, is provided, and is illuminated at the same time in three directions to capture an image of the wiring pattern with the imaging means 11. By illuminating in this way, the shape of the upper part and the lower part of a wiring pattern can be detected simultaneously by one measurement, and defects, such as a lack of a part of upper part, can be detected.

Description

Wiring pattern inspection device {WIRING PATTERN INSPECTION APPARATUS}

The present invention relates to a pattern inspection apparatus capable of simultaneously measuring an upper line width and a lower line width of a wiring pattern formed on a light transmissive substrate such as a tape automated bonding tape (TAB) tape.

Generally, when a wiring pattern (hereinafter also referred to as a pattern) is formed on a substrate by etching, the cross section tends to have a trapezoidal shape having a lower width than the upper width. For this reason, if etching is insufficient, even if the upper line width is within the range of good products, thickening of the wiring called "source remaining" occurs in the lower portion, and adjacent wiring and short circuit (short) are generated. There is a possibility of causing it. For this reason, in the inspection of the wiring pattern, it is important to measure the width of the lower portion of the pattern.

As an inspection method which measures the width of the lower part of a pattern, it is known to perform illumination light through the board | substrate in which the pattern is formed (inspection by a transmission illumination) (refer patent document 1 and patent document 2, for example).

Patent document 1 shows that the line width of the lower part of a wiring pattern is measured by transmission illumination, and it detects whether the short circuit etc. generate | occur | produced. Also in FIG. 5 of patent document 2, it is shown by transmission illumination that the line width of the lower part of a wiring pattern can be measured.

<Patent Document 1> Japanese Patent Laid-Open No. 2003-303862

<Patent Document 2> Japanese Patent Application Laid-Open No. 2000-113191

Using transmitted light, the line width at the bottom of the pattern can be measured. However, the measurement of the upper line width is impossible. However, recently, it is desired to measure not only the line width at the bottom of the pattern but also the line width at the top. The reason is as follows.

The cross-sectional shape of the wiring pattern formed on the board | substrate is shown in FIG. As mentioned above, the cross section of the pattern formed by etching becomes a trapezoidal shape with a wider width lower than an upper portion. That is, as shown to Fig.9 (a), in the wiring pattern, the width | variety b of the lower part becomes a <b with respect to the width | variety a of upper part, and when height is set to h, the cross-sectional area S will be S = (a + b) × h / 2.

In recent years, however, due to miniaturization of wiring patterns, the lower line width is within the range of good products, but the upper line width is very narrow, and as shown in Fig. 9B, the cross-sectional shape of the wiring becomes triangular. There is.

When the cross-sectional shape becomes a triangle, as shown in Fig. 9B, when the width of the lower portion of the wiring pattern is b and the height is h, the cross-sectional area S 'becomes S' = b x h / 2, Even if the widths are the same, the cross-sectional area is smaller than in the case where the cross section is trapezoidal.

That is, compared with FIG. 9 (a), the cross-sectional area of FIG. 9 (b) is smaller in area by axh / 2.

The cross-sectional area of the wiring pattern is designed from the current value flowing in the pattern. Therefore, in the inspection apparatus of a pattern, the pattern whose cross-sectional area is smaller than an allowable range must be made into defect.

However, by measuring only the width of the lower portion of the wiring pattern, the magnitude of the cross-sectional area of the pattern cannot be known. In order to obtain the cross-sectional area, the widths of the wirings at the top and the bottom of the pattern must be measured.

By the way, in order to detect the line width of the upper part of a wiring pattern, it is known to use reflected illumination light.

Therefore, the pattern to be inspected is irradiated with the reflected illumination light to measure the line width of the upper part of the pattern, and then the transmissive illumination light is irradiated to measure the line width of the lower part of the pattern. .

In this method, however, two measurements, one measurement by the reflected illumination light and one measurement by the transmitted illumination light, are performed on one inspection pattern, and the inspection time becomes long. Here, an inspection apparatus capable of simultaneously measuring the line width at the top of the pattern and the line width at the bottom is desired.

This invention is made | formed in view of the said situation, and the objective of this invention is to make it possible to detect the shape of the upper part of a pattern, and the detection of the shape of a lower part simultaneously in the inspection apparatus of a pattern.

In the present invention, the above problems are solved as follows.

In the wiring pattern inspection apparatus which judges the good or bad of the said pattern based on the image image which irradiated illumination light to the wiring pattern formed on the light transmissive board | substrate, three different with respect to the pattern formed on the light transmissive board | substrate. Illumination means for illuminating from a direction is provided, and illumination is performed simultaneously from three directions.

The first illuminating means irradiates the illumination light so as to be obliquely incident on the inspection region from the side where the pattern of the substrate is formed. The second illuminating means irradiates the illumination light at an angle to the inspection region at an angle from the side opposite to the side on which the pattern of the substrate is formed. The third illuminating means irradiates the illumination light so as to be incident almost perpendicularly to the inspection region from the side opposite to the side on which the pattern of the substrate is formed.

By illuminating in this way, the shape of the upper part of a pattern and the shape of a lower part can be detected simultaneously, For example, although the shape of the lower part of a wiring pattern is normal, defects, such as a lack of a part of an upper part, can be detected. .

If necessary, the cross-sectional area of the pattern can be calculated based on the upper shape (line width) and the lower shape (line width) of the detected pattern. The cross-sectional area of the calculated pattern is compared with the allowable range, and if it is outside the allowable range, the pattern is made defective.

In this invention, the shape of the upper part and the lower part of a pattern can be detected simultaneously by a single measurement about an inspection pattern. Therefore, it is possible to detect a defect or the like of the wiring pattern without lengthening the inspection time.

1 is a block diagram of a wiring pattern inspection apparatus of an embodiment of the present invention. In addition, although the following Example demonstrates the case where a board | substrate is a film state workpiece | work which is a TAB tape or a COF (Chip On Film), this invention is applicable also to the pattern inspection of another board | substrate as long as it is light transmittance.

As shown in the figure, the pattern inspection apparatus according to the present embodiment includes a tape conveyance mechanism 20 and an unwinding reel 21 formed of an unwinding reel 21, a winding reel 22, and the like for conveying the TAB tape 5. Inspection unit 1 for irradiating the TAB tape 5 released from the illumination light to image the inspection pattern 6, scanning means 2 for scanning the inspection unit 1 on the inspection pattern 6 of the TAB tape, The marker part 3 which attaches a mark to a pattern is provided.

In the marker part 3, marks, such as coloring, are punched with respect to the pattern judged to be defective so that a part which is a defective article may be immediately confirmed by visual observation.

In addition, the pattern inspection apparatus is provided with a control unit 4. The control part 4 controls the operation | movement of the test | inspection part 1, the marker part 3, and the tape conveyance mechanism 20, and detects the defect of a pattern based on the shape of the upper part and the lower part of the detected pattern. In addition, the cross-sectional area may be calculated based on the line widths of the upper and lower portions, and the quality and the defect of the pattern may be determined.

The inspection unit 1 irradiates the TAB tape 5 with the first light means 1a for irradiating the illumination light at an angle from the side on which the pattern is formed and the illumination light at an angle from the side opposite to the side on which the pattern is formed. 2nd illumination means 1b, 3rd illumination means 1c which irradiates an illumination light so that it may incline (almost) orthogonally to a test | inspection area | region from the side from which the pattern is formed, and 1st illumination means 1a In the same side as), it is provided in the direction immediately above the inspection area and includes an imaging means 11.

The light source of the 1st, 2nd, 3rd lighting means 1a, 1b, 1c uses LED in this Example, You may use a halogen lamp. When using a halogen lamp as a light source, the light from a lamp is guided by a light guide fiber, and it sets so that the incidence angle of the light radiate | emitted from a fiber may be set to a desired angle, respectively.

The imaging means 11 is a CCD line sensor or an area sensor which has light reception sensitivity to the wavelength of the said illumination light, for example.

In addition, on the light incidence side of the imaging means, a lens (not shown) is provided which enlarges and projects an area for inspecting the TAB tape 5. In addition, this lens is a combination of a plurality of lenses is stored in the barrel.

The control part 4 is the inspection part 1 by the lighting means of the 1st, 2nd, 3rd illumination means 1a, 1b, 1c, lighting of the illumination light, the imaging means of the imaging means 11, and the scanning means 2. ) And conveyance of the TAB tape 5 are controlled.

Moreover, the control part 4 determines the good or bad of a pattern based on the shape of the upper part and the lower part of the detected pattern. In addition, you may calculate the cross-sectional area of a pattern based on the line width of an upper part and a lower part, and may determine the good or bad of a pattern from this cross-sectional area.

To this end, the control unit previously inputs the line width of the upper part of the pattern, the allowable range of the lower line width, the allowable range of the cross-sectional area of the wiring pattern, and the like.

2 and 3 show enlarged views of the inspection unit 1. 2 is a perspective view of the inspection unit, and FIG. 3 is a cross-sectional view along the longitudinal direction of the TAB tape 5.

As shown in FIG. 2, in the first lighting means 1a and the second lighting means 1b, light of the same incident angle is incident from the front direction over the entire area of the inspection region, and from each direction. In order to illuminate so that the intensity of the incident light may be the same, a plurality of LEDs are arranged in an annular shape. For example, as shown in FIG. 3, the prism sheet 10b is disposed on the light output side of the LED 10a. It is a configuration installed. Further, a diffusion plate 10c is attached to the light output side.

The 3rd illumination means 1c arrange | positions LED10a along the linear | annual inspection area | region, and attaches the diffuser plate 10c to the light emission side.

4 shows a specific configuration example of the first illuminating means 1a and the second illuminating means 1b formed in the annular shape. The figure (a) shows the prism sheet cut | disconnected in fan shape, and the figure (b) shows A of the figure (a) when the lighting means was comprised using the prism sheet shown to the said figure (a). The emission direction of the light when viewed from the direction is shown, and the drawing (c) shows the light output when viewed from the B direction of the drawing (a) when the lighting means is configured using the prism sheet shown in the drawing (a). Indicates the direction.

The prism sheet 10b is arranged so that a large number of prisms having a triangular cross section is parallel to one side of the transparent sheet. As shown in Fig. 4 (a), the long axis direction of the prism is a circular arc of a fan shape. Cut fan-shaped to face tangentially. Then, the prism sheet is arranged in an annular shape and arranged on the light output side of the LED 10a attached on the support member 12. The diffusion plate 10c is again attached thereon to constitute the first lighting means 1a and the second lighting means 1b.

When the chief ray emitted from the LED 10a is parallel, the light is incident on the prism sheet 10b, and when viewed from the A direction of the drawing (a), the light is refracted by the prism and is parallel as shown in the drawing (b). While in a state, it enters into the imaging area R at a fixed angle. In addition, when viewed from the direction B in the figure (a), as shown in the figure (c), it is irradiated downward without refraction by the prism.

Returning to FIG. 1, the imaging means 11 image | photographs the test | inspection area | region illuminated simultaneously by the 1st, 2nd, 3rd illumination means 1a, 1b, 1c. In addition, the CCD used for the imaging means 11 is a line sensor, and an imaging area is an elongate area | region according to a CCD line sensor. The imaging means 11 moves in the width direction of the TAB tape 5 integrally with the first, second, and third illumination means 1a, 1b, and 1c to image the entire inspection area.

Next, the experimental result which investigated what kind of illumination should be performed in order to be able to measure the line width of the upper part of a pattern and the line width of a lower part at the same time is shown.

FIG. 5: shows the pattern of the sample to test | inspect, FIG. (A) is the figure which looked at the pattern from the upper surface, and (b) is sectional drawing A-A in the figure (a). In addition, the figure shows the result of observing the actual pattern with a laser microscope typically.

As shown in the drawings (a) and (b), the sample pattern has a width of about 20 μm in the lower portion, a width of 14 μm in the upper portion, a width of 3 μm in the inclined surface, and a height of the pattern about 7 to 8 μm. As shown in the figure, the upper part of the wiring is 83% missing as compared to the good product (the lower part is also missing, but the upper part is larger). Therefore, when this pattern is inspected by the pattern inspection apparatus, it is ideal to be able to detect that there is "83% lack" in the upper portion together with the line width of the lower portion.

In addition, the percentage of this deficiency is calculated and calculated | required from the brightness | luminance of each one of the pixel of the part which is missing in the image of the pattern imaged.

In the experiment, (a) the TAB tape was irradiated with the illumination light obliquely from the side opposite to the side where the first illumination means 1a, (b) the pattern was formed, from the side on which the pattern was formed. By using the third illuminating means 1c for irradiating the illumination light so as to enter the (nearly) orthogonal to the inspection area from the side opposite to the side on which the second illuminating means 1b and (c) patterns are formed, (a) (b) (c) The image of the sample pattern was imaged and compared with the image pick-up element 11, when the illumination of each of the three types of illumination was combined with the case of single illumination, respectively.

(1) When third lighting means 1c (transmission orthogonal) is not used

Illumination of only the first lighting means 1a (reflective tilting), illumination of only the second lighting means 1b (transmission tilting), of the first lighting means 1a and the second lighting means 1b About each of simultaneous illumination (reflection inclination + transmissive inclination), the image of the said sample pattern was imaged with the imaging means.

In any case, it is clear that the image is dark, the contrast is bad, not only the line width of the lower part of the pattern but also the upper line width of the upper part is difficult to check, and it is difficult to measure the line width of the pattern with high accuracy.

(2) When the sample pattern is illuminated only by the third illuminating means 1c (transmission orthogonal).

FIG. 6 (a) is a diagram schematically showing an image when the sample pattern is illuminated by only the third illumination means 1c (transmission orthogonal). In this way, when the third illuminating means 1c is used, the portion of the substrate without the wiring pattern passes through the illumination light, so that an image with good contrast can be obtained. And the line width of the lower part of a pattern can be detected and measured.

However, the line width of the upper part of a pattern cannot be measured only by the 3rd illumination means 1c. The percentage of the lack of the upper part of the pattern detected in FIG. 6 (a) is 47%.

As mentioned above, the ratio of actual deficiency is 83%, and the magnitude of the detected deficiency is about half smaller than the actual one. This is because the line width at the top of the pattern is not detected correctly.

(3) When illuminating by adding the 1st lighting means 1a (reflection slope) or the 2nd illumination means 1b (transmission slope) to the 3rd lighting means 1c (transmission orthogonal).

FIG. 6 (b) shows the case where the first lighting means 1a (reflective inclination) is added to the third lighting means 1c (transmission orthogonal) to illuminate, and FIG. 6 (c) shows the third illumination. It is a case where the 2nd illumination means 1b (transmission inclination) is added to the means 1c (transmission orthogonal).

As shown in FIG.6 (b) (c), the illumination by the 2nd illumination means 1b and the 3rd illumination means 1c to the illumination by the 3rd illumination means 1c (transmission orthogonal). It is considered that by adding, the line width at the bottom and the line width at the top can be detected.

However, in the case of Fig. 6 (b), the size of the lack of the upper part of the pattern is 64%, and in the case of Fig. 6 (c), the size of the lack of the upper part of the pattern is detected as 55%. In any case, the magnitude of the deficiency is closer to the correct value (83%) than in the case of only the third illumination means 1c (transmission orthogonality) in Fig. 6A, but it is not sufficient.

(4) When illuminating by adding the 1st lighting means 1a (reflection slope) and the 2nd illumination means 1b (transmission slope) to the 3rd lighting means 1c (transmission orthogonal).

6 (d) shows the entirety of the third lighting means 1c (transmission orthogonal), the first lighting means 1a (reflection inclination), and the second lighting means 1b (transmission inclination). In the case of lighting at the same time. The magnitude | size of a lack which is detected is 73%, and is detected by the value closest to the ratio of actual lack. Moreover, the line width of the lower part and the upper part was also able to detect more clearly compared with the case of said (3).

In addition, as will be described later, in the case of illumination of only the third lighting means 1c (transmission orthogonal), both the side surfaces and the upper surface of the pattern are displayed black (dark), and thus the first lighting means 1a (reflection) When the illumination light from the inclination) or the illumination light from the second illumination means 1b (transmission inclination) is added, the side surface of the pattern becomes slightly brighter. Thereby, the upper part of a pattern and the side surface of a pattern can be distinguished, and it becomes possible to detect the line width of an upper part.

FIG. 6 (e) is an enlarged schematic view of an image of a portion lacking (d). Here, the lower portion of the wiring pattern has a width of 20 µm, an upper width of 16 µm, and a side surface having a width of 2 µm. The case is shown and as shown in the same figure, the side part of a pattern becomes slightly brighter than the upper part of a pattern, and can obtain | require the width of a lower part of a pattern from this.

6 (a) to 6 (e) schematically show an image, the image captured by the imaging means 1 is image-processed by the control unit 4, and is lacking based on the luminance of each pixel. By calculating the magnitude of, the magnitude of the lack can be measured.

As described above, by simultaneously performing the first, second, and third illumination, the shape of the upper part of the pattern and the lower part of the pattern can be detected relatively clearly by one measurement, thereby detecting the defect of the pattern. It becomes possible.

In addition, the cross-sectional area can also be obtained by detecting the line width of the lower part of the pattern and the line width of the upper part simultaneously.

In the case of Fig. 6D, when the line width was calculated based on the luminance of each pixel of the picked-up image, the line width at the bottom was about 20 µm, and the line width at the top of the portion where the lack was found was about 4 µm.

Therefore, the cross-sectional area of the portion where the lack occurs is (20 µm + 4 µm) x pattern height x 1/2. In addition, since the height of a pattern cannot be calculated | required from the image of FIG. 6, a design value is substituted.

In the control unit 4 of the apparatus, the lower limit of the cross-sectional area allowed from the current value flowing in the pattern is input in advance. The control part 4 compares the cross-sectional area of the part lacking in the pattern obtained by the said calculation with the lower limit of this cross-sectional area, and makes the pattern defective when it is smaller than a lower limit.

The reason why the line width of the lower part of the pattern and the line width of the upper part can be detected simultaneously by simultaneously performing the first, second, and third illumination can be considered as follows.

This will be described with reference to FIG. 7.

The line width of the lower part of a pattern is detected by the illumination light 3 from the 3rd illumination means 1c (transmission orthogonal).

In addition to this, the illumination light 1 from the first illumination means 1a (reflection slope) and the illumination light 2 from the second illumination means 1b (transmission slope) enter. In addition, illumination light 1 from the 1st lighting means 1a and illumination light 2 from the 2nd lighting means 1b are shown so that it may inject from left and right in FIG. , Light is incident on the pattern from 360 degrees in all directions.

The side of the actual pattern is not a smooth surface, but many fine irregularities. Therefore, the illumination light 1 from the 1st illumination means 1a and the illumination light 2 from the 2nd illumination means 1b are diffusely reflected from the side surface of this pattern, and the one part is image pickup means 11 Enters into. Thus, the side of the pattern is picked up slightly brighter than the top of the pattern.

That is, in the case of illumination of only the third lighting means 1c (transmission orthogonal), both the side surfaces and the upper surface of the pattern are displayed in black (dark), and thus from the first lighting means 1a (reflective inclination) The addition of the illumination light i and the illumination light ii from the second illumination means 1b (transmission inclination) makes the side of the pattern slightly brighter, making it possible to distinguish the top of the pattern from the side of the pattern. Therefore, the shape of the upper part of the pattern becomes clear, and the line width can be detected.

By the above, the shape of the lower part of a pattern, and the shape of an upper part can be detected simultaneously.

FIG. 8: is a figure which shows the experiment result for obtaining the optimal angle of the illumination light of the 1st illumination means 1a and the 2nd illumination means 1b.

The illuminating means 30 illuminating the TAB tape 5 is moved from the side opposite the side on which the pattern is formed to the side on which the pattern is formed, so that the change in the brightness of the side surface of the sample pattern is captured in the image. Measured by.

As shown in Fig. 8A, the illumination means 30 is 0 ° at a position where the illumination light is incident orthogonally from the side opposite to the side on which the pattern is formed (that is, the position of the third illumination means). It measured by moving to the position of 160 degrees toward the side in which the pattern is formed.

In this experiment, since it is difficult to change the incident angle of the illumination light emitted from the annular illumination means, the LED is placed on both sides of the inspection region in the longitudinal direction, and the LED is moved by moving the LED as shown in FIG. 8. The angle of incidence on the TAB tape was changed. Here, the electric current of 70 mA was made to flow through the LED which arrange | positioned the chip | tip in one row as the illumination means 30. As shown to FIG.

The results are shown in Fig. 8B. The horizontal axis is the angle (°) of the lighting means, and the vertical axis is the brightness (arbitrary unit) of the side of the pattern. As shown in the figure, the side surface of a pattern becomes bright when it illuminates in the range of about 30 degrees-60 degrees, and when illuminating more than 120 degrees. The brighter the side of the pattern is, the clearer the boundary with the upper part of the pattern is, which is suitable as the position of the lighting means.

Therefore, the 1st illumination means 1a sets so that the incidence angle of illumination light may be in the range of 120 degrees-160 degrees. Moreover, the 2nd illumination means 1b sets so that the incidence angle of illumination light may be in a range of 30 degrees-60 degrees.

1 is a block diagram of a wiring pattern inspection apparatus of an embodiment of the present invention.

FIG. 2 is an enlarged perspective view of the inspection unit of FIG. 1. FIG.

3 is a cross-sectional view of the inspection part of FIG. 1 taken along the length direction of the TAB tape.

4 is a diagram illustrating a specific configuration example of the first lighting means 1a and the second lighting means 1b formed in an annular shape.

5 is a diagram schematically illustrating a pattern of a sample to be inspected.

FIG. 6 is a diagram schematically showing an image obtained when the combination of the lighting means is changed and the sample of FIG. 5 is imaged.

It is a figure explaining the reason why the line width of the lower part of a pattern and the line width of an upper part can be detected simultaneously by simultaneously performing 1st, 2nd, and 3rd illumination.

FIG. 8 is a diagram showing experimental results for obtaining an optimal angle of illumination light of the first lighting means 1a and the second lighting means 1b.

9 is a diagram illustrating a cross-sectional shape of a wiring pattern formed on a substrate.

<Explanation of symbols for the main parts of the drawings>

1: inspection unit 1a: first lighting means

1b: second lighting means 1c: third lighting means

2: scanning means 3: marker portion

4: control unit 5: TAB tape

6: inspection pattern 10a: LED

10b: prism sheet 10c: diffuser plate

11 imaging means 12 support member

20 tape transfer mechanism 21 unwinding reel

22: reel reel 30: lighting means

Claims (1)

In the wiring pattern inspection apparatus which determines the quality of the said pattern based on the image image which irradiated illumination light to the wiring pattern formed on the light transmissive board | substrate, First illumination means for irradiating the illumination light at an angle to the inspection region at an angle from the side where the wiring pattern of the substrate is formed; Second illumination means for irradiating the light transmissive substrate so that the illumination light is obliquely incident on the inspection region from the side opposite to the side on which the wiring pattern of the substrate is formed; Third illumination means for irradiating the illumination light so as to be incident orthogonally to the inspection area from the side opposite to the side where the wiring pattern of the substrate is formed; Imaging means provided on the side on which the wiring pattern of the substrate is formed; And control means for controlling illumination of the first and second lighting means and the third lighting means, The said control means performs illumination by the said 1st, 2nd, 3rd illumination means simultaneously with respect to the said board | substrate, The said imaging means image | photographs the wiring pattern simultaneously illuminated by the said 1st, 2nd, 3rd illumination means, The wiring pattern inspection apparatus characterized by the above-mentioned.

Images