CN114077120A

CN114077120A - Lighting device

Info

Publication number: CN114077120A
Application number: CN202010742518.8A
Authority: CN
Inventors: 萧贤德; 王宣復
Original assignee: Huayang Precision Machinery Co ltd
Current assignee: Huayang Precision Machinery Co ltd
Priority date: 2020-07-29
Filing date: 2020-07-29
Publication date: 2022-02-22

Abstract

The invention discloses a lighting device for providing illumination to an illumination area, comprising at least two lighting devices. At least two lighting devices are disposed around the lighting area and face each other. Each of the at least two illumination devices is used for vertically converging a plurality of collimated light beams which are horizontally arranged into parallel light and then horizontally focusing the parallel light into illumination light to illuminate an illumination area.

Description

Lighting device

Technical Field

The present invention relates to a vision inspection or scanning system, and in particular to an illumination device for a vision inspection or scanning system.

Background

As semiconductor technology advances, the structure, size or circuitry of semiconductor materials (e.g., wafers) becomes finer and inspection of the processes at various stages becomes more and more important, including inspection of the semiconductor materials, as well as materials or devices used in the processes, such as masks.

The known dark area inspection technology is to irradiate illumination light (projection) on the semiconductor material or the mask and then to capture an image by an image capturing device, so that the dust or foreign matter on the semiconductor material or the mask is bright on the image and is found.

At present, when the illumination light irradiates the inspected area of the photomask, the tiny dust or foreign matter and the pattern in the range of the inspected area are all illuminated, but because the reflectivity of the pattern is higher than that of the tiny dust or foreign matter, the reflected light intensity of the pattern is larger than that of the tiny dust or foreign matter, which is not favorable for image capture and inspection operation.

In order to avoid the problems caused by the single light source, the illumination light currently includes illumination light composed of annularly arranged laser beams, as shown in fig. 6, fig. 6 is a diagram of the light receiving angles of eight laser beams projected on an object through the annular arrangement, and it can be seen that the laser beams are single-angle approximately collimated beams, that is, the angles projected by the laser beams can generate high-intensity illumination, and the intervals between the laser beams are almost without illumination light. Although the illumination mode can increase the light receiving angle of the inspected area, it is still insufficient to uniformly distribute the illumination light in the range of 360 degrees, so that when the image capturing device captures images, the reflected light intensity of the pattern in the inspected area may still be larger than the reflected light intensity of tiny dust or foreign matter in a specific angle, which is not favorable for image capturing and inspection.

Disclosure of Invention

The invention aims to provide an illuminating device which can provide illumination with more uniform angle and high intensity so as to clearly illuminate foreign matters or defects and clearly identify the positions and the sizes of the foreign matters or the defects.

In order to achieve the above object, the illumination apparatus of the present invention is used for illuminating an illumination area, and the illumination apparatus includes at least two illumination devices. At least two lighting devices are disposed around the lighting area and face each other. Each of the at least two illumination devices is used for vertically converging a plurality of collimated light beams which are horizontally arranged into parallel light and then horizontally focusing the parallel light into illumination light to illuminate an illumination area.

Thus, the illumination device of the invention can provide multi-angle illumination through the illumination light focused by a plurality of collimated light beams, and can provide illumination with high illumination intensity for an illumination area.

The parallel light is a line light source, and the illuminating light is a point light source.

Each of the lighting devices includes a light emitting unit, a microlens array, a first lens and a second lens, the light emitting unit includes a plurality of light emitting elements to generate a plurality of divergent lights, the microlens array is located between the light emitting unit and the first lens and includes a plurality of microlenses, the divergent lights pass through the microlenses one by one to output the collimated light beams, the collimated light beams pass through the first lens to output the parallel lights in a vertically converging manner, and the second lens faces the first lens and allows the parallel lights to pass through and horizontally focuses and outputs the illumination lights.

Wherein the plurality of light emitting elements and the plurality of microlenses are arranged in parallel.

The illumination light of the at least two illumination devices comprises a blue visible light and a green visible light.

In order to achieve the above object, the illumination device of the present invention is used for illuminating an illumination area. The lighting device comprises a plurality of lighting means. A plurality of lighting devices are circumferentially disposed about the lighting zone. Each of the plurality of illuminating devices is used for vertically converging a plurality of collimated light beams which are horizontally arranged into parallel light and then horizontally focusing the parallel light into illuminating light to illuminate an illuminating area.

In this way, the illumination device of the present invention can provide illumination at more angles and brightness through the plurality of collimated light beams, and provide illumination at a wider angle through the illumination device surrounding the illumination area.

Each of the lighting devices includes a light emitting unit, a microlens array, a first lens and a second lens, the light emitting unit includes a plurality of light emitting elements to generate a plurality of divergent lights, the microlens array is located between the light emitting unit and the first lens and includes a plurality of microlenses, the plurality of divergent lights pass through the plurality of microlenses one to output the plurality of collimated light beams, the plurality of collimated light beams pass through the first lens to output the parallel lights in a vertically converging manner, and the second lens faces the first lens and allows the parallel lights to pass through and output the illumination lights in a horizontally converging manner.

The detailed construction, composition, characteristics, operation or use of the lighting device provided by the present invention will be described in the following detailed description of the embodiments. However, those skilled in the art should understand that the detailed description and specific examples, while indicating the specific embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

Drawings

Fig. 1 is a schematic view of an illumination apparatus of the present invention applied to a vision scanning system to inspect an object.

Fig. 2 is a schematic top view of an optical structure of one of the illumination devices and illumination light of the illumination apparatus of fig. 1.

Fig. 3 is a side view of the illumination light and the optical structure of one of the illumination devices of the illumination apparatus of fig. 1.

Fig. 4 is a schematic view of the illumination area viewed from the image capturing device of the vision scanning system of fig. 1, and the illumination devices arranged in a ring shape.

Fig. 5 is a graph showing the relationship between the light receiving angle and the light intensity of the object irradiated by the illumination device shown in fig. 4.

Fig. 6 is a graph showing the relationship between the light receiving angle and the light intensity of the object measured by the annular laser beam.

Wherein, the reference numbers:

100 visual scanning system

11,51 Lighting device

13 image taking device

131 first camera

132,134 filter

133 second Camera

135 spectroscope

137,59 imaging area

15,55 illumination area

151 reflection light

17,19,53 lighting device

171 light emitting unit

172 light emitting element

1721 diverging light

173 microlens array

174 microlens

1741 collimating light beam

175 first lens

1751 parallel light

176 second lens

177,57 illuminating light

300 mask

31 glass

32 pattern layer

33: frame

35 film

Detailed Description

The following description is provided to illustrate the components and functions of the lighting device of the present invention with reference to the accompanying drawings. However, the components, dimensions, appearance and illumination range of the illumination device in the drawings are only used for illustrating the technical features of the invention, and the invention is not limited thereto.

As shown in fig. 1, the illumination apparatus of the present invention is often applied to a vision scanning system 100 of a specific manufacturing process, and the vision scanning system 100 detects the state of the image-mapped surface of the object by taking a partial image of the surface of the object and checking the image by a known image processing technique, and marks information on the object, such as the position of dust, dirt, or defect on the object.

The inspected object is an inspection environment such as glass, wafer, and mask. In the following description of the embodiment, the mask 300 is taken as an example of the object to be inspected. The mask 300 includes a glass 31, a frame 33, and a film 35, and a surface of the glass 31 includes a pattern layer 32. The frame 33 is connected to the glass 31 and frames the pattern layer 32. The film 35 is connected to the frame 33 to prevent foreign substances (e.g., dust) from adhering to the pattern layer 32. The test surface is a pattern layer 32.

The vision scanning system 100 includes an illumination device 11 and an image capturing device 13. The illumination device 11 is configured to provide illumination to an illumination area 15 of the patterned layer 32, the illumination area 15 being a partial area of the patterned layer 32. The lighting device 11 comprises two lighting means 17, 19. Two

lighting devices

17,19 are arranged around the lighting area 15 and face each other. The image capturing device 13 is used for capturing an image of the pattern layer 32 in the image capturing area 137, where the image capturing area 137 is a range where the image capturing device 13 observes the pattern layer 32, as defined by two dotted lines in the figure. The illumination area 15 is substantially smaller than the image capture area 137. The image capturing device 13 captures an image of the illumination area 15 and includes a first camera 131, a second camera 133 and a beam splitter 135.

In this embodiment, the illumination device 17 generates illumination of blue visible light, and the illumination device 19 generates illumination of green visible light. The first camera 131 and the second camera 133 of the image capturing device 13 have

filters

132 and 134, respectively, the filter 132 of the first camera 131 filters blue visible light to receive green visible light, and the filter 134 of the second camera 133 filters green visible light to receive blue visible light. In other embodiments, the

illumination devices

17 and 19 may also be visible light or invisible light with other colors or all the same color, so the illumination light colors of the

illumination devices

17 and 19 are not limited to the embodiment.

In this embodiment, the reflected light 151 illuminated in the illumination area 15 enters the image capturing device 13 and enters the first camera 131 and the second camera 133 through the beam splitter 135 to form corresponding images, and the images are processed by a known image processing technique to identify the state of the pattern layer.

Since the image capture area or illumination area 15 is smaller than the patterned layer 32, in the present embodiment, the illumination area 15 is approximately 10mm by 10mm, and therefore, in order to inspect the entire patterned layer 32, the mask 300 and the vision scanning system 100 are moved relatively, for example, the mask 300 is moved to allow the vision scanning system 100 to inspect the entire patterned layer 32, or the vision scanning system 100 is moved to sequentially inspect the patterned layers 32 of the entire mask 300.

As shown in fig. 2 and 3, the

illumination devices

17 and 19 have the same structure, and the illumination device 17 includes a light emitting unit 171, a microlens array 173, a first lens 175, and a second lens 176, taking the illumination device numbered 17 as an example. The light emitting unit 171 includes a plurality of light emitting elements 172 to generate a plurality of diverging lights 1721, and the light emitting elements 172 may be Light Emitting Diodes (LEDs). The light emitting elements 172 are spaced apart along a horizontal line to provide multiple angles of horizontally arranged light emitting sources. The microlens array 173 is disposed between the light emitting unit 171 and the condensing lens 175, and includes a plurality of microlenses 174, the microlenses 174 are arranged along a horizontal line identical to the arrangement of the light emitting elements 172, and the arrangement of the light emitting elements 172 and the microlenses 174 is parallel to the horizontal line. The diverging light 1721 produced by the light emitting element 172 passes through the microlenses 174 one-to-one to output a horizontally aligned and substantially collimated beam 1741, the collimated beam 1741 being aligned along a horizontal line. The light emitting elements 172 are aligned one-to-one microlenses 174, and the microlenses 174 may be cylindrical. Wherein the collimated beam 1741 is substantially a linear light source. The first lens 175 includes a spherical surface, and the collimated light beam 1741 outputs the parallel light 1751 through the first lens 175 in a vertical convergence, which is a projection range of the first lens 175 limiting the highest and lowest of the parallel light 1751, so that the parallel light 1751 converges to a line light source illumination at a specific height. The second lens 176 faces the first lens 175 and is used for allowing the parallel light 1751 to pass through and horizontally focusing the output illumination light 177, and the illumination light 177 is finally focused into a point light source, so that the illumination light 177 generated by the

illumination devices

17 and 19 can achieve the purposes of multi-angle confocal and brightness increase, namely, the illumination device has the characteristics of high brightness and rich light receiving angles.

Thus, the

illumination device

17,19 of the present invention can provide multi-angle and high brightness illumination by focusing horizontally the illumination light 175 after vertically converging the horizontally aligned collimated light beam 1741 into parallel light 1751.

Fig. 4 is a schematic view of the illumination area viewed by the image capturing device, as shown in fig. 4. The illumination device 51 includes eight illumination devices 53, the eight illumination devices 53 are disposed around the illumination area 55 and surround the illumination area for 360 degrees, the illumination light 57 of the eight illumination devices 53 is disposed in the illumination area 55 to provide multi-angle and high-brightness (light intensity) illumination of the illumination area 55, and the composition and application of each illumination device 53 are the same as those of the illumination device 17, which is not described herein again. The illumination area 55 is within the image capture area 59, and the image capture area 59 is substantially circular. In this way, the illumination device 51 can provide illumination with light rays covering substantially 360 degrees and has a high brightness characteristic.

Fig. 5 is a graph showing the amount of light intensity received by the object of fig. 4, as shown in fig. 5. Because the lighting device of the invention converts the linear light source formed by the multi-angle light emitting source into the focused illumination light, it can be understood from fig. 5 that each lighting device can provide illumination light at a wider angle, so that the light receiving angle of the object is richer, and in addition, the focused illumination light output by each lighting device can output the light intensity of the light emitting element, thereby effectively improving the light intensity received by the surface of the object.

When the dark area inspection is carried out, the illuminating light of the illuminating device can avoid the pattern of the photomask from generating stronger reflected light, and can improve the intensity of the reflected light of the dust or the foreign matters, thereby being more suitable for distinguishing the position, the size and the like of the dust or the foreign matters so as to improve the identification capability of the visual scanning system.

Finally, it is emphasized that the components disclosed in the above embodiments are merely examples and should not be taken as limitations on the scope of the present disclosure, and that other equivalents and modifications may be made thereto and still fall within the scope of the present disclosure.

The present invention is capable of other embodiments, and various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. An illumination apparatus for providing illumination to an illumination region, comprising:

at least two lighting devices are arranged around the lighting area and face each other, and each lighting device vertically converges a plurality of collimated light beams which are horizontally arranged into parallel light and then horizontally focuses the parallel light into lighting light to illuminate the lighting area.

2. The illumination device as recited in claim 1, wherein the parallel light is a line light source and the illumination light is a point light source.

3. The illumination apparatus according to claim 1, wherein each of the illumination devices comprises a light-emitting unit, a micro-lens array, a first lens and a second lens, the light-emitting unit comprises a plurality of light-emitting elements to generate a plurality of divergent lights, the micro-lens array is located between the light-emitting unit and the first lens and comprises a plurality of micro-lenses, the plurality of divergent lights pass through the plurality of micro-lenses one-to-one to output the plurality of collimated light beams, the plurality of collimated light beams output the parallel lights in a vertical convergence through the first lens, and the second lens faces the first lens and passes the parallel lights to output the illumination lights in a horizontal focus.

4. The illumination apparatus according to claim 3, wherein the plurality of light emitting elements and the plurality of microlenses are arranged in parallel.

5. The illumination apparatus according to claim 1, wherein the illumination light of the at least two illumination devices comprises a blue visible light and a green visible light.

6. An illumination apparatus for providing illumination to an illumination region, comprising:

and each illuminating device vertically converges a plurality of collimated light beams which are horizontally arranged into parallel light and then horizontally focuses the parallel light into illuminating light to illuminate the illuminating area.

7. The illumination device as recited in claim 6, wherein the parallel light is a line light source and the illumination light is a point light source.

8. The illumination apparatus according to claim 6, wherein each of the illumination devices comprises a light-emitting unit, a micro-lens array, a first lens and a second lens, the light-emitting unit comprises a plurality of light-emitting elements to generate a plurality of divergent lights, the micro-lens array is located between the light-emitting unit and the first lens and comprises a plurality of micro-lenses, the plurality of divergent lights pass through the plurality of micro-lenses one-to-one to output the plurality of collimated light beams, the plurality of collimated light beams output the parallel lights in a vertical convergence through the first lens, and the second lens faces the first lens and passes the parallel lights to output the illumination lights in a horizontal convergence.

9. The illumination apparatus according to claim 8, wherein the plurality of light emitting elements and the plurality of microlenses are arranged in parallel.