TW201428279A - Appearance inspection device, and appearance inspection method - Google Patents

Abstract

To allow for detection of defects arising from various causes. An appearance inspection device (100), which is to detect defects by illuminating a sample (S) and inspecting the appearance of the sample (S) from the acquired image data, comprising: a sample stage (110) configured to receive the sample (S); and a microscope (12) to observe the sample (S); a first illumination device (130) including a first light source (131) to irradiate illumination light on the sample (S) so as to make the illumination light irradiate from the viewing direction of the microscope (120); a second illumination device (150) including a second light source (151) to irradiate illumination light on the sample (S) from an oblique direction; a color camera (140) to photograph the image of sample (S) that is under the microscope (120) and irradiated by the aforementioned illumination devices, and to output the color image data; and a processing device (160), based on the color image data to inspect the appearance of the sample (S). The first illumination device (130) and the second illumination device (150) are respectively provided with a first wavelength selection mechanism (132) and a second wavelength selection mechanism (152) for irradiating illumination light of pre-specified wavelength ranges on the sample (S) in accordance with the cause of defects to be inspected.

Description

Visual inspection device and visual inspection method

The present invention relates to an appearance inspection device and an appearance inspection method for inspecting an appearance by imaging an semiconductor wafer or the like with an image pickup element.

Conventionally, a semiconductor wafer or the like is visually inspected, that is, the appearance of the sample is inspected, and defects such as a circuit formed on the surface are detected. In such an appearance inspection, the sample is illuminated with white light, and the state of the surface is imaged by, for example, a color image pickup device including a CCD image sensor, and the image data obtained is subjected to image processing to detect a defective portion. In such an appearance inspection apparatus, in order to improve the inspection accuracy, it takes a lot of thought.

Patent Document 1 discloses an appearance inspection method characterized in that three point lights each having a complementary color relationship are perpendicular to each other in a three-direction angle of 120 degrees with respect to an inspection surface that is obliquely different from each other. The illumination surface is illuminated so as to overlap each other, so that the three-dimensional object on the surface to be inspected is caused by the shadow connection caused by the three point lights, and the degree of connection of the XY coordinates of the shadow is investigated, and it is determined that Defects or noise.

Further, Patent Document 2 discloses a giant inspection (macro) The inspection apparatus includes: a illuminating device for jumbo inspection, a light source that emits coherent light; and a supporting means for supporting a substrate on which a fine processed surface of a predetermined pattern is formed; and a determining means, The diffracted light on the surface to be processed determines whether the pattern formed on the substrate is deformed and does not conform to the prescribed pattern. In this apparatus, the illuminating device for jumbo inspection is configured by irradiating a device containing light of two-color coherent light having a complementary color relationship. In the illuminating device for jumbo inspection, the coherent light is irradiated at a predetermined angle with respect to the finely processed surface of the supporting means.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 2914967

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2001-141657

However, the conventional visual inspection device can detect defects in the surface shape of the sample such as irregularities or scratches on the surface, but it is difficult to detect other defects, which is a problem. That is, a representative example is the presence or absence of a protective film of a polyimide resin, and it is difficult to detect a transparent material. For example, a representative example is such as discrimination between an Au film and a Cu film, and it is difficult to detect a difference in film thickness state such as a color difference of a homochromatic material or a detection film.

The present invention has been developed in view of the above problems, and aims to Provided is an appearance inspection device and an appearance inspection method capable of detecting differences or defects of various materials.

In order to solve the above problems, the visual inspection device according to the present invention includes: a sample stage that is provided with a sample; and an illumination device that includes a light source to illuminate the sample with illumination light; and an imaging device that illuminates the illumination device by the illumination device The sample is imaged and outputted with color image data; and the inspection processing unit checks the appearance of the sample according to the color image data; the appearance inspection device is characterized in that the illumination device is based on the cause of the defect to be inspected. Illumination light of a predetermined specific wavelength region is irradiated to the aforementioned sample.

Similarly, in order to solve the above problems, the visual inspection method of the present invention is characterized in that the sample to be inspected is irradiated with illumination light of a predetermined wavelength region in accordance with the cause of the defect to be inspected, and is obtained by an imaging means. The sample was examined as the color image data, and the appearance of the sample was examined based on the color image data.

According to the present invention, the illuminating device irradiates the illuminating light of a specific wavelength region set in advance in accordance with the type of the defect to be detected, so that various defects can be easily detected in addition to the surface shape of the sample.

10‧‧‧Substrate

12‧‧‧ film

13‧‧‧ plating film

14‧‧‧ plating film

20‧‧‧ camera

100‧‧‧ appearance inspection device

110‧‧‧Testing table

120‧‧‧Microscope

121‧‧‧Spectroscope

130‧‧‧1st lighting device

131‧‧‧first light source

132‧‧‧1st wavelength selection mechanism

133‧‧‧round plate members

134‧‧‧Rotary drive mechanism

140‧‧‧Color camera

150‧‧‧2nd lighting device

151‧‧‧2nd light source

152‧‧‧2nd wavelength selection mechanism

153‧‧‧round plate members

154‧‧‧Rotary drive mechanism

155‧‧‧Lighting means

156‧‧‧ Ring lighting means

160‧‧‧Processing device

161‧‧‧Processing device body

162‧‧‧ Input device

163‧‧‧Image display device

200‧‧‧ appearance inspection device

230‧‧‧Lighting device

S‧‧‧ samples

Fig. 1 is a schematic explanatory view of a visual inspection device and an appearance inspection method according to the present invention.

Fig. 2 is a schematic diagram showing the principle of the visual inspection device and the visual inspection method of the present invention.

Fig. 3 is a schematic diagram showing the principle of the visual inspection device and the visual inspection method of the present invention.

Fig. 4 is a schematic view showing a schematic configuration of an appearance inspection device according to a first embodiment of the present invention.

Fig. 5 is a schematic block diagram showing the configuration of the same visual inspection device.

Fig. 6 is a flow chart showing the operation of the same appearance inspection device.

[Fig. 7] A schematic model diagram of image data acquired by an imaging device and image data subjected to emphasis processing.

8 is a schematic model diagram of image data acquired by an imaging device and image data subjected to emphasis processing.

Fig. 9 is a schematic model diagram of an appearance inspection device according to a second embodiment.

Before explaining the present embodiment, the principle of the visual inspection of the present invention will be described.

1 to 3 are schematic diagrams showing the principle of the visual inspection device and the visual inspection method of the present invention. Figure 1 illustrates the change in reflected light caused by the difference in film thickness. When a film having a predetermined thickness is formed on the substrate 10 In the case of a good product, for example, if the sample 11 is illuminated by the orange illumination source 21 through a beam splitter 22 (coaxial epi-illumination), the green reflected light can be imaged by the imaging device 20 (Fig. 1 (a )). On the other hand, when a defective product such as the film 12 having a predetermined thickness is formed on the substrate 10, if the sample is illuminated by orange illumination, yellow light can be observed by the imaging device 20 (FIG. 1) (b)). The wavelength region (color) of the illumination light used for the inspection can be determined according to the material and thickness to be inspected.

Figure 2 illustrates the reflected light changes caused by the difference in material. When a plating film 13 of a predetermined material (for example, aluminum) is formed on the substrate 10, for example, blue light can be observed by the imaging device 20 (Fig. 2(a)). . On the other hand, when a defective product such as a plating film 14 of a different material (for example, copper) is formed on the substrate 10, orange light can be observed by the imaging device 20 by blue illumination light (FIG. 2). (b)). The wavelength region (color) of the illumination light used for the inspection can be determined according to the material to be inspected.

Figure 3 shows the reflected light changes caused by plating surface defects Chemical. In the case where the plating film 14 is normally formed on the substrate 10, orange light can be observed by the image pickup device 20 by, for example, green illumination (Fig. 3(a)). On the other hand, when a defective product such as a plating film is not formed on the substrate 10, green light can be observed by the imaging device 20 by green illumination (FIG. 3(b)). The wavelength region (color) of the illumination light used for the inspection can be determined according to the plating material or the substrate material to be inspected.

To outline the description, in the visual inspection of the present invention, it is The sample to be inspected is irradiated with illumination light of a predetermined color wavelength region, and an image obtained by the imaging means is used as color image data, and the appearance of the sample is inspected based on the color image data to detect the type of defect (material, reflection). Rate, transmittance, shape). Even if the inspection object is an appearance that is difficult to detect under white light, such as detection of a transparent material (for example, presence or absence of a polyimide film), detection of a homochromatic material (for example, discrimination between Au and Cu films), and detection of a difference in film thickness state In the case of (for example, a thick film thickness), color image data can be obtained by using illumination light of a predetermined wavelength region, thereby checking. In general, materials are known to have wavelengths that are easily absorbed, so this property is utilized. That is to say, in the present invention, the illumination of a specific wavelength region (color) is used to detect the transparent material and the discrimination of the same color dissimilar material. Further, the difference in film thickness is irradiated with illumination in a specific wavelength region, and is determined from a color that changes due to the absorption wavelength of the film and a color that changes in thickness due to interference.

In other words, choose the type of defect for the purpose of the test. The wavelength region of the light source is selected and illuminated, and is photographed by a camera. In this way, the product is illuminated by light in a wavelength region corresponding to the cause of the appearance defect to be detected, and the defective product is detected based on the reflected light. In this way, the detection of defects to be inspected can be improved, and excessive detection can be reduced.

<First embodiment>

Hereinafter, an appearance inspection device according to a first embodiment of the present invention will be described. Figure 4 is a schematic configuration diagram of a visual inspection device according to a first embodiment of the present invention, FIG. 5 is a schematic block diagram showing the configuration of the same appearance inspection device, and FIG. 6 is a flow chart showing the operation of the same appearance inspection device.

First, the configuration of the visual inspection device 100 will be described. 1st The visual inspection device 100 according to the embodiment includes a sample stage 110 on which a sample is placed, a microscope 120 disposed above the sample stage 110, and a first illumination device 130 that illuminates the first illumination light along the optical axis of the microscope 120. The sample S; and the color camera 140, that is, the image pickup means; and the second illumination device 150 are disposed between the sample stage 110 and the first illumination device 130; and the processing device 160 is an inspection processing unit configured by a computer. The control of each device and the analysis of the image data acquired by the color camera 140 are performed.

The sample table 110 carries the sample S according to the processing device 160 By controlling, the sample S can be moved in the horizontal direction (X, Y), the vertical direction (Z), and the rotation direction (θ). The moving mechanism can employ a mechanism using a screw mechanism or a piezoelectric element. The microscope 120 is provided with an optical system for imaging an image of the sample S on the imaging surface of the color camera 140. Further, the microscope 120 includes a beam splitter 121 that reflects the illumination light from the first illumination device 130 in the optical axis direction. The image obtained by the microscope 120 may be an enlarged image or an equal magnification image.

The first illumination device 130 is composed of a first light source 131 composed of a xenon lamp, a halogen lamp, or the like, and a first wavelength selection mechanism 132. The first wavelength selecting means 132 is composed of a disk member 133 in which filters (color filters) of various transmission wavelength regions are arranged on the circumference, and a rotation drive mechanism 134, that is, a filter selecting device. The disc member 133 is at Rotating under the control of the processing device 160; In the present example, in the disk member 133, a plurality of sheets (for example, seven sheets) through which light of different wavelength regions are transmitted are transmitted through the filter, that is, the color filter, and the through-hole through which the white light from the first light source 131 passes directly ( One hole in the legend is not drawn, and is arranged on the circumference. The disk member 133 is rotated by the rotation driving mechanism 134 to stop at a predetermined position, so that light of a desired frequency region or white light can be irradiated to the sample S along the optical axis. Further, of course, the number of the perforations or the color filters is not limited to the above.

The color camera 140 is equipped with a CCD (Charge Coupled) Device) An imaging element such as an imaging element or a CMOS (Complementary Metal Oxide Semiconductor) imaging element, which images the sample S and outputs the image data.

The second lighting device 150 is like the first lighting device 130 In general, a second light source 151 including a xenon lamp, a halogen lamp, and the like, and a second wavelength selecting mechanism 152 including a disk member 153 and a rotation driving mechanism 154 are provided. Further, the ring illumination means 156 is configured to emit an annular illumination light, for example, an illumination means for illuminating the illumination light from a predetermined angle with respect to the optical axis with respect to the imaging region of the sample S; and a light guiding means 155. The light from the second wavelength selection mechanism 152 is guided to the ring illumination means 156. In addition to the object that emits the ring illumination, the second illumination device 150 can also be illuminated by using a linear light-emitting portion.

The ring illumination means 156 shown in this example is made of a ring-shaped transparent A conical table consisting of bright material and having a side inside which is inclined toward the sample. The hole is shaped such that the side of the hole is inclined as a member for directing the light from the ring illumination means 156 toward the sample S. By the ring illumination means 156, the light from the second illumination device 150 is directed toward the observation region of the sample S in an annular shape and irradiated obliquely upward.

In addition, the first illuminating device 130 and the second illuminating device 150 As the light source to be used, in addition to the above-described constituent materials, light sources of various configurations can be used. Further, the first illuminating device 130 and the second illuminating device 150 may be configured by a plurality of light sources that generate light of different wavelength regions and a light source selecting means that selects a light source that illuminates the sample. Further, the illumination device can be configured by a light source that can change the generated wavelength region and a wavelength region changing means that changes the wavelength region of the light generated from the light source.

The processing device 160 is input by the processing device body 161 The device 162, the image display device 163, and the like are configured. The processing device main body 161 is a computer including a CPU, a RAM, a ROM, an HDD, and the like. In the processing apparatus main body 161, the CPU executes an application software program stored in a ROM, an HDD or the like, and performs control of each part of the visual inspection apparatus 100 and processing of image data acquired by the color camera 140 to perform visual inspection. The input device 162 includes a keyboard, a mouse, and the like, and the operator inputs an instruction to the processing device 160. The image display device 163 is composed of a liquid crystal display, a CRT, or the like, and displays image data from the color camera 140, an image subjected to image processing, an inspection result, and the like. Further, the touch panel of the input device 162 can be disposed on the image display device 163.

Such an appearance inspection device 100 is inspected in the following manner Sample appearance. Fig. 6 is a flow chart showing the operation of the same visual inspection device. for When the visual inspection of the sample is performed, the wavelength region of the illumination light generated by the first illumination device 130 and the second illumination device 150 is first selected (step S1, step S2). This selection is made from the input device 162 of the processing device 160 in accordance with the type of defect to be detected. By the designation from the processing device 160, the rotation driving mechanism 134 of the first wavelength selecting means 132 rotates the disk member 133, and the light from the first light source 131 passes through the predetermined color filter or the transmission hole. Similarly to the second illumination device 150, the rotation driving mechanism 154 rotates the disk member 153 to pass the light from the second light source 151 through the predetermined color filter or the transmission hole.

Next, the sample station 110 is controlled by the processing device 160, and The sample S moves to the observation position (step S3). This movement can be specified by the operator from the input device 162 in addition to the information previously set in the processing device 160.

Next, the observation area is imaged by the color camera 140. The color image data is acquired (step S4).

Then, the image data obtained by the processing device 160 will be obtained. Image processing is performed, and a defect is detected from the image (step S6). The detection of the defect can be performed by comparing the reference image data obtained as a reference from the good sample with the acquired image data. Further, in the case of checking a reverse pattern or a non-pattern surface, it can be performed by an autocorrelation inspection. The autocorrelation inspection is performed in the case of repeating the pattern by comparing the reverse patterns in the image data of the sample by one pitch (or n pitch). Moreover, image processing can be performed before image data comparison for defect detection, The image processing includes an emphasis processing for emphasizing a specific wavelength region of the imaged color image data, and extracting the specific wavelength region.

Next, an example of the inspection result will be described. Figure 7 and Figure 8 show A schematic model diagram of the image data acquired by the imaging device and the image data subjected to the emphasis processing. 7(d) is a model diagram corresponding to the AB line cross section in FIGS. 7(a), (b), and (c), and FIG. 8(d) is equivalent to FIG. 8(a), (b), ( c) Model diagram of the section of the AB line. The first case is to check for defects caused by the overflow of transparent materials. In this example, as shown in FIG. 7(d), the sample S of the sample S has overflowed the transparent protective film. If the sample is illuminated only with white light, a transparent protective film is not visible (Fig. 7(a)). In the visual inspection device 100 according to the first embodiment, when the first illumination device 130 is irradiated with white illumination, the second illumination device 150 is irradiated with blue illumination, and the color camera 140 is used for imaging, the blue component is protected by the protective film. The reflection of the image data of the discriminable protective film can be obtained (Fig. 7(b)). The case of the overflow defect of the transparent protective film is only slightly visible (Fig. 7(b)). Further, when the blue color is extracted from the material and the image processing is emphasized, the protective film is more vividly floated and can be easily detected (Fig. 7(c)). The case of the overflow defect of the transparent protective film can be clearly seen (Fig. 7(c)).

The second case examined defects of the same color material. In this case, In the sample S, as shown in Fig. 8(d), erosion of the dissimilar material occurred. If the sample is illuminated only with white light, the dissimilar material is not visible (Fig. 8(a)). In the visual inspection device 100 according to the first embodiment, white illumination is emitted from the first illumination device 130, and blue illumination is emitted from the second illumination device 150. The color illumination is imaged by the color camera 140, and image data of the distinguishable protective film can be obtained (Fig. 8(b)). The situation of erosion defects is only slightly visible (Fig. 8(b)). Further, when the blue color is extracted from the material and the image processing is emphasized, the protective film is more vividly floated and can be easily detected (Fig. 8(c)). The situation of erosion defects can be clearly seen (Fig. 8(c)).

As described above, the appearance according to the first embodiment of the present invention The inspection device can easily detect surface differences and defects on the surface.

<Second embodiment>

Next, an appearance inspection device according to a second embodiment of the present invention will be described. Fig. 9 is a schematic view showing the appearance inspection apparatus of the second embodiment. The visual inspection device 200 includes only one illumination device 230 as an illumination device. The other configuration is the same as that of the visual inspection device 100 of the first embodiment. In the illumination device 230, the sample S is irradiated with illumination light from the optical axis direction of the microscope.

In the visual inspection device 200 of the second embodiment, the matching is performed. The wavelength region of the illumination light from the illumination device 230 is selected for the cause of the defect to be detected. Therefore, in the appearance inspection device 200 according to the second embodiment, as in the appearance inspection device 100 of the first embodiment, various defects such as material difference, film thickness, and presence or absence of plating can be easily detected.

100‧‧‧ appearance inspection device

110‧‧‧Testing table

120‧‧‧Microscope

121‧‧‧Spectroscope

130‧‧‧1st lighting device

131‧‧‧first light source

132‧‧‧1st wavelength selection mechanism

133‧‧‧round plate members

134‧‧‧Rotary drive mechanism

140‧‧‧Color camera

150‧‧‧2nd lighting device

151‧‧‧2nd light source

152‧‧‧2nd wavelength selection mechanism

153‧‧‧round plate members

154‧‧‧Rotary drive mechanism

155‧‧‧Lighting means

156‧‧‧ Ring lighting means

160‧‧‧Processing device

161‧‧‧Processing device body

162‧‧‧ Input device

163‧‧‧Image display device

S‧‧‧ samples

Claims (11)

An appearance inspection device includes: a sample stage that arranges a sample; and an illumination device that includes a light source to irradiate illumination light to the sample; and an imaging device that images the sample illuminated by the illumination device and outputs a color map The image processing unit and the inspection processing unit check the appearance of the sample according to the color image data; the visual inspection device is characterized in that the illumination device is set to a specific wavelength region according to the cause of the defect to be inspected. The illumination light is irradiated to the aforementioned sample. The visual inspection device according to claim 1, wherein the illumination device includes a wavelength selection mechanism including: a plurality of transparent filter filters for transmitting light of different wavelength regions; and a filter selection device; The transmissive filter selected from the plurality of filter filters is disposed in the optical path from the light source to the sample. The visual inspection device according to claim 1, wherein the illumination device includes: a plurality of light sources for generating light of different wavelength regions; and a light source selection means for selecting a light source for illuminating the sample. The visual inspection device according to claim 1, wherein the illumination device includes a wavelength region changing means for changing a wavelength region of light, and the wavelength of light illuminated by the illumination device is variable. The visual inspection device according to any one of claims 1 to 4, wherein the illumination device includes a plurality of illumination devices that are irradiated to the sample The corners are different. The visual inspection device according to claim 5, wherein the illumination device that irradiates the illumination light to the sample from a direction different from the imaging direction of the imaging device includes a ring disposed above the observation region of the sample. The illumination light is emitted. The visual inspection device according to any one of claims 1 to 6, wherein the inspection processing unit is configured to apply color image data of the sample to be imaged and a reference color image data as a reference for the sample. Compare them for visual inspection. The visual inspection device according to any one of claims 1 to 6, wherein the inspection processing unit detects the color image data of the sample to be imaged by autocorrelation. The repeated images of the samples are compared with each other for visual inspection. The visual inspection device according to claim 7, wherein the inspection processing unit includes an image processing means for performing image processing for including a specific wavelength region of the color image data of the sample to be imaged. Emphasis is placed on the processing of extracting and extracting the specific wavelength region. An appearance inspection method is characterized in that, for a sample to be inspected, illumination light of a predetermined wavelength region is irradiated according to a cause of a defect to be inspected, and the sample is obtained by an imaging means as color image data, The color image data described above was used to examine the appearance of the aforementioned sample. Such as the visual inspection method of claim 10, In the middle, an emphasis processing for emphasizing a specific wavelength region of the color image data of the sample to be imaged is applied.