CN115753823A - Wafer defect detection equipment - Google Patents

Abstract

The invention provides a wafer defect detection device which comprises a carrying platform, a light source module, a spectroscope and a light filtering piece. The carrier detects a sample to be detected. The light source module comprises an illumination unit and a semi-transparent mirror. The illumination unit emits detection light. The reflecting surface can reflect the detection light to the sample to be detected, so that the reflected light of the sample to be detected reflecting the detection light passes through the semi-transparent mirror and is divided into a plurality of light splitting light by the light splitter. The plurality of optical filters are configured to pass the plurality of split light beams corresponding to different wavelength bands. The image sensors receive the split light rays to generate a plurality of imaging pictures. Any two of these imaged frames have different contrasts at the corresponding two positions. The image frame with higher contrast can be used to determine whether there is a defect at the position. Compared with the prior art that the light sources with different wavelengths are required to be replaced to individually detect the samples to be detected, the wafer defect inspection equipment can obtain a plurality of imaging pictures with different wave bands by one-time detection, and can effectively save time.

Description

Wafer defect detection equipment

Technical Field

The invention relates to a wafer defect detection device, in particular to a wafer defect detection device with high detection efficiency.

Background

Currently, it is quite common to determine whether a sample to be tested is a good product by Automatic Optical Inspection (AOI). Generally, there are multiple target features on the sample to be tested that need to be confirmed to meet the standard. The contrast of the target feature at the same position on the sample to be measured may also vary corresponding to the detection light of different wavelength bands. Therefore, the appropriate wave bands are respectively selected according to different target features and the shapes (topographies) of the target features, which is beneficial to improving the contrast of an imaging picture and more clearly judging whether the target features corresponding to all the positions meet the standard.

However, if the method is used to obtain a better detection quality, the conventional detection method detects the sample to be detected with light of multiple wave bands respectively, and then an imaging frame with high contrast of each target feature can be obtained. Therefore, as the number of features detected increases, the detection time will increase by a factor, causing a decrease in the efficiency of the automated optical detection.

Disclosure of Invention

The invention is directed to a wafer defect inspection apparatus, which can receive imaging pictures generated by light of various wave bands through one-time inspection, so as to improve the inspection efficiency.

The invention relates to a wafer defect detection device, which is suitable for detecting a sample to be detected and comprises a carrying platform, a light source module, at least one spectroscope, a plurality of light filtering pieces and a plurality of image sensors. The carrier is adapted to carry a sample to be tested. The light source module is arranged corresponding to the carrying platform. The light source module includes a lighting unit and a half mirror. The illumination unit is used for emitting detection light. The half mirror has a reflecting surface. The reflection surface faces the illumination unit and the stage. The reflecting surface is suitable for reflecting the detection light to the sample to be detected so that the reflected light of the reflected detection light of the sample to be detected passes through the semi-transparent mirror. The at least one spectroscope is arranged on one side of the semi-transparent mirror opposite to the carrier and used for receiving the reflected light rays passing through the semi-transparent mirror and separating a plurality of light splitting light rays. The plurality of optical filters are respectively arranged on the optical paths of the light splitting rays, and the optical filters are configured to allow the light splitting rays to pass through a plurality of different wave bands correspondingly. The image sensors are arranged on the light paths of the light splitting rays and are respectively one side of one light filtering piece opposite to the spectroscope, each image sensor receives one light splitting ray to generate an imaging picture, and the images at the same corresponding positions in any two imaging pictures have different contrasts.

Based on the above, the wafer defect inspection apparatus of the present invention can separate and filter out multiple split light beams with different wave bands from the reflected light beam reflected by the sample to be inspected by the arrangement of the beam splitter and the optical filter, and the split light beams are received by the plurality of image sensors to synchronously generate a plurality of imaging pictures. Because the imaged frames have different contrasts at the corresponding positions, the imaged frame with higher contrast can be used for judging whether the position has defects or not. Compared with the prior art that the light sources with different wavelengths are required to be replaced to individually detect the samples to be detected, the wafer defect inspection equipment can obtain a plurality of imaging pictures with different wave bands by one-time detection, thereby effectively saving time and improving the detection efficiency.

Drawings

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

FIG. 1 is a schematic diagram of a wafer defect inspection apparatus according to an embodiment of the present invention;

FIG. 2A is a schematic top view of a sample to be tested;

FIG. 2B is an image of a microscope at position A captured by one of the image sensors;

FIG. 2C is an image of a microscope at position A captured by another image sensor;

FIG. 2D is an image of a microscope at position B captured by an image sensor;

FIG. 2E is an image of a microscope at position B captured by another image sensor;

FIG. 3 is a schematic diagram of a wafer defect inspection apparatus according to another embodiment of the present invention;

fig. 4 is a schematic diagram of a wafer defect inspection apparatus according to another embodiment of the invention.

Description of the reference numerals

100. 100A, 100B wafer defect inspection equipment;

110 is a carrier;

111, a sample to be detected;

120, a light source module;

121, a lighting unit;

122, a semi-transparent mirror;

131. 132, 133 spectroscope;

122R, 131R, 132R, 133R are reflecting surfaces;

151. 152, 153, 154 image sensors;

141. 142, 143, 144, a filter;

161. 162, a light attenuating member;

A. b is position;

l, detecting light;

i1, I2, I3, I4, I5 and I6 are light splitting rays;

ImA, imB, imC and ImD are imaging pictures;

RL1 is reflected light;

RL2, RL3, RL4 and RL5 are used for filtering and reflecting light;

X-Y is rectangular coordinate.

Detailed Description

Reference will now be made in detail to exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings and the description to refer to the same or like parts.

Fig. 1 is a schematic diagram of a wafer defect inspection apparatus according to an embodiment of the invention. Referring to FIG. 1, rectangular coordinates X-Y are provided to facilitate the description of the subsequent components.

As shown in fig. 1, in the present embodiment, the wafer defect detecting apparatus 100 includes a stage 110, a light source module 120, a beam splitter 131, filters 141 and 142, and image sensors 151 and 152. The stage 110 is adapted to carry a sample 111 to be measured. In some embodiments, the sample 111 to be tested is, for example, a semiconductor wafer, but not limited thereto. The light source module 120 is disposed corresponding to the stage 110, and includes an illumination unit 121 and a half-lens 122.

The illumination unit 121 emits the detection light L, and the frequency spectrum of the detection light may be a continuous spectrum. For example, in some embodiments, the spectrum of the detection light L may include at least two of an ultraviolet light band (wavelength range of about 100nm to 380 nm), a violet light band (wavelength range of about 380nm to 450 nm), a blue light band (wavelength range of about 450nm to 495 nm), a green light band (wavelength range of about 495nm to 570 nm), a yellow light band (wavelength range of about 570nm to 590 nm), an orange light band (wavelength range of about 590nm to 620 nm), a red light band (wavelength range of about 620nm to 750 nm), and an infrared light band (wavelength range of about 750nm to 1 mm).

For example, in the present embodiment, the detecting light L includes a red light band (with a wavelength range of about 620nm to 750 nm) and a blue light band (with a wavelength range of about 450nm to 495 nm), but not limited thereto.

In some embodiments, the illumination unit 121 may include, for example, a xenon lamp, a mercury lamp, or a tungsten lamp for a plurality of optical bands. In some embodiments, the illumination unit 121 may include an led chip and a wavelength conversion material disposed on the led chip to provide multi-band light. The led chip may be a blue led chip, and the wavelength conversion material may be a green phosphor layer, a yellow phosphor layer, or a red phosphor layer, but the invention is not limited thereto.

In the present embodiment, the half mirror 122 is used to reflect part of the light and transmit part of the light. Specifically, the half mirror 122 is disposed opposite to the illumination unit 121 and is located on the optical path of the detection light L. The reflection surface 122R of the half mirror 122 faces the illumination unit 121 and the stage 110, and is used for reflecting the detection light L to the observation surface on the sample 111 to be measured. The illumination unit 121 and the sample 111 are located on the same side of the half-lens 122, and the reflection surface 122R is used for changing the direction of the detection light L.

In the present embodiment, the direction of the detection light L emitted by the illumination unit 121 is, for example, parallel to the X-axis direction, the direction of the detection light L reflected by the reflection surface 122R is parallel to the Y-axis (-Y) direction, and the reflected light RL1 reflected by the sample to be measured 111 is parallel to the Y-axis (+ Y) direction, so that the detection light L reflected by the reflection surface 122R and the reflected light RL1 reflected by the sample to be measured 111 are two parallel light beams.

In some embodiments, the sample 111 to be tested may include a plurality of observation planes thereon. The reflected light RL1 reflected by the sample 111 to be measured may include height information or topography information of these observation surfaces.

In the present embodiment, the reflected light RL1 reflected by the sample to be measured 111 passes through the half-mirror 122, and the transmitted reflected light RL1 and the detection light L emitted by the illumination unit 121 may include a plurality of same optical bands, that is, the half-mirror 122 does not have a band filtering function.

The beam splitter 131 is disposed on a side of the half mirror 122 opposite to the stage 110. The beam splitter 131 is used for splitting the reflected light RL1 into a plurality of split light I1, I2. In some embodiments, the reflectivity of the beam splitter 131 may comprise, for example, one-half, one-third, or one-fourth. This means that one half, one third or one fourth of the light entering the beam splitter 131 is reflected to other directions, and the rest of the light passes through the beam splitter 131.

More specifically, in the present embodiment, the reflectivity of the beam splitter 131 is, for example, one half, when the reflected light RL1 is incident on the beam splitter 131, one half of the reflected light RL1 is reflected by the reflecting surface 131R of the beam splitter 131, and the other half of the reflected light RL1 passes through the beam splitter 131, the reflected light RL1 can be evenly divided into two split light beams, each of the two split light beams has an intensity about half of the intensity of the reflected light RL1 and has a plurality of light bands identical to that of the reflected light RL 1.

In this embodiment, an included angle between the reflection surface 131R of the beam splitter 131 and the light path of the reflection light RL1 is, for example, 45 degrees, the reflection light RL1 can be divided into two split light beams I1 and I2, wherein the direction of one split light beam I1 is parallel to the X-axis direction and the direction of the other split light beam I2 is parallel to the Y-axis direction, and the two split light beams I1 and I2 have a plurality of optical bands same as that of the reflection light RL 1.

In some embodiments, the reflecting surface 131R of the beam splitter 131 can be adjusted in angle according to the light path of the reflected light RL1, for example, the included angle between the light path of the reflected light RL1 and the reflecting surface 131R can be greater than 45 degrees or less than 45 degrees.

The optical filters 141, 142 may be disposed along the optical paths of the split light rays I1, I2 at positions before the split light rays I1, I2 enter the image sensors 151, 152, and the optical filters 141, 142 are used to filter the split light rays I1, I2 into the filtered reflected light rays RL2, RL3. In the present embodiment, the filters 141 and 142 are used to filter out light beams of different wavelength bands, that is, the filtered and reflected light beams RL2 and RL3 are light beams of different wavelength bands. In this embodiment, the light split by the light filter is called as the filtered reflected light.

Specifically, in the present embodiment, the filter 141 and the image sensor 151 are respectively disposed on the optical path of the split light I1 parallel to the X-axis direction, and the filter 141 is used for filtering the split light I1 into the filtered reflected light RL2. In the present embodiment, the filter 141 is, for example, a red filter, and the band of the filtered and reflected light RL2 is, for example, 620nm to 750nm. The image sensor 151 receives the filtered reflected light RL2 to generate an imaging picture ImA.

In addition, the filter 142 and the image sensor 152 are respectively disposed on the light path of the split light I2 parallel to the Y-axis direction, and the filter 142 is used for filtering the split light I2 into a filtered reflected light RL3. In the present embodiment, the filter 142 is, for example, a blue light filter, and the wavelength band of the filtered and reflected light RL3 is, for example, 450nm to 495nm. The image sensor 152 receives the filtered reflected light RL3 to generate an imaged picture ImB.

The full width at half maximum value of the filtered reflected light RL2, RL3 may be less than or equal to 40nm, for example 30nm, 20nm or 10nm. When the full width at half maximum value is small enough, the contrast ratio which can be clearly shown by the specific defect can be more accurately reflected, and the noise of the wave band with poor contrast ratio is reduced, so that the image quality of the imaging pictures ImA and ImB is improved.

In the present embodiment, the difference between the central wavelengths of the wavelength band (e.g., 620nm to 750 nm) of the filtered reflected light RL2 and the wavelength band (e.g., 450nm to 495 nm) of the filtered reflected light RL3 is greater than 50nm. When the difference between the central wavelengths of the filtered and reflected light RL2, RL3 is larger, it means that the spectrum of the filtered and reflected light RL2, RL3 has a wider coverage, which can improve the chance that the specific feature is clearly displayed in the imaging frames ImA and/or ImB (i.e. has better contrast in one of the imaging frames). In addition, the full widths at half maximum (FWHM) of the filtered reflected rays RL2, RL3 may be different or the same.

In some embodiments, the Filters 141, 142 may include, for example, color Filters (Color Filters), band pass Filters (Optical band Filters), infrared Cut Filters (IR Cut Filters), infrared transmission Filters (IRpass Filters), or ultraviolet transmission Filters (UV Filters). The image sensor may include, for example, a Charge Coupled Device (CCD) or a Complementary Metal-Oxide-Semiconductor (CMOS), but the invention is not limited thereto.

It should be noted that the multiple observation surfaces of the sample 111 to be measured are, for example, different portions on the outer surface of the sample 111 to be measured, or if the structure of the surface of the sample 111 to be measured is transparent, one or more of the observation surfaces may also be the surface of the internal structure of the sample 111 to be measured.

To continue with fig. 1, fig. 2A is a schematic top view of a sample to be measured, and fig. 2B and fig. 2C are microscope images of positions a captured by the image sensors 151 and 152, respectively. More specifically, fig. 2B and 2C show the imaging frame a (ImA) and the imaging frame a (ImB) obtained from the position a of fig. 2A. Fig. 2D and 2E show the imaged picture B (ImA) and the imaged picture B (ImB) according to the position B in fig. 2A.

Comparing fig. 2B and fig. 2C, the imaged picture a (ImA) and the imaged picture a (ImB) show different contrast at the position a. Specifically, fig. 2B has a higher contrast at position a. In addition, comparing fig. 2D with fig. 2E, the imaged picture B (ImA) and the imaged picture B (ImB) show different contrasts at the position B. Specifically, FIG. 2E shows a higher contrast at position B, showing a more distinct topographical feature.

In other words, the imaged picture a (ImA) obtained by filtering the reflected light RL2 is suitable for judging whether the position a meets the standard; the imaging picture B (ImB) obtained by the filtering reflected light RL3 is suitable for judging whether the position B meets the standard or not, and further whether the target characteristics of the sample to be detected on the positions A and B corresponding to the position A and the position B meet the standard or not can be judged according to different wave bands (namely the filtering reflected light RL2 and the filtering reflected light RL 3) of the detection light. Compared with the prior art that light sources with different wavelengths are required to be replaced to individually detect the sample to be detected, the wafer defect inspection apparatus 100 of the embodiment can obtain a plurality of imaging frames ImA and ImB with different wavebands by one-time detection, thereby effectively saving time and improving detection efficiency.

Since the contrast ratio is a ratio of brightness of two pixels at the brightest and darkest positions in the imaged picture, the positions a and B referred to above are image areas (spots) in which the imaged pictures ImA and ImB include a plurality of pixels, and the contrast ratio of the imaged pictures ImA and ImB is calculated by taking two pixels out of the respective image areas and calculating the brightness ratio.

FIG. 3 is a schematic diagram of a wafer defect inspection apparatus according to another embodiment of the invention. Referring to fig. 3, the wafer inspection defect apparatus 100A of the present embodiment is similar to the wafer inspection defect apparatus 100 of fig. 1, and the difference between the two is that the wafer inspection defect apparatus 100A of the present embodiment further includes light-reducing members 161 and 162 capable of adjusting the light intensity.

The light reduction member 161 is disposed between the image sensor 151 and the filter 141, and the light reduction member 162 is disposed between the image sensor 152 and the filter 142. The light reducing members 161, 162 can reduce the light intensity of the filtered reflected light RL2, RL3 emitted from the light filtering members 141, 142, respectively, to control the amount of light entering the image sensors 151, 152, thereby generating the imaging pictures ImA, imB suitable for automatic detection.

In some embodiments, the light-reducing members 161, 162 may include a Neutral Density Filter (ND), a graded Neutral Density Filter (GND), or a Variable Neutral Density Filters (VND).

In some embodiments, the image sensors 151, 152 may have distinct focal lengths. For example, an image sensor corresponding to a longer wavelength band of the split light may have a longer focal length than an image sensor corresponding to a shorter wavelength band. Specifically, in the embodiment shown in fig. 4, the reflected light RL1 passes through the beam splitters 131, 132, and 133, respectively, and the image sensor 152 receives the filtered reflected light RL3 corresponding to the split light I6. Under this configuration, the split light I6 can be a wavelength band with a longer wavelength, and the image sensor 152 has a longer focal length than the other image sensors 151, 153, and 154. Thus, the split light I6 has a characteristic of a longer propagation distance and a lower attenuation degree in the beam splitters 131, 132, and 133, and is suitable for the arrangement of the image sensor 152 corresponding to a longer light path. In addition, since the heights of the observation surfaces of the sample 111 may be different, even though the optical path lengths of the image sensors 151 and 152 in fig. 3 may be the same, they can be focused on the observation surfaces respectively at different focal lengths to obtain a clear image.

Fig. 4 is a schematic diagram of a wafer defect inspection apparatus according to another embodiment of the invention. Referring to fig. 4, the wafer inspection defect apparatus 100B of the present embodiment is similar to the wafer inspection defect apparatus 100 of fig. 1, and the difference between the two is that the wafer inspection defect apparatus 100B of the present embodiment further includes beam splitters 132 and 133, filters 143 and 144, and image sensors 153 and 154.

The beam splitter 131, the beam splitter 132, and the beam splitter 133 are sequentially disposed on a side of the semi-transparent mirror 122 opposite to the stage 110. In the present embodiment, when the reflected light RL1 is emitted to the beam splitter 131, the reflected light is divided into two split light I1 and I2, wherein the split light I1 is a portion of the reflected light RL1 reflected by the reflecting surface 131R; and the split light I2 is the part of the reflected light RL1 passing through the beam splitter 131.

When the split light I2 parallel to the Y-axis direction is emitted to the beam splitter 132, the split light I2 is split into two split light I3 and I4, wherein the split light I3 is a portion of the split light I2 reflected by the reflecting surface 132R; and the split light I4 is the part of the split light that the split light I2 passes through the beam splitter 132. The direction of the split light I3 is parallel to the X-axis direction, and the direction of the split light I4 is parallel to the Y-axis direction, and the two split lights have the same optical band as the reflected light RL 1.

The filter 143 and the image sensor 153 are respectively disposed on the light path of the split light I3 parallel to the X-axis direction, and the filter 143 is configured to filter the split light I3 into a filtered reflected light RL4. In the present embodiment, the wavelength band of the filtered reflected light RL4 is, for example, 570nm to 590nm. The image sensor 153 receives the filtered reflected light RL4 to generate an imaged picture ImC.

When the split light I4 parallel to the Y-axis direction is emitted to the beam splitter 133, the split light I4 is split into two split light I5 and I6, wherein the split light I5 is a portion of the split light I4 reflected by the reflecting surface 133R; and the split light I6 is the part of the reflected light I4 passing through the beam splitter 133. The direction of the split light I5 is parallel to the X-axis direction, the direction of the split light I6 is parallel to the Y-axis direction, and the two split light I5 and I6 have the same optical wave band as the reflected light RL 1.

The filter 144 and the image sensor 154 are respectively disposed on the light path of the split light I5 parallel to the X-axis direction, and the filter 144 is configured to filter the split light I5 into a filtered reflected light RL5. In the present embodiment, the wavelength band of the filtered reflected light RL5 is, for example, 495nm to 570nm. The image sensor 154 receives the filtered reflected light RL5 to generate an imaged picture ImD.

In the embodiment, the wavelength bands of the filtered and reflected light beams RL2, RL3, RL4, RL5 are different, so that the imaging frames ImA, imB, imC, imD have different contrast expressions, and a user can select which position on the imaging frames ImA, imB, imC, imD is to be determined to be clearer according to the expressions with different contrast expressions.

It is noted that in some embodiments, beam splitter 131, beam splitter 132 and beam splitter 133 may have different reflectivities.

For example, the beam splitter 131, the beam splitter 132 and the beam splitter 133 can be sequentially arranged along the optical path of the reflected light through the half mirror 122, and the reflectivities of the beam splitter 131, the beam splitter 132 and the beam splitter 133 are incrementally arranged along the optical path of the reflected light RL1 through the half mirror 122.

For example, if the reflectivity of the half mirror 122 is one-half, the reflected light RL1 only remains 50% of the original light intensity when passing through the half mirror 122. At this time, assuming that the reflectivity of the beam splitter 131 is one fourth, the reflectivity of the beam splitter 132 is one third, and the reflectivity of the beam splitter 133 is one half, the reflected light RL1 with the light intensity of 50% is split into two split lights I1 and I2 with the light intensities of 12.5% and 37.5% by the beam splitter 131. The reflected light I2 with the light intensity of 37.5% is further split by the beam splitter 132 into two split light I3, I4 with the light intensity of 12.5% and 25%. The reflected light I4 with the light intensity of 25% is further split by the beam splitter 133 into two split light I5 and I6 with the light intensity of 12.5% respectively.

Such a design can make the light intensities of the split lights I1, I3, I5, I6 equal or close (12.5% in this case), and further make the light intensities of the filtered and reflected lights RL2, RL4, RL5, RL3 close. Therefore, the generated imaging pictures ImA, imB, imC and ImD have more consistent brightness and are convenient to interpret.

In summary, the wafer defect inspection apparatus of the present invention can separate the reflected light reflected by the sample to be inspected and filter out a plurality of split lights with different wave bands by the arrangement of the beam splitter and the light filter, and the split lights are received by the plurality of image sensors to synchronously generate a plurality of imaging pictures. Because the imaged frames have different contrasts at the corresponding positions, the imaged frame with higher contrast can be used for judging whether the position has defects or not. Compared with the known method that the light sources with different wavelengths are required to be replaced to individually detect the samples to be detected, the wafer defect inspection equipment can obtain a plurality of imaging pictures with different wave bands by one-time detection, so that the time can be effectively saved and the detection efficiency can be improved.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and these modifications or substitutions do not depart from the spirit of the corresponding technical solutions of the embodiments of the present invention. Features of the various embodiments may be combined and matched as desired, without departing from the spirit or ambit of the invention.

Claims (10)

1. A wafer defect inspection apparatus adapted to inspect a sample to be inspected, comprising:

the carrying platform is suitable for carrying the sample to be tested;

the light source module corresponds the microscope carrier setting, and includes:

an illumination unit for emitting detection light; and

the semi-transparent mirror is provided with a reflecting surface, the reflecting surface faces the illumination unit and the carrying platform, and the reflecting surface is suitable for reflecting the detection light to the sample to be detected so that the sample to be detected passes through the semi-transparent mirror through the reflected light reflecting the detection light;

the at least one spectroscope is arranged on one side of the semi-transparent mirror opposite to the carrier and used for receiving the reflected light rays passing through the semi-transparent mirror and separating a plurality of light splitting light rays;

a plurality of optical filters respectively disposed on optical paths of the plurality of light splitting rays, and the plurality of optical filters are configured to allow the plurality of light splitting rays to pass through a plurality of different wavelength bands; and

the image sensors are arranged on the light paths of the plurality of light splitting rays and are respectively positioned on one side of one of the light filtering pieces opposite to the light splitting mirror, each image sensor receives one of the light splitting rays to generate an imaging picture, and images corresponding to the same position in any two imaging pictures have different contrasts.

2. The wafer defect detecting apparatus as claimed in claim 1, wherein the detecting light incident to the half mirror and the reflected light passing through the half mirror have the same wavelength band.

3. The wafer defect inspection apparatus of claim 1, wherein a full width at half maximum of each of the wavelength bands is less than 40 nm.

4. The wafer defect inspection apparatus of claim 1, wherein the plurality of wavelength bands have different full widths at half maximum.

5. The wafer defect inspection apparatus of claim 1, wherein a difference between two central wavelengths of any two of the plurality of wavelength bands is greater than 50nm.

6. The wafer defect detecting apparatus of claim 1, wherein the plurality of image sensors have different focal lengths.

7. The wafer defect inspection apparatus as claimed in claim 1, wherein one of the image sensors corresponding to the longer wavelength band of the split light has a longer focal length than the other of the image sensors corresponding to the shorter wavelength band of the split light.

8. The wafer defect detecting apparatus as claimed in claim 1, wherein the detecting light and the reflected light incident on the sample to be detected by the half-lens are parallel light.

9. The wafer defect detecting apparatus as claimed in claim 1, wherein the at least one beam splitter includes a plurality of beam splitters arranged in sequence along a light path of the reflected light through the semi-transparent mirror, and reflectances of the plurality of beam splitters increase along the light path of the reflected light through the semi-transparent mirror.

10. The wafer defect detecting apparatus as claimed in claim 1, further comprising at least one light-reducing member disposed between at least one of the plurality of image sensors and the corresponding light-filtering member.

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