Wafer defect detection apparatus

Abstract

The present application provides a wafer defect detection device suitable for detecting a sample under test including two detection features. The wafer defect detection device includes a stage, a light source module and an image sensor. The stage is suitable for carrying the sample under test. The light source module is used to output detection light to the sample under test on the stage and reflect the reflected light. The detection light includes a spectrum of a first light and a second light. The first light and the second light have different two peak wavelengths. The spectrum of the first light is suitable for detecting one of the detection features. The spectrum of the second light is suitable for detecting the other detection feature. The light intensity of the first light and the light intensity of the second light are independently controlled. The reflected light contains an image frame. The image frame displays the two detection features. The image sensor is disposed on the path of the reflected light and is suitable for receiving the image frame. The wafer defect detection device of the present application can obtain the image frame of the detection features with high contrast through one detection, so as to have high detection efficiency.

Description

Technical Field

[0001] This invention relates to a wafer defect detection device, and more particularly to a wafer defect detection device with high detection efficiency. Background Technology

[0002] Currently, using Automated Optical Inspection (AOI) to determine whether a sample is good or bad is quite common. Generally, a sample will have multiple inspection features that need to be verified to meet standards. If the same wavelength of light is used for all inspection features at different locations or with different shapes, the image contrast of some features may be insufficient to identify defects. Because the contrast of these inspection features does not meet inspection requirements, the common practice is to perform inspections using different wavelengths of light, and then use post-processing techniques to synthesize an image suitable for automated optical inspection, or to directly interpret the results from these different wavelengths of light.

[0003] However, both post-image processing and separate interpretation consume additional manpower and time. In particular, for increasingly miniaturized semiconductor packaging structures, the number of features to be inspected on a single wafer typically reaches millions. Therefore, using the methods described above to overcome image contrast issues inevitably significantly reduces the efficiency of automated optical inspection. Thus, how to clearly determine whether multiple features meet standards in a single inspection is a research direction in this field. Summary of the Invention

[0004] This invention provides a wafer defect detection device that can obtain an image with high contrast detection features in a single inspection, thus achieving high detection efficiency.

[0005] This invention discloses a wafer defect detection device suitable for detecting a sample to be tested, the sample including two detection features. The wafer defect detection device includes a stage, a light source module, and an image sensor. The stage is suitable for holding the sample to be tested. The light source module outputs detection light to the sample to be tested on the stage and reflects the reflected light. The detection light includes the spectrum of a first light and the spectrum of a second light, the first light and the second light having two different peak wavelengths. The spectrum of the first light is suitable for detecting one of the detection features, and the spectrum of the second light is suitable for detecting the other detection feature. The luminous intensity of the first light and the luminous intensity of the second light are independently controlled. The reflected light contains an image, and the image displays the two detection features. The image sensor is disposed in the path of the reflected light and is suitable for receiving the image.

[0006] Based on the above, the detection light output by the light source module of the wafer defect inspection device of the present invention includes a first light and a second light with two different peak wavelengths. The spectrum of the first light is suitable for detecting one detection feature, and the spectrum of the second light is suitable for detecting the other detection feature. After the detection light shines on the sample under test, it reflects a reflected light, and the image of the reflected light displays the two detection features. Since the reflected light also includes the spectrum of the first light and the spectrum of the second light, the wafer defect inspection device of the present invention utilizes the characteristic that the spectrum of the first light is suitable for detecting one detection feature, and the spectrum of the second light is suitable for detecting the other detection feature. The image of the reflected light also has good contrast between the two detection features, resulting in a clear representation. Furthermore, the light intensity of the first light and the light intensity of the second light in the light source module are independently controlled, and the light intensity of the first light and the second light can be adjusted as needed to optimize the contrast between the first detection feature and the second detection feature. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of a wafer defect detection device according to an embodiment of the present invention;

[0008] Figure 2 yes Figure 1 A schematic diagram of the light source module;

[0009] Figure 3A This is a schematic diagram of the sample to be tested;

[0010] Figure 3B It is a microscope image of the first detection feature of the sample under test, detected by the first light beam.

[0011] Figure 3C It is a microscope image of the second detection feature of the sample under test detected by the first light beam;

[0012] Figure 3D This is a microscope image of the first detection feature of the sample under test, detected by the second light beam.

[0013] Figure 3E This is a microscope image of the second detection feature of the sample being tested, detected by the second light beam.

[0014] Figure 3F It is a microscope image of the first detection feature of the sample to be tested, which is detected by reflecting light.

[0015] Figure 3G This is a microscope image of the second detection feature of the sample being tested, obtained by detecting reflected light.

[0016] Figure 4 This is a schematic diagram of a light source module according to another embodiment of the present invention;

[0017] Figure 5 This is a schematic diagram of a switching mechanism and a filter according to an embodiment of the present invention.

[0018] Explanation of reference numerals in the attached figures

[0019] L1: First ray;

[0020] L2: Second ray;

[0021] LD: Detects light;

[0022] LR: Reflected light;

[0023] IM: Image / View;

[0024] A: First detection feature;

[0025] B: Second detection feature;

[0026] 10: The sample to be tested;

[0027] 100: Wafer defect inspection equipment;

[0028] 110: Platform;

[0029] 120, 120a: Light source module;

[0030] 1201, 1202: Coupler lenses;

[0031] 121: First light source;

[0032] 122: Second light source;

[0033] 123: Optical transmission components;

[0034] 124: First entrance;

[0035] 125: Second entrance;

[0036] 126: Export;

[0037] 127: Continuous spectrum light source;

[0038] 128, 128a, 128b, 128c: Filters;

[0039] 129: Light emission control mechanism;

[0040] 130: Image sensor;

[0041] 140: Semi-transparent mirror;

[0042] 142: Reflective surface;

[0043] 150: Switching mechanism. Detailed Implementation

[0044] 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 component reference numerals are used in the drawings and description to denote the same or similar parts.

[0045] Figure 1 This is a schematic diagram of a wafer defect detection device according to an embodiment of the present invention. Please refer to... Figure 1 The wafer defect detection device 100 of this embodiment is suitable for detecting the sample 10 to be tested. The sample 10 to be tested is, for example, part of a wafer, but is not limited thereto.

[0046] The wafer defect inspection equipment 100 includes a stage 110, a light source module 120, and an image sensor 130. The stage 110 is suitable for holding the sample 10 to be tested. The light source module 120 is used to output detection light LD.

[0047] In some embodiments, the spectrum of the detection light LD may include two of the following: ultraviolet light (wavelength range of about 100 nm to 380 nm), violet light (wavelength range of about 380 nm to 450 nm), blue light (wavelength range of about 450 nm to 495 nm), green light (wavelength range of about 495 nm to 570 nm), yellow light (wavelength range of about 570 nm to 590 nm), orange light (wavelength range of about 590 nm to 620 nm), red light (wavelength range of about 620 nm to 750 nm), and infrared light (wavelength range of about 750 nm to 1 mm).

[0048] In this embodiment, the detection light LD includes the spectrum of a first light L1 and the spectrum of a second light L2. The spectrum of the first light L1 is, for example, the spectrum of red light (wavelength range of approximately 620 nm to 750 nm), and the spectrum of the second light L2 is, for example, the spectrum of green light (wavelength range of approximately 495 nm to 570 nm), but the spectra of the first light L1 and the second light L2 are not limited thereto. The spectrum of the first light L1 can be selected to be suitable for detecting the first detection feature A of the sample 10 to be tested. Figure 3A The spectrum of the second light L2 can be selected to be suitable for detecting the second detection feature B of the sample 10 to be tested. Figure 3A The spectrum of ).

[0049] The first ray L1 and the second ray L2 have two distinct peak wavelengths. The difference between the two peak wavelengths is greater than or equal to 50 nanometers, and the full width at half maximum (FWHM) of either peak wavelength is less than 40 nanometers. Here, when the first detection feature A and the second detection feature B are detected using rays with the same peak wavelength, if the contrast of the image displayed by one of them is significantly lower, it indicates that the spectrum of that ray is not suitable for that detection feature. In other words, when the peak wavelength difference between the first ray L1 and the second ray L2 is large, the wider spectrum coverage of the detection ray LD increases the chance of obtaining high-contrast images for different detection features. Furthermore, having a sufficiently narrow FWHM for the first ray L1 and the second ray L2 is a preferred configuration, as it reduces noise in the bands with poor contrast for the first detection feature A and the second detection feature B, thereby improving image quality. The FWHM of the first ray L1 and the second ray L2 can be different or the same.

[0050] Figure 2 yes Figure 1 A schematic diagram of the light source module. Please refer to [link / reference]. Figure 2 In this embodiment, the light source module 120 includes a first light source 121 that emits a first light ray L1, a second light source 122 that emits a second light ray L2, and a light transmission element 123.

[0051] The optical transmission element 123 may be, for example, a combiner fiber or a light guide tube, but is not limited thereto. The optical transmission element 123 includes a first inlet 124, a second inlet 125, and an outlet 126. A first light source 121 is coupled to the first inlet 124, and a second light source 122 is coupled to the second inlet 125.

[0052] Specifically, a coupling prism 1201 is provided between the first light source 121 and the first entrance 124 of the light transmission device 123, so that the first light ray L1 emitted by the first light source 121 enters the first entrance 124. A coupling prism 1202 is provided between the second light source 122 and the second entrance 125 of the light transmission device 123, so that the second light ray L2 emitted by the second light source 122 enters the second entrance 125.

[0053] The first light ray L1 and the second light ray L2 are mixed in the optical transmission device 123 to form the detection light LD. The output 126 of the optical transmission device 123 outputs the detection light LD, which is a mixture of the first light ray L1 and the second light ray L2. In other words, the detection light LD is a mixed light of the first light ray L1 and the second light ray L2.

[0054] Furthermore, since the first light source 121 and the second light source 122 of the light source module 120 are two independent light sources, their luminous intensity can be controlled and adjusted independently. Therefore, the luminous intensity of the first light and the luminous intensity of the second light of the light source module can be controlled independently.

[0055] In addition, the light source module 120 also includes a light emission control mechanism 129, located next to the exit 126 of the light transmission element 123, to control the light emission time of the detection light LD. The light emission control mechanism 129 is, for example, a shutter, which can control the opening or closing, and the time and frequency of the switching, so that the detection light LD can have various effects such as flashing and blackout.

[0056] Reference Figure 1 The wafer defect inspection equipment 100 also includes a semi-transparent mirror 140. The semi-transparent mirror 140 includes a reflective surface 142 facing the stage 110 and the light source module 120. The reflective surface 142 reflects the detection light LD onto the sample 10 under test on the stage 110, thereby changing the direction of the detection light LD. The detection light LD is reflected by the sample 10 under test to form a reflected light LR. In some embodiments, the sample 10 under test may include multiple observation surfaces. The reflected light LR reflected from the sample 10 under test may include height information or topographic information (e.g., impurities, film thickness inhomogeneity, cracks, defects) of these observation surfaces.

[0057] A semi-transparent mirror 140 is located between the stage 110 and the image sensor 130, and the image sensor 130 is positioned in the path of the reflected light LR. Therefore, the reflected light LR passes through the semi-transparent mirror 140 and reaches the image sensor 130. In this embodiment, the image sensor 130 may include, for example, a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS), but the invention is not limited thereto. The field of view of the image sensor 130 covers the illumination range of the light source module 120.

[0058] In this embodiment, the detection ray LD reflected by the reflective surface 142 and the reflected ray LR reflected by the sample 10 are two parallel rays, and the detection ray LD and the reflected ray LR are coaxial. Furthermore, in this embodiment, the reflected ray LR passing through the semi-transparent lens 140 and the detection ray LD emitted by the light source module 120 may include the same multiple optical wavelengths. That is, the semi-transparent lens 140 does not have a wavelength filtering function. In other words, the reflected ray LR also includes the optical wavelengths of the first ray L1 and the second ray L2.

[0059] Figure 3A This is a schematic diagram of the sample to be tested. Please refer to [link / reference]. Figure 3AThe sample to be tested 10 includes a first detection feature A and a second detection feature B. The first detection feature A is, for example, located near a corner of the sample to be tested 10, or for example, located near the center of the sample to be tested 10.

[0060] Figure 3B It uses the first light beam to detect the first detection feature of the sample under test using microscopic imaging. Figure 3C It uses a first light beam to detect the second detection feature of the sample under test using microscopic imaging. Please refer to [link to relevant documentation]. Figure 3B and Figure 3C Each of the first detection feature A and the second detection feature B has a first native contrast under the first light L1 detection.

[0061] Figure 3D It uses a second light beam to detect the first detection feature of the sample under test using microscopic imaging. Figure 3E This involves using a second light beam to detect a second detection feature on the sample under test using microscopic imaging. Please refer to [link to relevant documentation]. Figure 3D and Figure 3E Each of the first detection feature A and the second detection feature B has a second native contrast under the second light L2 detection.

[0062] Compare Figure 3B and Figure 3D It can be clearly seen that Figure 3B The displayed first native contrast of the first detected feature A is greater than Figure 3D The displayed second native contrast for the first detected feature A, i.e. Figure 3B The displayed detection feature A has a clearer shape. Therefore, the first ray L1 is more suitable for detecting the first detection feature A.

[0063] Compare again Figure 3C and Figure 3E , Figure 3E The displayed second native contrast for the second detection feature B is greater than Figure 3C The displayed first native contrast for the second detection feature B, i.e. Figure 3E The displayed detection feature B has a clearer morphology. Therefore, the second ray L2 is more suitable for detecting the second detection feature B.

[0064] Figure 3F It is a microscope imaging method that uses reflected light to detect the first detection feature of the sample. Figure 3G This is a microscopic imaging technique that uses reflected light to detect the second detection feature of the sample. Please refer to [link / reference]. Figure 3F and Figure 3G In one embodiment, the reflected light LR ( Figure 1 In the generated image IM, each of the first detection feature A and the second detection feature B has output contrast under reflected light LR detection. Furthermore, Figure 3F The output contrast can be between Figure 3B First native contrast ratio and Figure 3D Between the second native contrast ratio. Furthermore... Figure 3G The output contrast can be between Figure 3C First native contrast ratio and Figure 3E Between the second native contrast ratio.

[0065] In summary, the detection ray LD contains the spectra of a first ray L1 suitable for detecting the first detection feature A and a second ray L2 suitable for detecting the second detection feature B, while the spectrum of the reflected ray LR received by the image sensor 130 is a mixture of the first ray L1 and the second ray L2. Here, the contrast of the reflected ray LR in detecting the first detection feature A and the second detection feature B (i.e., Figure 3F and Figure 3G () respectively lower than Figure 3B and Figure 3E But respectively higher than Figure 3D and Figure 3C The contrast is improved. Compared to existing detection methods that require changing light sources of different wavelengths to detect the sample separately and obtain multiple images formed by light of different wavelengths (e.g., first light and second light), the wafer defect inspection equipment 100 of this embodiment mixes the light for detection according to the detection spectrum applicable to each detection feature. Thus, the wafer defect inspection equipment 100 of this embodiment can obtain sufficiently clear images of the first detection feature A and the second detection feature B in a single detection, thereby effectively improving detection efficiency. Of course, the detection features of the sample 10 and the number and spectrum of light wavelengths output by the light source module 120 are not limited to this.

[0066] also, Figure 1 The wafer defect inspection equipment 100 can also use other light source modules. Figure 4 This is a schematic diagram of a light source module according to another embodiment of the present invention. Please refer to... Figure 4 The light source module 120a includes a continuous spectrum light source 127 and at least one filter 128. The multi-band light emitted by the continuous spectrum light source 127 passes through the filter 128 to output detection light LD.

[0067] The main difference between the light source module 120a of this embodiment and the light source module 120 of the previous embodiment is that the light source module 120 of the previous embodiment directly merges two or more wavelength-tuned light sources to become the detection light, while the light source module 120a of this embodiment retains two or more light sources with different peak wavelengths by filtering the source of the detection light (continuous spectrum light source).

[0068] In some embodiments, the continuous spectrum light source 127 may include, for example, a xenon lamp, mercury lamp, or tungsten filament lamp with multiple light bands. In some embodiments, the continuous spectrum light source 127 may include a light-emitting diode (LED) chip and a wavelength conversion material, with the 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 present invention is not limited thereto.

[0069] In this embodiment, the filter 128 has two or more transmission spectra. The transmission spectrum of the filter 128 corresponds to the two peak wavelengths of the first light ray L1 and the second light ray L2. The filter 128 may include, for example, color filters, optical bandpass filters, infrared cut-off filters, infrared pass-through filters, and / or ultraviolet pass-through filters. The filter 128 can filter out the first light ray L1 and the second light ray L2, and filter out other unwanted spectral segments.

[0070] In this embodiment, the filter 128 is, for example, a filter that combines multiple materials. These materials have different transmittance ratios for different wavelengths of light. By adjusting the proportions of these materials (or changing the materials used in combination), the transmittance ratios for light corresponding to each wavelength can be determined. For example, if it is desired that the intensity of red light after passing through the filter 128 is higher than that of green light, a material with a higher transmittance for red light and a lower transmittance for green light can be selected, or the content of this material in the filter 128 can be increased.

[0071] To facilitate adjustment of the light intensity of the first ray L1 and the second ray L2, multiple filters with different material ratios can be pre-mixed and switched as needed. For example, Figure 5 This is a schematic diagram of a switching mechanism and a filter according to an embodiment of the present invention. Please refer to [link / reference]. Figure 5 In this embodiment, the switching mechanism 150 can be disposed at the continuous spectrum light source 127 ( Figure 4 ) and the test sample 10 ( Figure 1 Between the light sources, the switching mechanism 150 can be, for example, a rotating wheel device corresponding to the light outlet of the continuous spectrum light source 127, but is not limited thereto. Multiple filters 128a, 128b, and 128c are switchably disposed in the switching mechanism, and rotated to allow one of the filters 128a, 128b, and 128c to correspond to the continuous spectrum light source 127. Figure 4 The light outlet is used to achieve independent control of the first light ray L1 and the second light ray L2.

[0072] Please return Figure 4 In this embodiment, the light emission control mechanism 129 can be selectively located next to the filter 128 to control the emission time of the detection light LD. The light emission control mechanism 129 is located, for example, between the continuous spectrum light source 127 and the filter 128; however, in other embodiments, the filter 128 may also be located between the continuous spectrum light source 127 and the light emission control mechanism 129. The light emission control mechanism 129 is, for example, a shutter, which can control the opening or closing, and the timing and frequency of the switching, so that the detection light LD can have various effects such as flashing or blackout.

[0073] In summary, the detection light output by the light source module of the wafer defect detection device of the present invention includes a first light and a second light with two different peak wavelengths. Since the spectrum of the reflected light is a mixture of the first and second light, the wafer defect detection device of the present invention can simultaneously obtain images of the first and second detection features with better contrast using the reflected light, thereby clearly presenting the defect morphology of these detection features. Furthermore, the light intensity of the first and second light of the light source module is independently controlled, and the light intensity of the first and second light can be adjusted as needed to optimize the contrast of the first and second detection features.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wafer defect detection device, suitable for detecting a sample to be tested, wherein the sample to be tested includes two detection features, characterized in that, The wafer defect detection equipment includes: A stage, suitable for holding the sample to be tested; A light source module outputs detection light to the sample under test on the stage. After the detection light illuminates the sample, it reflects reflected light. The detection light includes the spectrum of a first light and the spectrum of a second light. The first light and the second light have two different peak wavelengths. The spectrum of the first light is suitable for detecting one of the two detection features, and the spectrum of the second light is suitable for detecting the other of the two detection features. The light intensity of the first light and the light intensity of the second light are independently controlled. The reflected light contains an image, and the image displays the two detection features. An image sensor is positioned along the path of the reflected light and is adapted to receive the image. In the image, each of the two detection features has an output contrast under the reflected light detection, each of the two detection features has a first native contrast under the first light detection, each of the two detection features has a second native contrast under the second light detection, and each of the output contrasts is respectively between the first native contrast and the second native contrast of the detection feature.

2. The wafer defect detection equipment according to claim 1, characterized in that, It also includes a semi-transparent lens located between the stage and the image sensor. The semi-transparent lens includes a reflective surface facing the stage and the light source module. The reflective surface reflects the detection light to the sample to be tested on the stage, and the reflected light passes through the semi-transparent lens and is incident on the image sensor.

3. The wafer defect detection equipment according to claim 1, characterized in that, The difference between the two peak wavelengths is greater than or equal to 50 nanometers.

4. The wafer defect detection equipment according to claim 1, characterized in that, The full width at half maximum (FWHM) of either of the two peak wavelengths is less than 40 nanometers.

5. The wafer defect detection equipment according to claim 1, characterized in that, The light source module includes a first light source that emits the first light, a second light source that emits the second light, and a light transmission device, wherein the light transmission device is coupled to the first light source and the second light source.

6. The wafer defect detection equipment according to claim 5, characterized in that, The light source module also includes a light emission control mechanism located next to the light transmission component to control the emission time of the detection light.

7. The wafer defect detection equipment according to claim 1, characterized in that, The light source module includes a continuous spectrum light source and at least one filter. The multi-band light emitted by the continuous spectrum light source passes through the at least one filter to output the detection light, and the transmission spectrum of the at least one filter corresponds to the two peak wavelengths of the first light and the second light.

8. The wafer defect detection equipment according to claim 7, characterized in that, The at least one filter is a plurality of filters, and at least one of the first light rays and the second light rays has a different transmittance ratio relative to any two of the plurality of filters.

9. The wafer defect detection equipment according to claim 8, characterized in that, It also includes a switching mechanism disposed between the continuous spectrum light source and the sample to be tested, and the plurality of filters are switchably disposed in the switching mechanism.

Images