Reflective fourier ptychographic microscope apparatus

Abstract

The present invention relates to a reflective Fourier ptychographic microscope apparatus, and more specifically to a reflective Fourier ptychographic microscope apparatus comprising: a first illuminator disposed on a first panel and provided with a plurality of first LED light sources sequentially radiated at mutually different angles onto an object being measured; a second illuminator disposed on a second panel and provided with a plurality of second LED light sources sequentially radiated at mutually different angles onto the object being measured after the radiation by the first illuminator; an objective lens having imaged thereonto imaging beams formed by the reflection of the LED beams, emitted from the first illuminator and the second illuminator, radiated onto the object being measured; and a prism positioned between the objective lens and the object being measured so as to reflect the LED beams emitted from the second illuminator so that same are radiated onto the object being measured.

Description

Reflection Fourier tychographic microscope device

[0001] The present invention relates to a reflection type Fourier tychographic microscope device, and more particularly, to a reflection type Fourier tychographic microscope device comprising: a first illuminator having a plurality of first LED light sources arranged on a first panel and sequentially irradiating a measurement object at different angles; a second illuminator having a plurality of second LED light sources arranged on a second panel and sequentially irradiating the measurement object at different angles after irradiation by the first illuminator; an objective lens irradiating the measurement object with LED beams emitted from the first illuminator and the second illuminator and forming an image of reflected imaging beams; and a prism positioned between the objective lens and the measurement object and reflecting the LED beam emitted from the second illuminator and irradiating the measurement object with the LED beam.

[0002] This invention is the result of a research project on international joint technology development supported by the Ministry of Trade, Industry and Energy and the Korea Institute for Advancement of Technology. The research project name is Development of Microdisplay Measurement System. The project performing organization is Small Machines Co., Ltd., with a contribution ratio of 1 / 1. The project identification number is 1415177565, the project number is P0019802, and the research period is 2021.12.01 ~ 2024.11.30.

[0003] Recently, due to the rapid development of smart devices such as smartphones, artificial intelligence (AI), 5th generation (5G) mobile communications, and Internet of Things (IoT) technologies, the demand for semiconductors used in these devices is rapidly increasing.

[0004] As the circuit line widths of these semiconductors become increasingly smaller, the packaging that protects the semiconductors is also becoming smaller.

[0005] Accordingly, as the semiconductor line miniaturization process and semiconductor packaging miniaturization progress, the technology for meticulously inspecting defects such as scratches on the semiconductor surface that occur during the semiconductor manufacturing process is also becoming more precise.

[0006] To this end, high-resolution equipment is required to measure circuit lines of semiconductors or the surfaces of miniaturized semiconductor packaging, which are miniaturized to the level of several micrometers (μm).

[0007] The above resolution is an indicator of the limit performance of a signal measurement method or measuring equipment, and the higher the resolution, the more precise and accurate the measurement.

[0008] And, when taking a surface image of a component such as a semiconductor, only light intensity information can be obtained, but from a wave optics perspective, in order to completely express light, both the light intensity and phase must be obtained simultaneously, and a holographic microscopy technology that can measure the three-dimensional structure of a surface by obtaining such light intensity and phase information simultaneously is known.

[0009] However, conventional holographic microscopes had the limitation that they had to take multiple pictures of the same sample to obtain a high-resolution 3D holographic image.

[0010] Therefore, a Fourier ptychographic microscopy apparatus (abbreviated as FPM) technology was developed that can measure samples more precisely and quickly than the above holographic microscope.

[0011] The above Fourier tachographic microscope device is a device that can measure an object at high resolution by illuminating the object from various angles using an LED and an objective lens and merging the reflected signals to increase the resolution. Since the phase can be calculated without using the reference beam used in the above-described holographic microscope, the device can be miniaturized, and since the signal beam and the reference beam are not distinguished, it has the advantage of being resistant to vibration.

[0012] In addition, the holographic microscope described above has a small FOV (field of view, size of the actual object seen by the camera) and DOF (depth of focus, distance between the lens and the object) when using an objective lens with a high NA (numerical aperture, resolution of the lens) to obtain high resolution, whereas the Fourier tachographic microscope device has the advantage of having a wide FOV and DOF because it can obtain high resolution even with an objective lens with a low NA (numerical aperture) by replacing the condenser lens with an LED array to enable a high illumination angle, and also has the advantage of not requiring a mechanical drive unit because a high illumination angle can be obtained with the LED array.

[0013] These Fourier tachographic microscopes (FPM) have recently been developed into a technology that can measure the surface of a target sample with a precise resolution of several hundred nanometers (nm).

[0014] FIG. 1 is a drawing showing a conventional FPM device, and the conventional FPM device (10) is configured to include a first illuminator (20) corresponding to a bright field illuminator and having a plurality of LEDs that illuminate a measurement object (1) at different angles, an objective lens (30) that forms an image of an imaging beam that is illuminated and reflected by the measurement object (1), a second illuminator (40) corresponding to a dark field illuminator, a condenser lens (50), a photodetector (60) that obtains an image of the measurement object (1) from the imaging beam of the measurement object (1), a beam splitter (70), and an optical system (80).

[0015] The above first illuminator (20) is composed of a first panel (21) and a plurality of first LED light sources (22) arranged on the first panel (21), and the above second illuminator (40) is composed of a second panel (41) and a plurality of second LED light sources (42) arranged on the second panel (41).

[0016] At this time, the first panel (21) is in the shape of a flat plate and a plurality of first LED light sources (22) are arranged in a ring shape radially from the center point of the first panel (21), and the second panel (41) is in the shape of a flat plate and a plurality of second LED light sources (42) are arranged in a ring shape radially from the center point of the second panel (41).

[0017] And, the FPM device (10) controls the first LED light sources (22) on the first LED panel (21) to emit light sequentially, starting from the first LED light source (22) located at the center point of the first panel (21) of the first illuminator (20).

[0018] Then, the LED beam emitted by the first LED light sources (22) of the first illuminator (20) passes through an optical system (80) composed of a first lens (81) and a second lens (82), is reflected by a beam splitter (70), passes through an objective lens (30), and is irradiated onto a measurement object (1). After the irradiation, the imaging beam reflected from the measurement object (1) is focused on the back focal plane of the objective lens (30), and the focused imaged beam passes through the beam splitter (70) again and is focused on a condenser lens (50). The focused imaging beam is received by a photodetector (60).

[0019] Then, the photodetector (60) acquires an image for each of the received imaging beams, performs a fast Fourier transform on each acquired image, and stitches the images to position them at the corresponding positions of θx and θy in the spectral domain to derive the phase.

[0020] Next, the FPM device (10) drives the second illuminator (40). The second illuminator (40) is a dark field illuminator that directly projects light onto the measurement target (1) without passing through the objective lens (30).

[0021] Then, starting from the second LED light source (42) located at the center point of the second panel (41) of the second lighting device (40), the second LED light sources (42) on the second LED panel (41) sequentially emit light.

[0022] And, the LED beams emitted by the second LED light sources (42) of the second illuminator (40) are directly irradiated to the measurement target (1) at different angles.

[0023] Then, the LED beam irradiated to the measurement object (1) is reflected after being irradiated to the measurement object (1) and is imaged on the back focal plane of the objective lens (30), and the imaged beam passes through the beam splitter (70) again and is focused on the condenser lens (50), and the focused imaging beam is received by the photodetector (60).

[0024] And, the photodetector (60) acquires an image for each of the received imaging beams, and calculates the phase of the image by stitching the images of each acquired imaging beam through fast Fourier transform.

[0025] Thereafter, the FPM device (10) acquires a spectrum by performing an inverse Fourier transform on the image acquired by receiving light from the first illuminator (20) and the second illuminator (40), converges the phase through an overlapping area to acquire phase information of the image, and generates a composite image having phase information by utilizing the images acquired by the first illuminator (20) and the second illuminator (40), thereby enabling measurement of the surface of the measurement target (1).

[0026] However, the conventional FPM device (10) as described above had a problem in that it was difficult to secure a sufficient distance between the second illuminator (40) and the measurement target (1) to satisfy the coherent illumination condition.

[0027] In addition, conventional FPM devices have the disadvantage of taking a lot of time to measure a large-area measurement target because they divide the surface measurement area into pieces and measure it when the surface of the measurement target sample is large.

[0028] Therefore, in order to improve production efficiency in actual semiconductor processes, it is necessary to shorten the inspection time of semiconductors, and therefore, there is a need to develop a technology that can easily measure large-area measurement targets.

[0029] Meanwhile, as a prior art related to an FPM device, the technology of an FPM device is known in Korean Patent Publication No. 10-2021-0105711.

[0030] The present invention was created to solve the above-mentioned problems of the prior art, and the technical task of the present invention is to provide an FPM device that can secure a sufficient distance between a second illuminator and a measurement target so as to satisfy a coherent illumination condition, and can easily measure the surface of a measurement target having a large area.

[0031] In order to achieve the above technical task, the reflective FPM device of the present invention is characterized by comprising: a first illuminator having a plurality of first LED light sources arranged on a first panel and sequentially irradiating a measurement object at different angles; a second illuminator having a plurality of second LED light sources arranged on a second panel and sequentially irradiating the measurement object at different angles after irradiation by the first illuminator; an objective lens irradiating the measurement object with LED beams emitted from the first illuminator and the second illuminator and forming an image of the reflected imaging beams; and a prism positioned between the objective lens and the measurement object and reflecting the LED beam emitted from the second illuminator and irradiating the measurement object with the reflected LED beam.

[0032] The reflective FPM device of the present invention having the above configuration has a second illuminator positioned above the measurement target, so that a large space for irradiating the measurement target can be secured, and thus a measurement target with a large area can be easily measured at once, thereby shortening the inspection time of semiconductors and thereby improving production efficiency in semiconductor processes.

[0033] In addition, since a sufficient distance is secured between the second illuminator and the measurement target, the distance between the second illuminator and the measurement target can be secured at a distance sufficient to satisfy the coherent illumination condition, thereby obtaining the effect of performing semiconductor inspection more accurately.

[0034] Figure 1 is a configuration diagram of a conventional FPM device.

[0035] Figure 2 is a configuration diagram of the FPM device of the present invention;

[0036] Figure 3 is a detailed view of the prism of the FPM device of the present invention;

[0037] FIG. 4 is a drawing showing the reflection state of a beam irradiated onto a measurement target by a prism of the FPM device of the present invention.

[0038] Hereinafter, the configuration of the reflective FPM device of the present invention will be described in detail with reference to the drawings.

[0039] However, the disclosed drawings are provided as examples to ensure that those skilled in the art can sufficiently convey the spirit of the present invention. Therefore, the present invention is not limited to the drawings presented below and may be embodied in other aspects.

[0040] In addition, unless otherwise defined, terms used in the specification of the present invention have meanings commonly understood by a person of ordinary skill in the art to which the present invention pertains, and detailed descriptions of known functions and configurations that may unnecessarily obscure the gist of the present invention in the following description and accompanying drawings are omitted.

[0041]

[0042] Figure 2 is a configuration diagram of the FPM device of the present invention.

[0043] Referring to the drawing, the FPM device (100) of the present invention includes a first illuminator (120) having a plurality of first LED light sources (122) arranged on a first panel (121) and sequentially irradiating the measurement object (1) at different angles, and a second illuminator (140) having a plurality of second LED light sources (142) arranged on a second panel (141) and sequentially irradiating the measurement object (1) at different angles after irradiation by the first illuminator (120).

[0044] The above first illuminator (120) is used as a bright field illuminator of the FPM device (100) of the present invention, and the above second illuminator (140) is used as a dark field illuminator of the FPM device (100) of the present invention.

[0045] In addition, it is configured to include an objective lens (130) in which LED beams emitted from the first illuminator (120) and the second illuminator (140) irradiate the measurement object (1) and the reflected imaging beams are imaged, a beam splitter (170) that reflects the LED beam emitted from the first illuminator (120) toward the measurement object (1), a condenser lens (150) that condenses the imaging beam formed on the objective lens (130), and a photodetector (160) that obtains an image of the measurement object (1) from the imaging beams condensed on the condenser lens (150).

[0046] The first panel (121) has a circular flat plate shape and a plurality of first LED light sources (122) are arranged in a ring shape radially from the center point of the first panel (121), and the second panel (141) has a circular flat plate shape and a plurality of second LED light sources (142) are arranged in a ring shape radially from the center point of the second panel (141).

[0047] In addition, it includes an optical system (180) installed between the first illuminator (120) and the beam splitter (140) to pass the LED beam emitted from the first illuminator (120) through the beam splitter (170).

[0048] The above optical system is composed of an entrance lens (181) into which an LED beam emitted from the first illuminator (120) is incident, and an exit lens (182) that projects the LED beam passing through the entrance lens (181) to a beam splitter (170).

[0049] In addition, the FPM device (100) of the present invention includes a control unit (110) that controls the first LED (122) to emit light sequentially starting from the first LED (122) located at the center point of the first panel (121) of the first illuminator (120), and the first LED (142) to emit light sequentially starting from the second LED (142) located at the center point of the second panel (141) of the second illuminator (140).

[0050] And, the control unit (110) performs control to position each image beam in the spectrum domain and stitch them to produce a composite image having phase information of the measurement object (1).

[0051] At this time, the FPM device (100) of the present invention includes a prism (190) positioned between the objective lens (130) and the measurement object (1), and reflects the LED beam emitted from the second illuminator (140) and irradiates it onto the measurement object (1). The configuration of the prism (190) will be described in more detail below.

[0052] Meanwhile, the unexplained symbol L1 is the optical path of the LED beam emitted from the first LED light source (122) of the first illuminator (120), and the unexplained symbol L2 is the optical path of the LED beam emitted from the second LED light source (142) of the second illuminator (140).

[0053]

[0054] FIG. 3 is a detailed view of the prism of the FPM device of the present invention, and FIG. 4 is a drawing showing the reflection state of a beam irradiated to a measurement target by the prism of the FPM device of the present invention.

[0055] Referring to FIG. 3, the prism (190) is composed of an incident surface (191) onto which an LED beam emitted from a second LED (142) of the second illuminator (140) is incident, a first reflective surface (192) that reflects the LED beam incident through the incident surface (191) upwards, and a second reflective surface (193) that reflects the LED beam reflected upwards by the first reflective surface (192) downwards, and the LED beam reflected by the second reflective surface (193) passes through the first reflective surface (192) and is irradiated to the measurement target (1).

[0056] Referring to FIG. 4, the prism (190) forms a first reflection angle (a1, a2, a3, ...., aN), which is an angle at which the LED beam incident from each different second LED (142) of the second illuminator (140) is reflected by the first reflection surface (192), in order to reflect the LED beam upward by the first reflection surface (192) as described above.

[0057] In addition, the prism (190) has a second reflection angle (b1, b2, b3, ...., bN), which is an angle at which the LED beam reflected upward by the first reflection surface (192) is reflected by the second reflection surface (193), in order to reflect the LED beam downward by the second reflection surface (193) as described above.

[0058] The angles of the first reflection angle (a1, a2, a3, ...., aN) by the first reflection surface (192) and the second reflection angle (b1, b2, b3, ...., bN) by the second reflection surface (193) can be formed arbitrarily as needed, and in the embodiment of the present invention, the first reflection angle (a1, a2, a3, ...., aN) by the first reflection surface (192) is formed at an angle for total reflection upward of the LED beam incident on the incident surface (191), and the angle of the second reflection angle (b1, b2, b3, ...., bN) by the second reflection surface (193) is formed at an angle for reflecting downward the LED beam reflected by the first reflection surface (192), and the LED beam reflected downward by the second reflection surface (193) is formed at the first It is irradiated to the measurement target (1) by penetrating the reflective surface (192).

[0059]

[0060] Hereinafter, the operation of the FPM device (100) of the present invention configured as described above will be described in detail, with reference to each of the drawings described above.

[0061] First, the control unit (110) of the FPM device (100) of the present invention controls the first LED light sources (122) on the first LED panel (121) to emit light sequentially, starting from the first LED light source (122) located at the center point of the first panel (121) of the first illuminator (120).

[0062] Then, the LED beam emitted by the first LED light sources (122) of the first illuminator (120) passes through an optical system (180) composed of an entrance lens (181) and an exit lens (82), is reflected by a beam splitter (170), passes through an objective lens (130), and is irradiated onto the measurement target (1).

[0063] Then, after irradiating the measurement object (1), the imaging beam reflected from the measurement object (1) is focused on the back focal plane of the objective lens (130), and the focused image beam passes through the beam splitter (170) again and is focused on the condenser lens (150), and the focused imaging beam is received by the photodetector (160).

[0064] Next, the control unit (110) acquires an image for each of the imaging beams received by the photodetector (160), performs a fast Fourier transform on each acquired image, and stitches the images to position them at the corresponding positions of θx and θy in the spectral domain to calculate the phase.

[0065] Next, the control unit (110) of the FPM device (100) drives the second illuminator (140).

[0066] Then, starting from the second LED light source (142) located at the center point of the second panel (141) of the second lighting device (140), the second LED light sources (142) on the second LED panel (141) sequentially emit light, and are incident on the incident surface (191) of the prism (190) and reflected upward at an angle of the first reflection angle (a1, a2, a3, ...., aN) by the first reflection surface (192).

[0067] Next, the LED beam reflected upward by the first reflective surface (192) is reflected downward by the second reflective surface (193) at an angle of the second reflection angle (b1, b2, b3,..., bN) and passes through the first reflective surface (192) to be irradiated to the measurement object (1).

[0068] Then, after irradiating the measurement object (1), the imaging beam reflected from the measurement object (1) is focused on the back focal plane of the objective lens (130), the focused image beam passes through the beam splitter (170) again and is focused on the condenser lens (150), and the focused imaging beam is received by the photodetector (160).

[0069] Then, the control unit (110) acquires an image for each imaging beam received by the photodetector (160), performs a fast Fourier transform on each acquired image, and stitches the images to position them at the corresponding positions of θx and θy in the spectral domain to calculate the phase.

[0070] Next, the control unit (110) obtains a spectrum by performing an inverse Fourier transform on the images acquired by each LED beam of the first illuminator (120) and the second illuminator (140), and obtains phase information by converging the phase through an overlapping area, thereby generating a composite image having phase information using the images acquired by the first illuminator (120) and the second illuminator (140), thereby enabling precise measurement of the surface of the measurement object (1).

[0071] Accordingly, the FPM device (100) of the present invention, which operates as described above, can secure a large space for irradiating the measurement object (1) since the second illuminator (140) is located above the measurement object (1), so that a measurement object with a large area can be easily measured at once, thereby shortening the inspection time of the semiconductor, and thereby improving the production efficiency in the semiconductor process.

[0072] In addition, since the distance between the second illuminator (140) and the measurement object (1) is sufficiently secured, the distance between the second illuminator (140) and the measurement object (1) can be secured as a sufficient distance to satisfy the coherent illumination condition, thereby obtaining the effect of performing semiconductor inspection more accurately.

[0073] The reflective FPM device of the present invention having the above configuration has a second illuminator positioned above the measurement target, so that a large space for irradiating the measurement target can be secured, and thus a measurement target with a large area can be easily measured at once, thereby shortening the inspection time of semiconductors and thereby improving production efficiency in semiconductor processes.

[0074] In addition, since a sufficient distance is secured between the second illuminator and the measurement target, the distance between the second illuminator and the measurement target can be secured at a distance sufficient to satisfy the coherent illumination condition, thereby obtaining the effect of performing semiconductor inspection more accurately.

Claims

1. In an FPM device for measuring the surface of a measurement target (1), A first illuminator (120) having a plurality of first LED light sources (122) arranged on a first panel (121) and sequentially irradiating the measurement target (1) at different angles, A second illuminator (140) having a plurality of second LED light sources (142) arranged on a second panel (141) and sequentially irradiating the measurement target (1) at different angles after irradiation by the first illuminator (120), An objective lens (130) that illuminates the LED beams emitted from the first illuminator (120) and the second illuminator (140) onto the measurement target (1) and forms an image of the reflected imaging beams, An FPM device characterized in that it comprises a prism (190) positioned between the objective lens (130) and the measurement object (1), and reflecting the LED beam emitted from the second illuminator (140) and irradiating it onto the measurement object (1).

2. In paragraph 1, A beam splitter (170) that reflects the LED beam emitted from the first illuminator (120) toward the measurement target (1), A condenser lens (150) that condenses the imaging beam formed on the objective lens (130), An FPM device characterized by comprising a photodetector (160) that acquires an image of a measurement object (1) from imaging beams focused on the above-mentioned focusing lens (150).

3. In paragraph 1, An FPM device characterized by a configuration including a control unit (110) that controls the first LED (122) to emit light sequentially starting from the first LED (122) located at the center point of the first panel (121) of the first illuminator (120) and the first LED (142) to emit light sequentially starting from the second LED (142) located at the center point of the second panel (141) of the second illuminator (140).

4. In paragraph 1, An FPM device characterized by a configuration in which the first panel (121) has a circular flat plate shape and a plurality of first LED light sources (122) are arranged in a ring shape radially from the center point of the first panel (121), and the second panel (141) has a circular flat plate shape and a plurality of second LED light sources (142) are arranged in a ring shape radially from the center point of the second panel (141).

5. In the first paragraph, the prism (190) An FPM device characterized by a configuration comprising an incident surface (191) onto which an LED beam emitted from a second LED (142) of the second illuminator (140) is incident, a first reflection surface (192) that reflects the LED beam incident through the incident surface (191) upwards, and a second reflection surface (193) that reflects the LED beam reflected upwards by the first reflection surface (192) downwards.

6. In the fifth paragraph, the prism (190) An FPM device characterized by a configuration in which a first reflection angle (a1, a2, a3, ...., aN) is formed, which is an angle at which an LED beam incident from each of the different second LEDs (142) of the second illuminator (140) is reflected by the first reflection surface (192), and the first reflection angle (a1, a2, a3, ...., aN) by the first reflection surface (192) is formed at an angle for totally reflecting the LED beam incident on the incident surface (191) upward.

7. In the 6th paragraph, the prism (190) An FPM device characterized in that a second reflection angle (b1, b2, b3, ...., bN) is formed, which is an angle at which an LED beam reflected upward by the first reflection surface (192) is reflected by the second reflection surface (193), and the second reflection angle (b1, b2, b3, ...., bN) by the second reflection surface (193) is formed at an angle for reflecting the LED beam reflected by the first reflection surface (192) downward.

Images