JP2006194978A - Microscopic observation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microscopic observation device efficiently performing the observation of a substrate by an immersion method by easily and rapidly supervising the progressing conditions of removing liquid which is supplied to the observing points of the substrate. <P>SOLUTION: The microscopic observation device is equipped with: a means 21 supporting the substrate 10A being an observation object, an immersion objective 24; a means 40 generating a focus signal in accordance with the focusing state of the substrate with respect to the focal position of the objective; a means 50 adjusting the relative position of the objective to the substrate based on the focus signal after supplying the liquid between the edge of the objective and the observing point of the substrate, a removing means removing the liquid after finishing the observation of the substrate; and a supervisory means 50 supervising the progressing conditions of removing the liquid based on the focus signal in the midst of removing the liquid by the removing means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a microscope observation apparatus used for immersion observation of an object, and more particularly to a microscope observation apparatus suitable for immersion observation of a semiconductor wafer or a liquid crystal substrate.

In a manufacturing process of a semiconductor circuit element or a liquid crystal display element, a circuit pattern formed on a semiconductor wafer or a liquid crystal substrate (generally referred to as “substrate”) is observed for defects, foreign matters, and the like using a microscope observation apparatus. The microscope observation apparatus is a combination of a mechanism for automatically transporting a substrate and an optical microscope system. The objective lens of the optical microscope system is a dry system, and the gap between the objective lens and the substrate to be observed is filled with a gas such as air (see, for example, Patent Document 1). In order to realize observation with higher resolution, it has been proposed to set the observation wavelength to the ultraviolet region.
JP 2001-118896 A

  By the way, in an apparatus using a dry objective lens, the numerical aperture of the objective lens cannot be made larger than “1”, so that there is a limit to improvement in resolution. Therefore, it is conceivable to use a known immersion method and use an immersion-type objective lens in place of the dry-type objective lens. By using an immersion objective lens and filling the space between the tip and the substrate to be observed with a liquid such as water, the numerical aperture of the objective lens is “1” according to the refractive index (> 1) of the liquid. It can be made larger and the resolution can be improved.

  However, simply exchanging the objective lens from a dry system to an immersion system cannot efficiently observe the substrate in the above manufacturing process. In order to perform the observation efficiently, a mechanism for removing the liquid supplied between the tip of the immersion objective lens and the observation point of the substrate after the observation is necessary. It is also desirable to monitor the progress of liquid removal at the current observation point in order to move to the next observation point as soon as possible, but an effective monitoring method has not yet been proposed. As the simplest monitoring method, for example, a visual method is conceivable. However, since the distance between the tip of the objective lens and the observation point of the substrate is very narrow, it takes a long time for visual recognition.

  An object of the present invention is to provide a microscope observation apparatus that can easily and quickly monitor the progress of a liquid supplied to an observation point of a substrate and can efficiently observe a substrate by an immersion method. There is to do.

  The microscope observation apparatus according to claim 1 generates a focus signal according to a support unit that supports a substrate to be observed, an immersion objective lens, and a focus state of the substrate with respect to a focal position of the objective lens. And generating means for adjusting the relative position between the objective lens and the substrate based on the focus signal after the liquid is supplied between the tip of the objective lens and the observation point of the substrate; And removing means for removing the liquid after the observation of the substrate, and monitoring means for monitoring the progress of the liquid removal based on the focus signal during the removal of the liquid by the removing means. .

According to a second aspect of the present invention, in the microscope observation apparatus according to the first aspect, the removing unit is a unit that sucks the liquid, and the monitoring unit is configured to perform the removal according to an abnormality in the focus signal. The liquid suction operation by the means is stopped.
The invention according to claim 3 is the microscope observation apparatus according to claim 2, further comprising a blowing means for drying the liquid by blowing air toward the liquid and / or the periphery of the liquid, The monitoring means stops the suction operation by the removing means and then starts the drying operation of the liquid by the blowing means.

  The invention according to claim 4 is the microscope observation device according to claim 2, further comprising a blowing means for drying the liquid by blowing air toward the liquid and / or the periphery of the liquid, The monitoring unit starts the drying operation of the liquid by the blowing unit after the observation of the substrate is completed and before the suction operation by the removing unit is stopped.

  According to a fifth aspect of the present invention, in the microscope observation apparatus according to the third or fourth aspect, the monitoring unit stops the suction operation by the removing unit and then blows the blowing unit for a predetermined time. The drying operation is continued.

  According to the microscope observation apparatus of the present invention, when the liquid supplied to the observation point of the substrate is removed, the progress can be monitored easily and quickly, and the substrate can be efficiently observed by the immersion method. Can do.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
As shown in FIGS. 1 (a), 1 (b) and 2, the microscopic observation apparatus 10 of the first embodiment includes a mini-environment device (11-14, 16-19) and a liquid immersion installed therein. The microscope 20 and the blower 30 are configured. 1A is a top view of the microscope observation apparatus 10, and FIGS. 1B and 2 are cross-sectional views. Further, a mechanism (not shown) for automatically transporting the substrate 10A to be observed is provided inside the mini-environment device (11-14, 16-19). The substrate 10A is a semiconductor wafer or a liquid crystal substrate. The microscope observation apparatus 10 is used for liquid immersion observation (appearance inspection) of a circuit pattern defect or foreign matter formed on the substrate 10A in a manufacturing process of a semiconductor circuit element or a liquid crystal display element. The circuit pattern is, for example, an etching pattern.

  The mini-environment devices (11-14, 16-19) will be described. The mini-environment devices (11 to 14, 16 to 19) are installed on the casing 11, the partition plate 12, the surface plate 13, the pressure adjusting mechanism 14 installed in the casing 11, and the upper surface 11A of the casing 11. It comprises a plurality of fan filter units 16-19. A vent hole (not shown) is formed on the lower surface 11 </ b> B of the housing 11. The inside of the housing 11 is a local environment (minienvironment) in which the immersion observation of the substrate 10A is performed, and the cleanliness is higher than the surroundings (in the clean room).

  The interior of the housing 11 is divided into three spaces A, B, and C by a partition plate 12 in the vertical direction and a surface plate 13 in the horizontal direction. That is, the upper surface 11A side of the surface plate 13 is divided into two spaces A and B by the partition plate 12, and the lower surface 11B side of the surface plate 13 forms one space C. In the space A, the immersion microscope 20 and the blower 30 are accommodated, in the space B, a transport system (not shown) for the substrate 10A is accommodated, and in the space C, for example, a computer or the like is accommodated.

  The platen 13 is a plate-like member that supports the immersion microscope 20 and the transport system (not shown) of the substrate 10A. The platen 13 has a vent opening 13A at a location facing the partition member 12 and has an end. There are similar openings 13B and 13C in the part. Furthermore, the pressure adjusting mechanism 14 provided in the same horizontal plane as the surface plate 13 is provided with an opening for ventilation whose size can be adjusted. Further, the partition plate 12 is provided with an opening 12A for passage of the substrate 10A conveyed by the conveyance system. The substrate 10A is transferred from the space B to the space A via the opening 12A, and when the immersion observation by the immersion microscope 20 is completed, the substrate 10A is recovered from the space A to the space B via the opening 12A.

  The fan filter units 16 to 19 are installed on the upper surface 11 </ b> A of the housing 11, and after removing fine particles in the gas such as dust and dust from the surrounding (inside the clean room) air, clean air is supplied to the interior of the housing 11. (FFU: FAN FILTER UNIT). Of the fan filter units 16 to 19, one fan filter unit 16 introduces clean air toward the space A inside the housing 11. Further, the remaining three fan filter units 17 to 19 introduce clean air toward the space B inside the housing 11.

  Each of the fan filter units 16 to 19 includes fans 16A to 19A as downflow blowing means for blowing air from the upper surface 11A of the housing 11 toward the inside of the housing 11 (space A, space B). Provided. Furthermore, dust-preventing ULPA filters (Ultra Low Penetoration Air Filters) 16B to 19B are attached to all the fan filter units 16 to 19, respectively, so as to cover the air outlets. The fan 19A and the ULPA filter 19B of the fan filter unit 19 are not shown.

  In addition, a chemical filter 16 </ b> C is attached to the fan filter unit 16 in the upper part of the space A so as to cover its outlet in order to protect the optical system of the immersion microscope 20 installed in the space A. The chemical filter 16C is a combination of a filter that removes organic gas, a filter that removes alkaline gas (for example, ammonia gas), and a filter that removes acid gas, and is disposed between the fan 16A and the ULPA filter 16B. Is done. Note that the filter for removing the acid gas may be omitted.

  In the mini-environment device (11 to 14, 16 to 19) configured as described above, in the space A in the housing 11, minute particles in the gas such as dust and dust are removed by the ULPA filter 16B. In addition, clean air from which chemical substances (organic gas, ammonia gas, etc.) are removed by the chemical filter 16C is blown out by the fan 16A. In the space B, clean air from which fine particles in the gas such as dust and dust are removed by the ULPA filters 17B to 19B is blown out by the fans 17A to 19A.

  The air blown into the spaces A and B from the upper surface 11A of the housing 11 flows downward (downflow), and passes through the openings 13A to 13C for ventilation of the surface plate 13 and the vent of the pressure adjusting mechanism 14. Through the surface plate 13 to reach the space C on the lower surface 11B side. Then, it flows further downward and is exhausted to the outside of the housing 11 (inside the clean room) through a vent (not shown) on the lower surface 11B. In addition, the arrow of FIG. 1 represents the flow of air. Thus, by using the mini-environment device (11-14, 16-19), the high cleanliness required for the immersion observation of the substrate 10A can be obtained at a lower cost than the overall cleanliness in the clean room. Can be realized.

  Further, in the mini-environment devices (11 to 14, 16 to 19), along the partition plate 12 by the opening 13A provided just below the partition plate 12 (a part of the surface plate 13 facing the partition plate 12). The air flowing downward can be smoothly led to the space C without being disturbed. Further, by adjusting the size of the vent of the pressure adjusting mechanism 14 and making the internal pressure P1 of the space A higher than the internal pressure P2 of the space B, the flow direction of the air in the spaces A and B can be changed. It can be set to flow from the space A side to the space B side through the opening 12A.

  Therefore, even when the spaces A and B are connected via the opening 12A of the partition plate 12, the air blown into the space B (air containing organic gas) spreads into the space A via the opening 12A. There seems to be almost nothing. For this reason, the space A can be stably filled with air from the fan filter unit 16 (air that does not contain organic gas). That is, it is possible to create an environment with a low outgas such as TOC (Total Organic Carbon) locally. As a result, in the space A, a chemical reaction between the inspection light (for example, deep ultraviolet light) passing through the optical system of the immersion microscope 20 and the organic gas does not occur, and the optical system (for example, a film on the lens surface). Can be protected.

  Next, the immersion microscope 20 in the space A will be described. As shown in FIG. 3, the immersion microscope 20 includes a stage unit (21, 22) that supports the substrate 10 </ b> A to be observed, an immersion observation optical system (24, 25), a liquid feeder 26, A liquid suction machine 27 is provided. The immersion microscope 20 is also provided with an illumination optical system including an illumination light source 29 shown in FIG. 2, a TTL autofocus (AF) mechanism 40 and a control unit 50 shown in FIG.

  The stage section (21, 22) is composed of a syringe (not shown), a Zθ stage 21, and an XY stage 22. The syringe is supported so as to be movable in the vertical direction by the Zθ stage 21 and movable in a horizontal plane by the XY stage 22. The substrate 10A is conveyed from, for example, the developing device and placed on the upper surface of the syringe, and is fixedly supported by, for example, vacuum suction. The Zθ stage 21 moves the syringe in the vertical direction when the substrate 10A is focused. The focusing operation is performed by the control unit 50 using the AF mechanism 40. Further, when positioning a predetermined observation point of the substrate 10A within the visual field of the observation optical system (24, 25), the XY stage 22 moves the Zθ stage 21 within a horizontal plane. The base member of the XY stage 22 is fixed to the main body of the immersion microscope 20.

  The observation optical system (24, 25) is provided with an immersion objective lens 24, an eyepiece lens 25, and the like. The objective lens 24 and the eyepiece lens 25 are fixed to the main body of the immersion microscope 20. The objective lens 24 is designed so that the aberration of the optical system is corrected when the space between the tip (lower surface) and the substrate 10A is filled with the immersion medium (liquid 28). The tip of the objective lens 24 becomes a contact portion with the liquid 28.

  The illumination optical system is provided with an illumination light source 29 shown in FIG. The observation wavelength is, for example, a visible region or an ultraviolet region. When the illumination light source 29 having a visible wavelength is used, the immersion observation of the substrate 10A using the eyepiece lens 25 can be performed. However, when an illumination light source 29 having a wavelength in the ultraviolet region is used, observation from the eyepiece lens 25 is not possible. Therefore, a CCD camera or the like is provided in place of the eyepiece lens 25, and a live image is displayed on the monitor device for observation. To do.

  The liquid supply unit 26 is a mechanism for supplying the liquid 28 of the immersion medium to the observation point of the substrate 10A, and includes a discharge nozzle, a pressure pump, a liquid tank, and the like. The discharge nozzle is disposed in the vicinity of the periphery of the objective lens 24, and the tip thereof is disposed in the vicinity of the tip of the objective lens 24. The pressurizing pump sends a predetermined amount of liquid from the liquid tank to the discharge nozzle. As a result, the liquid 28 discharged from the tip of the discharge nozzle reaches (space) between the tip of the objective lens 24 and the substrate 10A. In this way, the liquid 28 is supplied through the discharge nozzle, and “droplets” are formed by the surface tension. The supply of the liquid 28 is automatically performed by the control unit 50 before the immersion observation.

The AF mechanism 40 is disposed on the optical axis of the objective lens 24 as shown in FIG. The AF mechanism 40 detects the in-focus state (defocus amount) of the substrate 10A with respect to the focal position of the objective lens 24 at least during immersion observation of the substrate 10A, and a focus signal (AF) according to the in-focus state of the substrate 10A. Signal).
In the AF mechanism 40, the light from the light source 41 is irradiated onto the slit 42, and the light is made substantially parallel by the lens 43 and is incident on the light shielding plate 44. The light shielding plate 44 shields half of the light that has passed through the slit 42. The light that has passed through the light shielding plate 44 is reflected by the branching prisms 45 and 46 and guided to the objective lens 24. As a result, a slit image is projected onto the substrate 10A.

  The light reflected by the substrate 10 </ b> A (AF detection light) is again collected by the objective lens 24, passes through the branching prisms 46 and 45, and is collected by the imaging lens 47. As a result, a slit image is formed on the one-dimensional image sensor 48. The signal processing unit 49 detects the position of the center of gravity of the slit image in the one-dimensional image sensor 48, obtains the defocus amount of the substrate 10 </ b> A from the position, and outputs the focus signal to the control unit 50.

  The controller 50 controls the Zθ stage 21 based on the focus signal output from the AF mechanism 40 after the liquid 28 is supplied between the tip of the objective lens 24 and the observation point of the substrate 10A, and the objective lens The relative position between the substrate 24 and the substrate 10A is automatically adjusted (AF control). At this time, the Zθ stage 21 is controlled based on the corrected focus signal by correcting the focus signal from the AF mechanism 40 with the refractive index of the immersion medium (liquid 28).

  In immersion observation of the substrate 10A using the objective lens 24 and the eyepiece lens 25 (or a CCD camera not shown) of the immersion microscope 20, the liquid 28 is supplied to the observation point of the substrate 10A, and the substrate 10A is the objective lens. It is performed in a state of being positioned on the 24 focal planes. Further, the immersion observation of the substrate 10A is performed in a downflow environment by the fan filter units 16-19. During this immersion observation, the space A is filled with air that does not contain an organic gas, and the immersion microscope 20 is used in a clean environment. Therefore, the optical system (such as the objective lens 24) of the immersion microscope 20 is surely provided. Can protect.

  In the immersion microscope 20, an enlarged image (pattern image) of the substrate 10A is formed at the visual field position of the eyepiece lens 25 (or the imaging surface of the CCD camera), and the substrate 10A is observed using this image. Further, the numerical aperture of the objective lens 24 can be made larger than “1” in accordance with the refractive index (> 1) of the liquid 28 that fills between the tip of the objective lens 24 and the observation point of the substrate 10A. The resolution can be reliably improved as compared with the apparatus (numerical aperture of objective lens ≦ 1).

  Incidentally, the resolution is expressed as “resolution = k × λ / NA” by using the numerical aperture NA of the objective lens 24, the observation wavelength λ, and the constant k. When discussing the resolution between two points, the value of the constant k is normally “0.61”. The numerical aperture NA of the objective lens 24 is expressed as “NA = n × sin θ” using the opening angle θ of the objective lens 24 and the refractive index n of the medium between the objective lens 24 and the substrate 10A. The Thus, the resolution decreases (increases) in inverse proportion to the increase in the refractive index n between the objective lens 24 and the substrate 10A.

  For example, pure water is used as the liquid 28 of the immersion medium. Pure water can be easily obtained in large quantities in a semiconductor manufacturing process or the like. Further, since there is no adverse effect on the photoresist on the substrate 10A, a nondestructive inspection of the substrate 10A can be performed. In addition, pure water has no adverse effect on the environment, and since the content of impurities is extremely low, an effect of cleaning the surface of the substrate 10A can be expected. Pure water used in the semiconductor manufacturing process is generally called “ultra pure water”. This is higher in purity than what is generally called “pure water” and has a specific resistance of 18.2 MΩ · cm or more. Also in this embodiment, it is more preferable to use ultrapure water.

  The liquid suction device 27 is a mechanism for sucking the liquid 28 of the immersion medium from the observation point of the substrate 10A after the observation of the substrate 10A, and includes a suction nozzle, a suction pump, a waste liquid tank, and the like. The suction nozzle is disposed in the vicinity of the periphery of the objective lens 24, and the tip thereof is disposed in the vicinity of the tip of the objective lens 24. The suction pump sucks the liquid 28 between the tip of the objective lens 24 and the substrate 10A together with the surrounding air through the suction nozzle. That is, the liquid 28 is removed from the substrate 10A. The sucked liquid 28 is separated from air by a filter, for example, and collected in a waste liquid tank. Thus, the liquid 28 is sucked through the suction nozzle. The suction of the liquid 28 is automatically performed by the control unit 50 after the immersion observation.

  Next, the blower 30 will be described. As shown in FIG. 2, the blower 30 includes a liquid drying fan 30 </ b> A disposed in the vicinity of the immersion microscope 20 and a dust generation prevention (particle removal) ULPA filter 30 </ b> B attached to the blowout port. And a duct 30C. The duct 30 </ b> C is disposed between the fan 30 </ b> A and the illumination light source 29 of the immersion microscope 20. The illumination light source 29 is considered a heat source.

  In the blower 30, the air heated by the illumination light source 29 using the remaining heat of the illumination light source 29 (air having a higher temperature than the liquid 28 (warm air)) is supplied to the intake port on the upstream side of the fan 30 </ b> A via the duct 30 </ b> C. Lead to. Then, warm air can be blown out from the side of the objective lens 24 toward the liquid 28 and / or the periphery of the liquid 28 (laterally) through the ULPA filter 30B by the fan 30A.

  Next, the observation operation of the substrate 10A in the microscope observation apparatus 10 of the first embodiment will be described. The observation operation of the substrate 10A is automatic control by the control unit 50, and is performed according to the procedure of the flowchart shown in FIG. The immersion observation using the microscope observation apparatus 10 corresponds to, for example, an appearance inspection for confirming the cause and the state of a defect or a foreign object detected by another defect inspection apparatus.

  First (step S1), the substrate 10A to be observed is transported to the stage portions (21, 22) of the immersion microscope 20 and fixed to the upper surface of the syringe. Next (step S2), the Zθ stage 21 and the XY stage 22 are controlled to position a predetermined observation point on the substrate 10A within the field of view of the objective lens 24. Next (step S3), the liquid supplier 26 is controlled to supply a predetermined amount of liquid 28 between the tip of the objective lens 24 and the observation point of the substrate 10A. Note that the order of steps S2 and S3 may be reversed. That is, after placing the liquid 28 on the observation point of the substrate 10 </ b> A, this observation point may be positioned in the field of view of the objective lens 24.

After the liquid 28 is supplied between the tip of the objective lens 24 and the observation point of the substrate 10A, the control unit 50 proceeds to the process of step S4 and starts AF control. That is, the Zθ stage 21 is controlled based on the focus signal from the AF mechanism 40 to position the substrate 10A on the focal plane of the objective lens 24. The AF control is continued until step S8 described later.
With the substrate 10A positioned on the focal plane of the objective lens 24, it is possible to perform immersion observation (that is, observation with high resolution) of the substrate 10A in step S5. The observer performs immersion observation of the observation point of the substrate 10A with the eyepiece lens 25 (or a monitor device connected to a CCD camera (not shown)). When a CCD camera is used for immersion observation, an observation image may be captured.

  Thereafter, when the immersion observation of the substrate 10 </ b> A is completed, an observation end signal is output to the control unit 50. When the immersion observation of the substrate 10A is performed by the eyepiece lens 25, the observation end signal is output when a button for notifying the controller 50 of the observation end is operated by the observer. When a CCD camera is used for the immersion observation of the substrate 10A, the observation end signal is output at the timing when the capturing of the observation image by the CCD camera is completed.

  When receiving the observation end signal, the control unit 50 proceeds to the next step S6, controls the liquid suction device 27, and starts the operation of sucking the liquid 28 from between the tip of the objective lens 24 and the substrate 10A. Further, in the next step S 7, it is determined whether the focus signal from the AF mechanism 40 is normal or abnormal during the suction (removal) of the liquid 28 by the liquid suction device 27. That is, the progress of liquid removal is monitored based on the focus signal.

  The progress of the liquid removal is schematically shown as in FIGS. 6 (a) → (b) → (c). That is, from the start of suction (a) to halfway (b), the surface tension keeps the space between the tip of the objective lens 24 and the substrate 10A filled with the liquid 28, but further liquid removal proceeds. In the last (c), it is considered that the air layer 8A enters between the tip of the objective lens 24 and the substrate 10A.

  The focus signal from the AF mechanism 40 is normal when the tip of the objective lens 24 and the substrate 10A are filled with the liquid 28 (the state in which the air layer 8A is not included as shown in FIG. 6C). Vary within range. Therefore, for a while after the start of the liquid removal (FIGS. 6A and 6B), the determination result in step S7 in FIG. 5 is Yes, and the liquid removal operation by the liquid suction device 27 continues. Is called.

  However, when the remaining amount of the liquid 28 is reduced and the air layer 8A (FIG. 6C) enters the liquid 28, the refractive index between the tip of the objective lens 24 and the substrate 10A changes. The focus signal from 40 is out of the normal range so far and shows an abnormal value. Therefore, according to the abnormality of the focus signal, the determination result of step S7 in FIG. 5 is No, and the control unit 50 proceeds to the next step S8.

In step S <b> 8, the control unit 50 stops the suction operation of the liquid 28 by the liquid suction machine 27. If the focus signal indicates an abnormal value, the substrate 10A cannot be positioned (focused) on the focal plane of the objective lens 24 even if the Zθ stage 21 is controlled based on the focus signal. Stop.
At this time, there is a possibility that the trace amount of liquid 28 may not be completely removed between the tip of the objective lens 24 and the substrate 10A. As shown in FIG. 7, the portions where the remaining liquid (a trace amount) is attached are the portions 8B and 8C that are in contact with the liquid 28 at the time of observation, and the tip of the objective lens 24 (particularly, the tip of the tip lens 24A) 10A observation point and the like. If the liquid is left in these places 8B and 8C, the tip of the objective lens 24 (particularly, the front lens 24A) may be deteriorated and the observation point of the substrate 10A may be melted.

  Then (step S9), the control unit 50 controls the fan 30A of the blower 30 so that the air (warm air) heated by the illumination light source 29 is supplied from the side of the objective lens 24 with the liquid 28 and / or liquid. The remainder of the liquid 28 is dried by blowing out toward the periphery of 28 (sideways). The liquid drying operation by the fan 30A of the blower 30 is continuously performed for a predetermined time from the start.

  The operating time of the fan 30A (the above-mentioned predetermined time) is (1) the amount of remaining liquid after suction according to the supply amount of the liquid 28 by the liquid supply device 26 and the suction performance of the liquid 28 by the liquid suction device 27. (2) Approximate the time required for drying the remaining amount according to the amount of remaining liquid, the air blowing speed from the fan 30A, and the temperature of the air, and use this time as the operation of the fan 30A. What is necessary is just to determine as time.

  In this way, after the suction operation by the liquid suction device 27 is stopped, the drying operation by the fan 30A of the blower 30 is started and continued for a predetermined time, so that the suction by the liquid suction device 27 is removed. The liquid 28 that cannot be removed can be forcibly and efficiently removed by drying. When the air flow direction is set to the horizontal direction, the wind directly hits the remaining liquid, so that drying can be accelerated. Moreover, the liquid can be dried more effectively by using warm air.

  When the drying process in step S9 is completed, the control unit 50 determines that the removal of the liquid 28 supplied to the observation point of the substrate 10A is complete (that is, the stage unit (21, 22) is movable), and the process in step S10. Proceed to In step S10, it is determined whether or not there is a next observation point on the substrate 10A. If there is one (S10 is Yes), the process returns to step S2. In step S2, the stage portions (21, 22) are controlled to move to the next observation point. On the other hand, when there is no next observation point (S10 is No), it progresses to step S11, collect | recovers board | substrate 10A from a stage part (21,22), and complete | finishes the observation operation of board | substrate 10A.

  As described above, in the microscope observation apparatus 10 according to the first embodiment, when the liquid 28 supplied to the observation point of the substrate 10A is removed, the focus signal from the AF mechanism 40 is used to determine whether the focus signal is normal / abnormal. Since the progress of the liquid removal is monitored based on the above (step S7 in FIG. 5), the monitoring can be performed easily and quickly. Therefore, it is possible to move to the next observation point as soon as possible without scattering the liquid around the current observation point, and the substrate 10A can be efficiently observed by the immersion method.

  Further, in the microscope observation apparatus 10 of the first embodiment, the suction operation by the liquid suction device 27 is stopped in accordance with the abnormality of the focus signal from the AF mechanism 40, so that the suction performance of the liquid suction device 27 does not deteriorate. The liquid suction machine 27 can be used efficiently. In general, when the remaining amount of the liquid 28 between the tip of the objective lens 24 and the substrate 10A is reduced and the air layer 8A (FIG. 6C) enters the liquid 28, the liquid 28 is removed by the liquid suction device 27. Suction becomes difficult (decrease in suction performance).

  Furthermore, in the microscope observation apparatus 10 according to the first embodiment, after the suction operation by the liquid suction device 27 is stopped, the drying operation by the fan 30A of the blower 30 is started and is continued for a predetermined time. The liquid 28 can be forcibly and efficiently removed by drying. At this time, not only the liquid adhering to the tip of the objective lens 24 (particularly, the tip of the leading ball lens 24A) and the observation point of the substrate 10A but also the liquid spilling from the substrate 10A and adhering to the Zθ stage 21 or the like is dried. Can do.

Moreover, in the microscope observation apparatus 10 of the first embodiment, when removing the liquid 28, the suction using the liquid suction device 27 and the drying using the fan 30A of the blower 30 are used in combination, so the observation of the substrate 10A is performed. After completion, the liquid 28 can be removed instantaneously.
As the time during which the liquid 28 is in contact with the tip of the objective lens 24 or the observation point of the substrate 10A is shorter, the deterioration of the objective lens 24 and the dissolution of the substrate 10A are less likely to occur. That is, the objective lens 24 and the substrate 10A (fine pattern) can be protected. Further, the generation of contaminants due to the deterioration of the objective lens 24 and the dissolution of the substrate 10A can be minimized.

Therefore, the immersion observation can be performed without destroying the substrate 10A, and the observation can be performed at a high speed with 1 / n times higher resolution. In addition, the life of the objective lens 24 can be extended.
Furthermore, in the microscope observation apparatus 10 of the first embodiment, since the fan 30A of the blower 30 is operated only after the liquid is sucked, dust caused by a movable part (for example, the stage parts (21, 22)) of the immersion microscope 20 is removed. It is also possible to reduce the influence of scattering.

Further, in the microscope observation device 10 of the first embodiment, the immersion microscope 20 is housed inside the mini-environment device (11-14, 16-19), and thus blown out into the space A by the fan 16A of the fan filter unit 16. The air (downflow) thus made also reaches the liquid 28 and / or the periphery of the liquid 28 supplied to the observation point of the substrate 10A. For this reason, the drying effect of the liquid 28 by the fan 16A can also be expected.
(Second Embodiment)
The microscope observation apparatus of the second embodiment performs an observation operation of the substrate 10A according to the procedure of the flowchart of FIG. 8 instead of the flowchart of FIG. The processes in steps S21 to S25, S30, and S31 in FIG. 8 are the same as the processes in steps S1 to S5, S10, and S11 in FIG. The observation operation of the substrate 10 </ b> A in the second embodiment is also automatic control by the control unit 50.

  When the control unit 50 receives the observation end signal, the control unit 50 performs the process of step S26. That is, the suction operation of the liquid 28 is started by controlling the liquid suction device 27, and at the same time, the drying operation of the liquid 28 is started by controlling the fan 30A of the blower 30. In the next step S27, it is determined whether the focus signal from the AF mechanism 40 is normal or abnormal during the suction and drying (removal) of the liquid 28. That is, the progress of liquid removal is monitored based on the focus signal.

  Then, while the focus signal is kept within the normal range (while the determination result of step S27 is Yes), the liquid removal operation (suction operation and drying operation) is continuously performed. Thereafter, when the remaining amount of the liquid 28 decreases and the air layer 8A (FIG. 6C) enters the liquid 28 and the focus signal deviates from the normal range and shows an abnormal value (No in S27), the control unit In step 50, the process proceeds to step S28.

  In step S <b> 28, the control unit 50 stops the suction operation of the liquid 28 by the liquid suction device 27. If the focus signal indicates an abnormal value, the substrate 10A cannot be positioned (focused) on the focal plane of the objective lens 24 even if the Zθ stage 21 is controlled based on the focus signal. Stop. Further, after a predetermined time has elapsed from the stop of the suction operation, the drying operation by the fan 30A of the blower 30 is also stopped.

  Therefore, in addition to the effect similar to the microscope observation apparatus 10 of 1st Embodiment mentioned above, in the microscope observation apparatus of 2nd Embodiment, there exists the following effect. After the observation of the substrate 10A is finished, the suction operation and the drying operation of the liquid 28 are started at the same time in step S26, so that the liquid 28 can be dried while being sucked, and the liquid 28 is quickly removed from the observation point of the substrate 10A. Can be removed. As a result, the throughput is improved as compared with the microscope observation apparatus 10 of the first embodiment described above.

  In the second embodiment described above, an example in which suction and drying are started simultaneously has been described, but the present invention is not limited to this. As the start timing of suction and drying, suction may be started first, and drying may be started during suction (while the focus signal is normal). Further, drying may be started first, and suction may be started during the drying (while the focus signal is normal). That is, the drying start timing can be set after the observation of the substrate 10A is finished and before the suction is stopped.

In the second embodiment described above, the example in which drying is stopped after a predetermined time from the stop of suction has been described, but the present invention is not limited to this. The drying stop timing may be simultaneous with the suction stop. That is, it is sufficient to continue drying at least until the suction is stopped. In this case, although a trace amount of liquid may be left, the remaining liquid can be removed by the drying effect by the fan 16A of the fan filter unit 16 of the mini-environment device (11-14, 16-19).
(Modification)
In the above-described embodiment, the example in which the progress of the liquid removal is monitored based on the focus signal from the AF mechanism 40 has been described, but the present invention is not limited to this. When the immersion microscope 20 is provided with a CCD camera, a similar focus signal (a signal that changes according to the focus state of the substrate with respect to the focal position of the objective lens 24) is generated based on the image signal from the CCD camera. Can be generated. This generation may be performed by image matching or contrast calculation. For this reason, it is possible to monitor the progress of the liquid removal based on the focus signal generated from the image signal of the CCD camera.

In the above-described embodiment, the example in which the liquid is removed by using the suction and the drying together is described, but the present invention is not limited to this.
(1) The present invention can also be applied to the case where the liquid is removed only by suction. In this case, the suction is started after the observation is finished, and the suction is stopped according to the abnormality of the focus signal. The trace amount of the remaining liquid can be removed by the drying effect by the fan 16A of the fan filter unit 16 of the mini-environment device (11-14, 16-19).

  (2) The present invention can also be applied to the case where the liquid is removed only by drying. In this case, the drying is started after the observation is finished, the time measurement is started according to the abnormality of the focus signal, and the drying is stopped after a predetermined time. For this reason, the liquid can be removed without being left by drying by the blower 30. Alternatively, drying may be started after the observation is finished, and the drying may be stopped in accordance with an abnormality in the focus signal. In this case, it is preferable to remove a trace amount of the remaining liquid by a drying effect by the fan 16A of the fan filter unit 16 of the mini-environment device (11-14, 16-19).

Further, in the above-described embodiment, the example in which the air heated by the illumination light source 29 is blown out from the blower 30 has been described, but the present invention is not limited to this. The duct 30C may be omitted, and unheated air may be blown out.
Furthermore, in the above-described embodiment, the chemical filter 16C is attached to one fan filter unit 16 in the space A, but the present invention is not limited to this. When a plurality of fan filter units are installed in the space A, it is necessary to attach chemical filters to all of them. Further, when one or more fan filter units are installed across the space A and the space B, the blowing port of the fan filter unit is divided to cover at least the blowing portion toward the space A. A filter may be attached.

  In this manner, in the fan filter units 17 to 19 in the space B in which the immersion microscope 20 is not installed (in which the transport system is installed), the chemical filter is omitted and the fan filter unit 16 in the space A in which the immersion microscope 20 is installed. Since only the chemical filter 16C is mounted, the running cost and the initial cost can be surely reduced by reducing the number of chemical filters. However, chemical filters may be attached to all fan filter units. The present invention can also be applied to a case where a high-performance dust collection filter such as a HEPA (High Efficiency Particulate Air Filter) filter is attached instead of the ULPA filter.

2A is a top view of the microscope observation apparatus 10 and FIG. 1 is a longitudinal sectional view of a part (space A) of a microscope observation apparatus 10. FIG. 2 is a schematic diagram showing a configuration of an immersion microscope 20. FIG. 3 is a schematic diagram showing a configuration of an AF mechanism 40. It is a flowchart which shows the procedure of the observation operation | movement in 1st Embodiment. It is a side view which shows the behavior at the time of removing the liquid 28. FIG. It is a figure explaining the places 8B and 8C which contact the liquid 28 at the time of observation. It is a flowchart which shows the procedure of the observation operation | movement in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Microscope observation apparatus 11 Case 12 Partition plate 13 Surface plate 14 Pressure adjustment mechanism 16, 17, 18, 19 Fan filter unit 16A, 17A, 18A, 30A Fan 16B, 17B, 18B, 30B ULPA filter 16C Chemical filter 20 Immersion Microscope 21 Zθ stage 22 XY stage 24 Immersion objective lens 26 Liquid supply machine 27 Liquid suction machine 28 Liquid 8A Air layer 29 Illumination light source 30 Blower 30C Duct 40 AF mechanism 50 Control unit

Claims (5)

Supporting means for supporting the substrate to be observed;
An immersion objective lens;
Generating means for generating a focus signal according to a focus state of the substrate with respect to a focal position of the objective lens;
An adjusting means for adjusting a relative position between the objective lens and the substrate based on the focus signal after liquid is supplied between the tip of the objective lens and the observation point of the substrate;
Removing means for removing the liquid after the observation of the substrate;
A microscope observation apparatus comprising: monitoring means for monitoring the progress of liquid removal based on the focus signal during removal of the liquid by the removal means. In the microscope observation apparatus according to claim 1,
The removing means is means for sucking the liquid;
The monitoring means stops the liquid suction operation by the removing means in response to an abnormality in the focus signal. The microscope observation apparatus according to claim 2,
A blower for drying the liquid by blowing out air toward the liquid and / or the periphery of the liquid;
The said monitoring means stops the said suction operation by the said removal means, Then, the drying operation of the said liquid by the said ventilation means is started. Microscope observation apparatus characterized by the above-mentioned. The microscope observation apparatus according to claim 2,
A blower for drying the liquid by blowing out air toward the liquid and / or the periphery of the liquid;
The said observation means starts the drying operation of the said liquid by the said ventilation means after completion | finish of observation of the said board | substrate and before the said suction operation by the said removal means is stopped. The microscope observation apparatus characterized by the above-mentioned. In the microscope observation apparatus according to claim 3 or claim 4,
The monitoring means continues the drying operation by the blowing means for a predetermined time after stopping the suction operation by the removing means.

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