JP5523041B2 - Imaging device - Google Patents

Description

  The present invention relates to an image pickup apparatus that picks up an image of a workpiece such as a semiconductor wafer or an electronic component substrate.

  For example, a cutting apparatus that cuts this type of workpiece includes a microscope, a CCD camera, or the like in order to detect a region to be cut of the workpiece or to check the state of a groove formed by cutting. An imaging device is equipped. Such an imaging device is generally arranged at a position close to the cutting region.

  In the cutting apparatus, cutting is performed while supplying a cutting fluid to the cutting portion. The main purpose of the supply of the cutting fluid is to suppress the frictional heat generated in the workpiece and the cutting tool by cutting and to cool. In addition, when the cutting fluid is supplied, cutting scraps are removed and lubrication is performed.

  By the way, when the cutting fluid is supplied to the cutting portion, the cutting waste is mixed with the cutting fluid, and becomes sewage (contamination, hereinafter referred to as contamination) and is scattered around. The scattered contaminants may adhere to the lens surface that is the surface of the objective lens mounted on the microscope that constitutes the imaging apparatus that faces the workpiece. If the deposit adheres to the lens surface, problems such as erroneous detection of a region to be cut of the workpiece imaged through the objective lens and erroneous recognition of the state of the cutting groove occur. Therefore, a means for preventing contamination from adhering to the objective lens has been proposed (Patent Document 1).

JP 2002-11461 A

  The means for preventing contamination from adhering to the objective lens described in the above-mentioned patent document is such that the objective lens is covered with a sealing cover, and the opening below the sealing cover is closed with an opening / closing lid. When the imaging is not performed, the open / close lid is closed, and when the open / close lid is opened and the image is taken, the air sent into the hermetic cover is blown out from the lower opening to prevent contamination on the objective lens. It is supposed to prevent. However, with this adhesion prevention means, the objective lens is exposed to an atmosphere containing contaminants when imaging with the open / close lid open, and even if air is sent into the hermetic cover, the air blocking effect is sufficient. I couldn't say anything.

  The present invention has been made in view of the above circumstances, and its main technical problem is that it can effectively prevent contamination from adhering to the lens surface of the objective lens, and the lens surface is in a clean state. It is an object of the present invention to provide an imaging device that can be maintained at the same time.

The present invention is an imaging apparatus comprising: an objective lens having a lens surface facing an imaging object; and objective lens protection means for preventing adhesion of an adherent to the lens surface, wherein the objective lens protection means A gap forming member that has an opening at a position corresponding to a central portion of the lens surface of the objective lens and that is disposed opposite the lens surface to form a gap with the lens surface; The gas is introduced into the gap, and the gas flows along the lens surface of the objective lens and the opening of the gap forming member, and flows into the opening from the gap. possess the injection passage for injecting toward the gas to the imaging object, wherein the periphery of the opening of the gap forming member is formed with an annular groove, through the gas inlet portion is communicated to the annular groove and said that you are.

  According to the present invention, the gas is introduced from the gas introduction portion into the gap formed between the lens surface of the objective lens and the gap forming member, and the gas flows along the lens surface and then the gap forming member. It enters the injection flow path from the opening and injects toward the object to be imaged. Here, when contamination such as sewage is scattered from the imaging target toward the objective lens, the contamination is transferred to the injection flow path by the gas sprayed from the injection flow path toward the imaging target object. Intrusion is prevented. As a result, it is difficult for contamination to reach the lens surface of the objective lens, and adhesion of contamination to the lens surface is prevented. Further, even if the contamination adheres to the lens surface, the contamination can be quickly removed by the gas flowing along the lens surface.

In the present invention, from the viewpoint of preventing contamination from reaching the lens surface of the objective lens through the ejection flow path, the effect of preventing the adhesion of contamination is more sufficient. It is preferable that the area S (mm ² ) satisfies L / S ≧ 0.25.

  According to the present invention, it is possible to effectively prevent contamination from adhering to the lens surface of the objective lens, and it is possible to maintain the lens surface in a clean state.

It is a perspective view of a cutting device provided with an imaging device concerning one embodiment of the present invention. It is a perspective view of the cutting means and imaging device which the cutting device comprises. It is a front view (an imaging device is sectional drawing) of the cutting means and imaging device shown in FIG. It is a disassembled perspective view of the imaging device of one embodiment. It is (a) sectional side view of the imaging device of one Embodiment, (b) It is a principal part enlarged view. (A) is AA sectional drawing of Fig.5 (a), (b) is a principal part enlarged view. (A) is a perspective view which shows typically the cross section of the clearance gap concerning this invention, (b) is a perspective view which shows the cross section of an injection flow path typically.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a cutting apparatus 10 according to an embodiment. The apparatus 10 uses a disk-shaped semiconductor wafer (hereinafter abbreviated as “wafer”) 1 shown in FIG. 1 as a workpiece, and automatically controls the cutting operation by the cutting blade 65 to handle the wafer 1 in a number of devices. It is a dicing apparatus for dicing into (semiconductor chip).

(1) Wafer First, the wafer 1 that is a workpiece will be described. The wafer 1 has a thickness of, for example, about 100 to 700 μm, and a large number of rectangular devices 2 are formed on the surface by grid-like division lines. These devices 2 are formed with electronic circuits such as IC and LSI (not shown). Cutting (dicing) by the cutting device 10 includes groove processing in which a groove is formed by cutting from the surface to the middle of the thickness in addition to a full cut that completely cuts through the thickness of the wafer 1. When the grooves are formed, the wafer 1 is divided into a number of devices 2 by further cutting the remaining thickness of the grooves with another cutting blade in the subsequent process or by applying stress to cleave them. The

  The wafer 1 is supplied to the cutting device 10 in a state where it is integrally supported on the inner side of the annular frame 3 via the adhesive tape 4 in a concentric manner. The adhesive tape 4 has an adhesive surface on one side, and the frame 3 and the wafer 1 are attached to the adhesive surface. The frame 3 has rigidity made of a plate material such as metal, and the wafer 1 is transferred by supporting the frame 3.

(2) Cutting Device (2-1) Configuration of Cutting Device Next, the configuration of the cutting device 10 shown in FIG. 1 will be described. The cutting device 10 is a two-axis opposed type in which a pair of cutting blades 65 are arranged to face each other. 1 is a base, and a rectangular recess 12 whose longitudinal direction extends in the X-axis direction is formed at the center of the base 11. A disc-shaped chuck table (holding table) 20 is provided in the recess 12 so as to be movable in the X-axis direction. Further, a portal column 30 straddling the recess 12 is fixed on the rear side (X2 direction side) on the base 11 in FIG.

  The chuck table 20 is supported on the table base 25 so as to be rotatable about the Z-axis direction which is the vertical direction as a rotation axis, and is rotated clockwise or counterclockwise by a rotation driving mechanism (not shown) provided on the table base 25. To be rotated. The table base 25 is configured to reciprocate in the X-axis direction by a moving mechanism (not shown) disposed in the recess 12. As the table base 25 moves, the chuck table 20 can be reciprocated between the attaching / detaching position on the front side in the X-axis direction (X1 direction side) and the processing position on the back side (X2 direction side) in FIG. .

  The chuck table 20 is of a general well-known vacuum chuck type, and most of the peripheral portion of the horizontal upper surface is a circular suction surface 21 that sucks and holds the wafer 1. The diameter of the suction surface 21 is substantially the same as the diameter of the wafer 1, and the entire wafer 1 is placed concentrically on the suction surface 21 and held. The wafer 1 supported by the frame 3 as described above is placed on the suction surface 21 of the chuck table 20 in a vacuum operation state, and is sucked and held. Around the chuck table 20, a plurality of clamps 26 for detachably holding the frame 3 are disposed. These clamps 26 are attached to the table base 25.

  The periphery of the chuck table 20 is covered with a rectangular plate cover 27. The plate cover 27 is supported by the table base 25 and moves in the X-axis direction together with the chuck table 20. An elastic bellows-like cover 28 that covers the recess 12 is attached to both ends of the plate cover 27 in the X-axis direction. The recess 12 is always covered with the plate cover 27 and the cover 28 even when the chuck table 20 moves in the X-axis direction. Thereby, the cutting fluid and cutting waste used at the time of cutting are prevented from falling on the moving mechanism that moves the table base 25 in the X-axis direction.

  The portal column 30 has a pair of leg portions 31 erected side by side in the Y-axis direction on both sides of the recess 12, and a beam portion 32 laid horizontally between the upper ends of the leg portions 31. doing. A pair of upper and lower Y-axis guides 33 extending in the Y-axis direction are provided on the front side (X1 direction side) of the beam portion 32 in FIG. 1, and the first Y-axis slider 41 and the Y-axis guide 33 are connected to the Y-axis guide 33. A second Y-axis slider 42 is slidably attached. The first Y-axis slider 41 is reciprocated along the Y-axis guide 33 by a first Y-axis ball screw feed mechanism 412 operated by a first Y-axis feed motor (not shown). The second Y-axis slider 42 is reciprocated along the Y-axis guide 33 by a second Y-axis ball screw feed mechanism 422 operated by a second Y-axis feed motor 421.

  The first Y-axis slider 41 and the second Y-axis slider 42 are each provided with a pair of Z-axis guides 34 extending in the Z-axis direction. The first Y-axis slider 41 includes a first Z-axis slider 51. The second Z-axis slider 52 is slidably attached to the Z-axis guide 34 of the second Y-axis slider 42. The first Z-axis slider 51 is moved up and down along the Z-axis guide 34 by a first Z-axis ball screw feed mechanism (not shown) operated by a first Z-axis feed motor 511. Further, the second Z-axis slider 52 is moved up and down along the Z-axis guide 34 by a second Z-axis ball screw feed mechanism (not shown) operated by the second Z-axis feed motor 512.

  The first cutting means 61 is fixed to the lower end of the first Z-axis slider 51 via a first bracket 611, and the second cutting is applied to the lower end of the second Z-axis slider 52 via a second bracket 621. Means 62 are fixed. Each of the cutting means 61 and 62 has the same configuration, and a cylindrical rotating shaft that is rotated at high speed by a servo motor or the like is accommodated in a rectangular parallelepiped spindle housing 63, and the rotating shaft that protrudes from the tip opening of the spindle housing 63. The disc-shaped cutting blade 65 is concentrically attached to the tip of the blade. Below the cutting means 61 and 62 is the processing position.

  In the cutting means 61 and 62, the spindle housing 63 of the first bracket 611 and the second bracket 621 is in a state in which the rotation axis is parallel to the Y-axis direction and coaxial with each other, and the tips to which the cutting blades 65 are attached face each other. Each is fixed to the lower end. The cutting means 61 and 62 are moved in the Y-axis direction integrally with the Y-axis sliders 41 and 42, respectively, and approach or separate from each other in the Y-axis direction. A blade cover 70 is attached to the tip of the spindle housing 63 to suppress scattering of the cutting fluid splashed up by the rotating cutting blade 65 to the periphery.

  The cutting blade 65 cuts and cuts the wafer 1 held on the chuck table 20. In the present apparatus 10, the rotating shaft that supports the cutting blade 65 extends in the Y-axis direction. Therefore, the machining feed direction in which the cutting blade 65 cuts into the wafer 1 and advances the cutting is the X-axis direction. On the other hand, the index feed direction for moving the cutting blade 65 in the axial direction is the Y-axis direction. Therefore, the machining feed of the cutting blade 65 is performed by moving the chuck table 20 in the X-axis direction and moving the wafer 1 in the X-axis direction relative to the cutting blade 65. Further, the indexing and feeding is performed by moving the Y-axis sliders 41 and 42 in the Y-axis direction.

  As shown in FIG. 2 (the cutting means in FIG. 2 shows the first cutting means 61), the cutting blade 65 is mainly covered with the blade cover 70 on the upper periphery, and is exposed from the blade cover 70. The wafer 1 is cut with a cutting edge at the lower end. For example, the cutting blade 65 cuts into the wafer 1 and cuts it while rotating at high speed in the direction of arrow A in FIG. The blade cover 70 has a base portion 71 that is fixed to the tip of the spindle housing 63. The base portion 71 includes a front cover 72 that covers the front in the rotational direction of the cutting blade 65, and an upper portion of the cutting blade 65. And a movable cover 73 covering the rear. The movable cover 73 has a triangular side cover 731 that covers the rear part of the exposed side surface of the cutting blade 65. The movable cover 73 is moved in the X2 direction by the cylinder device 74 from the state of cutting in FIG. 2 so that the cutting blade 65 can be attached and detached.

  A plurality of outer peripheral nozzles 81 (only one is visible in FIG. 2) arranged in the Y-axis direction are provided at the lower end of the surface of the front cover 72 facing the cutting blade 65. The liquid is ejected toward the cutting blade 65. In addition, two parallel side nozzles 82 whose front end portions extend in the X-axis direction are attached to the movable cover 73 so as to be disposed on both sides of the cutting blade 65. A plurality of slits 821 are formed in the side nozzles 82, and the cutting fluid is ejected from the slits 821 toward the cutting blade 65. Connection pipes 91 and 92 to which cutting fluid supply pipes are connected are respectively attached to the front cover 72 and the movable cover 73.

  As shown in FIG. 2, the imaging device 100 according to an embodiment is fixed via a bracket 64 at a location on the front surface (X1 direction side surface) of the spindle housing 63 and close to the blade cover 70. When the imaging apparatus 100 images the surface of the wafer 1 before cutting and detects a region to be cut by the cutting blade 65, or confirms the state of a groove formed on the surface side of the wafer 1 by cutting. It has an optical system such as a microscope and a CCD camera inside. Detection of the cutting area of the wafer 1 and confirmation of the state of the grooves formed by cutting are performed based on the image of the wafer surface imaged by the imaging device 100. The imaging apparatus 100 will be described in detail later.

(2-2) Outline of Operation of Cutting Apparatus The above is the overall configuration of the cutting apparatus 10 according to an embodiment. Next, an outline of an operation example in which the wafer 1 is diced into a large number of devices 2 by the cutting apparatus 10 will be described. To do.

  The wafer 1 is sucked and held on the chuck table 20 while being supported by the frame 3 via the adhesive tape 4, and the chuck table 20 moves in the X2 direction in FIG. It is conveyed to a lower processing position. In this processing position, the surface of the wafer 1 is imaged by the imaging device 100 before cutting, and a line to be divided between the devices 2 is detected. Next, based on the imaging data of the imaging device 100, among a plurality of intersecting planned lines that intersect, first, the side extending in one direction is first cut, and then all the planned dividing lines on the side extending in the other direction are cut. The wafer 1 is diced into a number of devices 2. The division lines to be cut are determined in parallel with the X-axis direction by rotating the chuck table 20 and rotating the wafer 1.

  In the cutting process, the cutting blade 65 whose lower edge is set at a predetermined cutting height (position in the Z-axis direction) while moving the chuck table 20 in the X2 direction is rotated in the X2 direction with respect to the division line. This is done by performing a process feed for cutting from the end on the side toward the end on the X1 direction side. When one machining feed is completed, the cutting blade 65 is retracted upward, the chuck table 20 is moved in the X1 direction, the cutting blade 65 is returned to the starting point of the machining feed, and the cutting means 61 and 62 are moved in the Y-axis direction. Then, the indexing feed for aligning the cutting edge of the cutting blade 65 with the next division line is performed, and then the cutting blade 65 is processed and fed to the next division line. By performing the above operation, cutting is applied to all the division lines extending in the X-axis direction.

  In addition, the cutting process with respect to the wafer 1 has forms, such as a full cut and a groove process, as mentioned above. FIG. 3 shows a full cut in which the cutting edge of the cutting blade 65 completely cuts through the thickness of the wafer 1. In this embodiment, the tip of the cutting blade 65 reaches the middle of the thickness of the adhesive tape 4. Yes.

(3) Imaging Device (3-1) Configuration of Imaging Device Next, the imaging device 100 will be described. As shown in FIGS. 4 and 5, the imaging apparatus 100 includes a microscope 110 and a disk-shaped cover member (objective lens protection means) 120 that is detachably attached to the lower end of the microscope 110. Yes.

  As shown in FIG. 5, the microscope 110 includes a cylindrical casing 111 and an objective lens 113 disposed in an opening 112 a on one end side of the casing 111. The opening 112 a is formed in a small-diameter portion 112 formed so as to protrude from the center on one end side of the casing 111, and the objective lens 113 is fixed to the inner peripheral surface of the small-diameter portion 112. A lens surface 113a that is the lower surface of the objective lens 113 is exposed downward. A CCD camera 115 that captures an image passing through the objective lens 113 is incorporated in the casing 111 of the microscope 110.

  A circular recess 121 is formed at the center of the upper surface side of the cover member 120, and the small diameter portion 112 of the casing 111 of the microscope 110 is detachably fitted in the recess 121 (downward in FIG. 4). The arrow indicates the fitting direction of the small diameter portion 112 to the recess 121). In this way, the objective lens 113 is disposed inside the cover member 120 with the microscope 110 mounted on the cover member 120.

  As shown in FIG. 5, an annular convex portion (gap forming member) 122 is formed at the center of the bottom surface of the recess 121 of the cover member 120. The annular convex portion 122 faces the lens surface 113 a of the objective lens 113, and the upper opening portion 122 a opens at a position corresponding to the central portion of the objective lens 113. A gap 123 is formed between the upper edge of the annular convex portion 122 and the lens surface 113a of the objective lens 113.

  An annular groove 124 is formed around the annular convex portion 122, and an air introduction flow path (gas introduction portion) 125 that communicates with the annular groove 124 from the outside of the cover member 120 is formed in the cover member 120. . The air introduction channel 125 extends from the annular groove 124 in the radial direction of the cover member 120 and then bends at a right angle upward and opens to an air introduction port 125 a formed on the upper surface of the cover member 120. A compressed air supply hose 130 shown in FIG. 2 is connected to the air inlet 125a. In addition, an injection passage 126 penetrating from the upper opening 122a of the annular convex portion 122 to the injection port 126a that opens to the bottom surface is formed at the center of the cover member 120.

(3-2) Operation of Imaging Device and Effects Accompanying The Imaging Device 100 is brought close to the wafer (imaging object) 1 held on the chuck table 20 from above, and the surface of the wafer 1 through the ejection channel 126. The surface of the wafer 1 is imaged by the CCD camera 115 in a state where the lens surface 113a faces the surface. That is, the CCD camera 115 captures an image of a part of the surface of the wafer 1 that can be seen from the ejection port 126a of the ejection channel 126. When the wafer 1 is cut, compressed air is sent into the cover member 120 from the supply hose 130.

  The compressed air fed into the cover member 120 enters the annular groove 124 around the annular convex portion 122 from the air introduction port 125a through the air introduction passage 125 as shown by the broken line arrows in FIGS. . Next, the compressed air ascends in the annular groove 124, passes through the gap 123 between the upper edge of the annular convex portion 122 and the lens surface 113 a of the objective lens 113, enters the injection flow path 126 from the upper opening 122 a, and descends. Go. The compressed air flows along the lens surface 113a while the compressed air enters the ejection flow path 126 from the gap 123 through the upper opening 122a. Then, the compressed air descends through the ejection flow path 126 and is discharged while being ejected from the ejection port 126a toward the lower wafer 1.

  By the way, during cutting of the wafer 1, the cutting fluid is ejected from the outer peripheral nozzle 81 and the side nozzle 82 provided on the blade cover 70 to the cutting blade 65 and the wafer 1, and the cutting blade 65 cuts into the wafer 1. Cutting fluid is supplied to the machining point. The cutting fluid is splashed from the processing point by the rotating cutting blade 65 and scattered around. The used cutting fluid scattered by the rotating cutting blade 65 is in a contamination (sewage) state in which cutting waste generated by cutting is mixed.

  As shown in FIG. 3, when the wafer 1 is being cut by the cutting blade 65, the lower surface of the cover member 120 of the imaging device 100 is close to the wafer 1, and contamination (denoted by C in FIG. 3). May be scattered around the imaging apparatus 100 in some cases. However, in the imaging apparatus 100 according to the present embodiment, since the lens surface 113a of the objective lens 113 is covered with the cover member 120, there is no problem that scattered contaminants directly contact and adhere to the lens surface 113a.

  The space between the imaging device 100 where the contamination is scattered and the wafer 1 and the lens surface 113a of the objective lens 113 communicate with each other through the ejection flow path 126, but descend through the ejection flow path 126. Contamination is prevented from entering the injection flow path 126 by the compressed air that is injected from the injection port 126a (indicated by the arrow coming out of the injection port 126a in FIG. 3). For this reason, the contamination hardly reaches the lens surface 113a, and the adhesion of the contamination to the lens surface 113a is prevented. Even if contamination may adhere to the lens surface 113a, since the compressed air flows along the lens surface 113a as described above, the compressed air that has flowed adheres to the lens surface 113a. Contaminated contamination is removed.

  As a result, contamination is effectively prevented from adhering to the lens surface 113a of the objective lens 113, the lens surface 113a is always kept clean, and the wafer 1 is clearly imaged and erroneous detection and recognition are prevented. Is prevented.

Note that when the ejection flow path 126 has a distance as long as possible and a cross-sectional area as narrow as possible within the range in which the wafer 1 can be imaged by the CCD camera 115, the contamination is the lens surface 113a of the objective lens 113. It is easy to obtain the effect of preventing adhesion. Here, considering that the wafer 1 can be imaged, if the length of the ejection flow path 126 is L (mm) and the cross-sectional area is S (mm ² ), L / S ≧ 0.25. Satisfaction is practical, and L / S is preferably 0.5 or more, more preferably 1.0 or more. Specifically, for example, the length L is set to 19.5 mm and the inner diameter (φ) is set to 5 mm (cross-sectional area S is 19.6 mm ² ). In this case, L / S is close to 1.

Further, the distance of the gap 123 between the upper edge of the annular convex portion 122 and the lens surface 113a of the objective lens 113 is the cross-sectional area of the gap 123 corresponding to the inner peripheral edge of the ejection flow path 126. Is substantially the same as the cross-sectional area of the gas flow path, since there is almost no change in the area of the flow path from the gap 123 to the injection flow path 126, and compressed air flows smoothly. That is, when the cross section of the injection flow passage 126 is circular, the cross sectional area of the gap 123 is a broken line portion indicated by an arrow S2 in FIG. 5B, which is as shown in FIG. It is cylindrical. On the other hand, the cross-sectional area of the injection flow path 126 is a broken line portion indicated by an arrow S1 in FIG. 5B, and this is a disk shape as shown in FIG. 7B. Here, assuming that the radius of the ejection flow path 126 is r and the distance of the gap 123 is h, S1 = πr ² and S2 = 2πr × h, and in order to set S1 = S2, h = r / 2 holds. That is, it can be said that the gap 123 has an optimum distance of about ½ of the radius of the ejection flow path 126.

For example, when the diameter of the injection channel 126 having a circular cross section is φ5 mm (radius is 2.5 mm, cross-sectional area is 19.6 mm ² ) as described above, the gap 123 is optimally 1.25 mm. Even if S1 and S2 cannot be made equal by design, a smooth flow of compressed air can be obtained as long as about ± 30% of the optimum value.

  In addition to setting the gap 123, the compressed air can flow smoothly through the gap 123 at an appropriate pressure by setting the flow rate of the compressed air flowing through the gap 123 to about 20 to 50 L / min.

  In imaging the surface of the wafer 1, it is generally performed to remove moisture and the like by blowing away air and clean the imaging target surface. However, according to the imaging apparatus 100 of the present embodiment, the ejection port 126 a is used. Compressed air sprayed from the surface can be sprayed onto the surface of the wafer 1 for cleaning. That is, it can also serve as a function of cleaning the surface of the wafer 1 at the time of imaging, so that it is possible to suppress the complexity of the apparatus and the increase in the number of parts. In addition, in order to blow away moisture on the surface of the wafer 1 and clean it, when the flow rate of the compressed air flowing through the gap 123 is about 20 to 50 L / min, the injection flow path 126 has a circular cross section, for example, A maximum of φ2 mm is effective.

1 ... Semiconductor wafer (object to be imaged)
DESCRIPTION OF SYMBOLS 10 ... Cutting device 100 ... Imaging device 113a ... Lens surface 113 ... Objective lens 120 ... Cover member (objective lens protection means)
122a ... Upper opening (opening)
123 ... gap 122 ... annular convex part (gap forming member)
125 ... Air introduction channel (gas introduction part)
126 ... injection flow path

Claims (2)

An objective lens having a lens surface facing the imaging object;
An objective lens protection means for preventing adhesion of deposits to the lens surface, and an imaging device comprising:
The objective lens protection means includes
A gap forming member that has an opening at a position corresponding to a central portion of the lens surface of the objective lens, and that forms a gap with the lens surface by being disposed facing the lens surface;
A gas introduction part for introducing a gas into the gap and causing the gas to flow along the lens surface of the objective lens;
An ejection flow path that communicates with the opening of the gap forming member and injects the gas flowing into the opening from the gap toward the imaging target;
I have a,
An imaging apparatus , wherein an annular groove is formed around the opening of the gap forming member, and the gas introducing part communicates with the annular groove . The imaging apparatus according to claim 1, wherein a length L (mm) and a cross-sectional area S (mm ² ) of the ejection flow path satisfy L / S ≧ 0.25.

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