Reticle inspection apparatus and projection exposure apparatus

Abstract

The invention provides a reticle inspection apparatus and a projection exposure apparatus. The purpose of the present invention is to suppress or prevent unable inspection of a range when inspecting a foreign matter on a rectangular reticle. A reticle inspection device is provided with: an illumination unit that irradiates a rectangular reticle with light; an imaging unit that captures an image of the reticle; and an inspection unit that detects the foreign matter by inspecting the captured image, in which the illumination unit takes the entire surface of the inspection surface of the reticle as an irradiation range of light, and the imaging unit takes the entire surface of the inspection surface as a field of view.

Description

Technical Field

[0001] The present invention relates to an intermediate mask inspection device and a projection exposure device having the intermediate mask inspection device. Background Art

[0002] The projection exposure device projects the pattern of the reticle onto the substrate using ultraviolet rays. However, if there is foreign matter on the reticle, the image of the foreign matter will also be transferred to the substrate, causing defects such as circuit disconnection. Therefore, it is usually necessary to perform an optical inspection to check whether there is foreign matter such as dirt on the reticle before the exposure process. The reticle inspection is automated and is performed using a camera and image processing technology.

[0003] In order to shorten the inspection time of the intermediate mask, it is preferred to photograph the entire surface of the intermediate mask and inspect it at once, unlike the method of scanning the intermediate mask with a point light or a line light. For example, Patent Document 1 discloses an embodiment in which both sides of a mask (intermediate mask) substrate can be inspected at the same time. Patent Document 1 describes the following: TV cameras 23 and 24 respectively photograph the front and back sides of the mask M supported only by the peripheral portion, and TV receivers 31 and 32 display the photographed images, thereby enabling the front and back sides to be observed at the same time.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 58-154229

[0005] In order to photograph the entire surface of the intermediate mask, when the entire surface of the intermediate mask is illuminated, scattered light is generated at the edge of the intermediate mask. The scattered light at the edge of the intermediate mask is stronger than the scattered light caused by foreign matter, so when the scattered light enters the camera, a halo is generated along the edge of the intermediate mask. Due to the halo, there is a problem that foreign matter inspection near the edge of the intermediate mask cannot be performed. In order to avoid the influence of scattered light, it is considered to set a light shielding component in front of the TV camera, but this method requires strict alignment between the edge of the intermediate mask and the TV camera. In addition, since the light shielding component cannot be set at the focus position of the TV camera, the focus of the light shielding part is not aligned, resulting in a problem that inspection near the edge cannot be performed. Summary of the invention

[0006] Therefore, an object of the present invention is to provide a reticle inspection apparatus and a projection exposure apparatus having the reticle inspection apparatus, which can illuminate the entire surface of a reticle having an edge and prevent the vicinity of the edge of the reticle from being unable to be inspected.

[0007] The present invention is an intermediate mask inspection device, wherein an illumination unit irradiates light onto a rectangular intermediate mask, a photographing unit photographs the intermediate mask, and an inspection unit detects foreign matter by inspecting the photographed image, wherein the illumination unit uses the entire inspection surface of the intermediate mask as the light irradiation range, the photographing unit uses the entire inspection surface as the field of view range, and the inspection unit inspects the image of the entire inspection surface.

[0008] Furthermore, the present invention is a projection exposure device, which comprises: an intermediate mask stage, on which a rectangular intermediate mask is placed; a projection unit, which projects the exposure light that has passed through the intermediate mask onto a substrate; and an intermediate mask inspection unit, which inspects the intermediate mask. The intermediate mask inspection unit is the intermediate mask inspection device described in the aforementioned technical solution. After the intermediate mask inspection unit performs inspection, the intermediate mask is placed on the intermediate mask stage to start the exposure process.

[0009] According to at least one embodiment, the entire surface of the intermediate mask can be inspected at once, and the vicinity of the intermediate mask edge portion can be prevented from being unable to be inspected due to halo. In addition, the effects described here are not necessarily limited, and can also be any effect described in this specification or an effect that is heterogeneous with them. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A and Figure 1 B is a top view and a side view schematically showing the overall structure of the exposure device.

[0011] Figure 2 is a cross-sectional view showing an example of a reticle.

[0012] Figure 3 It is a perspective view of one embodiment of a reticle inspection apparatus.

[0013] Figure 4 This is a perspective view of a reticle and a light source holding unit provided in a reticle inspection device.

[0014] Figure 5 A and Figure 5 B is a schematic diagram for explaining the optical positional relationship between a light source and an intermediate mask in one embodiment.

[0015] Figure 6 This is a flowchart for explaining the operation of the exposure device.

[0016] Figure 7 This is a flowchart for explaining the operation of the reticle inspection apparatus.

[0017] Description of symbols

[0018] R: intermediate mask; PG: glass surface; PE: dust-proof film; 11: light source and illumination optical system; 12: intermediate mask stage; 14: substrate stage; 21: intermediate mask inspection device; 22: transport robot; 23: intermediate mask box; R: intermediate mask; 43: dust-proof film surface shooting device; 44: glass surface shooting device; 45: intermediate mask and light source holding part; 48: light source. DETAILED DESCRIPTION

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are preferred specific examples of the present invention, and the content of the present invention is not limited to these embodiments.

[0020] Figure 1 A and Figure 1 B is a schematic top view and a side view showing the entire exposure device, Figure 1 The A is from Figure 1 The present invention is applicable to the top view of the AA line of B. Figure 1 A and Figure 1 The intermediate mask inspection device 21 in B.

[0021] The exposure device body includes: a light source and an illumination optical system 11, which irradiates (illuminates) the exposure light emitted from the light source to the intermediate mask; an intermediate mask stage 12, which supports the intermediate mask and positions the intermediate mask; a projection optical system 13, which projects the light transmitted through the intermediate mask onto the substrate; and a substrate stage 14, which places the substrate and positions the substrate. The substrate is a semiconductor silicon wafer, a printed wiring board, etc. These components are arranged on a stand 15 with the aid of a frame (not shown).

[0022] A transfer robot 22 for transferring the reticle and the substrate is provided adjacent to the exposure device body. A reticle inspection device 21, a reticle box 23, and a substrate box 24 are provided around the transfer robot 22. The external package of the exposure device is provided to contain all the above components. The external package is an air-conditioned chamber provided with a temperature and humidity adjustment unit (not shown).

[0023] Figure 2 An example of a reticle R is shown. The reticle R has a pattern surface PT having a shape in which a metal reflective film such as chromium is formed on a rectangular plate-shaped quartz glass substrate 31 and a light-transmitting portion is provided on the reflective film to allow light to pass through the pattern to be exposed. The pattern surface PT coincides with the focus of the projection lens.

[0024] In order to prevent foreign matter from adhering to the pattern surface PT, a dustproof film PE is provided via a spacer 32. The dustproof film PE is a thin and transparent film. The dustproof film PE is provided at a distance of several mm from the pattern surface PT. Even if there is foreign matter at a position away from the pattern surface PT, it will not be focused on the substrate and will not become a defect. However, if a relatively large foreign matter is attached to the dustproof film PE, it will affect the exposure, so it is necessary to check not only the foreign matter on the glass surface PG of the quartz glass 31 but also the foreign matter on the dustproof film PE.

[0025] The light source and illumination optical system 11 of the exposure apparatus body includes a light source (LED light source, mercury lamp, etc.) and a light quantity equalizing unit such as a fly-eye lens for equalizing the light from the light source. The light from the light source and illumination optical system 11 evenly illuminates the reticle.

[0026] The reticle stage 12 has a reticle stage for placing the reticle and a moving mechanism for moving the reticle stage in the xyθ direction. The reticle stage has an opening so that light passing through the reticle passes through the projection optical system. The projection optical system 13 is a projection lens that projects light passing through the reticle onto the substrate surface.

[0027] The substrate stage 14 includes a substrate stage on which a substrate is placed and a moving mechanism for moving the substrate stage in the xyθ direction. The substrate stage 14 may include lift pins and the like for transferring the substrate to and from a transport robot.

[0028] The reticle cassette 23 is a cassette for storing a plurality of reticle masks provided with dust-proof films. The exposure apparatus selects and uses one reticle that meets the exposure conditions from among the plurality of reticle masks stored in accordance with the process (production process information).

[0029] The substrate box 24 is a box for storing a plurality of substrates before exposure and substrates after exposure. A plurality of substrate boxes 24 may be provided, and substrates before exposure and substrates after exposure may be stored in different boxes. The substrate box 24 is transported to the exposure device by an AVG (Automatic Guided Vehicle) or the like. In addition, it is also possible not to provide a substrate box, but to successively transport substrates before exposure from an upstream device to the exposure device by a conveyor or the like, and successively deliver the exposed substrates to a downstream device.

[0030] The transfer robot 22 includes a substrate robot that transfers a substrate between the substrate cassette 24 and the substrate stage 14, and a reticle robot that transfers a reticle between the reticle cassette 23, the reticle inspection device 21, and the reticle stage 12. As the transfer robot 22, a known SCARA robot or the like can be used.

[0031] Reference Figure 3 An example of reticle inspection apparatus 21 will be described. This reticle inspection apparatus 21 has upper frame 42 mounted on lower frame 41. Lower frame 41 and upper frame 42 are box-shaped structures obtained by connecting corner column members corresponding to the respective sides, and the respective faces of the box-shaped structure are open.

[0032] A dust-proof film surface photographing device 43 is installed on the lower frame 41, and a glass surface photographing device 44 is installed on the upper frame 42. The dust-proof film surface photographing device 43 and the glass surface photographing device 44 each include: a photographing unit, such as a camera; and an inspection unit 49, which processes the photographing signal of the camera to inspect whether there is a foreign object. The camera is arranged on a central axis that is perpendicular to the inspection surface and passes through the center of the intermediate mask. In addition, the camera takes the entire surface of the inspection surface as a field of view.

[0033] A middle mask and a light source holding part 45 are provided at the upper part of the lower frame 41 close to the upper frame 42. Figure 4 As shown, the reticle and light source holding unit 45 has an opening for the transfer robot to place the rectangular reticle R, a support member 46 provided below the opening to support the peripheral portion of the reticle R from below without contacting the dustproof film PE, and a light source support unit 47 disposed outside the opening. For example, the transfer robot has a hand that can place and transfer the reticle in order to transfer the reticle.

[0034] On the light source support 47, an illumination unit composed of a total of eight light sources 48 is mounted on the front and back of the reticle R. The positions of the light sources 48 on the extension lines of the diagonal lines of the reticle R are arranged close to the corners. The light sources 48 irradiate diffuse light from the four corners toward the center of the reticle, and the reticle R is set in the opening by the hand of the transfer robot. The light sources 48 are LED light sources that generate wavelengths that are sensitive to the camera, such as orange light of 600nm, green light of 550nm, etc.

[0035] The illumination unit composed of the light source 48 irradiates illumination light from the vicinity of the corners of the reticle R toward the center, thereby illuminating the entire surface of the reticle R. A glass surface (at the Figure 4 The four light sources 48 (the upper surface in the middle) and the dust-proof film surface (in the middle) of the intermediate mask R are illuminated. Figure 4 The four light sources 48 disposed near the corners of the intermediate mask R can form uniform illumination light.

[0036] Figure 5 A and Figure 5 B is a schematic diagram showing the optical positional relationship between the light source 48 and the intermediate mask R.

[0037] Figure 5 A shows the optical position relationship of one embodiment of the present invention, Figure 5 B illustrates the situation where scattered light is generated at the edge of the intermediate mask in the conventional intermediate mask inspection apparatus. In addition, one light source 48 of the four light sources irradiating the glass surface PG is shown, and the illustration of the light source 48 irradiating the dustproof film PE is omitted.

[0038] When the glass surface PG is set as the xy plane and the plane perpendicular to the xy plane is set as the xz plane, the diffused light generated by the light source 48 is incident obliquely to the x direction at a small incident angle. The incident angle is an angle that causes total reflection (for example, 5°). Therefore, images that are not necessary for inspection, such as the image of the pattern surface of the intermediate mask R, will not be captured. Foreign matter attached to the glass surface PG causes scattered light, so it becomes a high-brightness image in the captured image and can be detected. In addition, the optical relationship between the light source 48 and the dustproof film PE is the same as the optical relationship between the light source 48 and the glass surface PG.

[0039] When the inspection surface (glass surface PG and dustproof film PE) of the intermediate mask R is illuminated at a shallow angle as described above, and the camera is set at a position separated in the vertical direction from the center of the dustproof film surface, if there is no foreign matter, the illumination light will not enter the camera field of view, and the screen will be black. If there is a foreign matter, part of the diffusely reflected light caused by the foreign matter will reach the camera, and a white reflected image of the foreign matter will appear on the black background. The inspection unit 49 processes the camera image to determine the presence and position of the foreign matter, and notifies when a foreign matter is detected.

[0040] If the reticle R is illuminated at a shallow incident angle using a linear LED light source parallel to one side of the reticle R, as opposed to one embodiment of the present invention, a halo is generated near the edge of the side at a position far from the incident side of the reticle in the image captured by the camera. This causes the following problem: in the region where the halo is generated, a foreign matter cannot be inspected, and the presence or absence of foreign matter cannot be inspected. One embodiment of the present invention can suppress this halo.

[0041] like Figure 5 As shown in FIG. 1B , when the optical axis of the light source 48 is approximately perpendicular to the side surface of the incident side of the reticle R in the xy plane, the light enters the interior of the reticle from the side surface of the reticle R, and reaches the side surface of the side opposite to the incident surface by reflection from the inner surface. A portion of the illumination light directly passes through the side surface, and the other portion is reflected on the inner surface of the side surface. The reflected light is emitted from the chamfered portion, and is thus observed as scattered light at the edge of the reticle. Halo is generated due to this scattered light.

[0042] In one embodiment of the present invention, in the xy plane, the optical axis of the light source 48 is inclined relative to the side surface of the reticle R. That is, since the illumination light is incident from the corner of the reticle R, most of the light is reflected from the side surface of the reticle R, and the light propagating inside the reticle R is reduced. As a result, scattered light is less likely to be generated at the edge of the reticle R, halation is suppressed, and it is possible to prevent an uninspectable area from being obtained near the edge of the reticle.

[0043] Reference Figure 6 The flowchart of the above Figure 1 The operation of the exposure device shown will be described.

[0044] Step S1: Read in the process and select the intermediate mask.

[0045] Step S2 : The transport robot 22 takes out the reticle from the reticle cassette 23 and sets the reticle in the reticle inspection device 21 .

[0046] Step S3: The reticle inspection device 21 inspects the glass surface and the dust-proof film surface of the reticle. If foreign matter is detected by the inspection, the operator is notified and the process is interrupted.

[0047] Step S4 : When no foreign matter is detected in the reticle, the transfer robot 22 takes the reticle out of the reticle inspection device 21 and sets it on the reticle stage 12 .

[0048] Step S5 : the transfer robot 22 takes out the substrate from the substrate cassette 24 and places it on the substrate stage 14 .

[0049] Step S6: The exposure device body exposes the substrate.

[0050] Step S7 : the transport robot 22 removes the substrate from the substrate stage 14 and stores the substrate in the substrate box 24 .

[0051] Step S8: Determine whether the batch is finished. If the batch is not finished, the process returns to step S5 (mounting the substrate on the substrate stage 14).

[0052] Step S9 : If it is determined in step S8 that the lot is finished, the transfer robot 22 removes the reticle from the reticle stage 12 and stores it in the reticle cassette 23 , and the process ends.

[0053] The above-mentioned processing of step S1 to step S4 is the processing related to the intermediate mask inspection device 21. Figure 7 An example of the processing of the intermediate mask inspection device 21 will be described with reference to the flowchart of FIG.

[0054] Step S11: The hand of the transfer robot inserts the reticle into the reticle and light source holding unit 45 of the reticle inspection device 21 (at Figure 7 In the side opening above the intermediate mask support portion).

[0055] Step S12: The hand of the transfer robot 22 is lowered, and the reticle is placed on the reticle support portion.

[0056] Step S13: The hand of the transfer robot 22 withdraws from the reticle supporting portion.

[0057] The processing of steps S11, S12 and S13 is the same as Figure 6 The processing corresponding to step S2 (setting the intermediate mask in the intermediate mask inspection device) in FIG.

[0058] Step S14: The reticle illumination light source 48 of the reticle inspection device 21 is turned on.

[0059] Step S15: The camera photographs the glass surface and the dust-proof film surface.

[0060] Step S16: The light source 48 (reticle illumination) of the reticle inspection device 21 is turned off.

[0061] Step S17: The inspection unit 49 acquires the image captured by the camera.

[0062] Step S18: The inspection unit 49 performs image processing to obtain information on the presence or absence of foreign matter, and obtains information on the location of the foreign matter if there is foreign matter.

[0063] Step S19: When there is foreign matter, the inspection unit 49 notifies the operator.

[0064] Step S20: The hand of the transfer robot 22 moves forward and stops at a position below the reticle.

[0065] Step S21: The hand of the transfer robot 22 rises and receives the reticle from the reticle support portion (places the reticle on the hand).

[0066] Step S22 : The transfer robot 22 discharges the reticle from the reticle inspection device 21 and transfers it to the reticle stage 12 .

[0067] The processing of step S22 is Figure 6 The process corresponds to step S4 (taking out the reticle from the reticle inspection device 21 and setting the reticle on the reticle stage 12) in FIG.

[0068] As described above, as a pre-stage of the exposure process, the exposure device inspects the reticle through the reticle inspection device 21, and directly places the inspected reticle on the reticle stage 12. Then, the substrate is placed on the substrate stage 14, and the exposure operation of the substrate is repeated with a determined number of substrates (for example, 1 batch). After the exposure process is completed, the reticle is removed from the reticle stage 12 and stored in the reticle box 23.

[0069] In the above, an embodiment of the present technology is specifically described, but the present invention is not limited to the above embodiment, and various modifications can be made based on the technical concept of the present invention. For example, the present invention can also be applied to the inspection of an intermediate mask without a dustproof film. In addition, the present invention can also be applied to a laser processing device. In addition, the structures, methods, processes, shapes, materials, and numerical values ​​listed in the above embodiments are only examples, and different structures, methods, processes, shapes, materials, and numerical values ​​can be used as needed.

Claims

1. A middle mask inspection device, comprising: an illumination unit that irradiates light toward the rectangular reticle; an imaging unit that images the intermediate mask; and An inspection unit detects foreign matter by inspecting the captured image, in, The illumination unit uses the entire inspection surface of the intermediate mask as the irradiation range of light. The imaging unit has the entire surface of the inspection surface as a field of view.

2. The intermediate mask inspection apparatus according to claim 1, wherein: The lighting unit and the imaging unit are in a positional relationship such that when the inspection unit inspects the image of the entire inspection surface, a foreign matter uninspectable range due to scattered light generated at an edge portion of the reticle is not generated.

3. The intermediate mask inspection apparatus according to claim 1, wherein: The illumination unit includes a light source, which is disposed near a corner of the reticle and irradiates diffused light toward a center of the reticle.

4. The intermediate mask inspection apparatus according to claim 3, wherein: The light sources of the illumination unit are provided near all corners of the reticle to illuminate the entire inspection surface from four directions.

5. The intermediate mask inspection apparatus according to claim 1, wherein: The imaging unit is arranged on a central axis that is perpendicular to the inspection surface and passes through the center of the reticle.

6. The intermediate mask inspection apparatus according to claim 1, wherein: The other illumination unit irradiates an illumination light onto a surface of the reticle that faces the inspection surface, the other imaging unit images the opposing surface, and the inspection unit inspects the imaged image.

7. The intermediate mask inspection apparatus according to claim 6, wherein: A dust-proof film is provided separately from the opposing surface, The other illumination unit irradiates illumination light to the dust-proof film, the other imaging unit images the dust-proof film, and the inspection unit inspects the imaged image.

8. A projection exposure apparatus, comprising: A reticle stage on which a rectangular reticle is placed; a projection unit that projects the exposure light that has passed through the intermediate mask onto the substrate; and A reticle inspection unit that inspects the reticle, The intermediate mask inspection unit is the intermediate mask inspection device according to any one of claims 1 to 7, After the reticle inspection unit performs the inspection, the reticle is placed on the reticle stage and an exposure process is started.

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