Hereinafter, an exposing apparatus which employs one embodiment of the method and apparatus for measuring a drawing position of the present invention will be described in detail with reference to the drawings.
As shown in
In the exposing apparatus 10, the exposure head unit 18 for exposing the photosensitive material is disposed above the moving stage 14. The exposure head unit 18 includes multiple exposure heads 26. Each exposure head 26 has an optical fiber bundle 28, which is drawn from the light source unit 16, connected thereto.
The exposing apparatus 10 includes a gate-shaped frame 22 which straddles the base 12, and a pair of position detection sensors 24 disposed at one side of the frame 22. The position detection sensors 24 provide a detection signal to the controlling unit 20 when they detect passage of the moving stage 14.
The exposing apparatus 10 further includes two guides 30 disposed on the upper surface of base 12 and extending in the direction of movement of the stage. The moving stage 14 is mounted on the two guides 30 so that it can reciprocate along the guides 30. The moving stage 14 is moved by a linear motor (not shown) at a relatively low constant speed, such as 40 mm/second, over a travel distance of 1000 mm, for example.
In the exposing apparatus 10, a photosensitive material (substrate) 11, which is a member to be exposed, placed on the moving stage 14 is moved relative to the fixed exposure head unit 18 to effect scan exposure.
As shown in
An exposure area 32 of the exposure heads 26 is, for example, a rectangle with short sides in the scanning direction. In this case, a band-like exposed area 34 is formed on the photosensitive material 11 by each exposure head 26 along with the movement for effecting the scan exposure.
Further, as shown in
As shown in
At the data processing means in the controlling unit 20, a control signal for driving each micromirror within an area to be controlled of the DMD 36 of each exposure head 26 is generated based on the inputted image data. Further, the mirror driving means serving as a DMD controller controls the angle of the reflecting surface of each micromirror in the DMD 36 of each exposure head 26, based on the control signal generated at the data processing means. The control on the angle of the reflecting surface will be described later.
As shown in
Although not shown in the drawings, the light source unit 16 contains multiple combining modules for combining laser light emitted from multiple semiconductor laser chips and input the combined light to the optical fibers. The optical fibers extending from each combining module serve as combining optical fibers for propagating the combined laser light, and the multiple optical fibers are bundled to form the optical fiber bundle 28.
As shown in
As shown in
The SRAM cell 44 of a silicon gate CMOS, which is produced on a usual semiconductor memory production line, is disposed just under the micromirror 46 via the supporting post including a hinge and a yoke (not shown).
As a digital signal is written in the SRAM cell 44 of the DMD 36, the micromirror 46 supported by the supporting post is tilted around the diagonal line within a range of ±a degrees (±10 degrees, for example) with respect to the substrate on which the DMD 36 is disposed.
It should be noted that
The DMD 36 may be disposed such that the direction of the short sides thereof is slightly inclined with respect to the scanning direction to form a predetermined angle (ranging from 0.1° to 0.5°, for example) therebetween.
The DMD 36 includes a number of (600, for example) rows of micromirrors arranged in the short-side direction, each row including a number of micromirrors 46 (800, for example) in the long-side direction (the direction of the row). By tilting the DMD 36 as shown in
It should be noted that, in stead of tilting the DMD 36, the rows of micromirrors can be offset from each other in a direction perpendicular to the scanning direction by a predetermined distance to obtain the same effect.
Next, the projection optical system (imaging optical system) disposed on the light-reflecting side of the DMD 36 in the exposure head 26 will be explained. As shown in
The lens systems 50, 52 are configured as an enlarging optical system, which enlarges the sectional area of a bundle of rays reflected by the DMD 36 to enlarge the area of the exposure area 32 on the photosensitive material 11 (shown in
As shown in
The microlens array 54 is formed as a rectangle flat plate, and each portion thereof forming the microlens 60 has an integrally-disposed aperture 62. The aperture 62 is configured to serve as an aperture stop for each corresponding microlens 60.
As shown in
In the exposing apparatus 10 having the above-described configuration, a drawing distortion amount detecting means is provided for appropriately detecting an amount of drawing distortion due to distortion of the lens systems 50, 52 and/or the objective lens systems 56, 58 in the projection optical system of the exposure head 26, and/or changes in temperature during exposure operation at the exposure head 26.
As a part of the drawing distortion amount detecting means, the exposing apparatus 10 includes a beam position measuring means for measuring positions of the applied beams, disposed at the upstream in the conveyance direction of the moving stage 14, as shown in
The beam position measuring means includes a slit plate 70 attached integrally to an upstream edge of the moving stage 14 along the direction perpendicular to the conveyance direction (scanning direction), and photosensors 72 disposed at the back side of the slit plate 70 correspondingly to slits of the slit plate 70.
The slit plate 70 has detection slits 74, through which the laser beams emitted from the exposure head 26 pass.
The slit plate 70 may be formed of quartz glass, which is not likely to deform due to changes in temperature.
As shown in
Namely, the first slit portion 74a and the second slit portion 74b are perpendicular to each other, and the first slit portion 74a forms an angle of 135 degrees with respect to Y-axis (the direction of travel) and the second slit portion 74b forms an angle of 45 degrees with respect to the Y-axis. It should be noted that, in this embodiment, the scanning direction corresponds to the Y-axis and, and the direction perpendicular to the scanning direction (the direction of the rows of exposure heads 26) corresponds to X-axis.
It should be noted that the first slit portion 74a and the second slit portion 74b only need to be arranged to form a predetermined angle therebetween, and may not necessarily intersect with each other. The first slit portion 74a and the second slit portion 74b may be apart from each other.
In this exposing apparatus, in order to obtain good S/N to allow highly accurate measurement even if a beam spot BS to be measured by the beam position measuring means has a low amount of light, a slit width of the first slit portion 74a and the second slit portion 74b of the detection slit 74 is formed to be greater than the diameter of the beam spot BS of a Gaussian beam so that the photosensor 72 can receive a sufficient amount of light. In short, the slit width of the first slit portion 74a and the second slit portion 74b of the detection slit 74 is formed to be greater than the beam spot BS of the Gaussian beam.
By forming the slit width of the detection slit 74 to be greater than the diameter of the beam spot BS so that the photosensor 72 can receive a sufficient amount of light, the amount of light of the beam applied at the beam spot BS can fully be utilized to increase the amount of light received by the photosensor 72 as large as possible. Thus, good S/N can be obtained.
As generally defined, the Gaussian beam refers to a beam that has a Gaussian distribution, which is symmetrical about the center, in the intensity at the cross section perpendicular to the beam.
Further, the diameter of the beam spot of the Gaussian beam refers to a diameter of an area in which the intensity of the beam is not less than 1/e2 (about 13.5%) of the intensity at the central axis of the beam.
The photosensor 72 (CCD, CMOS, photodetector, or the like) for detecting the light from the exposure head 26 is disposed at a predetermined position just below each detection slit 74.
As shown in
The linear encoder 76 can be a commercially-available linear encoder. The linear encoder 76 includes a scale plate 78, which is integrally attached at the side of the moving stage 14 along the conveyance direction (scanning direction) of the moving stage 14 and has a scale formed by equally-spaced small slits provided in a flat portion for allowing light to pass therethrough, as well as a projector 80 and a photoreceiver 82 which are provided at the base 12 on the opposite sides of the scale plate 78 and fixed to a fixing frame (not shown).
The linear encoder 76 is configured such that the projector 80 emits a measurement beam and the photoreceiver 82 disposed at the opposite side detects the measurement beam passing through the slits of the scale plate 78 and sends detection signals to the controlling unit 20.
At the linear encoder 76, as the moving stage 14 is moved from the initial position, the measurement beam emitted from the projector 80 enters the photoreceiver 82 with being intermittently blocked by the scale plate 78 moving together with the moving stage 14.
Then, in the exposing apparatus 10, the controlling unit 20 counts the number of receptions of the beam at the photoreceiver 82 to identify the position of the moving stage 14.
The controlling unit 20 of the exposing apparatus 10 includes an electrical system which forms a part of the distortion amount detecting means.
The controlling unit 20 includes a CPU and a memory serving as a control device. The control device is configured to be able to drive the individual micromirrors 46 of the DMD 36.
The control device receives the output signals from the photoreceiver 82 of the linear encoder 76 and the output signals from the photosensors 72, and applies distortion correction to the image data based on information associating positions of the moving stage 14 with states of the output from the photosensor 72. Then, the control device generates appropriate control signals to control the DMD 36, and drives the moving stage 14 carrying the photosensitive material 11 in the scanning direction.
The control device also controls various units relating to the entire exposure operation of the exposing apparatus 10 and necessary for the exposure at the exposing apparatus 10, such as the light source unit 16.
Next, a method for measuring a beam position using the detection slits 74 and the linear encoder 76 at the drawing distortion amount detecting means provided in the exposing apparatus 10 will be explained.
First, explanation is given on how the actual position of a beam spot formed on the exposure surface when a certain pixel Z1, which is a pixel to be measured, is turned on is identified using the detection slits 74 and the linear encoder 76 in the exposing apparatus 10.
Initially, the moving stage 14 is moved to position a predetermined detection slit 74, which corresponds to a predetermined exposure head 26, of the slit plate 70 below the exposure head unit 18.
Subsequently, control is exerted such that only the certain pixel Z1 of a predetermined DMD 36 is turned on (“on” state).
Then, the moving stage 14 is further moved so that the detection slit 74 is moved to a required position in the exposure area 32 (for example, a position to be the point of origin), as shown by the solid line in
Then, as shown in
Then, the control device calculates positional information of the certain pixel Z1 from a relationship between the position of the moving stage 14 and an output signal outputted when the slit 74 passes the position shown by the imaginary line at the right in
In the beam position measuring means, since the slit width of the detection slit 74 is formed to be sufficiently greater than the diameter of the beam spot BS, the maximum detection value is obtained by the photosensor 72 at positions within a certain range as shown in
Therefore, a half value which is a half the maximum value detected by the photosensor 72 is calculated. Then, the control device finds two positions (positions of the moving stage 14) at which the output from the photosensor 72 is the half value based on the detection values outputted from the linear encoder 76 while the moving stage 14 continuously moves.
Then, a center position between a first position a and a second position b of the two positions at which the output from the photosensor 72 is the half value is calculated. The calculated center position is taken as the positional information of the certain pixel Z1 (the intersection point (X0,Y11) of the first slit portion 74a and the second slit portion 74b). In this manner, the center position of the beam spot BS as the position of the certain pixel Z1 can be found.
The positional information (X0,Y11) of the certain pixel Z1 can be obtained as described above. However, if the relative positional relationship between the detection slit 74 and the exposure head 26 is deviated due to, for example, disturbance during measurement by the beam position measuring means, precise positional information of the certain pixel Z1 cannot be obtained without correcting the positional deviation. Therefore, in the exposing apparatus of this embodiment, correction of the positional deviation due to disturbance as described above is carried out. That is, a precise beam position is determined by calculating the beam position with synchronizing the “positional information measured by the detection slit” and a “relative positional movement value between the moving stage and the exposure head (a measurement value taking all of an external measurement by end-measuring machines, a feed amount of the moving stage and disturbance into account)”.
Specifically, first, a relative positional deviation between the exposure head 26 and the detection slit 74 is measured.
The relative positional deviation between the exposure head 26 and the detection slit 74 is measured by measuring a positional deviation of the moving stage 14 at which the detection slit 74 is provided and a positional deviation of the exposure head 26. As shown in
Then, the first position a is corrected based on the positional deviation measured by the end-measuring machines shown in
Y11a′=Y11a+(Y2a−Y1a)×m/n+(Xa−Xha)/tanθ−(Yh1a×s+Yh2a×r)/(r+s)
wherein:
It should be noted that n+1 detection slits 74 are arranged at regular intervals in the X-direction, and the first position a is measured at the m-th slit from the measurement point of the end-measuring machine Y1.
Further, as shown in
Similarly, a corrected positional coordinate Y11b′ of the second position b is obtained by calculating the formula below:
Y11b′=Y11b+(Y2b−Y1b)×m/n+(Xb−Xhb)/tanθ−(Yh1b×s+Yh2b×r)/(r+s)
wherein:
Then, a center position between the thus obtained positional coordinates Y11a′ and Y11b′ is stored in the memory as positional information (X0,Y11′) of the corrected certain pixel Z1.
Subsequently, the moving stage 14 is moved to move the detection slit 74 along the Y-axis to the left in
Subsequently, the control device reads out the coordinates (X0,Y11′) and (X0,Y12′) stored in the memory and obtains coordinate (X1,Y1) of the certain pixel Z1 according to the following formula:
X1=X0+(Y11′−Y12′)/2
Y1=(Y11′+Y12′)/2
It should be noted that, although the detection slit 74 formed by the first slit portion 74a and the second slit portion 74b is used to find the coordinates X1, Y1 of the certain pixel Z1 in the above-described embodiment, the invention is not limited to this embodiment. For example, the detection slit 74 maybe formed by three slit portions including a first slit portion 74a, a second slit portion 74b and a third slit portion 74c, as shown in
Further, the detection slit 74 may be formed by six slit portions including a first slit portion 74a, a second slit portion 74b, a third slit portion 74c, a fourth slit portion 74d, a fifth slit portion 74e and a sixth slit portion 74f, as shown in
Next, a method for detecting an amount of drawing distortion in the exposure area 32 of one exposure head 26 in the exposing apparatus 10 will be explained.
In order to detect the distortion amount in the exposure area 32, the exposing apparatus 10 is configured such that multiple (five in this embodiment) detection slits 74A-74E are simultaneously used for position detection for one exposure area 32, as shown in
In this case, multiple pixels to be measured, which are regularly distributed over the exposure area to be measured, are set within the exposure area 32 of one exposure head 26. In this embodiment, five sets of pixels to be measured are set. These pixels to be measured are set at symmetrical positions with respect to the center of the exposure area 32. In the exposure area 32 shown in
Further, as shown in
To detect the distortion amount in the exposure area 32, the control device controls the DMD 36 to set the predetermined group of pixels to be measured (Za1, Za2, Za3, Zb1, Zb2, Zb3, Zc1, Zc2, Zc3, Zd1, Zd2, Zd3, Ze1, Ze2 and Ze3) in the “on” state and move the moving stage 14 with the slit plate 70 to a position directly below each exposure head 26 to find coordinates of the pixels to be measured using their corresponding detection slits 74A, 74B, 74C, 74D and 74E. At this time, the predetermined group of pixels to be measured may be set in the “on” state one by one, or all the pixels to be measured of the predetermined group may be set in the “on” state for detection.
Then, the control device finds an amount of drawing distortion (distortion condition) in the exposure area 32, as shown in the example of
In the exposing apparatus 10 of this embodiment, since the multiple detection slits 74 are arranged in the X-direction, an amount of drawing distortion in the exposure area 32 of one exposure head 26 can be detected in the manner as described above. In addition, a positional relationship between adjacent exposure heads 26 can be found.
As shown in
However, in a case where drawing distortion is introduced in an image corresponding to one head due to factors such as temperature and/or vibration during exposure the emitted beams, the image 99 exposed by the exposure area 32 will deform as shown in
The image data to be inputted to the DMD 36 is corrected as shown in
Next, operation of the exposing apparatus 10 having the above-described configuration will be explained.
Although not shown in the drawings, in the light source unit 16 which is a fiber array light source provided in the exposing apparatus 10, laser beams, such as ultraviolet rays, emitted from the laser light emitting devices in a form of divergent rays are collimated by a collimator lens and condensed by a condenser lens, and enter an input end of a core of a multimode optical fiber to propagate through the optical fiber. The beams are combined into a single laser beam at a laser output end and the combined beam is emitted from the optical fiber 28 coupled to the output end of the multimode optical fiber.
In this exposing apparatus 10, image data according to an exposure pattern is inputted to the controlling unit 20 connected to the DMD 36, and is temporarily stored in the memory in the controlling unit. The image data represents density values of pixels forming the image in binary values (i.e., whether or not a dot is recorded at the pixel). The image data is appropriately corrected by the control device based on the amount of drawing distortion (distortion condition) detected by the drawing distortion amount detecting means as described above.
The moving stage 14 holding the photosensitive material 11 on the surface thereof by applying suction is moved along the guides 30 from the upstream to the downstream in the conveyance direction at a constant speed by a driving device (not shown). As the moving stage 14 passes below the gate-shaped frame 22, the position detection sensors 24 fixed to the gate-shaped frame 22 detect the leading edge of the photosensitive material 11, and then the image data stored in the memory, which has been corrected based on the amount of drawing distortion detected by the drawing distortion amount detecting means, is sequentially read out for every multiple lines, and a control signal is generated for each exposure head 26 based on the read out image data at the control device serving as a data processing unit. It should be noted that the above-described correction based on the amount of drawing distortion (distortion condition) detected by the drawing distortion amount detecting means may be carried out when the control signal for each exposure head 26 is generated at the control device based on read-out image data which has not yet been corrected. Then, based on the generated control signal, each micromirror of the spatial light modulating element (DMD) 36 of each exposure head 26 is controlled on or off.
As the laser light is applied from the light source unit 16 to the spatial light modulating element (DMD) 36, the laser beams reflected by the “on”-state micromirrors of the DMD 36 are focused on appropriately corrected exposure positions for drawing. In this manner, the laser light emitted from the light source unit 16 is turned on or off for each pixel to expose the photosensitive material 11.
As the photosensitive material 11 moves together with the moving stage 14 at a constant speed, the photosensitive material 11 is scanned by the exposure head unit 18 in the direction opposite to the direction of movement of the stage, and the band-like exposed area 34 (shown in
When the scanning of the photosensitive material 11 by the exposure head unit 18 is completed and the position detection sensors 24 detect the trailing edge of the photosensitive material 11, the moving stage 14 is returned by the driving device (not shown) along the guides 30 to the point of origin at the most upstream side in the conveyance direction, and is again moved along the guides 30 from the upstream to the downstream in the conveyance direction at a constant speed.
Although the DMD is used as the spatial light modulating element for use in the exposure head 26 in the exposing apparatus 10 according to this embodiment, for example, MEMS (Micro Electro Mechanical Systems)-type spatial light modulating element (SLM: Special Light Modulator), or a spatial light modulating element other than MEMS-type spatial light modulating elements such as an optical element (PLZT device) that modulates light transmitting therethrough by an electro-optic effect or a liquid crystal optical shutter (FLC) may be used in stead of the DMD.
It should be noted that MEMS is a collective term referring to micro-systems, in which micro-sized sensors, actuators and control circuits are integrated, which are produced using micromachining technology based on IC production process. The MEMS-type spatial light modulating element refers to a spatial light modulating element driven by electromechanical operation using electrostatic force.
Further, in the exposing apparatus 10 according to this embodiment, the spatial light modulating element (DMD) 14 used in the exposure head 26 may be replaced with means for selectively turning on or off multiple pixels (means for selectively modulating multiple pixels). The means for selectively turning on or off multiple pixels may be formed, for example, by a laser light source that can selectively turn on or off laser beams corresponding to the pixels, or by a laser light source in which small laser emitting surfaces are arranged correspondingly to the pixels to form a surface emitting laser device, and the small laser emitting surfaces can be selectively turned on or off.
Furthermore, although the beam position is measured by detecting the beam passing through the detection slit 74 by the photosensor 72 in the exposing apparatus 10 according to this embodiment, the invention is not limited to this embodiment. For example, the beam position may be measured using a CCD or a four-section photodetector.
According to the method and apparatus for measuring a drawing position of the invention, a drawing position measuring method for measuring a position of a drawing point by a position measuring means disposed at the drawing surface when a drawing surface and a drawing point forming means for modulating incoming light and forming the drawing point on the drawing surface are moved relatively to each other and the drawing point forming means sequentially forms the drawing point on the drawing surface to draw an image during the relative movement is provided, in which a relative positional deviation between the drawing point forming means and the position measuring means is measured during the relative movement caused by the moving means, and the position of the drawing point measured by the position measuring means is corrected based on the measured positional deviation. Thus, even if a relative positional relationship between the position measuring means and the drawing point forming means is deviated by disturbance such as vibration, for example, the position of the drawing point can be corrected based on the positional deviation. This allows precise measurement of the position of the drawing point, thereby allowing drawing of a high precision image.
Number | Date | Country | Kind |
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222187/2006 | Aug 2006 | JP | national |