JP2012073188A - Light quantity determination device, position detecting device, drawing device, and method for determining light quantity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an art capable of easily determining an appropriate value of an emission light quantity when the position of a target surface is detected by applying light to the target surface and detecting the reflected light.SOLUTION: This light quantity determination device intermittently applies light from a light source to an object surface (an upper face of a substrate W) moving relative to the light source, while changing the emission light quantity, allows a light receiving unit to acquire light quantity distribution data of the reflected light, and sequentially acquires as sample data, the light quantity distribution data of the reflected light reflected at different positions P(1), P(2),...P(N) in the target surface. Subsequently, sample data whose light quantity is within a tolerance are extracted from the plurality of acquired sample data as valid data, and a maximum emission light quality giving the valid data is defined as an optimal emission light quantity value of the position detection light source for detecting the position.

Description

  The present invention relates to a technique for determining the amount of light emitted from a light source for detection in detecting the position of the target surface by irradiating light from the light source for detection onto the target surface and detecting the reflected light.

  One method of detecting the position of the target surface (for example, the relative position of the target surface with respect to a reference point) is a method of irradiating the target surface with light and detecting the reflected light. This method will be briefly described. In this method, for example, as shown in FIG. 19, light (for example, laser light) is incident on the target surface 900 from the detection light source 901 at a predetermined incident angle θ, and the reflected light is received by the light receiving unit 902. Receive light. Now, when the target surface 900 is at the reference position h, it is known that the light receiving position of the reflected light at the light receiving unit 902 becomes the reference position c, and the coordinate value of the reference position c is stored in advance. Here, when the relative position of the target surface 900 is at a position h ′ shifted from the reference position h, the light receiving position of the reflected light at the light receiving unit 902 moves to a position c ′ shifted from the reference position c. That is, when the light receiving position of the reflected light in the light receiving unit 902 is seen, it can be specified how much the target surface 900 is deviated from the reference position h. Therefore, for example, if the relative position of the reference position h with respect to the reference point is stored in advance, the relative position of the target surface 900 with respect to the reference point can be specified.

  This technique is used in various devices. For example, a so-called “direct drawing device” (a type of exposure that irradiates a substrate coated with a photosensitive material and draws a pattern (exposure pattern) directly on the surface (target surface) of the substrate from CAD data or the like. In the apparatus, when the pattern is drawn by irradiating the target surface with light, the position of the target surface is detected by the above-described method, and the position of the lens included in the optical head is adjusted according to the detection result. "Autofocus" is performed.

  By the way, in the direct drawing apparatus, it is necessary to draw a fine pattern on the surface of the substrate that is the target surface with high accuracy, and for that purpose, it is necessary to perform autofocus with high accuracy. In order to perform autofocus with high accuracy, the position of the target surface must be detected with high accuracy.

  For example, Patent Document 1 discloses a technique for improving the position detection accuracy of the target surface. According to the technique disclosed herein, a light receiving unit acquires a plurality of received light images of reflected light, and integrates the acquired plurality of received light images, whereby there is a pattern element on the target surface. The position of the target surface can always be detected with high accuracy.

  By the way, in order to specify the position of the target surface with high accuracy, it is necessary to increase the accuracy of specifying the reflected light receiving position. There is a situation that the accuracy of specifying the position is deteriorated. That is, in order to specify the position of the target surface with high accuracy, the received light intensity of the reflected light needs to be within an appropriate range.

  If the received light intensity of the reflected light is within an appropriate range, the amount of light emitted from the light source for detection may be set in advance by calculating backward from the reflectance of the target surface. However, it is actually very difficult and time-consuming to specify the amount of emitted light so that reflected light with a light reception intensity within an appropriate range can be obtained.

  This is because the reflectance of the surface of the substrate that is the target surface depends on the surface state of the substrate (for example, the surface material, the type of photosensitive material applied to the surface, the thickness of the photosensitive material applied to the surface, etc.) Therefore, even if the amount of emitted light is appropriate for a substrate with a certain surface condition, it cannot be said that the amount of emitted light is appropriate for a substrate with a slightly different surface condition (that is, the appropriate amount of emitted light is This depends on the surface condition of the substrate.

  Also, even if the same substrate is affected by the pattern formed on the surface, there is a local area with relatively low (or high) reflectance. Even if the reflected light is obtained with the received light intensity, the reflected light cannot be obtained with the received light intensity within an appropriate range in another region, and the position detection accuracy may deteriorate in that region. That is, when specifying an appropriate amount of emitted light, it must be determined after taking into account the deviation of the reflectance existing in the entire substrate.

  Conventionally, the amount of light emitted from the detection light source is generally determined by an experienced operator based on experience. However, as described above, it is not easy even for a skilled operator to determine a set value that appropriately corresponds to the surface state of the substrate. Further, even a skilled operator can hardly determine the amount of emitted light on a constant basis, and as a result, the accuracy of position detection cannot be stabilized at a high level.

  For example, in Patent Document 2, the position detection process is performed while changing the amount of light emitted from the light source for detection stepwise. According to this configuration, for example, even if the preset amount of emitted light does not strictly correspond to the surface state of the substrate, there is a high possibility that reflected light having a received light intensity within an appropriate range can be obtained.

JP 2008-258365 A JP 2009-244380 A

  As described above, according to the technique of Patent Document 2, although it is easy to obtain reflected light with a light reception intensity within an appropriate range, there is a limit to the range in which the amount of light emitted from the light source for detection can be changed in the position detection process. When the initial value of the amount of emitted light is set to a value that does not match when viewed from the surface state of the substrate, even if the amount of emitted light is changed from there, it is possible to obtain almost all reflected light within the appropriate range of received light intensity. Will not be able to. That is, even when the technique of Patent Document 2 is applied, it is important to set the initial value of the amount of emitted light to a value that appropriately corresponds to the surface state of the substrate. Then, as described above, it is not easy to determine the initial value as a value that appropriately corresponds to the surface state of the substrate.

  The present invention has been made in view of the above problems, and in detecting the position of the target surface by irradiating the target surface with light from the detection light source and detecting the reflected light, the detection light source It is an object of the present invention to provide a technique capable of easily determining an appropriate amount of emitted light.

  According to the first aspect of the present invention, in detecting the position of the target surface by irradiating the target surface with light from the detection light source and detecting the reflected light, the amount of light emitted from the detection light source is determined. A light amount determination device that receives light reflected from the target surface of the light source that emits light toward the target surface, and obtains light amount distribution data of the reflected light A light receiving unit that performs relative movement between the light source and the target surface, and the target surface that moves relative to the light source from the light source. In addition, the light amount distribution data of the reflected light is acquired by the light receiving unit, and the light amount distribution data of the reflected light reflected at different positions in the target surface is sequentially acquired as sample data. Data collection unit , Among the plurality of sample data acquired by the data collection unit, those having a received light amount within an allowable range are extracted as effective data, and the maximum emitted light amount given the effective data is extracted as the emitted light amount of the light source for detection An optimal value acquisition unit that acquires the optimal value of

  Invention of Claim 2 is the light quantity determination apparatus of Claim 1, Comprising: When the sample data acquired previously is the said effective data, the said data collection part is the emitted light quantity of the said light source. If the previously acquired sample data is light quantity excess data whose received light amount is larger than the allowable range without changing, the emitted light quantity of the light source is changed small, and the previously acquired sample data is If the received light amount is less light amount data than the allowable range, the emitted light amount of the light source is greatly changed.

  The invention according to claim 3 is the light amount determination device according to claim 2, wherein the sample data obtains an effective detected light amount from an area corresponding to a predetermined length or more on the target surface. If it is the light quantity distribution data, the sample data is determined as the excessive light quantity data.

  The invention according to claim 4 is the light quantity determination device according to claim 2 or 3, wherein when the sample data is light quantity distribution data giving 0 as a center of gravity, the sample data is converted into the light quantity under-data. Judge.

  A fifth aspect of the present invention is the light quantity determination device according to any one of the first to fourth aspects, wherein the sample data includes all or part of the plurality of sample data acquired by the data collection unit. An evaluation unit that evaluates the optimum value obtained based on the plurality of sample data based on the group is further provided.

  The invention according to claim 6 is the light quantity determination device according to claim 5, wherein the number of pieces of sample data in which the evaluation unit continuously acquires sample data that is not the valid data in the sample data group is a predetermined number. Give a negative rating if greater than.

  The invention according to claim 7 is the light quantity determination apparatus according to claim 5 or 6, wherein the evaluation unit has an excessive light quantity in which the amount of received light is larger than the allowable range with respect to the entire sample data group. A negative evaluation is given when the proportion of sample data taken as data is greater than a predetermined value.

  Invention of Claim 8 is the light quantity determination apparatus in any one of Claim 5-7, Comprising: The ratio for which the said effective data occupies the said evaluation part with respect to the whole said sample data group. A negative evaluation is given if it is smaller than a predetermined value.

  The invention according to claim 9 is the light quantity determination device according to any one of claims 1 to 8, wherein the data collection unit repeats a data collection process of acquiring the plurality of sample data a plurality of times. Executing the initial light source in the data collection process to be executed next, using the maximum amount of emitted light given the effective data among the plurality of sample data acquired in the data collection process executed previously. Set to value.

  A tenth aspect of the present invention is the light amount determining apparatus according to the ninth aspect, wherein the data collection unit executes the step size for changing the emitted light amount in the data collection process first. The value is smaller than the step size in the collection process.

  The invention according to claim 11 is a position detection device that detects the position of the target surface by irradiating the target surface with light from a light source for detection and detecting the reflected light. A light source that emits light toward the light source, a light receiving unit that receives light reflected from the target surface of the light emitted from the light source, and obtains light amount distribution data of the reflected light, and the light source and the target surface. The light is intermittently emitted from the light source to the target surface that moves relative to the light source while changing the amount of emitted light, and the reflected light The light collection unit acquires the light amount distribution data, and the data collection unit sequentially obtains the light amount distribution data of the reflected light reflected at different positions in the target surface as sample data, and the data collection unit Multiple samples An optimum value acquisition unit that extracts, as the effective data, the received light amount within the allowable range, and obtains the maximum emitted light amount given the effective data as the optimum value of the emitted light amount of the detection light source When detecting the position of the target surface, light is emitted from the detection light source with a light amount defined by the optimum value acquired by the optimum value acquisition unit.

  The invention according to claim 12 is a drawing apparatus that draws a pattern on the target surface by irradiating light from the optical head to a target surface that moves relative to the optical head, Based on the position detection unit that detects the position of the target surface by irradiating the target surface with light from the detection light source and detecting the reflected light, and the position of the target surface detected by the position detection unit A position adjusting unit that adjusts a position of the optical system of the optical head with respect to the target surface, and the position detecting unit emits light toward the target surface, and the light emitted from the light source A light receiving unit that receives reflected light from the target surface and acquires light amount distribution data of the reflected light, a transport unit that relatively moves the light source and the target surface, and the light source. The pair moving relative to The surface is irradiated with light intermittently while changing the amount of emitted light, and the light amount distribution data of the reflected light is acquired by the light receiving unit, and the amount of reflected light reflected at different positions in the target surface. A data collection unit that sequentially acquires distribution data as sample data, and a plurality of sample data acquired by the data collection unit that has received light amount within an allowable range is extracted as valid data, and the valid data An optimum value acquisition unit that obtains the maximum emitted light amount given as an optimum value of the emitted light amount of the light source for detection, and when detecting the position of the target surface, from the light source for detection, the optimum value Light is emitted with an amount of light defined by the optimum value acquired by the acquisition unit.

  The invention according to claim 13 determines the amount of light emitted from the light source for detection when detecting the position of the target surface by irradiating the target surface with light from the light source for detection and detecting the reflected light. A) a method for determining the amount of light to be emitted, wherein light is intermittently irradiated from a light source to the target surface moving relative to the light source while changing the amount of emitted light, and the amount of reflected light A step of causing the light receiving unit to acquire distribution data and sequentially acquiring light amount distribution data of reflected light reflected at different positions in the target surface as sample data; b) a plurality of acquired in the step a) Among the sample data, the data whose received light amount is within an allowable range is extracted as effective data, and the maximum emitted light amount given the effective data is obtained as the optimum value of the emitted light amount of the detection light source. Provided that the step.

  According to the invention described in claims 1 to 13, a plurality of sample data is acquired by irradiating light from a light source to different positions on the target surface while changing the amount of emitted light. Then, the maximum amount of emitted light to which valid data is given is obtained as the optimum value of the amount of emitted light from the detection light source among the plurality of sample data obtained. If the position of the target surface is detected using the optimum value here, it is highly possible that reflected light with an amount of received light within an allowable range is obtained, so that the position of the target surface can be detected with high accuracy. In particular, the reflected light whose received light amount is less than or equal to the allowable range causes the detection accuracy of the position of the target surface to be greatly deteriorated, and the possibility that such reflected light is obtained is reduced. That is, according to this configuration, it is possible to easily determine an appropriate value of the amount of emitted light corresponding to the surface state of the target surface (the position of the target surface can be detected with high accuracy).

  In particular, according to the second aspect of the present invention, in a series of processes for acquiring a plurality of sample data, if the previously acquired sample data is excessive light amount data, the emitted light amount is changed small, When the acquired sample data is data with an insufficient amount of light, the amount of emitted light is greatly changed, so that there is a high possibility that a lot of effective data can be acquired as sample data. Therefore, it is possible to efficiently determine an appropriate amount of emitted light corresponding to the state of the target surface.

  In particular, according to the invention described in claim 5, based on the sample data group composed of all or part of the plurality of sample data acquired by the data collection unit, the optimum obtained based on the plurality of sample data Since the value is evaluated, when the optimum value is obtained based on an inappropriate data collection process, it can be detected. Therefore, it is possible to avoid a risk that an optimum value with low reliability is set as the amount of emitted light as it is.

  In particular, according to the invention described in claim 9, among the plurality of light quantity distribution data acquired in the previously executed data collection process, the maximum emitted light quantity given effective data is set as the initial value of the light source. Repeat the data collection process. According to this configuration, as the number of executions of the data collection process is increased, the possibility that more effective data can be acquired increases. As a result, the optimum value corresponding to the state of the target surface can be determined with high accuracy.

  In particular, according to the invention described in claim 10, since the step size for changing the amount of emitted light in the data collection process is decreased as the number of repetitions of the data collection process is increased, the optimum value appropriately corresponding to the state of the target surface is set. Further, it can be specified with high accuracy.

It is a side view of a drawing apparatus. It is a top view of a drawing apparatus. It is a figure which shows the structural example of a drawing unit typically. It is a figure which shows typically the structural example of the position detection unit with which an optical head part is provided. It is a figure which shows the mode of light quantity distribution data typically. It is a figure which shows the structural example of an illumination unit. It is a figure which shows the structural example of an alignment unit. It is a figure which shows typically the structural example of a position detection unit. It is a figure which shows the flow of the process performed in a drawing apparatus. It is a figure which shows the flow of a sample data collection process. It is a figure which shows typically the relative positional relationship of the board | substrate and position detection unit in a sample data collection process. It is a figure which shows the flow of the acquisition process of sample data. It is a figure which shows typically the group of light quantity distribution data which a light-receiving part acquires. It is a figure which shows the flow of the process which arranges light quantity distribution data. It is a figure which shows the structural example of a sample data table typically. It is a figure which shows the flow of the evaluation process of a sample data collection process. It is a figure which shows the whole flow of the process which determines an optimal value. It is a block diagram showing each function implement | achieved in a drawing apparatus. It is a figure for demonstrating the principle of the method of detecting the position of a target surface.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, in each figure referred in the following description, in order to clarify the positional relationship and operation direction of each member, the common XYZ orthogonal coordinate system is attached | subjected.

<1. Configuration of Drawing Apparatus 100>
<1-1. Overall configuration>
1 and 2 are a side view and a top view showing a configuration of a drawing apparatus 100 according to an embodiment of the present invention. The drawing apparatus 100 is an apparatus that draws a predetermined pattern by irradiating light on the upper surface of a semiconductor substrate (hereinafter simply referred to as “substrate”) W on which a layer of a photosensitive material such as a resist is formed (so-called “direct drawing apparatus”). ]).

  The drawing apparatus 100 has a configuration in which various constituent elements are arranged inside the main body formed by attaching a cover to the main body frame 101 and outside the main body that is outside the main body frame 101.

  A processing area 102 and a delivery area 103 are formed inside the main body of the drawing apparatus 100. In the processing region 102, a stage 10 that mainly holds the substrate W, a stage moving mechanism 20 that moves the stage 10, a stage position measuring unit 30 that measures the position of the stage 10, and an optical head that irradiates light on the upper surface of the substrate W Part 40, alignment unit 50 for imaging an alignment mark formed on the upper surface of substrate W, and relative position to the reference position on the upper surface of substrate W (a position along the Z direction, hereinafter referred to as "height position") ) Is detected. On the other hand, in the delivery area 103, a transfer device 70 for carrying the substrate W in and out of the processing area is arranged.

  In addition, an illumination unit 80 that supplies illumination light to the alignment unit 50 is disposed outside the main body of the drawing apparatus 100. In addition, a control unit 90 that is electrically connected to each unit included in the drawing apparatus 100 and controls the operation of each unit is disposed outside the main body.

  A cassette placement unit 104 for placing the cassette C is disposed outside the main body of the drawing apparatus 100 and adjacent to the delivery area 103. The transfer device 70 disposed in the delivery area 103 takes out the unprocessed substrate W accommodated in the cassette C placed on the cassette placement unit 104 and carries it into the processing area 102 and has been processed from the processing area 102. The substrate W is unloaded and accommodated in the cassette C. Delivery of the cassette C to the cassette mounting unit 104 is performed by an external transport device (not shown).

<1-2. Configuration of each part>
<Stage 10>
The stage 10 has a flat outer shape, and is a holding unit that places and holds the substrate W in a horizontal posture on the upper surface thereof. A plurality of suction holes (not shown) are formed on the upper surface of the stage 10, and by forming a negative pressure (suction pressure) in the suction holes, the substrate W placed on the stage 10 is moved to the stage 10. It can be fixedly held on the upper surface.

<Stage moving mechanism 20>
The stage moving mechanism 20 is a mechanism that moves the stage 10 in the main scanning direction (Y-axis direction), the sub-scanning direction (X-axis direction), and the rotation direction (rotation direction around the Z axis (θ-axis direction)). The stage moving mechanism 20 includes a rotation mechanism 21 that rotates the stage 10, a support plate 22 that rotatably supports the stage 10, a sub-scanning mechanism 23 that moves the support plate 22 in the sub-scanning direction, and a sub-scanning mechanism 23. And a main scanning mechanism 25 that moves the base plate 24 in the main scanning direction. The rotation mechanism 21, the sub-scanning mechanism 23, and the main scanning mechanism 25 are electrically connected to the control unit 90 and move the stage 10 in accordance with instructions from the control unit 90.

  The rotation mechanism 21 rotates the stage 10 on the support plate 22 around a rotation axis perpendicular to the upper surface of the substrate W.

  The sub-scanning mechanism 23 includes a linear motor 23 a configured by a mover attached to the lower surface of the support plate 22 and a stator laid on the upper surface of the base plate 24. In addition, a pair of guide portions 23 b extending in the sub-scanning direction is provided between the support plate 22 and the base plate 24. For this reason, when the linear motor 23a is operated, the support plate 22 moves in the sub-scanning direction along the guide portion 23b on the base plate 24.

  The main scanning mechanism 25 includes a linear motor 25 a configured by a mover attached to the lower surface of the base plate 24 and a stator laid on the base 106 of the drawing apparatus 100. In addition, a pair of guide portions 25 b extending in the main scanning direction is provided between the base plate 24 and the base 106. For this reason, when the linear motor 25 a is operated, the base plate 24 moves in the main scanning direction along the guide portion 25 b on the base 106.

<Stage position measuring unit 30>
The stage position measurement unit 30 is a mechanism that measures the position of the stage 10. The stage position measurement unit 30 is electrically connected to the control unit 90 and measures the position of the stage 10 in accordance with an instruction from the control unit 90.

  The stage position measurement unit 30 can be configured by, for example, a mechanism that irradiates laser light toward the stage 10 and measures the position of the stage 10 by using interference between the reflected light and the emitted light. In this case, the stage position measurement unit 30 includes, for example, an emission unit 31 that emits laser light, a beam splitter 32, a beam bender 33, a first interferometer 34, and a second interferometer 35. The emission unit 31 and the interferometers 34 and 35 are electrically connected to the control unit 90 and measure the position of the stage 10 according to an instruction from the control unit 90.

  The laser light emitted from the emission unit 31 first enters the beam splitter 32 and is branched into first branched light that goes to the beam bender 33 and second branched light that goes to the second interferometer 35. The first branched light is reflected by the beam bender 33, enters the first interferometer 34, and is irradiated from the first interferometer 34 to the first part of the stage 10. Then, the first branched light reflected at the first part is incident on the first interferometer 34 again. The first interferometer 34 is a positional parameter corresponding to the position of the first part based on the interference between the first branched light traveling toward the first part of the stage 10 and the first branched light reflected by the first part. Measure.

  On the other hand, the second branched light is incident on the second interferometer 35 and the second part (the second part is the first part in the side surface on the −Y side of the stage 10 from the second interferometer 35). It is irradiated at a position different from the part). Then, the second branched light reflected at the second part is incident on the second interferometer 35 again. The second interferometer 35 corresponds to the position of the second part based on the interference between the second branched light traveling toward the second part of the stage 10 and the second branched light reflected by the second part of the stage 10. The measured position parameter is measured.

  The control unit 90 includes a position parameter corresponding to the position of the first part of the stage 10 and a position corresponding to the position of the second part of the stage 10 from each of the first interferometer 34 and the second interferometer 35. Get parameters. Then, the position of the stage 10 is calculated based on each acquired position parameter.

<Optical head part 40>
The optical head unit 40 is a mechanism that irradiates light onto the upper surface of the substrate W held on the stage 10. The optical head unit 40 is provided on a frame 107 laid on the base 106 so as to straddle the stage 10 and the stage moving mechanism 20.

  The optical head unit 40 includes a laser oscillator 41 that emits laser light, a laser drive unit 42 that drives the laser oscillator 41, and light emitted from the laser oscillator 41 into linear light (light beam cross-section) with a uniform intensity distribution. Is an illumination optical system 43. These parts 41, 42, and 43 are disposed inside a box that forms the top plate of the frame 107. Each of these units 41, 42, and 43 is electrically connected to the control unit 90 and operates in accordance with an instruction from the control unit 90.

  The optical head unit 40 further includes a drawing unit 401 that is accommodated in an attachment box attached to the + Y side of the frame 107. The drawing unit 401 forms modulation according to pattern data on the light emitted from the laser oscillator 41 and incident via the illumination optical system 43, and irradiates the upper surface of the substrate W. The configuration of the drawing unit 401 will be described with reference to FIG. FIG. 3 is a diagram schematically illustrating a configuration example of the drawing unit 401.

  The drawing unit 401 includes a spatial modulation unit 44 and a projection optical system 45. The units 44 and 45 included in the drawing unit 401 are electrically connected to the control unit 90 and operate in accordance with instructions from the control unit 90.

  The spatial modulation unit 44 has a plurality of spatial light modulation elements arranged in a line. The spatial light modulation element is an element that modulates light by electrical control. For example, GLV (Grating Light Valve) (Silicon Light Machines (Slit) San Jose, California)). A diffraction grating type spatial light modulation element changes its surface state in accordance with an applied voltage. Specifically, when the voltage is on, the surface state emits zero-order light, and when the voltage is off, the surface state emits first-order diffracted light (± first-order diffracted light). As will be described below, the projection optical system 45 blocks the first-order diffracted light and allows only the zero-order light to pass through. That is, only the 0th order light reaches the upper surface of the substrate W.

  The light emitted from the illumination optical system 43 enters the mirror 431 and enters the spatial modulation unit 44 at a predetermined angle. On the other hand, the control unit 90 applies a voltage to each spatial light modulation element via a driver circuit based on pattern data (CAD data describing a pattern to be drawn on the substrate W). As a result, the light incident on the spatial modulation unit 44 is modulated according to the pattern to be drawn.

  The projection optical system 45 is a functional unit that guides the light spatially modulated in the spatial modulation unit 44 to the surface of the substrate W and forms an image on the surface of the substrate W. For example, the ghost optical system 45 sequentially from the spatial modulation unit 44 side. A light shielding plate 451 that blocks light, two lenses 452 and 453 that configure a zoom unit, a diaphragm plate 454 that blocks high-order diffracted light, and a focusing lens 455 that configures a focusing unit are disposed.

  The light that has passed through the lenses 452 and 453 is guided to a diaphragm plate 454 having an opening. Here, part of the light (0th-order light) passes through the aperture of the diaphragm plate 454 and is guided to the focusing lens 455, and the remaining light (first-order diffracted light) is blocked by the diaphragm plate 464. The light (0th order light) that has passed through the focusing lens 465 is guided to the surface of the substrate W at a predetermined magnification.

  Note that the projection optical system 45 is not necessarily configured by the light shielding plate 451, the lenses 452 and 453, the diaphragm plate 454, and the focusing lens 455, and other optical elements may be added.

  Refer to FIGS. 1 and 2 again. The optical head unit 40 further includes a drive unit 46 that adjusts the position of the focusing lens 455 provided in the projection optical system 45 and the height position of the upper surface of the substrate W (specifically, each position within the upper surface of the substrate W). And a position detection unit 47 for detecting.

  The drive unit 46 linearly moves the focusing lens 455 included in the projection optical system 45 along the Z-axis direction, so that the position of the focusing lens 455 with respect to each position within the upper surface of the substrate W (that is, the upper surface of the substrate W). (Separating distance between each of the positions and the focusing lens 455). The drive unit 46 includes, for example, a rotary motor, a ball screw disposed in parallel with the Z-axis direction, and a nut unit fixed to the support base of the focusing lens 455 (or the housing of the drawing unit 401). A linear motion mechanism can be employed.

  The position detection unit 47 is associated with the optical head unit 40, and is disposed in the vicinity of the corresponding optical head unit 40, so that each position within the upper surface of the substrate W (specifically, the corresponding optical head unit 40). Detects the height position of the position (drawing planned position) where drawing is scheduled. The configuration of the position detection unit 47 will be described in detail later.

  The drive unit 46 and the position detection unit 47 constitute a functional unit (autofocus unit) that performs autofocus. That is, the control unit 90 causes the position detection unit 47 to detect the height position of the drawing-scheduled position, and controls the drive unit 46 based on the acquired position information (hereinafter referred to as “height position information”) to Adjustment is performed so that the focusing lens 455 of the head unit 40 is placed at an appropriate position (a position where the light emitted from the optical head unit 40 is imaged at the planned drawing position).

  Here, the configuration of the position detection unit 47 will be described with reference to FIG. FIG. 4 is a diagram schematically illustrating a configuration example of the position detection unit 47.

  The position detection unit 47 mainly includes a light source 471 and a light receiving unit 472. The light source 471 is constituted by, for example, a laser light source that emits laser light. The light source 471 is connected to the control unit 90 and operates according to an instruction from the control unit 90. The control unit 90 controls the light emission timing from the light source 471, the light emission time, and the amount of emitted light.

  Light emitted from the light source 471 is guided to the upper surface of the substrate W through the illumination optical system 4711 and the mirror 4712. The illumination optical system 4711 and the mirror 4712 cause the light emitted from the light source 471 to enter the upper surface of the substrate W along an axis inclined by a predetermined angle with respect to the normal direction of the upper surface of the substrate W. Light incident on the upper surface of the substrate W and reflected there is guided to the light receiving unit 472 via the mirror 4713, the relay optical system 4714, and the mirror 4715.

  The light receiving unit 472 is configured by a line sensor (for example, a CMOS line sensor or a CCD line sensor), and includes a plurality of pixels arranged in a straight line. Each pixel receives reflected light emitted from the light source 471 and reflected by the upper surface of the substrate W, and thereby, distribution data (hereinafter referred to as “light quantity distribution data”) of the received light intensity of the reflected light is acquired. As schematically shown in FIG. 5, the light amount distribution data includes position information (pixel position) of each pixel that receives reflected light and light amount information (specifically, for example, accumulated voltage) of light received by each pixel. It is data including.

  The control unit 90 calculates the height position of the upper surface (specifically, the reflection position) of the substrate W based on the light amount distribution data acquired by the light receiving unit 472. Here, a process in which the control unit 90 calculates the height position based on the light amount distribution data will be described.

  The control unit 90 outputs a signal from the light receiving unit 472 at a predetermined timing, A / D converts the output signal, and obtains it as light amount distribution data. As illustrated in FIG. 5, the light amount distribution data includes a peak portion where the amount of received light increases rapidly and decreases. This peak portion has a shape like a Gaussian curve, for example. By specifying the position of this peak part (specifically, the position of the pixel corresponding to the peak part), the light receiving position of the reflected light can be specified. That is, when the upper surface of the substrate W is warped or distorted, the peak position is shifted from the reference position, so the reference position of the peak position (specifically, the position of the reference pixel) By calculating the deviation width from the height, the height position of the upper surface (specifically, the reflection position) of the substrate W can be specified.

  When light amount distribution data with appropriate received light intensity is obtained, the peak position is given by the center of gravity. Therefore, when acquiring the light amount distribution data, the control unit 90 calculates the center of gravity of the light amount distribution data, and acquires the position of the pixel corresponding to the center of gravity as the light receiving position. Further, the control unit 90 calculates height position information based on the light receiving position information. Then, the acquired height position information is stored in association with information for specifying the reflection position (hereinafter referred to as “reflection position information”).

  According to the above method, if the light intensity distribution data has an appropriate light reception intensity, the light reception position can be detected with high accuracy (and thus the height position can be detected with high accuracy), but the light reception intensity is too strong (or If it is too weak), the error between the center of gravity and the peak position becomes large, and the detection accuracy of the light receiving position deteriorates (as a result, the detection accuracy of the height position deteriorates). That is, in order to detect the height position with high accuracy, it is necessary for the light receiving unit 472 to obtain light distribution data of the received light intensity within an appropriate range. In order to obtain the light intensity distribution data of the received light intensity within an appropriate range in the light receiving unit 472, it is necessary that the emitted light quantity of the light source 471 is appropriately set corresponding to the surface state of the substrate W. This point will be described in detail later.

<Lighting unit 80>
The illumination unit 80 is connected to the alignment unit 50 via the fiber 801, and supplies illumination light to the alignment unit 50. The configuration of the illumination unit 80 will be described with reference to FIG. FIG. 6 is a diagram illustrating a configuration example of the illumination unit 80.

  The illumination unit 80 includes a halogen lamp 81 connected to the fiber 801 through the rotation filter 82, a rotation filter 82 disposed on the optical path of the light L emitted from the halogen lamp 81 and incident on the fiber 801, and the rotation filter 82. A rotation motor 83 for rotating the motor. The halogen lamp 81 and the rotary motor 83 are electrically connected to the control unit 90 and operate according to instructions from the control unit 90.

  The rotary filter 82 includes a plurality of windows in which different types of filters are fitted, and a single window in which no filter is fitted. Each window is arranged radially about the rotation axis of the rotary filter 82. The various filters fitted in the window are filters that transmit wavelengths in different regions. For example, a filter that transmits visible light is fitted in one window, and a filter that transmits infrared light is fitted in another window.

  The control unit 90 controls the rotation motor 83 according to the wavelength of the light to be supplied to the alignment unit 50 to rotate the rotation filter 82, and on the optical path (on the optical path of the light incident on the fiber 801 from the halogen lamp 81). Change the placement window. For example, when infrared light is to be supplied, the control unit 90 controls the rotary motor 83 to rotate the rotary filter 82 so that a window fitted with a filter that transmits infrared light is disposed on the optical path. . Then, of the light emitted from the halogen lamp 81, only infrared light is transmitted through the filter, and only infrared light is incident on the fiber 801. That is, infrared light is supplied to the alignment unit 50.

<Alignment unit 50>
The alignment unit 50 images the alignment mark formed on the upper surface of the substrate W. The configuration of the alignment unit 50 will be described with reference to FIG. FIG. 7 is a diagram illustrating a configuration example of the alignment unit 50.

  The alignment unit 50 includes a lens barrel 51, an objective lens 52, and a CCD image sensor sensor 53 including, for example, an area image sensor (two-dimensional image sensor).

  The light guided by the fiber 801 extending from the illumination unit 80 is guided to the upper surface of the substrate W via the lens barrel 51, and the reflected light is received by the CCD image sensor 53 via the objective lens 52. Thereby, imaging data of the upper surface of the substrate W is acquired. The CCD image sensor 53 is electrically connected to the control unit 90, acquires imaging data in response to an instruction from the control unit 90, and transmits the acquired imaging data to the control unit 90.

<Position detection unit 60>
The position detection unit 60 detects the height position of the upper surface (target surface) of the substrate W with respect to the reference position. The configuration of the position detection unit 60 will be described with reference to FIG. FIG. 8 is a diagram illustrating a configuration example of the position detection unit 60.

  The configuration of the position detection unit 60 is the same as the configuration of the position detection unit 47 provided in the optical head unit 40. That is, the position detection unit 60 includes a light source 61 and a light receiving unit 62. Further, the position detection unit 60 includes an illumination optical system 601, mirrors 602 and 603, a relay optical system 604, and a mirror 605. Since the structure of each part is the same as that of the position detection unit 47, the detailed description is abbreviate | omitted.

<Control unit 90>
The control unit 90 controls the operation of each unit included in the drawing apparatus 100 while executing various arithmetic processes. The control unit 90 includes, for example, a CPU for performing various arithmetic processes, a ROM for storing a boot program, a RAM serving as a work area for the arithmetic processes, a storage unit (for example, a hard disk) for storing programs and various data files, and the like. It is comprised by the computer provided with the display which performs a display, the input part comprised with a keyboard, a mouse | mouth, etc., the data communication part which has a data communication function via LAN etc., etc. When the computer operates in accordance with a program installed in the computer, the computer functions as the control unit 90 of the drawing apparatus 100. Each functional unit realized in the control unit 90 may be realized by a predetermined program being executed by a computer, or may be realized by dedicated hardware.

  Data (pattern data) describing a pattern to be drawn on the substrate W is stored in the storage unit included in the control unit 90. The pattern data is, for example, CAD data generated using CAD. The control unit 90 acquires pattern data prior to a series of processes for the substrate W and stores the pattern data in the storage unit. The acquisition of pattern data may be performed by receiving from an external terminal device connected via a network or the like, or may be performed by reading from a recording medium.

<2. Flow of processing>
The flow of processing executed in the drawing apparatus 100 will be described with reference to FIG. FIG. 9 is a diagram showing the flow of the processing.

  The processing in the drawing apparatus 100 is performed on a lot basis. When the transport device 70 carries in the first substrate W of the lot to be processed and places it on the stage 10 (step S1), first, the light source 471 (detection light source) of the position detection unit 47 provided in the optical head unit 40. ) To determine the optimum value of the emitted light quantity (step S2), followed by the process of setting the emitted light quantity of the light source 471 (step S3). In the process of step S3, the control unit 90 may set the optimum value determined in step S2 as it is as the emitted light amount of the light source 471, or the control unit 90 may input the value input by the operator via the operation unit. The value received by the control unit 90 may be set as the amount of light emitted from the light source 471. However, in the latter case, the optimum value determined in step S2 is displayed on the display screen so that the operator can determine the amount of light emitted from the light source 471 with reference to the optimum value displayed.

  Subsequently, a drawing process on the substrate W is performed (step S4). In this process, first, an alignment mark is imaged (step S41). Specifically, the stage moving mechanism 20 moves the stage 10 in accordance with an instruction from the control unit 90 to move the substrate W relative to the alignment unit 50, and below the alignment unit 50, The substrate W is moved so that the position where the alignment mark is formed on the substrate W is set. When the substrate W is moved to a predetermined position, the alignment unit 50 images the upper surface of the substrate W in accordance with an instruction from the control unit 90. Thereby, imaging data of the alignment mark is obtained.

  Subsequently, the position of the stage 10 is adjusted (step S42). In this process, the control unit 90 first specifies the position and orientation of the substrate W with respect to the stage 10 based on the imaging data obtained in step S41. When the position and orientation of the substrate W with respect to the stage 10 are specified, the control unit 90 controls the stage position measurement unit 30 and the stage moving mechanism 20 so that the substrate W placed on the stage 10 is transferred to the optical head unit 40. The position of the stage 10 is adjusted so that the position and orientation determined with respect to it are obtained.

  When the processing in step S42 is completed, pattern drawing on the substrate W is subsequently executed (step S43). In this process, first, the stage moving mechanism 20 moves the stage 10 along the main scanning direction (Y-axis direction) in accordance with an instruction from the control unit 90, whereby the substrate W is moved to the optical head unit 40. On the other hand, it is moved relatively along the main scanning direction (main scanning). While the substrate W is relatively moved along the main scanning direction, the optical head unit 40 directs light, on which modulation according to rasterized pattern data is formed, to the substrate W under the control of the control unit 90. Irradiate. When the end on the + Y side of the substrate W passes below the optical head unit 40, one main scan is completed. When one main scan is completed, one stripe is drawn on the upper surface of the substrate W.

  When one main scanning is completed, the stage moving mechanism 20 moves the stage 10 along the sub-scanning direction (X-axis direction) by a distance corresponding to the width of one stripe, thereby moving the substrate W to the optical head unit. It is moved relative to 40 along the sub-inspection direction (sub-scanning).

  When the sub-scanning is finished, the main scanning is performed again. As a result, another stripe is drawn next to the drawing area for one stripe drawn in the previous main scanning. In this way, the pattern is drawn over the entire upper surface of the substrate W by repeatedly performing the main scanning and the sub-scanning.

  While the optical head unit 40 is drawing a pattern on the substrate W, the control unit 90 causes the position detection unit 47 and the drive unit 46 to perform autofocus.

  Specifically, the control unit 90 irradiates light from the light source 471 of the position detection unit 47 with the emitted light amount set in step S3. The emitted light is reflected by the upper surface of the substrate W, and the reflected light is received by the light receiving unit 472. The control unit 90 detects the height position of the upper surface (specifically, the reflection position) of the substrate W based on the light amount distribution data of the reflected light acquired by the light receiving unit 472, and reflects the acquired height position information. It is stored in association with the position information. On the other hand, the control unit 90 controls the driving unit 46 to adjust the position of the focusing lens 455. Specifically, the height position information stored in association with the position in the upper surface of the substrate W to which light is to be irradiated from the optical head unit 40 is read, and emitted from the optical head unit 40 to that position. The focusing lens 455 is moved so that the light is in focus.

  When the drawing process is completed, the transfer device 70 carries out the processed substrate W (step S5). When the transfer device 70 subsequently carries in the second substrate W of the lot and places it on the stage 10 (YES in step S6), a drawing process is performed on the substrate W (step S4).

  Thereafter, the processes of step S6, step S4, and step S5 are repeated, and the drawing process for each of the plurality of substrates W constituting the lot is successively performed. When the drawing process for all the substrates W constituting the lot is completed (NO in step S6), the series of processes is completed.

<3. Setting process of emitted light quantity>
The process of determining the optimum value of the amount of light emitted from the light source 471 of the position detection unit 47 (step S2 in FIG. 9) will be described in detail.

<3-1. Sample data collection processing>
In the process of determining the optimum value, “sample data collection process” is performed. In the “sample data collection process”, sample data is obtained at each of a plurality of sample acquisition positions P (i) (i = 1, 2,... N) (see FIG. 11) set in the upper surface of the substrate W. This process is acquired and is executed by the control unit 90 controlling the position detection unit 60 and the stage moving mechanism 20.

<A. Overall flow>
The overall flow of the sample data collection process will be described with reference to FIG. FIG. 10 is a diagram showing the flow of the processing.

  In the sample data collection process, the stage moving mechanism 20 moves the stage 10 in accordance with an instruction from the control unit 90, thereby moving the substrate W relative to the position detection unit 60. Specifically, as shown in FIG. 11, first, the stage 10 is moved along the main scanning direction (Y-axis direction), so that the substrate W is relative to the position detection unit 60 along the main scanning direction. (Main scan) (arrow AR11). Subsequently, the stage moving mechanism 20 moves the stage 10 by a predetermined distance along the sub-scanning direction (X-axis direction), thereby making the substrate W relative to the position detection unit 60 along the sub-scanning direction. (Sub-scanning) (arrow AR12). When the sub-scanning is completed, the main scanning is performed again (arrow AR13). Thus, the position detection unit 60 passes through the entire upper surface of the substrate W by repeatedly performing the main scanning and the sub-scanning.

  The control unit 90 always detects the relative positional relationship between the position detection unit 60 and the substrate W by acquiring the measurement value from the stage position measurement unit 30. On the other hand, the control unit 90 sets the coordinates of a plurality of points on the substrate W as “sample acquisition position P (i) (i = 1, 2,..., N (where N is an integer of 2 or more))”. When the sample acquisition position P (i) of the substrate W reaches the lower position of the position detection unit 60 (YES in step S21), an instruction to acquire sample data is given to the position detection unit 60. Note that the sample acquisition positions P (i) (i = 1, 2,..., N) are preferably evenly distributed over the entire upper surface of the substrate W. For example, as illustrated in FIG. A position corresponding to a lattice point of a lattice-like line defined on the substrate W is preferably set as the sample acquisition position P (i).

  When receiving the sample data acquisition instruction from the control unit 90, the position detection unit 60 performs the sample data acquisition process in accordance with the instruction and acquires the sample data (step S22). By performing this processing, the light quantity distribution data of the reflected light reflected at the sample acquisition position P (i) is given any attribute of “effective”, “light quantity is excessive”, and “light quantity is excessive”, and reflection position information, And it is matched with the emitted light quantity and stored in the sample data table T (see FIG. 15). A specific flow of the sample data acquisition process will be described later.

  Subsequently, the control unit 90 adjusts the amount of light emitted from the light source 61 (the amount of emitted light) based on the sample data acquired in step S22 (step S23). Specifically, when the attribute given to the light amount distribution data acquired as sample data in step S22 is “valid”, the emitted light amount is left as it is (not changed). On the other hand, when the assigned attribute is “light quantity too low”, the emitted light quantity is changed by a predetermined width (hereinafter referred to as “step width”) ΔL larger than the current set value. Further, when the assigned attribute is “excessive light amount”, the emitted light amount is changed to a value smaller by the step width ΔL than the current set value.

  When the process of step S23 ends, the sample data acquisition process is performed again after waiting for the next sample acquisition position P (i + 1) to be reached. At the next sample acquisition position P (i + 1), sample data acquisition processing is performed with the amount of emitted light adjusted based on the sample data acquired at the previous sample acquisition position P (i).

  When scanning of the entire upper surface of the substrate W is completed (specifically, when the position detection unit 60 has passed through the entire upper surface of the substrate W) (YES in step S24), the sample data collection process ends.

  As described above, in the sample data collection process, while changing the amount of emitted light from the light source 61, different positions on the upper surface of the substrate W (specifically, a plurality of sample acquisition positions P ( By irradiating light i) (each of i = 1, 2,... N), a plurality of sample data is acquired.

<B. Sample data acquisition processing>
The sample data acquisition process (step S22 in FIG. 10) will be described with reference to FIG. FIG. 12 is a diagram showing the flow of the processing.

  When the sample data acquisition instruction is issued, the control unit 90 causes the light source 61 to emit light at a predetermined interval a plurality of times (for example, five times) with the set amount of emitted light (step S221). Since the stage 10 continues to move while light is emitted from the light source 61, each light emitted from the light source 61 is slightly different from the upper surface of the substrate W (that is, from the sample acquisition position P (i)). Each position is slightly shifted), but this position shift is so small that it can be ignored in the sample data acquisition process, and each light can be considered to be incident on the same position.

  The light emitted one after another from the light source 61 is reflected at the sample acquisition position P (i), and is sequentially received by the light receiving unit 62. That is, the light receiving unit 62 sequentially acquires light quantity distribution data of a plurality of reflected lights respectively reflected at the sample acquisition position P (i) (step S222). However, at this time, the control unit 90 lengthens the light capturing time in the light receiving unit 62 stepwise. As a result, the amount of light received by the light receiving unit 62 changes stepwise. Then, in the light receiving unit 62, as illustrated in FIG. 13, a group of light amount distribution data D10 (D1, D2,... D5) that change in stages is acquired.

  In the process of step S222, the control unit 90 arranges the light quantity distribution data D1, D2,... D5 acquired one after another and acquires sample data (step S223). Specifically, one light quantity distribution data is selected from the plurality of light quantity distribution data acquired in step S222 and stored as sample data.

<C. Arrangement of light intensity distribution data>
The process of step S223 will be described in detail with reference to FIG. FIG. 14 is a diagram showing the flow of the processing.

  First, the control unit 90 reads the first acquired light amount distribution data D1 from the group of light amount distribution data D10 acquired in step S222 (step S2231), and the read light amount distribution data D1 is “effective data”. Is determined (step S2232).

  Here, “effective data” is light amount distribution data in which the amount of received light is within an allowable range and gives an accurate peak position within an error range of several percent. According to the inventor of the present invention, an effective detected light amount is obtained from an area where the calculated center of gravity is not “0” and is shorter than a predetermined length (specifically, about 100 micrometers) on the upper surface of the substrate W. It has been found that the obtained light quantity distribution data gives an accurate peak position within an error range of about 1%. Therefore, here, the light quantity distribution data in which the center of gravity is not “0” and the number of adjacently appearing pixels having an effective detected light quantity (hereinafter referred to as “pixel width”) is smaller than a predetermined value is effective. Judge as data. For example, when one pixel corresponds to 3 micrometers in terms of the distance in the plane of the substrate W, the predetermined value can be set to “33 (≈100 / 3)”. If the influence of noise is taken into consideration, it is preferable that a pixel having an accumulated voltage of, for example, 10 or more is a pixel that obtains an effective detected light amount.

  Note that data that does not give an accurate center of gravity because the amount of received light is larger than the allowable range, specifically, light amount distribution data that has a pixel width equal to or greater than a predetermined value is hereinafter referred to as “light excess data”. For example, in the case of light amount distribution data that has a large received light amount and spreads out (for example, the light amount distribution data D5 in FIG. 13), the pixel width becomes larger than a predetermined value. That is, such light quantity distribution data is determined as excessive light quantity data.

  On the other hand, data that does not give an accurate center of gravity because the amount of received light is smaller than the allowable range, specifically, light amount distribution data having a center of gravity of “0” is hereinafter referred to as “light amount under-data”. For example, when the pixel having a small amount of received light and obtaining an effective detected light amount is “0”, the center of gravity given by the light amount distribution data is “0”. That is, such light quantity distribution data is determined as light quantity under-data.

  When it is determined that the first acquired light quantity distribution data D1 is valid data (YES in step S2232), the control unit 90 gives the “effective” attribute to the light quantity distribution data D1, and the light quantity distribution data. D1 is stored as sample data (step S2233). Specifically, the controller 90 uses the light quantity distribution data D1 as its attribute information, its reflection position information (the reflection position of the reflected light in the upper surface of the substrate W according to the light quantity distribution data D1), and its emission. The amount of light is stored in association with the amount of light (the amount of light emitted from the light source 61 when the light amount distribution data D1 is given). The sample data is managed in the form of a table, for example. FIG. 15 schematically shows a configuration example of a table (sample data table T) for storing sample data.

  On the other hand, when it is determined that the first acquired light quantity distribution data D1 is not valid data (NO in step S2232), the control unit 90 returns to the process of step S2231 again, and the second acquired light quantity distribution data D2 is obtained. Is read (step S2231), and it is determined whether or not the read light quantity distribution data D2 is “valid data” (step S2232).

  That is, the control unit 90 repeats the processing loop of step S2231, step S2232, and step S2234 until valid data is acquired.

  Of the light quantity distribution data group D10 acquired in the process of step S222, when the last acquired light quantity distribution data D5 is not valid data (that is, all of the light quantity distribution data D1, D2, included in the light quantity distribution data group D10). .., D5 is not valid data (YES in step S2234), the control unit 90 finally selects the light quantity distribution data D1, D2, ..., D5 included in the light quantity distribution data group D10. The acquired light amount distribution data D5 (that is, the light amount distribution data D5 having the largest received light amount among the plurality of light amount distribution data D1, D2,..., D5 acquired in step S222) is the excessive light amount data, the light amount. It is determined whether the data is too small (step S2235).

  And the attribute according to the judgment result of step S2235 is given to the light quantity distribution data D5 acquired last, and the said light quantity distribution data D5 is memorize | stored as sample data (step S2236). That is, when it is determined that the last acquired light quantity distribution data D5 is excessive light quantity data, the control unit 90 gives an attribute of “excessive light quantity” to the light quantity distribution data D5 and samples the light quantity distribution data D5. Store as data. When determining that the light quantity distribution data D5 acquired last is the light quantity under-data, the control unit 90 gives the light quantity distribution data D5 an attribute of “light quantity under-light” and samples the light quantity distribution data D5. Store as data. Specifically, the light quantity distribution data D5 is stored in the sample data table T in association with the attribute information, the reflection position information, and the emitted light quantity.

  That is, in the process of step S223, if the light quantity distribution data group D10 acquired in the process of step S222 includes the light quantity distribution data to be effective data, the light quantity distribution data is acquired as sample data, and the effective data If the light quantity distribution data to be obtained is not included, the light quantity distribution data acquired last is acquired as sample data.

<D. Excellent value>
By the way, in order to increase the detection accuracy in the position detection unit 47, it is important to obtain as much light amount distribution data as “effective data” in the light receiving unit 472 as possible. It is also important to reduce the light amount distribution data as much as possible. This is because, as described above, the light intensity distribution data set as “light intensity under-data” has a center of gravity of “0” and greatly deteriorates the detection accuracy of the height position. Although the accuracy of the light distribution data that is regarded as “excessive light data” is not good, it is possible to calculate the center of gravity for a while. Not as big as the data. That is, the ideal value of the amount of emitted light has a large number of acquisitions of light amount distribution data to be `` effective data '' when light amount distribution data is acquired at an arbitrary position in the upper surface of the substrate W with the amount of emitted light. In addition, the number of acquired light quantity distribution data to be “light quantity under-data” is reduced.

  In the sample data collection process described above, sample data is acquired at different positions in the upper surface of the substrate W under different amounts of emitted light, and each sample data acquired in one sample data collection process is emitted. Of the amounts of light, the value closest to the ideal amount of emitted light is the maximum amount of emitted light that gave valid sample data. Therefore, when one sample data collection process is completed, the control unit 90 stores the maximum emitted light amount to which valid sample data is given as the “excellent value” in the sample data collection process.

<3-2. Evaluation of sample data collection process>
As described above, when the sample data collection process is performed once, a plurality of sample acquisition positions P (i) (i = 1, 2,... N) set in the upper surface of the substrate W (see FIG. 11). In this case, one light quantity distribution data is acquired as sample data. Each sample data is assigned with an attribute (any attribute of “valid”, “low light amount”, “excess light amount”) and stored in association with the reflection position and the emitted light amount (FIG. 15). reference). In the following, sample data whose attribute is “valid” is “effective sample data”, sample data whose attribute is “low light quantity” is “low light quantity sample data”, and whose attribute is “excessive light quantity”. The sampled data is referred to as “excessive light quantity sample data”.

  When the sample data collection process ends, the control unit 90 evaluates the sample data collection process. This process will be described with reference to FIG. FIG. 16 is a diagram showing the flow of the processing.

  The evaluation of the sample data collection process is performed based on all or a part of the plurality of sample data acquired by one sample data collection process (for example, sample data acquired in the second half). Here, for example, it is assumed that the sample data collection process is evaluated based on the sample data acquired in the latter half of the plurality of sample data acquired in one sample data collection process.

  First, the control unit 90 reads sample data acquired in the latter half of the plurality of sample data acquired in one sample data collection process as a “sample data group” (step S31).

  Subsequently, the presence / absence of a hardware abnormality is examined based on the read sample data group (step S32). Specifically, if all the sample data included in the sample data group is under-light sample data, or if all the sample data included in the sample data group is over-light sample data, a hardware error Judge.

  On the other hand, if no hardware abnormality is detected (NO in step S32), the control unit 90 subsequently evaluates the sample data collection process based on the “invalid data continuous number N1” in the sample data group (step S33). However, the “invalid position consecutive number N1” refers to the number of consecutive data having a center of gravity of “0” at the sample acquisition positions P (i) adjacent to each other. The control unit 90 identifies the invalid data continuity number N1 in the sample data group, and when the identified invalid data continuity number N1 is greater than a predetermined value (for example, “10”), performs negative evaluation on the sample data collection process. (Step S36).

  When a positive evaluation is obtained in step S33 (that is, when the invalid data continuous number N1 is equal to or smaller than a predetermined value), the control unit 90 subsequently performs a sample based on the “excess light quantity ratio N2” in the sample data group. The data collection process is evaluated (step S34). However, the “excess light quantity ratio N2” is the ratio of the excessive light quantity sample data to the entire sample data group. The control unit 90 specifies the excess light amount ratio N2 in the sample data group, and gives a negative evaluation to the sample data collection process when the specified excess light amount ratio N2 is larger than a predetermined value (for example, “5%”). (Step S36).

  When an affirmative evaluation is obtained in step S34 (that is, when the excess light amount ratio N2 is equal to or less than a predetermined value), the control unit 90 continues with the sample data based on the “normal detection rate N3” in the sample data group. The collection process is evaluated (step S35). However, the normal detection rate N3 is the ratio of valid sample data to the entire sample data group. The control unit 90 specifies the normal detection rate N3 in the sample data group, and gives a negative evaluation to the sample data collection process when the specified normal detection rate N3 is smaller than a predetermined value (for example, “95%”). (Step S36).

  When a positive evaluation is obtained in step S35 (that is, when the normal detection rate N3 is equal to or less than a predetermined value), the control unit 90 gives a positive evaluation to the sample data collection process (step S37).

  That is, the control unit 90 has the number of consecutive invalid data N1 in the sample data group equal to or less than a predetermined value, the excess light amount ratio N2 in the sample data group is equal to or less than the predetermined value, and the normal detection rate N3 in the sample data group. Gives a positive evaluation to the sample data collection process. It should be noted that each value serving as an evaluation threshold can be arbitrarily set by the operator.

  In the sample data collection process, if the number of consecutive excessive light quantity sample data (or excessive light quantity sample data) is large, or if the excessive light quantity sample data occupies a large percentage, or the percentage of valid sample data being acquired Is small, the sample data collection process is a process with low reliability, and it can be determined that the excellent value obtained therefrom is also low in reliability. That is, by evaluating the entire sample data collection process, it is possible to determine whether or not the excellent value acquired based on the sample data collection process is a reliable value.

<3-3. Overall flow of processing to set the amount of emitted light>
In the process for determining the optimum value of the amount of emitted light (step S2 in FIG. 9), the above-described sample data collection process (and the process for evaluating the sample data collection process) is performed a predetermined number of times (for example, twice). After being repeated, the optimum value is determined.

  The overall flow of the process for determining the optimum value will be described with reference to FIG. FIG. 17 is a diagram showing the flow of the processing.

  When the sample data collection process ends (step S41), the control unit 90 acquires an excellent value in the sample data collection process (step S42), and further evaluates the sample data collection process (step S43). Although not shown, when a hardware abnormality is detected in the process of step S43 (YES in step S32 of FIG. 16), the control unit 90 issues an operation stop instruction. In this case, when the sample data collection process performed at that time is completed, the process for determining the optimum value of the emitted light quantity is stopped even if the sample data collection process is not performed a predetermined number of times.

  When the processes in steps S41 to S43 are completed, the control unit 90 subsequently determines whether or not a predetermined number of sample data collection processes have been completed (step S44).

  If the predetermined number of sample data collection processes have not been completed (NO in step S44), the control unit 90 sets the excellent value acquired in step S42 to the initial value of the light source 61 and the step size ΔL. Is reset to a smaller value (step S45), and the sample data collection process is performed again (step S41).

  Therefore, for example, in the n-th sample data collection process, the amount of emitted light is changed with a smaller step size ΔL, with the excellent value acquired in the (n−1) -th sample data collection process as an initial value. become. For this reason, the superior value acquired in the n-th sample data collection process can be closer to the ideal output light amount value than the superior value in the (n−1) -th sample data collection process. High nature. That is, as the sample data collection process is repeated, there is a high possibility that the superior value approaches the ideal value of the emitted light amount. Note that the number of times of repeating the sample data collection process can be arbitrarily set by the operator.

  When the predetermined number of sample data collection processes are completed (YES in step S44), the control unit 90 acquires the excellent value in the sample data collection process executed last as the optimum value of the emitted light amount (step S46).

  Subsequently, the control unit 90 evaluates the optimum value acquired in step S46 (step S47). Specifically, when all of the sample data collection processes repeatedly executed have received a positive evaluation, a positive evaluation is given to the optimum value acquired in step S46. Here, when a negative evaluation is given to the optimum value acquired in step S46, the control unit 90 performs predetermined error processing (for example, error display) on the assumption that the optimum value of the emitted light amount cannot be determined. To finish the process. On the other hand, when process evaluation is given to the optimum value acquired in step S46, the control unit 90 outputs the optimum value. Specifically, for example, it is displayed on the display screen. That is, only when a positive evaluation is given in step S47, the optimum value acquired in step S46 can be adopted as the amount of light emitted from the light source 61.

<4. Functional block>
Here, each function realized in the drawing apparatus 100 is organized with reference to FIG. FIG. 18 is a block diagram illustrating each function realized in the drawing apparatus 100.

  As becomes clear from the above description, the control unit 90 controls the position detection unit 60 and the stage moving mechanism 20 to execute the sample data collection process. Specifically, the control unit 90 controls the stage moving mechanism 20 to move the substrate W relative to the light source 61 and changes the amount of emitted light from the light source 61 to the upper surface of the substrate W. While intermittently irradiating light and causing the light receiving unit 62 to acquire light quantity distribution data of the reflected light, different positions within the upper surface of the substrate W (sample acquisition positions P (i) (i = 1, 2,... The light amount distribution data of the reflected light reflected in each of N) is successively acquired as sample data. That is, the function as the data collection unit 911 is realized in the control unit 90.

  As described above, in the sample data collection process, the data collection unit 911 adjusts the amount of light emitted from the light source 61 when acquiring the next sample data based on the previously acquired sample data. Specifically, when the previously acquired sample data is valid data, the emitted light amount is not changed, and when the previously acquired sample data is excessive light amount data, the emitted light amount is changed small, When the previously acquired sample data is data with insufficient light amount, the emitted light amount is greatly changed.

  In addition, the data collection unit 911 repeatedly performs the sample data collection process a plurality of times. At this time, the excellent value acquired based on the sample data collection process executed first is set as the initial value of the light source 61 in the sample data collection process executed next. Further, the step width ΔL for changing the amount of light emitted from the light source 61 in the sample data collection process is set to a value smaller than that of the sample data collection process executed previously.

  In addition, the control unit 90 extracts, as effective data, a plurality of sample data acquired by the data collection unit 911 and having the received light amount within an allowable range, and the maximum emitted light amount given the effective data is determined as the output light amount. Get as the optimal value. That is, the control unit 90 has a function as the optimum value acquisition unit 912.

  Further, the control unit 90 is based on a plurality of sample data based on the sample data group composed of all or part of the plurality of sample data acquired by the data collection unit 911 performing the sample data collection process. The optimum value obtained is evaluated. That is, the function as the evaluation unit 913 is realized in the control unit 90.

  In the sample data group, the evaluation unit 913 has a case where the invalid data continuous number N1 is larger than a predetermined number, an excessive light amount ratio N2 is larger than a predetermined value, or a normal detection rate N3 is smaller than a predetermined value. The negative evaluation is given to the sample data collection process (and the optimum value acquired based on the sample data collection process).

<5. Effect>
According to the above embodiment, sample data collection processing is performed to acquire a plurality of sample data, and among the acquired plurality of sample data, the maximum emitted light amount to which valid data is given is acquired as an optimum value. As described above, the optimum value here is close to the ideal value of the amount of emitted light, and by using this value, the position of the upper surface of the substrate W can be detected with high accuracy. That is, according to this configuration, it is possible to easily determine an appropriate amount of emitted light corresponding to the surface state of the substrate W.

  In the above embodiment, the amount of emitted light is changed in accordance with the attribute of the sample data acquired in the sample data collection process. Therefore, it is highly possible that a lot of effective data can be acquired as sample data. Become. Therefore, it is possible to efficiently determine an appropriate amount of emitted light corresponding to the surface state of the substrate W.

  Further, according to the above-described embodiment, based on the sample data group composed of all or part of the plurality of sample data acquired in the sample data collection process, the sample data collection process (as a result, the sample data (Optimum value acquired from the collection process) is evaluated, so that the optimum value can be detected when it is acquired based on an inappropriate sample data collection process. Therefore, it is possible to avoid a risk that an optimum value with low reliability is set as the amount of emitted light as it is.

  Further, according to the above-described embodiment, the sample data collection process is repeated by setting the excellent value acquired in the previously executed data collection process as the initial value of the light source. According to this configuration, as the number of execution times of the sample data collection process is increased, the possibility that more effective data can be acquired increases. As a result, an optimum value close to the ideal value can be acquired. Further, since the step size for changing the amount of emitted light in the sample data collection process is reduced as the number of repetitions of the sample data collection process is increased, an optimum value closer to the ideal value can be acquired.

<6. Modification>
<6-1. Autofocus>
In executing autofocus, the position detection unit 60 may detect the height position of the upper surface of the substrate W in the following manner.

  When the substrate W placed on the stage 10 moves and the area to be detected on the substrate W reaches below the position detection unit 60, the control unit 90 keeps a constant amount of light emitted from the light source 471. Light is emitted multiple times at intervals with the set amount of emitted light. Since the stage 10 continues to move while the light is emitted from the light source 471, each light emitted from the light source 471 enters a slightly different position in the upper surface of the substrate W. The deviation is small enough to be ignored in autofocus.

  The light emitted one after another from the light source 471 is reflected by the upper surface of the substrate W, and is sequentially received by the light receiving unit 472. That is, in the light receiving unit 472, light quantity distribution data of a plurality of reflected lights respectively reflected at substantially the same position in the upper surface of the substrate W are acquired one after another. However, at this time, the control unit 90 changes the light capturing time in the light receiving unit 472 stepwise (for example, lengthens stepwise). As a result, the amount of light received by the light receiving unit 472 changes stepwise. Then, the light receiving unit 472 acquires a light amount distribution data group that changes stepwise.

  Subsequently, the control unit 90 selects one light amount distribution data having a maximum light reception amount within a predetermined range from the acquired plurality of light amount distribution data, and calculates the center of gravity using the selected light amount distribution data. To do.

  As described above, in the drawing apparatus 100, the amount of light emitted from the light source 471 in the position detection unit 47 is set to an appropriate value with respect to the surface state of the substrate W. If the set amount of emitted light is used, position detection is performed. In the unit 47, appropriate light quantity distribution data can be obtained with high possibility, but if the above modification is applied, the possibility of obtaining appropriate light quantity distribution data can be further increased.

<6-2. Database of optimum values>
In the above embodiment, when the processing of the substrate W related to a new lot is started, the processing for determining the optimum value of the emitted light quantity of the light source 61 of the position detection unit 60 is performed. Here, the optimum value acquired in the processing is information indicating the surface state of the substrate W (for example, surface material, type of photosensitive material applied to the surface, thickness of photosensitive material applied to the surface, etc. ) To be accumulated in the storage unit.

  In this case, when the processing of the substrate W related to the new lot is started, if the surface state of the substrate W related to the lot is known, the optimum value stored in association with the surface state is used. The amount of emitted light can be set. In this case, when starting the processing of the substrate W related to the lot, it is not necessary to perform a series of processing for determining the optimum value of the emitted light quantity. That is, the process for determining the optimum value of the amount of emitted light only needs to be performed when the process for the substrate W having an unknown surface state is started.

<6-3. Autofocus with alignment unit 50>
In the above embodiment, the alignment unit 50 may be configured to perform autofocus when imaging the alignment mark.

  In this modification, the drawing apparatus 100 includes a drive unit that adjusts the position of the objective lens 52 in addition to the above configuration. The drive unit linearly moves the objective lens 52 along the Z-axis direction to thereby position the objective lens 52 along the normal direction of the upper surface of the substrate W (that is, between the upper surface of the substrate W and the objective lens 52). The separation distance is changed. As the drive unit, for example, a linear motion mechanism having a rotary motor, a ball screw arranged in parallel with the Z-axis direction, and a nut unit fixed to the support base of the objective lens 52 can be employed. By this drive unit and the position detection unit 60, a functional unit (autofocus unit) that performs autofocus of the alignment unit 50 is realized.

  Specifically, the control unit 90 irradiates light from the light source 61 of the position detection unit 60 with the amount of emitted light set in step S3. The emitted light is reflected by the upper surface of the substrate W, and the reflected light is received by the light receiving unit 62. The control unit 90 detects the height position of the upper surface (specifically, the reflection position) of the substrate W based on the light amount distribution data of the reflected light acquired by the light receiving unit 62, and reflects the acquired height position information. It is stored in association with the position information. On the other hand, the control unit 90 adjusts the position of the objective lens 52 by controlling the drive unit of the objective lens 52 to perform focusing.

<6-4. Other variations>
In the above embodiment, the process of determining the optimum value of the emitted light quantity is performed using the position detection unit 60, but may be performed using the position detection unit 47 provided in the optical head unit 40. .

  In the above embodiment, a diffraction grating type spatial modulator is used as the spatial light modulator 441. However, the configuration of the spatial light modulator 441 is not limited to this. For example, a DMD (Digital Micromirror Device) may be used.

  In the above embodiment, the substrate W to be processed is a semiconductor substrate, but other various substrates (for example, a printed circuit board, a substrate for a color filter provided in a liquid crystal display device, a liquid crystal display). A flat panel display (FPD) glass substrate such as a display device or a plasma display device) may be a processing target.

DESCRIPTION OF SYMBOLS 40 Optical head part 47 Position detection unit 60 Position detection unit 61 Light source 62 Light receiving part 90 Control part 100 Drawing apparatus W board | substrate

Claims (13)

In detecting the position of the target surface by irradiating the target surface with light from the detection light source and detecting the reflected light, the light amount determination device determines the amount of light emitted from the detection light source,
A light source that emits light toward the target surface;
A light receiving unit that receives light reflected from the target surface of the light emitted from the light source and obtains light amount distribution data of the reflected light; and
A transport unit that relatively moves the light source and the target surface;
While intermittently irradiating light from the light source to the target surface that moves relative to the light source while changing the amount of emitted light, the light receiving unit acquires the light amount distribution data of the reflected light. A data collection unit that sequentially acquires, as sample data, light amount distribution data of reflected light reflected at different positions in the target surface;
Among the plurality of sample data acquired by the data collection unit, the data having a received light amount within an allowable range is extracted as effective data, and the maximum emitted light amount given the effective data is calculated as the emitted light amount of the detection light source. An optimal value acquisition unit that acquires the optimal value;
A light quantity determination device comprising: The light quantity determination device according to claim 1,
The data collection unit
If the previously acquired sample data is the effective data, without changing the amount of light emitted from the light source,
When the previously acquired sample data is excessive light amount data in which the amount of received light is larger than the allowable range, the emitted light amount of the light source is changed small,
A light amount determination device that greatly changes the emitted light amount of the light source when the previously acquired sample data is light amount under-data whose light reception amount is smaller than the allowable range. The light quantity determination device according to claim 2,
When the sample data is light amount distribution data that obtains an effective detected light amount from a region corresponding to a predetermined length or more on the target surface, light amount determination for determining the sample data as the excessive light amount data apparatus. It is the light quantity determination apparatus of Claim 2 or 3,
A light amount determination device that determines that the sample data is the light amount under-data when the sample data is light amount distribution data that gives 0 as the center of gravity. The light quantity determination device according to any one of claims 1 to 4,
An evaluation unit that evaluates the optimum value obtained based on the plurality of sample data based on a sample data group composed of all or part of the plurality of sample data acquired by the data collection unit,
A light quantity determination device further comprising: The light quantity determination device according to claim 5,
The evaluation unit is
A light quantity determination device that gives a negative evaluation when the number of sample data that is not valid data is continuously acquired in a sample data group that is greater than a predetermined number. It is the light quantity determination apparatus of Claim 5 or 6, Comprising:
The evaluation unit is
A light quantity determination device that gives a negative evaluation when the ratio of sample data that is excessive light quantity data whose light reception amount is larger than the allowable range to a whole sample data group is larger than a predetermined value. The light quantity determination device according to any one of claims 5 to 7,
The evaluation unit is
A light quantity determination device that gives a negative evaluation when the ratio of the effective data to the entire sample data group is smaller than a predetermined value. The light quantity determination device according to any one of claims 1 to 8,
The data collection unit
The data collection process for acquiring the plurality of sample data is repeatedly executed a plurality of times,
Of the plurality of sample data acquired in the previously executed data collection process, the maximum amount of emitted light to which the effective data is given is set as the initial value of the light source in the data collection process to be executed next. A light quantity determination device. The light quantity determination device according to claim 9,
The data collection unit
A light amount determination device that sets a step size for changing the emitted light amount in the data collection processing to a value smaller than the step size in the data collection processing executed previously. A position detection device that detects the position of the target surface by irradiating the target surface with light from a light source for detection and detecting the reflected light,
A light source that emits light toward the target surface;
A light receiving unit that receives light reflected from the target surface of the light emitted from the light source and obtains light amount distribution data of the reflected light; and
A transport unit that relatively moves the light source and the target surface;
While intermittently irradiating light from the light source to the target surface that moves relative to the light source while changing the amount of emitted light, the light receiving unit acquires the light amount distribution data of the reflected light. A data collection unit that sequentially acquires, as sample data, light amount distribution data of reflected light reflected at different positions in the target surface;
Among the plurality of sample data acquired by the data collection unit, the data having a received light amount within an allowable range is extracted as effective data, and the maximum emitted light amount given the effective data is calculated as the emitted light amount of the detection light source. An optimal value acquisition unit that acquires the optimal value;
With
When detecting the position of the target surface, a position detection device that emits light from the detection light source with a light amount defined by the optimum value acquired by the optimum value acquisition unit. A drawing apparatus that draws a pattern on the target surface by irradiating light from the optical head to a target surface that moves relative to the optical head,
A position detector that detects the position of the target surface by irradiating the target surface with light from a light source for detection and detecting the reflected light;
A position adjusting unit that adjusts the position of the optical system of the optical head with respect to the target surface based on the position of the target surface detected by the position detecting unit;
With
The position detection unit is
A light source that emits light toward the target surface;
A light receiving unit that receives light reflected from the target surface of the light emitted from the light source and obtains light amount distribution data of the reflected light; and
A transport unit that relatively moves the light source and the target surface;
While intermittently irradiating light from the light source to the target surface that moves relative to the light source while changing the amount of emitted light, the light receiving unit acquires the light amount distribution data of the reflected light. A data collection unit that sequentially acquires, as sample data, light amount distribution data of reflected light reflected at different positions in the target surface;
Among the plurality of sample data acquired by the data collection unit, the data having a received light amount within an allowable range is extracted as effective data, and the maximum emitted light amount given the effective data is calculated as the emitted light amount of the detection light source. An optimal value acquisition unit that acquires the optimal value;
With
A drawing device that emits light from the detection light source with a light amount defined by the optimum value acquired by the optimum value acquisition unit when detecting the position of the target surface. In detecting the position of the target surface by irradiating the target surface with light from the detection light source and detecting the reflected light, a light amount determination method for determining the amount of light emitted from the detection light source,
a) Light is intermittently emitted from the light source to the target surface moving relative to the light source while changing the amount of emitted light, and the light amount distribution data of the reflected light is acquired by the light receiving unit. A step of sequentially obtaining, as sample data, light quantity distribution data of reflected light reflected at different positions in the target surface;
b) Among the plurality of sample data acquired in the step a), the sampled light whose amount of received light is within an allowable range is extracted as effective data, and the maximum emitted light amount given the effective data is extracted from the detection light source. Obtaining the optimum value of the amount of emitted light;
A method for determining the amount of light.

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