CN110031964B - Drawing device - Google Patents

Abstract

A scanning unit (Un) of a light beam scanning device for one-dimensionally scanning a light beam (LBn) on a substrate (P) is provided with a 1 st cylindrical lens (CY1) having a focusing force in one direction, a Polygon Mirror (PM) for deflecting the light beam (LBn) having passed through the 1 st cylindrical lens (CY1) so as to perform one-dimensional scanning, an f [ theta ] lens system (FT) for projecting the deflected light beam (LBn) in a telecentric state onto the substrate (P), and a 2 nd cylindrical lens (CY2) having a focusing force in one direction and on which the light beam (LBn) having passed through the f [ theta ] lens system (FT) is incident, wherein the 1 st cylindrical lens (CY1) and the 2 nd cylindrical lens (CY2) have a focusing force in directions orthogonal to each other, and the scanning unit (Un) is further provided with a lens system (G10) disposed between the 1 st cylindrical lens (CY1) and the Polygon Mirror (PM).

Description

Drawing device

The present application is a divisional application, and the original application number is 201780027995.2(PCT/JP2017/016274), and the application date is 04/25/2017, entitled "light beam scanning device and drawing device".

Technical Field

The present invention relates to an optical beam scanning device that scans an optical beam in a main scanning direction in one dimension in order to draw a specific pattern on a substrate, and a drawing device that draws a specific pattern using the optical beam scanning device.

Background

It is known that a light beam projected onto a photosensitive material can be scanned at a constant speed by using an f θ lens system and a polygon mirror (rotating polygon mirror). Each reflection surface of a general polygon mirror is formed in parallel with a direction orthogonal to a rotation surface (a plane including a rotation direction) of the polygon mirror, but an actual reflection surface is accompanied by an error such as a slight inclination with respect to a direction orthogonal to the rotation surface of the polygon mirror, that is, a so-called plane inclination (tilt) error. The error varies for each reflecting surface, and the image position of the spot (projection position of the light beam) formed on the photosensitive material by the f θ lens system is shifted for each reflecting surface.

In order to prevent the deviation of the projection position, in japanese patent laid-open No. 8-297255, a cylindrical lens having a refractive power only in a direction orthogonal to the deflection direction (scanning direction, rotational direction of the polygon mirror) of the polygon mirror is arranged in front of the polygon mirror and behind the f θ lens system 2. That is, 2 cylindrical lenses having generatrices parallel to the scanning direction of the light beam are arranged. Accordingly, the projection position of the light beam on the photosensitive material can be fixed in the sub-scanning direction even if the surface slope error varies depending on the reflection surface of the polygon mirror.

However, as described in japanese patent application laid-open No. 8-297255, when the 1 st cylindrical lens disposed in front of the polygon mirror and the 2 nd cylindrical lens disposed after the f θ lens system (composed of a plurality of spherical lenses) are each composed of a single lens and the generatrix of the 1 st cylindrical lens is made parallel to the generatrix of the 2 nd cylindrical lens, there is a problem that it is difficult to perform optical design (aberration correction) for favorably reducing aberrations (for example, spherical aberration of a light flux) generated by the cylindrical lenses.

Disclosure of Invention

A light beam scanning device according to embodiment 1 of the present invention is a light beam scanning device that scans a light beam one-dimensionally on an object to be irradiated while projecting the light beam from a light source device onto the object to be irradiated, the light beam scanning device including: a 1 st optical member that condenses the light flux in a 1 st direction corresponding to the one-dimensional direction; a beam deflecting unit for receiving the beam passing through the 1 st optical unit and deflecting the beam in the 1 st direction for the one-dimensional scanning; a scanning optical system for causing the light beam deflected by the light beam deflecting member to be incident thereon and projecting the light beam onto the irradiation object; a 2 nd optical member that receives the light flux passing through the scanning optical system and focuses the light flux in a 2 nd direction orthogonal to the 1 st direction; and a lens system provided between the 1 st optical member and the light flux deflecting member, and condensing the light flux passing through the 1 st optical member in the 2 nd direction at a position of the light flux deflecting member.

A drawing device according to embodiment 2 of the present invention is a drawing device that draws a pattern on an irradiation target by moving the irradiation target and a light beam relative to each other in a sub-scanning direction while scanning the irradiation target with the light beam from a light source device in a main scanning direction, the drawing device including: a movable deflecting member for scanning the light beam in the main scanning direction, and deflecting the light beam in the main scanning direction in one dimension; a scanning optical system for causing the light beam one-dimensionally deflected by the movable deflecting member to be incident thereon and condensing and projecting the light beam onto the irradiation target; a 1 st optical member having anisotropic refractive power and converging the light flux toward the movable deflecting member in the main scanning direction; a 2 nd optical member having an anisotropic refractive power and converging the light flux emitted from the scanning optical system toward the irradiation object in the sub-scanning direction; and a 3 rd optical member which is provided between the 1 st optical member and the movable deflecting member, and has an isotropic refractive power for allowing the light beam converging in the main scanning direction to enter, converting the light beam into a light beam converging in the sub scanning direction, and allowing the light beam to exit toward the movable deflecting member.

A drawing device according to embodiment 3 of the present invention is a drawing device for performing one-dimensional scanning in the 1 st direction on an object to be irradiated while projecting a light beam deflected in the 1 st direction by a movable deflecting member onto the object to be irradiated by a scanning optical system, so as to draw a pattern on the object to be irradiated, the drawing device including: a 1 st adjusting optical system including a 1 st lens element having an anisotropic refractive power for converging the light flux projected onto the movable deflecting element in a 2 nd direction orthogonal to the 1 st direction; and a 2 nd adjustment optical system including a 2 nd lens component, the 2 nd lens component having a lens for directing the light from the scanning optical system to the irradiated objectThe anisotropic refractive power with which the light beam converges in the 2 nd direction; setting the wavelength of the light beam as lambda, and setting the numerical aperture of the light beam projected to the irradiated object in the 1 st direction as NA_yThe numerical aperture in the 2 nd direction is defined as NA_xWherein S is a spherical aberration of the light beam in the 1 st direction projected onto the irradiation object₁The spherical aberration in the 2 nd direction is S₂In the above-described optical lens system, the 1 st lens component and the 2 nd lens component are set so as to satisfy either of the following two conditions: s ₁＜λ/NA_y ²And S₂＜λ/NA_x ²And | S₁－S₂|＜λ/NA_y ²And | S₁－S₂|＜λ/NA_x ²。

A drawing device according to embodiment 4 of the present invention is a drawing device that draws a pattern on an irradiation target by scanning a light beam for drawing the pattern one-dimensionally in a main scanning direction on the irradiation target and relatively moving the irradiation target and the light beam in a sub-scanning direction intersecting the main scanning direction, the drawing device including: a light beam generating device for generating the light beam; a beam expander that converts the light beam from the light beam generator into a parallel light beam having an enlarged beam diameter; a beam deflecting means for deflecting the beam converted by the beam expander in one dimension in a direction corresponding to the main scanning direction after the beam is incident; a scanning optical system configured to cause the one-dimensionally deflected light beam to enter and condense a light spot of the light beam on the irradiation target; a 1 st optical system including a 1 st optical element, the 1 st optical element being disposed between the beam expander and the beam deflecting member, and having an anisotropic refractive power for allowing the beam converted by the beam expander to enter and converging the beam projected onto the beam deflecting member in a direction corresponding to the sub-scanning direction; a 2 nd optical system including a 2 nd optical element, the 2 nd optical element having an anisotropic refractive power for converging the light flux emitted from the scanning optical system toward the irradiation object in the sub-scanning direction; and an optical member for deflection provided in an optical path of the beam expander, the optical path of the light beam being deflected in a direction corresponding to the sub-scanning direction.

Drawings

Fig. 1 is a diagram showing a schematic configuration of a device manufacturing system including an exposure apparatus that performs exposure processing on a substrate according to an embodiment.

Fig. 2 is a diagram showing a schematic configuration of the beam switching unit and the drawing head shown in fig. 1, and showing a relationship of arrangement of scanning lines of each scanning unit of the drawing head on the substrate.

Fig. 3 is a diagram showing a specific configuration around the selection optical element and the incidence mirror of the beam switching unit shown in fig. 2.

Fig. 4 is a diagram showing a specific configuration of the scanning unit shown in fig. 2, and is a diagram viewed from a plane (XZ plane) orthogonal to a plane (a plane parallel to the XY plane) including a scanning direction (deflection direction) of the light beam.

Fig. 5 is a schematic view of the light flux from the aperture stop to the substrate shown in fig. 4, as viewed from a plane parallel to a plane including the deflection direction (main scanning direction) of the light flux.

Fig. 6 is a graph showing lens data in the optical design example of comparative example 1.

Fig. 7 is a schematic diagram of a state in which the light beam from the beam expander to the substrate (image plane) in comparative example 1 is observed in a plane parallel to a plane including a deflection direction of the light beam (main scanning direction of the light spot).

Fig. 8 is a schematic view of a state in which the beam expander shown in fig. 7 is viewed from a plane orthogonal to the main scanning direction of the light beam, with respect to the reflection surface of the polygon mirror.

Fig. 9 is a schematic diagram of a state of the light beam from the reflection surface of the polygon mirror to the substrate (image plane) shown in fig. 7 when viewed from a plane orthogonal to the main scanning direction of the light beam.

Fig. 10 is a diagram illustrating an exaggerated state of occurrence of spherical aberration in the main scanning direction of a light beam projected from the f θ lens system to a substrate (image plane).

Fig. 11 is a diagram illustrating an exaggerated state of occurrence of spherical aberration in the sub-scanning direction of a light beam projected from the f θ lens system to a substrate (image plane).

Fig. 12 is a graph obtained by simulating the spherical aberration characteristics in the main scanning direction and the sub-scanning direction of the light beam generated by the optical design example of comparative example 1.

Fig. 13 is a graph showing the spherical aberration characteristics of the difference between the spherical aberration in the main scanning direction and the spherical aberration in the sub-scanning direction in comparative example 1.

Fig. 14 is a graph showing lens data in the optical design example of example 1.

Fig. 15 is a schematic view of a state in which the light flux from the beam expander to the substrate (image plane) in example 1 is observed in a plane parallel to a plane including a deflection direction of the light flux (main scanning direction of the light spot).

Fig. 16 is a schematic view of a state in which the beam expander shown in fig. 15 is viewed on the reflection surface of the polygon mirror in a plane orthogonal to the main scanning direction of the light beam.

Fig. 17 is a schematic view of a state in which the light beams from the reflection surfaces of the polygon mirror to the substrate (image plane) shown in fig. 15 are viewed in a plane orthogonal to the main scanning direction of the light beams.

Fig. 18 is a graph obtained by simulating the spherical aberration characteristics in the main scanning direction and the sub-scanning direction of the light beam generated by the optical design example of example 1.

Fig. 19 is a graph showing the spherical aberration characteristics of the difference between the spherical aberration in the main scanning direction and the spherical aberration in the sub-scanning direction in example 1.

Fig. 20A is a state diagram showing that the parallel plate is not inclined in the XZ plane, and fig. 20B is a state diagram showing that the parallel plate is inclined at an angle η with respect to the YZ plane.

Detailed Description

The optical beam scanning device and the drawing device according to the embodiments of the present invention are disclosed in the preferred embodiments and will be described in detail below with reference to the accompanying drawings. The embodiments of the present invention are not limited to these embodiments, and include embodiments to which various modifications and improvements are added. That is, the constituent elements described below include embodiments that can be easily conceived by the practitioner and are substantially the same, and the constituent elements described below can be appropriately combined. Various omissions, substitutions, and changes in the components can be made without departing from the spirit of the invention.

[ embodiment 1 ]

Fig. 1 is a schematic configuration diagram showing a device manufacturing system 10 including an exposure apparatus EX for performing an exposure process on a substrate (irradiation target) P according to embodiment 1. In the following description, unless otherwise specified, an XYZ rectangular coordinate system in which the direction of gravity is the Z direction is set, and the X direction, the Y direction, and the Z direction are described in accordance with the arrows shown in the drawings.

The device manufacturing system 10 is a system (substrate processing apparatus) that performs a specific process (such as an exposure process) on a substrate P to manufacture an electronic device. The device manufacturing system 10 is a manufacturing system for constructing a production line for manufacturing, for example, a flexible display, a film-shaped touch panel, a film-shaped color filter for a liquid crystal display panel, a flexible wiring, a flexible sensor, or the like, which is an electronic device. Hereinafter, a flexible display will be described as an electronic component on the premise of the flexible display. As the flexible display, for example, an organic EL display, a liquid crystal display, and the like are available. The component manufacturing system 10 has a so-called Roll-To-Roll (Roll To Roll) configuration, that is: the substrate P is fed from a supply roll (not shown) in the figure, on which a flexible sheet-like substrate (sheet substrate) P is wound in a roll shape, and various processes are continuously performed on the fed substrate P, and thereafter, the substrate P after various processes is wound up by a recovery roll (not shown). Therefore, the substrate P after various processes is in a state where a plurality of elements are connected in the conveyance direction of the substrate P, and is a substrate for multi-chamfering. The substrate P sent from the supply roll is subjected to various processes in order by the processing apparatus PR1, the exposure apparatus EX, and the processing apparatus PR2, and is wound up by the recovery roll. The substrate P has a belt-like shape in which the moving direction (transfer direction) of the substrate P is the longitudinal direction (long dimension) and the width direction is the short direction (short dimension).

In embodiment 1, the X direction is a direction in which the substrate P is directed from the supply roller toward the recovery roller in a horizontal plane orthogonal to the Z direction. The Y direction is a direction orthogonal to the X direction in a horizontal plane orthogonal to the Z direction, and is a width direction (short dimension direction) of the substrate P. the-Z direction is set as a direction in which gravity acts (gravity direction), and the conveyance direction of the substrate P is set as the + X direction.

For example, a resin film, a foil (foil) made of a metal such as stainless steel or an alloy, or the like can be used as the substrate P. As the material of the resin film, for example, a material containing at least one of a polyethylene resin, a polypropylene resin, a polyester resin, an ethylene-vinyl ester copolymer resin, a polyvinyl chloride resin, a cellulose resin, a polyamide resin, a polyimide resin, a polycarbonate resin, a polystyrene resin, and a vinyl acetate resin can be used. The thickness and rigidity (young's modulus) of the substrate P may be within a range such that the substrate P does not have creases or irreversible wrinkles due to buckling when passing through the transfer path of the device manufacturing system 10. Films of PET (polyethylene terephthalate) and PEN (polyethylene naphthalate) having a thickness of about 25 to 200 μm are typical of preferable sheet substrates as the base material of the substrate P.

The substrate P is heated in each process performed in the device manufacturing system 10, and therefore, a material having a not large thermal expansion coefficient is preferably selected. For example, the thermal expansion coefficient can be suppressed by mixing an inorganic filler in a resin film. The inorganic filler may be, for example, titanium oxide, zinc oxide, aluminum oxide, silicon oxide, or the like. The substrate P may be a single layer of an extra thin glass having a thickness of about 100 μm manufactured by a float method or the like, or may be a laminate in which the above resin film, foil, or the like is laminated on the extra thin glass.

The flexibility of the substrate P means that the substrate P can be bent without breaking or breaking even when a force of a self weight is applied to the substrate P. The flexibility also includes the property of buckling by a force of a self weight. The degree of flexibility varies depending on the material, size, and thickness of the substrate P, the layer structure formed on the substrate P, and the environment such as temperature and humidity. In short, the flexibility range can be defined as long as the substrate P can be smoothly transported without buckling or breaking (cracking or cracking) when the substrate P is securely wound around various transport direction switching members such as transport rollers and rotary drums provided on the transport path in the device manufacturing system 10 according to embodiment 1.

The processing apparatus (processing apparatus) PR1 performs the processing of the preceding step on the substrate P sent to the exposure apparatus EX while conveying the substrate P sent from the supply roller to the exposure apparatus EX at a specific speed in the conveyance direction (+ X direction) along the longitudinal direction. By the processing in the preceding step, the substrate P sent to the exposure apparatus EX becomes a substrate (photosensitive substrate) having a photosensitive functional layer (photosensitive layer) formed on the surface thereof.

The photosensitive functional layer is applied as a solution onto the substrate P and dried to form a layer (film). Typical examples of the photosensitive functional layer are a photoresist (liquid or dry film), but as a material not requiring development treatment, there are a photosensitive silane coupling agent (SAM) in which the lyophilicity of a portion irradiated with ultraviolet rays is modified, a photosensitive reducing agent in which a plating reducing group is exposed to a portion irradiated with ultraviolet rays, and the like. When a photosensitive silane coupling agent is used as the photosensitive functional layer, the pattern portion exposed to ultraviolet light on the substrate P is modified from lyophilic to lyophilic. Therefore, a pattern layer to be an electrode constituting a Thin Film Transistor (TFT), a semiconductor, and an insulating or connecting wiring can be formed by selectively applying a liquid containing a conductive ink (an ink containing conductive nanoparticles such as silver or copper) or a semiconductor material to a portion having lyophilic properties. In the case of using a photosensitive reducing agent as the photosensitive functional layer, the plating reducing group is exposed on the pattern portion exposed by ultraviolet rays on the substrate P. Therefore, immediately after exposure, the substrate P is immersed in a plating solution containing palladium ions or the like for a fixed time, thereby forming (depositing) a pattern layer made of palladium. Such plating treatment is an additive (additive) process, and may be assumed as an etching treatment in a subtractive (reactive) process. In this case, the substrate P sent to the exposure apparatus EX may be formed by using PET or PEN as a base material, depositing a metal thin film such as aluminum (Al) or copper (Cu) on the entire surface of the base material, or selectively depositing a photoresist layer thereon.

The exposure apparatus (processing apparatus) EX is a processing apparatus that performs exposure processing on the substrate P while conveying the substrate P conveyed from the processing apparatus PR1 to the processing apparatus PR2 in the conveyance direction (+ X direction) at a specific speed. The exposure apparatus EX irradiates a surface of the substrate P (a surface of the photosensitive functional layer, i.e., a photosensitive surface) with a light pattern corresponding to a pattern for an electronic element (e.g., a pattern such as an electrode or a wiring of a TFT constituting the electronic element). Thereby, a latent image (modified portion) corresponding to the pattern is formed on the photosensitive functional layer.

In embodiment 1, the exposure apparatus EX is an exposure apparatus of a direct imaging system, i.e., an exposure apparatus of a so-called raster scan system (writing apparatus) which does not use a mask. The exposure apparatus EX scans (main-scans) a spot SP of a pulse beam LB (pulse beam) for exposure one-dimensionally in a predetermined scanning direction (Y direction) on an irradiated surface (photosensitive surface) of a substrate P while conveying the substrate P in the + X direction (sub-scanning direction), and modulates (turns on/off) the intensity of the spot SP at high speed in accordance with pattern data (drawing data and pattern information). Thereby, a light pattern corresponding to a specific pattern of electronic elements, circuits, wirings, and the like is drawn and exposed on the irradiated surface of the substrate P. That is, the sub-scanning of the substrate P and the main scanning of the spot SP relatively two-dimensionally scan the spot SP on the irradiation surface (surface of the photosensitive functional layer) of the substrate P, and the exposure specific pattern is drawn on the irradiation surface of the substrate P. Since the substrate P is transported in the transport direction (+ X direction), a plurality of exposure regions are provided at a predetermined interval in the longitudinal direction of the substrate P by the exposure apparatus EX. Since the electronic element is formed in the exposure region, the exposure region is also an element formation region.

The processing apparatus (processing apparatus) PR2 performs a subsequent process (for example, plating, development, etching, or the like) on the substrate P exposed by the exposure apparatus EX while conveying the substrate P sent from the exposure apparatus EX to the recovery roller at a predetermined speed in the conveyance direction (+ X direction) along the longitudinal direction. Through the subsequent steps, a pattern layer of elements is formed on the substrate P.

Next, the exposure apparatus EX will be described in further detail with reference to fig. 2 to 5. The exposure apparatus EX is housed in a temperature-controlled room ECV as shown in fig. 1. The temperature controlled chamber ECV keeps the inside at a specific temperature and a specific humidity, thereby suppressing the shape change of the substrate P conveyed inside due to the temperature, and suppressing the moisture absorption of the substrate P, the electrostatic charging generated by the conveyance, and the like. The temperature-controlled room ECV is disposed on the installation surface E of the manufacturing plant via passive or active vibration-resistant units SU1 and SU 2. The anti-vibration units SU1 and SU2 reduce vibration from the installation surface E. The installation surface E may be a floor surface of a factory or a surface on an installation base (pedestal) which is installed on the floor surface in a dedicated manner to produce a horizontal surface. The exposure apparatus EX includes at least a substrate conveyance mechanism 12, a light source device 14, a beam switching unit BDU, a drawing head 16, and a control device 18. The controller 18 controls each part of the exposure apparatus EX. The control device 18 includes a computer, a recording medium on which a program is recorded, and the like, and functions as the control device 18 according to embodiment 1 by the computer executing the program.

The substrate transfer mechanism 12 is a part of a substrate transfer apparatus constituting the device manufacturing system 10, and transfers the substrate P transferred from the processing apparatus PR1 at a predetermined speed in the exposure apparatus EX, and then delivers the substrate P at a predetermined speed to the processing apparatus PR 2. The substrate conveying mechanism 12 includes an edge position controller EPC, a drive roller R1, a tension adjusting roller RT1, a rotary drum (cylindrical drum) DR, a tension adjusting roller RT2, a drive roller R2, and a drive roller R3 in this order from the upstream side (the-X direction side) in the conveying direction of the substrate P. The substrate P is set on the edge position controller EPC, the drive rollers R1 to R3, the tension adjusting rollers RT1 and RT2, and the rotary drum (cylindrical drum) DR of the substrate conveyance mechanism 12, thereby defining a conveyance path of the substrate P conveyed in the exposure apparatus EX.

The edge position controller EPC adjusts the position in the width direction (Y direction and the short-dimension direction of the substrate P) of the substrate P conveyed from the processing apparatus PR 1. That is, the edge position controller EPC adjusts the position of the substrate P in the width direction by moving the substrate P in the width direction so that the position of the end (edge) of the substrate P in the width direction, which is conveyed in a state where a specific tension is applied, is within a range (allowable range) of about ± tens μm to several tens μm from the target position. The edge position controller EPC includes a roller on which the substrate P is mounted in a state in which a specific tension is applied, and an edge sensor (edge detection unit), not shown, that detects the position of an edge (edge) of the substrate P in the width direction. The edge position controller EPC moves the roller of the edge position controller EPC in the Y direction based on the detection signal detected by the edge sensor, and adjusts the position of the substrate P in the width direction. The drive roller (nip roller) R1 rotates while holding both front and back surfaces of the substrate P conveyed from the edge position controller EPC, and conveys the substrate P to the rotary drum DR. Further, the edge position controller EPC may appropriately adjust the position of the substrate P in the width direction so that the longitudinal direction of the substrate P wound around the rotary drum DR is always orthogonal to the central axis AXo of the rotary drum DR, and may appropriately adjust the parallelism between the rotation axis of the drum of the edge position controller EPC and the Y axis so that the inclination error in the traveling direction of the substrate P is corrected.

The rotary drum DR has a central axis AXo extending in the Y direction and extending in a direction intersecting the direction in which gravity acts, and a cylindrical outer peripheral surface having a constant radius from the central axis AXo. The rotary drum DR supports (holds) the substrate P by bending a part of the substrate P in the longitudinal direction into a cylindrical surface along the outer peripheral surface (circumferential surface), and conveys the substrate P in the + X direction (longitudinal direction) while rotating about the central axis AXo. The rotary drum DR is a region (portion) on the substrate P on which the light beam LB (spot SP) from the drawing head 16 is projected, and is supported by the outer peripheral surface thereof. The rotary drum DR supports (holds in close contact with) the substrate P from the side (back surface) opposite to the surface (side surface on which the photosensitive surface) on which the electronic components are formed. On both sides of the rotary drum DR in the Y direction, shafts Sft supported by annular bearings so that the rotary drum DR rotates about the central shaft AXo are provided. The rotary drum DR is rotated at a fixed rotation speed around the central shaft AXo by applying torque to the shaft Sft from a not-shown rotary drive source (e.g., a motor, a speed reduction mechanism, or the like) controlled by the control device 18. For convenience, a plane including the central axis AXo and parallel to the YZ plane is referred to as a central plane Poc.

The driving rollers (nip rollers) R2 and R3 are disposed at a predetermined interval in the conveyance direction (+ X direction) of the substrate P, and provide a predetermined slack (margin) to the substrate P after exposure. The drive rollers R2 and R3 rotate while holding both front and back surfaces of the substrate P, and convey the substrate P to the processing apparatus PR2, similarly to the drive roller R1. The tension adjusting rollers RT1 and RT2 are energized in the-Z direction, and apply a predetermined tension to the substrate P wound around the rotary drum DR and supported in the longitudinal direction. This stabilizes the tension in the longitudinal direction applied to the substrate P wound around the rotary drum DR within a specific range. The controller 18 controls a rotation driving source (e.g., a motor, a speed reduction mechanism, or the like), not shown, to rotate the driving rollers R1 to R3. The rotation axes of the drive rollers R1 to R3 and the rotation axes of the tension adjustment rollers RT1 and RT2 are parallel to the central axis AXo of the rotary drum DR.

The light source device 14 generates and emits a pulsed light beam (pulsed light beam, pulsed light, laser) LB. The light beam LB has a peak wavelength of ultraviolet light in a wavelength band of 370nm or less, and the emission frequency (oscillation frequency, specific frequency) of the light beam LB is Fa. Light beam LB emitted from light source device 14 is incident on drawing head 16 via light beam switching unit BDU. The light source device 14 emits and emits a light beam LB at a light emission frequency Fa in accordance with the control of the control device 18. The light source device 14 may be a fiber amplifier laser light source including a semiconductor laser element for generating a pulse light in an infrared wavelength range, a fiber amplifier, a wavelength conversion element (harmonic generation element) for converting the amplified pulse light in the infrared wavelength range into a pulse light in an ultraviolet wavelength range, and the like. By configuring the light source device 14 in this manner, high-brightness ultraviolet pulsed light having an oscillation frequency Fa of several hundred MHz and a light emission time of 1 pulsed light of several picoseconds or so can be obtained. The light beam LB emitted from the emission window of the light source device 14 is a thin parallel light beam having a beam diameter of about 1mm or less.

The beam switching unit BDU is described in detail below with reference to fig. 2, and includes a plurality of optical switching elements that switch the beam LB so as to be incident on any one of a plurality of scanning units Un (n is 1, 2, …, and 6) constituting the drawing head 16 at a time-sharing basis. The plurality of switching elements sequentially switch the scanning unit Un into which the light beam LB is incident among the scanning units U1-U6. For example, the beam switching unit BDU repeatedly performs the operation of switching the scanning unit Un into which the light beam LB is incident in the order of U1 → U2 → U3 → U4 → U5 → U6. The light beam LB from the light source device 14, which is incident on the scanning unit Un via the light beam switching portion BDU, is sometimes represented as LBn. The light beam LBn incident to the scanning unit U1 may be denoted by LB1, and the light beams LBn incident to the scanning units U2 to U6 may be denoted by LB2 to LB 6.

As shown in fig. 2, the polygon mirror PM for main-scanning the incident light beams LB1 to LB6 is provided in each of the scanning units U1 to U6. In embodiment 1, the polygon mirrors PM of the scanning units Un are synchronously controlled so as to precisely rotate at the same rotational speed while maintaining a fixed rotational angle phase. Thus, the timings of the main scanning of the light beams LB1 to LB6 projected from the scanning units U1 to U6 to the substrate P (main scanning periods of the spot SP) can be set so as not to overlap each other. Therefore, the beam switching unit BDU can switchingly supply the light beam LB to any one of the scanning units Un so that the light beam LB is incident on any one of the scanning units Un that performs scanning of the spot SP, that is, can distribute the light beam LB by time division. Further, the scanning unit Un performing the main scanning of the spot SP (the scanning unit Un on which the light beam LBn is incident) is repeated in the order of U1 → U2 → U3 → U4 → U5 → U6 → U1 …. A configuration for distributing the light beam LB from the light source device 14 to each of the plurality of scanning units Un in a time-sharing manner is disclosed in international publication No. 2015/166910.

As shown in fig. 2, the drawing head 16 is a so-called multi-beam type drawing head in which a plurality of scanning units Un (U1 to U6) having the same configuration are arranged. The drawing head 16 draws a pattern on a part of the substrate P supported by the outer peripheral surface (circumferential surface) of the rotary drum DR by a plurality of scanning units Un (U1 to U6). Each of the scanning units Un (U1 to U6) focuses (condenses) the light beam LBn on the substrate P while projecting the light beam LBn from the beam switching unit BDU onto the substrate P (on the irradiated surface of the substrate P). Thus, the light beam LBn (LB1 to LB6) projected onto the substrate P becomes the spot SP. The spot SP of the light beam LBn (LB1 to LB6) projected onto the substrate P is scanned in the main scanning direction (Y direction) by the rotation of the polygon mirror PM of each scanning unit Un (U1 to U6). By scanning the spot SP, a linear drawing line (scanning line) SLn (n is 1, 2, …, or 6) for drawing a pattern of 1 line is defined on the substrate P. That is, a drawing line SLn indicates a scanning locus of the spot SP of the light beam LBn on the substrate P.

Scanning unit U1 scans spot SP along drawing line SL1, and similarly, scanning units U2 to U6 scan spot SP along drawing lines SL2 to SL 6. As shown in fig. 2, the drawing lines SLn (SL1 to SL6) of the plurality of scanning units Un (U1 to U6) are arranged in 2 rows in the circumferential direction of the rotary drum DR with the center plane Poc (see fig. 1) therebetween, and are offset from each other. The odd-numbered drawing lines SL1, SL3, and SL5 are located on the irradiated surface of the substrate P on the upstream side (on the (-X direction side) in the substrate P conveyance direction with respect to the central plane Poc, and are arranged in 1 line at a specific interval in the Y direction. The even drawing lines SL2, SL4, and SL6 are located on the irradiated surface of the substrate P on the downstream side (+ X direction side) of the center plane Poc in the conveyance direction of the substrate P, and are arranged in 1 line at a specific interval in the Y direction.

Therefore, the plurality of scanning units Un (U1 to U6) are also arranged in a staggered arrangement in 2 rows in the conveyance direction of the substrate P with the center plane Poc in between. That is, the odd-numbered scanning units U1, U3, and U5 are arranged in 1 row at a specific interval in the Y direction on the upstream side (the (-X direction side) in the conveyance direction of the substrate P with respect to the center plane Poc. The even-numbered scanning units U2, U4, and U6 are arranged in 1 row at a specific interval in the Y direction on the downstream side (+ X direction side) of the center plane Poc in the conveyance direction of the substrate P. The odd-numbered scan cells U1, U3, and U5 and the even-numbered scan cells U2, U4, and U6 are disposed symmetrically with respect to the center plane Poc when viewed from the XZ plane.

The odd-numbered drawing lines SL1, SL3, and SL5 and the even-numbered drawing lines SL2, SL4, and SL6 are separated from each other, but are connected without being separated from each other in the Y direction (the width direction of the substrate P and the main scanning direction). The drawing lines SL1 to SL6 are substantially parallel to the width direction of the substrate P, i.e., the central axis AXo of the rotary drum DR. The drawing line SLn is continued in the Y direction, and the ends of the drawing line SLn are adjacent to each other in the Y direction or partially overlap each other. When the end portions of the drawing lines SLn are overlapped with each other, they may be overlapped in a range of several percent or less in the Y direction including the drawing start point or the drawing end point with respect to the length of each drawing line SLn, for example.

In this way, the scanning region is shared by the scanning units Un (U1 to U6) so that the plurality of scanning units Un (U1 to U6) entirely cover the entire width direction of the exposure region. Thus, each of the scanning units Un (U1 to U6) can draw a pattern for each of a plurality of regions (drawing ranges) divided in the width direction of the substrate P. For example, if the Y-direction scanning length (the length of the drawing line SLn) of 1 scan cell Un is set to about 20 to 60mm, 6 scan cells Un are arranged in the Y-direction in total of the 3 odd-numbered scan cells U1, U3, and U5 and the 3 even-numbered scan cells U2, U4, and U6, thereby widening the Y-direction drawing width to about 120 to 360 mm. The lengths (the lengths of the drawing ranges) of the drawing lines SLn (SL1 to SL6) are set to be the same in principle. That is, the scanning distances of the spots SP of the light beam LBn scanned along the respective drawing lines SL1 to SL6 are set to be the same in principle.

In the case of embodiment 1, since the light beam LB from the light source device 14 is a pulsed light, the spot SP projected on the scanning line SLn during the main scanning period is discrete in accordance with the oscillation frequency Fa (for example, 400MHz) of the light beam LB. Therefore, it is necessary to overlap the spot SP projected by the 1 pulse light of the light beam LB and the spot SP projected by the next 1 pulse light in the main scanning direction. The amount of overlap is set in accordance with the size φ of the spot SP, the scanning speed (speed of main scanning) Vs of the spot SP, and the oscillation frequency Fa of the light beam LB. The effective size (diameter) phi of the spot SP is 1/e of the peak intensity of the spot SP when the intensity distribution of the spot SP is approximately Gaussian ²(or 1/2) is determined by the width dimension of the intensity. In the present embodiment 1, the spot SP is set to be equal to the effective size (ruler)Cun) phi is superimposed on phi × 1/2 to set the scanning speed Vs (rotational speed of the polygon mirror PM) and oscillation frequency Fa of the spot SP. Therefore, the projection interval of the pulse-shaped spot SP in the main scanning direction becomes Φ/2. Therefore, in the sub-scanning direction (direction orthogonal to the drawing line SLn), it is preferable that the substrate P be set so as to move by a distance of approximately 1/2 of the effective size Φ of the light spot SP between 1 scan of the light spot SP along the drawing line SLn and the next scan. Further, when the drawing lines SLn adjacent in the Y direction are connected in the main scanning direction, it is preferable that these lines overlap each other by Φ/2. In embodiment 1, the size (dimension) Φ of the spot SP is set to about 3 μm.

Each scanning unit Un (U1 to U6) irradiates each light beam LBn on the substrate P so that each light beam LBn travels toward the central axis AXo of the rotary drum DR on at least the XZ plane. Thus, the optical path (central beam axis) of the light beam LBn traveling from each scanning unit Un (U1 to U6) toward the substrate P is parallel to the normal line of the irradiated surface of the substrate P on the XZ plane. At this time, in the XZ plane, if an angle between the central plane Poc and the traveling direction of the light beam LB projected onto the substrate P from the odd-numbered scanning units U1, U3, and U5 (the direction in which the drawing lines SL1, SL3, and SL5 are connected to the central axis AXo) is set to- θ 1, an angle between the central plane Poc and the traveling direction of the light beam LB projected onto the substrate P from the even-numbered scanning units U2, U4, and U6 (the direction in which the drawing lines SL2, SL4, and SL6 are connected to the central axis AXo) is set to + θ 1. That is, in the XZ plane, the traveling direction of the light beam LB projected onto the substrate P from the odd-numbered scan units U1, U3, and U5 and the traveling direction of the light beam projected onto the substrate P from the even-numbered scan units U2, U4, and U6 are symmetrical with respect to the center plane Poc. Each of the scanning units Un (U1 to U6) irradiates the substrate P with the light flux LBn such that the light flux LBn irradiated to the drawing line SLn (SL1 to SL6) is perpendicular to the irradiated surface of the substrate P in a plane parallel to the YZ plane. That is, the light beam LBn (LB1 to LB6) projected onto the substrate P is scanned in the main scanning direction of the spot SP on the irradiated surface so as to be telecentric.

Further, the configuration of the beam switching unit BDU and the scanning unit Un (U1 to U6) of the drawing head 16 will be briefly described with reference to fig. 2. The beam switching unit BDU includes a plurality of optical elements AOMn for selection (AOM1 to AOM6) as switching elements, a plurality of mirrors M1 to M12, a plurality of incidence mirrors IMn (IM1 to IM6), and an absorber TR. An Acousto-Optic Modulator (AOM) having optical elements for selection AOMn (AOM 1-AOM 6) that are transparent to the light beam LB and driven by an ultrasonic signal. The plurality of optical elements for selection AOMn (AOM1 to AOM6) and the plurality of incidence mirrors IMn (IM1 to IM6) are provided corresponding to the plurality of scanning units Un (U1 to U6). For example, the optical element for selection AOM1 and the incidence mirror IM1 are provided corresponding to the scanning unit U1, and similarly, the optical elements for selection AOM2 to AOM6 and the incidence mirrors IM2 to IM6 are provided corresponding to the scanning units U2 to U6.

The light beam LB is guided from the light source device 14 to the absorber TR in a zigzag path by bending the optical path thereof by the mirrors M1 to M12. Hereinafter, the selective optical elements AOMn (AOM1 to AOM6) are all in an off state (a state where no ultrasonic signal is applied) and will be described in detail. Although not shown in fig. 2, a plurality of lenses are provided in the beam path from the mirror M1 to the absorber TR to converge the beam LB from a parallel beam or to return the converged and diverged beam LB to a parallel beam. The structure will be described below with reference to fig. 3.

In fig. 2, the light beam LB from the light source device 14 travels parallel to the X axis in the-X direction and is incident on the mirror M1. The light beam LB reflected in the mirror M1 in the-Y direction is incident on the mirror M2. The light beam LB reflected in the + X direction by the mirror M2 passes straight through the optical selection element AOM5 and reaches the mirror M3. The light beam LB reflected in the mirror M3 in the-Y direction is incident on the mirror M4. The light beam LB reflected in the-X direction by the mirror M4 passes straight through the optical selection element AOM6 and reaches the mirror M5. The light beam LB reflected in the mirror M5 in the-Y direction is incident on the mirror M6. The light beam LB reflected in the + X direction by the mirror M6 passes straight through the optical selection element AOM3 and reaches the mirror M7. The light beam LB reflected in the mirror M7 in the-Y direction is incident on the mirror M8. The light beam LB reflected in the-X direction by the mirror M8 passes straight through the optical selection element AOM4 and reaches the mirror M9. The light beam LB reflected in the mirror M9 in the-Y direction is incident on the mirror M10. The light beam LB reflected in the + X direction by the mirror M10 passes straight through the optical selection element AOM1 and reaches the mirror M11. The light beam LB reflected in the mirror M11 in the-Y direction is incident on the mirror M12. The light beam LB reflected in the-X direction by the mirror M12 is guided straight through the selective optical element AOM2 to the absorber TR. The absorber TR is a light trap that absorbs the light beam LB to suppress the light beam LB from leaking outside.

When an ultrasonic signal (high-frequency signal) is applied to each optical selection element AOMn, 1-order diffracted light is generated as an output light beam (light beam LBn), the 1-order diffracted light being obtained by diffracting an incident light beam (0-order light) LB at a diffraction angle corresponding to a frequency of a high frequency. Therefore, the light beam emitted as 1-time diffracted light from the optical element for selection AOM1 becomes LB1, and similarly, the light beams emitted as 1-time diffracted light from the optical elements for selection AOM2 to AOM6 become LB2 to LB 6. In this manner, each of the selective optical elements AOMn (AOM1 to AOM6) functions to deflect the optical path of the light beam LB from the light source device 14. However, since the generation efficiency of the 1 st diffracted light of the actual acousto-optic modulator is about 80% of that of the 0 th diffracted light, the intensity of the beam LBn (LB1 to LB6) deflected by each of the selective optical elements AOMn (AOM1 to AOM6) is lower than that of the original beam LB. When any of the selective optical elements AOMn (AOM1 to AOM6) is in an on state, about 20% of 0-time light traveling straight without diffraction remains, but it is finally absorbed by the absorber TR.

Each of the plurality of optical elements for selection AOMn (AOM1 to AOM6) is provided so as to deflect the light beam LBn (LB1 to LB6) which is the deflected 1 st-order diffracted light with respect to the light beam LB to be incident in the-Z direction. The light beams LBn (LB1 to LB6) emitted by deflecting the selection optical elements AOMn (AOM1 to AOM6) are projected onto incidence mirrors IMn (IM1 to IM6) provided at positions distant from the selection optical elements AOMn (AOM1 to AOM6) by a predetermined distance. Each of the incidence mirrors IMn (IM1 to IM6) guides the light beam LBn (LB1 to LB6) to the corresponding scanning unit Un (U1 to U6) by reflecting the incident light beam LBn (LB1 to LB6) in the-Z direction. Each of the incidence mirrors IMn is also called a falling mirror because it causes each of the light beams LBn to fall in the-Z direction.

The optical elements for selection AOMn (AOM 1-AOM 6) may have the same structure, function, action, etc. The plurality of optical elements AOMn for selection (AOM1 to AOM6) are turned on/off according to on/off of a drive signal (high frequency signal) from the control device 18, and thereby generate diffracted light that diffracts the incident light beam LB. For example, the selective optical element AOM5 transmits the incident light beam LB from the light source device 14 without diffracting when it is in the off state without applying a drive signal (high frequency signal) from the control device 18. Therefore, the light beam LB transmitted through the selective optical element AOM5 is incident on the mirror M3. On the other hand, when the selection optical element AOM5 is turned on by a drive signal (high-frequency signal) from the control device 18, the incident light beam LB is diffracted and directed to the incident mirror IM 5. That is, the selection optical element AOM6 is switched by the drive signal. By switching the selection optical elements AOMn in this way, the light beam LBn can be directed to any of the scan cells Un, and the scan cell Un on which the light beam LBn is incident can be switched.

The controller 18 shown in fig. 1 controls on/off of the pulsed light beam LB emitted from the light source device 14 in 1-pulse units based on pattern data (drawing data) corresponding to a pattern to be drawn. A configuration for turning on/off (modulating) the pulsed light beam LB from the light source device 14 based on pattern data when the light source device 14 is set as a fiber amplifier laser light source is also disclosed in the above-mentioned international publication No. 2015/166910. Here, the pattern data will be explained simply. The pattern data (drawing data, design information) is provided for each scanning unit Un, and the pattern drawn by each scanning unit Un is divided into pixels of a size set according to the size of the spot SP, and each of the plurality of pixels is represented by logical information (pixel data) corresponding to the pattern to be drawn. That is, the pattern data is dot map data composed of logical information of a plurality of pixels which are two-dimensionally decomposed such that a direction along the main scanning direction (Y direction) of the spot SP is a column direction and a direction along the sub scanning direction (X direction) of the substrate P is a row direction. The logical information of the pixel is 1-bit data of "0" or "1". The logical information "0" means that the intensity of the spot SP irradiated on the substrate P is at a low level (not depicted), and the logical information "1" means that the intensity of the spot SP irradiated on the substrate P is at a high level (depicted).

The logic information of the pixels of 1 row of the pattern data corresponds to 1 drawing line SLn (SL1 to SL 6). Therefore, the number of pixels in 1 row is determined by the size of the pixels on the irradiated surface of the substrate P and the length of the drawing line SLn. The dimension Pxy of the 1 pixel is set to be equal to or larger than the size φ of the light spot SP, for example, when the effective size φ of the light spot SP is 3 μm, the dimension Pxy of the 1 pixel is set to be equal to or larger than 3 μm square. The intensity of the spot SP projected onto the substrate P along 1 drawing line SLn (SL1 to SL6) is modulated according to the logic information of the pixels in 1 column. When the light source device 14 is a fiber amplifier laser light source, as disclosed in international publication No. 2015/166910, the pulsed seed light (emission frequency Fa) in the infrared wavelength region incident on the fiber amplifier is switched at high speed to either of the rapid pulse light with a large peak intensity and the slow pulse light with a low peak intensity, based on the logical information "1" and "0" of the pixel of the pattern data transmitted from the control device 18.

Further, the optical element for selection AOMn is such that the diffraction efficiency and the responsiveness become higher when the diameter of the light beam LB incident on the optical element for selection AOMn becomes smaller. Therefore, when the beam LB incident on the selective optical element AOMn is made parallel, a beam shaping optical system in which the diameter of the beam LB incident on the selective optical element AOMn is reduced in a parallel state may be provided. In embodiment 1, the beam LB emitted from the light source device 14 is set to be a parallel beam having a diameter of 1mm or less, and thus the optical element AOMn for selection can be directly transmitted in this state.

In the above configuration of fig. 2 and 3, the light source device 14 and the light beam switching unit BDU constitute light beam supply means (light beam generating means) for supplying the light beam LBn for drawing to each of the scanning units Un. More precisely defined, the beam supply means for the scanning unit U in FIG. 2 is constituted by the light source device 14, the mirrors M, the optical element AOM for selection, and the incident mirror IM, the beam supply means for the scanning unit U is constituted by the light source device 14, the mirrors M to M, the optical element AOM for selection, the AOM, and the incident mirror IM, the beam supply means for the scanning unit U is constituted by the light source device 14, the mirrors M to AOM, the optical element AOM for selection, the AOM, and the incident mirror IM, the beam supply unit to the scanning unit U2 is constituted by the light source device 14, mirrors M1 to M12, optical elements for selection AOM5, AOM6, AOM3, AOM4, AOM1, AOM2, and an incidence mirror IM 2.

Next, the configuration of the scanning unit (optical beam scanning device) Un will be described. Since the respective scanning units Un (U1 to U6) have the same configuration, only the scanning unit U1 will be described in a simplified manner. The scanning unit U1 includes at least mirrors M20 to M24, a polygon mirror PM, and an f θ lens system FT. Although not shown in fig. 2, a 1 st cylindrical lens CY1 is disposed in front of the polygon mirror PM as viewed in the traveling direction of the luminous flux LB1, and a 2 nd cylindrical lens CY2 is disposed after the f θ lens system FT. The 1 st and 2 nd cylindrical lenses CY1 and CY2 will be described in detail below with reference to fig. 4.

The light beam LB1 reflected in the-Z direction by the incident mirror IM1 is incident on the mirror M20, and the light beam LB1 reflected by the mirror M20 travels in the-X direction and is incident on the mirror M21. The light beam LB1 reflected in the-Z direction by the mirror M21 enters the mirror M22, and the light beam LB1 reflected by the mirror M22 travels in the + X direction and enters the mirror M23. The reflecting mirror M23 reflects the incident light beam LB1 toward the reflecting surface RP of the polygon mirror PM.

The polygon mirror PM reflects the incident light beam LB1 toward the f θ lens system FT and to the + X direction side. The polygon mirror PM deflects (reflects) the incident light beam LB1 one-dimensionally in a plane parallel to the XY plane in order to scan the spot SP of the light beam LB1 on the irradiated surface of the substrate P. Specifically, the polygon mirror (rotary polygon mirror, movable deflecting member) PM is a rotary polygon mirror having a rotation shaft AXp extending in the Z-axis direction and a plurality of reflection surfaces RP formed around the rotation shaft AXp (in the present embodiment, the number Np of reflection surfaces RP is set to 8). By rotating the polygon mirror PM in a predetermined rotational direction about the rotational axis AXp, the reflection angle of the pulse-shaped luminous flux LB1 irradiated on the reflection surface RP can be continuously changed. Thus, the spot SP of the beam LB1 irradiated onto the irradiated surface of the substrate P can be scanned in the main scanning direction (the width direction of the substrate P, the Y direction) by deflecting the beam LB1 by 1 reflection surface RP. That is, the spot SP of the light beam LB1 can be scanned in the main scanning direction by 1 reflection surface RP. Therefore, during 1 rotation of the polygon mirror PM, the number of drawing lines SL1 for scanning the spot SP on the irradiated surface of the substrate P is 8 at maximum, which is the same as the number of reflection surfaces RP. The polygon mirror PM is accurately rotated at a speed instructed by a rotation drive source (e.g., a digital motor, etc.), not shown, under the control of the control device 18.

The f θ lens system (scanning system lens, scanning optical system) FT is a scanning lens of a telecentric system that projects the light beam LB1 reflected by the polygon mirror PM onto the reflecting mirror M24. The light beam LB1 transmitted through the f θ lens system FT is projected as a spot SP onto the substrate P via the mirror M24. At this time, the mirror M24 reflects the light beam LB1 toward the substrate P on the XZ plane so that the light beam LB1 travels toward the central axis AXo of the rotary drum DR. The incident angle θ of the light beam LB1 toward the f θ lens system FT is changed according to the rotation angle (θ/2) of the polygon mirror PM. The f θ lens system FT projects the light beam LB1 to an image height position on the irradiated surface of the substrate P in proportion to the incident angle θ via the mirror M24. When the focal length is fo and the image height position is yo, the f θ lens system FT is designed so as to satisfy the relationship (distortion aberration) of yo ═ fo × θ. Therefore, the f θ lens system FT can accurately scan the light beam LB1 at a constant velocity in the Y direction. Further, a surface (parallel to the XY plane) on which the light flux LB1 entering the f θ lens system FT is one-dimensionally deflected by the polygon mirror PM is a surface including the optical axis AXf of the f θ lens system FT.

Fig. 3 is a specific configuration diagram showing the periphery of the selective optical element AOMn and the incidence mirror IMn. Since the configurations around the selective optical element AOMn and the incidence mirror IMn are the same, only the configurations around the selective optical element AOM1 and the incidence mirror IM1 will be described here as representative.

The light beam LB is incident on the selective optical element AOM1, and after passing through the selective optical element AOM4 and the mirrors M9 and M10 in the previous stage as shown in fig. 2, the light beam LB becomes a parallel light beam having a minute diameter (1 st diameter) of, for example, 1mm or less. During a period in which a drive signal (ultrasonic signal) is not input as a high-frequency signal (ultrasonic signal) (drive signal off), the optical element AOM1 for selection directly transmits the incident light beam LB without diffracting it. The transmitted light beam LB passes through a condenser lens G1 and a collimator lens G2a provided on the optical path thereof along the optical axis AXa, and enters a rear-stage optical element for selection AOM 2. At this time, the central axis of the light beam LB having passed through the selection optical element AOM1 and then passed through the condenser lens G1 and the collimator lens G2a passes through the optical axis AXa. The condenser lens G1 condenses the light beam LB (parallel light beam) transmitted through the selective optical element AOM1 so that the light beam LB becomes a beam waist at a position of the surface p1 located between the condenser lens G1 and the collimator lens G2 a. The collimator lens G2a collimates the beam LB diverged by the condenser lens G1 into a parallel beam. The diameter of the light beam LB collimated by the collimator lens G2a becomes the 1 st diameter. The rear focal point of the condenser lens G1 and the front focal point of the collimator lens G2a are within a predetermined allowable range, and the front focal point of the condenser lens G1 and the diffraction point in the selective optical element AOM1 are within a predetermined allowable range. The condenser lens G1 and the collimator lens G2a constitute a relay lens system.

On the other hand, while the drive signal, which is a high-frequency signal, is applied to the selective optical element AOM1, the selective optical element AOM1 generates a light beam LB1 (diffracted light) which diffracts the incident light beam LB. The light beam LB1 (parallel light beam) deflected in the-Z direction at a diffraction angle corresponding to the frequency of the high-frequency signal passes through the condenser lens G1 and enters the incident mirror IM6 provided on the plane p 1. The condenser lens G1 condenses (converges) the light beam LB1 as follows: the light beam LB1 is refracted so that the central axis AXb of the light beam LB1 deflected in the-Z direction is parallel to the optical axis AXa through which the light beam LB passes, and the light beam LB1 is made to be a beam waist on or near the reflection surface of the incidence mirror IM 1. The light beam LB1 is reflected in the-Z direction by the incident mirror IM6 provided on the-Z direction side with respect to the optical path of the light beam LB transmitted through the selective optical element AOM1, and is incident on the scanning unit U1 via the collimator lens G2 b. The collimator lens G2b converts the light beam LB1 converged/diverged by the condenser lens G1 into a parallel light beam coaxial with the optical axis of the collimator lens G2 b. The diameter of the beam LB1 that is made into a parallel beam by the collimator lens G2b becomes the 1 st diameter. The rear focal point of the condenser lens G1 and the front focal point of the collimator lens G2b are within a predetermined allowable range. The condenser lens G1 and the collimator lens G2b constitute a relay lens system. The condenser lens G1, the collimator lenses G2a, and G2b in fig. 3 are also arranged on the optical path after each of the other optical elements AOM2 to AOM6 shown in fig. 2 under the same conditions as in fig. 3.

In the scanning unit U1 shown in fig. 2, the optical axis of the f θ lens system FT is parallel to the XY plane, and therefore the reflection plane of the front end mirror M24 is disposed so as to be inclined at an angle other than 45 degrees with respect to the XY plane so that the central axis (principal ray) of the light beam LB1 projected from the scanning unit U1 onto the substrate P is directed toward the central axis AXo of the rotary drum DR. However, when the entire scanning units U1 to U6 are inclined in the XZ plane so that the optical axis of the f θ lens system FT is inclined with respect to the XY plane, the optical axis of the f θ lens system FT may be bent at 90 degrees by the mirror M24.

Fig. 4 is a diagram showing a specific configuration of the scanning unit U1, and is a diagram obtained by observing from a plane (XZ plane) orthogonal to a plane (a plane parallel to the XY plane) including the scanning direction (deflection direction) of the light beam LB 1. In fig. 4, the optical axis AXf of the f θ lens system FT is arranged parallel to the XY plane, and the front end mirror M24 is arranged so that the optical axis AXf is bent at 90 degrees. In the scanning unit U1, along a light transmission path of the light beam LB1 from the incident position of the light beam LB1 to the surface to BE irradiated (substrate P), a mirror M20, a beam expander BE, a parallel plate HVP with a variable inclination angle, an aperture stop PA, a mirror M21, a 1 st cylindrical lens CY1, a spherical lens G10a, a mirror M22, a spherical lens G10b, a mirror M23, a polygonal mirror PM, an f θ lens system FT, a mirror M24, and a 2 nd cylindrical lens CY2 are provided.

The light beam LB1 of the parallel light beams reflected in the-Z direction by the incidence mirror IM1 shown in fig. 3 is incident on the mirror M20 inclined at 45 degrees with respect to the XY plane. The mirror M20 reflects the incident beam LB1 in the-X direction toward the mirror M21 distant from the mirror M20 in the-X direction. The light beam LB1 reflected by the mirror M20 passes through the beam expander BE and the aperture stop PA and enters the mirror M21. The beam expander BE expands the diameter of the transmitted light beam LB 1. The beam expander BE includes a condenser lens BE1 and a collimator lens BE2 that collimates the beam LB1 that has been converged and then diverged by the condenser lens BE 1. The beam LB6 is easily irradiated to the opening portion of the aperture stop PA by the beam expander BE. Further, between the condenser lens Be1 and the collimator lens Be2, a quartz parallel plate HVP as an optical member for offset is disposed, and the inclination angle of the parallel plate HVP with respect to the light beam LBn can Be changed in a plane parallel to the XZ plane by a drive motor or the like, not shown. By changing the inclination angle of the parallel plate HVP, the trace line SLn, which is the scanning locus of the spot SP scanned on the substrate P, can be shifted slightly (for example, several times to several tens times the effective diameter Φ of the spot SP) in the sub-scanning direction. This function will be described in detail below.

The mirror M21 is disposed to be inclined at 45 degrees with respect to the YZ plane, and reflects the incident light beam LB1 in the-Z direction toward the mirror M22 distant from the mirror M21 in the-Z direction. The light beam LB1 reflected in the-Z direction by the mirror M21 passes through the 1 st cylindrical lens CY1 (1 st optical component) and the spherical lens G10a, and reaches the mirror M22. The mirror M22 is disposed to be inclined at 45 degrees with respect to the XY plane, and reflects the incident light beam LB1 in the + X direction toward the mirror M23. The light beam LB1 reflected by the mirror M22 enters the mirror M23 through the spherical lens G10 b. The reflecting mirror M23 bends the incident light beam LB1 in a plane parallel to the XY plane toward the polygon mirror (rotary polygon mirror, movable deflecting member) PM. The 1 reflection surface RP of the polygon mirror PM reflects the incident light beam LB1 in the + X direction toward the f θ lens system FT having the optical axis AXf extending in the X axis direction. The spherical lens G10a and the spherical lens G10b constitute a lens system (3 rd optical member) G10. The spherical lenses G10a and G10b have isotropic refractive power.

The 1 st cylindrical lens CY1, which is a plano-convex lens formed of a single lens, has refractive power (focusing power) in one direction, and has anisotropic refractive power. Fig. 5 is a schematic view of the optical path of the light beam LB from the aperture stop PA to the substrate P as viewed from a plane parallel to a plane including the deflection direction (main scanning direction) of the light beam LB, the plane being spread on the XY plane. As shown in fig. 5, the 1 st cylindrical lens CY1 one-dimensionally collects (converges) the light beam LB1 in the deflection direction of the light beam LB1 by the polygon mirror PM (the main scanning direction and the rotational direction within the plane perpendicular to the rotational axis AXp of the polygon mirror PM) such that the incident light beam LB1 becomes a beam waist on the plane p2 located in front of the polygon mirror PM. The light converging position (position of the surface p 2) in front of the polygon mirror PM is set to the 1 st position. This 1 st position is a position in front of the lens system G10 (spherical lenses G10a, 10 b). The 1 st cylindrical lens CY1 transmits the incident light beam LB1 as a parallel light beam without condensing it in a direction (sub-scanning direction) orthogonal to the deflecting direction (main scanning direction) of the light beam LB1 by the polygon mirror PM (see fig. 4). In this way, the 1 st cylindrical lens CY1 has a generatrix extending in a direction (sub-scanning direction) parallel to the X direction so that the light beam LB1 transmitted through the 1 st cylindrical lens CY1 does not converge in a direction (sub-scanning direction) orthogonal to the deflection direction of the polygon mirror PM.

The lens system G10 (spherical lenses G10a and G10b) makes the light beam LB1, which is condensed and then diverged by the 1 st cylindrical lens CY1, a substantially parallel light beam in the deflecting direction (main scanning direction and rotation direction) of the light beam LB1 by the polygon mirror PM (see fig. 5). The lens system G10 (spherical lenses G10a and G10b) condenses (converges) the parallel light flux LB1 transmitted through the 1 st cylindrical lens CY1 on the reflection surface RP of the polygon mirror PM in the direction (sub-scanning direction) orthogonal to the deflecting direction of the light flux LB1 of the polygon mirror PM (see fig. 4). Thus, the light beam LB1 to be projected onto the polygon mirror PM is converged on the reflection surface RP into a long shape (oblong shape) extending in a plane parallel to the XY plane. In this way, even when the reflection surface RP is inclined with respect to the Z direction (inclination of the reflection surface RP with respect to the normal line of the XY plane), the influence thereof can be suppressed by the 1 st cylindrical lens CY1 and the lens system G10, and the 2 nd cylindrical lens CY2 described below. For example, the irradiation position of the light beam LB1 (the drawing line SL1) irradiated onto the irradiated surface of the substrate P can be suppressed from being shifted in the X direction by a slight inclination error (surface inclination) of each of the reflecting surfaces RP of the polygon mirror PM, that is, the surface inclination of each of the reflecting surfaces RP can be corrected. The light flux LB1 reflected by the reflection surface RP is incident on the f θ lens system FT as it is in a substantially parallel form in the deflection direction (main scanning direction, rotation direction) of the light flux LB1 by the polygon mirror PM, and is incident on the f θ lens system FT in a state of diverging with a predetermined Numerical Aperture (NA) in the direction (sub-scanning direction) orthogonal to the deflection direction of the light flux LB1 by the polygon mirror PM.

Further, the rear focal point of the 1 st cylindrical lens CY1 corresponding to the refractive power in the deflecting direction of the polygon mirror PM (the main scanning direction of the spot SP) and the front focal point of the lens system G10 are set to coincide with each other on the surface p2 within a predetermined allowable range. The rear focal point of the lens system G10 and the front focal point of the f θ lens system FT are set to coincide with each other at the deflection position (on the reflection surface RP) of the polygon mirror PM within a predetermined allowable range.

The f θ lens system FT converges (condenses) the substantially parallel luminous flux LB1 reflected by the reflection surface RP on the substrate P in the deflecting direction (main scanning direction, rotating direction) of the luminous flux LB1 by the polygon mirror PM as shown in fig. 5. Further, as shown in fig. 4, the f θ lens system FT makes the light flux LB1, which is reflected by the reflection surface RP and then diverged, substantially parallel to the deflection direction (sub-scanning direction) of the light flux LB1 of the polygon mirror PM, and projects the light flux LB1 toward the 2 nd cylindrical lens CY 2.

The plano-convex 2 nd cylindrical lens (2 nd optical member) CY2 formed of a single lens is a lens having a generatrix in a direction parallel to the Y direction (main scanning direction) and having refractive power having anisotropy of focusing power in one direction (sub scanning direction). The 2 nd cylindrical lens CY2 directly transmits the incident light beam LB1 as it is in the deflection direction (main scanning direction, rotation direction) of the light beam LB1 by the polygon mirror PM. Therefore, as shown in fig. 5, the light beam LB1 transmitted through the 2 nd cylindrical lens CY2 is converged on the substrate P so as to become a beam waist by the refractive power of the f θ lens system FT in the deflection direction (main scanning direction, rotation direction) of the light beam LB1 by the polygon mirror PM. On the other hand, the 2 nd cylindrical lens CY2 condenses (converges) the incident substantially parallel light flux LB1 on the substrate P so as to be a beam waist, as shown in fig. 4, in a direction (sub-scanning direction) orthogonal to the deflecting direction (main scanning direction) of the light flux LB1 by the polygon mirror PM. Therefore, the light beam LB1 projected onto the substrate P forms a substantially circular spot SP (for example, 3 μm in diameter) on the substrate P. As described above, the 1 st cylindrical lens CY1 and the 2 nd cylindrical lens CY2 are arranged so as to have focusing forces (refractive forces) in directions orthogonal to each other and so that generatrices thereof are orthogonal to each other. Thus, the 1 st cylindrical lens CY1 functions to converge the light flux LBn one-dimensionally in the main scanning direction on the surface p2 in front of the lens system G10, and then converge the light flux LBn one-dimensionally in the sub-scanning direction on the reflection surface RP of the polygon mirror PM, and the 2 nd cylindrical lens CY2 functions to converge the light flux LBn one-dimensionally in the sub-scanning direction after the f θ lens system FT.

As described above, since the 1 st cylindrical lens CY1 and the 2 nd cylindrical lens CY2 formed of a single lens are provided so that the generatrices thereof are orthogonal to each other, spherical aberration of the light flux LBn in both the deflecting direction (main scanning direction) of the light flux LBn by the polygon mirror PM and the sub-scanning direction orthogonal to the main scanning direction can be corrected favorably by the lens system G10. Therefore, deterioration of the image forming performance on the substrate P can be suppressed. Further, by providing the 1 st cylindrical lens CY1 and the 2 nd cylindrical lens CY2, it is possible to suppress the deviation of the drawing line SLn in the X direction (sub-scanning direction) due to the minute slope errors (surface inclinations) of the reflection surface RP of the polygon mirror PM, that is, to perform the surface inclination correction, as in the conventional case.

The position (optimum focus position) of the spot SP of the light beam LBn projected onto the substrate P is the main scanning direction (deflection direction) and the position orthogonal to the main scanning directionThe sub-scanning direction is optically designed to be uniform within a predetermined allowable range. Further, the numerical aperture NA in the main scanning direction of the light beam LBn (spot SP) to be projected onto the substrate P_yAnd a numerical aperture NA in a sub-scanning direction orthogonal to the main scanning direction_xAre designed to be equal (or consistent) within a predetermined allowable range. Furthermore, in the present embodiment 1, the numerical aperture NA _xNumerical aperture of about equal to NA_yTherefore, the numerical aperture of the light beam LBn to be projected onto the substrate P may be represented by NA alone. The spherical aberration of the light beam LBn is expressed as a relative deviation in the focusing direction of the respective condensed positions of the light beams having different tilt angles (incident angles to the optimal focal plane) with respect to the central axis (principal ray) of the light beam LBn when the light beam LBn is condensed toward the optimal focal plane in design. The light ray having an inclination angle β with respect to the central axis (principal ray) of light beam LBn perpendicular to the best focus plane is represented by a numerical aperture Na β calculated by sin β. The maximum numerical aperture NA of the light beam LBn is generally determined by the wavelength λ of the light beam LBn, the effective diameter φ of the spot SP, and the focal length of the f θ lens system FT.

Next, a method of determining the focal length of each of the 1 st cylindrical lens CY1, the 2 nd cylindrical lens CY2, the lens system G10, and the f θ lens system FT, the aperture stop diameter of the aperture stop PA, and the expansion magnification of the beam expander BE will BE described. And then, with f_C1Denotes the focal length of the 1 st cylindrical lens CY1, denoted by f_C2Denotes the focal length of the 2 nd cylindrical lens CY2, denoted by f_GThe focal length of the lens system G10 is denoted f θ, and the focal length of the f θ lens system FT is denoted f θ. Further, the aperture diameter of the aperture stop PA is set to φ a.

Focal length f_C1、f_C2、f_GAnd f θ have the relationship of formula (1) shown below. Based on the equation (1), the respective focal lengths of the 1 st cylindrical lens CY1, the 2 nd cylindrical lens CY2, the lens system G10, and the f θ lens system FT are determined, whereby the numerical aperture NA of the light beam LBn to be projected onto the substrate P can be made to be equal to_xAnd numerical aperture NA_yAre equal.

f_G ²/f_C1＝fθ²/f_C2…(1)

The aperture stop diameter Φ a and the numerical aperture NA (═ NA)_x≒NA_y) Has the relationship of the following formula (2).

φa＝2×NA(fθ×f_C1/f_G)＝2×NA×(f_G×f_C2/fθ)…(2)

By determining the aperture stop diameter Φ a based on this equation (2), a desired numerical aperture can be obtained. Further, the larger the expansion magnification of the beam expander BE, the more the light quantity blocked by the aperture stop PA becomes, and therefore the larger the light quantity loss becomes. On the other hand, the smaller the expansion magnification of the beam expander BE, the smaller the effective numerical aperture at the image plane (on the substrate P) becomes, and thus the resolution (fineness of the diameter Φ of the spot SP) decreases. Therefore, it is preferable to set the expansion ratio of the beam expander BE to an optimum value in consideration of the balance between the light amount and the resolution.

When the optical specifications of the 1 st cylindrical lens CY1, the 2 nd cylindrical lens CY2, the f θ lens system FT, and the like are substantially determined, the spherical aberration S in the main scanning direction (deflection direction) of the light beam LBn is used₁And spherical aberration S in the sub-scanning direction orthogonal to the main scanning direction of the light beam LBn ₂The optical specification of the lens system G10 (spherical lenses G10a and 10b) is set so as to satisfy at least any one of the conditions of the following expressions (3) to (6). When the optical specification of only the f θ lens system FT is substantially determined, the optical specification of the lens system G10 (spherical lenses G10a and 10b) and the optical specifications of the 1 st cylindrical lens CY1 and the 2 nd cylindrical lens CY2 are set so as to satisfy any of the conditions of the expressions (3) to (6).

|S₁－S₂|＜S_C1×fθ²/f_G ²－S_C2…(3)

S₁＜S_C1×fθ²/f_G ²And S is₂＜S_C2…(4)

|S₁－S₂|＜λ/NA_y ²And | S₁－S₂|＜λ/NA_x ²…(5)

S₁＜λ/NA_y ²And S is₂＜λ/NA_x ²…(6)

Wherein, | S₁－S₂I represents spherical aberration S₁And spherical aberration S₂Absolute value of the difference, S_C1Represents the spherical aberration, S, produced by the 1 st cylindrical lens CY1 monomer_C2Which represents the spherical aberration generated by the 2 nd cylindrical lens CY2 alone, and λ represents the wavelength of the light beam LBn. Furthermore, the spherical aberration S₁And spherical aberration S₂Absolute value of the difference | S₁－S₂If is | S₂－S₁The same holds true. It is to be noted that the scanning unit U1 is described as an example, but the optical design is similarly performed for the other scanning units U2 to U6.

Here, in the conventional method, that is, when the extending direction of each generatrix of the 1 st cylindrical lens CY1 and the 2 nd cylindrical lens CY2 is set to be parallel to the main scanning direction (Y direction), the focal length f is set to be equal to or smaller than the focal length f_C1、f_C2And f θ have the relationship of the following formula (7). In this case, the light beam LBn to be projected onto the reflection surface RP of the polygon mirror PM is converged on the reflection surface RP into a long shape (oblong shape) extending in a direction parallel to the XY plane (main scanning direction) only by the 1 st cylindrical lens CY1 whose extension direction of the bus bar is parallel to the Y direction, and therefore the lens system G10 is not required.

f_C1×f_C2＝fθ²…(7)

The diameter Φ a of the circular opening of the aperture stop PA and the numerical aperture NA have the relationship of the following expression (8).

φa＝2×NA×fθ＝2×NA×(f_C1×f_C2/fθ)…(8)

[ examples ]

The surface inclination correction of embodiment 1 is compared with the surface inclination correction of the conventional embodiment. Since it is necessary to compare both under the same condition as much as possible, the numerical aperture NA and the specification of the light beam LBn to be incident on the scanning unit Un are the same. The light beam LBn is monochromatic light having a wavelength of 354.7nm and has an intensity of 1/e at a position spaced 0.25mm from the center of the optical axis (beam center line)²The unpolarized gaussian beam of (1). The numerical aperture NA is divided into numerical apertures NA in a plane (YZ plane) including the main scanning direction (deflection direction)_yAnd a numerical aperture NA in a plane (XZ plane) including a direction (sub-scanning direction) orthogonal to the main scanning direction_xAnd treated, and NA_y＝NA_x0.06. The f θ lens system FT and the 2 nd cylindrical lens CY2 are also the same as those of the conventional embodiment in the present embodiment 1. The focal length f θ of the f θ lens system FT is 100mm, and the focal length f of the plano-convex 2 nd cylindrical lens CY2 formed of a single lens is set to be equal to f θ_C2Is set to f_C214.5 mm. Further, in order to evaluate only the influence of spherical aberration generated by the 1 st cylindrical lens CY1 and the 2 nd cylindrical lens CY2, the f θ lens system FT is set to a lens having an ideal f- θ characteristic that does not generate aberration. First, a specific design example of an optical system for correcting the surface tilt of the scanner unit Un of the conventional system will be described with reference to comparative example 1, and then a specific design example of an optical system for correcting the surface tilt of the scanner unit Un of embodiment 1 will be described with reference to example 1. In embodiment 1 and the related art, the same reference numerals are given to the members that are common to each other or the members that are common to the functions. For simplicity, the mirrors M21, M22, and M23 are omitted in the design example (lens data).

Comparative example 1

In comparative example 1, the generatrices of both the 1 st cylindrical lens CY1 and the 2 nd cylindrical lens CY2 were set in the main scanning direction (Y direction), and the lens system G10 was not provided. Fig. 6 shows lens data of an optical design example of the beam expander BE to the 2 nd cylindrical lens CY2 in comparative example 1. Fig. 7 is a schematic diagram showing a state of a beam LBn from the beam expander BE to the substrate (image plane) P in comparative example 1 on a plane parallel to a plane including a deflection direction of the beam LBn (scanning direction of the spot SP). Fig. 8 is a schematic view of the beam expander BE shown in fig. 7 as viewing the light beam LBn on the reflection surface RP of the polygon mirror PM from a plane (a plane including the sub-scanning direction) perpendicular to the deflection direction (main scanning direction) of the light beam LBn. Fig. 9 is a schematic view of a state where light beam LBn from reflection surface RP to substrate (image plane) P of polygon mirror PM shown in fig. 7 is viewed from a plane orthogonal to the deflection direction (main scanning direction) of light beam LBn. In fig. 6, after reflection by the polygon mirror PM, the positive and negative signs of the surface interval and the radius of curvature are reversed. Fig. 7 to 9 are diagrams showing a case where the beam expander BE to the optical members (the 1 st cylindrical lens CY1, the 2 nd cylindrical lens CY2, and the like) of the substrate P in comparative example 1 are arranged at a reduced scale in accordance with the numerical example of fig. 6.

The beam LBn (effective beam diameter Φ set to 0.5mm) of the parallel beam incident on the scanning unit Un is converted into a parallel beam expanded by the beam expander BE composed of 5 spherical lenses LG1 to LG5, and then shaped into a beam having a circular cross section with a specific diameter by the aperture stop PA. The aperture diameter φ a of the aperture stop PA is set to 12mm based on the above equation (8). The strength is 1/e on the axis²The position of (2) is set to 6mm, which is the radius of the aperture stop diameter φ a, and the expansion ratio of the beam expander BE is set to 24 times. At this time, the ratio of the light amount loss by the aperture stop PA becomes about 13.5%.

The 1 st cylindrical lens CY1, which is disposed behind the beam expander BE and is a plano-convex lens, condenses the incident light beam LBn on the reflection surface RP of the polygon mirror PM in a direction orthogonal to the deflecting direction (main scanning direction) of the light beam LBn by the polygon mirror PM (see fig. 8). Focal length f of 1 st cylindrical lens CY1_C1Is set to f based on the above formula (7)_C1693.1 mm. The reflection surface RP of the polygon mirror PM is located at the rear focal point of the 1 st cylindrical lens CY 1. Further, in the deflection direction (main scanning direction) of the light flux LBn by the polygon mirror PM, the light flux LBn transmitted through the 1 st cylindrical lens CY1 maintains a parallel light state (see fig. 7). Therefore, the light beam LBn to be projected onto the polygon mirror PM is converged into a long stripe shape (oblong shape) extending in the deflection direction on the reflection surface RP.

The light flux LBn reflected on the reflection surface RP of the polygon mirror PM enters the f θ lens system FT having a focal length f θ of 100mm at an angle corresponding to the rotation angle of the polygon mirror PM. The reflection surface RP of the polygon mirror PM is disposed so as to reach the position of the front focal point of the f θ lens system FT. Therefore, the f θ lens system FT concentrates the light flux LBn reflected by the reflection surface RP of the polygon mirror PM on the irradiated surface (image surface) of the substrate P in a telecentric state in the deflection direction (main scanning direction) of the light flux LBn by the polygon mirror PM (see fig. 7). On the other hand, the f θ lens system FT converts the light beam LBn, which is reflected and diverged by the reflection surface RP of the polygon mirror PM, into parallel light in the sub-scanning direction (see fig. 9) orthogonal to the deflecting direction (main scanning direction) of the light beam LBn by the polygon mirror PM.

Light flux LBn transmitted through f θ lens system FT passes through the rear side of f θ lens system FT and has focal length f_C2The 2 nd cylindrical lens CY2 having a thickness of 14.5mm is also focused on the surface to be irradiated (image surface) of the substrate P in the sub-scanning direction of the light beam LBn by the polygon mirror PM (see fig. 9). The position of the 2 nd cylindrical lens CY2 is determined so that the converging position in the main scanning direction of the light beam LBn by the polygon mirror PM and the converging position in the sub scanning direction coincide with each other within a predetermined allowable range in the focusing direction, and is set so that the converging position becomes the surface to be irradiated (image surface) of the substrate P.

Thus, when the light beam LBn is converged to the spot SP on the substrate P through the optical path created by the 1 st cylindrical lens CY1, the f θ lens system FT, and the 2 nd cylindrical lens CY2, aberration occurs in which the converging position of the light beam LBn is greatly different between the main scanning direction and the sub-scanning direction. This is due to spherical aberration that occurs when the light beam LBn converges to a spot. Fig. 10 and 11 are diagrams illustrating a state of spherical aberration of the light beam LBn directed toward the substrate P, where fig. 10 shows a state of spherical aberration of the light beam LBn in the main scanning direction, and fig. 11 shows a state of spherical aberration of the light beam LBn in the sub-scanning direction.

As shown in fig. 10, the light flux LBn becomes a parallel light flux having a certain roughness in the main scanning direction, enters the f θ lens system FT, and is focused mainly at a predetermined Z position (focal position) on the principal ray (light flux center line) Lpr by the f θ lens system FT. At this time, the 2 nd cylindrical lens CY2 functions simply as a parallel plate. Maximum numerical aperture NA in the main scanning direction of light flux LBn emitted from f θ lens system FT_yIs based on the inclination angle (incident angle) beta a of the light ray LLa facing the converging point relative to the principal ray Lpr as measured by NA_ySin β a. The light beam LBn includes a light ray LLb having an incident angle smaller than the incident angle β a of the light ray LLa (the incident angle is β b), a light ray LLc having an incident angle smaller than the incident angle β b of the light ray LLb (the incident angle is β c), and the like. Here, when the converging point of the light ray LLa at the incident angle β a is the focal position Zma in the Z-axis direction, the focal position Zmb of the converging point of the light ray LLb at the incident angle β b and the focal position Zmc of the converging point of the light ray LLc at the incident angle β c are both shifted in the Z-axis direction from the focal position Zma. Such an offset is spherical aberration.

As shown in fig. 11, the light flux LBn becomes a divergent light flux in the sub-scanning direction, enters the f θ lens system FT, is converted into a parallel light flux by the f θ lens system FT, and is then refracted by the 2 nd cylindrical lens CY2 to be condensed at a predetermined Z position (focal position) on the principal ray (light flux center line) Lpr. Maximum numerical aperture NA in the sub-scanning direction of the light beam LBn emitted from the 2 nd cylindrical lens CY2_xSet to the maximum numerical aperture NA in the main scanning direction_yAnd (5) the consistency is achieved. Therefore, in the sub-scanning direction, according to NA_xEach of the focal position Zsa at which the light ray LLa (incident angle β a) determined as sin β a is focused, the focal position Zsb at which the light ray LLb (incident angle β b) having an incident angle smaller than the incident angle β a is focused, and the focal position Zsc at which the light ray LLc (incident angle β c) having an incident angle smaller than the incident angle β b is focused is also shifted in the Z-axis direction (focusing direction) by spherical aberration. In fig. 10 and 11, description is made on the way that spherical aberration occurs on the optical path from the f θ lens system FT to the substrate P, and the actual spherical aberration occurring in the light flux LBn reaching the substrate P is affected by various optical members (lenses, AOMs, mirrors) through which the light flux emitted from the light source device 14 of fig. 2 passes.

Fig. 12 and 13 show the maximum numerical aperture NA (═ NA) of light flux LBn based on the lens data of comparative example 1 shown in fig. 6_y≒NA_x) The spherical aberration characteristic of the light beam LBn obtained by simulation with 0.06 is assumed to be 0.06, with the abscissa axis indicating the focal position (μm) with the design best focus position as zero, and the ordinate axis indicating the maximum incident angle β a (NAa) of the light beam LLa corresponding to the maximum numerical aperture NA of the light beam LBn (sin β)a) Normalized to an angle of incidence β of 1.0(β max). Therefore, in fig. 12 and 13, for example, the incidence angle β of 0.5 means an angle half the maximum incidence angle β a. Further, a characteristic (a) shown by a solid line in fig. 12 is a spherical aberration characteristic in the main scanning direction of the light beam LBn projected onto the substrate P, and a characteristic (B) shown by a broken line is a spherical aberration characteristic in the sub-scanning direction of the light beam LBn projected onto the substrate P. Characteristic (C) shown in fig. 13 shows spherical aberration characteristics resulting from the difference [ (B) - (a) ] between characteristic (a) and characteristic (B) in fig. 12, and spherical aberration of several tens μm occurs due to deviation of the best focus position from the incident angle β of light beam LBn projected onto substrate P as spot SP.

Here, the characteristic (a) in fig. 12 is spherical aberration generated by the beam expander BE and the f θ lens system FT, and the characteristic (B) in fig. 12 is spherical aberration generated by a combined system of the beam expander BE, the 1 st cylindrical lens CY1, the f θ lens system FT, and the 2 nd cylindrical lens CY 2. Therefore, the characteristic (C) of the difference between the characteristics (a) and (B) mainly corresponds to the spherical aberration characteristics generated by the 1 st cylindrical lens CY1 and the 2 nd cylindrical lens CY 2.

(example 1)

In embodiment 1, as described above, the extending direction of the generatrix of the 1 st cylindrical lens CY1 is set as the sub-scanning direction (X direction), the extending direction of the generatrix of the 2 nd cylindrical lens CY2 is set as the main scanning direction (Y direction), and the lens system G10 is provided between the 1 st cylindrical lens CY1 and the polygon mirror PM. Fig. 14 shows lens data for optical design of the beam expander BE to the 2 nd cylindrical lens CY2 in embodiment 1. Fig. 15 is a schematic diagram of a state in which the beam LBn from the beam expander BE to the substrate (image plane) P in example 1 is observed in a plane parallel to a plane including the deflection direction of the beam LBn (scanning direction of the spot SP). Fig. 16 is a schematic diagram of a state in which the beam expander BE shown in fig. 15 is viewing the light beam LBn on the reflection surface RP of the polygon mirror PM in a plane (a plane including the sub-scanning direction) perpendicular to the deflection direction (main scanning direction) of the light beam LBn. Fig. 17 is a schematic view of light beam LBn from reflection surface RP to substrate (image plane) P of polygon mirror PM shown in fig. 15, viewed in a plane (a plane including the sub-scanning direction) orthogonal to the deflection direction (main scanning direction) of light beam LBn. In fig. 14, the polygon mirror PM reflects and then shows the surface interval and the positive or negative sign of the curvature radius. Fig. 15 to 17 show a case where the optical members (the 1 st cylindrical lens CY1, the 2 nd cylindrical lens CY2, and the like) of the beam expander BE to the substrate P in example 1 are arranged at an actual reduction ratio in accordance with the numerical example of fig. 14.

In example 1, the focal length f of the lens system G10 is set based on the above formula (1) such that the distance (optical path length) from the 1 st cylindrical lens CY1 to the image plane (irradiated surface of the substrate P) is shorter by about 300mm as compared with comparative example 1_GIs set to f_G201.2mm, the focal length f of the 1 st cylindrical lens CY1_C1Is set to f_C158 mm. Thus, in embodiment 1, a space-saving optical system can be realized as compared with the design example of comparative example 1. Further, since the housing of the scanner unit Un can be reduced in size, the scanner unit Un can be reduced in weight.

A beam LBn (effective diameter 0.5mm) of the parallel beam incident on the scanning unit Un is expanded by a beam expander BE composed of 4 spherical lenses LGa to LGd, and then shaped to a predetermined beam diameter by an aperture stop PA. The aperture diameter φ a of the aperture stop PA is set to 3.5mm based on the above equation (2). The intensity of the beam expanded by the beam expander BE is 1/e on the axis at a position spaced from the center by 1.75mm which is a half of the aperture stop diameter φ a²In the method (3), the expansion magnification of the beam expander BE is set to 7 times. Thus, the beam expander BE can BE designed more easily and spherical aberration generated by the beam expander BE can BE reduced, since the expansion ratio is smaller than in comparative example 1.

A focal length f arranged behind the beam expander BE and composed of a single lens_C1The 1 st cylindrical lens CY1, which is plano-convex of 58mm, condenses the incident light beam LBn on the surface p2 (1 st position) of the rear-side focal point of the 1 st cylindrical lens CY1 in the deflecting direction (main scanning direction) of the light beam LBn by the polygon mirror PM (see fig. 15). The surface p2 is located between the 1 st cylindrical lens CY1 and the lens system G10 disposed on the rear side of the 1 st cylindrical lens CY 1. In addition, in the sub-scanning orthogonal to the deflecting direction (main scanning direction) of the light flux LBn by the polygon mirror PMIn the scanning direction, the light beam LBn transmitted through the 1 st cylindrical lens CY1 maintains a parallel light state (see fig. 16).

Lens system G10 (focal length f) composed of 2 spherical lenses G10a and G10b_G201.2mm) is arranged such that the positions of the front focal point of the lens system G10 and the rear focal point of the 1 st cylindrical lens CY1 (the surface p2) coincide within a predetermined allowable range. Therefore, the light beam LBn transmitted through the lens system G10 is parallel to the light beam LBn in the main scanning direction (see fig. 15), and is focused on the reflection surface RP of the polygon mirror PM in the sub-scanning direction orthogonal to the main scanning direction of the light beam LBn (see fig. 16). The reflection surface RP of the polygon mirror PM is set to a position to reach the rear focal point of the lens system G10. Therefore, the light flux LBn to be projected onto the polygon mirror PM is converged on the reflection surface RP into a long stripe shape (oblong shape) extending in the deflection direction (main scanning direction).

The light flux LBn reflected on the reflection surface RP of the polygon mirror PM enters the f θ lens system FT having a focal length f θ of 100mm at an angle corresponding to the rotation angle of the polygon mirror PM. The f θ lens system FT is arranged such that the reflection surface RP of the polygon mirror PM reaches a position of a front focal point of the f θ lens system FT. Therefore, the f θ lens system FT converges the light flux LBn reflected by the reflection surface RP of the polygon mirror PM on the irradiated surface (image surface) of the substrate P in a telecentric state (state where the principal ray Lpr of the light flux LBn and the optical axis AXf of the f θ lens system FT are always parallel) in the deflection direction (main scanning direction) of the light flux LBn by the polygon mirror PM (see fig. 15). On the other hand, in the sub-scanning direction orthogonal to the main scanning direction, the f θ lens system FT converts the light flux LBn, which is reflected by the reflection surface RP of the polygon mirror PM and becomes a divergent light flux, into a parallel light flux (see fig. 17).

Finally, light flux LBn passing through f θ lens system FT passes through lens system FT at a focal length f_C2The 2 nd cylindrical lens CY2 having a thickness of 14.5mm is also focused on the surface to be irradiated (image plane) of the substrate P as the spot SP in the sub-scanning direction orthogonal to the deflecting direction (main scanning direction) of the light beam LBn by the polygon mirror PM (see fig. 17). The position of the 2 nd cylindrical lens CY2 is in the main scanning direction of the light beam LBn based on the polygon mirror PM The light converging position and the light converging position in the sub-scanning direction are determined so as to coincide with each other within a predetermined allowable range in the focusing direction, and the light converging position is set to be the surface to be irradiated (image surface) of the substrate P. In the above-described configurations of fig. 14 to 17 (and fig. 4 and 5), the optical systems up to the beam expander BE, the aperture stop PA, the mirror M21, the 1 st cylindrical lens CY1, the mirror M22, the lens system G10, and the mirror M23 function as a 1 st adjusting optical system including a 1 st optical element or a 1 st lens member (1 st cylindrical lens CY1) having refractive power with anisotropy, the 1 st adjusting optical system being configured to converge the light flux LBn to BE projected onto the polygon mirror PM (movable deflecting member) in the sub-scanning direction orthogonal to the main scanning direction. Further, in the configuration of fig. 14 to 17 (and fig. 4 and 5), the mirror M24 and the 2 nd cylindrical lens CY2 after the f θ lens system FT (scanning optical system) function as a 2 nd adjusting optical system including a 2 nd optical element or a 2 nd lens member (2 nd cylindrical lens CY2) having refractive power with anisotropy, the 2 nd adjusting optical system converging the light flux LBn directed from the f θ lens system FT toward the substrate P in the sub-scanning direction.

Fig. 18 and 19 show the spherical aberration characteristics of light beam LBn obtained by simulation based on the lens data of example 1 shown in fig. 14, with the maximum numerical aperture NAa of light beam LBn being 0.06, the horizontal axis showing the focal position (μm) with the designed best focus position as zero, and the vertical axis showing the angle of incidence β normalized in the same manner as in fig. 12 and 13. The characteristic (a) shown by the solid line in fig. 18 is a spherical aberration characteristic in the main scanning direction of the light beam LBn projected onto the substrate P, and the characteristic (B) shown by the broken line is a spherical aberration characteristic in the sub-scanning direction of the light beam LBn projected onto the substrate P. Further, the characteristic (C) shown in fig. 19 is a spherical aberration characteristic showing the difference [ (B) - (a) ] between the characteristic (a) and the characteristic (B) in fig. 18. Here, the characteristic (a) in fig. 18 is spherical aberration generated by a combined system of the beam expander BE, the 1 st cylindrical lens CY1, the lens system G10, and the f θ lens system FT, and the characteristic (B) in fig. 18 is spherical aberration generated by a combined system of the beam expander BE, the lens system G10, the f θ lens system FT, and the 2 nd cylindrical lens CY 2. Therefore, the characteristic (C) of the difference between the characteristics (a) and (B) mainly corresponds to the spherical aberration characteristics generated by the 1 st cylindrical lens CY1 and the 2 nd cylindrical lens CY 2.

As a result of the simulation, the absolute value of the image difference is reduced by about 1 digit in the case of example 1, compared with the characteristics (a) and (B) of the spherical aberration in comparative example 1 shown in fig. 12. As is clear from the characteristic (a) in fig. 18, since the spherical aberration generated by the 1 st cylindrical lens CY1 is corrected by the lens system G10, the shift of the best focus position of the light beam LBn projected onto the substrate P as the spot SP with respect to the incident angle β hardly occurs. The spherical aberration, which is the offset, satisfies the conditions of the above equations (4) and (6). Similarly, as is clear from the characteristic (B) in fig. 18, since the spherical aberration generated by the 2 nd cylindrical lens CY2 is corrected by the lens system G10, the shift of the best focus position of the light beam LBn projected onto the substrate P as the spot SP with respect to the incident angle β hardly occurs. The spherical aberration, which is the offset, satisfies the conditions of the above equations (4) and (6). As is clear from the characteristic (C) of fig. 19, since the spherical aberration generated by the 1 st cylindrical lens CY1 and the 2 nd cylindrical lens CY2 is corrected by the lens system G10, the difference between the best focus position of the light beam LBn projected onto the substrate P as the spot SP and the incident angle β hardly occurs. The difference in the best focus position, that is, the difference in spherical aberration satisfies the conditions of the above equations (3) and (5). In this way, it is effective to increase the maximum numerical aperture NAa of the light beam LBn to 0.07 or more in order to reduce the effective diameter of the spot SP projected onto the substrate P, in accordance with the reduction in spherical aberration of the light beam projected onto the substrate P and the reduction in the minimum line width of the pattern that can be drawn (high resolution).

As described above, the scanning unit Un in embodiment 1 includes, in order to scan the light beam LBn one-dimensionally on the substrate P while projecting the light beam LBn from the light source device 14 onto the substrate P: a 1 st cylindrical lens CY1 having a focusing force in one direction; a polygon mirror PM on which a light beam LBn transmitted through the 1 st cylindrical lens CY1 enters and which deflects the light beam LBn for one-dimensional scanning; an f θ lens system FT that enters the light beam LBn deflected by the polygon mirror PM and projects the light beam LBn to the substrate P in a telecentric state; and a 2 nd cylindrical lens CY2 which is incident with the light beam LBn transmitted through the f θ lens system FT and has a focusing force in one direction; further, the 1 st cylindrical lens CY1 and the 2 nd cylindrical lens CY2 are arranged to have focusing power (refractive power) in directions orthogonal to each other, and a lens system G10 for correcting aberration (spherical aberration) is provided between the 1 st cylindrical lens CY1 and the polygon mirror PM.

Accordingly, it is possible to correct the deviation of the projection position of the light flux LBn due to the surface inclination of each reflection surface of the polygon mirror PM, and to correct the spherical aberration generated by the 1 st cylindrical lens CY1 and the 2 nd cylindrical lens CY2 with a simple configuration. Therefore, deterioration of the imaging performance of the spot SP can be suppressed, thereby improving the resolution (fineness) of the pattern drawn on the substrate P. Further, the focal length f of the 1 st cylindrical lens CY1 can be set _C1And focal length f of the 2 nd cylindrical lens CY2_C2Since both are smaller than the focal length f θ of the f θ lens system FT, a space-saving optical system (see fig. 7 to 9 and 15 to 17) can be realized, and the housing of the scanning unit Un can be reduced in size, thereby reducing the weight.

The 1 st cylindrical lens CY1 condenses the incident light flux LBn in front of the polygon mirror PM in the deflecting direction of the polygon mirror PM, and the lens system G10 makes the light flux LBn condensed and diverged by the 1 st cylindrical lens CY1 parallel in the deflecting direction, and condenses the incident light flux LBn on the reflection surface RP of the polygon mirror PM in the sub-scanning direction orthogonal to the deflecting direction. Thus, the light beam LBn to be projected onto the polygon mirror PM can be converged into a long stripe shape (oblong shape) extending in the deflection direction on the reflection surface RP. The f θ lens system FT converges the incident light flux LBn on the substrate P in the deflection direction, and converges the light flux LB converged and diverged on the reflection surface RP by the lens system G10 in a direction orthogonal to the deflection direction to be parallel light, and the 2 nd cylindrical lens CY2 converges the incident light flux LBn on the substrate P in a direction orthogonal to the deflection direction. Thus, even when the reflection surface RP is inclined with respect to the Z direction (inclination of the reflection surface RP with respect to the normal to the XY plane), since the reflection surface RP and the substrate P are in a conjugate relationship (image forming relationship) in the sub-scanning direction, it is possible to suppress the projection position of the light beam LBn on each reflection surface RP from being displaced in the sub-scanning direction.

[ modification 1 ]

According to embodiment 1, as shown in example 1 (fig. 14), the surface on the light beam incident side of each of the 1 st cylindrical lens CY1 and the 2 nd cylindrical lens CY2 is a cylindrical surface having a constant radius of curvature in the sub-scanning direction, and the surface on the light beam emitting side is a flat surface and is formed of lenses. However, the cylindrical surfaces of the 1 st cylindrical lens CY1 and the 2 nd cylindrical lens CY2 may be curved surfaces (aspherical surfaces in a cross-sectional shape perpendicular to the generatrix) formed by smoothly connecting a plurality of surfaces having slightly different radii of curvature. The planar side of each of the 1 st cylindrical lens CY1 and the 2 nd cylindrical lens CY2 may be processed into a cylindrical surface having a predetermined radius of curvature (∞ other than infinity) in the main scanning direction or the sub-scanning direction. The wavelength λ of the light flux LBn (light flux emitted from the light source device 14) to be incident on each of the scanning units Un is not limited to the wavelength of 354.7nm in the ultraviolet region set in example 1 and comparative example 1, and may be other wavelengths (light in the visible region and infrared region). Further, when achromatization is performed by the lens system G10, a plurality of light fluxes having different wavelengths can be coaxially (or parallelly) incident on the polygon mirror PM, and the surface of the substrate P can be scanned by a plurality of spots SP having different wavelengths. Alternatively, the light beam LBn may be made into a broad-band light having an intensity distributed in a fixed wavelength range with respect to the center wavelength by achromatization of the lens system G10. The light beam LBn may have a polarized component but not a non-polarized component, or may have a uniform intensity distribution (a substantially rectangular or trapezoidal distribution) instead of a gaussian distribution in the beam cross section.

[ modification 2 ]

In embodiment 1 described above, the beam LBn is deflected using the polygon mirror PM, but the beam LBn may be deflected using a galvanometer mirror (movable deflecting member, oscillating mirror) that can oscillate. In this case, since the light flux LBn reflected by the galvanometer mirror is also projected onto the substrate P (the surface to be irradiated) through the f θ lens system FT, when it is necessary to correct the surface inclination of the reflecting surface of the galvanometer mirror, it is sufficient to provide the 1 st cylindrical lens CY1 and the lens system G10 in the same manner in front of the galvanometer mirror, and provide the 2 nd cylindrical lens CY2 after the f θ lens system FT. The lens system G10 is composed of 2 spherical lenses G10a and G10b, but may be composed of a single lens or 3 or more lenses. The spherical lenses G10a and G10b constituting the lens system G10 may be aspherical lenses. Further, as the 1 st optical member CY1 and the 2 nd optical member CY2, cylindrical lenses are used, but any lenses may be used as long as the refractive power in one direction is relatively large with respect to the refractive power in the direction orthogonal to the one direction. For example, toric lenses or anamorphic lenses may be used as the 1 st optical component CY1 and the 2 nd optical component CY 2.

[ modification 3 ]

According to embodiment 1, each of the 1 st and 2 nd cylindrical lenses CY1 and CY2 is formed of a single lens. Thus, the 1 st cylindrical lens CY1 and the 2 nd cylindrical lens CY2 can be manufactured and assembled (adjusted) easily, and the cost can be reduced. However, to correct the spherical aberration of the light flux LBn, the 2 nd cylindrical lens CY2 may be configured by a multi-lens in particular. When the 2 nd cylindrical lens CY2 is formed of a plurality of (for example, 2) lenses, it is necessary to perform an adjustment operation for aligning the rotational orientations of the generatrices between the plurality of lenses with high accuracy. Further, when the 2 nd cylindrical lens CY2 is configured by a plurality of (for example, 2) lenses, the direction in which the generatrix of the 1 st cylindrical lens CY1 extends can be made parallel to the main scanning direction as in comparative example 1, and spherical aberration of the light beam LBn projected onto the substrate P can be corrected favorably even if the lens system G10 is omitted. However, in this case, as shown in comparative example 1, it is necessary to set the focal length f of the 1 st cylindrical lens CY1_C1Longer than the focal length f θ of the f θ lens system FT, and therefore the entire length of the optical path of the scanning unit Un becomes longer. However, the focal length f of the 2 nd cylindrical lens CY2 is sometimes set_C2The focal length f theta of the f theta lens system FT is set to be small, and spherical aberration is suppressed to be small.

In the modification 3 or the embodiment 1 (fig. 14 to 17), a beam scanning apparatus (or a drawing apparatus) can be obtained which is provided on a substrate P (fig. 17)Irradiated object) one-dimensionally scans the spot SP of the light beam LBn, and is provided with: a 1 st cylindrical lens CY1 (1 st optical member) for projecting a light beam LBn converged in a sub-scanning direction onto a reflection surface RP of a polygon mirror PM (light beam deflecting member) for deflecting the light beam LBn; an f θ lens system FT (scanning optical system) for making the light beam LBn deflected by the polygon mirror PM enter, project it toward the substrate P, and perform one-dimensional scanning on the substrate P; and a 2 nd cylindrical lens CY2 (2 nd optical member) disposed between the substrate P and the f θ lens system FT and composed of a single lens or a plurality of lenses for converging the light beam LBn emitted from the f θ lens system FT in the sub-scanning direction; by making the focal length f theta of the f theta lens system FT and the focal length f of the 2 nd cylindrical lens CY2_C2Is f theta > f_C2Thereby reducing the spherical aberration of the light beam LBn incident on the substrate P with a predetermined numerical aperture.

[ 2 nd embodiment ]

As also described in fig. 4, in order to slightly shift the scanning line SLn in the sub-scanning direction (X direction), an optical path between the lens systems BE1 and BE2 constituting the beam expander BE in the scanning unit Un is provided with an inclinable parallel plate HVP as an optical member for software. Fig. 20A and 20B are diagrams illustrating a case where the drawing line SLn is shifted due to the inclination of the parallel plate HVP, and fig. 20A is a diagram illustrating a state where the incident plane and the exit plane of the parallel plate HVP, which are parallel to each other, are at 90 degrees with respect to the center line (principal ray) of the light beam LBn, that is, a state where the parallel plate HVP is not inclined in the XZ plane. Fig. 20B is a diagram showing a state in which the incident plane and the exit plane of the parallel plate HVP, which are parallel to each other, are inclined from 90 degrees with respect to the center line (principal ray) of the light beam LBn, that is, the parallel plate HVP is inclined at an angle η with respect to the YZ plane.

Further, in fig. 20A and 20B, in a state where the parallel plate HVP is not inclined (angle η is 0 degrees), the optical axis Axe of the lens systems Be1 and Be2 is set to pass through the center of the circular opening of the aperture stop PA, and the center line of the light flux LBn to Be incident on the beam expander Be is adjusted to Be coaxial with the optical axis Axe. The position of the rear focal point of the lens system Be2 is arranged to coincide with the position of the circular opening of the aperture stop PA. The position of the aperture stop PA is set to be a position substantially corresponding to the pupil when viewed from the position of the reflection surface RP of the polygon mirror PM (or the position of the front focal point of the f θ lens system FT) in the sub-scanning direction by the 1 st cylindrical lens CY1 and the lens system G10 (spherical lenses G10a, 10b) shown in fig. 16. On the other hand, in the main scanning direction, the aperture stop PA is disposed so as to be optically conjugate with the position of the front-side focal point of the f θ lens system FT, that is, the position of the entrance pupil. Therefore, when the parallel plate HVP is inclined at the angle η, the center line of the light beam LBn (here, a divergent light beam) that is incident on the lens system Be2 through the parallel plate HVP is slightly shifted in parallel to the-Z direction with respect to the optical axis Axe, the light beam LBn that is emitted from the lens system Be2 is converted into a parallel light beam, and the center line of the light beam LBn is slightly inclined with respect to the optical axis Axe.

Since the position of the rear focal point of the lens system Be2 is arranged to coincide with the position of the circular opening of the aperture stop PA, the light beam LBn (parallel light beam) obliquely emitted from the lens system Be2 continues to Be projected to the circular opening without shifting in the Z direction on the aperture stop PA. Thus, the 1/e of the intensity distribution of light beam LBn passing through the circular opening of aperture stop PA²Is directed to the 1 st cylindrical lens CY1 of the latter stage at an angle slightly inclined in the sub-scanning direction in the XZ plane with respect to the optical axis Axe in a state where the intensity of the flat region of (a) has been accurately weakened. The aperture stop PA slightly shifts the position on the reflection surface of the polygon mirror PM of the light beam LBn (condensed in the sub-scanning direction) to be incident on the reflection surface RP of the polygon mirror PM, in accordance with the pupil position, in accordance with the inclination angle in the sub-scanning direction of the light beam LBn passing through the circular opening of the aperture stop PA, when viewed from the reflection surface RP of the polygon mirror PM in the sub-scanning direction. Therefore, the light flux LBn reflected by the reflection surface RP of the polygon mirror PM is also incident on the f θ lens system FT in a state slightly shifted in the Z direction with respect to a plane including the optical axis AXf of the f θ lens system FT shown in fig. 4 and parallel to the XY plane. As a result, in the case of the optical path shown in fig. 17, the light beam LBn to be incident on the 2 nd cylindrical lens CY2 is slightly inclined in the sub-scanning direction, and the position of the spot SP of the light beam LBn to be projected onto the substrate P is slightly shifted in the sub-scanning direction. In fig. 4 and 20, the beam expansion is configured Both of the lens systems BE1, BE2 of the device BE are set to spherical lenses (convex lenses) having positive refractive power, but the lens system BE1 on the incident side of the light beam LBn may BE set to a spherical lens (concave lens) having negative refractive power. In this case, the light beam LBn emitted from the lens system Be1 is not converged and becomes a divergent light beam, and is incident on the lens system Be2, and is converted into a parallel light beam with an enlarged beam diameter by the lens system Be 2.

When the generatrix of the 1 st cylindrical lens CY1 and the generatrix of the 2 nd cylindrical lens CY2 are arranged in parallel to each other and the 2 nd cylindrical lens CY2 is formed as a single lens as in comparative example 1, a large spherical aberration remains as shown in fig. 12 and 13. Therefore, when the parallel plate HVP is installed in the beam expander BE (fig. 7 and 8) of comparative example 1 and tilted, the position of the light beam LBn entering the 2 nd cylindrical lens CY2 or the tilt thereof slightly changes in the sub-scanning direction, and a larger spherical aberration occurs. On the other hand, when the lens system G10 is provided in a case where the generatrix of the 1 st cylindrical lens CY1 and the generatrix of the 2 nd cylindrical lens CY2 are arranged in a mutually orthogonal relationship as in embodiment 1, or when the 2 nd cylindrical lens CY2 is configured by a plurality of lenses as described in modification 3, the spherical aberration can be corrected favorably to the effective size (diameter) Φ or less of the spot SP as shown in fig. 18 and 19. Therefore, when the parallel plate HVP is tilted, the increase of the spherical image difference generated by a slight change in the position of the light beam LBn to be incident on the 2 nd cylindrical lens CY2 or the tilt in the sub-scanning direction is also suppressed to be small.

Since the parallel plates HVP shown in fig. 4 (fig. 20) are provided for each of the scanning units Un, the inclination angle η of the parallel plates HVP of each of the scanning units Un can be continuously changed, and thus a partial portion in the sub-scanning direction of the pattern drawn on the substrate P can be expanded and contracted at a small ratio. Therefore, even when the substrate P partially expands and contracts in the longitudinal direction (sub-scanning direction) of the substrate P, the overlay accuracy of the pattern for the 2 nd layer in the overlay exposure (drawing) with respect to the base pattern (1 st layer pattern) formed on the substrate P can be maintained well. The local expansion and contraction in the longitudinal direction (sub-scanning direction) of the substrate P can be predicted before each pattern drawing of the scanning unit Un by, for example, the following method: alignment marks formed on both sides of the substrate P in the width direction at a fixed pitch (for example, 10mm) in the longitudinal direction are enlarged by an alignment microscope, and sequentially picked up by an image pickup device, and a change in the longitudinal direction of the mark position (a change in the pitch of the marks, etc.) is subjected to image analysis. An example of the arrangement of the alignment mark and the arrangement of the alignment microscope is disclosed in, for example, international publication No. 2015/152218.

Claims (12)

1. A drawing device that one-dimensionally scans a light beam for pattern drawing in a main scanning direction on an object to be irradiated, and relatively moves the object to be irradiated and the light beam in a sub-scanning direction intersecting the main scanning direction, thereby drawing a pattern on the object to be irradiated, the drawing device comprising:

A light beam generating device for generating the light beam;

a beam expander that converts the light beam from the light beam generator into a parallel light beam having an enlarged beam diameter;

a beam deflecting means for deflecting the beam converted by the beam expander in one dimension in a direction corresponding to the main scanning direction after the beam is incident;

a scanning optical system configured to cause the one-dimensionally deflected light beam to enter and condense a light spot of the light beam on the irradiation target;

a 1 st optical system which is provided between the beam expander and the beam deflecting member, and includes a 1 st optical element having an anisotropic refractive power, the 1 st optical system being configured to allow the beam converted by the beam expander to enter and to converge the beam projected onto the beam deflecting member in a direction corresponding to the sub-scanning direction;

a 2 nd optical system including a 2 nd optical element having an anisotropic refractive power, the 2 nd optical system converging the light flux emitted from the scanning optical system and directed toward the irradiation object in the sub-scanning direction; and

and a shift optical member provided in an optical path of the beam expander, the shift optical member shifting the optical path of the light beam in a direction corresponding to the sub-scanning direction.

2. The drawing apparatus according to claim 1, wherein the beam expander includes a 1 st lens system for allowing the light beam from the light beam generating apparatus to enter, and a 2 nd lens system for converting the light beam passing through the 1 st lens system into a parallel light beam;

the offset optical member is a parallel plate whose inclination angle is variably disposed between the 1 st lens system and the 2 nd lens system.

3. The rendering device according to claim 2, further comprising an aperture stop disposed at a position of a rear focal point of the 2 nd lens system of the beam expander, for reducing an intensity of a gentle region in an intensity distribution of the light beam expanded by the beam expander.

4. The drawing apparatus according to claim 3, wherein the beam deflecting member has a reflecting surface that reflects the beam from the beam expander toward the scanning optical system and that changes a direction angle corresponding to the main scanning direction;

the reflection surface of the beam deflecting member is disposed so as to be optically conjugate with the irradiation target via the scanning optical system and the 2 nd optical system in a direction corresponding to the sub-scanning direction, and is disposed at a position of a front focal point of the scanning optical system in a direction corresponding to the main scanning direction.

5. The drawing device according to claim 4, wherein the position of the aperture stop is set to be a position of a pupil of the 1 st optical system in a direction corresponding to the sub-scanning direction when viewed from the reflection surface of the light beam deflecting member, and is set to be optically conjugate with a position of the reflection surface of the light beam deflecting member or a position of a front focal point of the scanning optical system via the 1 st optical system in the direction corresponding to the main scanning direction.

6. The drawing device according to claim 5, wherein the 1 st optical element of the 1 st optical system is a 1 st cylindrical lens that has a refractive power only in a direction corresponding to the main scanning direction and that causes the light flux passing through the aperture stop to enter;

the 2 nd optical element of the 2 nd optical system is a 2 nd cylindrical lens having a refractive power only in a direction corresponding to the sub scanning direction.

7. The rendering device according to claim 6, wherein the 1 st optical system includes a spherical or aspherical lens system having an isotropic refractive power that causes the light flux passing through the 1 st cylindrical lens to be incident thereon and to be emitted toward the reflective surface of the light flux deflecting member.

8. The drawing device as claimed in claim 7, wherein a numerical aperture NA in the main scanning direction of the light beam projected onto the irradiation object is set so as to be larger than a numerical aperture NA of the light beam projected onto the irradiation object_yAnd a numerical aperture NA in the sub-scanning direction_xEqual within a predetermined tolerance range,

the focal length of the 1 st cylindrical lens is set to f_C1Setting the focal length of the 2 nd cylindrical lens as f_C2Setting the focal length of the spherical or aspherical lens system to f_GAnd when the focal length of the scanning optical system is f θ, the following relationship is obtained:

f_G ²/f_C1＝fθ²/f_C2。

9. the rendering apparatus of claim 8,

the aperture stop has a function of shaping the light beam incident on the 1 st cylindrical lens to a diameter phi_aThe opening of the light beam of circular cross-section of (1),

is set to be thrownThe numerical aperture of the light beam incident on the irradiation object is set to

The diameter phi of the aperture diaphragm_aThe following relationships are established:

φ_a＝2×NA(fθ×f_C1/f_G)＝2×NA×(f_G×f_C2/fθ)。

10. the drawing device according to any one of claims 1 to 5, wherein a focal length of the 1 st optical element of the 1 st optical system is set to f_C1F is a focal length of the 2 nd optical element of the 2 nd optical system_C2When the focal length of the scanning optical system is f theta,

Will be the above focal length f_C1Set to be longer than the focal length f theta and set the focal length f_C2Is set to be smaller than the focal length f theta.

11. The rendering apparatus according to any one of claims 7 to 9, wherein a focal length of the 1 st cylindrical lens is set to f_C1F is the focal length of the 2 nd cylindrical lens_C2When the focal length of the scanning optical system is f theta,

setting the focal length f to be equal to or smaller than the focal length f_C1And the above focal length f_C2Are set to be smaller than the focal length f θ.

12. The drawing device according to any one of claims 1 to 5, wherein the 1 st optical element and the 2 nd optical element include any one of a cylindrical lens, a toric lens, and an anamorphic lens having different refractive powers in directions orthogonal to each other in a plane perpendicular to an optical path on which the light beam travels.

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