JP2006133431A - Exposure method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress decrease in the quality of an exposure pattern to be image-formed on a photosensitive material in an exposure apparatus. <P>SOLUTION: A spatial light modulator 80 is used, the modulator including a modulation element array unit 81 comprising a large number of two-dimensionally arrayed modulation elements 82 to modulate light Le at a wavelength in a UV region or a violet region emitted from a light source, a light transmitting window part 87 constituted of a transmitting material which transmits the light Le, and a sealing cover part 88 to hermetically seal the modulation element array unit 81 between itself and the light transmitting window 87, so that the light Le emitted from the light source 66 and made incident through the light transmitting window 87 is spatially modulated by the modulation element array 81 and is made to exit through the light transmitting window 87, and that the exiting light Le is image-formed onto a photosensitive material to expose the material. In this process, while the light Le emitting from the light source 66 is made incident on the spatial light modulator 80, the spatial modulator 80 is heated by a temperature control means 90 to increase the temperature of the spatial light modulator 80. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exposure method and apparatus, and more specifically, light emitted from a light source is spatially light-modulated by a modulation element array section in which a large number of modulation elements are arranged two-dimensionally to form an image on a photosensitive material. The present invention relates to an exposure method and apparatus for exposing a material.

  Conventionally, a laser beam carrying a wiring pattern spatially modulated by a mirror array section, which is a modulation element array section in which a large number of micromirrors, which are modulation elements, are two-dimensionally arranged, is laminated on a printed wiring board material. There has been known an exposure apparatus for forming a printed wiring board by forming an image on a photosensitive material that is formed and exposing the photosensitive material. The exposure apparatus includes a light source, a spatial light modulator that spatially modulates laser light emitted from the light source, a DMD (digital micromirror device) having the mirror array unit, and spatial light modulation by the DMD. And an imaging optical system for forming an image of the laser beam on the photosensitive material. The DMD uses a semiconductor manufacturing process to form a mirror array part in which a large number of micromirrors are two-dimensionally arranged on a semiconductor substrate such as silicon, and according to a control signal input from the outside. The angle of the reflection surface of each micromirror is changed.

Since the above exposure apparatus can directly expose a desired exposure pattern obtained by spatial light modulation of laser light with DMD onto a photosensitive material, a printed wiring board can be produced without preparing a light shielding mask or the like. (See Non-Patent Document 1 and Patent Document 1). In order to protect the mirror array part from external stimuli, the DMD is configured so that the mirror array part is accommodated in an internal sealed space. The DMD has a light transmission window portion made of a light transmission member for allowing laser light to enter the mirror array portion and for emitting laser light reflected by the mirror array portion from the DMD.
JP 2004-001244 A Akihito Ishikawa "Development shortening and mass production application by maskless exposure", "Electrotronics packaging technology", Technical Research Committee, Vol.18, No.6, 2002, p.74-79

  By the way, in response to demands for miniaturization of the wiring pattern of the printed wiring board and shortening of the exposure time, studies have been made to shorten the wavelength and increase the output of light used for exposure of the photosensitive material. That is, the line width of the wiring pattern can be reduced by improving the resolution by shortening the wavelength of the light, and the time for curing the photosensitive material can be shortened by increasing the output of the light.

  However, when light having a short wavelength, such as ultraviolet light, is used for exposure of the photosensitive material, suspended particles floating in the sealed space containing the mirror array portion of the DMD, for example, silicon generated in a semiconductor process for constructing a micromirror Suspended particles containing as a component are deposited in a region through which the light passes in a surface on the inner side (side facing the sealed space) of the light transmission window. When the fine particles are deposited on the surface of the light transmission window, when the light incident on the micromirror or the light reflected by the micromirror passes through the light transmission window, the light is reflected, scattered, Alternatively, there is a problem in that the quality of the wiring pattern is deteriorated due to blurring and a decrease in light amount in the wiring pattern that is absorbed and imaged on the photosensitive material. Further, as the wavelength of the light is shortened or the output is increased, the amount of the fine particles deposited increases and the problem of deterioration of the quality of the wiring pattern becomes more serious.

  The reason why the floating particles are deposited on the light transmission window is, for example, that the floating particles are irreversibly changed by a photochemical reaction and have a structure in which the surface tension is small and easily adhere to the glass surface. It is possible to deposit on the surface.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an exposure method and apparatus capable of suppressing a reduction in quality of an exposure pattern formed on a photosensitive material.

  The exposure method of the present invention includes a modulation element array unit in which a large number of modulation elements that modulate light having an ultraviolet or violet wavelength emitted from a light source are arranged two-dimensionally, and light comprising a transmission material that transmits the light. From the light source incident through the light transmission window portion, using a spatial light modulator having a transmission window portion and a sealing cover portion for sealing the modulation element array portion with the light transmission window portion An exposure method in which emitted light is spatially modulated by a modulation element array unit and emitted from the light transmission window, and the emitted light is imaged on a photosensitive material to expose the photosensitive material, When light emitted from a light source is incident on the spatial light modulator, heat is applied to the spatial light modulator to raise the temperature of the spatial light modulator.

The exposure method includes a mirror array unit in which a number of micromirrors that reflect and modulate light having a wavelength of ultraviolet or violet emitted from a light source are arranged in a two-dimensional manner, and light transmission comprising a transmission material that transmits the light. Using a DMD having a window portion and a sealing cover portion for sealing the mirror array portion with the light transmission window portion, light emitted from the light source incident through the light transmission window portion is generated. An exposure method in which the light is reflected by the mirror array part, spatially modulated and emitted from the light transmission window part, and the emitted light is imaged on the photosensitive material to expose the photosensitive material,
An exposure method, wherein when light emitted from the light source is incident on the DMD, heat is applied to the DMD to raise the temperature of the DMD.

  An exposure apparatus according to the present invention includes a light source that emits light having an ultraviolet or violet wavelength, a modulation element array section in which a large number of modulation elements that modulate the light are two-dimensionally arranged, and a transmission material that transmits the light. A light transmission window portion, and a sealing cover portion for sealing the modulation element array portion between the light transmission window portion and light emitted from the light source incident through the light transmission window portion. Spatial light modulator that spatially modulates light at the modulation element array part and emits the light from the light transmissive window part, and imaging optics that images the spatial light modulated light emitted through the light transmissive window part on the photosensitive material An exposure apparatus for exposing the photosensitive material, the apparatus comprising: a temperature adjusting means for increasing the temperature of the spatial light modulator by applying heat to the spatial light modulator. is there.

  The ultraviolet or violet wavelength may be 100 nm or more and 435 nm or less.

  The temperature adjusting means may adjust the temperature of the spatial light modulator to a temperature that is equal to or lower than a durable temperature of the spatial light modulator and near the durable temperature.

  The durable temperature of the DMD means a maximum temperature at which the DMD can be continuously operated in a normal state.

  The spatial light modulator has, as the modulation element, a micro mirror that reflects and modulates light emitted from all k light sources, and the modulation element array unit includes a large number of micro mirrors arranged in a two-dimensional manner. A DMD having a mirror array portion can be obtained.

  The “temperature below the endurance temperature of the spatial light modulator and in the vicinity of the endurance temperature” is preferably in the range from a temperature 10 ° C. lower than the endurance temperature to the endurance temperature, and 5 It is more desirable that the temperature range from a low temperature to a durable temperature.

  The light source may emit light having a wavelength of 100 nm or more and 420 nm or less.

  The inventor of the present application applies heat to the spatial light modulator when exposing the photosensitive material by spatially modulating light having an ultraviolet or purple wavelength with a spatial light modulator and irradiating the photosensitive material. Focusing on the fact that increasing the temperature of the modulator reduces the amount of particles deposited on the light transmission window when light emitted from the light source is incident on the spatial light modulator, leading to the present invention. It is a thing.

  According to the exposure method of the present invention, the light emitted from the light source is emitted from the light source to the spatial light modulator that spatially modulates the light incident through the transmission window by the modulation element array and emits the light from the light transmission window. When the incident light is incident, heat is applied to the spatial light modulator to raise the temperature of the spatial light modulator, so that the accumulation of suspended particles on the light transmission window is suppressed. Can do. In addition, according to the exposure apparatus of the present invention, the spatial light modulator that spatially modulates the light emitted from the light source and incident through the light transmission window portion by the modulation element array portion and emits the light from the light transmission window portion is heated. Is added to increase the temperature of the spatial light modulator, so that the temperature of the spatial light modulator can be increased when the light emitted from the light source is incident on the spatial light modulator. Similarly to the above, it is possible to suppress the accumulation of suspended particles on the light transmission window.

  That is, by increasing the temperature of the spatial light modulator, the temperature of the suspended particles increases and the suspended particles have high kinetic energy. Therefore, when the suspended particles come into contact with the glass surface, Because it leaves the glass surface against stabilization, the amount of suspended particles deposited on the light transmission window when light having an ultraviolet or violet wavelength is incident on the light transmission window of the spatial light modulator. Can be suppressed.

  As a result, the influence of reflection, scattering, and absorption by the particles deposited on the light transmission window portion of the light passing through the light transmission window portion can be suppressed, and the quality of the exposure pattern imaged on the photosensitive material can be reduced. The decrease can be suppressed.

  If the temperature control means is controlled to a temperature not higher than the endurance temperature of the spatial light modulator and close to the endurance temperature, the accumulation of suspended particles on the light transmission window can be more reliably performed. It is possible to suppress the deterioration of the quality of the exposure pattern formed on the photosensitive material.

  If the light source emits light having a wavelength of not less than 100 nm and not more than 420 nm, the amount of suspended particles deposited on the light transmission window is suppressed, and the quality of the exposure pattern imaged on the photosensitive material is reduced. The remarkable effect which suppresses can be acquired. That is, when the wavelength of the light source is shortened, the irreversible photochemical reaction is promoted, the number of particles having a characteristic that the surface tension is small and easily adheres to the glass surface increases, and the amount of suspended particles deposited further increases. The remarkable effect which suppresses accumulation of can be acquired.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a diagram showing an optical path of an optical system of an exposure head provided in the exposure apparatus, FIG. 2 is a perspective view showing a schematic configuration of the optical system, and FIG. 3 is a schematic configuration of a DMD and temperature adjusting means for applying heat to the DMD. 4 is an enlarged perspective view, FIG. 4 is an enlarged view showing a part of a large number of micromirrors arranged two-dimensionally, FIGS. 5A and 5B are diagrams showing the operation of the micromirrors, and FIG. (A) and FIG. 6 (B) are diagrams showing examples of use areas of the micromirrors in the mirror array section.

  An exposure apparatus for carrying out the exposure method of the present invention is used for producing a printed wiring board, and exposes a wiring pattern onto a printed wiring board material formed by laminating a photosensitive material on the board.

  The exposure head 166 of the exposure apparatus includes a light source 66 that emits light having an ultraviolet or violet wavelength, and a minute mirror 82 that is a modulation element having a variable tilt angle that reflects and modulates the light emitted from the light source 66 in a two-dimensional manner. A plurality of mirror array portions 81 arranged in a row, a light transmission window portion 87 made of a transmission material that transmits the light, and the mirror array portion 81 that is a modulation element array portion are sealed between the light transmission window portion 87. Spatial light modulator that has a sealing cover portion 88 for light, and that emits light emitted from the light source 66 that has entered through the light transmission window portion 87 is spatially modulated by the mirror array portion 81 and is emitted from the light transmission window portion. And an imaging optical system 5 that forms an image on the light-sensitive material 30K disposed on the surface of the printed wiring board material 30 with the DMD 80 and the light transmission window 87. When, and a temperature control means 90 to raise the temperature of the DMD 80 by applying heat to the DMD 80.

  The exposure head 166 is further emitted from a light intensity distribution correcting optical system 67 and a light intensity distribution correcting optical system 67 for correcting the light emitted from the light source 66 to be light having a substantially uniform intensity distribution. The mirror 69 that reflects the reflected light and changes the direction of the optical path, and the light beam reflected by the mirror 69 is totally reflected and incident on the DMD 80, and at the same time the TIR that transmits the spatial light modulated light emitted from the DMD 80 is transmitted. Total reflection) prism 70 is provided.

<< Description of each component constituting the exposure apparatus >>
<Light source 66>
The light source 66 includes a plurality of multiplexing units (not shown) that combine each laser beam emitted from a plurality of GaN-based semiconductor lasers emitting light having a wavelength of 405 nm into one multiplexing optical fiber. The laser light having a wavelength of 405 nm is emitted from an optical fiber bundle 66A formed by bundling a plurality of optical fibers for multiplexing of each multiplexing unit. The light emitted from the light source 66 is not limited to laser light having a wavelength of 405 nm, and may be any light as long as it is ultraviolet or violet light.

<Light intensity distribution correcting optical system 67>
As shown in FIG. 1, the light intensity distribution correcting optical system 67 includes a condenser lens 71 that condenses the laser light Le emitted from the optical fiber bundle 66A of the light source 66, and the laser light Le that has passed through the condenser lens 71. And a collimating lens 74 disposed downstream of the rod integrator 72, that is, on the mirror 69 side. The rod integrator 72 emits the laser beam Le incident on one end from the other end so that the light intensity distribution in the cross section of the light beam becomes more constant. As a result, the laser light Le emitted from the optical fiber bundle 66A and passed through the light intensity distribution correcting optical system 67 becomes a light beam whose light intensity distribution in the cross section of the light beam is substantially constant.

<DMD80>
The DMD 80 has a mirror array portion 81 disposed in a sealed space M (see FIG. 3) formed between the light transmission window portion 87 and the sealing cover portion 88. The light transmission window portion 87 is made of a glass member or a resin member that is transparent to the laser light Le. Further, the sealing cover portion 88 is formed of a metal material, a resin material, a ceramic material, or the like that is opaque to the laser light Le emitted from the light source 66.

  The mirror array unit 81 is configured by arranging a number of micromirrors 82 for constituting one pixel in a grid pattern (for example, 1024 × 768). In this apparatus, each micromirror 82 corresponds to each pixel of the wiring pattern exposed to the printed wiring board material 30, and each micromirror 82 is individually controlled based on the value of the data created for each pixel. . By this control, the laser light incident on each micromirror 82 is reflected in either the exposure direction toward the optical path for exposing the printed wiring board material 30 or the non-exposure direction deviating from this exposure direction, Only the laser light directed in the exposure direction is used for exposure of the photosensitive material 30K of the printed wiring board material 30 through a predetermined optical path. That is, a desired number of micromirrors 82 are controlled on the photosensitive material 30K so as to reflect the laser light in the exposure direction (ON) or reflect the laser light in the non-exposure direction (OFF). The wiring pattern is exposed.

  As shown in FIG. 4, the mirror array unit 81 is configured such that each micromirror (micromirror) 82 is supported by a support column on an SRAM cell (memory cell) 83. A large number (for example, 1024 × 768) of micromirrors constituting a pixel are arranged in a grid pattern. The surface of the micromirror 82 supported by the column corresponding to each pixel is deposited with a material having high reflectivity such as aluminum. Note that the reflectance of the micromirror 82 is 90% or more. A silicon gate CMOS SRAM cell 83 manufactured on a normal semiconductor memory manufacturing line is arranged directly below the micromirror 82 via a support including a hinge and a yoke, and the entire structure is monolithic. ing.

  When a digital signal is written in the SRAM cell 83 of the DMD 80, the micro mirror 82 supported by the support column is tilted within a range of ± α degrees (for example, ± 10 degrees) around the diagonal line of the micro mirror 82. FIG. 5A shows a state in which the micro mirror 82 is tilted to + α degrees when the micro mirror 82 is in the on state, and FIG. 5B shows a state in which the micro mirror 82 is tilted to −α degrees when the micro mirror 82 is in the off state. Therefore, by controlling the inclination of the micro mirror 82 in each pixel of the DMD 80 as shown in FIG. 5 according to the image signal, the laser light Le incident on the DMD 80 has a direction corresponding to the inclination of each micro mirror 82. That is, the light is reflected in the exposure direction and the non-exposure direction.

  The on / off control of the micro mirror 82 is performed by a controller 302 (described later) connected to the DMD 80. Further, the amount of laser light applied to the photosensitive material 30K of the printed wiring board material 30 can be controlled by changing the ratio of the time for turning on and turning off the micromirror per unit time. it can.

  Next, partial use of the mirror array unit 81 will be described. As shown in FIGS. 6A and 6B, in the mirror array portion 81, 1024 micro-pixels arranged in the main scanning direction at the time of exposure, that is, in the column direction, are arranged in the sub-direction at the time of exposure. Although 756 (pixel columns) are arranged in the scanning direction, that is, in the row direction, in this example, control is performed so that only a part of micromirror columns (eg, 1024 columns × 300 rows) is driven by the controller. The

  For example, as shown in FIG. 6A, it is possible to control only the matrix region 80C of the micromirrors 82 arranged at the center in the row direction of the 756 rows of the mirror array unit 81, as shown in FIG. As shown, only the matrix region 80T of the micromirrors 82 arranged at the end of the mirror array portion 81 in the row direction may be controlled. The data processing speed when controlling the DMD 80 is limited, and the modulation speed of each micromirror 82 decreases as the number of micromirrors to be controlled (number of pixels) increases. Can be used to increase the modulation speed of each micromirror 82 included in this portion.

<Temperature control means 90>
As shown in FIG. 3, the temperature adjustment means 90 includes a heating unit 91 for applying heat to the DMD 80, a thermistor 92 for measuring the temperature of the DMD 80, and the temperature of the DMD based on the temperature measured by the thermistor 92. And a controller 93 that controls the heating unit 91 so as to obtain a desired temperature. The temperature adjustment means 90 is for increasing the temperature of the DMD 80 by applying heat to the DMD 80 when the light emitted from the light source 66 is incident on the DMD 80. For example, the temperature is adjusted so that the temperature of the DMD 80 is equal to or lower than the durable temperature of the DMD 80 and near the durable temperature.

  The heating unit 91 applies heat to the DMD 80 in such a manner that the heating unit 91 and the DMD 80 are brought into contact with each other and the heat generated in the heating unit 91 is transmitted to the DMD 80 by heat conduction, or the heating unit 91 and the DMD 80 are connected. It is possible to adopt a method in which the heat generated in the heating unit 91 is transmitted to the DMD 80 by radiation without contact. In addition, as a method for generating heat in the heating unit 91, a conventionally known method can be adopted. For example, a resistance heating method in which a current flows through a conductor such as metal to generate heat, and a high-frequency wave is generated in the conductor. Adopting an induction heating method that induces eddy current to generate heat, a method that uses Peltier effect to transfer heat by flowing current between two kinds of metals in contact, or a method that circulates a heated fluid Can do. In addition, the system which controls the heating part 91 with the controller 93 can employ | adopt the system which increases / decreases the current supplied to the heating part 91, and a heating fluid, or turns it on / off.

<Imaging optical system 51>
As shown in FIG. 1, the imaging optical system 51 includes a first imaging optical system 51A including lens systems 52 and 54, a second imaging optical system including microlens array 55, aperture array 59, and lens systems 57 and 58. The system 51B is arranged in this order from the upstream side to the downstream side of the optical path. The microlens array 55 includes microlenses 55a that are reflected by the micromirrors 82 of the DMD 80 and that pass through the first imaging optical system 51A and that pass through the light beams corresponding to the micromirrors 82, respectively. It will be. As the microlens 55a, for example, a lens having a focal length of 0.19 mm and an NA (numerical aperture) of 0.11 can be used. The aperture array 59 includes a large number of apertures 59a formed corresponding to the microlenses 55a of the microlens array 55.

  The first imaging optical system 51A enlarges the image by the DMD 80 three times and forms an image in the microlens array 55. The second imaging optical system 51B enlarges the image formed in the microlens array 55 and forms the image on the photosensitive material 30K of the printed wiring board material 30. Therefore, the entire imaging optical system 51 enlarges the wiring pattern spatially modulated by the DMD 80 five times and forms an image on the photosensitive material 30K of the printed wiring board material 30.

  The printed wiring board material 30 is conveyed in the sub-scanning direction (a direction perpendicular to the paper surface of FIG. 1, the Y direction in the drawing) by a stage driving device described later.

<Operation of controlling temperature of DMD by temperature control means>
Here, the effect of adjusting the temperature of the DMD 80 by the temperature adjusting means 90 will be described.

  FIG. 7 shows the cumulative time (cumulative light irradiation time) in which the light emitted from the light source 66 is passed through the light transmission window 87 on the coordinates where the vertical axis indicates the ratio (ε) and the horizontal axis indicates the time (t). The ratio of the light intensity of the laser light emitted through the transmission window 87 during a specific cumulative light irradiation time to the light intensity of the laser light emitted through the transmission window 87 when the cumulative light irradiation time is 0 It shows the relationship.

  That is, with respect to the light intensity H (t = 0) of the laser light emitted from the light source 66 and emitted through the light transmission window 87, the minute mirror, and the light transmission window 87 at the cumulative light irradiation time t = 0. Ratio of light intensity H (t = tx) of laser light emitted from the light source 66 and emitted through the light transmission window portion 87, the minute mirror, and the light transmission window portion 87 at a specific cumulative light irradiation time t = tx. ε (ε = H (t = tx) / H (t = 0), hereinafter, the ratio ε is referred to as a light passage ratio ε).

  The light intensity was measured with all the micromirrors turned on and with the light quantity of light emitted from the light source 66 being a predetermined constant value. Further, when the cumulative light irradiation time is 0 (t = 0), the light passing ratio ε is 100%. At this time, when the laser light incident on the light transmission window 87 is reflected by the micromirror, the light passing ratio ε is about 100%. A loss of light amount of about 8% occurs when the light passes through the light transmission window 87 twice by 10%.

  When heat is not applied to the DMD 80 (indicated by the line J0 in the figure), the light passage ratio ε decreases greatly as the cumulative light irradiation time increases. This is because the suspended particles in the sealed space M are deposited on the inner surface of the light transmissive window 87 (on the side of the mirror array portion 81 or the side facing the sealed space M). This is due to increased light reflection, scattering, and absorption. When the progress of deposition of suspended particles is saturated, the light passage ratio ε converges to a substantially constant value P1.

  On the other hand, when heat is applied to the DMD 80 and the temperature of the DMD 80 is equal to or lower than the endurance temperature and close to the endurance temperature (indicated by the line J1 in the figure), the heat is not applied to the DMD 80. Since the progress of the accumulation of the floating particles inside the transmission window portion 87 is much slower, the degree of decrease in the light passing ratio value ε is small.

  Further, FIG. 8 shows each temperature when the DMD 80 is heated to a constant temperature by applying heat to the DMD 80 on the coordinate axis indicating the ratio (ε) on the vertical axis and the temperature (T) on the horizontal axis. It shows the relationship with the light passage ratio when the accumulated light irradiation time reaches a predetermined time, for example, 1000 hours (t = 1000) in a state where the temperature is adjusted to each temperature.

  As can be seen from the figure, the value ε of the light passage ratio increases as each set temperature (T) when the temperature of the DMD 80 is controlled to a constant temperature by the temperature control means 90 increases from the normal temperature To (for example, 20 ° C.). I understand that. This is because as the set temperature control of the DMD 80 by the temperature control means 90 becomes higher, the accumulation of suspended particles in the sealed space M inside the light transmission window portion 87 when the cumulative light irradiation time reaches 1000 hours. This is because the amount decreased. When the temperature of the DMD 80 is kept below the endurance temperature (for example, 50 ° C.) of the DMD 80 and in the vicinity of the endurance temperature (for example, 45 ° C. or more and 50 ° C. or less, the range indicated by the symbol Tw in the figure) The value ε is close to 100%.

<< Explanation of the entire exposure apparatus >>
Hereinafter, the entire exposure apparatus will be described. FIG. 9 is a perspective view showing the external appearance of the exposure apparatus, FIG. 10 is a perspective view showing how the photosensitive material is exposed using the exposure head, and FIG. 11A is a plan view showing an exposure area formed on the photosensitive material. FIG. 11B is a diagram showing the positional relationship of the exposure areas by each exposure head.

  The exposure apparatus 200 includes a flat moving stage 152 that sucks and holds the back surface of the printed wiring board material 30 (the surface opposite to the photosensitive material 30K). Two guides 158 extending along the stage moving direction are installed on the upper surface of the thick plate-shaped installation table 156 supported by the four legs 154. The stage 152 is arranged so that the longitudinal direction thereof faces the stage moving direction, and is supported by a guide 158 so as to be reciprocally movable. The exposure apparatus is provided with a stage driving device (not shown) that drives a stage 152 as a sub-scanning means along the guide 158 in the stage moving direction.

  A U-shaped gate 160 is provided at the center of the installation table 156 so as to straddle the movement path of the stage 152. Each of the ends of the U-shaped gate 160 is fixed to both side surfaces of the installation table 156. A plurality of (for example, two) sensors 164 for detecting the front and rear ends of the scanner 162 and the printed wiring board material 30 are respectively attached to the gate 160 and fixedly arranged above the moving path of the stage 152. . The scanner 162 and the sensor 164 are connected to a controller (not shown) that controls them.

  As shown in FIGS. 10 and 11B, the scanner 162 includes a plurality of (for example, 14) exposure heads 166 arranged in an approximately matrix of m rows and n columns (for example, 3 rows and 5 columns). . In this example, five exposure heads 166 are arranged in the first and second rows and four in the third row in relation to the width of the printed wiring board material 30. In addition, when showing each exposure head arranged in the m-th row and the n-th column, it is expressed as an exposure head 166mn.

  An exposure area 168 by the exposure head 166 has a rectangular shape with a short side in the sub-scanning direction. Accordingly, as the stage 152 moves, a strip-shaped exposed region 170 is formed for each exposure head 166 in the printed wiring board material 30. In addition, when showing the exposure area by each exposure head arranged in the mth row and the nth column, it is expressed as an exposure area 168mn.

  Further, as shown in FIGS. 11A and 11B, each of the exposure heads in each row arranged in a line so that the strip-shaped exposed regions 170 are arranged without gaps in the direction orthogonal to the sub-scanning direction. These are arranged with a predetermined interval (natural number times the long side of the exposure area, twice in this example) in the arrangement direction. For this reason, the part which cannot be exposed between the exposure area 16811 of the 1st line and the exposure area 16812 can be exposed by the exposure area 16821 of the 2nd line and the exposure area 16831 of the 3rd line.

  Each of the exposure heads 16611 to 166mn includes a DMD 80 that modulates the incident laser light for each pixel in accordance with image data. Each exposure head 166 is connected to a controller 302 (to be described later) including a data processing unit and a mirror drive control unit. This data processing unit generates a control signal for controlling each micromirror of the DMD 80 based on the input data indicating the wiring pattern. The mirror drive control unit turns on / off each micromirror of the DMD 80 based on the control signal generated by the data processing unit.

<< Explanation regarding electrical configuration of exposure apparatus >>
Next, the electrical configuration of the exposure apparatus 200 will be described. FIG. 12 is a block diagram showing the electrical configuration of the exposure apparatus.

  As shown in the figure, a modulation circuit 301 is connected to the overall control unit 300. The modulation circuit 301 acquires image data indicating a wiring pattern. A controller 302 that controls the DMD 80 is connected to the modulation circuit 301. Furthermore, an LD (Laser Diode) drive circuit 303 that drives a laser module disposed in the light source 66 is connected to the overall control unit 300. The overall controller 300 is connected to a stage driving device 304 that drives the stage 152.

<< Explanation of operation of exposure apparatus >>
Next, the operation of the exposure apparatus 200 will be described. Under the control of the controller 93 of the temperature adjusting means 90, heat is applied to the DMD 80 to maintain the temperature of the DMD 80, for example, at or below the durable temperature of the DMD 80 as described above.

  The light beams of the combined laser beams emitted from the GaN-based semiconductor lasers included in the light sources 66 of the exposure heads 166 of the scanner 162 are emitted from the end face of the optical fiber bundle 66A.

  When the wiring pattern is exposed, the image data is input from the modulation circuit 301 to the controller 302 of the DMD 80 and temporarily stored in the frame memory of the controller 302.

  The stage 152 that has attracted the printed wiring board material 30 to the surface thereof moves at a constant speed from the upstream side to the downstream side along the guide 158 by the drive of the stage driving device 304. When the front end of the printed wiring board material 30 is detected by the sensor 164 attached to the gate 160 when the stage 152 passes under the gate 160, the wiring pattern stored in the frame memory is created. The image data is read by the data processing unit of the controller 302, and the data processing unit generates a control signal for each exposure head 166 based on the image data. Then, the mirror drive control unit performs on / off control of each micromirror of the DMD 80 for each exposure head 166 based on the generated control signal. In the case of this example, the size of the micromirror is 14 μm × 14 μm.

  When laser light emitted from the light source 66 is incident on the DMD 80, the light beam reflected by the micro mirror 82 when the micro mirror 82 of the DMD 80 is in the on state passes through the imaging optical system 51 and is printed on the printed wiring board material 30. An image is formed on the photosensitive material 30K, and each exposure area 168 on the photosensitive material 30K is exposed. Further, by moving the printed wiring board material 30 together with the stage 152 at a constant speed in the stage moving direction, the printed wiring board material 30 is sequentially exposed in the sub-scanning direction opposite to the stage moving direction. A strip-shaped exposed region 170 for each exposure head 166 is formed on 30K.

  When the exposure to the printed wiring board material 30 by the scanner 162 is completed and the sensor 164 detects the rear end of the printed wiring board material 30, the stage 152 gates along the guide 158 by driving the stage driving device 304. The origin returns to the most upstream side of 160 and can be used for the next exposure.

  In this way, by performing exposure in a state where the temperature of the DMD 80 is increased by applying heat to the DMD 80, accumulation of suspended particles in the sealed space M on the light transmission window 87 can be suppressed, and light transmission can be suppressed. Since an increase in reflection, scattering, and absorption of laser light at the window can be suppressed, it is possible to suppress a decrease in quality of the exposure pattern formed on the photosensitive material.

  In the present embodiment, the light source used in the exposure apparatus 200 is a GaN-based semiconductor laser. However, for example, a solid laser, a gas laser, or the like can be used. Specifically, a laser combining a YAG laser having a wavelength of approximately 355 nm and SHG, a laser combining a YLF laser having a wavelength of approximately 355 nm and SHG, a laser combining a YAG laser having a wavelength of approximately 266 nm and SHG, and an excimer laser having a wavelength of approximately 248 nm An excimer laser having a wavelength of about 193 nm can also be employed. Further, instead of a laser light source, a mercury lamp or the like can be adopted as the light source.

  The above exposure method is not limited to the case of exposing a wiring pattern, but can be applied to the case of exposing any pattern or image.

  In the above embodiment, an exposure method has been described in which a photosensitive material is exposed using a DMD having a mirror array portion in which a number of micromirrors are two-dimensionally arranged as a spatial light modulator. This is not always the case. That is, the spatial light modulator includes a modulation element array section in which a large number of modulation elements that modulate ultraviolet or violet light emitted from a light source are arranged in a two-dimensional manner, and a transmission material that transmits the light. A spatial light modulator having a light transmission window portion and a sealing cover portion for sealing the modulation element array portion with the light transmission window portion can be employed. In such a case, the light emitted from the light source incident through the light transmission window portion is spatially modulated by the modulation element array portion and emitted from the light transmission window portion, and the emitted light is emitted from the light transmission window portion. Is imaged on the photosensitive material to expose the photosensitive material.

The figure which shows the optical path of the optical system of the exposure head with which the exposure apparatus of embodiment of this invention is provided The perspective view which shows schematic structure of the optical system of exposure head Enlarged perspective view showing schematic configuration of DMD and temperature control means for applying heat to DMD The figure which expands and shows a part of many micromirrors arranged in two dimensions Diagram showing the operation of a micromirror The figure which shows the example of the use area of the minute mirror in the mirror array The figure which shows the relationship between accumulation light irradiation time and light passage ratio The figure which shows the relationship between each temperature when DMD80 is temperature-controlled, and the light passage ratio when reaching predetermined | prescribed cumulative light irradiation time in each temperature A perspective view showing the appearance of the exposure apparatus The perspective view which shows a mode that a photosensitive material is exposed using an exposure head FIG. 11A is a plan view showing an exposure area formed on the photosensitive material, and FIG. 11B is a view showing the positional relationship of the exposure area by each exposure head. It is a block diagram which shows the electric constitution of exposure apparatus.

Explanation of symbols

30 Printed Wiring Board Material 30K Photosensitive Material 51 Imaging Optical System 66 Light Source 80 DMD
DESCRIPTION OF SYMBOLS 81 Mirror array 82 Micro mirror 87 Light transmission window part 88 Sealing cover part 90 Temperature control means 166 Exposure head 200 Exposure apparatus Le Laser light

Claims (5)

A modulation element array section in which a large number of modulation elements that modulate ultraviolet or violet wavelengths emitted from a light source are arranged in a two-dimensional manner, a light transmission window section made of a transmission material that transmits the light, and the modulation Using a spatial light modulator having a sealing cover portion for sealing an element array portion with the light transmission window portion, the light emitted from the light source incident through the light transmission window portion is modulated. An exposure method for exposing the photosensitive material by performing spatial light modulation in the element array unit and emitting the light from the light transmission window, and forming an image of the emitted light on the photosensitive material,
An exposure method characterized in that when light emitted from the light source is incident on the spatial light modulator, heat is applied to the spatial light modulator to raise the temperature of the spatial light modulator. A light source that emits light having an ultraviolet or violet wavelength;
A modulation element array section in which a large number of modulation elements for modulating the light are two-dimensionally arranged, a light transmission window section made of a transmission material that transmits the light, and the modulation element array section with the light transmission window section A sealing cover portion for sealing between them, and the light emitted from the light source incident through the light transmission window portion is spatially modulated by the modulation element array portion and emitted from the light transmission window portion; A spatial light modulator;
An exposure apparatus that exposes the photosensitive material, the imaging optical system comprising: an imaging optical system that forms an image on the photosensitive material of the spatially light-modulated light emitted through the light transmission window;
An exposure apparatus comprising temperature adjusting means for applying heat to the spatial light modulator to increase the temperature of the spatial light modulator. The temperature control means adjusts the temperature of the spatial light modulator to a temperature not higher than the endurance temperature of the spatial light modulator and in the vicinity of the endurance temperature. Exposure equipment. 4. The exposure apparatus according to claim 2, wherein the light source emits light having a wavelength of not less than 100 nm and not more than 420 nm.   The spatial light modulator has, as the modulation element, a micromirror that reflects and modulates light emitted from the light source, and the modulation element array unit includes a plurality of micromirrors arranged in a two-dimensional manner. 5. The exposure apparatus according to claim 2, wherein the exposure apparatus is a DMD having a mirror array section.

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