Light irradiation device and exposure device

Abstract

In a light irradiation device that combines laser beams generated using a plurality of laser sources into a single beam and emits the combined beam, the light irradiation device suppresses the dissipation of light emitted from the plurality of laser sources without causing an increase in the optical path length. In the light irradiation device and the exposure device of the present invention, an illumination optical system has: an incidence angle conversion unit including a first lens and a second lens arranged so as to form a positional relationship of a beam expander; a divided lens unit having a plurality of lenses arranged in a direction perpendicular to the optical axis of the incidence angle conversion unit and along the plane, the divided lens unit dividing the light emitted from the incidence angle conversion unit by means of the plurality of lenses; an optical path length difference generation unit that has a plurality of light-transmitting units that have different optical path lengths and are arranged in a direction perpendicular to the optical axis, and that causes the light that has passed through the plurality of lenses to enter the plurality of light-transmitting units, respectively; and a condenser lens unit that overlaps an irradiation region of the light emitted from the plurality of light-transmitting units on a surface to be irradiated.

Description

Technical Field

[0001] The present invention relates to a technology for exposing a substrate to draw a pattern on a substrate such as a semiconductor substrate, a semiconductor package substrate, a printed wiring substrate, or a glass substrate. Background Art

[0002] As a technology for forming patterns such as wiring patterns on a substrate, there is a technology that exposes the photosensitive layer formed on the surface of the substrate by incident light beams modulated according to exposure data. As the substrate, various substrates such as semiconductor substrates, printed wiring substrates, semiconductor packaging substrates, and glass substrates can be applied. For example, in Patent Document 1, a drawing device for drawing a substrate by modulating a laser beam (line beam) having a flat beam spot using a light modulator and causing it to be incident on the substrate, and a light irradiation device used as its light source are disclosed. In this technology, in order to generate a high-intensity line beam with a uniform intensity distribution, lasers emitted from multiple laser light sources (laser diodes) are synthesized to generate a single line beam.

[0003] Specifically, multiple laser light sources configured to emit light in the same plane are emitted toward one point in the plane. A split lens, an optical path length difference generating unit, a focusing lens, etc. are sequentially arranged on the optical path. Through the action of these optical systems, a linear beam is generated that takes the direction parallel to the above-mentioned plane as the length direction and expands the reduced linear beam in the direction perpendicular to the plane. The optical path length difference generating unit is provided to suppress interference generated when laser light as coherent light is synthesized.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 6383166 Summary of the invention

[0007] Problems to be solved by the invention

[0008] When further increasing the light intensity, for example, it is considered to increase the number of laser light sources. In such a case, the components of light incident on the split lens at a large incident angle become more. Therefore, the light emitted from the split lens and incident on the optical path length difference generating unit also has various angle components. In this way, the light incident on the split lens and the optical path length generating unit at a large angle sometimes emerges from the side of these optical elements. Due to the dispersion of such light, the intensity of the final line beam cannot be fully improved, and its uniformity is also impaired.

[0009] In order to avoid this problem, it is necessary to suppress the diffusion angle of the light incident on the split lens to be small. For example, it is considered to increase the distance between the light source and the split lens. However, in this case, the total length of the optical path becomes longer, and there is a problem of large-scale device.

[0010] Means for solving problems

[0011] The present invention has been completed in view of the above-mentioned problems, and its purpose is to provide a technology that can suppress the dispersion of light emitted from multiple laser light sources without increasing the optical path length in a light irradiation device that combines laser beams generated by multiple light sources into a single light beam and emits it, and an exposure device using the light irradiation device.

[0012] The light irradiation device of the present invention comprises: a plurality of laser light sources arranged so that the center lines of the emitted light are mutually included in the same plane and intersect at one point in the plane; and an illumination optical system which synthesizes the laser light emitted from the plurality of laser light sources to generate a single laser beam and irradiates the single laser beam to a surface to be irradiated. Furthermore, the illumination optical system comprises: an incident angle conversion unit which includes a first lens and a second lens, the first lens being arranged at a position where the light emitted from the plurality of laser light sources is incident, and the second lens being arranged so as to form a positional relationship of a beam expander with the first lens; a splitting lens unit which has a plurality of lenses arranged in a direction perpendicular to the optical axis of the incident angle conversion unit and along the plane, and splits the light emitted from the incident angle conversion unit by the plurality of lenses; an optical path length difference generating unit which has a plurality of light-transmitting units having different optical path lengths and arranged in a direction perpendicular to the optical axis, and causes the light passing through the plurality of lenses to be incident on the plurality of light-transmitting units respectively; and a focusing lens unit which overlaps the irradiation areas of the light emitted from the plurality of light-transmitting units on the surface to be irradiated.

[0013] In the invention thus constituted, an incident angle conversion unit is provided between a plurality of laser light sources that emit light from various directions in a single plane toward one point in the plane and a split lens unit. In the incident angle conversion unit, the first lens and the second lens are configured to form a positional relationship of a beam expander. Generally, a beam expander is used to make collimated light incident along its optical axis to expand or reduce the beam diameter of the collimated light. On the other hand, since the laser is incident on the incident angle conversion unit of the present invention from various directions, the light is also incident from a direction that is inclined relative to the optical axis.

[0014] By setting such a structure, the diffusion angle of the light incident on the split lens can be reduced compared with the case where the incident angle conversion unit is not provided, and the details will be described later. That is, the incident angle conversion unit has the function of reducing the incident angle of the light emitted from each laser light source when it is incident on the split lens. In this way, the incident angle conversion unit can achieve the same effect as increasing the distance between the laser light source and the split lens without increasing the actual distance.

[0015] Therefore, the effect of suppressing the escape of light from the split lens and the optical path length difference generating section by reducing the incident angle of light incident on the split lens can be achieved without increasing the optical path length.

[0016] In addition, the incident angle conversion unit also functions as a beam expander. Therefore, a beam having a spot size corresponding to the size of the split lens can be generated based on the beam emitted from each laser light source, and the beam can be incident on the split lens. Therefore, the light can be uniformly incident on the multiple lenses constituting the split lens.

[0017] Effects of the Invention

[0018] As described above, according to the present invention, an incident angle conversion unit composed of two lenses is provided on the optical path from the plurality of laser light sources to the split lens, thereby preventing light from escaping due to light entering the split lens at a large incident angle without increasing the optical path length.

[0019] The above and other objects and novel features of the present invention will become more fully apparent from the following detailed description with reference to the accompanying drawings, which are provided for illustration only and do not limit the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a front view schematically showing the general structure of the exposure apparatus of the present invention.

[0021] Figure 2 Yes means Figure 1 A block diagram of an example of an electrical structure of an exposure device.

[0022] Figure 3 It is a diagram showing a schematic structure of a light irradiation unit.

[0023] Figure 4 This is a diagram schematically showing an example of a detailed structure of the exposure head.

[0024] Figure 5A It is a diagram showing a schematic structure of a laser emitting section.

[0025] Figure 5B It is a diagram showing a schematic structure of a laser emitting section.

[0026] Figure 6 A ray diagram showing the overall structure of an illumination optical system and the optical path of a light beam.

[0027] Fig. 7A It is a diagram showing a more detailed structure of the incident angle conversion unit and its function.

[0028] Figure 7BIt is a diagram showing a more detailed structure of the incident angle conversion unit and its function.

[0029] Fig. 8A 3 is a ray diagram showing light passing through the split lens and the optical path length difference generating unit.

[0030] Figure 8B 3 is a ray diagram showing light passing through the split lens and the optical path length difference generating unit.

[0031] Fig. 9 1 is a diagram showing the relationship between the light incident on the incident angle conversion unit and the light incident on the split lens. DETAILED DESCRIPTION

[0032] Figure 1 1 is a front view schematically showing the general structure of the exposure device of the present invention. Figure 2 It is shown Figure 1 A block diagram showing an example of an electrical structure of an exposure device. Figure 1 In the following figures, the X direction as the horizontal direction, the Y direction as the horizontal direction orthogonal to the X direction, the Z direction as the vertical direction, and the rotation direction θ around the rotation axis parallel to the Z direction are appropriately shown.

[0033] The exposure device 1 irradiates a substrate S (exposure target substrate) with a layer of photosensitive material such as a resist with a laser beam of a predetermined pattern, thereby drawing a pattern on the photosensitive material. As the substrate S, various substrates such as semiconductor package substrates, printed wiring substrates, glass substrates for various display devices, and semiconductor substrates can be applied.

[0034] The exposure device 1 includes a main body 11, and the main body 11 is composed of a main frame 111 and a cover plate (not shown) attached to the main frame 111. Various components of the exposure device 1 are arranged inside and outside the main body 11.

[0035] The interior of the main body 11 of the exposure device 1 is divided into a processing area 112 and a delivery area 113. The processing area 112 is mainly provided with a workbench 2, a workbench driving mechanism 3, an exposure unit 4, and an alignment unit 5. In addition, an illumination unit 6 for supplying illumination light to the alignment unit 5 is arranged outside the main body 11. A conveying device 7 such as a conveying robot for carrying in and out the substrate S relative to the processing area 112 is arranged in the delivery area 113. Furthermore, a control unit 9 is arranged inside the main body 11. The control unit 9 is electrically connected to each part of the exposure device 1 and controls the operation of each part.

[0036] The conveying device 7 disposed in the delivery area 113 inside the main body 11 receives an unprocessed substrate S from an external conveying device or substrate storage device (not shown) and carries (loads) the unprocessed substrate S into the processing area 112. In addition, the processed substrate S is carried out (unloaded) from the processing area 112 and sent to the outside. The loading of the unprocessed substrate S and the unloading of the processed substrate S are performed by the conveying device 7 according to the instruction from the control unit 9.

[0037] The workbench 2 has a flat plate-like shape and holds the substrate S placed on its upper surface in a horizontal position. A plurality of suction holes (not shown) are formed on the upper surface of the workbench 2, and negative pressure (suction pressure) is applied to the suction holes. Thus, the substrate S placed on the workbench 2 is fixed to the upper surface of the workbench 2. The workbench 2 is driven by a workbench driving mechanism 3.

[0038] The table driving mechanism 3 is an XYZ-θ driving mechanism that moves the table 2 in the Y direction (main scanning direction), the X direction (sub-scanning direction), the Z direction, and the rotation direction θ (yaw direction). The table driving mechanism 3 includes: a Y-axis robot 31 that is a single-axis robot extending in the Y direction; a stage 32 driven in the Y direction by the Y-axis robot 31; an X-axis robot 33 that is a single-axis robot extending in the X direction on the upper surface of the stage 32; a stage 34 driven in the X direction by the X-axis robot 33; and a θ-axis robot 35 that drives the table 2 supported on the upper surface of the stage 34 in the rotation direction θ relative to the stage 34.

[0039] Therefore, the table drive mechanism 3 can drive the table 2 in the Y direction by the Y-axis servo motor of the Y-axis robot 31, drive the table 2 in the X direction by the X-axis servo motor of the X-axis robot 33, and drive the table 2 in the rotation direction θ by the θ-axis servo motor of the θ-axis robot 35. The servo motors are not shown in the figure. Figure 1 The Z-axis robot 37 (not shown) drives the worktable 2 in the Z direction. The worktable driving mechanism 3 operates the Y-axis robot 31, the X-axis robot 33, the θ-axis robot 35, and the Z-axis robot 37 according to the command from the control unit 9, thereby moving the substrate S placed on the worktable 2.

[0040] The exposure unit 4 includes an exposure head 41 disposed above the substrate S on the workbench 2, and a light irradiation unit 40 including a light source driving unit 42, a laser emitting unit 43, and an illumination optical system 44 for irradiating the exposure head 41 with laser light. A plurality of exposure units 4 may be provided at different positions in the X direction.

[0041] The laser light emitted from the laser emitting section 43 by the operation of the light source driving section 42 is irradiated to the exposure head 41 via the illumination optical system 44. The exposure head 41 modulates the laser light irradiated from the light irradiation section by a spatial light modulator (hereinafter sometimes simply referred to as "light modulator") 410, and irradiates the laser light to the substrate S moving directly below the exposure head 41. By exposing the substrate S with the laser beam in this way, a pattern is drawn on the substrate S (exposure operation).

[0042] The alignment unit 5 has an alignment camera 51 disposed above the substrate S on the workbench 2. The alignment camera 51 has a lens barrel, an objective lens, and a CCD image sensor, and photographs alignment marks provided on the upper surface of the substrate S moving directly below the alignment camera 51. The CCD image sensor provided in the alignment camera 51 is composed of, for example, an area image sensor (two-dimensional image sensor).

[0043] The lighting unit 6 is connected to the lens barrel of the alignment camera 51 via the optical fiber 61, and supplies illumination light to the alignment camera 51. The illumination light guided by the optical fiber 61 extending from the lighting unit 6 is guided to the upper surface of the substrate S via the lens barrel of the alignment camera 51, and the reflected light on the substrate S is incident on the CCD image sensor via the objective lens. Thus, the upper surface of the substrate S is photographed to obtain a captured image. The alignment camera 51 is electrically connected to the control unit 9, obtains a captured image according to an instruction from the control unit 9, and sends the captured image to the control unit 9.

[0044] The control unit 9 acquires the position of the alignment mark represented by the captured image captured by the alignment camera 51. In addition, the control unit 9 controls the exposure unit 4 based on the position of the alignment mark, thereby adjusting the pattern of the laser irradiated from the exposure head 41 to the substrate S during the exposure operation. Then, the control unit 9 irradiates the substrate S with the laser modulated according to the pattern to be drawn from the exposure head 41, thereby drawing the pattern on the substrate S.

[0045] The control unit 9 realizes various processing by controlling the actions of the above-mentioned units. For this purpose, the control unit 9 includes a CPU (Central Processing Unit) 91, a memory (RAM) 92, a storage device 93, an input unit 94, a display unit 95, and an interface unit 96. The CPU 91 reads and executes a control program 931 pre-stored in the storage device 93, and performs various actions described later. The memory 92 is used for the calculation processing of the CPU 91, or for short-term storage of data generated as a result of the calculation processing. The storage device 93 stores various data and control programs for a long time. Specifically, the storage device 93 is a non-volatile storage device such as a flash memory storage device and a hard disk drive device. In addition to the control program 931 executed by the CPU 91, the storage device 93 also stores, for example, design data representing the content of the pattern to be drawn, that is, CAD (Computer Aided Design) data 932.

[0046] The input unit 94 receives operation input from the user, and for this purpose, has a keyboard, a mouse, a touch panel, or other appropriate input device (not shown). The display unit 95 notifies the user by displaying and outputting various information, and for this purpose has an appropriate display device, such as a liquid crystal display panel. The interface unit 96 is responsible for communication with external devices. For example, when the exposure device 1 receives the control program 931 and the CAD data 932 from the outside, the interface unit 96 functions. For this purpose, the interface unit 96 may also have a function for reading data from an external recording medium.

[0047] The CPU 91 executes the control program 931. Thus, functional blocks such as the exposure data generation unit 911, the exposure control unit 912, the focus control unit 913, and the stage control unit 914 are realized by software. In addition, at least a part of each of these functional blocks may be realized by dedicated hardware.

[0048] The exposure data generating unit 911 generates exposure data for modulating the light beam according to the pattern based on the CAD data 932 read from the storage device 93. When the substrate S is deformed by strain or the like, the exposure data generating unit 911 corrects the exposure data according to the amount of strain of the substrate S, thereby enabling drawing that matches the shape of the substrate S. The exposure data is sent to the exposure head 41, and the exposure head 41 modulates the laser light emitted from the light irradiation unit 40 according to the exposure data. In this way, the modulated light beam modulated according to the pattern is irradiated to the substrate S, and the surface of the substrate S is partially exposed to draw the pattern.

[0049] The exposure control unit 912 controls the light irradiation unit 40 to emit a laser beam having a predetermined optical power and spot size. The focus control unit 913 controls a projection optical system (described later) provided in the exposure head 41 to focus the laser beam on the surface of the substrate S.

[0050] The stage control unit 914 controls the stage drive mechanism 3 to realize the movement of the stage 2 for alignment adjustment and the movement of the stage 2 for scanning movement during exposure. In the alignment adjustment, the position of the stage 2 is adjusted in the X direction, the Y direction, the Z direction, and the θ direction so that the relative position relationship between the substrate S placed on the stage 2 and the exposure head 41 at the start of exposure becomes a predetermined relationship. On the other hand, in the scanning movement, the main scanning movement of moving the stage 2 in the Y direction at a constant speed so that the substrate S passes under the exposure head 41 and the stepping feeding in the X direction at a constant pitch (sub-scanning movement) are combined.

[0051] Figure 3 4 is a diagram showing a schematic structure of the light irradiation unit. The light irradiation unit 40 includes optical elements such as an incident angle conversion unit 441, a split lens 442, an optical path length difference generation unit 443, a condenser lens 444, and a projection optical system 414 as other main components of the above-mentioned laser emitting unit 43 and the spatial light modulator 410. The incident angle conversion unit 441, the split lens 442, the optical path length difference generation unit 443, and the condenser lens 444 constitute the illumination optical system 44 as a whole.

[0052] The laser beam emitted from the laser emitting section 43 is incident on the split lens section 442 via the incident angle conversion section 441, and then incident on the optical path length difference generating section 443. As described later, the light emitted from the optical path length difference generating section 443 becomes a light beam having a flat spot shape with the horizontal direction (X direction) as the long axis direction. The light beam is further converged in the short axis direction by the condenser lens 444 to become a line beam, which is incident on the spatial light modulator 410 of the exposure head 41. The light emitted from the spatial light modulator 410 is a light beam modulated by exposure data, which is irradiated to the substrate S on the workbench 2 via the projection optical system 411.

[0053] The detailed structure of the illumination optical system 44 will be described later. Here, the structure of the exposure head 41 in the light irradiation unit 40 will be described first.

[0054] Figure 4 FIG. 1 is a diagram schematically showing an example of a detailed structure of an exposure head. Figure 4As shown, a spatial light modulator 410 having a diffractive optical element 411 is provided in the exposure head 41. Specifically, the spatial light modulator 410, which is mounted on the upper part of a support column 400 extending in the vertical direction (Z direction) in the exposure head 41, is supported by the support column 400 via a movable table 412 in a state where the reflective surface of the diffractive optical element 411 faces downward.

[0055] In the exposure head 41, the diffractive optical element 411 is arranged so that the normal line of its reflection surface is inclined with respect to the traveling direction of the incident light beam L. The light emitted from the illumination optical system 44 is incident on the reflection mirror 413 through the opening of the support 400, and is reflected by the reflection mirror 413 and irradiated to the diffractive optical element 411. Then, the control unit 9 switches the state of each channel of the diffractive optical element 411 according to the exposure data, and modulates the laser beam L incident on the diffractive optical element 411.

[0056] The laser light reflected from the diffractive optical element 411 as the 0th order diffraction light is incident on the lens of the projection optical system 414. On the other hand, the laser light reflected from the diffractive optical element 411 as the 1st order or higher diffraction light is not incident on the lens of the projection optical system 414. That is, basically only the 0th order diffraction light reflected by the diffractive optical element 411 is incident on the projection optical system 414. The diffractive optical element 411 is configured so that the 0th order diffraction light is emitted in the (-Z) direction. As the diffractive optical element 411, for example, a GLV (Grating Light Valve; "GLV" is a registered trademark of Silicon Photonics Inc.) element can be appropriately applied.

[0057] The light that has passed through the lens of the projection optical system 414 is converged by the focusing lens 415 and guided to the substrate S at a predetermined magnification as an exposure light beam traveling in the (-Z) direction, that is, downward. The projection optical system 414 constitutes a reduction optical system. The focusing lens 415 is mounted on a focusing drive mechanism 416. Then, according to a control instruction from the focus control unit 913 of the control unit 9, the focusing drive mechanism 416 raises and lowers the focusing lens 415 in the vertical direction (Z-axis direction). As a result, the convergence position of the exposure light beam emitted from the focusing lens 415 is adjusted to the upper surface of the substrate S.

[0058] like Figure 4As shown in the optical path of the laser beam L indicated by the single-dot chain line in FIG. 4 , the laser beam L guided from the light irradiation unit 40 to the exposure head 41 has a beam spot shape that is uniformly elongated in the X direction with the X direction as the major axis direction and the Z direction as the minor axis direction. On the other hand, the modulated laser beam Lm modulated by the light modulator 410 has the X direction as the major axis direction and the Y direction as the minor axis direction, and the light intensity distribution in the X direction is modulated according to the exposure data. Furthermore, the exposure beam Le emitted from the projection optical system 414 toward the substrate S is obtained by reducing the modulated laser beam Lm in the X direction and the Y direction. The exposure beam Le with the reduced spot size is made incident on the exposure surface of the substrate S, so that a fine pattern can be drawn on the surface of the substrate S.

[0059] While the exposure light beam Le modulated according to the exposure data is incident on the substrate S, the exposure head 41 and the substrate S are relatively moved in the Y direction. Thus, a strip-shaped area of ​​the substrate S having a width equal to the spot size of the exposure light beam Le in the X direction and extending in the Y direction can be exposed. Exposure is repeated while sequentially changing the relative position of the exposure head 41 and the substrate S in the X direction, so that the entire substrate S can be exposed in the end.

[0060] In this way, by combining the scanning movement in the Y direction and the scanning movement in the X direction between the exposure head 41 and the substrate S, the entire substrate S can be depicted. In this specification, the scanning movement in the Y direction is referred to as "main scanning movement", and the Y direction is referred to as "main scanning direction". On the other hand, the scanning movement in the X direction is referred to as "sub-scanning movement", and the X direction is referred to as "sub-scanning direction". In this embodiment, the scanning movement is realized by moving the worktable 2 supporting the substrate S relative to the fixed exposure head 41.

[0061] The exposure units 4 having the above-described structure can be provided in multiple positions in the X direction. In this embodiment, five sets of exposure units 4 having the same structure are provided, and they emit exposure light beams Le in parallel to perform drawing, thereby improving the throughput of drawing processing. In addition, these exposure units 4 can operate independently of each other, but the scanning movement relative to the substrate S is unified in structure.

[0062] Next, the configurations of the laser emitting unit 43 and the illumination optical system 44 in the light irradiation unit 40 will be described.

[0063] Figure 5A and Figure 5B 43 is a diagram showing a schematic structure of a laser emitting unit. Figure 5A as well as Figure 5B As shown, several approaches can be considered. Figure 5A The laser emitting section 43a of the illustrated configuration example includes a plurality of light source units 430a. In this example, seven sets of light source units 430a are used, but the number of light source units to be arranged is not limited thereto and is arbitrary.

[0064] Each light source unit 430a includes a laser light source 431 for emitting laser light, a collimating lens 432, and a focusing lens 433. The laser light source 431 is, for example, a laser diode that outputs laser light of a predetermined wavelength. The collimating lens 432 converts the laser light emitted from the laser light source 431 into collimated light. The focusing lens 433 focuses the collimated laser light and emits it as a convergent beam.

[0065] As shown by the dashed lines in the figure, each light source unit 430a is configured so that its output light beams intersect at one point. Specifically, each light source unit 430a is configured so that the center lines of the output light shown by the dashed lines move along the same XY plane and intersect at a point Pa in the XY plane.

[0066] On the other hand, Figure 5B In the laser emitting portion of the structural example shown, a light source unit 430b having a laser light source 431, a collimating lens 432, and a focusing lens 433 is provided, which is the same as the above structural example. Each laser light source 431 emits laser light in the same direction (in this example, the Y direction) in the same XY plane. That is, the laser light emitted from each laser light source 431 is parallel to each other.

[0067] A wedge prism 434 (4341 to 4347) is provided on each optical path. The (+Y) side end surface of each wedge prism 4341 to 4347 is set to be tilted relative to the XZ plane so that the respective emitted light intersects at a point Pb on the XY plane. The amount of error of the laser light emitted from each laser light source 431 deviating from parallelism can be adjusted by moving the condenser lens 433 and the wedge prism 434 in the Y direction. In this way, the offset relative to a point Pb on the XY plane can be eliminated.

[0068] As the laser emitting unit 43, any one of the two structural examples 43a and 43b described above can be appropriately applied. Therefore, in the following description, they are not particularly distinguished and are described as "laser emitting unit 43". In addition, even if the structure illustrated in the figure corresponds to any one of the structural examples 43a and 43b described above, this is just an example, and another structural example can be applied instead without any problem.

[0069] In addition, from the perspective of component manufacturing, the laser light sources 431 are arranged in a row and in a straight line. Figure 5B Especially when there are a large number of laser light sources 431, it is necessary to arrange the laser light sources 431 at appropriate angles. Figure 5A In the structure, the adjustment operation may become complicated. In addition, when a water cooling mechanism is provided to cool the light source, a structure in which the laser light sources 431 are arranged in a straight line is also advantageous. In addition, the arrangement of each laser light source 431 in the XY plane is preferably symmetrical with respect to the optical axis of the illumination optical system 44.

[0070] Figure 6 It is a ray diagram that shows the overall structure of the illumination optical system and the optical path of the light beam. More specifically, Figure 6 The structures of the illumination optical system 44 in the XY plane and the YZ plane are shown. Figure 6 When the light diagram is shown in the following figures, some of the light rays are omitted for easy viewing of the drawings. Figure 6 Only the light emitted from one in the center and two at both ends of the light emitted from the seven groups of laser light sources 431 are shown.

[0071] The illumination optical system 44 includes the above-mentioned main components, namely, the incident angle conversion unit 441, the split lens 442, the optical path length difference generation unit 443, and the condenser lens 444, and further includes a Z-direction collimating lens 445, a Z-direction diffusion lens 446, a Z-direction condenser lens 447, etc. These optical elements are arranged so that their optical axes coincide with each other. Figure 6 The optical axis is represented by a single-dot chain line.

[0072] The multiple laser beams emitted from the laser emitting section 43 are incident on the incident angle conversion section 441 provided near the intersection thereof. Specifically, a collimating lens 445 is provided on the front side of the intersection, that is, on the side close to the laser emitting section 43, and the light beams passing through the lens 445 are incident on the incident angle conversion section 441. The collimating lens 445 is, for example, a cylindrical lens having no optical power in the X direction but having optical power in the Z direction. Therefore, the laser beam is collimated in the Z direction.

[0073] In the incident angle conversion unit 441, a concave lens 4411 is arranged at a position closer to the front side than the intersection of the laser beams and capable of causing all the laser beams emitted from the laser light sources 430 to be incident. The concave lens 4411 has optical power in the X direction but has no optical power in the Z direction. In addition, a convex lens 4412 is arranged behind the concave lens 4411 in the optical path of the laser beam. As described below, the convex lens 4412 is arranged at a position where a beam expander is formed between the concave lens 4411 and the concave lens 4411 relative to the concave lens 4411.

[0074] Fig. 7A and Figure 7B FIG. 4 is a diagram showing a more detailed structure and function of the incident angle conversion unit. Fig. 7AWhen f1 represents the focal length of the concave lens 4411 and f2 represents the focal length of the convex lens 4412, the two lenses are Fig. 7A That is, the convex lens 4412 is configured so that the front focal position thereof coincides with the focal position of the concave lens 4411.

[0075] Such a combination of lenses corresponds to a structure called a so-called Galilean beam expander. A beam expander is generally used to enlarge (or reduce) the beam diameter of collimated light incident along the optical axis. On the other hand, in this embodiment, Fig. 7A As shown in the light diagram, light is incident from the laser irradiation unit 43 relative to the concave lens 4411 from multiple directions, and the incident direction is not necessarily along the optical axis.

[0076] Under such conditions, light incident on the concave lens 4411 at a relatively large diffusion angle is temporarily diffused by the concave lens 4411 and then focused by the convex lens 4412. As a result, the diffusion angle of the outgoing light is smaller than that of the incident light. This suppresses the light with a diffusion angle from being incident on the split lens 442. That is, the incident angle conversion unit 441 has the function of reducing the size of the diffusion of the incident light when observed from the split lens 442 and quantitatively reducing the maximum incident angle of the incident light relative to the split lens 442.

[0077] return Figure 6 The illumination optical system 44 is further described. The structures of the split lens 442 and the optical path length difference generating unit 443 are the same as those described in Patent Document 1. That is, the split lens (compound eye lens) 442 has a plurality of lenses 4421 arranged perpendicular to the optical axis and in the X direction, and the light emitted from the incident angle conversion unit 441 is split by the plurality of lenses 4421. On the other hand, the optical path length difference generating unit 443 has a plurality of light-transmitting units arranged in a direction perpendicular to the optical axis and having mutually different optical path lengths, so that the light passing through the split lens 442 is incident on the plurality of light-transmitting units respectively. These structures and functions are described in detail in Patent Document 1 (Japanese Patent Gazette No. 6383166), so the description is omitted here. In short, as a whole, they split the incident light beam into a plurality of light beams arranged at a constant pitch in the X direction, and have the function of adjusting their optical path lengths.

[0078] Fig. 8A and Figure 8B : is a ray diagram showing the light passing through the split lens and the optical path length difference generating unit. Fig. 8A In the example shown, light incident from the (-Y) side end face of the split lens 442 is emitted from the (+Y) side end face of the split lens 442 and the (+Y) side end face of the optical path length difference generating unit 443. Figure 8BIn the example shown, part of the light incident on the optical path length difference generating unit 443 is emitted from the side thereof, and is scattered without reaching the (+Y) side end surface. Such light scattering occurs when the maximum incident angle of the light incident on the split lens 442 is large. Such light scattering reduces the light intensity as a whole and reduces the uniformity of the light intensity in the X direction.

[0079] When the number of laser light sources 431 is increased to increase the light intensity, the incident angle of light from the laser light sources 431 arranged at the end to the split lens 442 is inevitably increased due to the structure of arranging them in the X direction. In other words, the diffusion angle of the incident light to the split lens 442 is increased.

[0080] By providing the incident angle conversion unit 441 between the laser emitting unit 43 and the split lens 442, the diffusion angle of the incident light relative to the split lens 442 can be suppressed to be smaller and closer to parallel light. As a result, the dispersion of light caused by the diffusion of the incident light can be suppressed. As an example, consider the case where light with a maximum inclination of about 9 degrees relative to the optical axis is incident on the incident angle conversion unit 441. At this time, if a concave lens 4411 with f1=-11 mm and a convex lens 4412 with f2=100 mm are used, light with a maximum inclination of about 1 degree relative to the split lens 443 can be incident from the incident angle conversion unit 441.

[0081] In addition, the incident angle conversion unit 441 has a function of converting the light from the plurality of laser light sources 431 as a whole into light close to parallel light, and also has a function of making the X-direction spot size of the light beam formed by the light as a whole consistent with a light beam of a size suitable for the split lens 442. That is, the incident angle conversion unit 441 has a function of making the light equally incident on the plurality of lenses 4421 constituting the split lens 442. This can be said to be a function of a beam expander capable of appropriately enlarging or reducing the spot size of the incident light beam.

[0082] In terms of suppressing the diffusion angle of the incident light, the same effect can be obtained by increasing the distance between the laser emitting unit 43 and the split lens 442 and reducing the incident angle. In this case, the optical path length becomes longer, so it is inevitable that the overall size of the illumination optical system 44 becomes larger. The incident angle conversion unit 441 of this embodiment is more preferable in that the incident angle can be reduced without extending the optical path length.

[0083] In addition, as a beam expander, in addition to the above-mentioned Galilean beam expander, there is also a Keplerian beam expander composed of two convex lenses. As the incident angle conversion unit 441, such a Keplerian beam expander can also be applied. Figure 7BAs shown, a convex lens 4413 is arranged at a position where the plurality of light beams emitted from the laser emitting unit 43 can be incident on the rear of the intersection point of the plurality of light beams emitted from the laser emitting unit 43. The convex lens 4413 has optical power at least in the X direction.

[0084] Furthermore, the other convex lens 4414 is arranged so that its front focal position becomes the rear focal position of the convex lens 4413. The convex lens 4414 has optical power at least in the X direction. Figure 7B In FIG. 4 , symbols f1 and f2 represent the focal lengths of convex lenses 4413 and 4414, respectively. In this way, a Kepler type beam expander is formed. Even with such a structure, Figure 7B As shown in the light ray diagram, the light emitted from the laser emitting portion 43 can also be incident on the split lens 442 at a relatively large diffusion angle as light with a smaller diffusion angle.

[0085] As follows Fig. 7A , Figure 7B The structures shown are compared. Fig. 7A The structure shown has the following advantages: if the lens magnification is the same, the optical path length can be shortened, and since the light beam is not converged, it is not easily affected by dust on the optical path. Figure 7B The structure shown can be realized by a combination of convex lenses, and is a structure that converges light beams between the lenses, and therefore has the advantage of being easier to adjust.

[0086] In addition, in the incident angle conversion unit 441, in order to set the magnification (or reduction) ratio of the light beam between the incident light and the outgoing light to a desired value, it is necessary to determine the configuration of the two lenses according to their respective focal lengths so as to meet the constituent requirements of a Galilean or Keplerian beam expander. On the other hand, for the purpose of only adjusting the diffusion angle of the light beam, a certain degree of variation is allowed for the configuration of the lenses. That is, the configuration of the two lenses may not strictly meet the requirements of the beam expander.

[0087] In addition, it is considered that the purpose of adjusting the divergence angle of the light beam can be roughly achieved even with a single concave lens. However, as described below, in the incident angle conversion based on a single lens, a good result may not always be obtained.

[0088] By properly setting the lens characteristics, even a single concave lens can convert the incident light into light close to parallel light and suppress the diffusion angle. However, in reality, if you want to suppress the diffusion of light after passing through the concave lens, you cannot make the curvature of the lens surface too large. Therefore, the ratio of the spot size of the incident light beam to the spot size of the outgoing light beam may not become larger. The individual light beams emitted from the laser emitting portion 43 are incident on the split lens 442 without being magnified. In this case, the individual beam spots are generally small enough compared to the diameters of the individual lenses that constitute the split lens 442. Therefore, it is difficult to achieve the purpose of making the light uniformly incident on each lens.

[0089] Therefore, in this embodiment, the principle of a beam expander combining two lenses is used. Such a structure is excellent in the effect of incident angle conversion (reduction of diffusion angle) and its controllability. In addition, by appropriately selecting the lens magnification, the adjustment of the spot size is also easy.

[0090] Return again Figure 6 The light beam emitted from the optical path length difference generating unit 443 enters the Z-direction diffusion lens 446. The Z-direction diffusion lens 446 is a concave lens having no optical power in the X direction but having optical power in the Z direction. Therefore, the light beam diffused in the Z direction is emitted from the Z-direction diffusion lens 446.

[0091] The light beam is incident on the image plane via the focusing lens 444 and the Z-direction focusing lens 447. The image plane in this case is the light receiving surface of the diffractive optical element 414. The focusing lens 444 is a convex lens having optical power in both the X-direction and the Z-direction, so that the light beam converges on the image plane. As a result, the multiple light beams arranged along the X-direction emitted from the split lens 442 overlap on the image plane. Since these light beams are coherent light, interference will occur when they overlap. The optical path length difference generating unit 443 avoids the occurrence of interference by making a difference in the optical path length of each light beam.

[0092] On the other hand, in the Z direction, the light beam temporarily expanded by the Z-direction diffusion lens 446 is greatly reduced by the two condenser lenses 444 and 447. As a result, a linear light beam L ( ) which is flat in the X direction and has uniform intensity and a small diffusion in the Z direction is incident on the image plane (diffractive optical element 414). Figure 4 ).like Figure 4 As shown, the line beam L is modulated by the diffractive optical element 414 of the spatial light modulator 410. The modulated beam Lm is reduced by the projection optical system 414 and irradiated onto the substrate S as the exposure beam Le.

[0093] Next, refer to Fig. 9 The optical characteristics required of the incident angle conversion unit 441 will be described. Fig. 9 is a diagram showing the relationship between the incident light to the incident angle conversion unit and the incident light to the split lens. Fig. 9 As shown, the maximum incident angle allowed for the incident light to the split lens 442 is represented by symbol θ1. Here, the maximum incident angle θ1 is the maximum value of the incident angle at which the light incident to the split lens 442 is emitted from the optical path length difference generating unit 443 without being scattered. That is, in order to prevent the light from being scattered, the incident angle of the incident light to the split lens 442 needs to be less than the maximum incident angle θ1. The maximum incident angle θ1 depends on the diameter and length of each lens constituting the split lens 442 and the length of the optical path length difference generating unit 443.

[0094] In order to make the incident angle of the light incident from the incident angle conversion unit 441 to the split lens 442 equal to or less than the maximum incident angle θ1, the incident angle θ0 of the light incident to the incident angle conversion unit 441 should satisfy the following condition:

[0095] θ1≥1 / |f2 / f1|×θ0=|f1 / f2|×θ0 … (Formula 1)

[0096] Or, it can be expressed as the following transformed formula:

[0097] θ0≤|f2 / f1|×θ1…(Formula 2).

[0098] When the equality is established, the allowable value of the incident angle from the laser irradiation unit 43 to the incident angle conversion unit 441 can be maximized. It is sufficient to set the focal lengths f1 and f2 of the two lenses 4411 and 4412 so as to meet this condition and obtain a suitable magnification (or reduction) factor that can make the light spot size evenly incident on each lens constituting the split lens 442. In the figure, the symbol F represents the focus of the two lenses 4411 and 4412.

[0099] As described above, in this embodiment, the laser beams emitted from the plurality of laser light sources 431 arranged in the X direction are overlapped with each other by the illumination optical system 44. In this way, a line beam L having a flat beam spot shape with the X direction as the major axis direction is generated. An incident angle conversion unit 441 is provided between the plurality of laser light sources 431 and the split lens 442 to reduce the incident angle to the split lens 442.

[0100] Thus, even when a large number of laser light sources 431 are arranged and the diffusion angle of the light emitted from them becomes large, the incident angle to the split lens 442 can be suppressed to be small. Thus, in this embodiment, the light beam emitted from the laser light source 431 can be reliably guided to the end surface of the split lens 442 and the light path length difference generating unit 443 on the emission side (+Y side), and the light is prevented from escaping from the side. As a result, a line beam with high intensity and uniform intensity distribution can be generated.

[0101] The incident angle conversion unit 441 can be realized by a combination of a concave lens 4411 and a convex lens 4412 having the same optical axes, or a combination of a convex lens 4413 and a convex lens 4414. The two lenses are arranged in a positional relationship that satisfies the conditions for forming a beam expander. By using such an optical system under the condition that light is also incident from a direction inclined relative to the optical axis, the diffusion of the outgoing light, that is, the incident angle to the rear stage can be made smaller than the incident angle of the incident light to the optical system.

[0102] In addition, the incident angle conversion unit 441 has a function as a beam expander, and can make the light adjusted to an appropriate spot size incident on the subsequent split lens 442. Therefore, the light can be uniformly incident on each lens 4421 constituting the split lens 442. By synthesizing the emitted light from them, the light amount distribution in the long axis direction of the finally generated line beam can be made uniform.

[0103] As described above, in the exposure device 1 of the present embodiment, the light irradiation unit 40 functions as the "light irradiation unit" of the present invention, the spatial light modulator 410 functions as the "light modulator" of the present invention, the projection optical system 414 functions as the "projection optical system" of the present invention, and the control unit 9 functions as the "control unit" of the present invention. In addition, the light irradiation unit 40 is equivalent to the "light irradiation device" of the present invention.

[0104] In the above embodiment, the illumination optical system 44 including the laser light source 431, the incident angle conversion unit 441, the split lens 442, the optical path length difference generation unit 443, and the condenser lens 444 functions as the "illumination optical system" of the present invention. In addition, the collimating lens 445 and the diffusion lens 446 function as the "collimating lens" and the "diffusion lens" of the present invention, respectively.

[0105] In the incident angle conversion unit 441, the concave lens 4411 and the convex lens 4413 correspond to the "first lens" of the present invention, while the convex lenses 4412 and 4414 correspond to the "second lens" of the present invention. The XY plane in the above embodiment corresponds to the "plane" of the present invention.

[0106] In addition, the present invention is not limited to the above-mentioned embodiment, and various changes can be made in addition to the above-mentioned contents as long as they do not deviate from the main purpose. For example, in the above-mentioned embodiment, the number of laser light sources 431 in the laser emitting unit 43 is 7, but it is not limited to this. When there are a small number of laser light sources, the diffusion of light can be suppressed to a small extent, so the incident angle conversion unit is not necessarily required, but when the number of laser light sources increases, the present invention is particularly effective.

[0107] In addition, in order to further improve the intensity of the light beam, it is considered to configure multiple laser light sources in the Z direction. As a structural example in such a case, it is considered to use an appropriate optical system to synthesize the light from multiple laser light sources arranged in the Z direction into one light beam along the XY plane, and then synthesize multiple such light beams in the XY plane. In such a case, by treating each light beam synthesized in the Z direction in the same way as the output light beam from each laser output unit 43 in the above-mentioned embodiment, a structure in which the present invention is applied can also be considered.

[0108] In the above-mentioned embodiment, as the "light modulator" of the present invention, the GLV element which is a one-dimensional diffractive optical element can be appropriately applied, but other light modulators can also be applied as the light modulator. For example, a two-dimensional diffractive optical element, a DMD (Digital Micro mirror Device) element which arranges a large number of fine mirrors to control reflection, etc. can be used as the light modulator.

[0109] In addition, the exposure device 1 of the above-mentioned embodiment has a built-in light irradiation unit 40 corresponding to the "light irradiation device" of the present invention, but the single light irradiation unit 40 can also be considered as an embodiment of the present invention. For example, the present invention can be implemented by replacing the light irradiation unit in the existing exposure device with the light irradiation unit of the present embodiment, or improving the light irradiation unit 40 of the present embodiment.

[0110] As described above with reference to specific embodiments, the incident angle conversion unit of the light irradiation device of the present invention can be realized as a combination of a first lens and a second lens by any one of a concave lens and a convex lens or a convex lens and a convex lens. As a combination of a concave lens and a convex lens, a so-called Galileo-type beam expander structure can be applied. In addition, as a combination of a convex lens and a convex lens, a so-called Kepler-type beam expander structure can be applied. Through any of these, the incident angle of light to the split lens unit can be reduced, and the light can be suppressed from escaping from the split lens unit and the optical path length difference generating unit.

[0111] In addition, for example, the first lens may not have optical power in the direction orthogonal to the plane. The incident angle conversion unit is provided for the purpose of adjusting the incident angle in the direction along the above-mentioned plane, and may not have any effect in the direction orthogonal to the plane. Therefore, the design of the optical system in the direction along the plane and the direction orthogonal to the plane can be independently performed, and the degree of freedom of design becomes high.

[0112] In addition, for example, the arrangement of the plurality of laser light sources can be symmetrical with respect to the optical axis in a plane. By making the light incident on the first lens at an angle with respect to the optical axis enter from a direction symmetrical with respect to the optical axis, the uniformity of the light in the plane can be improved.

[0113] In addition, for example, a collimating lens having optical power in a direction orthogonal to the plane may be arranged between the laser light source and the incident angle conversion unit. According to such a structure, it is possible to suppress the diffusion of light in a direction orthogonal to the plane, and to reliably guide the outgoing light from the laser light source to the incident angle conversion unit and the split lens unit.

[0114] In this case, for example, a diffusion lens having optical power in a direction orthogonal to the plane may be arranged between the optical path length difference generating unit and the focusing lens. According to such a structure, by temporarily diffusing the light in a direction orthogonal to the plane in front of the focusing lens, the light can be finally largely focused in a direction orthogonal to the plane.

[0115] In addition, when the diffusion angle of the emitted light from the plurality of laser light sources observed from the first lens is set to θ1, the maximum value of the incident angle of the light incident on the split lens portion and capable of passing through the optical path length difference generating portion is set to θ0, the focal length of the first lens is set to f1, and the focal length of the second lens is set to f2, the following relationship holds:

[0116] θ1≥|f1 / f2|×θ0.

[0117] In this way, the light incident from the laser light source can be emitted from the emission end of the optical path length difference generating unit without dissipating. In the above formula, the equal sign indicates the condition that θ0 becomes the maximum value allowed as the incident angle of light to the first lens. In other words, when the maximum incident angle θ0 from multiple laser light sources is predetermined, the dissipation of the subsequent light can be suppressed by selecting the first lens and the second lens in a manner that satisfies the above formula.

[0118] The invention has been described above according to specific embodiments, but the description is not intended to be interpreted in a limiting sense. With reference to the description of the invention, various modifications of the disclosed embodiments are obvious to those skilled in the art, as are other embodiments of the invention. Therefore, within the scope of the true scope of the invention, it can be considered that the scope of the attached patent claim includes the modification or embodiment.

[0119] Industrial Applicability

[0120] The present invention is applicable to the technical field of exposing a substrate to form a pattern on a substrate such as a semiconductor substrate, a semiconductor package substrate, a printed wiring substrate, or a glass substrate.

[0121] Explanation of symbols

[0122] 1Exposure device,

[0123] 2 workbenches,

[0124] 9. Control Department,

[0125] 40 light irradiation part,

[0126] 44Illumination optical system,

[0127] 410 spatial light modulator (optical modulator),

[0128] 414 projection optical system,

[0129] 431 laser light source,

[0130] 441 incident angle conversion unit,

[0131] 442 split lens (split lens portion),

[0132] 443 optical path length difference generating unit,

[0133] 444 focusing lens,

[0134] 445 collimating lens,

[0135] 446 diffusion lens,

[0136] 4411 concave lens (first lens),

[0137] 4412 convex lens (second lens),

[0138] 4413 convex lens (first lens),

[0139] 4414 convex lens (second lens),

[0140] L laser beam,

[0141] Le exposure beam,

[0142] S substrate.

Claims

1. A light irradiation device, characterized in that: have: A plurality of laser light sources are arranged so that center lines of emitted light are contained in the same plane and intersect at a point in the plane; and an illumination optical system that combines the laser beams emitted from the plurality of laser light sources to generate a single laser beam and irradiates the single laser beam onto the irradiated surface, The illumination optical system comprises: An incident angle conversion unit, comprising a first lens and a second lens, wherein the first lens is arranged at a position where the light emitted from the plurality of laser light sources is incident, and the second lens is arranged to form a positional relationship of a beam expander with the first lens; a split lens section having a plurality of lenses arranged in a direction perpendicular to the optical axis of the incident angle conversion section and along the plane, and splitting the light emitted from the incident angle conversion section by the plurality of lenses; an optical path length difference generating unit having a plurality of light-transmitting units having different optical path lengths and arranged in a direction perpendicular to the optical axis, and causing the light having passed through the plurality of lenses to be incident on the plurality of light-transmitting units respectively; and A condenser lens unit overlaps an irradiation area of ​​the light emitted from the plurality of light-transmitting units on the irradiated surface.

2. The light irradiation device according to claim 1, characterized in that The first lens is a concave lens, and the second lens is a convex lens.

3. The light irradiation device according to claim 1, characterized in that The first lens and the second lens are convex lenses.

4. The light irradiation device according to any one of claims 1 to 3, characterized in that: The first lens has no optical power in a direction orthogonal to the plane.

5. The light irradiation device according to any one of claims 1 to 3, characterized in that: The plurality of laser light sources are arranged symmetrically with respect to the optical axis within the plane.

6. The light irradiation device according to any one of claims 1 to 3, characterized in that: A collimator lens having optical power in a direction orthogonal to the plane is arranged between the laser light source and the incident angle conversion unit.

7. The light irradiation device according to claim 6, characterized in that A diffusion lens having optical power in a direction orthogonal to the plane is arranged between the optical path length difference generating unit and the condenser lens.

8. The light irradiation device according to any one of claims 1 to 3, characterized in that: When the diffusion angle of the emitted light from the plurality of laser light sources observed from the first lens is set to θ1, the maximum value of the incident angle of the light incident on the split lens unit and capable of passing through the optical path length difference generating unit is set to θ0, the focal length of the first lens is set to f1, and the focal length of the second lens is set to f2, the following relationship holds: θ1≥|f1 / f2|×θ0.

9. An exposure device for drawing a predetermined pattern by exposing the surface of a substrate, characterized in that: The exposure device comprises: a light irradiation unit having the same structure as the light irradiation device according to claim 1; A light modulator, which is arranged at the position of the illuminated surface; a control unit that controls the light modulator based on exposure data indicating a pattern to be drawn, thereby modulating the laser beam; as well as A projection optical system causes the modulated laser beam to be incident on the substrate.

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