JP2007208015A - Crystallization device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust the image formation position of laser beams speedily to undulations at a substrate side in a crystallization device. <P>SOLUTION: The crystallization device 1 comprises an optical system 2 including an illumination optical system 2b for applying laser beams, an optical modulation element 2c for modulating laser beams into rays having prescribed light intensity distribution, and an image-forming optical system 2d for forming the modulation light of the optical modulation element on a substrate; and a substrate stage 3 for supporting a substrate, thus melting a thin film provided on the substrate by modulation light for crystallization. The crystallization device has an image-forming optical system actuator 8 for adjusting a position in the Z-axis direction of the image-forming optical system 2d. The image-forming optical system actuator 8 adjusts the image formation position of the modulation light formed by the image-forming optical system 2d, by adjusting the position in the Z-axis direction of the image-forming optical system 2d. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a crystallization apparatus that melts and crystallizes an amorphous or polycrystalline semiconductor thin film using light.

  There is a technique for crystallizing an amorphous semiconductor layer formed on an insulator such as a glass substrate to obtain a crystalline semiconductor layer, and forming a thin film transistor (TFT) using the crystalline semiconductor layer as an active layer. Are known.

  For example, in an active matrix liquid crystal display device, a semiconductor film such as a silicon film is provided, a thin film transistor is formed on a glass substrate, and the thin film transistor is used as a switching element for switching display.

  The formation of a thin film transistor includes a crystallization step of a non-single-crystal semiconductor thin film such as an amorphous or polycrystalline film. As this crystallization technique, for example, a laser crystallization technique is known in which an irradiation region of a non-single-crystal semiconductor thin film is melted and crystallized using a short pulse laser beam with high energy.

  Currently, a laser crystallization apparatus used for production employs a technique of irradiating amorphous silicon with a laser beam having a long beam (for example, 500 μm × 300 mm) shape and a uniform intensity distribution. However, with this method, the crystal grain size of the obtained semiconductor film is as small as 0.5 μm or less. Therefore, a crystal grain boundary exists in the channel region of the TFT, and there is a limit in performance such as suppression of the TFT characteristics.

  In order to improve the performance of the TFT, a technique for manufacturing a high-quality semiconductor film having large crystal grains is required. As a crystallization method that satisfies this requirement, among various laser crystallization techniques, non-single-crystal semiconductor thin film is irradiated with an excimer laser beam with a reverse peak pattern-like light intensity distribution formed by phase modulation. As a result, crystallization technology (Phase Modulated Excimer Laser Annealing: PMELA) has attracted attention.

  The PMELA technique is a method of irradiating an excimer laser beam having a predetermined light intensity distribution onto a non-single crystal semiconductor thin film, melting the irradiated portion of the semiconductor film, and crystallizing. Excimer laser light having a predetermined light intensity distribution is obtained by phase-modulating incident laser light with a phase modulation element such as a phase modulation element such as a phase shifter. The non-single crystal semiconductor thin film is, for example, an amorphous silicon or polycrystalline silicon thin film formed on a glass substrate.

  The currently developed PMELA technology melts and crystallizes a region with a size of several mm square by one irradiation. By this crystallized non-single crystal semiconductor thin film treatment, a crystallized silicon thin film having a relatively uniform crystal grain size of several μm to 10 μm is formed (for example, see Non-Patent Document 1). ). TFTs fabricated on crystallized silicon thin films formed by this technique have been shown to have excellent electrical properties.

This PMELA crystallization technique has excellent characteristics that the use efficiency of laser light is high and crystals having a large particle diameter can be obtained. However, in order to obtain stable electrical characteristics, it is necessary to position crystal grains. To crystallize a large-area semiconductor film, a so-called step-and-repeat irradiation method is used. After the light irradiation, an irradiation method is used in which the glass substrate is moved to the next irradiation position, stopped, and then repeatedly irradiated with laser light.
Hiroaki Inoue, Mitsuru Nakada, Masayoshi Matsumura; Transactions of the Institute of Electronics, Information and Communication Engineers Vol.J85-C, No.8, pp.624-629, 2002 New 2-D Position Control Large Grain Formation Method ”

  In PMLA crystallization, the beam profile of the modulated light of the laser light irradiated on the substrate is required to be constant for each irradiation.

  On the other hand, the irradiated side irradiated with laser light has a variation in height due to the undulation of the glass substrate for liquid crystal provided with the semiconductor thin film and the variation of the flatness of the stage. The height of this undulation is, for example, about 20 μm to 50 μm. On the other hand, the depth margin (DOF) of the focal position of the laser beam is 5 μm to 20 μm, depending on the light modulation element. Thus, D.D. O. Since F does not have a sufficient width compared to the variation in height on the irradiated side, the undulation in the height direction of the substrate is represented by D.F. O. It is difficult to allow it by F. Therefore, in order to maintain a beam profile with a certain crystallization quality, the stage moves to the next irradiation position, and the height in the Z-axis direction at that irradiation position needs to be adjusted before the laser beam is irradiated. There is.

  Conventionally, this height adjustment in the Z-axis direction is performed by a Z-axis stage that moves in the Z-axis direction to a substrate stage that supports the substrate.

  FIG. 12 is a diagram for explaining a schematic configuration of the crystallization apparatus.

  The crystallization apparatus 10 includes a laser light source 2a that emits laser light, an illumination optical system 2b that irradiates the laser light, and a light modulation element that modulates the laser light irradiated by the illumination optical system 2b into a light beam having a predetermined light intensity distribution. 2c, an imaging optical system 2d that forms an image of the modulated light of the light modulation element 2c on the substrate (the substrate to be processed 20), and a two-dimensional position on the substrate (the substrate to be processed 20) that supports the substrate to be processed 20 The substrate stage 3 is defined. The modulated light applied to the substrate (target substrate 20) through the imaging optical system 2d melts and crystallizes the thin film provided on the substrate.

  The illumination optical system 2b, the light modulation element 2c, and the imaging optical system 2d constitute the optical system 2. The illumination optical system 2b constitutes an excimer illumination optical system, and emits and adjusts crystallization laser light that illuminates the light modulation element 2c.

  The substrate stage 3 includes an X-axis stage 3a, a Y-axis stage 3b, and a Z-axis stage 3c, and adjusts the height in the Z-axis direction of the substrate 20 to be processed placed on the stage by the Z-axis stage 3c. The height of the substrate to be processed 20 is adjusted to the image forming position. This height adjustment is performed by detecting the height of the substrate 20 to be processed by the substrate height detection unit 4 and driving the Z-axis stage 3c by a control signal obtained by processing this detection signal by the arithmetic circuit 7. Do.

  However, since this substrate stage usually has a weight of several hundred kg, high-speed Z-axis operation (for example, response speed of 10 msec or less) cannot be performed. A high-speed operation requires a substrate stage that has a torque that can move a heavy object up and down at a high speed and that can be positioned with high accuracy. A precision Z stage with such characteristics is known. Not.

  Currently, high-speed crystallization processing is required as the substrate size increases. In this high-speed processing, it is required to shorten the laser light irradiation period to shorten the laser light shot interval and to move the substrate at a high speed. However, as described above, the stage mechanism capable of high-speed Z-axis adjustment is as follows. It does not exist and is a factor that hinders the speeding up of crystallization.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described conventional problems and to adjust the imaging position of laser light at high speed with respect to the undulation on the substrate side in the crystallization apparatus.

  In the present invention, the imaging optical system for imaging the laser beam is configured to be movable in the Z-axis direction, thereby adjusting the imaging position of the laser beam at high speed. The imaging optical system, for example, weighs several kilograms and is extremely light compared to a substrate stage of several hundred kilograms, so that the imaging position of laser light can be adjusted at high speed. By adjusting the imaging position at a high speed, the crystallization of the substrate can be accelerated, and the throughput of the substrate due to the crystallization can be increased.

  The crystallization apparatus of the present invention includes an illumination optical system that irradiates laser light, a light modulation element that modulates the laser light into a light beam having a predetermined light intensity distribution, and an image of the modulated light of the light modulation element formed on a substrate. The crystallization apparatus includes an optical system including an image optical system and a substrate stage that supports the substrate, and melts and crystallizes a thin film provided on the substrate with modulated light.

  In this crystallization apparatus, the present invention includes an imaging optical system driving unit that adjusts the position of the imaging optical system in the Z-axis direction. The imaging optical system drive unit adjusts the imaging position of the modulated light imaged by the imaging optical system by adjusting the position in the Z-axis direction of the imaging optical system.

  For example, a high-speed piezo stage can be used as the imaging optical system driving unit. The high-speed piezo stage can have characteristics such as a stroke of 50 μm or more and a response time including a settling time of 10 msec or less. When the height of the imaging position is adjusted for each irradiation of the laser beam, the response time of the high-speed piezo stage is set to 10 msec or less, so that the shot period of the laser beam can be set to 100 Hz and high-speed operation can be achieved. It becomes possible.

  The crystallization apparatus of the present invention includes a substrate height detection unit that detects the height of the substrate in the Z-axis direction. The imaging optical system drive unit adjusts the position of the imaging optical system in the Z-axis direction based on the substrate height detected by the substrate height detection unit.

  The imaging optical system driving unit performs step driving at the same periodic intervals as the laser light irradiation, aligns the laser light with the irradiation position at a predetermined period, and irradiates the laser light from the optical system.

  The first aspect of the height adjustment by the imaging optical system drive unit of the present invention is to detect the height of the irradiation position in the Z-axis direction in the irradiation of the laser beam, and use the detected height for the laser. In the light irradiation period, the height of the imaging position in the Z-axis direction is adjusted, and after the adjustment is completed, laser light is emitted.

  The substrate height detection unit detects the substrate height in the Z-axis direction of the irradiation position where the laser beam is irradiated on the substrate, and the imaging optical system drive unit detects the substrate height detected by the substrate height detection unit. To adjust the imaging position. The imaging optical system driving unit has a response time, and a delay time occurs between the start of driving and the movement to a designated height.

  Therefore, in the first aspect, the response time causes a positional shift by an amount corresponding to the response time between the irradiation position detected by the substrate height detection unit and the irradiation position irradiated with the laser beam. At the same time, there is a possibility that a difference in height occurs between the irradiation position of the laser beam and the substrate.

  However, the height displacement that occurs at the intervals of the laser light irradiation positions is sufficiently small against the waviness of the substrate and the variation in the flatness of the substrate stage, so the height at the adjacent irradiation positions is high. By adjusting the height, the position of the imaging position can be controlled at high speed within the depth of focus.

  The second aspect of the height adjustment by the imaging optical system drive unit of the present invention is to detect the height of the irradiation position in the Z-axis direction in the irradiation of the laser beam, and use the detected height to The height of the imaging position in the Z-axis direction is adjusted at the laser light irradiation position.

  The substrate height detecting unit detects the substrate height in the Z-axis direction of the irradiation position where the laser beam is irradiated onto the substrate, and the imaging optical system driving unit is detected by the substrate height detecting unit one cycle ago. The imaging position is adjusted using the substrate height.

  In the second aspect, unlike the irradiation position detected by the substrate height detection unit and the irradiation position irradiated with the laser light, the height at the previous irradiation position is used in the stepwise irradiation of the laser light. Adjust the height of the next irradiation position.

  Due to the waviness of the substrate and the unevenness of the flatness of the substrate stage, the height displacement caused by the interval between the laser light irradiation positions is sufficiently small, so the height is adjusted to the height at the adjacent irradiation position. By doing so, the imaging position can be controlled at high speed within the depth of focus.

  The third mode of height adjustment by the imaging optical system drive unit of the present invention is to detect the height in the Z-axis direction of the next irradiation position one cycle ahead of the irradiation position in laser light irradiation. Using the detected height, the height of the imaging position in the Z-axis direction is adjusted at the next irradiation position of the laser beam.

  In this second aspect, in stepwise irradiation of laser light, by detecting the height at the next irradiation position, the irradiation position detected by the substrate height detection unit and the irradiation position where the laser light is irradiated Can be the same.

  According to the present invention, in the crystallization apparatus, the imaging position of the laser beam can be adjusted at high speed with respect to the waviness on the substrate side.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  A configuration example of the crystallization apparatus of the present invention will be described with reference to FIG.

  The crystallization apparatus 1 of the present invention includes an illumination optical system 2b that irradiates laser light, a light modulation element 2c that modulates the laser light irradiated by the illumination optical system 2b into a light beam having a predetermined light intensity distribution, and a light modulation element An imaging optical system 2d that forms an image of the modulated light 2c on the substrate (the substrate to be processed 20), and a substrate that supports the substrate (the substrate to be processed 20) and determines a two-dimensional position on the substrate (the substrate to be processed 20). Stage 3 is provided. The modulated light applied to the substrate (target substrate 20) through the imaging optical system 2d melts and crystallizes the thin film provided on the substrate.

  The illumination optical system 2b, the light modulation element 2c, and the imaging optical system 2d constitute the optical system 2. The illumination optical system 2b constitutes an excimer illumination optical system, and emits and adjusts crystallization leather light that illuminates the light modulation element 2c. The illumination optical system 2b can include a beam expander that expands the beam of excimer laser light emitted from the laser light source 2a and a homogenizer that equalizes the in-plane light intensity. In the figure, the beam expander and the homogenizer are not shown.

  The light modulation element 2c can use a phase shifter, and modulates the laser light for crystallization into light having a desired light intensity distribution, for example, a light intensity distribution having an inverse peak pattern.

  The imaging optical system 2d irradiates the non-single-crystal semiconductor thin film for crystallizing the crystallization laser light phase-modulated by the light modulation element 2c. Although FIG. 1 shows a projection system in which the light modulation element 2c is installed between the illumination optical system 2b and the imaging optical system 2d, the proximity in which the light modulation element 2c is installed close to the substrate 20 to be processed. It can also be a method.

  The laser light source 2a has a sufficient energy to melt a non-single crystal semiconductor film provided on the substrate 20 to be processed, such as an amorphous or polycrystalline semiconductor film, for example, 1 J / cm 2 on the non-single crystal semiconductor film. The light having The laser light source 2a is, for example, an excimer laser light source, and outputs a short pulse, for example, a pulsed laser beam having a half width of about 25 to 30 nsec. The laser beam is preferably, for example, a KrF excimer laser beam having a wavelength of 248 nm or a XeCl excimer laser beam having a wavelength of 308 nm.

  The excimer laser light source is, for example, a pulse oscillation type whose oscillation frequency is 10 Hz to 300 Hz, for example.

  The beam expander expands incident laser light, and can be composed of, for example, a concave lens that expands and a convex lens that converts light into parallel light. The homogenizer has a function of determining the dimension of the incident laser beam in the XY cross-sectional direction and uniforming the light intensity distribution in the determined shape. For example, a plurality of X direction cylindrical lenses are arranged in the Y direction to form a plurality of light beams arranged in the Y direction, and each light beam is superposed in the Y direction and redistributed by the X direction condenser lens. Similarly, a plurality of Y-direction cylindrical lenses are arranged in the X direction to form a plurality of light beams arranged in the X direction, and each light beam is superposed in the X direction and redistributed by the Y-direction condenser lens. The excimer laser light is dimmed by the homogenizer into illumination light having a predetermined angular spread and uniform light intensity in the cross section.

  The phase shifter is an example of the phase modulation element 11 and, for example, a step is provided on a quartz glass substrate. The laser beam is diffracted and interfered at the boundary between the steps to give a periodic spatial distribution to the laser beam intensity. For example, a phase difference of 180 ° between the left and right is added. A phase shifter having a phase difference of 180 ° on the left and right side modulates the incident light into a symmetric reverse peak light intensity distribution.

  The level difference (thickness distribution) d is obtained by d = λ / 2 (n−1) where λ is the wavelength of the laser beam and n is the refractive index of the transparent substrate of the phase shifter. From this relationship, the phase shifter can be manufactured, for example, by forming a step d corresponding to a predetermined phase difference on a quartz glass substrate. For example, assuming that the refractive index of the quartz substrate is 1.46, the wavelength of the KrF excimer laser light is 248 nm, so the step for adding a phase difference of 180 ° is 269.6 nm. The step of the quartz glass substrate can be formed by selective etching or FIB (Focused Ion Beam) processing. The phase shifter has a step formed so as to form a reverse peak light intensity distribution by phase-modulating the incident light, and shifts the phase of the excimer laser light by a half wavelength in the case of the above step amount. As a result, the laser light for irradiating the semiconductor film has a light intensity distribution having an arbitrary shape formed by combining phase shift portions (steps). According to this method, it is possible to realize a light intensity distribution having a higher degree of freedom than that of excimer laser light shielding by a metal pattern used in other methods.

  The laser light transmitted through the phase shifter is coupled with a predetermined light intensity distribution on the substrate 20 to be processed, which is placed at a position conjugate with the phase shifter (light modulation element 2c) by the excimer imaging optical system 2d corrected for aberration. Image. The excimer imaging optical system 2d is constituted by a lens group including, for example, a plurality of calcium fluoride (CaF2) lenses and a synthetic quartz lens. The excimer imaging optical system 12 has, for example, a reduction ratio of 1/5, N.P. A. : 0.13, resolving power: 2 μm, depth of focus: ± 10 μm, focal length: 30 mm to 70 mm unilateral or bilateral telecentric lens.

  Further, the substrate 20 to be processed that is subjected to the crystallization process is generally a non-single crystal semiconductor through an insulating film on a holding substrate such as an insulating substrate such as a glass substrate or a plastic substrate, or a semiconductor substrate (wafer) such as silicon. A film (eg, an amorphous silicon film, a polycrystalline silicon film, a sputtered silicon film, a silicon-germanium film, or a dehydrogenated amorphous silicon film) is formed on the non-single-crystal semiconductor film. An insulating film is provided as a cap film.

  The film thickness of the non-single-crystal semiconductor film is, for example, 30 nm to 300 nm, for example, 50 nm in the case of an amorphous silicon film subjected to dehydrogenation treatment. The insulating film is a film provided to prevent unwanted impurities from diffusing from the holding substrate into the non-single-crystal semiconductor film when the non-single-crystal semiconductor film is crystallized. Or it is the film | membrane provided in order to insulate the Joule heat by laser irradiation.

  The cap insulating film has a function of storing heat when the non-single-crystal semiconductor film receives light and melts for crystallization by using transmission characteristics and light absorption characteristics of the cap insulating film with respect to laser light. The heat storage effect of the cap insulating film enables crystallization with a large grain size (5 μm or more) in the molten region of the non-single crystal semiconductor film. The cap insulating film is for increasing the efficiency of crystallization, but can be saved.

  The substrate stage 3 includes an X-axis stage 3a movable in the X direction and a Y-axis stage 3b movable in the Y direction, and is driven and controlled by an XY stage controller (not shown). The substrate stage 3 is fixedly provided on the surface plate 5. An optical base portion (not shown) that supports the optical system 2 is fixed on the surface plate 5.

  The surface plate 5 is mounted on a floor surface (not shown) by a vibration isolation device 6. The vibration isolator 6 includes a spring element and a gain element, and is driven by a vibration isolator controller (not shown). The surface plate 5 and the substrate stage 3 and the optical base portion provided on the surface plate 5 are connected to the floor. Control so as not to vibrate relative to a reference surface such as a surface. Note that the XY stage controller and the vibration isolator control controller can be controlled by a host control PC (not shown).

  Furthermore, the crystallization apparatus 2 of the present invention includes an imaging optical system drive unit 8 that allows the imaging optical system 2d to move in the Z-axis direction. The imaging optical system drive unit 8 adjusts the height of the imaging optical system 2d in the Z-axis direction, thereby adjusting the height of the imaging position in the Z-axis direction. Here, the height of the imaging position in the Z-axis direction is matched with the surface height on the substrate 20 to be processed.

  The imaging optical system drive unit 8 is step-driven at the same periodic interval as the laser light emitted by the optical system 2, aligns the laser light at the irradiation position at a predetermined period, and emits the laser light from the optical system.

  The crystallization apparatus 1 of the present invention includes a substrate height detection unit 4 as means for detecting the height in the Z-axis direction of the position to be irradiated with laser light on the substrate 20 to be processed. The substrate height detector 4 includes, for example, a light source 4a that irradiates incident light incident on a measurement point, and a detector 4b that detects reflected light reflected at the measurement point.

  Based on the height signal in the Z-axis direction detected by the substrate height detector 4, the arithmetic circuit 7 is connected so that the imaging position of the modulated light of the imaging optical system 2 coincides with the substrate 20 to be processed. A control signal for controlling the image optical system driving unit 8 is generated. The imaging optical system drive unit 8 receives the control signal generated by the arithmetic circuit 7 and adjusts the height of the imaging optical system 2d in the Z-axis direction.

  Hereinafter, the aspect of height adjustment by the imaging optical system driving unit provided in the crystallization apparatus of the present invention will be described.

  Each aspect of the height adjustment by the imaging optical system drive unit of the present invention detects the height in the Z-axis direction of the irradiation position in laser light irradiation, and uses this detected height for laser light irradiation. At the position, the height of the imaging position in the Z-axis direction is adjusted.

  An operation example of each aspect of the crystallization apparatus of the present invention will be described with reference to the flowchart of FIG.

  The substrate stage 3 is moved to the reference position (S1), the height of the reference position is detected (S2), and set as the initial position (S3).

  Thereafter, the substrate stage 3 is driven to move to the starting position on the substrate 20 to be processed, and the imaging position is aligned with the crystallization processing position (S4), and then the substrate feed is started (S5). By repeating S9 to the final position, the semiconductor film provided on the substrate to be processed is crystallized (S10).

  The substrate stage 3 moves the substrate 20 to be processed by sequentially driving the X-axis stage 3a and the Y-axis stage 3b. The height of the irradiation position of the laser beam in the Z-axis direction is detected by the substrate height detection unit 4 (S6), and the arithmetic circuit 7 generates a drive signal based on the acquired height information and drives the imaging optical system. Send to section 8 (S7). The imaging optical system drive unit 8 receives this drive signal, controls the height of the imaging optical system 2d in the Z-axis direction (S8), and irradiates laser light (S9).

  Hereinafter, this first aspect will be described with reference to FIGS.

  3 and 4 are diagrams for explaining the relationship between the substrate and the imaging optical system driving unit in the first embodiment of the crystallization apparatus of the present invention, and FIG. 5 is a first diagram of the crystallization apparatus of the present invention. 6 is a timing chart for explaining the relationship between the substrate and the imaging optical system driving unit in the embodiment of FIG.

  The first aspect of the height adjustment by the imaging optical system drive unit of the present invention is to detect the height of the irradiation position in the Z-axis direction in the irradiation of the laser beam, and use the detected height for the laser. In light irradiation, the height of the imaging position in the Z-axis direction is adjusted.

  In each step in which the optical system 2 irradiates laser light onto the substrate 20 to be processed, the substrate height detection unit 4 detects the substrate height in the Z-axis direction of the irradiation position in that step. The imaging optical system drive unit 8 adjusts the imaging position using the substrate height in the Z-axis direction of the irradiation position detected in the irradiation step.

  FIG. 3 is a diagram for explaining an operation in continuous irradiation in the laser light irradiation cycle, and shows one irradiation during continuous laser light irradiation.

  FIG. 3 schematically shows a region where the target substrate 20 is crystallized by each laser light irradiation. Here, the target substrate 20 is irradiated with laser light while moving the target substrate 20 in the direction of the arrow. It is assumed that the region A, the region B, the region C,.

  FIG. 3 shows a state in which the region B is irradiated with laser light to be crystallized. In this crystallization, when the region B is crystallized by laser light irradiation, the height h1 of the substrate surface of the region A is detected and acquired, and the imaging optical system drive unit 8 is used by using the height h1. Driven to adjust the imaging position to height h1.

  In the height adjustment, there is a delay time corresponding to the response time from the start of driving of the imaging optical system drive unit 8 to the actual crystal position. In FIG. 3, the position where the height is detected is indicated by “x”, and the adjusted actual imaging position is indicated by “◯”. The height of the imaging position is not necessarily the same as the detection height h1, and there may be a height error Δh.

  Since the height error Δh is sufficiently small with respect to the waviness such as the waviness of the substrate and the variation in flatness of the substrate stage, the imaging position can be controlled within the depth of focus.

  A numerical example of the height deviation will be described by taking a case where laser light is irradiated at 100 Hz as an example. When the laser beam is irradiated at 100 Hz, the laser beam is irradiated stepwise at intervals of 10 msec. Therefore, it is necessary to correct the substrate height every 10 msec. A control amount is calculated based on the substrate height detected by the substrate height detection unit 4, and the imaging optical system is moved up and down by this control amount to perform a focusing operation. Assuming that the substrate stage 3 moves at a constant speed of 500 mm / sec, when the response time of the piezo stage, which is the imaging optical system drive unit, is 10 msec, this response time is 5 mm (= 500 mm / sec). The actual imaging position is delayed by (× 10 msec).

  Assuming, for example, a liquid crystal substrate of 730 mm × 920 mm and a substrate stage that supports the liquid crystal substrate as the substrate to be processed, the positional deviation of 5 mm due to the delay described above is slight, and the error in the height direction generated between these distances is Since it is within the depth direction margin (DOF) of the focal position, a height error at the actual imaging position can be tolerated.

  FIG. 4 shows the relationship between the height detection position and the imaging position for each irradiation. FIG. 4A shows an initial state, in which the imaging optical system driving unit 8 is driven based on the initial height h0, and the imaging position is aligned with the height h0.

  In FIG. 4B, the substrate height detection unit 4 detects the substrate height h1, and the imaging optical system drive unit 8 is driven based on this height information to align the imaging position with h1. To do. At this time, depending on the response time Δt of the imaging optical system driving unit 8, the position is between the detection position of the substrate height (“×” in the figure) and the imaging position (“◯” in the figure). Deviation occurs. This positional shift can be obtained from the response time Δt and the moving speed of the substrate stage.

  Similarly, in FIGS. 4C to 4E, in each laser light irradiation step, a positional deviation occurs between the substrate height detection position and the actual imaging position, and an error in the height direction occurs. It becomes a factor of.

  The substrate height detection unit detects the substrate height at the timing of FIG. 5A, and the imaging position optical system driving unit 8 performs alignment with the detected substrate height after the response time Δt (FIG. 5). (B)). After the alignment of the substrate height is completed, the laser beam is irradiated (FIG. 5C).

  The second aspect of the height adjustment by the imaging optical system drive unit of the present invention is to detect the height of the irradiation position in the Z-axis direction in the irradiation of the laser beam, and use the detected height to The height of the imaging position in the Z-axis direction is adjusted at the laser light irradiation position.

  In each step in which the optical system 2 irradiates laser light onto the substrate 20 to be processed, the substrate height detection unit 4 detects the substrate height in the Z-axis direction of the irradiation position in that step. The imaging optical system drive unit 8 determines the imaging position using the substrate height detected by the substrate height detection unit one cycle before, not the substrate height in the Z-axis direction of the irradiation position detected in the irradiation step. adjust.

  FIG. 6 is a diagram for explaining an operation in continuous irradiation in the laser light irradiation cycle, and FIGS. 6A and 6B show continuous laser light irradiation.

  FIG. 6 schematically shows a region in which the substrate 20 to be processed is crystallized by each laser light irradiation, as in FIG. 3. Here, the laser light is irradiated while moving the substrate 20 in the direction of the arrow. Thus, the region A, the region B, the region C,... Of the substrate 20 to be processed are crystallized in order.

  FIG. 6A shows a state where the region B is crystallized by being irradiated with laser light. In this crystallization, when the region A is crystallized at the time of the previous laser beam irradiation, the height h1 of the substrate surface of the region A is detected and acquired, and the imaging optical system is obtained using this height h1. The drive unit 8 is driven to adjust the imaging position to the height h1.

  FIG. 6B shows a state in which the region C is crystallized by being irradiated with laser light. In the crystallization in the region C, when the region B is crystallized at the time of the previous laser beam irradiation (FIG. 6A), the height h2 of the substrate surface of the region B detected and acquired is used. Then, the imaging optical system driving unit 8 is driven to adjust the imaging position to the height h2.

  In the above height adjustment, the height h2 of the region B is not necessarily the same as the height h1 of the region A, and there is a possibility that a height error Δh21 (= h2−h1) exists, and the same applies to the region C. In addition, the height h3 of the region C (the height of the region C is h3) is not necessarily the same as the height h2 of the region B, and there may be a height error Δh32 (= h3−h2).

  Since the height error Δh is sufficiently small with respect to the waviness such as the waviness of the substrate and the variation in flatness of the substrate stage, the imaging position can be controlled within the depth of focus.

  The numerical example of the second aspect corresponds to the numerical example shown in the first aspect when the length of each region in the moving direction is 5 mm.

  FIG. 7 shows the relationship between the height detection position and the imaging position for each irradiation. FIG. 7A shows an initial state, in which the imaging optical system driving unit 8 is driven based on the initial height h0, and the imaging position is aligned with the height h0. Here, the height h1 of the substrate is detected.

  In FIG. 7B, the imaging optical system driving unit 8 is driven based on the substrate height h1 detected in the previous period (FIG. 7A), and the imaging position is aligned with h1. At this time, depending on the response time Δt of the imaging optical system driving unit 8, the position is between the detection position of the substrate height (“×” in the figure) and the imaging position (“◯” in the figure). Deviation occurs. This positional shift can be obtained from the response time Δt and the moving speed of the substrate stage.

  Similarly, in FIGS. 7C to 7E, a position shift occurs between the substrate height detection position and the actual image formation position between the laser light irradiation steps, and the height direction is changed. It becomes a factor of error.

  The substrate height detection unit detects the substrate height at the timing of FIG. 7A, and the imaging position optical system driving unit 8 is aligned with the detected substrate height after the response time Δt (FIG. 7 ( b)). After the alignment of the substrate height is completed, the laser beam is irradiated (FIG. 7C).

  The substrate height detection unit detects the substrate height at the timing shown in FIG. 8A, and the imaging position optical system drive unit 8 then aligns with the substrate height in a cycle (FIG. 8B). After the alignment of the substrate height is completed, the laser beam is irradiated (FIG. 8C).

  In addition, as shown in FIGS. 8A to 8C, the arithmetic circuit adjusts the height of the irradiation step using the height obtained in the previous irradiation step as a control height, and the previous and previous times. The control height may be estimated by extrapolation using the height obtained in the irradiation step, and the height of the irradiation step may be adjusted using this extrapolated value.

  FIG.8 (d)-FIG.8 (e) have shown the case where control height is extrapolated using the height calculated | required by the last and last irradiation step.

  For example, the adjustment of the substrate height at time t3 is controlled by extrapolation using the height h2 detected at the previous irradiation step (time t2) and the height h1 detected at the previous irradiation step (time t1). (2h2-h1) is obtained.

  In the third aspect of height adjustment by the imaging optical system drive unit of the present invention, the height in the Z-axis direction of the next irradiation position one cycle ahead of the irradiation position is detected, and this detected height is used. Then, the height of the imaging position in the Z-axis direction is adjusted at the next irradiation position of the laser beam.

  In each step in which the optical system 2 irradiates the processing substrate 20 with laser light, the substrate height detection unit 4 detects the height in the Z-axis direction of the next irradiation position one cycle ahead of the irradiation position. The substrate height detection unit 4 is arranged at a position one cycle ahead in the direction opposite to the substrate from the position where the imaging optical system 2d forms an image, so that the next irradiation position one cycle ahead of the irradiation position. The height in the Z-axis direction can be detected.

  The imaging optical system drive unit 8 uses the substrate height at the next irradiation position one cycle ahead, instead of the substrate height in the Z-axis direction of the irradiation position detected in the irradiation step. Adjust the image position.

  FIG. 9 is a diagram for explaining an operation in continuous irradiation in the laser light irradiation cycle, and FIGS. 9A to 9C show continuous laser light irradiation.

  FIG. 9 schematically shows a region where the substrate 20 to be processed is crystallized by each laser beam irradiation, as in FIGS. 3 and 6. Here, the laser beam is moved while moving the substrate 20 to be processed in the direction of the arrow. , The region A, the region B, the region C,... Of the substrate 20 to be processed are sequentially crystallized.

  FIG. 9B shows a state in which the region B is crystallized by being irradiated with laser light. In this crystallization, the height H1 of the substrate surface in the region A is detected and acquired in advance (FIG. 9A), and the imaging optical system drive unit 8 is driven using this height H1, The imaging position is adjusted to the height h1.

  FIG. 9C shows a state where the region C is crystallized by being irradiated with laser light. In the crystallization in the region C, the height H2 of the substrate surface of the region C that has been detected and acquired when the region B was crystallized at the time of the previous laser light irradiation (FIG. 9B) is used. Then, the imaging optical system driving unit 8 is driven to adjust the imaging position to the height H2.

  In the height adjustment, the height H2 of the region B is obtained in the previous period, and therefore there is no height error.

  The substrate height detection unit performs height control based on the height detected in the previous cycle at each timing of FIGS. 10 (a) to 10 (e). Since the position where the height is detected coincides with the position where the height is controlled, a height shift caused by a delay due to the response time of the imaging optical system driving unit can be eliminated.

  The substrate height detection unit detects the substrate height at the timing shown in FIG. 11A, and the imaging position optical system driving unit 8 then aligns the same position with the substrate height in the next cycle (FIG. 11B). )). After the alignment of the substrate height is completed, the laser beam is irradiated (FIG. 11C).

  In the above description, the laser light irradiation is described as being performed in steps, but this laser light irradiation is not a step-and-repeat irradiation performed by intermittently moving the substrate, but a continuous feed that continuously moves the substrate. In step 1, the predetermined region is irradiated with laser light in steps.

  According to the present invention, it becomes possible to maintain the quality of pseudo crystal grains having a size of several μm formed by the PMELA crystallization technique in the entire region of the substrate, and by forming transistors on the crystal grains, there is little variation. The formation of high-performance circuits or crystal display devices can be expected.

  The vibration control of the present invention can be applied not only to a crystallization apparatus but also to an apparatus that is required to position a substrate at high speed and high accuracy. The present invention can also be applied to a semiconductor substrate measuring apparatus that measures the semiconductor substrate.

It is a figure for demonstrating one structural example of the crystallization apparatus of this invention. It is a flowchart for demonstrating the operation example of each aspect of the crystallization apparatus of this invention. It is the schematic for demonstrating operation | movement of the 1st aspect of this invention. It is a timing diagram for demonstrating operation | movement of the 1st aspect of this invention. It is a timing diagram for demonstrating operation | movement of the 1st aspect of this invention. It is the schematic for demonstrating operation | movement of the 2nd aspect of this invention. It is a timing diagram for demonstrating operation | movement of the 2nd aspect of this invention. It is a timing diagram for demonstrating operation | movement of the 2nd aspect of this invention. It is the schematic for demonstrating operation | movement of the 3rd aspect of this invention. It is a timing diagram for demonstrating operation | movement of the 3rd aspect of this invention. It is a timing diagram for demonstrating operation | movement of the 3rd aspect of this invention. It is a figure for demonstrating schematic structure of a crystallization apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Crystallizer, 2 ... Optical system, 2a ... Excimer laser, 2b ... Illumination optical system, 2c ... Light modulation element, 2d ... Imaging optical system, 3 ... Substrate stage, 3a ... X-axis stage, 3b ... Y-axis Stage 4, substrate height detection, 4 a, light source, 4 b, detector, 5, surface plate, 6, vibration isolator, 7, arithmetic circuit, 8, imaging optical system drive unit, 20, substrate to be processed.

Claims (4)

An illumination optical system that irradiates laser light; a light modulation element that modulates the laser light into a light beam having a predetermined light intensity distribution; and an imaging optical system that forms an image of the modulation light of the light modulation element on a substrate Optical system,
A substrate stage for supporting the substrate,
In a crystallization apparatus for melting and crystallizing a thin film provided on a substrate with modulated light,
A crystal optical system driving unit that adjusts the Z-axis direction position of the imaging optical system;
The crystallization apparatus characterized in that the crystal optical system drive unit adjusts the imaging position of the modulated light imaged by the imaging optical system by adjusting the position of the imaging optical system in the Z-axis direction. A substrate height detector for detecting the height of the substrate in the Z-axis direction;
2. The crystallization apparatus according to claim 1, wherein the crystal optical system driving unit adjusts a Z-axis direction position of the imaging optical system based on the substrate height detected by the substrate height detection unit. . The crystal optical system drive unit is step-driven at the same periodic interval as the laser light irradiation,
The substrate height detection unit detects the substrate height in the Z-axis direction of the irradiation position where the laser beam is irradiated on the substrate,
3. The crystallization apparatus according to claim 2, wherein the crystal optical system driving unit adjusts an imaging position using the substrate height detected by the substrate height detection unit one cycle ago. The crystal optical system drive unit is step-driven at the same periodic interval as the laser light irradiation,
The substrate height detection unit detects the substrate height in the Z-axis direction of the irradiation position one cycle ahead of the irradiation position where the laser beam is irradiated on the substrate,
3. The crystallization apparatus according to claim 2, wherein the crystal optical system driving unit adjusts an imaging position using the substrate height detected by the substrate height detection unit one cycle ago.

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