JP2009064944A - Laser annealing method, laser annealing device and manufacturing method for display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable laser annealing treatment not depending upon the height of an amorphous silicon film when the amorphous silicon film is crystallized by the laser annealing treatment. <P>SOLUTION: A reference value is set to the height of a substance to be irradiated, the height of the substance is measured, the film thickness of the substance is obtained by a comparison and an arithmetic operation with a reference data and a database for the current (a voltage) of a laser oscillation driving laser beams corresponding to the film thickness is prepared. An operation is returned to an origin starting annealing, line annealing is conducted in conjunction with the measurement of the height of the substance to be irradiated and an annealing state is evaluated by irradiation-unevenness image acquisition and image processing after an irradiation on completion of annealing. Comparison with the optimum conditions of the quantity of energy correction in laser beams and acquisition of correction value of annealing treatment in the next line are conducted successively on the basis of the evaluation. Hereinafter, comparison and arithmetic operations with the reference data are conducted repeatedly a fixed number of times. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laser annealing method for performing annealing treatment by irradiating a surface of a material with laser light, a laser annealing apparatus for performing the laser annealing method, and a method for manufacturing a display device using the laser annealing method. .

  Polycrystalline silicon (polysilicon) is often used for a channel layer of a thin film transistor widely used for a switching element such as a liquid crystal display. The film quality of the thin film determines the performance of the thin film transistor. In order to improve the film quality of the channel layer of this thin film transistor, for example, there is a method in which an amorphous material is crystallized or a thermal annealing treatment is performed in order to improve the grain size of the crystalline material. For example, as a method of forming a polysilicon film on an insulating substrate, laser annealing is performed by irradiating an amorphous silicon film formed on the surface of an insulating substrate made of glass, quartz, or the like with a laser annealing apparatus. There is a method of converting an amorphous silicon film into a polysilicon film by performing treatment (see, for example, Patent Document 1).

  In the annealing process, the film quality / film thickness of the amorphous silicon film, which is caused by the previous process, does not change from the viewpoint of ensuring the reliability of the film quality, improving the yield, etc. The beam shape and the irradiation energy of the laser beam are required not to change even when the laser beam is irradiated for a long time.

  However, changes in the film quality and film thickness of the amorphous silicon film due to the previous process have the following factors. For example, the stability of the amorphous silicon film deposition device and the pretreatment device cannot be ensured, and the stability of the laser state such as the energy profile of the laser beam irradiated to the irradiated material as an unstable element by the annealing device This is a factor such as inability to secure the sex.

  As for the annealing apparatus, for example, in the case of a pulse laser apparatus, the irradiation energy of the laser light is likely to be unstable with the deterioration of the excitation gas, and the light intensity of the laser light for each pulse varies. When amorphous silicon is laser-annealed with laser light with a variation in light intensity, the amorphous silicon film is subject to variations in the state of heating and melting, producing polycrystalline silicon having uniform crystal grains. It becomes difficult.

  In addition, as a method of determining the annealing conditions, for example, an operation method is adopted in which an optimum energy condition for irradiating a dummy irradiated material with laser light is determined in advance, and annealing is performed on a plurality of product substrates under the same conditions. There is a case. In this case, if there is a change in the energy profile of the laser beam in the laser annealing device, a difference from the standard optimum energy will occur, and the required specified value will not be reached, or the energy will be larger than the specified value. It will anneal, and there is a possibility that the crystallization will be in an excessive or insufficient state.

  The process of the previous process, which has a deep relationship with the annealing quality, depends on the stability of the amorphous silicon film deposition system or when the condition of the pretreatment system varies. Changes. As a result, with the optimal laser light energy obtained at the time of determining the laser annealing conditions, annealing is performed with an energy amount smaller than the required value of the required irradiation energy, or energy larger than the required value of the required irradiation energy. An amount of annealing is performed, and there is a possibility that the crystallization is in an excessive or insufficient state. As described above, in the amorphous silicon film having a variation in the state of heating and melting, the crystal grain size of the polycrystalline silicon film obtained by crystallization varies, which may cause variations in transistor characteristics.

JP 2005-79497 A

  The problem to be solved is that when an amorphous silicon film is crystallized by laser annealing, laser annealing that does not depend on the height of the amorphous silicon film is difficult.

  The present invention enables laser annealing treatment independent of the height of the amorphous silicon film when the amorphous silicon film is crystallized by laser annealing treatment.

  The laser annealing method of the present invention measures a reference value setting step for setting a reference value for measurement of an irradiated object, a height measuring step for measuring the height of the irradiated object, and the reference value. The height of the surface of the object to be irradiated is compared, the difference is calculated to obtain the film thickness, and a database of current values for driving the laser beam corresponding to the film thickness of the object to be irradiated is created. Returning to the reference position for starting the database and the annealing, measuring the height of the irradiated object on the annealing line, and simultaneously performing the annealing in a line with the laser output based on the current value, An image of the surface state immediately after the end of annealing is acquired, and an energy evaluation amount of the laser beam is calculated based on the image evaluation process for evaluating the annealing state from the image, and the evaluation of the annealing state. And a correction step of feedback to annealing in order, and performs repeatedly a predetermined number of times following the calculating step.

  In the laser annealing method of the present invention, the energy correction amount of the laser beam is calculated based on the laser beam oscillated with a current value for driving the laser beam corresponding to the film thickness of the irradiation object and the evaluation of the annealing state. The annealing process can be performed with the laser beam whose correction amount is fed back to the next annealing process. That is, laser light annealing with stable light intensity can be performed.

  The laser annealing apparatus of the present invention is a laser annealing apparatus that performs annealing treatment by irradiating the surface of an irradiation object with laser light continuously or pulsed, the laser irradiation unit for irradiating the irradiation object with laser light, and the irradiation object An annealing process using a stage that can move an object, a laser power source that drives the laser irradiation unit, a film thickness detection unit that measures the film thickness of the irradiated object, and laser light emitted from the laser irradiation unit An image detection unit that obtains an image of the processed region and evaluates the annealing state by image processing; and a current or voltage supplied from the laser power source based on detection results of the film thickness detection unit and the image detection unit And controlling the laser output of the laser irradiation unit and controlling the stage to control the irradiation position of the laser beam.

  With the laser annealing apparatus of the present invention, the laser annealing method of the present invention can be performed.

  The display device manufacturing method of the present invention is a display device manufacturing method including an annealing process in which an amorphous silicon film forming an active region of a thin film transistor is irradiated with laser light to be crystallized. A reference value setting step for setting a reference value for measurement of the object, a height measurement step for measuring the height of the object to be irradiated, and a height of the surface of the object to be obtained obtained by measurement with respect to the reference value And calculating the difference to obtain a film thickness, a database creating process for creating a current value database for driving a laser beam corresponding to the film thickness of the irradiated object, and a reference for starting annealing An annealing step of performing an annealing in a line shape with a laser output based on the current value at the same time as measuring the height of the irradiated object on the annealing line, and a surface state immediately after the annealing is finished An image evaluation step for obtaining an image of the image and evaluating the annealing state from the image, and a correction step for calculating the energy correction amount of the laser beam based on the evaluation of the annealing state and feeding back the correction amount to the next annealing process And performing by the laser annealing method that repeats the calculation step and subsequent steps a predetermined number of times.

  In the method for manufacturing a display device of the present invention, the laser annealing method of the present invention can be performed.

  Since the laser annealing method of the present invention can be annealed with a laser beam having a stable light intensity, for example, if an amorphous silicon film is annealed, a homogeneous polycrystalline silicon film having excellent crystallinity can be obtained. The transistor using the polycrystalline silicon film has an advantage that stable transistor characteristics can be secured. In addition, annealing failure can be prevented and yield can be improved.

  Since the laser annealing apparatus of the present invention can perform the laser annealing method of the present invention, annealing can be performed with laser light having a stable light intensity. For example, if an amorphous silicon film is annealed, the crystallinity can be improved. There is an advantage that an excellent homogeneous polycrystalline silicon film can be obtained.

  According to the method for manufacturing a display device of the present invention, the laser annealing method of the present invention can perform annealing for irradiating the amorphous silicon film forming the active region of the thin film transistor with laser light for crystallization. There is an advantage that a surface device in which a thin film transistor having the above characteristics is formed can be manufactured.

  FIG. 1 shows an embodiment (first example) related to the laser annealing method of the present invention, FIG. 1 shows a flowchart of one embodiment (first example) related to a laser annealing apparatus that performs this laser annealing method, and FIG. 2 is a schematic configuration perspective view and FIG. 3 is a schematic configuration diagram. The schematic configuration diagram of FIG. 3 shows details of a system configuration related to monitoring and feedback of the laser annealing apparatus focusing on one laser irradiation unit shown in FIG.

  First, as shown in FIG. 2, the laser annealing apparatus 1 of the present invention is a multi-head type laser annealing apparatus. A table Y-axis moving unit 21 is provided on the surface plate 11, and a table X-axis moving unit 22 is provided above the table Y-axis moving unit 21. On the table X-axis moving unit 22, a work chuck table 24 is installed via a table θ-axis moving unit 23. That is, the work chuck table 24 is movable in the θ direction by the table θ-axis moving unit 23, and the table θ-axis moving unit 23 is movable in the X-axis direction by the table X-axis moving unit 22. The table X-axis moving unit 22 is movable in the Y-axis direction by the table Y-axis moving unit 21. The table θ-axis moving unit 23 has a mechanism for correcting a minute amount in order to maintain parallelism with a circuit pattern (not shown) formed on the substrate 51.

  The table Y-axis moving unit 21, the table X-axis moving unit 22, and the table θ-axis moving unit 23 are numerical values so that the substrate 51 can move relative to a laser irradiation unit 35 described later. It is controlled. Further, the scales used in the table Y-axis moving unit 21 and the table X-axis moving unit 22 are completely calibrated in scale and right angle, and even if used as a reference, there is no problem. The table θ-axis moving unit 23 is rotatable in the XY axis plane, and the center position of the rotational movement is not changed even when the table θ-axis moving unit 23 rotates.

  In addition, the accuracy of the circuit pattern formed on the substrate 51, the accuracy when mounted on the work chuck table 24, the origin-finding accuracy of the table θ-axis moving unit 23, the alignment accuracy, the shape accuracy of the alignment mark, the alignment mark However, it is difficult to eliminate these factors. Therefore, the table θ-axis moving unit 23 having a mechanism for correcting the minute amount is an alignment camera (not shown) mounted on a support unit 31 described later, and sets the reference position of the circuit pattern. It recognizes and calculates to calculate a correction amount, and commands the correction amount to the table θ-axis moving unit 23 to enable a slight movement.

  Therefore, since the substrate 51 placed on the work chuck table 24 is movable in the X-axis direction, the Y-axis direction, and the θ direction, the substrate 51 can be guided to the laser irradiation position.

  The work chuck table 24 is for fixing the substrate 51. As the fixing method, various adsorption methods such as electrostatic adsorption and vacuum adsorption can be adopted. Alternatively, a mechanical fixing method using a clamp may be used.

  On the surface plate 11, a so-called portal-shaped support portion 31 is installed in a direction orthogonal to the table X-axis moving portion 21, and the beam portion 32 of the support portion 31 is parallel to the Y-axis direction. A guide rail 33 is provided, and a head moving unit 34 for moving the plurality of laser irradiation units 35 is provided along the guide rail 33. Accordingly, the laser irradiation unit 35 can be moved in parallel with the Y-axis direction by the head moving unit 34 and can be moved in the Z-axis direction. That is, the head moving unit 34 includes a Y-axis moving unit 34Y that moves in the Y-axis direction along the guide rail 33 and a Z-axis moving unit 34Z that moves in the Z-axis direction. The head moving unit 34 has a scale for grasping the position moved in the Y-axis direction along the guide rail 33 and a scale for grasping the position moved in the Z-axis direction.

  Since the head moving unit 34 includes the Z-axis moving unit 34Z, the distance between the laser irradiation unit 35 and the substrate 51 installed on the work chuck table 24 can be adjusted. Thereby, the laser beam emitted from the emission port of the laser irradiation unit 35 disposed to face the substrate 51 can be adjusted so as to be condensed on the surface of the substrate 51.

  In the laser annealing apparatus 1, the substrate 51 to be annealed is fixed on the work chuck table 24. As the table θ-axis moving unit 23 moves on the table X-axis moving unit 22, the substrate 51 performs a linear motion relative to each laser irradiation unit 35. At this time, if the laser beam is irradiated from the laser irradiation unit 35 at a designated timing, an annealing region is formed in a line shape on the substrate 51. If the table Y-axis moving unit 21 or the head moving unit 34 repeats the pitch movement in the Y-axis direction, the annealing process can be performed on the entire surface of the substrate 51.

  Next, details of the system configuration related to monitoring and feedback of the laser annealing apparatus focusing on the one laser irradiation unit 35 will be described with reference to the schematic configuration diagram of FIG.

  As shown in FIG. 3, in the laser annealing apparatus 1, the laser irradiation unit 35 is provided with a laser oscillator 61, and laser light oscillated by the laser oscillator 61 is amplified by the laser irradiation unit 35 and emitted. At that time, the intensity of the oscillated laser beam is detected by the monitor 62 provided in the laser irradiation unit 35. Then, the laser light intensity data acquired by the monitor 62 is sent to the laser power source 63 and fed back to the current value supplied from the laser power source 63, so that the laser oscillator 61 always supplies the laser oscillator 61 with the predetermined value. The current is controlled by the laser power supply 63 so that the oscillation intensity of the laser beam of the laser oscillator 61 becomes a predetermined intensity with respect to the current value of. That is, automatic current control is performed in the loop of the laser irradiation unit 35, the monitor 62, the laser power source 63, and the laser oscillator 61.

  Further, the laser light emitted from the laser irradiation unit 35 is shaped into a desired beam shape by passing through a homogenizer 37 that equalizes the light intensity. For example, it is shaped into a beam shape having an intensity distribution that is short in the X-axis direction, long in the Y-axis direction, and trapezoidal in each axial direction. A beam splitter 66 is installed in the optical path of the laser beam L between the laser irradiation unit 35 and the substrate 51, and a part of the laser beam L (for example, about 0.5% to 1%) is provided by the beam splitter 66. Is reflected in a direction perpendicular to the irradiation direction of the laser beam L, and the profile monitor 67 causes the substrate 51 (an object to be irradiated 52, for example, an amorphous silicon film, which is a thin film formed on the surface of the substrate 51). ) Is detected (particularly, the intensity distribution in the X-axis direction, which is the moving direction of the substrate 51). The process monitor 67 projects the separated laser beam L onto a photodetector (for example, CCD) (not shown) in the profile monitor 67 and measures the intensity distribution of the laser beam. In general, the position resolution of the CCD is high, and a resolution of, for example, about 1 μm can be obtained. Therefore, the amount of movement of the laser light can be measured by the CCD coordinate system.

  An energy power monitor 69 for observing the power distribution of the laser beam is installed in the vicinity of the work chuck table 24. The energy power monitor 69 measures the laser light intensity (energy) per unit area of the laser light L before irradiating the substrate 51 with the laser light L. Then, the information of the measured value in the energy power monitor 69 is fed back to the control unit 71, and the control unit 71 makes the reference laser beam intensity so that the light intensity of the laser beam L applied to the substrate 51 is constant. The current (or voltage) value supplied from the laser power source 63 to the laser oscillator 61 is changed based on the difference between the measured value of the laser beam intensity fed back and the laser beam intensity. That is, automatic power control is performed in the loop of the laser irradiation unit 35, the energy power monitor 69, the control unit 71, the laser power source 63, and the laser oscillator 61.

  The laser irradiation unit 35 is provided with a film thickness detector 72 for measuring the state of the irradiated object formed on the substrate 51 before irradiation with the laser light L. The film thickness detector 72 measures, for example, the film thickness of the irradiated object and the height (for example, surface roughness) of the irradiated object. Information on the measurement value obtained by the film thickness detector 72 is sent to the control unit 71, where the film thickness of the irradiated object on the substrate 51 to be detected and measured, the height of the irradiated object, The difference between the irradiation distance of the laser irradiation unit 35 and the optimum distance between the irradiation surfaces on the substrate 51 is calculated, and when the measurement position on the substrate 51 by the film thickness detector 72 comes to the irradiation position of the laser irradiation unit 35, The position of the laser irradiation unit 35 in the Z-axis direction is controlled. As a matter of course, since the position of the laser irradiation unit 35 before control in the Z-axis direction is transmitted to the control unit 71 in advance, the laser irradiation unit 35 is moved in the Z-axis direction by a necessary amount relative to the position before control. Will be moved.

  Since the film thickness detector 72 acquires the state of the irradiated object such as the film thickness of the irradiated object before irradiation with the laser beam and the height of the irradiated object, the film thickness and irradiation energy obtained in advance are obtained. Based on the relationship, from the film thickness information acquired by the film thickness detector 72 before the irradiation, for example, the table X-axis moving unit 22 is corrected so as to obtain the optimal irradiation energy, and the optimal apparatus state that does not depend on the film thickness. Can be held in.

  Further, the irradiation object / laser irradiation acquired by the film thickness detector 72 before irradiation based on the relationship between the irradiation energy and the distance between the laser beam emission ports of the irradiation object / laser irradiation unit 35 acquired in advance. For example, the Z-axis moving unit 34Z is corrected so that the optimum irradiation energy is obtained from the distance between the laser beam emission ports of the unit 35, and does not depend on the distance between the laser beam emission ports of the irradiated object / laser irradiation unit 35. It can be kept in an optimum apparatus state.

  Further, the laser irradiation unit 35 is provided with an image detector 73 for observing the state of the irradiated object formed on the substrate 51 after the laser light L irradiation. The image detector 73 includes, for example, an imaging unit 74 that captures the surface state of the substrate 51, an image processing unit 75 that processes an image captured by the imaging unit 74, and an illumination unit 76 that illuminates the imaging position from an oblique direction. The illumination unit 76 is dark field illumination. The image information obtained by the image detector 73 is sent to the control unit 71, and the control unit 71 optimizes the intensity of the laser light oscillated from the laser oscillator 61 based on the image information for annealing. A command is issued to the laser power source 63 and the output (for example, current) of the laser power source 63 is controlled.

  The control unit 71 collects various types of information from the film thickness detector 72, the image detector 73, and the energy power monitor 69, so that optimum annealing is performed based on information of each measurement value and image information. The current supplied from the laser power source 63 to the laser oscillator 61 is controlled.

  Further, position information from the table Y-axis moving unit 21, table X-axis moving unit 22, and table θ-axis moving unit 23 is sent to the stage movement control unit 77 and transmitted to the control unit 71. On the other hand, the control unit 71 instructs the stage movement control unit 77 on the irradiation position information of the laser beam L emitted from the laser irradiation unit 35, and the table movement axis 77 sends the table Y axis based on the command. The irradiation position of the substrate 51 is moved to the irradiation position of the laser irradiation section 35 by controlling the moving section 21, the table X axis moving section 22, the table θ axis moving section 23, and the head moving section 34 (Z axis moving section 34Z). At the same time, the substrate 51 is moved in a desired direction at an optimum speed. Thereby, it is possible to anneal the surface of the substrate 51 at a constant speed in a constant direction.

  In the laser annealing apparatus 1, the control unit 71 instructs the Z-axis moving unit 34 </ b> Z on which the laser irradiation unit 35 is mounted with correction values for the film thickness of the irradiation object and the height of the irradiation object. For the annealing state after irradiation and irradiation, a command is given to the laser power source 63 having a function of changing the current (or voltage) setting value during oscillation of the laser oscillator 61 in order to change the irradiation energy, or annealing is performed. Each stage is instructed to perform a correction by issuing a command to the stage movement control unit 77 that controls the speed of the stage during scanning.

  Further, the position of the laser beam L emitted from the laser irradiation unit 35 on the substrate 51 and the position observed by the film thickness detector 72 that acquires the state of the amorphous silicon film of the substrate 51 before the laser beam irradiation. The position observed by the image detector 73 that observes the modified state of the crystalline silicon film after irradiation is managed by the control unit 71. Each position is preferably the same position, but is not limited to the same position in order to avoid interference with the structure.

  In addition, the table X-axis moving unit 22, the table Y-axis moving unit 21, the table θ-axis moving unit 23, and the Z-axis moving unit 34Z detect the scale values of the respective axes by the stage movement control unit 77. Manage the position accurately. Then, the control unit 71 responsible for the calculation function sets the correction data to the specified value via the stage movement control unit 77 so that the table X axis movement unit 22, the table Y axis movement unit 12, the table θ axis movement unit 23, the Z axis The moving unit 34Z is operated. That is, each stage is numerically controlled by the stage movement control unit 77.

  By adopting the configuration of each moving unit, based on the relationship between the film thickness and the irradiation energy acquired in advance, the film thickness acquired by the film thickness detector 72 before irradiation is corrected so as to be the optimum irradiation energy, It is possible to maintain an optimum apparatus state independent of the film thickness. If a difference occurs based on the relationship between the energy of the laser beam obtained in advance and passing through the homogenizer 37 or the like for making the light intensity uniform and before irradiating the irradiated material, and the optimum irradiation energy, a laser oscillator The laser power source 63 that changes the current (or voltage) at the time of oscillation 61 can be corrected so as to obtain the optimum irradiation energy and can be held in the optimum apparatus state. Further, the crystallization state acquired by the image detector 73 after irradiation is shown based on the relationship between the irradiation energy and the value indicating the crystallization state acquired in advance (for example, by the method for evaluating crystallinity by transmitted light intensity). From the value (brightness map), correction can be performed so that the optimum irradiation energy is obtained, and the optimum apparatus state can be maintained.

  By having such a function, the thickness of the irradiated object detected by the film thickness detector 72 for observing the state of the irradiated object before irradiation, the value of the height of the irradiated object, and the like were measured. XY coordinate position data is stored, measured in advance, and a conversion formula is derived, so that the distance between the laser irradiation position and the thickness detection position of the film thickness detector 72 is taken into consideration, calculation, and correction information is transferred from the control unit 71 to the stage movement control. A command is issued to the unit 77, and at the time of laser irradiation, the Z-axis moving unit 34Z on which the laser irradiation unit 35 is mounted is operated to perform laser irradiation in a corrected state.

  The laser annealing apparatus 1 passes the current (or voltage) at the time of oscillation of the laser oscillator 61, the energy profile of the laser beam emitted from the laser oscillator 61, the homogenizer 37 that equalizes the light intensity, and the like to the irradiated object. Information indicating the state of the laser beam L, such as the energy profile of the laser beam L before irradiation, can be detected and monitored. For this reason, for example, a difference is generated based on the relationship between the optimum irradiation energy and the energy of the laser light L that has been acquired in advance and passes through the homogenizer 37 or the like that equalizes the light intensity and is irradiated on the object. For example, the current (or voltage) at the time of oscillation of the laser oscillator 61 can be changed by the laser power source 63. Therefore, it can correct | amend so that it may become optimal irradiation energy, and can hold | maintain in the optimal apparatus state.

  Moreover, since it has the image detector 73 which acquires the annealing state, for example, crystallization state, etc. of the irradiation object after irradiating the laser beam, for example, a value indicating the crystallization state acquired in advance (for example, Based on the relationship between the irradiation energy and the crystallinity based on the transmitted light intensity), the value indicating the crystallization state collected by the image detector 73 after the irradiation is corrected so that the optimum irradiation energy is obtained, and the optimum apparatus is obtained. Can be kept in a state. When correction is performed, optimization is performed including information such as the film thickness of the irradiated object before laser irradiation and the height of the irradiated object.

  Thereby, crystallization that does not depend on the difference in the film thickness of the irradiated substance and the height of the irradiated object can be realized.

  Next, a laser annealing method (first embodiment) using the laser annealing apparatus 1 will be described with reference to the flowchart of FIG. 1, the schematic configuration perspective view of FIG. 2, and the schematic configuration diagram of FIG. As an example, this laser annealing method is a method in which an amorphous silicon (amorphous silicon) film in a manufacturing process of a thin film transistor is heated and melted and crystallized to be modified into a crystalline silicon (polysilicon) film.

  Basically, the irradiated object formed on the substrate 51 placed on the work chuck table 24 is irradiated with the laser beam L emitted from the laser irradiation unit 35 and annealed. At this time, by moving the table X-axis moving unit 22 in the X-axis direction, a line that is heated by the laser beam and modified into the polycrystalline silicon film can be formed on the substrate 51. Then, the laser irradiation unit 35 (or the table X-axis moving unit 22) is sequentially pitch-shifted in the Y-axis direction, whereby the entire substrate 51 can be annealed to be modified into a polycrystalline silicon film.

  This laser annealing method is applied to both the multi-head type laser annealing apparatus 1 described above and the single-head type laser annealing apparatus. Hereinafter, the description will be given focusing on one laser irradiation unit 35 of the multi-head type laser annealing apparatus 1.

  As shown in FIG. 1, when measuring the shape (for example, film thickness, surface height, etc.) of the amorphous silicon film formed on the substrate 51, which is the object to be irradiated, by the “reference value setting step”, Set the measurement reference value (0 points). For example, when a glass substrate is used as the substrate 51, the surface thereof has a flatness of about several μm. Therefore, even if the amorphous silicon film is formed to have a uniform thickness, the height of the surface varies depending on the position of the substrate 51. Therefore, for example, an intermediate value between the maximum value and the minimum value of the expected height is set as the reference value (0 point). By setting the reference value (0 point) in this way, the measured value can be prevented from exceeding the measurement range.

  Next, the height of the amorphous silicon film that is an object to be irradiated is measured by the “height measurement step”. This measurement is performed by the film thickness detector 72. For example, the height of the amorphous silicon film is measured by scanning a line one line before the line to be annealed. Thus, the film thickness distribution is obtained. Of course, the annealing line may be measured. In this case, the number of measurement points is limited due to the relationship with the annealing rate, but a normal measurement of about five points can be sufficiently performed.

  For example, as shown in FIG. 4A, measurement is performed at five points (P0, P1, P2, P3, P4) at equal intervals in the X-axis direction of the substrate 51. For example, the measurement position line is one line before the annealing position line. In the vicinity of the center of the substrate 51 (circular region indicated by oblique lines), it is possible to crystallize amorphous silicon with normal annealing strength (laser light output), but in other regions, annealing strength (laser) If the light output) is not changed, annealing with low crystallinity occurs.

  Based on the measurement results, for example, a film thickness distribution as shown in FIG.

  Next, the “calculation step” compares the height of the surface of the substrate 51 with respect to the reference value with respect to the reference value, and compares the height of the film surface, which is the irradiated object, and calculates the difference.

  Next, a database of current values corresponding to the film thickness is created by the “database creation step”. Usually, as the film thickness increases, the amount of energy required for annealing increases. Therefore, the current value supplied from the laser power source 63 to the laser oscillator 61 needs to increase accordingly. Here, based on the measured value of the film thickness, the control unit 71 described above calculates a current correction value for correcting the current value supplied to the laser oscillator 61. As a result, for example, a correction current value for the measurement position as shown in FIG. Based on the corrected current value, the laser power supply 63 is instructed to supply a current value to be supplied to the laser oscillator 61.

  If the current value is known, the optimum energy value of the laser beam can be obtained from the heat capacity of the film. The basis for this will be described with reference to FIG.

  As shown in FIG. 5, there is a correlation between the drain-source current Ids of transistor characteristics, the unevenness of laser light irradiation, and the film thickness distribution (profiler) data. From this, by obtaining the film thickness distribution, the optimum energy of the laser beam can be determined, and the current value supplied to the laser oscillator 61 from the laser power source 63 for obtaining the energy can be obtained.

  Next, in the “annealing step”, the substrate 51 is returned to the reference position (origin) where the annealing of the substrate 51 is started, and annealing is performed in a line shape. In this case, line annealing is performed in the X-axis direction. At the same time, the film thickness detector 72 measures the height of the surface of the amorphous silicon film that is the object to be irradiated.

  In the annealing, it is preferable to obtain an optimum focal position by moving the Z-axis moving part 34Z in the Z-axis direction based on the measured value of the height of the amorphous silicon film.

  Next, in the “image evaluation step”, the annealed surface state at the laser light irradiation position immediately after the end of annealing is imaged by the imaging unit 74 to obtain an image, and the image processing unit 75 evaluates the annealed state from the image. In this evaluation, an optimal laser beam energy and an unevenness evaluation value (brightness map) of the annealed surface state are created in advance.

  It has been found that there is a strong correlation between the size of the crystal grain size generated by the annealing treatment, the size of the protrusions at the grain boundaries caused by the crystal grain size, and the unevenness of the annealed surface. This will be described with reference to FIGS.

  As shown in FIG. 6, for example, when the crystal grain size after crystallization is large, the protrusions at the grain boundaries become large as seen in the SEM photograph of the crystallization cross section of the silicon film, and therefore, the crystallized surface of the silicon film As seen in the SEM photograph, the unevenness of the annealed surface is greatly and uniformly distributed. In this case, the night vision image appears bright. As seen in the dark field image of the surface, the entire surface of the substrate 51 appears bright. That is, since the protrusions are large, the amount of light reflected from the protrusions increases, so it looks bright. In order to produce such a state, for example, the irradiation energy of the laser beam is set higher than the standard value, for example, +20 mJ. In this luminance map, deep grooves appear almost uniformly and flat.

  On the other hand, as shown in FIG. 7, for example, when the crystal grain size after crystallization is small, the protrusions at the grain boundaries are small as seen in the SEM photograph of the crystallization cross section of the silicon film. As seen from the SEM photograph of the surface, the unevenness of the annealed surface is small and unevenly distributed. In this case, the night vision image appears dark. As seen in the dark field image of the surface, the entire surface of the substrate 51 appears dark. That is, since the protrusion is small, the amount of light reflected from the protrusion is reduced, so that it looks dark. In order to produce such a state, for example, the irradiation energy of the laser beam is set lower than the standard value, for example, −20 mJ. In the luminance map in this case, the shallow grooves appear almost uniformly and flat.

  Here, an observation method of irradiation unevenness will be described with reference to FIG.

  As shown in the measurement method of FIG. 8, the illumination unit 76 illuminates the substrate 51 from an oblique direction, observes the protrusions on the surface of the crystallized silicon film (annealed surface) of the substrate 51, and captures the image of the image capturing unit. 74, and a brightness map is created by the image processing unit 75 (see FIG. 3). Thereby, the irradiation unevenness is quantified.

  For example, FIG. 8 (1) is a dark field image when the laser beam irradiation energy is larger than the standard value, for example, +20 mJ. FIG. 8 (2) is a dark field image when the laser beam irradiation energy is set to a standard value. FIG. 8 (3) is a dark field image when the irradiation energy of the laser beam is less than the standard value, for example, −20 mJ. Accordingly, the larger the protrusion on the annealed surface, the greater the amount of reflected light, so that the groove of the brightness map becomes deeper and looks brighter. Conversely, the smaller the protrusion on the annealed surface, the smaller the amount of reflected light, so that it can be seen that the grooves in the brightness map become shallower and appear darker.

  As shown in FIG. 5, the above-mentioned correction of the unevenness of irradiation is based on the fact that there is a correlation between the transistor characteristics, the unevenness of irradiation, and the irradiation conditions. Can be stabilized. For example, the irradiation unevenness of the laser beam is corrected by correcting the irradiation condition of the laser beam based on the detection result of the irradiation unevenness described above, and the state of the annealed region obtained by the laser beam irradiation is stabilized. It is preferable to correct the irradiation conditions including the above-described film thickness correction.

  Next, by evaluating the dark field image by the “correction step”, the annealing state is grasped, and the energy of the laser beam irradiated to the amorphous silicon film that is the object to be irradiated that has been created in the database in advance And an optimal laser beam energy correction amount is calculated based on the relationship between the dark field image and the unevenness evaluation (luminance map). Then, when the correction amount is fed back to the laser power source 63 and the annealing line is annealed next time, the annealing process is performed with the laser beam having the corrected energy value. Therefore, the above “calculation process” and subsequent steps are repeated.

  There are various determination methods for ending the annealing process. For example, the number of repetitions is set in advance, and is ended when the set number of repetitions is reached. Alternatively, the end point position may be set in advance, and the annealing process may be terminated when the end point position annealing is completed.

  Next, the laser annealing method (second embodiment) will be described below.

  Before irradiating the laser beam, the table X-axis moving unit 22 and the table Y-axis moving unit 21 are moved over the entire surface of the substrate 51 to detect values such as the film thickness of the irradiated object and the height of the irradiated object. The entire surface of, for example, an amorphous silicon film, which is an object to be irradiated on the substrate 51, may be corrected and irradiated with laser light.

  Further, by having the correction function, the annealing state (crystallization state, for example, crystallization rate (not limited to this) is detected by the image detector 73 that observes the annealing state after laser light irradiation. )) And XY coordinate position data at the time of measuring them, the distance information between the laser light irradiation position obtained in advance and the detection position of the image detector 73, and the film thickness detector 72 detect Considering information such as the film thickness of the irradiated material and the height of the irradiated object, the difference from the optimum irradiation energy is calculated from the information on the annealed state after irradiation, and the current (or voltage) during oscillation of the laser oscillator 61 is calculated. ) A command is given to the laser power source 63 having a function of changing to a set value, or a command is issued to the stage movement control unit 77 responsible for controlling the stage speed during annealing scanning. It may be subjected to laser beam irradiation while applying a.

  As a result, it is possible to realize laser light irradiation with an optimum irradiation energy and crystallization of an amorphous silicon film without depending on the difference in the film thickness of the irradiated material and the height of the irradiated object.

  In addition, it is possible to review the next annealing condition and adjust the already irradiated annealing line (for example, detect missing annealing and reanneal only the missing part).

  As described above, the laser oscillator 61 is irradiated with appropriate laser energy in consideration of the film thickness and height of the irradiated object (for example, an amorphous silicon film) before the laser beam irradiation for annealing treatment. By applying feedback, an optimal and uniformly crystallized polycrystalline silicon film can be formed in the surface of the substrate 51.

  In the above description, the amorphous silicon film is described as an example of the irradiation object. However, the present invention can be applied to the annealing process of other material films, and a uniform annealing process is realized in the surface of the substrate 51. be able to. Moreover, although the said board | substrate 51 was demonstrated as a glass substrate, the board | substrate 51 is not limited to a glass substrate, Various board | substrates, such as a semiconductor substrate, a plastic substrate, a ceramic substrate, can be used.

  Next, a display device to which the laser annealing method of the present invention is applied will be described below.

  As an example of a display device using the organic electroluminescent element 1, a configuration example of an organic EL display device will be described with reference to a panel configuration diagram of FIG.

  As shown in FIG. 9, a display region 111a and a peripheral region 111b are provided on a substrate 111 constituting the display device 110. In the display area 111a, a plurality of scanning lines 121 and a plurality of signal lines 123 are wired vertically and horizontally, and are configured as a pixel array section in which one pixel is provided corresponding to each intersection. Further, a scanning line driving circuit 125 that scans and drives the scanning line 123 and a signal line driving circuit 127 that supplies a video signal (that is, an input signal) corresponding to luminance information to the signal line 123 are arranged in the peripheral region 111b. Yes.

  The pixel circuit provided at each intersection of the scanning line 121 and the signal line 123 is composed of, for example, a switching transistor Tr1, a driving transistor Tr2, a storage capacitor Cs, and an organic electroluminescence element 111. When a scanning pulse is applied to the scanning line 121 by driving by the scanning line driving circuit 125 and a required signal is supplied to the signal line 123, the switching transistor Tr1 is turned on. As a result, the video signal written from the signal line 123 is held in the holding capacitor Cs, and a current corresponding to the held signal amount is supplied from the driving transistor Tr2 to the organic electroluminescent element 101. The organic electroluminescent element 101 emits light with luminance. The driving transistor Tr2 and the holding capacitor Cs are connected to a common power supply line (Vcc) 129.

  Note that the pixel circuit configuration described above is merely an example, and a capacitor circuit may be provided in the pixel circuit as necessary, or a plurality of transistors may be provided to configure the pixel circuit. Further, a necessary driving circuit may be added to the peripheral region 111b according to the change of the pixel circuit.

  Here, an example of a cross section of four pixels of the display device 100 will be described with reference to a schematic cross-sectional view of a main part in FIG.

  As shown in FIG. 10, a TFT substrate 113 in which a transistor Tr such as a driving transistor Tr2 and a switching transistor Tr1 (not shown) and a storage capacitor Cs (not shown) are arranged for each pixel is used as a driving substrate. The organic electroluminescent element 101 is provided through a planarization insulating film that also serves as a passivation film 131. Each organic electroluminescent element 101 includes a red-emitting organic electroluminescent element 101R that emits red, an organic electroluminescent element 101G that emits green, and an organic electroluminescent element 101B that emits blue in order in a matrix. Yes.

  When forming the active region 143 of each transistor Tr, the laser annealing method of the present invention is used. That is, after forming the gate electrode 141 and the gate insulating film 142 on the TFT substrate 113, an amorphous silicon film to be the active region 143 is formed. Next, the amorphous silicon film is modified into a crystallized silicon film by laser annealing. Thereafter, the crystallized silicon film is patterned to form an active region 143.

  Each organic electroluminescent element 101 includes a pixel electrode 151 connected to each transistor Tr through a connection hole formed in the planarization insulating film 131. Each pixel electrode 151 is insulated and separated by an insulating film pattern 153 covering the periphery. On these pixel electrodes 151, an organic layer 17 including a light emitting layer and a common electrode 157 common to each pixel are stacked, and the organic layer 155 is sandwiched between the pixel electrode 151 and the common electrode 157. Functions as the organic electroluminescent element 101.

  Among these, the pixel electrode 151 is configured as an anode and also has a function as a reflective layer, while the common electrode 157 is configured as a cathode and detects light generated in the organic layer 157 having a light emitting layer. On the other hand, it is configured as a semi-transmissive electrode having semi-transmissive properties. The organic layer 157 sandwiched between the pixel electrode 151 and the common electrode 157 resonates the emitted light generated in each organic layer and extracts it from the common electrode 157 side, depending on the emission color of each organic electroluminescent element 101. It shall be adjusted to a suitable film thickness. The organic layer 157 is laminated in order of, for example, a hole transport layer, a light emitting layer, and an electron transport layer from the pixel electrode 151 side serving as an anode, and the recombination of electrons and holes is effectively performed in the light emitting layer. It is the structure which light emission by.

  On the TFT substrate 113 on which the organic electroluminescent elements 101 as described above are arranged, a sealing substrate 161 is bonded with an adhesive 159 in a state of sandwiching the organic electroluminescent elements 101. The adhesive 159 and the sealing substrate 161 are made of a material that transmits light emitted from each organic electroluminescent element 101.

  Although not shown here, on the sealing substrate 161 made of a material such as transparent glass, for example, a red filter and a green color corresponding to each pixel portion (arrangement portion of the organic electroluminescence element EL). A filter and a color filter such as a blue filter may be provided. Further, a black matrix is provided between the pixels and at the periphery of the display area where the pixels are arranged, and the emitted light from each organic electroluminescent element 101 is taken out, and external light reflected by the organic electroluminescent element 101 or the like is taken out. Absorbs and improves contrast. These color filters and black matrix may be provided on either surface of the sealing substrate 161, but are desirably provided on the TFT substrate 113 side. This makes it possible to protect the color filter and the black matrix without exposing them to the surface.

  Further, as shown in FIG. 11, the display device 100 includes a module-shaped one having a sealed configuration. For example, a sealing portion 163 is provided so as to surround the display region 111a which is a pixel array portion having an organic electroluminescence element, and this sealing portion 163 is used as an adhesive to face a transparent portion such as glass (the sealing substrate 161). This corresponds to the display module formed by being pasted on. As described above, the transparent sealing substrate 161 may be provided with a color filter, a protective film, a black matrix, and the like. Note that the substrate 111 as a display module in which the display region 111a is formed may be provided with a flexible printed circuit board 165 for inputting / outputting a signal or the like to the display region 111a (pixel array unit) from the outside.

  Next, application examples of the display device according to the present invention described above to an electronic apparatus will be described with reference to FIGS.

  As the electronic device, a video signal input to an electronic device such as a digital camera, a notebook personal computer, a mobile terminal device such as a mobile phone, a video camera, or a video signal generated in the electronic device is displayed as an image or video. It can be applied to display devices for electronic devices in all fields. An example of an electronic device to which the present invention is applied will be described below.

  FIG. 12 is a perspective view showing a television to which the display device according to the present invention is applied. The television according to this application example includes a video display screen unit 301 including a front panel 302, a filter glass 303, and the like, and is created by using the display device according to the present invention as the video display screen unit 301.

  13A and 13B are diagrams showing a digital camera to which the display device according to the present invention is applied. FIG. 13A is a perspective view seen from the front side, and FIG. 13B is a perspective view seen from the back side. The digital still camera according to this application example includes a light emitting unit 311 for flash, a display unit 312, a menu switch 313, a shutter button 314, and the like, and is manufactured by using the display device according to the present invention as the display unit 312. The

  FIG. 14 is a perspective view showing a notebook personal computer to which the display device according to the present invention is applied. The notebook personal computer according to this application example includes a keyboard 322 that is operated when inputting characters and the like, a display unit 323 that displays an image, and the like as a display unit 323. It is produced by using.

  FIG. 15 is a perspective view showing a video camera to which the display device according to the present invention is applied. A video camera according to this application example includes a main body 331, a lens 332 for photographing an object on a side facing forward, a start / stop switch 333 at the time of photographing, a display unit 334, and the like. It is manufactured by using the display device according to the above.

  16A and 16B are diagrams showing a mobile terminal device to which the display device according to the present invention is applied, for example, a mobile phone, in which FIG. 16A is a front view in an open state, FIG. 16B is a side view thereof, and FIG. (D) is a left side view, (E) is a right side view, (F) is a top view, and (G) is a bottom view. A mobile phone according to this application example includes an upper housing 341, a lower housing 342, a connecting portion (here, a hinge portion) 343, a display 344, a sub-display 345, a picture light 346, a camera 347, and the like. It is manufactured by using the display device according to the present invention as the sub display 345.

It is the flowchart which showed one embodiment (1st Example) which concerns on the laser annealing method of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic structure perspective view which showed one Embodiment (Example) which concerns on the laser annealing apparatus which enforces the laser annealing method of this invention. It is the schematic block diagram which showed one embodiment (Example) which concerns on the laser annealing apparatus which enforces the laser annealing method of this invention. It is a relationship diagram of measuring the height of an object to be irradiated, the film thickness and current value, and the measurement position. It is the figure which showed the correlation between the drain-source current Ids of a transistor characteristic, the irradiation nonuniformity of a laser beam, and film thickness distribution (profiler) data. 6 is a drawing showing a protrusion state at a grain boundary, an uneven state on an annealed surface, and the like when a crystal grain size generated by annealing treatment is large. When the crystal grain size generated by the annealing process is small, it is a drawing showing the protrusion state at the grain boundary, the uneven state of the annealed surface, and the like. It is drawing explaining the observation method of irradiation nonuniformity. It is a panel block diagram which shows an example of the panel structure of the display apparatus with which the organic electroluminescent element of this invention is applied. It is a schematic structure sectional view showing an example of a panel composition of a display device to which an organic electroluminescent element of the present invention is applied. It is a block diagram which shows the module-shaped display apparatus of the sealed structure to which this invention is applied. It is a perspective view which shows the television to which this invention is applied. It is a figure which shows the digital camera to which this invention is applied, (A) is the perspective view seen from the front side, (B) is the perspective view seen from the back side. 1 is a perspective view showing a notebook personal computer to which the present invention is applied. It is a perspective view which shows the video camera to which this invention is applied. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the portable terminal device to which this invention is applied, for example, a mobile telephone, (A) is the front view in the open state, (B) is the side view, (C) is the front view in the closed state , (D) is a left side view, (E) is a right side view, (F) is a top view, and (G) is a bottom view.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Laser annealing apparatus, 61 ... Laser oscillator, 51 ... Substrate, 52 ... Irradiation object (amorphous silicon film), L ... Laser beam

Claims (5)

A reference value setting step for setting a reference value for measurement of the irradiated object;
A height measuring step for measuring the height of the irradiated object;
Comparing the height of the irradiated object surface obtained by measurement with respect to the reference value, calculating the difference to obtain the film thickness,
A database creating step for creating a database of current values for driving laser light corresponding to the film thickness of the irradiated object;
Returning to the reference position for starting the annealing, simultaneously measuring the height of the irradiated object in the annealing line, and simultaneously performing an annealing process in a line with a laser output based on the current value,
An image evaluation step of obtaining an image of the surface state immediately after completion of the annealing and evaluating the annealing state from the image;
An energy correction amount of the laser light is calculated based on the evaluation of the annealing state, and the correction amount is fed back to the next annealing process in order,
The laser annealing method, wherein the calculation step and the following steps are repeated a predetermined number of times. A position on the irradiated object irradiated with the laser beam;
A position on the irradiated object for obtaining an image of the annealed state after the laser light irradiation;
The position on the irradiated object for measuring the height of the irradiated object before being irradiated with the laser light is
The laser annealing method according to claim 1, wherein the laser annealing method is mutually recognized by a stage controller that controls a stage that moves the irradiation object. A laser annealing apparatus for performing annealing treatment by irradiating laser beam continuously or pulsed on the surface of an object,
A laser irradiation unit for irradiating an object with laser light;
A stage capable of moving the irradiated object;
A laser power source for driving the laser irradiation unit;
A film thickness detector for measuring the film thickness of the irradiated object;
An image detection unit that acquires an image of the region annealed by the laser light emitted from the laser irradiation unit and evaluates the annealing state by image processing;
Based on the detection results of the film thickness detection unit and the image detection unit, the current or voltage supplied from the laser power source is controlled to adjust the laser output of the laser irradiation unit, and the stage is controlled to control the laser. A laser annealing apparatus, comprising: a control unit that controls an irradiation position of light. A reference value setting step for setting a reference value for measurement of the irradiated object;
A height measuring step for measuring the height of the irradiated object;
Comparing the height of the irradiated object surface obtained by measurement with respect to the reference value, calculating the difference to obtain the film thickness,
A database creation step of creating a database of current values for driving laser light corresponding to the film thickness of the irradiated object;
Returning to the reference position for starting the annealing, simultaneously measuring the height of the irradiated object in the annealing line, and simultaneously performing an annealing process in a line with a laser output based on the current value,
An image evaluation step of obtaining an image of the surface state immediately after completion of the annealing and evaluating the annealing state from the image;
An energy correction amount of the laser light is calculated based on the evaluation of the annealing state, and the correction amount is fed back to the next annealing process in order,
The laser annealing apparatus according to claim 4, wherein the calculation process and subsequent steps are repeated a predetermined number of times. In a manufacturing method of a display device having an annealing process in which an amorphous silicon film forming an active region of a thin film transistor is crystallized by irradiating a laser beam,
The annealing step includes
A reference value setting step for setting a reference value for measurement of the irradiated object;
A height measuring step for measuring the height of the irradiated object;
Comparing the height of the irradiated object surface obtained by measurement with respect to the reference value, calculating the difference to obtain the film thickness,
A database creating step for creating a database of current values for driving laser light corresponding to the film thickness of the irradiated object;
Returning to the reference position for starting the annealing, simultaneously measuring the height of the irradiated object in the annealing line, and simultaneously performing an annealing process in a line with a laser output based on the current value,
An image evaluation step of obtaining an image of the surface state immediately after completion of the annealing and evaluating the annealing state from the image;
An energy correction amount of the laser light is calculated based on the evaluation of the annealing state, and the correction amount is fed back to the next annealing process in order,
A method for manufacturing a display device, comprising performing a laser annealing method in which the calculation step and subsequent steps are repeated a predetermined number of times.