Laser annealing system and laser annealing method

Abstract

A laser annealing system and a laser annealing method are provided. A laser annealing system for annealing a thin film by irradiating the thin film on a substrate with a pulsed laser light, the laser annealing system comprising: a laser device for outputting the pulsed laser light; an optical system that irradiates the thin film with pulse laser light; and a processor that performs control to irradiate the same portion of the thin film with the pulsed laser light by performing burst irradiation in which a burst period in which the pulsed laser light is continuously irradiated and a suppression period in which the irradiation of the pulsed laser light is suppressed are repeated.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a laser annealing system and a laser annealing method. BACKGROUND

[0002] Indium Tin Oxide (ITO) is used in flat panel displays, solar cells, and transparent electrode films using a glass substrate. The ITO is crystallized from an amorphous state by performing heat treatment (annealing), thereby improving its conductivity as an electrode and carrier mobility.

[0003] It is also desirable to apply transparent electrode films to optical integrated elements that realize higher-function devices. Optical integrated elements are realized by forming sensors, amplification circuits, CMOS (Complementary Metal Oxide Semiconductor) circuits, and the like active elements on the uppermost layer of an integrated circuit device. Therefore, a technology for manufacturing higher-quality transparent electrode films is required.

[0004] Furthermore, with diversification of information terminal devices, there is an increasing demand for flexible displays, flexible computers, and flexible solar cells that are small, light, consume less power, and can be freely bent. Therefore, a technology for forming high-quality transparent electrode films on plastic substrates such as PET (Polyethylene terephthalate) is required.

[0005] In order to form high-quality transparent electrode films on glass substrates, integrated circuits, or plastic substrates, crystallization of transparent electrode films needs to be performed without causing thermal damage to these substrates. Glass substrates used in displays require a process temperature of 400°C, in contrast to PET for integrated circuits and plastic substrates, which requires a process temperature of 150°C or lower.

[0006] In addition, in alloying of metal films used in magnetic sensor elements and the like, a metal material film is formed on a magnetic shielding substrate and annealed. There are also materials that lack heat resistance in the magnetic shielding substrate, and therefore, only the surface layer of the upper layer to be alloyed needs to be heated.

[0007] In addition to transparent electrodes and magnetic sensor elements, annealing is used in low-resistance of electrode wiring of LSI (Large Scale Integrated circuit), crystallization recovery in the process of semiconductors, and diffusion of dopants, and depending on the material and structure of the lower layer, there are processes in which thermal influence is to be avoided.

[0008] As a technique of annealing only a surface layer without causing thermal damage to a base substrate, a laser annealing method is used. In this method, in order to suppress damage to the substrate by heat diffusion, a pulsed ultraviolet laser that is absorbed by the upper semiconductor thin film is used.

[0009] In the case where the semiconductor thin film is silicon, a XeF excimer laser with a wavelength of 351 nm, a XeCl excimer laser with a wavelength of 308 nm, a KrF excimer laser with a wavelength of 248 nm, or the like is used. These ultraviolet region gas lasers have the following characteristics compared to solid lasers: low interference of laser light, excellent energy uniformity of a laser light irradiation surface, and the ability to uniformly anneal a wide region with high pulse energy.

[0010] Patent Literature 1: Japanese Patent Application Publication No. 2020-202242

[0011] Patent Literature 2: U.S. Patent Application Publication No. 2022 / 0072663 SUMMARY

[0012] A laser annealing system of one aspect of the present disclosure anneals a thin film on a substrate by irradiating the thin film with pulsed laser light, wherein the laser annealing system has: a laser device that outputs pulsed laser light; an optical system that irradiates the thin film with the pulsed laser light; and a processor that controls, by performing burst irradiation in which a burst period in which the pulsed laser light is continuously irradiated and a suppression period in which irradiation of the pulsed laser light is suppressed are repeated, the thin film at the same position.

[0013] A laser annealing method of another aspect of the present disclosure anneals a thin film on a substrate by irradiating the thin film with pulsed laser light, wherein the laser annealing method includes the steps of: a laser device outputting pulsed laser light from the laser device; irradiating the thin film with the pulsed laser light by an optical system; and irradiating the thin film at the same position by performing burst irradiation in which a burst period in which the pulsed laser light is continuously irradiated and a suppression period in which irradiation of the pulsed laser light is suppressed are repeated. BRIEF DESCRIPTION OF DRAWINGS

[0014] Hereinafter, several embodiments of the present disclosure will be described only as examples with reference to the accompanying drawings.

[0015] Figure 1 is a graph showing an example of burst operation of a laser device.

[0016] Figure 2 The structure of an exemplary laser annealing system is schematically shown.

[0017] Figure 3The graph shows the pulse energy of the pulsed laser irradiating the ITO film during the laser annealing process of Comparative Example 1, and the temperature near the surface of the ITO film irradiated by the laser (film surface temperature) as a result.

[0018] Figure 4 This is a graph showing an example of the pulse energy of the pulsed laser irradiating the ITO thin film during the laser annealing process of Comparative Example 2, the change in the surface temperature of the film irradiated by the laser, and the change in the temperature near the interface between the ITO film and the substrate (interface temperature).

[0019] Figure 5 This is a graph showing an example of sudden irradiation performed by the laser annealing system of Embodiment 1, and an example of the shift in film surface temperature and interface temperature under sudden irradiation.

[0020] Figure 6 This is a graph showing an example of sudden irradiation performed by the laser annealing system of Modification 1 of Embodiment 1, and an example of the change in surface temperature and interface temperature of the thin film accompanying the sudden irradiation.

[0021] Figure 7 The structure of the laser annealing system of Modification 2 of Embodiment 1 is shown in a schematic diagram.

[0022] Figure 8 It is Figure 7 The side view of the cooling plate and the irradiated object is shown in magnification.

[0023] Figure 9 This is a timing diagram illustrating a control example of the cooling operation.

[0024] Figure 10 It is a graph showing the temperature change of the thin film surface under continuous pulsed laser irradiation.

[0025] Figure 11 It is schematically shown in Figure 10 The diagram illustrates the crystallization process of a thin film under continuous pulsed laser irradiation.

[0026] Figure 12 The graph shows examples of burst modes and the temperature shift of the thin film surface accompanying burst irradiation.

[0027] Figure 13 It is shown schematically in Figure 12 The diagram illustrates the crystallization process of a thin film under sudden irradiation.

[0028] Figure 14 Schematic illustration of passing through Figure 12 The grains shown are generated by sudden irradiation.

[0029] Figure 15 This is a graph showing an example of sudden irradiation of the laser annealing system of Embodiment 2, and an example of the temperature change of the thin film surface accompanying the sudden irradiation.

[0030] Figure 16 It is shown schematically in Figure 15 The diagram illustrates the crystallization process of a thin film under sudden irradiation.

[0031] Figure 17 Examples of sudden irradiation of a variation of Embodiment 2, Example 1, and examples of the temperature shift of the thin film surface accompanying sudden irradiation are shown.

[0032] Figure 18 Examples of sudden irradiation in a variation of Embodiment 2 are shown, as well as examples of the temperature shift of the thin film surface accompanying sudden irradiation.

[0033] Figure 19 The structure of the laser annealing system of Embodiment 3 is shown in a schematic diagram.

[0034] Figure 20 This is a perspective view showing an example of a roller-to-roll conveyor mechanism used in a laser annealing system.

[0035] Figure 21 This is an explanatory diagram showing the structure and operation of the laser annealing system of Modified Example 1 of Embodiment 3.

[0036] Figure 22 The structure of the laser annealing system of Modification 2 of Embodiment 3 is shown in a schematic diagram.

[0037] Figure 23 The structure of the laser annealing system of Embodiment 4 is shown in a schematic diagram.

[0038] Figure 24 This is a graph illustrating an example of burst irradiation achieved through a laser annealing system. Detailed Implementation

[0039] -Table of Contents- 1. Explanation of Terms

[0040] 2. Examples of laser annealing systems

[0041] 2.1 Structure

[0042] 2.2 Actions

[0043] 3. Topic 1

[0044] 4. Implementation Method 1

[0045] 4.1 Structure

[0046] 4.2 Actions

[0047] 4.3 Functions / Effects

[0048] 4.4 Variation of Implementation Method 1 14.4.1 Structure

[0049] 4.4.2 Actions

[0050] 4.4.3 Function / Effect 4.5 Variation of Implementation Method 1 4.5.1 Structure

[0051] 4.5.2 Actions

[0052] 4.5.3 Functions / Effects 5. Topic 2

[0053] 6. Implementation Method 2

[0054] 6.1 Structure

[0055] 6.2 Actions

[0056] 6.3 Functions / Effects

[0057] 6.4 Variation 1 of Embodiment 2 6.5 Variation 2 of Embodiment 2 6.6 Others

[0058] 7. Implementation Method 3

[0059] 7.1 Structure

[0060] 7.2 Actions

[0061] 7.3 Examples of Conveying Mechanisms

[0062] 7.4 Functions / Effects

[0063] 7.5 Variation 1 of Implementation Method 3

[0064] 7.5.1 Structure

[0065] 7.5.2 Actions

[0066] 7.5.3 Function / Effect

[0067] 7.6 Variation 2 of Implementation Method 3

[0068] 7.6.1 Structure

[0069] 7.6.2 Actions

[0070] 7.6.3 Functions / Effects

[0071] 8. Implementation Method 4

[0072] 8.1 Structure

[0073] 8.2 Actions

[0074] 8.3 Functions / Effects

[0075] 9. Other uses besides ITO film

[0076] 10. About the processor

[0077] 11. Other

[0078] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. The embodiments described below illustrate several examples of this disclosure and do not limit its scope. Furthermore, the structures and operations described in each embodiment are not necessarily all necessary for the structures and operations of this disclosure. Additionally, the same reference numerals are used to denote the same structural elements, and repeated descriptions are omitted.

[0079] 1. Explanation of terminology

[0080] Figure 1 This is a graph illustrating an example of a burst operation of a laser device. Laser devices sometimes output pulsed laser light through burst operations. A burst operation is an action that repeats a burst period during which pulsed laser light is continuously output at a constant repetition frequency for a certain period, and a rest period during which no pulsed laser light is output. During the burst period, pulsed laser light is output from the laser device. During the rest period, the output of pulsed laser light ceases.

[0081] The repetition pattern during bursts and rest periods, i.e., the burst pattern, is defined by data including pulse energy, repetition frequency, and number of pulses during the burst period, as well as any or multiple of the following: length of the rest period and number of bursts. The burst pattern is indicated by external devices such as the exposure machine or processing machine.

[0082] A sudden signal is a signal that is activated during a sudden event and deactivated during a pause; it is a signal that specifies a sudden action.

[0083] 2. Examples of laser annealing systems

[0084] 2.1 Structure

[0085] Figure 2 The structure of an exemplary laser annealing system 10 is shown in schematic form. The laser annealing system 10 includes a laser device 12, an optical path tube 13, and a laser annealing apparatus 14.

[0086] Laser device 12 is a laser device that outputs pulsed ultraviolet light. For example, laser device 12 may also be a discharge-excited laser device that uses F2, ArF, KrF, XeCl, or XeF as the laser medium. Alternatively, laser device 12 may also be a solid-state laser device that outputs ultraviolet wavelengths.

[0087] The laser device 12 includes an oscillator 20, a monitor module 24, an optical shutter 26, and a laser control processor 28.

[0088] The oscillator 20 includes a cavity 30, an optical resonator 32, a charger 36, and a pulsed power module (PPM) 38.

[0089] An excimer laser gas is sealed in cavity 30. Cavity 30 includes a pair of electrodes 43 and 44, an insulating component 45, and windows 47 and 48.

[0090] The optical resonator 32 consists of a rear mirror 33 and an output coupler (OC) 34. A high-reflectivity film and a partial-reflectivity film are coated on the planar substrate in both the rear mirror 33 and the OC 34. A cavity 30 is positioned in the optical path of the optical resonator 32.

[0091] PPM38 includes a switch 39 and a charging capacitor (not shown). Switch 39 is connected to a signal line that transmits control signals from laser control processor 28.

[0092] Charger 36 is connected to the charging capacitor of PPM38. Charger 36 receives charging voltage data from laser control processor 28 and charges the charging capacitor of PPM38.

[0093] The monitor module 24 includes a beam splitter 50 and a light sensor 52.

[0094] The shutter 26 is configured in the optical path of the pulsed laser output from the monitor module 24. The optical path of the pulsed laser can also be sealed by a housing and optical path tube 13 (not shown) and purged with an inert gas such as N2.

[0095] The optical path tube 13 is a cover for the optical path of the pulsed laser between the exit port of the pulsed laser of the laser device 12 and the entrance port of the laser annealing device 14.

[0096] The laser annealing apparatus 14 includes an irradiation optical system 70, a frame 72, an XYZ stage 74, a stage 76, and a laser annealing control processor 100.

[0097] The illumination optical system 70 includes high-reflectivity mirrors 111, 112, and 113, an attenuator 120, an illumination optical system 130, a mask 140, a projection optical system 142, a window 146, and a housing 150. The illumination optical system 70 is an example of an "optical system" in this disclosure.

[0098] The high reflectivity mirror 111 is configured such that the pulsed laser light after passing through the optical path tube 13 passes through the attenuator 120 and is incident on the high reflectivity mirror 112.

[0099] Attenuator 120 is disposed in the optical path between high reflectivity mirror 111 and high reflectivity mirror 112. Attenuator 120 includes two partial reflectors 121 and 122 and rotating stages 123 and 124 that allow the incident angles to be varied toward each reflector.

[0100] The high-reflectivity mirror 112 is configured to allow the pulsed laser light after passing through the attenuator 120 to be incident on the high-reflectivity mirror 113. The high-reflectivity mirror 113 is configured to allow the pulsed laser light incident on the high-reflectivity mirror 113 to be incident on the fly-eye lens 134 of the illumination optics system 130.

[0101] The illumination optics system 130 includes a fly-eye lens 134 and a condenser lens 136. The illumination optics system 130 is configured to perform Kohler illumination on a mask 140 using a rectangular beam. A rectangular beam refers to a beam with a rectangular shape in which the light intensity distribution is homogenized.

[0102] The fly-eye lens 134 is configured, for example, such that the focal plane of the fly-eye lens 134 coincides with the front focal plane of the condenser lens 136. The condenser lens 136 is configured such that the rear focal plane of the condenser lens 136 coincides with the position of the mask 140.

[0103] Mask 140 is, for example, a photomask on a synthetic quartz substrate through which ultraviolet light is transmitted, having a pattern of a multilayer film of metal or dielectric formed. Mask 140, for example, has a pattern of lines and spacing.

[0104] The projection optical system 142 is configured to image the mask 140 onto the surface of the object 160 via the window 146. The projection optical system 142 may be a combination of multiple lenses 143, 144, or it may be a reduction projection optical system.

[0105] Window 146 is positioned in the optical path of the pulsed laser between the projection optics system 142 and the irradiated object 160. Window 146 is disposed in a hole provided in the housing 150, separated by an O-ring (not shown). Window 146 is a CaF2 crystal or synthetic quartz substrate through which the excimer laser passes, and reflection suppression films can be coated on both sides.

[0106] The housing 150 is provided with an inlet 152 and an outlet 154 for N2 gas. An N2 gas supply source is connected to the inlet 152 via a piping not shown. The housing 150 may also be sealed with an O-ring or the like to prevent external gases from mixing into the housing 150.

[0107] The illumination optical system 70 and the XYZ stage 74 are fixed to the frame 72. A stage 76 is fixed on the XYZ stage 74. The object to be irradiated 160 is fixed on the stage 76. The stage 76 is an example of a mounting platform for the object to be irradiated 160.

[0108] The object to be irradiated 160 may be, for example, a PET substrate on which an a-ITO film is coated.

[0109] 2.2 Actions

[0110] The laser annealing control processor 100 reads in the irradiation condition parameters during laser annealing. Specifically, the laser annealing control processor 100 reads in the target flux Fa, target pulse energy Et, number of irradiation pulses Na, and repetition frequency fa during laser annealing.

[0111] The laser annealing control processor 100 sends the target pulse energy Et to the laser control processor 28 and sends the emission trigger Tr1 corresponding to the irradiation pulse number Na and repetition frequency fa to the laser control processor 28.

[0112] The laser control processor 28 receives the target pulse energy Et from the laser annealing control processor 100.

[0113] The laser control processor 28 receives the emission trigger Tr1 at a repetition frequency fa to control the oscillator 20 to oscillate at the repetition frequency fa.

[0114] The pulsed laser output from oscillator 20 is sampled by beam splitter 50 of monitor module 24, and the pulse energy E is measured by optical sensor 52. Laser control processor 28 controls the charging voltage of charger 36 in a manner that makes the difference ΔE between pulse energy E and target pulse energy Et close to 0.

[0115] The pulsed laser beam after passing through the beam splitter 50 of the monitor module 24 is incident on the laser annealing device 14 via the optical path tube 13.

[0116] The pulsed laser incident on the laser annealing apparatus 14 is reflected by the high-reflectivity mirror 111, and is reduced by the attenuator 120 before being reflected by the high-reflectivity mirror 112. At this time, the laser annealing control processor 100 controls the incident angles of the two partial reflectors 121 and 122 through the rotary stages 123 and 124 in a manner that makes the flux at the position of the surface of the irradiated object 160 (the image of the mask 140) the target flux Fa.

[0117] The pulsed laser, after being highly reflected by the high-reflection mirrors 112 and 113, is illuminated on the mask 140 by the illumination optics system 130, which spatially homogenizes its light intensity.

[0118] The pulsed laser, after passing through the mask 140, is projected onto the surface of the irradiated object 160 by the projection optics system 142.

[0119] The laser annealing control processor 100 controls the XYZ stage 74 in such a way that the image of the mask 140 transferred by the projection optics system 142 is projected to the appropriate position.

[0120] A pulsed laser is irradiated onto the object 160 in the area to be transferred and imaged via a projection optics system 142. As a result, the portion of the surface of the object 160 irradiated by the pulsed laser is annealed.

[0121] Excimer lasers can efficiently heat relatively shallow surfaces of the irradiated material. Therefore, by using laser annealing with laser device 12, the impact on the substrate can be suppressed, and thin films such as ITO formed on substrates with low heat resistance temperatures can be polycrystalline.

[0122] 3. Topic 1

[0123] The following explanation uses ITO thin films as an example. In the field of laser annealing, there is a need to shorten processing time and increase the processing volume (production output) per unit time. To meet this requirement, increasing the laser injection level is considered. However, when increasing the laser injection level, the ITO thin film itself sometimes undergoes laser ablation. Due to the damage caused by ablation, the ITO thin film sometimes cannot guarantee both conductivity and transparency. Therefore, the laser injection level is limited to a value that prevents laser ablation of the ITO thin film.

[0124] Figure 3 This is a graph showing the pulse energy of the pulsed laser irradiating the ITO thin film and the temperature change near the surface of the ITO thin film during the laser annealing process of Comparative Example 1. The comparative examples are methods known only to the applicant and are not publicly known examples acknowledged by the applicant.

[0125] exist Figure 3 The image shows an example of a situation where multiple pulsed lasers are intermittently irradiated at specified time intervals. Figure 3 The diagram shows three pulses. Figure 3 The vertical axis represents pulse energy or temperature, and the horizontal axis represents time. The temperature near the surface of the ITO thin film, Hs (hereinafter referred to as the film surface temperature Hs), is shown by a solid line, and the pulse energy of the pulsed laser is schematically shown by a shaded block.

[0126] When crystallizing amorphous ITO thin films using laser annealing, the surface temperature Hs of the ITO film needs to be raised above the crystallization threshold temperature Hcz. For this to be achieved, the pulse energy of the pulsed laser needs to reach a certain level. The crystallization threshold temperature Hcz is the temperature at which crystallization occurs and is synonymous with the crystallization temperature.

[0127] On the other hand, when irradiated with a high-flux pulsed laser exceeding the ablation threshold of the ITO film, the ITO film itself will undergo ablation. Therefore, the pulsed laser flux is limited to a value lower than the ablation threshold. The ablation threshold is the lower limit of the laser flux required to produce laser ablation.

[0128] like Figure 3 Therefore, the pulse energy of the pulsed laser irradiating the ITO thin film is set to a value that will not cause laser ablation, specifically the threshold energy Eab. The threshold energy Eab is equivalent to converting the ablation threshold into an energy value.

[0129] That is, in Figure 3 In the laser annealing process of Comparative Example 1 shown, the pulse energy of the pulsed laser is appropriately adjusted so that the surface temperature Hs of the thin film rises to a temperature above the crystallization threshold temperature Hcz within the duration of each pulse, and laser irradiation is performed under conditions that do not produce laser ablation.

[0130] On the other hand, as another way to increase production, high repeatability of laser irradiation is considered. Figure 4 This example is shown. Figure 4 This is a graph showing an example of the pulse energy of the pulsed laser irradiating the ITO thin film, the change in the thin film surface temperature Hs accompanying laser irradiation, and the change in the temperature Hi (hereinafter referred to as interface temperature Hi) of the interface between the ITO thin film and the substrate during the laser annealing process of Comparative Example 2. The interface temperature Hi can be understood as the substrate temperature near the interface between the ITO thin film and the substrate.

[0131] exist Figure 4 The image shows an example of irradiating a pulsed laser at a specified repetition frequency within a specified period. Figure 4 The vertical axis represents pulse energy or temperature, and the horizontal axis represents time. For example... Figure 4 Therefore, when the pulsed laser irradiating the ITO thin film is highly repetitive, heat accumulates in the ITO thin film, and the surface temperature Hs of the film can be maintained above the crystallization threshold temperature Hcz for a long time. When this state continues, crystal nuclei are continuously generated, and the final grains become smaller.

[0132] Furthermore, the highly repetitive heat storage effect not only causes heat to penetrate near the surface of the ITO film but also to the interface between the ITO film and the substrate. Under continuous heat storage, the interface temperature Hi can sometimes exceed the substrate's damage threshold temperature Hbd, becoming a cause of substrate damage. The damage threshold temperature Hbd is the temperature at which the substrate will suffer irreversible damage such as surface cracking and film peeling when it exceeds this temperature, and it varies depending on the material.

[0133] Therefore, in addition to the flux, the repetition frequency of the pulsed laser is also limited, and the number of irradiations required to achieve crystallization becomes very large.

[0134] As mentioned above, production volume is limited when polycrystalline films such as ITO and IGZO are produced by laser annealing. This effect is particularly pronounced when the substrate is made of materials with low heat resistance, such as PET resin and polycarbonate (PC).

[0135] Therefore, there is a need for laser annealing technology that can increase production volume without hindering crystal growth and suppressing substrate damage.

[0136] 4. Implementation Method 1

[0137] 4.1 Structure

[0138] The device structure of the laser annealing system in Implementation Method 1 is similar to Figure 2 The laser annealing system 10 shown is the same. In the following description of Embodiment 1, the same laser annealing system 10 will be used. Figure 2 The reference numerals are the same as those shown for the structure.

[0139] In the laser annealing system 10 of Embodiment 1, instead of irradiating with pulsed laser at a predetermined repetition frequency for a predetermined time, such as... Figure 5 As shown, burst irradiation is performed, repeating the burst period Pb and the rest period Ps. The laser annealing control processor 100 and the laser control processor 28 adjust the repetition frequency, pulse energy, pulse number, and rest period length during the burst period of the burst action, thereby controlling the heat input to the irradiated object 160.

[0140] That is, the laser annealing control processor 100 and the laser control processor 28 control the heat storage of the irradiated object 160 in such a way that the surface of the ITO film is kept at a temperature above the crystallization threshold temperature Hcz as much as possible, and the area near the substrate containing the interface between the ITO film and the substrate is kept at a temperature below the damage threshold temperature Hbd.

[0141] The irradiation condition parameters for the burst irradiation associated with heat storage control are adjusted according to the materials and thicknesses of the thin film and the substrate, respectively. Laser annealing control processor 100 and laser control processor 28 are examples of processors in this disclosure.

[0142] Furthermore, in the laser annealing system 10, a cooling mechanism is provided on the lower surface of the substrate to mitigate the damage to the substrate caused by temperature differences in the thickness direction.

[0143] 4.2 Actions

[0144] Regarding the operation of the laser annealing system 10 in Embodiment 1, using Figure 5 to and Figure 4 The differences will be explained in detail. Figure 5This is a graph showing an example of sudden irradiation performed by the laser annealing system 10 of Embodiment 1, and an example of the shift of the thin film surface temperature Hs and interface temperature Hi under sudden irradiation. Figure 5 The vertical and horizontal axes are Figure 4 same.

[0145] like Figure 5 As shown, the laser annealing system 10 irradiates the same portion of the ITO film with pulsed laser light during multiple burst irradiations by alternating burst irradiation periods Pb (for continuous pulsed laser irradiation) and rest periods Ps (for stopping pulsed laser irradiation). The rest period Ps is an example of the "suppression period" of this disclosure.

[0146] The laser annealing control processor 100 and the laser control processor 28 control the heat input and heat storage of the irradiated object 160 by adjusting the irradiation conditions of the burst irradiation, and control the surface temperature Hs and interface temperature Hi of the thin film.

[0147] The irradiation conditions for a burst irradiation include parameters such as the pulse energy, repetition frequency, number of pulses, and length of the rest period Ps within the burst's Pb. Furthermore, the number of pulses within the burst's Pb is related to the length of the burst's Pb. Alternatively, the length of the burst's Pb can be used instead of the number of pulses. For example... Figure 3 As explained, the laser flux was set to be less than the ablation threshold.

[0148] like Figure 5 As shown, through continuous irradiation by multiple pulsed lasers within Pb during the burst period, the surface temperature Hs and interface temperature Hi of the thin film in Pb gradually increase during the burst period, and the state in which the surface temperature Hs is higher than the crystallization threshold temperature Hcz is maintained for a certain period of time.

[0149] Then, during the rest period Ps, the heat input stops, and therefore, during the rest period Ps, the film surface temperature Hs and the interface temperature Hi gradually decrease. During the rest period Ps, the film surface temperature Hs can reach a state below the crystallization threshold temperature Hcz.

[0150] The interface temperature Hi remains below the damage threshold temperature Hbd during both the burst phase (Pb) and the rest phase (Ps). That is, during the burst phase (Pb), although the interface temperature Hi gradually increases, it terminates the burst phase (Pb) before reaching the damage threshold temperature Hbd, transitioning to the rest phase (Ps). Thereafter, the burst phase (Pb) and the rest phase (Ps) repeat.

[0151] 4.3 Functions / Effects

[0152] By using the burst irradiation method of Embodiment 1, the time required to maintain the film surface temperature Hs at or above the crystallization threshold temperature Hcz is minimized, thus reducing the thermal impact on the substrate serving as the base layer. Therefore, according to Embodiment 1, the production rate of annealing treatment for ITO films and IGZO films deposited on substrates with low heat resistance temperatures, such as PET resin and PC, can be increased.

[0153] Furthermore, according to Embodiment 1, laser annealing can be performed at a temperature above the crystallization threshold temperature Hcz on the surface of the thin film and at a temperature below the damage threshold temperature Hbd near the substrate containing the interface between the ITO thin film and the substrate. Therefore, while suppressing substrate damage, the generation and growth of crystal nuclei can be carried out efficiently, and improvements in conductivity, mobility, and other properties of the electrode material are also expected.

[0154] 4.4 Variation 1 of Implementation Method 1

[0155] 4.4.1 Structure

[0156] The structure of the laser annealing system in variation 1 of embodiment 1 is the same as that of laser annealing system 10.

[0157] exist Figure 5 The text explains that laser irradiation can be stopped by reducing the pulse energy to zero during the pause period Ps of the burst irradiation. However, it also states that the pulse energy may not be reduced to zero during a period equivalent to the pause period Ps. That is, as... Figure 6 As shown, instead of the rest period Ps, a low-output period Pd can be used for irradiating a pulsed laser with pulse energy adjusted to be lower than that of the burst period Pb. The low-output period Pd is an example of the "suppression period" in this disclosure.

[0158] 4.4.2 Actions

[0159] Figure 6 This is a graph showing an example of sudden irradiation performed by the laser annealing system 10 of Modified Example 1 of Embodiment 1, and an example of the shift in the surface temperature Hs and interface temperature Hi of the thin film accompanying the sudden irradiation. Figure 6 The vertical and horizontal axes are Figure 3 Same. Can also be used as a substitute. Figure 5 And adopt Figure 6 Such sudden exposure.

[0160] like Figure 6 As shown, the laser annealing control processor 100 and the laser control processor 28 can suppress heat accumulation by making the pulse energy of the pulsed laser to be irradiated less than the pulse energy of the burst period Pb during the low output period Pd, which replaces the rest period Ps. Additionally, although in Figure 6In the example, the pulse energy of Pd during the low output period was set in such a way that the thin film surface temperature Hs in Pd was basically maintained above the crystallization threshold temperature Hcz. However, the thin film surface temperature Hs in Pd during the low output period can also be made lower than the crystallization threshold temperature Hcz by adjusting the pulse energy of Pd during the low output period.

[0161] 4.4.3 Functions / Effects

[0162] According to a variation of embodiment 1, by adjusting the pulse energy of the pulsed laser to be irradiated during the low output period Pd after the burst period Pb, the degree of freedom in controlling the heat storage of the irradiated object 160 can be improved.

[0163] 4.5 Variation 2 of Implementation Method 1

[0164] 4.5.1 Structure

[0165] Figure 7 The structure of the laser annealing system 10A, a variation of Embodiment 1, is shown in schematic form. Regarding... Figure 7 The structure shown is for... Figure 2 The differences will be explained.

[0166] The laser annealing system 10A has a cooling plate 78 on the surface of the stage 76 where the object 160 is placed. The cooling plate 78 can be a structure using water cooling or a Peltier element. The cooling plate 78 is an example of a cooling mechanism in this disclosure. The cooling plate 78 can be connected to the laser annealing control processor 100 to control the on-off state of the cooling. The on-off state of the cooling can be controlled, for example, by opening and closing a valve in the case of water cooling, or by switching the current on and off through the Peltier element.

[0167] Figure 8 It is Figure 7 The image shows an enlarged side view of the cooling plate 78 and the irradiated object 160. The irradiated object 160 has a laminated structure having a heated object 160t under laser irradiation and a non-heatable component 160b for which the thermal effects of laser irradiation are to be minimized. The heated object 160t is a thin film annealed by the laser annealing system 10A, such as an ITO film or an IGZO film. The non-heatable component 160b is a substrate made of a material lacking heat resistance, such as a resin substrate like PET resin or PC.

[0168] 4.5.2 Actions

[0169] The laser annealing control processor 100 controls the cooling action of opening and closing the cooling plate 78 synchronously with the sudden action. Figure 9 This is a timing diagram illustrating a control example of the cooling operation.

[0170] Figure 9 The topmost graph F9A shows the sudden action period Pb and the rest period Ps. The middle graph F9B shows control example 1 of the cooling action of the cooling plate 78, and the bottom graph F9C shows control example 2.

[0171] The timing of cooling activation can be delayed (graph F9B) or advanced (graph F9C) compared to the start timing of Pb during the burst period. The laser annealing control processor 100 adjusts the heat distribution in the thickness direction of the irradiated object 160 by delaying or advancing the cooling activation relative to Pb during the burst period.

[0172] The length of the cooling activation period may not be the same as the Pb during the burst period. The timing of the cooling activation and the length of the cooling activation period are adjusted in a way that achieves the desired heat distribution.

[0173] 4.5.3 Functions / Effects

[0174] The cooling plate 78 can remove heat transferred to the substrate, which is a non-heatable component 160b, and thus can more effectively suppress substrate damage caused by heat.

[0175] According to the laser annealing system 10A, the cooling action performed by using the cooling plate 78 has the effect of controlling the temperature gradient in the thickness direction of the irradiated object 160. Therefore, while preventing the substrate from heating up, it is easy to control the temperature of the film 160t, which is the object to be heated.

[0176] 5. Topic 2

[0177] ITO thin films can easily achieve electrodes with lower resistivity and higher mobility by increasing the grain size during crystallization via laser annealing. It is assumed that the energy required for crystallization from an amorphous state is in the order of [nucleation] > [grain growth]. Therefore, this method was studied to achieve growth in two stages: nucleation and grain growth, using conventional atmosphere annealing.

[0178] However, based on Figure 10 In the laser annealing process involving continuous pulsed laser irradiation, the film surface temperature Hs exceeds the crystallization threshold temperature Hcz and continues to rise. Grain growth occurs above the nucleation threshold temperature, thus continuously generating nuclei, ultimately resulting in smaller grains (see reference). Figure 11 This is because, at temperatures above the nucleation threshold temperature, nuclei are more easily formed compared to crystal growth.

[0179] and Figure 4 same, Figure 10The figure shows the shift of the film surface temperature Hs under continuous pulsed laser irradiation. Figure 11 It is shown schematically in Figure 10 The diagram illustrates the crystallization process of a thin film under continuous pulsed laser irradiation.

[0180] Figure 11 The passage of time is shown from left to right. Figure 11 In the irradiated region Art of the thin film, crystal nuclei Cc are generated and crystals grow over time.

[0181] Figure 11 The left image F11A shows the state where the film surface temperature Hs exceeds the nucleation threshold temperature, resulting in the formation of crystal nuclei Cc. The central image F11B shows the state where the number of crystal nuclei Cc increases and grains grow due to the formation of new crystal nuclei Cc. The right image F11C shows the state where, starting from the state in the central image F11B, the number of crystal nuclei Cc increases and grains Cm grow further through the formation of new crystal nuclei Cc.

[0182] As the number of crystal nuclei Cc increases, the grain size Cm cannot grow to a sufficiently large size, becoming a medium-sized grain Cm. Thus, during continuous irradiation with highly repetitive pulsed lasers, since grain growth occurs above the crystal nucleation threshold temperature, new crystal nuclei Cc will be continuously generated, and the final size of each grain Cm will remain relatively small.

[0183] On the other hand, Figure 12 In a simple burst irradiation pulse like the one shown, new crystal nuclei are generated simultaneously with grain growth. In this case, the crystal orientations of each generated grain are different; therefore, even adjacent grains are difficult to merge and grow together, and thus the grain size does not increase (see reference). Figure 13 and Figure 14 ).

[0184] Figure 12 This is a graph illustrating examples of burst modes and the progression of the film surface temperature Hs accompanying burst irradiation. Figure 12 In the burst irradiation shown, during the burst period of Pb, the film surface temperature Hs rises to a state above the nucleation threshold temperature Hcc, and during the rest period of Ps, the film surface temperature Hs decreases to a state below the crystal growth threshold temperature Hcg. By repeating this burst period of Pb and the rest period of Ps, and intermittently repeating the states where the film surface temperature Hs is above the nucleation threshold temperature Hcc and below the crystal growth threshold temperature Hcg, grain growth occurs simultaneously with the formation of new nuclei.

[0185] Figure 13 It is shown schematically in Figure 12The diagram illustrates the crystallization process of a thin film under sudden irradiation. Figure 13 In the irradiated region Art of the thin film, crystal nuclei Cc are generated and crystals grow over time. Regarding... Figure 13 , to Figure 11 The differences will be explained.

[0186] Figure 13 The left figure F13A shows the state where the thin film surface temperature Hs exceeds the nucleation threshold temperature Hcc, resulting in the formation of crystal nuclei Cc. The central figure F13B shows the following situation: the thin film surface temperature Hs intermittently exceeds the nucleation threshold temperature Hcc and intermittently exceeds the crystal growth threshold temperature Hcg, thereby increasing the number of new crystal nuclei Cc, while the crystal nuclei Cc grow and develop into grains Cb.

[0187] Figure F13C on the right shows the process of further generating new crystal nuclei Cc from the state in the central figure F13B, resulting in the growth of grains Cm and Cb.

[0188] Thus, in Figure 12 During the sudden irradiation shown, the formation of new crystal nuclei Cc and the growth of crystal grains Cm and Cb occur simultaneously.

[0189] Figure 14 schematically showing through Figure 12 The grains shown are formed by sudden irradiation. For example... Figure 14 As shown, through Figure 12 The crystals Cb, Cm1, Cm2, Cm3, and Cm4 generated by the sudden irradiation have different crystal orientations. Therefore, even if the crystals are adjacent to each other, they are difficult to merge and grow together, and the final crystal size is not very large.

[0190] Given this situation, there is a need for laser annealing methods that can increase production without hindering crystal growth.

[0191] 6. Implementation Method 2

[0192] 6.1 Structure

[0193] The device structure of the laser annealing system in Implementation Method 2 is similar to... Figure 2 The laser annealing system 10 shown or Figure 7 The laser annealing system 10A shown is the same. In the following description of Embodiment 2, the same system will be used. Figure 2 The reference numerals are the same as those shown for the structure.

[0194] 6.2 Actions

[0195] The laser annealing system 10 of Embodiment 2 can also make the initial burst period of burst irradiation different from other subsequent burst periods. For example, by making the initial burst period a laser irradiation with higher energy than other subsequent burst periods, the thin film surface temperature Hs is raised to above the nucleation threshold temperature Hcc. In subsequent burst periods, by using low-energy laser irradiation, a temperature above the crystal growth threshold temperature Hcg is achieved while maintaining a thin film surface temperature Hs lower than the nucleation threshold temperature Hcc. Thus, crystal growth can be performed in two stages. In addition, the initial burst period of high-energy laser irradiation can also be multiple burst periods including the initial burst period.

[0196] Figure 15 This is a graph showing an example of sudden irradiation of the laser annealing system 10 of Embodiment 2, and an example of the change in the surface temperature Hs of the thin film accompanying the sudden irradiation. Figure 15 The vertical and horizontal axes are Figure 12 same.

[0197] like Figure 15 As shown, the laser annealing control processor 100 ensures that the pulse energy of Pb1 during the initial burst period of a burst action is higher than the pulse energy of Pb2 during the next burst period. The repetition frequency in Pb1 and Pb2 during each burst period can be the same.

[0198] During the initial burst period, laser irradiation of Pb1 causes the film surface temperature Hs to reach a state above the nucleation threshold temperature Hcc, thus generating crystal nuclei. Then, laser irradiation is controlled as follows: the pulse energy in other burst periods, including the next (second) burst period Pb2, is set lower than the pulse energy of the initial burst period Pb1; the film surface temperature Hs is maintained at a temperature lower than the nucleation threshold temperature Hcc during other burst periods; and the time for which the film surface temperature Hs is maintained above the crystal growth threshold temperature Hcg is extended as much as possible. The laser irradiation conditions (pulse energy, repetition frequency, and number of pulses) applied to subsequent burst periods can be identical. Therefore, crystal growth can be achieved in two stages: nucleation and grain growth.

[0199] Figure 16 It is shown schematically in Figure 15 The diagram illustrates the crystallization process of a thin film under sudden irradiation. (About...) Figure 16 , to Figure 13 The differences will be explained.

[0200] Figure 16Left Figure F16A shows the state of crystal nuclei Cc generated by laser irradiation of Pb1 during the initial burst period. Then, as shown in the central Figure F16B, the generation of new crystal nuclei Cc is suppressed by laser irradiation of Pb2 during the second burst period, and the existing crystal nuclei Cc grow into grains Cm. Furthermore, as shown in the right Figure F16C, the generation of new crystal nuclei Cc is suppressed by laser irradiation during the third and subsequent burst periods, and the existing grains Cm grow into larger grains Cb.

[0201] 6.3 Functions / Effects

[0202] According to Embodiment 2, the crystal can be grown in two stages, thus making it easy to obtain large-sized crystals with high mobility.

[0203] 6.4 Variation 1 of Implementation Method 2

[0204] The burst period on the initiation side is not limited to changing the pulse energy relative to other burst periods. For example, the burst period on the initiation side can also be set to a different repetition frequency than other burst periods. For instance, the burst period on the initiation side can also be set to a higher repetition frequency than other burst periods (see [reference]). Figure 17 ).

[0205] Figure 17 Examples of sudden irradiation of a variation of Embodiment 2, Example 1, and examples of the change in the surface temperature Hs of the thin film accompanying sudden irradiation are shown. Figure 17 The vertical and horizontal axes are Figure 15 same.

[0206] like Figure 17 As shown, the laser annealing control processor 100 makes the repetition frequency of Pb1 during the initial burst period of the burst action higher than the repetition frequency of Pb2 during the next burst period. The pulse energy in Pb1 and Pb2 during each burst period can be the same.

[0207] During the initial burst period, laser irradiation of Pb1 causes the film surface temperature Hs to reach a state above the nucleation threshold temperature Hcc, thus generating crystal nuclei. Then, laser irradiation is controlled as follows: the repetition frequency in subsequent burst periods, including the next (second) burst period Pb2, is set lower than the repetition frequency of the initial burst period Pb1; the film surface temperature Hs is maintained at a temperature lower than the nucleation threshold temperature Hcc during these subsequent burst periods; and the time for which the film surface temperature Hs is maintained above the crystal growth threshold temperature Hcg is extended as much as possible. The laser irradiation conditions (pulse energy, repetition frequency, and pulse number) applied to subsequent burst periods can be identical. Therefore, crystal growth can be achieved in two stages: nucleation and grain growth.

[0208] 6.5 Variation 2 of Implementation Method 2

[0209] For the initial burst period, the number of pulses (burst duration) can also be set to differ from other burst periods. For example, compared to other burst periods, the number of pulses during the initial burst period can be increased (see reference). Figure 18 At this point, the rest period following the initial burst can also be set to a different length than other rest periods.

[0210] Figure 18 Examples of sudden irradiation in a variation of Embodiment 2 are shown, as well as examples of the shift in the surface temperature Hs of the thin film accompanying sudden irradiation. Figure 18 The vertical and horizontal axes are Figure 15 same.

[0211] like Figure 18 As shown, the laser annealing control processor 100 can also make the number of pulses in the initial burst period Pb1 of a burst action greater than the number of pulses in the next burst period Pb2. The pulse energy and repetition frequency in each burst period Pb1 and Pb2 can be the same.

[0212] In addition, the laser annealing control processor 100 can also set the rest period Ps1 immediately after the initial burst period Pb1 to be longer than other rest periods Ps2.

[0213] Through this sudden irradiation, and Figure 15 and Figure 17 Similarly, it is possible to grow crystals in two stages.

[0214] 6.6 Other

[0215] Implementation method 2 and its variations 1 and 2 can be appropriately combined. For example, the laser annealing control processor 100 may also set the laser irradiation of Pb1 during the initial burst period to have high energy and high repetition frequency compared to other burst periods. Furthermore, for example, the laser annealing control processor 100 may also set the laser irradiation of Pb1 during the initial burst period to have high energy but low repetition frequency compared to other burst periods, or it may set the laser irradiation of Pb1 during the initial burst period to have high repetition frequency but fewer pulses compared to other burst periods.

[0216] Furthermore, it is also possible to set part or all of the pause period in Implementation Method 2 and its variations 1 and 2 as Figure 6 Pd during that low output period.

[0217] 7. Implementation Method 3

[0218] 7.1 Structure

[0219] Figure 19 The structure of the laser annealing system 10B according to Embodiment 3 is shown in schematic. The laser annealing system 10B is a system for annealing a mesh-like irradiated object R1 using a roll-to-roll process. The irradiated object R1 may be, for example, a resin roller on which a thin film is formed on a resin substrate.

[0220] like Figure 19 As shown in the central figure F19A, the laser annealing system 10B has a conveying mechanism (not shown) for conveying the irradiated object R1 in a roller-to-roll manner, a laser device L1, and a distribution optical system including multiple beam splitters BS1, BS2, BS3, BS4 for distributing the pulsed laser PL1 output from the laser device L1 to multiple irradiation areas AR1, AR2, AR3, AR4.

[0221] exist Figure 19 The diagram shows a structure with four illumination regions AR1, AR2, AR3, and AR4; however, the number of illumination regions is not limited to this example. The number of beam splitters also varies depending on the number of illumination regions.

[0222] The conveying mechanism includes known structures such as the take-up roller, the winding roller, and the transfer roller.

[0223] Multiple irradiation zones AR1, AR2, AR3, and AR4 are areas where pulsed lasers irradiate the object R1. The pulsed lasers are distributed by arranging these zones at predetermined intervals along the direction of movement of the object R1. The areas between irradiation zones AR1 and AR2, AR2 and AR3, and AR3 and AR4, which are spaced apart by predetermined intervals, are designated as intermittent areas ARs where no laser irradiation occurs.

[0224] The pulsed laser PL1 output from the laser device L1 is branched by beam splitters BS1, BS2, BS3, and BS4, and incident on the irradiation areas AR1, AR2, AR3, and AR4, respectively. The reflectivity of each beam splitter BS1, BS2, BS3, and BS4 is set in a manner that ensures equal laser energy in each irradiation area AR1, AR2, AR3, and AR4. Alternatively, the final beam splitter BS4 can also be a mirror.

[0225] In the laser annealing system 10B, the irradiated object R1 moves at a low speed. The moving speed of the irradiated object R1 is set such that the rest period is the time to pass through the intermittent regions ARs. Furthermore, the number of irradiations per part is determined by the width of the irradiated area in the moving direction, the moving speed of the irradiated object R1, and the repetition frequency.

[0226] 7.2 Actions

[0227] During the movement of the object R1 being irradiated via a roller-to-roll method, the laser device L1 continuously outputs pulsed laser PL1 at a constant repetition frequency. Figure 19 The graph F19B shows the pulse energy of the pulsed laser PL1 output from the laser device L1.

[0228] Figure 19 Enlarged view F19C is an explanatory diagram showing the laser irradiation result when pulsed laser is continuously irradiated in irradiation area AR1. In the laser annealing system 10B, the position of the irradiating beam is fixed in each irradiation area AR1 to AR4. However, since the irradiated object R1 moves along the roller travel direction (moving direction), the part of the irradiated laser moves relatively, and the irradiation range of each beam overlaps (see enlarged view F19C).

[0229] Therefore, the number of times a certain part (the same part) is irradiated is determined based on the beam width in the moving direction on the irradiated object R1, the moving speed (roller travel speed), and the repetition frequency of the pulsed laser PL1. By setting multiple irradiation areas AR1, AR2, AR3, and AR4, and setting intermittent areas between them, each area on the irradiated object R1 is irradiated by the same burst pulse as in Embodiment 1.

[0230] Figure 19 The graph F19D shows an example of a burst pulse of pulsed laser light irradiating the same part of the irradiated object R1.

[0231] By dividing the area into multiple irradiation zones AR1, AR2, AR3, AR4 and multiple intermittent zones ARs in between, and by moving the roller, each part of the irradiated object R1 is irradiated by a burst pulse as shown in the curve F19D. Thus, burst irradiation can be performed in the same way as the laser device 12 in Embodiment 1.

[0232] The laser annealing system 10B can perform this annealing process on the resin substrate after a thin film has been formed on the resin substrate, while the resin substrate is being wound onto a roller.

[0233] Furthermore, the upstream and downstream portions of each of the irradiation areas AR1, AR2, AR3, and AR4 receive fewer irradiations and therefore may not be used as components. Here, "upstream side" refers to the side upstream of the irradiated object R1 in the direction of its movement. Figure 19 The left side of the middle finger.

[0234] 7.3 Examples of Conveying Mechanisms

[0235] Figure 20This is a perspective view showing an example of a roll-to-roll conveying mechanism M used in a laser annealing system 10B. The conveying mechanism M has a winding section 302 and a winding section 304, with a film-forming section 306 and a laser annealing treatment section 310 disposed between the winding section 302 and the winding section 304. The film-forming section 306 is a processing section for forming thin films such as ITO on a substrate fed from the winding section 302. The laser annealing treatment section 310 is disposed downstream of the film-forming section 306 and is located on... Figure 20 The part indicated by the arrow is the processing section where laser irradiation is performed during the annealing process. Figure 20 The specific structure of the laser annealing unit 310 is not illustrated, however, the laser annealing unit 310 includes... Figure 19 The multiple irradiation areas AR1, AR2, AR3, and AR4 are described in the text. The laser annealing processing unit 310 includes structures such as the optical system required for laser irradiation.

[0236] With this structure, in the roll-to-roll process, annealing can be performed midway through the winding of the roll after the film has been formed.

[0237] In addition, the conveyor mechanism M can also replace Figure 7 and Figure 8 The cooling plate 78 described herein has cooling rollers (not shown). The cooling rollers can be disposed on the back side of the substrate in multiple irradiation areas AR1, AR2, AR3, and AR4, respectively.

[0238] 7.4 Functions / Effects

[0239] According to embodiment 3, in the roll-to-roll method, annealing can be performed simultaneously with the roll winding. Therefore, compared to annealing that stops winding, the processing time can be shortened.

[0240] 7.5 Variation 1 of Implementation Method 3

[0241] 7.5.1 Structure

[0242] Figure 21 This is an explanatory diagram showing the structure and operation of the laser annealing system 10C, a variation of Embodiment 3. Regarding... Figure 21 The structure shown is for... Figure 19 The differences will be explained. Figure 21 The schematic top view F21A shown above illustrates an example of multiple irradiation areas AR1, AR2, AR3... in the laser annealing system 10C. Although the illustration is omitted, it is consistent with... Figure 19 Similarly, the laser annealing system 10C has a laser device L1 and multiple beam splitters that direct pulsed laser light into multiple irradiation areas AR1, AR2, AR3... respectively.

[0243] In the laser annealing system 10C, corresponding to Embodiment 2, when growth is carried out in two stages, a region irradiated with a burst pulse of high energy and high repetition frequency is arranged in the upstream part of multiple irradiation regions AR1, AR2, AR3...

[0244] exist Figure 21 The diagram illustrates an example where the initial irradiation region AR1 is irradiated with a pulsed laser of higher energy than other irradiation regions. In this case, for example, the reflectivity of the upstream beam splitter can be set to be higher than that of other beam splitters, thereby distributing more energy.

[0245] Figure 21 The lower layer, plot F21B, is a graph illustrating an example of sudden irradiation of the laser annealing system 10C, and an example of the shift in the thin film surface temperature Hs under sudden irradiation. Figure 21 The diagram illustrates the burst periods corresponding to each of the initial irradiation area AR1 through the third irradiation area AR3; however, the burst periods corresponding to the fourth and subsequent irradiation areas are also shown in the diagram. (Graph F21B and...) Figure 15 The curves described are the same.

[0246] 7.5.2 Actions

[0247] The laser irradiation operation in the laser annealing system 10C is the same as in Embodiment 3. Through burst irradiation by the laser annealing system 10C, the crystal is grown in two stages, similar to Embodiment 2.

[0248] 7.5.3 Function / Effect

[0249] According to the laser annealing system 10C, in the roll-to-roll process, the crystal can be grown in two stages, resulting in a crystal with high mobility.

[0250] 7.6 Variation 2 of Implementation Method 3

[0251] 7.6.1 Structure

[0252] Figure 22 The structure of the laser annealing system 10D, a variation of Embodiment 3, is shown in schematic form. Regarding... Figure 22 The structure shown is for... Figure 19 The differences will be explained.

[0253] Laser annealing system 10D replacement Figure 19 The laser device L1 has multiple laser devices L2 and L3. Furthermore, the laser annealing system 10D replaces... Figure 19 The beam splitters BS1 to BS4 include beam splitter BS5, reflector RM1, beam splitter BS6, and reflector RM3. Other structures can be combined with... Figure 19same.

[0254] There are situations where high pulse energy and high repetition frequency are required depending on the width of the roller, the number of irradiation areas, or the location of the irradiation areas. In such cases, it is possible to... Figure 22 Multiple laser devices L2 and L3 are configured to distribute pulsed lasers to different irradiation areas AR1, AR2, AR3, and AR4 respectively.

[0255] 7.6.2 Actions

[0256] Laser devices L2 and L3 are controlled to synchronously output pulsed lasers PL2 and PL3. The pulsed laser PL2 output from laser device L2 is split into two directions by beam splitter BS5. One pulsed laser is incident on the irradiation area AR1, and the other pulsed laser is reflected by mirror RM1 and incident on the irradiation area AR2. For example, the irradiation area AR1 can be irradiated with a higher pulsed laser energy relative to the irradiation area AR2. Furthermore, laser device L2 can have a higher repetition rate relative to laser device L3.

[0257] Similarly, the pulsed laser PL3 output from laser device L3 is split into two directions by beam splitter BS6. One pulsed laser is incident on the irradiation area AR3, and the other pulsed laser is reflected by mirror RM2 and incident on the irradiation area AR4. Other actions are the same as... Figure 19 same.

[0258] 7.6.3 Functions / Effects

[0259] The laser annealing system 10D achieves the same effect as the laser annealing system 10B. Furthermore, the laser annealing system 10D allows for the distribution of pulsed laser energy with desired pulses to each irradiation area. Moreover, since multiple laser devices are used, pulsed lasers with desired repetition frequencies can be irradiated to each irradiation area.

[0260] 8. Implementation Method 4

[0261] 8.1 Structure

[0262] Figure 23 The structure of the laser annealing system 10E according to Embodiment 4 is shown in schematic. The laser annealing system 10E has multiple laser devices L4, L5, L6, L7, and L8 instead of laser device 12. Laser devices L4, L5, L6, L7, and L8 may each have the same structure as laser device 12.

[0263] The laser annealing system 10E includes mirrors RMa, RMBb, RMc, and RMd that guide pulsed lasers PL4, PL5, PL6, PL7, and PL8 output from laser devices L4, L5, L6, L7, and L8 to the irradiation area AR12. The pulsed laser optical path guiding each pulsed laser PL4, PL5, PL6, PL7, and PL8 to the irradiation area AR12 may include optical elements such as mirrors (not shown) other than the mirrors RMa, RMBb, RMc, and RMd.

[0264] The irradiated area AR12 can be Figure 2 The area on stage 76 described in the text can also be Figure 19 The irradiation areas described are AR1, AR2, AR3, and AR4.

[0265] In addition, Figure 23 The diagram shows a structure using five laser devices L4 to L8; however, the number of laser devices is not limited to this example.

[0266] 8.2 Actions

[0267] High repetitive irradiation in the irradiation area AR12 can also be achieved by controlling the output timing delay of each pulse laser output by multiple laser devices L4 to L8.

[0268] Figure 24 This is a graph illustrating an example of burst irradiation achieved by the laser annealing system 10E. (Example) Figure 24 As shown, by staggering the output timing of the pulsed lasers PL4 to PL8 from the optical devices L4 to L8 so that they irradiate the same irradiation area AR1, burst irradiation that is essentially the same as a high-repetition burst action can be performed.

[0269] For example, when each laser device L4 to L8 operates at a repetition frequency of 200Hz, by staggering the timing of the outputs of these five laser devices L4 to L8 to irradiate the same area, it is possible to simulate irradiation at 1kHz.

[0270] 8.3 Functions / Effects

[0271] According to the laser annealing system 10E of embodiment 4, burst irradiation can be achieved by using a repetition frequency that is higher than the repetition frequency of each laser device L4 to L8.

[0272] 9. Other uses besides ITO film

[0273] The technology disclosed herein can also be applied to the following purposes.

[0274] [1] Annealing treatment for crystallization of a-Si channel materials

[0275] [2] Used for annealing (magnetization process) to alloy the metal materials together after depositing multiple metal films on a substrate such as a resin film that lacks heat resistance.

[0276] [3] Annealing treatment for crystal recovery after ion implantation in semiconductor processes

[0277] [4] Control of thermal diffusion of dopant material toward substrate depth

[0278] [5] Annealing treatment when heat treatment is performed on coating materials such as hard coatings on films, etc.

[0279] [6] Annealing treatment for reducing resistance caused by die expansion in metal wiring on semiconductor chips or printed circuit boards

[0280] 10. About the processor

[0281] Processors such as laser control processor 28 and laser annealing control processor 100 can also be physically configured in hardware to execute the various processes included in this disclosure. For example, a processor can also be a computer that includes a memory storing control programs that define various processes and a processing device for executing the control programs. The control programs can be stored in a single memory or separately in multiple physically separate memories, and the various processes are defined by the control programs as a collection of these memories. The processing device can be a general-purpose processing device such as a CPU or a special-purpose processing device such as a GPU.

[0282] Furthermore, the processor can also be programmed in software to perform the various processes contained in this disclosure. For example, the processor's ability to perform various processes can also be implemented in a special-purpose device such as an ASIC or a programmable device such as an FPGA.

[0283] The various processes included in this disclosure can be executed by a single computer, a single dedicated device, or a single programmable device, or can be executed collaboratively by multiple physically separate computers, multiple dedicated devices, or multiple programmable devices. The various processes can also be executed by a combination of at least two of more than one computer, more than one dedicated device, and more than one programmable device.

[0284] 11. Other

[0285] The foregoing description is not limiting, but merely illustrative. Therefore, those skilled in the art will understand that modifications can be made to embodiments of this disclosure without departing from the claims. Furthermore, those skilled in the art will understand that embodiments of this disclosure can be combined.

[0286] Unless explicitly stated otherwise, all terms used in this specification and claims should be interpreted as "non-limiting." For example, terms such as "comprising," "having," "possessing," and "having" should be interpreted as "not excluding the presence of structural elements other than those described." Furthermore, the modifier "a" should be interpreted as meaning "at least one" or "one or more." Additionally, terms such as "at least one of A, B, and C" should be interpreted as "A," "B," "C," "A+B," "A+C," "B+C," or "A+B+C." Moreover, it should be interpreted as including combinations of these elements with parts other than "A," "B," and "C."

Claims

1. A laser annealing system, which anneals a thin film on a substrate by irradiating the thin film with a pulsed laser, wherein, The laser annealing system has the following features: A laser device that outputs the pulsed laser; An optical system that irradiates the thin film with the pulsed laser; and The processor controls the irradiation of the same portion of the thin film by performing burst irradiation that repeats during a burst period of continuous irradiation of the pulsed laser and a suppression period of suppressing the irradiation of the pulsed laser.

2. The laser annealing system according to claim 1, wherein, The flux of the pulsed laser irradiating the thin film is less than the ablation threshold of the thin film.

3. The laser annealing system according to claim 1, wherein, The processor controls the flux in such a way that the flux of the pulsed laser irradiating the thin film is less than the ablation threshold of the thin film.

4. The laser annealing system according to claim 1, wherein, The irradiation conditions for the burst irradiation are set as follows: during the burst period, the surface temperature of the thin film exceeds the crystallization threshold temperature of the thin film, and during both the burst period and the suppression period, the temperature of the interface between the thin film and the substrate is maintained below the damage threshold temperature of the substrate.

5. The laser annealing system according to claim 4, wherein, The irradiation conditions include at least one of the following parameters during the burst period: pulse energy, repetition frequency, number of pulses, length of the suppression period, and number of bursts of the pulsed laser.

6. The laser annealing system according to claim 1, wherein, The processor controls the burst irradiation operation in such a way that during the burst, the surface temperature of the thin film exceeds the crystallization threshold temperature of the thin film, and during both the burst and the suppression periods, the temperature of the interface between the thin film and the substrate is maintained below the damage threshold temperature of the substrate.

7. The laser annealing system according to claim 1, wherein, The laser annealing system has a cooling mechanism for cooling the substrate.

8. The laser annealing system according to claim 1, wherein, The pulsed laser of the initial burst in one of the multiple bursts irradiates with a higher pulse energy, a higher repetition frequency, or a greater number of pulses than the pulsed laser of other bursts.

9. The laser annealing system according to claim 8, wherein, The suppression period immediately following the end of the initial burst period is longer than the other suppression periods.

10. The laser annealing system according to claim 8, wherein, The irradiation conditions for the burst irradiation are set as follows: during the initial burst period, the surface temperature of the film is made to exceed the nucleation threshold temperature of the film; during the other burst periods, the surface temperature of the film is maintained below the nucleation threshold temperature; and during the other burst periods, the surface temperature of the film is made to exceed the crystal growth threshold temperature of the film.

11. The laser annealing system according to claim 8, wherein, The processor controls the burst irradiation operation in such a way that during the initial burst period, the surface temperature of the thin film exceeds the nucleation threshold temperature of the thin film, during the other burst periods, the surface temperature of the thin film is maintained below the nucleation threshold temperature, and during the other burst periods, the surface temperature of the thin film exceeds the crystal growth threshold temperature of the thin film.

12. The laser annealing system according to claim 1, wherein, The suppression period is either a pause period during which the pulsed laser is stopped, or a low-output period during which the pulsed laser has a lower pulse energy than the burst period.

13. The laser annealing system according to claim 1, wherein, The laser annealing system includes a conveying mechanism that conveys the substrate via a roller-to-roll method. The subject is subjected to burst irradiation while the substrate is moved by the conveying mechanism.

14. The laser annealing system according to claim 13, wherein, Multiple irradiation zones are arranged at predetermined intervals along the direction of movement of the irradiated object, for the pulsed laser to irradiate the irradiated object.

15. The laser annealing system according to claim 14, wherein, The processor controls the number of times each of the same locations is irradiated based on the moving speed of the irradiated object, the width of the irradiated area, and the repetition frequency of the pulsed laser.

16. The laser annealing system according to claim 14, wherein, The laser annealing system has a beam splitter that distributes the pulsed laser output from the laser device to the plurality of irradiation areas.

17. The laser annealing system according to claim 14, wherein, The processor adjusts the irradiation conditions in such a way that the surface temperature of the thin film is made above the nucleation threshold temperature by irradiation with the pulsed laser in the upstream irradiation region of the plurality of irradiation regions.

18. The laser annealing system according to claim 17, wherein, The processor adjusts the irradiation conditions in the following manner: by irradiating the thin film with the pulsed laser in the irradiation area outside the upstream irradiation area, the surface temperature of the thin film is made to be above the crystal growth threshold temperature, and the surface temperature of the thin film is maintained below the crystal nucleation threshold temperature.

19. The laser annealing system according to claim 1, wherein, The laser annealing system has multiple laser devices. The processor controls the output timing delay of each pulse laser output by the multiple laser devices.

20. A laser annealing method, wherein the thin film on a substrate is annealed by irradiating it with a pulsed laser, wherein, The laser annealing method includes the following steps: The pulsed laser is output from the laser device; The pulsed laser is irradiated onto the thin film via an optical system; and The same portion of the thin film is irradiated with the pulsed laser by repeating a burst irradiation period during which the continuous irradiation of the pulsed laser is performed and a suppression period during which the irradiation of the pulsed laser is suppressed.

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