Patent Publication Number: US-2019198364-A1

Title: Excimer laser annealing apparatus

Description:
RELATED APPLICATIONS 
     This application is a continuation application of PCT Patent Application No. PCT/CN2018/074344, filed Jan. 26, 2018, which claims the priority benefit of Chinese Patent Application No. CN 201711449637.9, filed Dec. 27, 2017, which is herein incorporated by reference in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates to a display technology field, and more particularly to an excimer laser annealing apparatus. 
     BACKGROUND OF THE DISCLOSURE 
     Excimer laser annealing (ELA) technology has been widely used in the semiconductor industry. In the conventional ELA apparatus manufacturing process, the laser beam is generally focused by the optical system and then irradiated onto the silicon substrate at an oblique angle. A part of the laser beam is absorbed by silicon and a part of the laser beam is reflected by the silicon film to the beam current consumer. The beam current consumer almost absorbed all the energy of the reflected light, and the light energy into heat, resulting in the utilization of energy is not high and will lead to the temperature rise of the beam current consumer, thus affecting the life of the excimer laser annealing apparatus. 
     SUMMARY OF THE DISCLOSURE 
     The purpose of the present disclosure is to provide an excimer laser annealing, which solves the technical problem of increasing the temperature of the beam current consumer. 
     The present disclosure provides an excimer laser annealing apparatus for laser annealing a substrate, including a beam current consumer, a focusing lens, and a laser. The beam current consumer is disposed between the substrate and the laser, the focusing lens is disposed between the beam current consumer and the laser and is located on the optical path of the laser beam of the laser directed onto the substrate, the focus of the focusing lens is on the optical path of the laser beam of the laser directed onto the substrate and on the substrate, the beam current consumer is provided with a transmission cavity running through the beam current consumer and a reflection cavity connecting with the transmission cavity, the reflection cavity includes a surface provided with a reflection film, the surface faces the substrate, the laser beam generated by the laser is focused by the focusing lens and then emitted to the substrate through the transmission cavity, the substrate reflects the focused laser beam onto the reflective film and is reflected back to the substrate via the reflective film. 
     The surface of the reflecting cavity includes an arc-shaped surface, the reflective film is an arc-shaped film, the reflective film is attached to the arc-shaped surface, a center of the arc-shaped surface is located on the optical path of the laser beam of the laser directed onto the substrate and is located on the substrate. 
     The reflective film includes a first thin film layer and a second thin film layer alternately arranged in layers, and the first thin film layer is disposed on an outermost layer and an innermost layer of the reflective film, the first film layer has a first refractive index, the second film layer has a second refractive index, and the first refractive index is greater than the second refractive index. 
     The first thin film layer and the second thin film layer have a same thickness. 
     The thicknesses of the first thin film layer and the second thin film layer are both an integral multiple of a quarter of a wavelength of the laser. 
     The first thin film layer includes at least one of a silicon nitride film layer, a titanium dioxide film layer, a tantalum pentoxide thin film layer, a zirconium oxide thin film layer, a lanthanum titanate thin film layer, a hafnium oxide thin film layer, and a zinc selenide thin film layer. 
     The second thin film layer includes at least one of a magnesium fluoride thin film layer, a silicon oxide thin film layer, an aluminum oxide thin film layer, and a titanium nitride thin film layer. 
     The excimer laser annealing apparatus includes an energy meter for detecting the energy of the laser reflected by the reflection film. 
     The excimer laser annealing apparatus includes a supporter that supports the substrate. 
     The substrate is an amorphous silicon substrate. 
     To sum up, the reflective film of the present disclosure reflects the reflected light beam reaching the reflective film, thereby reducing the absorption of the laser light by the beam current consumer and solving the technical problem that the temperature of the current consumer increases, so that the cooling device for the beam current consumer is omitted; meanwhile, the laser beam reflected by the reflective film is irradiated onto the substrate again, thereby improving the utilization rate of the laser beam. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To describe the technical solutions in the embodiments of the present disclosure or in the prior art more clearly, the following briefly introduces the accompanying drawings required for describing the embodiments or the prior art. Apparently, the accompanying drawings in the following description show merely some embodiments of the present disclosure, and a person of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts. 
         FIG. 1  is a schematic structural diagram of an excimer laser annealing apparatus according to an embodiment of the present disclosure. 
         FIG. 2  is a schematic structural diagram of the reflective film in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The technical solutions in the embodiments of the present disclosure will be described clearly and completely hereinafter with reference to the accompanying drawings in the embodiments of the present disclosure. Apparently, the described embodiments are merely some but not all embodiments of the present disclosure. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present disclosure without creative efforts shall fall within the protection scope of the present disclosure. 
     The present disclosure provides an excimer laser annealing apparatus for laser annealing a substrate  10 , including a beam current consumer  20 , a focusing lens  30 , and a laser  40 . The beam current consumer  20  is between the substrate  10  and the laser  40 , the focusing lens  30  is disposed between the beam current consumer  20  and the laser  40  and located on the optical path of the laser beam of the laser  40  directed onto the substrate  10 . The focus of the focusing lens  30  is on the optical path of the laser beam of the laser  40  directed onto the substrate  10  and on the substrate  10 . The beam current consumer  20  is provided with a transmission cavity  201  penetrating the beam current consumer  20  and a reflection cavity  202  connecting with the transmission cavity  201 . The reflective cavity  202  includes a surface  203  provided with a reflective film  50 , the surface  203  faces the substrate  10 , the laser beam generated by the laser  40  is focused by the focusing lens  30  and then emitted to the substrate  10  through the transmission cavity  201 , the substrate  10  reflects the focused laser beam onto the reflective film  50  and then reflects the laser beam back onto the substrate  10  through the reflective film  50 . The reflective film  50  of the present disclosure reflects the reflected laser beam reaching the reflective film  50  to reduce the absorption of the laser beam by the beam current consumer  20  and solve the technical problem that the temperature of the beam current consumer  20  rises. And further the cooling device for the beam current consumer  20  is omitted. At the same time, the laser beam reflected by the reflection film  50  irradiates the substrate  10  again, which improves the utilization rate of the laser beam. 
     In this embodiment, the substrate  10  is an amorphous silicon substrate, and after laser annealing by the excimer laser annealing device, the substrate  10  is crystallized into a polycrystalline silicon substrate. The substrate  10  is supported by a supporter  60 . The focusing lens  30  is a convex lens. The focused laser beam irradiates the substrate  10  in a direction that is 7 degrees from the perpendicular of the substrate  10 . The transmission cavity  201  is a cavity penetrating the beam current consumer  20 . The reflection cavity  202  is a fan-shaped cavity. The transmission cavity  201  is a chamber through which the laser beam generated by the laser  40  passes in the beam current consumer  20 . The reflection cavity  202  is a cavity in the beam current consumer  20  through which the laser beam reflected by the substrate  10  passes, and the reflection cavity  202  is a cavity in the beam current consumer  20  through which the laser beam reflected by the reflection film  50  passes. 
     In this embodiment, the surface  203  of the reflection cavity  202  is an arc-shaped surface, the reflection film  50  is an arc-shaped film, the reflection film  50  is attached to the arc-shaped surface, the center of the arc-shaped surface reaches the position of the substrate  10  after the laser beam is focused. Specifically, the arc-shaped reflective film  50  is attached to the arc-shaped surface of the beam current consumer  20 , and the center of the arc-shaped curved surface is located on the optical path of the substrate  10  when the laser beam of the laser  40  is located on the substrate  10 , that is, the center of the arc-shaped reflective film  50  is also located on the optical path of the laser beam of the laser  40  directed onto the substrate  10  and on the substrate  10 . The arc-shaped reflection film  50  realizes that the laser beam reflected to the reflection film  50  is reflected to the substrate  10  along the reverse direction that the laser beam reaches the reflection film  50 , and the laser beam reflected by the reflection film  50  can irradiate the center position of the reflection film  50 , the laser beam irradiating the substrate  10  and emitted by the laser  40  irradiates the same position of the substrate  10  to improve the utilization rate of the laser beam. However, since the energy of the laser beam is attenuated during the reflection of the laser beam, when the laser beam reflected by the reflection film  50  is irradiated to the substrate  10 , the energy of the laser beam is already small. Furthermore, when the laser beam is further reflected by the substrate  10  and irradiated to the laser  40 , the energy of the laser beam will be smaller and the laser  40  will not be affected. 
     Please refer to  FIG. 2 , the reflective film  50  includes a first film layer  501  and a second film layer  502  that are alternately stacked, and the first film layer  501  is disposed on the outermost layer and the innermost layer of the reflective film  50 . The first thin film layer  501  has a first refractive index, the second thin film layer  502  has a second refractive index, and the first refractive index is greater than the second refractive index. Specifically, the reflective film  50  includes a first film layer  501  and a second film layer  502 . The first film layer  501  and the second film layer  502  are alternately stacked, and the innermost layer and the outermost layer of the reflective film  50  are both the first film layer  501 . That is, the laser beam reflected by the substrate  10  first comes into contact with the first thin film layer  501  having the first refractive index, since the refractive index of the first thin film layer  501  is greater than the refractive index of the second thin film layer  502 , part of the laser light reaching the first thin film layer  501  is reflected and partially refracted, the laser beam entering the second thin film layer  502  is further reflected and refracted until reaching the first thin film layer  501  in contact with the arcuate curved surface of the reflective cavity  202 . 
     In this embodiment, the thickness of the first film layer  501  and the thickness of the second film layer  502  are equal. The thicknesses of the first thin film layer  501  and the second thin film layer  502  are both integral multiples of a quarter of the laser wavelength. Specifically, the first thin film layer  501  and the second thin film layer  502  have the same thickness and a positive integral multiple of a quarter of the laser wavelength. Since under this condition, the reflected light vectors and the vibration directions of the respective laminated layers are the same, the amplitude of the synthesized reflected light increases as the number of thin film layers increases and the energy increases, the energy of the laser beam reflected by the reflective film  50  and irradiated onto the substrate  10  is still high, thereby further improving the utilization rate of the laser beam. Furthermore, as the number of thin film layers increases, the refracted light entering the beam current consumer  20  after refraction is reduced, the influence on the beam current consumer  20  is small, and the cooling device of the beam current consumer  20  is omitted. 
     In this embodiment, the first thin film layer  501  includes a silicon nitride film layer, a titanium dioxide film layer, a tantalum pentoxide film layer, a zirconium oxide film layer, a lanthanum titanate film layer, a hafnium oxide film layer, and a zinc selenide film layer. The second thin film layer  502  includes a magnesium fluoride thin film layer, a silicon oxide thin film layer, an aluminum oxide thin film layer and a titanium nitride thin film layer. Therefore, during the staggered stacking of the first thin film layer  501  and the second thin film layer  502 , the first thin film layer  501  may be one of a silicon nitride film layer, a titanium dioxide film layer, a tantalum pentoxide thin film layer, a zirconium oxide thin film layer, a lanthanum titanate thin film layer, a hafnium oxide thin film layer and a zinc selenide film layer, or a combination of any several of them. The second thin film layer  502  may be one of a magnesium fluoride thin film layer, a silicon oxide thin film layer, an aluminum oxide thin film layer and a titanium nitride thin film layer, or a combination of any several of them. 
     The excimer laser annealing apparatus includes an energy meter (not shown in the figure) for detecting the energy of the laser light reflected. Specifically, the energy meter is disposed in the beam current consumer  20  at a position close to the reflection film  50 . The energy meter is used for detecting the energy of the laser light reflected by the reflective film  50  and further determining the number of layers of the first film layer  501  and the second film layer  502  in the reflective film  50 . 
     The above disclosure is only the preferred embodiments of the present disclosure, and certainly can not be used to limit the scope of the present disclosure. Persons of ordinary skill in the art may understand that all or part of the procedures for implementing the foregoing embodiments and equivalent changes made according to the claims of the present disclosure still fall within the scope of the present disclosure.