JP7534892B2 - Laser annealing apparatus, laser annealing method, and method for manufacturing semiconductor device - Google Patents

Description

The present invention relates to a laser annealing device, a laser annealing method, and a method for manufacturing a semiconductor device.

Patent Document 1 discloses a laser annealing device for forming a polycrystalline silicon thin film. In Patent Document 1, a linearly polarized laser light is emitted from a solid-state laser. The linearly polarized laser light is incident on a polarizing beam splitter via a half-wave plate. The polarizing beam splitter splits the laser light into two light beams. The two light beams split by the polarizing beam splitter are combined by a second polarizing beam splitter.

Patent No. 6706155

In such a laser irradiation device, it is desirable to irradiate laser light suitable for the annealing process.

Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

According to one embodiment, the laser annealing device includes a laser light source that generates randomly polarized laser light, a polarizing beam splitter that splits the randomly polarized laser light, a polarization control element that controls the polarization state of the multiple laser lights split by the polarizing beam splitter, and a synthesis unit that synthesizes the multiple laser lights from the polarization control element and irradiates the target object.

According to one embodiment, the laser annealing method includes the steps of (a) generating randomly polarized laser light, (b) splitting the randomly polarized laser light with a polarizing beam splitter, (c) controlling the polarization states of the multiple laser lights split by the polarizing beam splitter, and (d) synthesizing the multiple laser lights with controlled polarization states and irradiating the target object.

According to one embodiment, a method for manufacturing a semiconductor device includes the steps of (S1) forming an amorphous film on a substrate, and (S2) annealing the amorphous film to crystallize the amorphous film to form a crystallized film, and the annealing step (S2) includes the steps of (A) generating randomly polarized laser light, (B) splitting the randomly polarized laser light with a polarizing beam splitter, (C) controlling the polarization state of the multiple laser lights split by the polarizing beam splitter, and (D) synthesizing the multiple laser lights with controlled polarization states and irradiating the target object.

According to the embodiment, it is possible to irradiate laser light suitable for the annealing process.

FIG. 2 is a diagram showing an optical system of the laser annealing apparatus according to the present embodiment. FIG. 1 is a block diagram showing a configuration of a laser annealing apparatus. FIG. 2 is a diagram showing an optical system of a laser annealing apparatus. FIG. 13 is a diagram showing an optical system of a laser annealing apparatus according to a modified example; 1 is a cross-sectional view showing a simplified configuration of an organic EL display. 1A to 1C are cross-sectional views showing steps of a manufacturing method of a semiconductor device according to an embodiment of the present invention. 1A to 1C are cross-sectional views showing steps of a manufacturing method of a semiconductor device according to an embodiment of the present invention. 1A to 1C are cross-sectional views showing steps of a manufacturing method of a semiconductor device according to an embodiment of the present invention. 1A to 1C are cross-sectional views showing steps of a manufacturing method of a semiconductor device according to an embodiment of the present invention. 1A to 1C are cross-sectional views showing steps of a manufacturing method of a semiconductor device according to an embodiment of the present invention. 1A to 1C are cross-sectional views showing steps of a manufacturing method of a semiconductor device according to an embodiment of the present invention. 1A to 1C are cross-sectional views showing steps of a manufacturing method of a semiconductor device according to an embodiment of the present invention. 1A to 1C are cross-sectional views showing steps of a manufacturing method of a semiconductor device according to an embodiment of the present invention.

Embodiment 1.
The laser annealing apparatus according to the present embodiment is, for example, an excimer laser annealing (ELA) apparatus for forming a low temperature polysilicon (LTPS) film. Hereinafter, the laser annealing apparatus, the laser annealing method, and the manufacturing method according to the present embodiment will be described with reference to the drawings.

(Optical system of ELA device)
The configuration of the ELA device 1 according to the present embodiment will be described with reference to FIG. 1. FIG. 1 is a diagram showing a schematic diagram of an optical system of the ELA device 1. A silicon film 101 is formed on the upper surface (main surface) of a substrate 100. The ELA device 1 irradiates a laser beam L1 onto the silicon film 101 formed on the substrate 100. This makes it possible to convert the amorphous silicon film (amorphous silicon film: a-Si film) 101 into a polycrystalline silicon film (polysilicon film: p-Si film) 101. The substrate 100 is, for example, a transparent substrate such as a glass substrate. The substrate 100 is an object to be irradiated with the laser beam.

In order to clarify the explanation, an XYZ three-dimensional orthogonal coordinate system is shown in FIG. 1. The Z direction is the vertical direction, which is perpendicular to the substrate 100. The XY plane is a plane parallel to the surface of the substrate 100 on which the silicon film 101 is formed. The X direction is the longitudinal direction of the rectangular substrate 100, and the Y direction is the lateral direction of the substrate 100. In the ELA device 1, the silicon film 101 is irradiated with laser light L1 while the substrate 100 is transported in the +X direction by a transport mechanism (not shown). In FIG. 1, the silicon film 101 before irradiation with the laser light L1 is shown as an amorphous silicon film 101a, and the silicon film 101 after irradiation with the laser light L1 is shown as a polysilicon film 101b.

The ELA device 1 includes a stage 10, a laser light source 21, an optical system 20, and a detection unit 22. The substrate 100 is placed on the stage 10. The stage 10 is, for example, a floating transport stage (floating transport unit) that floats the substrate 100 in the air, but is not limited to a floating transport stage. For example, the stage 10 may be a vacuum chuck type stage. The stage 10 ejects gas from below toward the substrate 100. Thus, the substrate 100 is transported in the +X direction with a small air gap formed between the stage 10 and the substrate 100.

The optical system 20 is an optical system for irradiating the silicon film 101 with laser light L1 for crystallizing the amorphous silicon film 101a. The optical system 20 includes a polarization control unit 30 that controls the polarization state of the laser light L1. The polarization control unit 30 controls the polarization state of the laser light L1. The detailed configuration of the optical system 20 will be described later.

The optical system 20 is disposed on the upper side (+Z side) of the substrate 100. The laser light source 21 is a pulsed laser light source that generates pulsed laser light. The laser light source 21 is, for example, an excimer laser light source that emits excimer laser light with a central wavelength of 308 nm. The laser light source 21 also emits pulsed laser light L1.

The optical system 20 includes a homogenizer for homogenizing the laser light L1, and a condenser lens for focusing the laser light L1. The laser light L1 forms a linear irradiation area on the substrate 100. The irradiation area is linear with the Y direction as the long side and the X direction as the short side.

The optical system 20 guides the laser light L1 from the laser light source 21 to the substrate 100. The laser light irradiated from the optical system 20 to the substrate 100 is referred to as laser light L2. The amorphous silicon film 101a is crystallized by the irradiation of the laser light L2. The silicon film 101 is irradiated with the laser light L2 while changing the irradiation position of the laser light L2 on the substrate 100. A uniform polysilicon film 101b is formed on the substrate 100 by transporting the substrate 100 in the +X direction using the transport mechanism of the stage 10. Of course, instead of a configuration in which the substrate 100 is transported, the laser light source 21 and the optical system 20 may be moved. In other words, it is sufficient that the irradiation area of the laser light L2 is scanned by moving the substrate 100 and the optical system 20 relatively.

Furthermore, a detection unit 22 is disposed on the substrate 100. The detection unit 22 includes a photodetector that detects light from the crystallized polysilicon film 101b. For example, the detection unit 22 includes a camera that captures the polysilicon film 101b. Alternatively, the detection unit 22 may include a spectrometer that measures the spectrum of the reflected light reflected by the polysilicon film 101b. Furthermore, the detection unit 22 may include an illumination light source that illuminates the substrate 100. For example, the illumination light source generates illumination light for illuminating the area irradiated with the laser light L2. The camera detects the reflected light from the area illuminated with the illumination light. Since the detection unit 22 can capture the area irradiated with the laser light L2, it is possible to evaluate the crystalline state of the polysilicon film 101b. It becomes possible to evaluate the uniformity and unevenness of the crystalline state of the polysilicon film 101b.

Figure 2 is a block diagram showing the configuration of the ELA device 1. The ELA device 1 includes a stage 10, an optical system 20, a laser light source 21, a detection unit 22, a system control unit 50, and a chamber 120. The optical system 20, the laser light source 21, and the detection unit 22 are the same as those shown in Figure 1, so detailed explanations will be omitted.

The chamber 120 is a process chamber that houses the stage 10 and the substrate 100. That is, the stage 10 is disposed within the chamber 120, and the substrate 100 is disposed on the stage 10. The laser annealing process is carried out within the chamber 120.

The system control unit 50 controls the operation of the stage 10, the laser light source 21, the optical system 20, and the polarization control unit 30. The system control unit 50 moves the stage 10 in the X direction. Furthermore, the system control unit 50 controls the output power of the laser light source 21, etc. Also, it controls the operation of the polarization control unit 30. This controls the polarization state of the laser light L2 irradiated to the substrate 100.

The system control unit 50 receives the detection results from the detection unit 22. The system control unit 50 then controls the laser light source 21 and the polarization control unit 30 in accordance with the detection results from the detection unit 22. In other words, the system control unit 50 controls the output power and polarization state of the laser light so that the crystal state of the polysilicon film 101b becomes more uniform.

Figure 3 is a diagram showing the configuration of the optical system 20 including the polarization control unit 30. The optical system 20 includes the polarization control unit 30 and a synthesis unit 60. The synthesis unit 60 includes a homogenizer 61 and a condenser lens 62.

First, the polarization control unit 30 will be described. The polarization control unit 30 includes a polarizing beam splitter 31, a mirror 32, a half-wave plate 33, a quarter-wave plate 34, and a quarter-wave plate 35. Furthermore, the polarization control unit 30 includes a polarizing beam splitter 41, a mirror 42, a half-wave plate 43, a quarter-wave plate 44, and a quarter-wave plate 45.

Figure 3 shows an example in which the laser light source 21 generates two laser beams L30 and laser beam L40. Specifically, a first laser light source 21a and a second laser light source 21b are provided. The first laser light source 21a generates laser beam L30. The second laser light source 21b generates laser beam L40. Note that laser beam from one laser light source may be split by a half mirror or the like. Of course, the number of laser light sources and the number of laser beams are not particularly limited. The laser beam L30 and the laser beam L40 are randomly polarized.

The laser light L30 emitted from the first laser light source 21a enters the polarizing beam splitter 31. The polarizing beam splitter 31 splits the laser light L30 into two laser lights L31 and L32. The polarizing beam splitter 31 splits the incident light according to the polarization state. Specifically, the polarizing beam splitter 31 transmits the P-polarized component and reflects the S-polarized component. Therefore, the laser light L31 that passes through the polarizing beam splitter 31 becomes linearly polarized P-polarized light. The laser light L32 that is reflected by the polarizing beam splitter 31 becomes linearly polarized S-polarized light.

The laser light L31 transmitted through the polarizing beam splitter 31 is incident on the quarter-wave plate 34. The quarter-wave plate 34 is rotatably disposed in the optical path of the laser light L31. Specifically, the quarter-wave plate 34 rotates around the optical axis of the laser light L31 as the axis of rotation. The laser light L31 transmitted through the quarter-wave plate 34 is incident on the homogenizer 61.

The laser light L32 reflected by the polarizing beam splitter 31 enters the half-wave plate 33. The optical axis of the half-wave plate 33 is inclined at 45° to the polarization direction of the laser light L32. Therefore, when the laser light L32 passes through the half-wave plate 33, the direction of linear polarization rotates 90°. Therefore, the laser light L33 that passes through the half-wave plate 33 becomes linearly polarized P-polarized light. By rotating the half-wave plate 33, the laser light L33 can be linearly polarized in any direction between P-polarized light and S-polarized light. The laser light L33 that passes through the half-wave plate 33 enters the quarter-wave plate 35. The quarter-wave plate 35 is rotatably arranged in the optical path of the laser light L33. Specifically, the quarter-wave plate 35 rotates around the optical axis of the laser light L33 as the rotation axis. The laser light L33 that passes through the quarter-wave plate 34 enters the homogenizer 61.

In the polarization control unit 30, the path of the laser light L40 is the same as the path of the laser light L30. That is, the polarizing beam splitter 41, the mirror 42, the half-wave plate 43, the quarter-wave plate 44, and the quarter-wave plate 45 correspond to the polarizing beam splitter 31, the mirror 32, the half-wave plate 33, the quarter-wave plate 34, and the quarter-wave plate 35, respectively.

The laser light L40 emitted from the second laser light source 21b is incident on the polarizing beam splitter 41. The polarizing beam splitter 41 splits the laser light L40 into two laser lights L41 and L42. The polarizing beam splitter 41 splits the incident light according to the polarization state. Specifically, the polarizing beam splitter 41 transmits the P-polarized component and reflects the S-polarized component. Therefore, the laser light L41 that passes through the polarizing beam splitter 41 becomes linearly polarized P-polarized light. The laser light L42 that is reflected by the polarizing beam splitter 41 becomes linearly polarized S-polarized light.

The laser light L41 that has passed through the polarizing beam splitter 41 is incident on the quarter-wave plate 44. The quarter-wave plate 44 is rotatably disposed in the optical path of the laser light L41. Specifically, the quarter-wave plate 44 rotates around the optical axis of the laser light L41 as the axis of rotation. The laser light L41 that has passed through the quarter-wave plate 44 is incident on the homogenizer 61.

The laser light L42 reflected by the polarizing beam splitter 41 enters the half-wave plate 43. The optical axis of the half-wave plate 43 is inclined by 45° to the polarization direction of the laser light L42. Therefore, when the laser light L42 passes through the half-wave plate 43, the direction of linear polarization rotates by 90°. Therefore, the laser light L43 that passes through the half-wave plate 43 becomes linearly polarized P-polarized light. By rotating the half-wave plate 43, the laser light L43 can be linearly polarized in any direction between P-polarized light and S-polarized light. The laser light L42 that passes through the half-wave plate 43 enters the quarter-wave plate 45. The quarter-wave plate 45 is rotatably arranged in the optical path of the laser light L43. Specifically, the quarter-wave plate 45 rotates around the optical axis of the laser light L42 as the rotation axis. The laser light L43 that passes through the quarter-wave plate 44 enters the homogenizer 61.

As described above, the quarter-wave plates 34, 35, 44, and 45 are arranged to be rotatable. For example, when the optical axis of the quarter-wave plate 34 is inclined by 45° to the polarization direction of the laser light L31, the laser light L31 becomes circularly polarized. Furthermore, when the optical axis of the quarter-wave plate 34 is deviated from the polarization direction of the laser light L31 by 45°, the laser light L31 becomes elliptically polarized. Then, by changing the angle of the quarter-wave plate 34, the angle and degree of the ellipse can be adjusted. Similarly, by changing the rotation angles of the quarter-wave plates 34, 35, 44, and 45, respectively, the polarization states of the laser lights L33, L41, and L43 can be adjusted. In this way, the quarter-wave plates 34, 35, 44, and 45 each function as a polarization control element.

Next, the combining unit 60 will be described. The laser beams L31, L33, L41, and L43 are incident on the homogenizer 61. The homogenizer 61 combines the laser beams L31, L33, L41, and L43 to form a line-shaped light beam. The homogenizer 61 has, for example, a lens array in which a plurality of lenses are arranged in an array. For example, each of the laser beams L31, L33, L41, and L43 is incident on a plurality of lenses to form a plurality of light beams.

The laser light L2 combined by the homogenizer 61 is collected by the condenser lens 62 and irradiated onto the substrate 100. On the substrate 100, the laser light L2 is a line beam with the Y direction as the longitudinal direction and the X direction as the transverse direction. The laser light L2 forms a linear irradiation area along the Y direction on the substrate 100. Furthermore, the laser light L2 has a flat-top light intensity distribution.

As described above, the quarter-wave plates 34, 35, 44, and 45 are arranged to be rotatable. Therefore, the system control unit 50 can adjust the polarization state of the laser light by rotating the quarter-wave plates 34, 35, 44, and 45.

In this way, the substrate 100 can be irradiated with laser light L2 in any polarization state. The polarization state can be controlled to obtain the optimal crystal arrangement depending on the irradiation conditions of the laser light L1 and the type of the substrate 100. Furthermore, by independently adjusting the rotation angles of the quarter-wave plates 34, 35, 44, and 45, each of the laser lights L31, L33, L41, and L43 can be made to have any polarization state. A line beam can be obtained by combining multiple optical axes with any polarization state. This allows the polarization state to be controlled with a high degree of freedom, making it possible to irradiate laser light suitable for the annealing process.

For example, in FIG. 3, P-polarized laser beams L31, L33, L41, and L43 are incident on quarter-wave plates 34, 35, 44, and 45, respectively. For example, by making the angles between the polarization directions of laser beams L31, L33, L41, and L43 and the optical axes of quarter-wave plates 34, 35, 44, and 45 the same angle, laser beams L31, L33, L41, and L43 can be in the same polarization state. Then, the combining unit 60 can combine laser beams L31, L33, L41, and L43 in the same polarization state.

Alternatively, the angles between the polarization directions of the laser beams L31, L33, L41, and L43 and the optical axes of the quarter-wave plates 34, 35, 44, and 45 can be different, so that the laser beams L31, L33, L41, and L43 can be in different polarization states. Then, in the combining unit 60, the laser beams L31, L33, L41, and L43 in different polarization states are combined and irradiated onto the substrate 100. This allows the polarization state to be controlled with a high degree of freedom, making it possible to irradiate laser beams suitable for the annealing process.

In this way, the quarter-wave plate 34 and the quarter-wave plate 35 are arranged in the optical paths of the two laser beams L31 and L32 split by the polarizing beam splitter 31. The rotatably arranged quarter-wave plate 34 and the quarter-wave plate 35 function as polarization control elements. In other words, by rotating the quarter-wave plate 34 and the quarter-wave plate 35, respectively, the polarization state of each of the two laser beams L31 and L33 can be adjusted independently.

Similarly, a quarter-wave plate 44 and a quarter-wave plate 45 are disposed in the optical paths of the two laser beams L41 and L42 split by the polarizing beam splitter 41. The quarter-wave plate 44 and the quarter-wave plate 45 function as polarization control elements by rotating them. In other words, by rotating the quarter-wave plate 44 and the quarter-wave plate 45, respectively, the polarization state of each of the two laser beams L41 and L43 can be adjusted independently. Note that the polarization control element is not limited to a wave plate such as a half-wave plate or a quarter-wave plate.

The combining unit 60 combines the laser beams L31, L33, L41, and L43 whose polarization states have been adjusted, and irradiates the substrate 100. This allows the polarization state of the laser beam L2 irradiated to the substrate 100 to be controlled with a high degree of freedom.

The system control unit 50 may control the polarization state according to the evaluation result of the crystalline state of the polysilicon film 101b. For example, the detection unit 22 detects the crystalline state of the polysilicon film 101b. According to the detection result of the detection unit 22, the system control unit 50 adjusts the rotation angles of the 1/4 wavelength plate 34, the 1/4 wavelength plate 35, the 1/4 wavelength plate 44, and the 1/4 wavelength plate 45. This makes it possible to generate a polarization state suitable for various process conditions. For example, the polarization state can be optimized according to the output power of the laser light, the type of the substrate 100, the thickness of the silicon film 101, the transport speed of the substrate 100, etc. For example, the system control unit 50 controls the polarization state so that the variation in the crystalline state of the polysilicon film 101b is reduced. This makes it possible to irradiate the laser light L2 in a polarization state suitable for the annealing process.

In FIG. 3, the combining unit 60 combines four laser beams L31, L33, L41, and L43, but the number of laser beams combined by the combining unit 60 is not particularly limited. In other words, the combining unit 60 may combine two or more laser beams.

In the above description, the quarter-wave plates 34, 35, 44, and 45 are used as the polarization control elements, but the half-wave plates 33 and 43 may be used as the polarization control elements. For example, the polarization state can be controlled by rotating the half-wave plates 33 and 43 around the optical axis. In this case, as shown in FIG. 4, the half-wave plates 33, 37, 43, and 47 may be disposed in all the optical paths of the laser beams L31, L33, L41, and L43. In FIG. 4, the half-wave plate 37 is added to the optical path of the laser beam L31, and the half-wave plate 47 is added to the optical path of the laser beam L41. In addition, the polarization state of part of the laser beams L31, L33, L41, and L43 may be controlled by the quarter-wave plate, and the polarization state of the rest may be controlled by the half-wave plate.

By using the polarizing beam splitters 31 and 41, the randomly polarized laser light is split almost evenly. Then, by controlling the polarization state of the two split laser lights, the laser light L2 can be easily brought into the desired polarization state. Furthermore, the laser light can be used efficiently. In other words, since no polarizers or the like are used, absorption of the laser light can be prevented, and the laser light can be used efficiently.

The laser annealing method according to this embodiment includes the steps of generating randomly polarized laser light, splitting the randomly polarized laser light with a polarizing beam splitter, controlling the polarization state of the multiple laser lights split by the polarizing beam splitter, and combining the multiple laser lights with controlled polarization states to irradiate an object. This allows the polarization state to be controlled with a high degree of freedom, making it possible to irradiate a laser light suitable for the annealing process.

The polarization state of the laser light affects the grain size and orientation of the crystals. In this embodiment, the laser light can be controlled to have any polarization state. Therefore, the polarization state can be controlled to improve the quality of the crystals, such as uniformity, periodicity, and orientation. Controlling the microscopic crystal state makes it possible to adjust under conditions where unevenness is less likely to occur.

It is also preferable to use a floating transport stage as the stage 10, which transports the substrate 100 while floating it. In particular, a floating transport stage is excellent for transporting large substrates. When performing ELA processing on large substrates, it is necessary to reduce the ELA cost per unit product price. When annealing a large substrate using a floating transport stage, appropriate annealing is possible by converting the randomly polarized excimer laser into polarized light before irradiating it. Furthermore, by controlling the polarization state based on the evaluation results of the crystal state in the detection unit 22, it is possible to obtain high-quality crystals with high productivity.

(Organic EL display)
The semiconductor device having the polysilicon film is suitable for a TFT (Thin Film Transistor) array substrate for an organic EL (ElectroLuminescence) display. That is, the polysilicon film is used as a semiconductor layer having a source region, a channel region, and a drain region of the TFT.

The following describes a configuration in which the semiconductor device according to this embodiment is applied to an organic EL display. FIG. 5 is a cross-sectional view showing a simplified pixel circuit of an organic EL display. The organic EL display 300 shown in FIG. 5 is an active matrix display device in which a TFT is arranged in each pixel PX.

The organic EL display 300 includes a substrate 310, a TFT layer 311, an organic layer 312, a color filter layer 313, and a sealing substrate 314. FIG. 5 shows a top-emission organic EL display in which the sealing substrate 314 side is the viewing side. Note that the following description shows one configuration example of an organic EL display, and the present embodiment is not limited to the configuration described below. For example, the semiconductor device according to the present embodiment may be used in a bottom-emission organic EL display.

The substrate 310 is a glass substrate or a metal substrate. A TFT layer 311 is provided on the substrate 310. The TFT layer 311 has a TFT 311a arranged in each pixel PX. Furthermore, the TFT layer 311 has wiring (not shown) connected to the TFT 311a, etc. The TFT 311a and the wiring etc. constitute a pixel circuit.

An organic layer 312 is provided on the TFT layer 311. The organic layer 312 has an organic EL light-emitting element 312a arranged for each pixel PX. The organic EL light-emitting element 312a has a layered structure in which, for example, an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode are layered. In the case of the top emission type, the anode is a metal electrode, and the cathode is a transparent conductive film such as ITO (Indium Tin Oxide). Furthermore, the organic layer 312 is provided with partitions 312b for separating the organic EL light-emitting elements 312a between the pixels PX.

A color filter layer 313 is provided on the organic layer 312. The color filter layer 313 is provided with a color filter 313a for color display. That is, a resin layer colored R (red), G (green), or B (blue) is provided as the color filter 313a in each pixel PX. When the white light emitted from the organic layer 312 passes through the color filter 313a, it is converted into light of the colors RGB. In the case of a three-color method in which the organic layer 312 is provided with organic EL light-emitting elements that emit each of the colors RGB, the color filter layer 313 may be omitted.

A sealing substrate 314 is provided on the color filter layer 313. The sealing substrate 314 is a transparent substrate such as a glass substrate, and is provided to prevent deterioration of the organic EL light-emitting elements of the organic layer 312.

The current flowing through the organic EL element 312a of the organic layer 312 varies depending on the display signal supplied to the pixel circuit. Therefore, by supplying a display signal corresponding to the display image to each pixel PX, the amount of light emitted by each pixel PX can be controlled. This allows the desired image to be displayed.

In an active matrix display device such as an organic EL display, one pixel PX is provided with one or more TFTs (e.g., switching TFTs or driving TFTs). The TFT of each pixel PX is provided with a semiconductor layer having a source region, a channel region, and a drain region. The polysilicon film according to this embodiment is suitable for the semiconductor layer of a TFT. In other words, by using the polysilicon film manufactured by the above manufacturing method as the semiconductor layer of a TFT array substrate, it is possible to suppress in-plane variations in TFT characteristics. Therefore, a display device with excellent display characteristics can be manufactured with high productivity.

(Method of manufacturing a semiconductor device)
The method for manufacturing a semiconductor device using the ELA apparatus according to the present embodiment is suitable for manufacturing a TFT array substrate. The method for manufacturing a semiconductor device having TFTs will be described with reference to Figs. 6 to 13. Figs. 6 to 13 are cross-sectional views showing the manufacturing process of a semiconductor device. In the following description, a method for manufacturing a semiconductor device having inverted staggered type TFTs will be described.

First, as shown in FIG. 6, a gate electrode 402 is formed on a glass substrate 401. The glass substrate 401 corresponds to the substrate 100 described above. The gate electrode 402 can be, for example, a metal thin film containing aluminum or the like. A metal thin film is formed on the glass substrate 401 by sputtering or vapor deposition. The metal thin film is then patterned by photolithography to form the gate electrode 402. In the photolithography method, processes such as resist coating, exposure, development, etching, and resist peeling are performed. Various wirings, etc. may be formed in the same process as the patterning of the gate electrode 402.

Next, as shown in FIG. 7, a gate insulating film 403 is formed on the gate electrode 402. The gate insulating film 403 is formed so as to cover the gate electrode 402. Then, as shown in FIG. 8, an amorphous silicon film 404 is formed on the gate insulating film 403. The amorphous silicon film 404 is disposed so as to overlap the gate electrode 402 via the gate insulating film 403.

The gate insulating film 403 is a silicon nitride film (SiN _x ), a silicon oxide film (SiO ₂ film), or a laminated film of these, etc. Specifically, the gate insulating film 403 and the amorphous silicon film 404 are continuously formed by a CVD (Chemical Vapor Deposition) method.

Then, the amorphous silicon film 404 is irradiated with laser light L1 to form a polysilicon film 405 as shown in FIG. 9. That is, the amorphous silicon film 404 is crystallized by the ELA device 1 shown in FIG. 1, etc. As a result, a polysilicon film 405 made of crystallized silicon is formed on the gate insulating film 403. The polysilicon film 405 corresponds to the polysilicon film 101b described above.

At this time, the polysilicon film 405 is inspected by the inspection method according to the present embodiment. If the polysilicon film 405 does not satisfy the predetermined criteria, the polysilicon film 405 is irradiated with laser light again. This makes it possible to make the characteristics of the polysilicon film 405 more uniform. Since the variation within the surface can be suppressed, a display device with excellent display characteristics can be manufactured with high productivity.

Although not shown in the figure, the polysilicon film 405 is patterned by photolithography. Impurities may also be introduced into the polysilicon film 405 by ion implantation or the like.

After that, as shown in FIG. 10, an interlayer insulating film 406 is formed on the polysilicon film 405. The interlayer insulating film 406 has a contact hole 406a for exposing the polysilicon film 405.

The interlayer insulating film 406 is a silicon nitride film (SiN _x ), a silicon oxide film (SiO ₂ film), or a laminated film of these. Specifically, the interlayer insulating film 406 is formed by a CVD method. Then, the interlayer insulating film 406 is patterned by a photolithography method to form a contact hole 406a.

Next, as shown in FIG. 11, a source electrode 407a and a drain electrode 407b are formed on the interlayer insulating film 406. The source electrode 407a and the drain electrode 407b are formed so as to cover the contact hole 406a. That is, the source electrode 407a and the drain electrode 407b are formed from within the contact hole 406a to the top of the interlayer insulating film 406. Therefore, the source electrode 407a and the drain electrode 407b are electrically connected to the polysilicon film 405 via the contact hole 406a.

This forms the TFT 410. The TFT 410 corresponds to the TFT 311a described above. In the polysilicon film 405, the region that overlaps with the gate electrode 402 becomes the channel region 405c. In the polysilicon film 405, the side of the source electrode 407a from the channel region 405c becomes the source region 405a, and the side of the drain electrode 407b becomes the drain region 405b.

The source electrode 407a and the drain electrode 407b are formed from a metal thin film containing aluminum or the like. A metal thin film is formed on the interlayer insulating film 406 by sputtering or vapor deposition. The metal thin film is then patterned by photolithography to form the source electrode 407a and the drain electrode 407b. Note that various wirings may be formed in the same process as the patterning of the source electrode 407a and the drain electrode 407b.

Then, as shown in FIG. 12, a planarization film 408 is formed on the source electrode 407a and the drain electrode 407b. The planarization film 408 is formed so as to cover the source electrode 407a and the drain electrode 407b. Furthermore, the planarization film 408 is provided with a contact hole 408a for exposing the drain electrode 407b.

The planarization film 408 is formed, for example, from a photosensitive resin film. A photosensitive resin film is applied onto the source electrode 407a and the drain electrode 407b, and is then exposed and developed. This allows the planarization film 408 to be patterned with contact holes 408a.

Then, as shown in FIG. 13, a pixel electrode 409 is formed on the planarization film 408. The pixel electrode 409 is formed so as to cover the contact hole 408a. That is, the pixel electrode 409 is formed from within the contact hole 408a to the top of the planarization film 408. Therefore, the pixel electrode 409 is electrically connected to the drain electrode 407b via the contact hole 408a.

The pixel electrode 409 is formed of a transparent conductive film or a metal thin film containing aluminum or the like. A conductive film (transparent conductive film or metal thin film) is formed on the planarization film 408 by sputtering or the like. Then, the conductive film is patterned by photolithography. As a result, the pixel electrode 409 is formed on the planarization film 408. In the case of a driving TFT of an organic EL display, an organic EL light-emitting element 312a, a color filter (CF) 313a, etc., as shown in FIG. 5, are formed on the pixel electrode 409. In the case of a top-emission organic EL display, the pixel electrode 409 is formed of a metal thin film containing aluminum or silver, which has a high reflectivity. In the case of a bottom-emission organic EL display, the pixel electrode 409 is formed of a transparent conductive film such as ITO.

The manufacturing process for inverted staggered TFTs has been described above, but the manufacturing method according to this embodiment may also be applied to the manufacture of inverted staggered TFTs. Of course, the manufacturing method for TFTs is not limited to the manufacture of TFTs for organic EL displays, but can also be applied to the manufacture of TFTs for LCDs (Liquid Crystal Displays).

In the above description, the laser annealing apparatus according to the present embodiment has been described as irradiating an amorphous silicon film with laser light to form a polysilicon film, but it may also be irradiating an amorphous silicon film with laser light to form a microcrystalline silicon film. Furthermore, the laser light used for annealing is not limited to an excimer laser. The method according to the present embodiment can also be applied to a laser annealing apparatus that crystallizes a thin film other than a silicon film. In other words, the method according to the present embodiment can be applied to any laser annealing apparatus that irradiates an amorphous film with laser light to form a crystallized film. The laser annealing apparatus according to the present embodiment can appropriately modify a substrate with a crystallized film.

The present invention is not limited to the above embodiment, and can be modified as appropriate without departing from the spirit and scope of the invention.

REFERENCE SIGNS LIST 1 ELA device 10 Stage 20 Optical system 21 Laser light source 21a First laser light source 21b Second laser light source 22 Detection unit 30 Polarization control unit 31 Polarizing beam splitter 32 Mirror 33 1/2 wavelength plate 34 1/4 wavelength plate 35 1/4 wavelength plate 37 1/2 wavelength plate 41 Polarizing beam splitter 42 Mirror 43 1/2 wavelength plate 44 1/4 wavelength plate 45 1/4 wavelength plate 47 1/2 wavelength plate 50 System control unit 60 Synthesis unit 61 Homogenizer 62 Condenser lens 100 Substrate 101 Silicon film 101a Amorphous silicon film 101b Polysilicon film 120 Chamber 300 Organic EL display 310 Substrate 311 TFT layer 311a TFT
312 organic layer 312a organic EL light emitting element 312b partition wall 313 color filter layer 313a color filter (CF)
314 Sealing substrate 401 Glass substrate 402 Gate electrode 403 Gate insulating film 404 Amorphous silicon film 405 Polysilicon film 406 Interlayer insulating film 407a Source electrode 407b Drain electrode 408 Planarization film 409 Pixel electrode 410 TFT
PX Pixel

Claims (17)

A laser light source that generates randomly polarized laser light;
a polarizing beam splitter that splits the randomly polarized laser light;
a polarization control element for controlling the polarization states of the plurality of laser beams split by the polarizing beam splitter;
a synthesis unit that synthesizes the plurality of laser beams from the polarization control element and irradiates the laser beam onto an object ,
The polarization control element is
a quarter-wave plate disposed in each of the optical paths of the two laser beams split by the polarizing beam splitter;
A laser annealing apparatus that controls the polarization state of laser light by rotating the quarter-wave plate . The polarization control element is
a half-wave plate disposed in an optical path of at least one of the two laser beams split by the polarizing beam splitter;
2. The laser annealing apparatus according to claim 1, wherein the polarization state of the laser light is controlled by rotating the half-wave plate . An amorphous film is formed on the object,
3. The laser annealing apparatus according to claim 1, wherein the film is crystallized by the laser light. A laser light source that generates randomly polarized laser light;
a polarizing beam splitter that splits the randomly polarized laser light;
a polarization control element for controlling the polarization states of the plurality of laser beams split by the polarizing beam splitter;
a synthesis unit that synthesizes the plurality of laser beams from the polarization control element and irradiates the laser beam onto an object,
An amorphous film is formed on the object,
The film is crystallized by the laser light,
A detection unit for evaluating the crystal state of the crystallized film is further provided,
A laser annealing apparatus in which the polarization state is controlled in accordance with the evaluation result in the detection unit. The laser light combined by the combining unit forms a linear irradiation area along a first direction on the object,
5. The laser annealing apparatus according to claim 1, wherein the object is irradiated with the laser light while being moved along a second direction intersecting the first direction in a top view. The laser annealing device according to any one of claims 1 to 5, further comprising a levitation transport stage that transports the object while levitating it. (a) generating randomly polarized laser light;
(b) splitting the randomly polarized laser light with a polarizing beam splitter;
(c) controlling the polarization states of the plurality of laser beams split by the polarizing beam splitter;
(d) combining the plurality of laser beams whose polarization states have been controlled and irradiating the combined laser beams onto an object;
a quarter-wave plate is disposed in each of the optical paths of the two laser beams split by the polarizing beam splitter;
A laser annealing method in which the polarization state of the laser light is controlled by rotating the quarter-wave plate . a half-wave plate is disposed in the optical path of at least one of the two laser beams split by the polarizing beam splitter;
8. The laser annealing method according to claim 7, wherein the polarization state of the laser light is controlled by rotating the half-wave plate . An amorphous film is formed on the object,
9. The laser annealing method according to claim 7, wherein the film is crystallized by the laser light. (a) generating randomly polarized laser light;
(b) splitting the randomly polarized laser light with a polarizing beam splitter;
(c) controlling the polarization states of the plurality of laser beams split by the polarizing beam splitter;
(d) combining the plurality of laser beams whose polarization states have been controlled and irradiating the combined laser beams onto an object;
An amorphous film is formed on the object,
The film is crystallized by the laser light,
Evaluating the crystal state of the crystallized film;
A laser annealing method for controlling the polarization state in accordance with a result of evaluation of the crystal state. The combined laser light forms a linear irradiation area along a first direction on the object,
11. The laser annealing method according to claim 7, wherein the object is irradiated with the laser light while being moved along a second direction intersecting the first direction in a top view. In the step (d),
12. The laser annealing method according to claim 7, wherein the object is transported while being levitated using a levitation transport stage. (S1) forming an amorphous film on a substrate;
(S2) annealing the amorphous film to crystallize the amorphous film to form a crystallized film;
The annealing step (S2) includes:
(A) generating randomly polarized laser light;
(B) splitting the randomly polarized laser light with a polarizing beam splitter;
(C) controlling the polarization states of the plurality of laser beams split by the polarizing beam splitter;
(D) combining the plurality of laser beams whose polarization states have been controlled, and irradiating the combined laser beams onto an object;
a quarter-wave plate is disposed in each of the optical paths of the two laser beams split by the polarizing beam splitter;
A method for manufacturing a semiconductor device , comprising: rotating the quarter-wave plate to control the polarization state of the laser light . a half-wave plate is disposed in an optical path of at least one of the two laser beams split by the polarizing beam splitter;
The method for manufacturing a semiconductor device according to claim 13, wherein the polarization state of the laser light is controlled by rotating the half-wave plate . (S1) forming an amorphous film on a substrate;
(S2) annealing the amorphous film to crystallize the amorphous film to form a crystallized film;
The annealing step (S2) includes:
(A) generating randomly polarized laser light;
(B) splitting the randomly polarized laser light with a polarizing beam splitter;
(C) controlling the polarization states of the plurality of laser beams split by the polarizing beam splitter;
(D) combining the plurality of laser beams whose polarization states have been controlled, and irradiating the combined laser beams onto an object;
Evaluating the crystalline state of the crystallized film;
A method for manufacturing a semiconductor device, in which the polarization state is controlled in accordance with the evaluation result of the crystal state. The combined laser light forms a linear irradiation area along a first direction on the substrate,
16. The method for manufacturing a semiconductor device according to claim 13, wherein the laser light is irradiated while the substrate is moved along a second direction intersecting the first direction in a top view. In the step (D),
The method for manufacturing a semiconductor device according to any one of claims 13 to 16, wherein the substrate is transported while being floated using a floating transport stage.

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