JP2007324519A - Laser annealing device and method of manufacturing display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser annealing device adapted for preventing damage to a substrate adsorption base caused by the transmission of laser light incident to a glass substrate, and to provide a method of manufacturing a display device. <P>SOLUTION: A table protection film 80 for reflecting laser light 30 which is transmitted through a glass substrate 1 is arranged on a top table 1 which is movable mounted with the glass substrate 1. Further, a silicon film 63 on the surface of the glass substrate 1 is annealed by temporally modulating the energy of the laser light emitted by a laser light source of a laser annealing device, regulating the energy distribution of the energy-modulated laser light, scanning the laser light 30 which has the temporally modulated energy and the regulated energy distribution over the surface of the glass substrate 1 having a thin film formed on the surface, and irradiating the surface. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laser annealing apparatus suitable for improving film quality, expanding crystal grains, or making a single crystal by irradiating an amorphous or polycrystalline semiconductor film formed on an insulating substrate with a laser beam. The present invention relates to a method for manufacturing a display device.

  In recent years, liquid crystal display panels form images by switching thin film transistors formed of an amorphous or polycrystalline silicon film on a substrate such as glass or fused quartz. If it is possible to simultaneously form a driver circuit for driving a pixel transistor on this substrate, a drastic reduction in manufacturing cost and improvement in reliability can be expected.

  However, since a silicon film forming an active layer of a transistor has low crystallinity, the performance of a thin film transistor typified by mobility characteristics is low, and it is difficult to manufacture a circuit that requires high speed and high functionality. In order to manufacture these high-speed and high-functional circuits, a thin film transistor having a high mobility characteristic is required. In order to realize this, it is necessary to improve the crystallinity of the silicon thin film.

  Conventionally, excimer laser annealing has attracted attention as a technique for improving crystallinity. This method improves mobility characteristics by irradiating an excimer laser to an amorphous silicon film formed on an insulating substrate such as glass to change the amorphous silicon film to a polycrystalline silicon film. is there.

  However, the polycrystalline film obtained by excimer laser irradiation has a crystal grain size of about several hundreds of nanometers and is insufficient in performance to be applied to a driver circuit for driving a liquid crystal display panel.

  As a method for solving this problem, Japanese Patent Application Laid-Open No. H10-228688 has no influence due to interference of laser light oscillated from a laser oscillator, has an energy density distribution suitable for annealing at an irradiated portion, has an optimum pulse width, and is temporal. In addition, by irradiating a laser beam having an energy change suitable for annealing, crystal grains such as an amorphous or polycrystalline silicon thin film are grown in a desired direction, and a large number of crystal grains having a size exceeding about 10 μm are formed. A laser annealing apparatus and a laser annealing method that can be converted into a crystalline silicon thin film and can greatly improve the mobility characteristics of the polycrystalline silicon thin film are disclosed.

JP 2003-124136 A

  However, in the conventional laser annealing apparatus, the laser annealing apparatus can move the glass substrate 1 on which the passivation film 62 and the silicon film 63 are formed on the surface of the glass plate 61 as shown in the enlarged sectional view of the main part in FIG. When placed on the top table 2 and irradiated with laser light 30 from above the glass substrate 1 through the objective lens 22, about 90% or more of the energy of the laser light 30 is transmitted through the glass substrate 1, and the substrate adsorption base The laser beam 30 transmitted through the glass substrate 1 causes damage to the substrate adsorption base of the top table 2 such as temperature rise, deformation, and melting, thereby reducing reliability. In addition, a board | substrate adsorption | suction base here points out the surface part of the top table 2 with which the back surface of the glass substrate 1 contacts.

  Further, in the laser annealing apparatus configured as described above, the top table 2 needs to travel in the XY directions, needs high-precision processing, and needs to be low in cost. used.

  Further, the laser beam 30 condensed by the objective lens 22 is irradiated to the silicon film 63, and the silicon film 63 is melted and recrystallized. However, the rate at which the silicon film 63 absorbs the energy of the laser light 30 is about 10% or less, and most of the light passes through the glass substrate 1 and reaches the substrate adsorption base of the top table 2. Since the top table 2 is made of natural stone, the top table 2 is composed of various components. Therefore, the top table 2 includes a component that is weak against heat, a component having a high absorption rate, and the like.

  The laser light 30 that has reached the substrate adsorption base of the top table 2 is absorbed by a part of the components of the top table 2, and causes temperature rise on the surface of the top table 2, and further damage such as deformation and melting. As an improvement method, there is a method of transmitting the laser beam 30 by using quartz glass for the top table 2, but there is a vibration isolating plate under the top table 2, and this anti-vibration surface plate also needs to be formed of quartz glass. There is. The anti-vibration surface plate has a larger shape than the top table 2, and it is not practical to use quartz glass to increase the cost.

  Accordingly, the present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a laser annealing apparatus and a display in which damage to the substrate adsorption base of the top table due to transmission of laser light to the glass substrate is prevented. It is to provide a method for manufacturing an apparatus.

  In order to achieve such an object, the laser annealing apparatus according to the present invention is characterized in that a protective film having a low laser light absorption rate is provided on the sample adsorption surface base of the stage means.

  Further, another laser annealing apparatus according to the present invention is preferably characterized in that, in the above configuration, the protective film is an air film.

  Still another laser annealing apparatus according to the present invention is preferably characterized in that, in the above configuration, the protective film is a laser light reflecting film.

  The display device manufacturing method according to the present invention also includes a stage unit on which a sample can be placed and moved, a laser light source unit that generates laser light, and a projection that projects laser light emitted from the laser light source onto the surface of the sample. An annealing process for annealing a part on the substrate by a laser annealing apparatus comprising an optical system means and providing a protective film with a low laser light absorption rate on the sample adsorption surface base of the stage means, and an annealing process on the substrate And a step of forming a drive circuit in the region annealed by the above.

  It should be noted that the present invention is not limited to the configurations described in the above-described configurations and the embodiments described later, and it goes without saying that various modifications can be made without departing from the technical idea of the present invention. .

  According to the present invention, the sample adsorption base of the stage means is damaged by the laser irradiation of the sample by providing the sample adsorption surface base of the stage means with the protective film having a low absorption rate of the laser light transmitted through the sample. Therefore, it has an extremely excellent effect such as obtaining a highly reliable laser annealing apparatus.

  In addition, according to the method for manufacturing a display device according to the present invention, a laser beam whose energy distribution is adjusted while temporally modulating the energy of the laser beam emitted from the laser light source onto the surface of the sample by a highly reliable laser annealing device. By scanning and irradiating the semiconductor film, a semiconductor film having high mobility characteristics can be formed, so that an extremely excellent effect such as formation of a highly integrated circuit on the sample surface can be obtained.

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

  1A and 1B are diagrams for explaining the configuration of a laser annealing apparatus according to a first embodiment of the present invention. FIG. 1A is a plan view seen from above, and FIG. 1B is a plan view seen from the side. . In FIG. 1, a laser annealing apparatus is mounted with a glass substrate 1 as a sample adsorbed on a substrate adsorption base on a top table 2 as a stage means. Moreover, the XY stage 3 fixed on the surface plate 6 provided with the vibration isolator 5 is provided, and the glass substrate 1 can be moved by running the top table 2 in the XY directions. Reference numeral 4 denotes a frame for supporting and fixing the surface plate 6 on the XY stage 3. A laser optical system (not shown) is disposed on the surface plate 6.

  2A and 2B are diagrams showing the configuration of the laser optical system described in FIG. In FIG. 2, the laser optical system includes laser oscillators 10-1 to 10-4 that oscillate continuous-wave laser light, beam expanders 11-1 to 11-4 that expand the beam diameter of the laser light, and laser light on. EO (electro-optic) modulators 12-1 to 12-4 that perform temporal modulation as necessary / off, a prism 16 that collimates two beams, and a laser beam that is compressed in one direction. It comprises a DOE (diffractive optical element) 17 that converts it into a linear beam and an objective lens 22 that projects onto the glass substrate 1.

  In FIG. 2, 13-1 and 13-2 are mirrors, 14-1 and 14-2 are polarization beam splitters, 15-1 and 15-2 are mirrors, 18 is an imaging lens, 19 is a cylindrical lens, 20 Is a mirror and 21 is an imaging lens.

  FIG. 3 is a perspective view showing a state in which the glass substrate is irradiated with laser light. As shown in FIG. 3, the laser beam 30 shaped by the laser optical system of FIG. 2 is irradiated from above to below the glass substrate 1. The glass substrate 1 is moved from the right side to the left side indicated by arrows in the horizontal direction by the XY stage 3 shown in FIG. The laser beam 30 is on / off controlled by the EO modulators 12-1 to 12-4 shown in FIG. 2, and the molten recrystallized region 32 is formed by irradiating the laser beam 30 only at a necessary place.

  FIG. 4 is a plan view showing a laser irradiation region of the glass substrate 1 to which the present invention is applied. 33 shown by a broken line is a cutting position at the time of cutting in the manufacturing process of the display device described later after the melt recrystallization region 33 is formed.

  FIG. 5 is a plan view showing the positional relationship between the melt recrystallization region 32 and the region that becomes the display unit of the display device in the glass substrate 1. In the drawing, the display portion 51 is formed within the broken line, the melt recrystallization region 32 forms the display portion 51, and the melt recrystallization region 32 is formed in the peripheral portion of the display portion 51.

  FIG. 6 is an enlarged cross-sectional view of the glass substrate 1 before the melt recrystallization region 32 is formed. In the glass substrate 1, a passivation film 62 is formed on the surface of a glass plate 61, and a silicon film 63 is formed on the surface of the passivation film 62.

  FIG. 7 is an enlarged cross-sectional view showing a main part of the configuration of the top table 2 of the laser annealing apparatus according to the present invention. In FIG. 7, a table protective film 80 that reflects the laser beam 30 transmitted through the glass substrate 1 upward is formed on the substrate suction base (the surface of the top table 2) that contacts the back surface of the glass substrate 1 of the top table 2. It is deposited.

  Examples of the material applied to the table protective film 80 include white alumina, gray alumina, titania, zirconia, chromia, zircon magnesia spines, magnesia, tungsten carbide, titanium carbide, silicon carbide, chrome carbide, aluminum, A material film that does not transmit laser light, such as nickel, copper, nichrome, molybdenum, tungsten, or titanium, is preferable. Further, either an alloy material or a mixture containing these materials as a main component may be used.

  Moreover, as a method of forming the table protective film 80 on the substrate adsorption base of the top table 2, there is a spraying method in which the protective film material is melted and sprayed. Further, since the flatness of the surface of the protective film 80 on the top table 2 after spraying is lowered, the processing accuracy is increased by means such as polishing. The protective film 80 has a thickness of about 100 μm.

  In the laser annealing apparatus configured as described above, the laser light 30 collected by the objective lens 22 is irradiated onto the silicon film 63, and the silicon film 63 is melted and melted and recrystallized. The laser beam 30 transmitted through the silicon film 63 passes through the passivation film 62 and the glass plate 61 and reaches the table protection film 80. The laser beam 30 reaching the table protection film 80 is reflected upward by the table protection film 80 and reaches the glass plate 61, the passivation film 62 and the silicon film 63 again. The reflected laser beam 30 is not condensed and is in a scattered state, so that it does not affect the melt recrystallization.

  According to such a configuration, most of the energy of the laser beam 30 transmitted through the glass substrate 1 is reflected by the table protective film 80, so that damage such as temperature rise, deformation, and melting of the substrate adsorption base of the top table 2 is achieved. Can be prevented, so that reliability is improved.

  FIG. 8 is a plan view of an essential part showing a state where the glass substrate 1 is mounted on the top table 2 shown in FIG. In FIG. 8, the top table 2 has a structure capable of traveling in the XY directions. The laser beam 30 is irradiated from above to below.

  FIG. 9 is a main part plan view showing the movement of the top table 2 during the irradiation of the laser beam 30. FIG. 10 is a diagram showing the timing of irradiation with the laser beam 30. In these figures, the laser beam 30 is accelerated on the top table 2 and travels at a constant speed. When the laser beam 30 reaches a certain speed, the output of the laser beam 30 is repeatedly controlled to be turned on / off to a required location on the glass substrate 1. Irradiation with a laser beam 30 forms a melt recrystallization region 32.

  FIG. 11 is a flowchart showing a method of manufacturing a liquid crystal display device using the laser annealing apparatus according to the present invention. First, after forming an insulating film and an a-Si film on the glass plate 61 shown in FIG. 6 and performing excimer laser annealing, only the portion where the drive circuit is formed using the laser annealing apparatus of the present invention is melted and recrystallized. Region 32 is formed. In this case, after repeating until all the desired areas are annealed, the glass plate 61 is unloaded.

  Next, a polycrystalline silicon film is left in an island shape only in a necessary region by a photoetching process. Thereafter, impurity diffusion and activation of the diffusion region are performed by forming a gate insulating film and forming a gate electrode by a photoresist process. Thereafter, through a photoresist process such as interlayer insulating film formation, source / drain electrode formation, protective film (passivation film) formation, a drive circuit and a display unit 51 (not shown) are formed on the glass substrate 1 as shown in FIG. Thus, the glass substrate 1 on which the thin film transistor is mounted is completed.

  Thereafter, a color filter substrate (not shown) is placed on the glass substrate 1 that has undergone processes such as alignment film formation and rubbing, and a liquid crystal material is sealed therein. A liquid crystal display panel having a high-speed driving circuit is completed through a module process that is incorporated into the frame together.

  FIG. 12 is a diagram for explaining a laser output control method by the laser annealing apparatus according to the present invention. In FIG. 12, the laser annealing apparatus receives a change in laser light reflected by the table protective film 80 by the photomultiplier 100, calculates it by the laser output calculation unit 101, and issues a laser output command to the laser attenuator 102.

  For example, when the laser annealing apparatus is operated for a long time, the output intensity of laser light may change from a predetermined output intensity. However, in the laser annealing apparatus of the present invention, a change in the output intensity of the laser beam 30 can be detected using the laser beam reflected by the table protective film 80 and corrected to a predetermined output intensity.

  In the first embodiment, the case where the table protective film 80 that reflects the laser light transmitted through the glass substrate 1 is disposed on the substrate adsorption surface of the top table 2 has been described. A protective film having a sufficiently large thickness and a low reflectance may be provided. Even if the reflection of the protective film is low, the laser beam is defocused on the substrate adsorption surface of the top table 2 by maintaining a sufficient film thickness, so that the temperature of the substrate adsorption base of the top table 2 rises, deforms, dissolves, etc. Damage can be prevented and reliability can be improved as well.

  In addition, by providing an air film, that is, a gap, instead of the table protective film 80 that reflects the laser light transmitted through the glass substrate 1, the laser light transmitted through the glass substrate 1 is defocused on the substrate adsorption surface of the top table 2. Therefore, the occurrence of damage such as temperature rise, deformation and melting of the base can be prevented, and the reliability can be improved as well.

It is a figure explaining the structure by Example 1 of the laser annealing apparatus by this invention, Fig.1 (a) is the top view seen from upper direction, FIG.1 (b) is the top view seen from the side surface. It is a figure which shows the structure of the laser optical system of FIG. It is a perspective view which shows the state which irradiates a laser beam to a glass substrate. It is a top view which shows the laser irradiation area | region of the glass substrate to which this invention is applied. It is a top view which shows the positional relationship of the fusion | melting recrystallization area | region in a glass substrate, and the area | region used as the display part of a display apparatus. It is an expanded sectional view of a glass substrate. It is a principal part expanded section which shows the structure of the top table of the laser annealing apparatus by this invention. It is a principal part top view which shows the state which mounted the glass substrate on the top table of FIG. It is a principal part top view which shows the motion of the top table during irradiation of a laser beam. It is a figure which shows the timing of irradiation of a laser beam. It is a flowchart which shows the laser annealing process applied to the manufacturing method of a liquid crystal display panel as a display apparatus using the laser annealing apparatus by this invention. It is a figure explaining the laser output control system by the laser annealing apparatus by this invention. It is a principal part expanded sectional view which shows the structure of the conventional laser annealing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Glass substrate, 2 ... Top table, 3 ... XY stage, 4 ... Frame, 5 ... Anti-vibration stand, 6 ... Surface plate, 10-1 to 10-4 ..Laser oscillators, 11-1 to 11-4, beam expanders, 12-1 to 12-4, EO (electro-optic) modulators, 13-1,. , 16 ... prism, 15-1 ... mirror, 15-2 ... mirror, 17 ... DOE (diffractive optical element), 18 ... imaging lens, 19 ... cylindrical lens, 20 ... Mirror, 21 ... Imaging lens, 22 ... Objective lens, 30 ... Laser light, 32 ... Melt recrystallization region, 33 ... Glass cutting part, 51 ... Display part 61 ... Glass plate, 62 ... Passivation film, 63 ... Si Con film, 80 ... table protective film, 100 ... photomultiplier, 101 ... laser output calculation unit, 102 ... laser attenuator.

Claims (6)

Stage means on which a sample can be placed and moved;
Laser light source means for generating laser light;
Projection optical system means for projecting laser light emitted from the laser light source onto the surface of the sample;
With
A laser annealing apparatus characterized in that a protective film having a low absorption rate of laser light is provided on the adsorption surface base of the sample of the stage means.   The laser annealing apparatus according to claim 1, wherein the protective film is an air film.   The laser annealing apparatus according to claim 1, wherein the protective film is a laser light reflecting film.   The protective film is white alumina, gray alumina, titania, zirconia, chromia, zircon magnesia spines, magnesia, tungsten carbide, titanium carbide, silicon carbide, chrome carbide, aluminum, nickel, copper, nichrome, molybdenum, 4. The laser annealing apparatus according to claim 3, wherein the laser annealing apparatus is tungsten, titanium, or a mixture of these materials.   The laser annealing apparatus according to claim 4, wherein the protective film is a film formed on the adsorption surface base by a thermal spraying method. A method of manufacturing a display device having a drive circuit on a substrate,
Stage means comprising stage means capable of placing and moving a sample, laser light source means for generating laser light, and projection optical system means for projecting laser light emitted from the laser light source onto the surface of the sample. By the laser annealing apparatus provided with a protective film having a low absorption rate of laser light on the adsorption surface base of the sample,
An annealing step for annealing a portion of the substrate;
Forming the drive circuit in a region annealed by the annealing step on the substrate;
A method for manufacturing a display device, comprising:

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