WO2015180346A1

WO2015180346A1 - Laser annealing device

Info

Publication number: WO2015180346A1
Application number: PCT/CN2014/087795
Authority: WO
Inventors: 田雪雁
Original assignee: 京东方科技集团股份有限公司
Priority date: 2014-05-29
Filing date: 2014-09-29
Publication date: 2015-12-03
Also published as: CN203950784U

Abstract

A laser annealing device (10), comprising a laser transmission apparatus and an annealing window (12), wherein the laser transmission apparatus is configured to transmit a laser beam for annealing a workpiece and transmit the laser beam from the upper part of the annealing window (12) to the annealing window (12), a spray tube (13) is provided at the lower part of the annealing window, and the spray tube (13) is used for spraying a gas onto the lower surface of the annealing window (12). The laser annealing device (10) can prevent particulate matters from being attached to the lower surface of an annealing window (12) and affecting the penetration of a laser, so that the energy density of a laser beam irradiated on a workpiece is uniform, thereby being able to obtain a good annealing effect.

Description

Laser annealing equipment

Technical field

The present invention relates to the field of liquid crystal display technology, and in particular to a laser annealing apparatus used in a process for preparing a low temperature polysilicon film.

Background technique

In a low temperature polysilicon thin film transistor liquid crystal display (LTPS TFT-LCD) and an active matrix organic light emitting diode display (AMOLED), it is generally required to prepare a polysilicon film as an active layer of a thin film transistor (TFT) on an array substrate.

In the prior art, a polysilicon film is generally prepared on an array substrate by first depositing a buffer layer on a glass substrate, the buffer layer being generally a double layer, respectively a SiN _x layer and a SiO ₂ layer; secondly, A layer of amorphous silicon is deposited on the buffer layer; then, the amorphous silicon layer is subjected to high temperature treatment, generally at a temperature of 400 to 500 ° C for 0.5 to 3 hours of high temperature treatment; finally, laser annealing equipment is used for amorphous silicon The layer is annealed to convert amorphous silicon into polycrystalline silicon to obtain a polycrystalline silicon film on a glass substrate.

FIG. 1 is a schematic structural view of a conventional laser annealing apparatus. As shown in FIG. 1, the laser annealing apparatus 1 includes a laser (not shown), a package glass 2, a beam splitting unit (Slit) 3, an annealing window 4, and the like. Wherein, the laser is used to emit a laser beam, which is converted into a linear beam by the encapsulating glass 2, the beam incision unit 3 and other devices, and the linear beam passes through the annealing window 4, and is irradiated to the surface where amorphous silicon is deposited. On the glass substrate.

In the laser annealing apparatus 1 described above, when the amorphous silicon is subjected to a laser annealing process, the amorphous silicon particles 5 are detached from the amorphous silicon layer on the glass substrate, float to the annealing window 4, and adhere thereto. Thus, in the subsequent laser annealing process, the amorphous silicon particles 5 attached to the annealing window 4 block the laser beam from passing through the annealing window 4 to a certain extent, thereby reducing the utilization of the laser beam and making the irradiation to be amorphous. The energy of the laser on the silicon layer is uneven, which in turn causes unevenness and moire on the prepared polysilicon film.

Summary of the invention

The present invention aims to solve at least one of the technical problems existing in the prior art. to this end, The present invention provides a laser annealing apparatus which can prevent particles adhering to the laser from adhering to the annealing window during the annealing process, and/or remove particles attached to the annealing window after the annealing process, thereby improving the laser The transmittance of the beam passing through the annealing window is made uniform, and the energy of the laser light irradiated onto the amorphous silicon layer is made uniform, thereby obtaining a uniform annealing effect.

To achieve the object of the present invention, there is provided a laser annealing apparatus comprising a laser emitting device and an annealing window, the laser emitting device being configured to emit a laser beam for annealing a workpiece, and to apply the laser beam from An annealing window is directed above the annealing window, and a nozzle is provided below the annealing window for injecting gas to the lower surface of the annealing window.

Preferably, the laser annealing apparatus further includes a gas source in communication with the nozzle, the gas source for supplying gas to the nozzle.

Preferably, the gas is nitrogen.

Preferably, the number of the nozzles is plural.

Preferably, a plurality of the nozzles are respectively disposed on opposite sides of the annealing window, and the nozzles of the nozzles on either side face the other side opposite to the side, and are located on both sides of the annealing window. A plurality of the nozzles are staggered.

Preferably, the laser beam for annealing the workpiece is a linear laser beam.

Preferably, the laser emitting device includes a laser and a laser beam converting unit for emitting a laser beam, and the laser beam converting unit is configured to convert the laser beam emitted by the laser into a linear laser beam.

Preferably, the laser is one of a ruthenium chloride excimer laser, a ruthenium fluoride excimer laser, and an argon fluoride excimer laser.

Preferably, the laser annealing apparatus further includes a laser adjusting device for adjusting an energy density of the laser beam.

The invention has the following beneficial effects:

In the laser annealing apparatus provided by the present invention, a nozzle is provided below the annealing window. When the nozzle sprays gas to the lower surface of the annealing window during the annealing process, the particles can be prevented from adhering to the lower surface of the annealing window by purging, so that the entire surface of the annealing window is not blocked during the entire process of the laser annealing process. The particles that the laser beam passes through. In addition, When the nozzle ejects gas to the lower surface of the annealing window after the annealing process is finished, the particles attached to the lower surface of the annealing window can be removed by purging to facilitate the subsequent step of irradiating the laser beam. This makes the energy of the laser beam irradiated onto the respective regions of the workpiece through the annealing window uniform, so that a uniform annealing effect can be obtained.

DRAWINGS

The drawings are intended to provide a further understanding of the invention, and are intended to be a In the drawing:

1 is a schematic structural view of a conventional laser annealing apparatus;

2 is a schematic diagram of a laser annealing apparatus according to an embodiment of the present invention;

Figure 3 is a bottom plan view of the annealing window in the laser annealing apparatus shown in Figure 2;

4 is a schematic cross-sectional view of a glass substrate.

Description of the reference numerals

1: laser annealing equipment; 2: package glass; 3: beam incision unit; 4: annealing window; 5: amorphous silicon particles;

10: laser annealing equipment; 12: annealing window; 13: nozzle; 110: laser beam conversion unit; 111: package glass; 112: beam cutting unit; 20: glass substrate; 21: SiN _x layer; 22: SiO ₂ Layer; 23 amorphous silicon layer.

detailed description

The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative and not restrictive.

In the present invention, the direction of the laser emitting device with respect to the annealing window 12 is "up", and the direction of the annealing window 12 with respect to the laser emitting device is "down".

Please refer to FIG. 2. FIG. 2 is a schematic diagram of a laser annealing apparatus according to an embodiment of the present invention. The laser annealing apparatus 10 includes a laser emitting device and an annealing window 12. The laser emitting device is capable of emitting a laser beam for annealing the workpiece, and the laser beam is self-annealed The upper portion of 12 is directed toward the annealing window 12. Specifically, the laser beam used to anneal the workpiece is a linear laser beam. The laser emitting device includes a laser (not shown) and a laser beam converting unit 110, wherein the laser is used to emit a laser beam, and the laser beam converting unit 110 is configured to convert the laser beam emitted by the laser into a line that can anneal the workpiece. Laser beam. Preferably, in the present embodiment, the laser is one of a ruthenium chloride excimer laser, a ruthenium fluoride excimer laser, and an argon fluoride excimer laser. The laser conversion unit 110 includes a package glass 111 and a beam splitting unit 112.

A nozzle 13 is disposed under the annealing window 12 for injecting gas toward the lower surface of the annealing window 12 to prevent particulate matter from adhering to the lower surface of the annealing window 12 by purging during the annealing process. Laser penetration affects. Specifically, the nozzle 13 is in communication with a source of gas (not shown) for providing gas to the nozzle 13 for injection. In the present embodiment, preferably, the gas is nitrogen.

Preferably, in the present embodiment, the number of the nozzles 13 is plural, which are respectively disposed on opposite sides of the annealing window 12, and the nozzles of the nozzles 13 on either side face each other opposite to the side. One side. A plurality of nozzles 13 located on either side of the annealing window 12 are staggered, i.e., the nozzles 13 on either side are opposed to the spacing between the respective nozzles on the other side, as shown in FIG. Such an arrangement makes it possible to inject gas from opposite sides of the annealing window 12 to the opposite side, and the gases ejected from both sides do not interfere with each other, so that the surface which may adhere to the surface of the annealing window 12 can be removed more efficiently and more thoroughly. particulates.

The flow of the annealing process of the laser annealing apparatus provided in this embodiment will be described below with reference to the accompanying drawings.

Taking the preparation process of the polysilicon film as an example, the preparation process of the polysilicon film includes the following steps:

S1. The glass substrate 20 is cleaned to remove dust and particulate matter on the glass substrate 20.

S2, depositing a buffer layer on the glass substrate 20. Preferably, as shown in FIG. 4, the buffer layer comprises two layers, a SiN _x layer 21 and an SiO ₂ layer 22, respectively. Specifically, the step of depositing the buffer layer includes first depositing a SiN _x layer 21 on the glass substrate 20 by a plasma enhanced chemical vapor deposition (PECVD) method, which may have a thickness of 50 to 150 nm; and then, on the SiN _x layer 21 The SiO ₂ layer 22 is deposited and may have a thickness of 100 to 350 nm.

S3, depositing an amorphous silicon layer 23 on the buffer layer. The amorphous silicon layer 23 is typically deposited by a PECVD method, preferably having a thickness of 30 to 60 nm.

S4, the amorphous silicon layer 23 is subjected to high temperature treatment. Specifically, the glass substrate 20 is placed at a temperature of 400 to 500 ° C and subjected to a high temperature treatment for 0.5 to 3 hours.

S5. The amorphous silicon layer 23 is annealed by the laser annealing apparatus provided in this embodiment, and the amorphous silicon layer 23 is converted into polycrystalline silicon to obtain a polycrystalline silicon thin film on the glass substrate.

Specifically, in step S5, the laser emitting device emits a linear laser beam. The linear laser beam is directed toward the annealing window 12 from above the annealing window 12, and is irradiated onto the amorphous silicon layer 23 after passing through the annealing window 12, so that the amorphous silicon layer 23 can be subjected to a laser annealing process. In addition, by moving the glass substrate 20, the laser beam can completely scan the entire glass substrate 20, thereby completing annealing of the amorphous silicon layer 23 on each of the regions of the glass substrate 20. Preferably, in the process, the laser beam has a pulse frequency of 500 Hz, an overlap ratio of 92% to 98%, a laser scanning rate of 4 to 16 mm/s, and an energy density of the laser beam of 300 to 500 mJ/cm ² .

S6, spraying a gas through the nozzle 13 toward the lower surface of the annealing window 12 to prevent the particles from adhering to the lower surface of the annealing window 12.

Since a part of the amorphous silicon particles usually detach from the amorphous silicon layer 23 and float to the annealing window 12 during the annealing process, during the annealing process of the amorphous silicon layer 23 on the glass substrate 20, Amorphous silicon particles may be attached to the annealing window 12. Thus, in the present invention, a gas (such as nitrogen) is sprayed toward the lower surface of the annealing window 12 by means of the nozzle 13, and the particles are prevented from adhering to the lower surface of the annealing window 12 by purging, so that during the entire annealing process, On the annealing window 12, there is no particulate matter that hinders the passage of the laser light, and the energy of the laser beam irradiated onto the amorphous silicon layer 23 is made uniform, so that a uniform polycrystalline silicon thin film can be obtained on the glass substrate 20.

Preferably, in the present embodiment, the laser annealing apparatus further includes laser adjusting means for adjusting the energy density of the laser beam to meet the needs of different annealing processes.

In the laser annealing apparatus 10 provided in this embodiment, a nozzle 13 is provided below the annealing window 12. During the annealing process, the nozzle 13 injects gas toward the lower surface of the annealing window 12 to prevent particulate matter from adhering to the lower surface of the annealing window 12 by purging. Thus, during the entire laser annealing process, there is no blocking laser beam on the lower surface of the annealing window 12. The particles that pass through are such that the energy of the laser beam irradiated onto the respective regions of the workpiece through the annealing window 12 is uniform, so that a uniform annealing effect can be obtained.

It should be noted that, in this embodiment, the number of the nozzles 13 is plural, which are respectively disposed on opposite sides of the annealing window 12, so that the nozzles of the nozzles on either side face toward the side. On the other side, a plurality of nozzles 13 on either side of the annealing window 12 are staggered. However, the invention is not limited to this. In a practical application, the nozzle 13 can also be disposed on the annealing window 12 in other manners. For example, a plurality of nozzles 13 may be disposed on one side of the annealing window 12, on adjacent sides of the annealing window 12, and on each side of the annealing window 12, and the like. Further, the number of the nozzles 13 may be one depending on the need to purge the particulate matter.

Further, although in the above detailed description of the embodiment, the ejection of the gas from the nozzle 13 to the lower surface of the annealing window 12 is performed during the annealing process, it is understood that it may also be performed after the annealing process is completed. The step of injecting gas through the nozzle 13 toward the lower surface of the annealing window 12 to remove particulate matter attached to the lower surface of the annealing window 12 during the annealing process by purging. Thus, at the next step of irradiating the laser, there is no particulate matter on the lower surface of the annealing window 12 that blocks the passage of the laser beam, so that the energy of the laser beam irradiated to the respective regions of the workpiece through the annealing window 12 is uniform.

It is to be understood that the above embodiments are merely exemplary embodiments employed to explain the principles of the invention, but the invention is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and scope of the invention. These modifications and improvements are also considered to be within the scope of the invention.

Claims

A laser annealing apparatus comprising a laser emitting device and an annealing window, the laser emitting device configured to emit a laser beam for annealing a workpiece, and directing the laser beam from above the annealing window to the An annealing window, characterized in that a nozzle is provided below the annealing window for injecting gas to the lower surface of the annealing window.
A laser annealing apparatus according to claim 1, wherein said laser annealing apparatus further comprises a gas source in communication with said nozzle, said gas source for supplying gas to said nozzle.
A laser annealing apparatus according to claim 1 or 2, wherein the gas is nitrogen.
The laser annealing apparatus according to claim 1, wherein the number of the nozzles is plural.
The laser annealing apparatus according to claim 4, wherein a plurality of said nozzles are respectively disposed on opposite sides of said annealing window, and nozzles of nozzles on either side face each other opposite to said side On the other side, a plurality of the nozzles located on both sides of the annealing window are staggered.
The laser annealing apparatus according to claim 1, wherein the laser beam for annealing the workpiece is a linear laser beam.
The laser annealing apparatus according to claim 1 or 6, wherein said laser emitting device comprises a laser and a laser beam converting unit, said laser for emitting a laser beam, said laser beam converting unit for said The laser beam emitted by the laser is converted into a linear laser beam.
The laser annealing apparatus according to claim 7, wherein said laser is one of a ruthenium chloride excimer laser, a ruthenium fluoride excimer laser, and an argon fluoride excimer laser.
The laser annealing apparatus according to claim 1, wherein said laser annealing apparatus further comprises laser adjusting means for adjusting an energy density of said laser beam.