WO2020129601A1

WO2020129601A1 - Laser annealing method and laser annealing apparatus

Info

Publication number: WO2020129601A1
Application number: PCT/JP2019/047137
Authority: WO
Inventors: 水村　通伸
Original assignee: 株式会社ブイ・テクノロジー
Priority date: 2018-12-19
Filing date: 2019-12-03
Publication date: 2020-06-25
Also published as: TW202032631A; JP2020098895A

Abstract

A laser annealing method comprises: a seed crystal region formation step for performing first irradiation by irradiating the surface of an amorphous silicon film with a first laser beam spot formed by a first laser beam in a wavelength range that is absorbed by amorphous silicon and melting the amorphous silicon to form a seed crystal region; and a modified region formation step for performing second irradiation by irradiating a region adjacent to the first laser beam spot with a second laser beam spot formed by a second laser beam in a wavelength range that is absorbed by the molten silicon after the silicon in the seed crystal region has been melted by performing the first irradiation, and growing crystallized silicon in a modified region continuous with the seed crystal region starting from the seed crystal region.

Description

Laser annealing method and laser annealing apparatus

The present invention relates to a laser annealing method and a laser annealing apparatus.

In recent years, it has been known that by irradiating an amorphous silicon film with continuous wave laser light, the grain size of crystals formed in the amorphous silicon film is increased and a pseudo single crystal silicon film is formed. There is. By applying this pseudo single crystal silicon film to the channel layer of a thin film transistor (TFT), the mobility of the channel layer can be increased.

In the conventional laser annealing method using continuous wave laser light, the laser annealing process was performed using a single wavelength laser having a wavelength that is absorbed by the amorphous silicon film to be annealed. In particular, since a laser wavelength having a high absorptivity with respect to an amorphous silicon film is ultraviolet, a semiconductor laser needs to have a wavelength range of about 400 to 450 nm. However, the output of the semiconductor laser is about several W, and in order to perform the laser annealing process on a wide area, a structure has been proposed in which a plurality of semiconductor lasers are collectively output. Therefore, the conventional laser annealing method using continuous wave laser light has problems that the efficiency of the laser annealing process is low and the cost is high.

As another conventional laser annealing method, a first laser beam having a wavelength of visible light or shorter is processed so that the irradiation surface has a long beam, and a basic laser beam is applied to a portion having a low energy density in the first laser beam. A technique of irradiating a second laser beam formed of waves is known (for example, refer to Patent Document 1). In this conventional laser annealing method, a gas laser, a solid-state laser, and a metal laser are used as the laser.

In the laser annealing method disclosed in Patent Document 1, the energy density is complemented by arranging the second laser beam so as to surround and cover the outer circumference of the beam on the irradiation surface of the first laser beam. A region where the second laser beam is superposed is calculated from the distribution of the energy density of the first laser beam, and the energy density in the entire superposed region is averaged. In the laser annealing method disclosed in Patent Document 1, in order to average the energy density, the reflected light from the front surface of the substrate and the reflected light from the rear surface of the substrate at a predetermined incident angle of the laser beam are used. , Are designed so as to form a uniform laser beam without interference.

JP, 2010-283073, A

However, in the laser annealing method disclosed in Patent Document 1, a region irradiated with a laser beam having a wavelength that is not absorbed by the amorphous silicon film that is the film to be processed even if the energy density of the laser beam is averaged. Then, the crystallization cannot be performed, and even if the crystallization is possible, the crystal growth may be irregular. Further, in the laser annealing method disclosed in Patent Document 1, since a gas laser or a solid laser is used, there is a problem that equipment cost and maintenance cost increase.

The present invention has been made in view of the above problems, and an object thereof is to provide a laser annealing method and a laser annealing apparatus that can form a crystallized silicon film in a region having a required area at low cost. And

In order to solve the above-mentioned problems and to achieve the object, an aspect of the present invention is to relatively move a substrate to be processed having an amorphous silicon film formed on its surface with respect to a beam spot of a laser beam. A laser annealing method for irradiating the amorphous silicon film with the beam spot to modify it into a crystallized silicon film, wherein a wavelength range absorbed by the amorphous silicon is formed on the surface of the amorphous silicon film. A first laser beam spot of a first laser beam to melt the amorphous silicon to form a seed crystal region, and a seed crystal region forming step of forming a seed crystal region; In a state where the silicon is melted by performing one irradiation, the second laser beam spot formed by the second laser light in the wavelength range absorbed by the melted silicon is irradiated to a region adjacent to the first laser beam spot. A modified region forming step of performing second irradiation and growing crystallized silicon in a modified region continuous with the seed crystal region starting from the seed crystal region.

In the above aspect, it is preferable that the wavelength range of the first laser light is near ultraviolet to visible light, and the wavelength range of the second laser light is visible light or more.

In the above aspect, it is preferable that each of the first laser light and the second laser light is emitted from a semiconductor laser.

In the above aspect, the power density of the first laser light is preferably lower than the power density of the second laser light.

In the above aspect, it is preferable that the first laser beam spot is arranged at the same position or downstream of the second laser beam spot in the carrying direction of the substrate to be processed.

In the above aspect, the first laser beam spot is arranged so as to pass through a part of the modified region, and the second laser beam spot is formed so as to pass over the entire surface of the modified region. Is preferred.

In the above aspect, it is preferable that the plurality of second laser beam spots are formed so as to extend from the first laser beam spot.

In the above aspect, it is preferable that the second laser beam spot is arranged so as to extend from the first laser beam spot toward an obliquely upstream side in the transport direction of the substrate to be processed.

According to another aspect of the present invention, the amorphous silicon film is set so as to move relative to a beam spot of a laser beam on a substrate on which the amorphous silicon film is formed. Is a laser annealing apparatus for irradiating the laser beam with the beam spot to modify the crystallized silicon film, the first light source oscillating a first laser beam in a wavelength range absorbed by the amorphous silicon film. And a first light source unit that oscillates a second laser beam in a wavelength range that is absorbed by the melted silicon, and irradiates a first laser beam spot of the first laser beam to the amorphous state. The silicon film is melted, and the silicon melted by the first laser light is irradiated with a second laser beam spot of the second laser light in an area adjacent to the first laser beam spot.

In the above aspect, it is preferable that the power density of the first laser light is set lower than the power density of the second laser light.

In the above aspect, it is preferable that the first laser beam spot is located at the same position or downstream of the second laser beam spot in the carrying direction of the substrate to be processed.

In the above aspect, the first laser beam spot is arranged so as to pass through a part of the modified region, and the second laser beam spot is formed so as to pass over the entire surface of the modified region. It is preferable.

According to the present invention, it is possible to realize a laser annealing method and a laser annealing apparatus capable of forming a crystallized silicon film in a region having a required area at low cost.

FIG. 1 is a flowchart showing a laser annealing method according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a laser annealing apparatus used in the laser annealing method according to the embodiment of the present invention. FIG. 3 is an explanatory view schematically showing an arrangement example of micromirrors in the laser annealing apparatus used in the laser annealing method according to the embodiment of the present invention. FIG. 4 is an explanatory diagram showing a beam spot (indicated by diagonal hatching) when the first irradiation for forming the seed crystal region in the amorphous silicon film is performed in the laser annealing method according to the embodiment of the present invention. is there. FIG. 5 shows a beam spot (indicated by hatching in a grid pattern) when the first irradiation and the second irradiation are performed simultaneously in the laser annealing method according to the embodiment of the present invention, and the seed crystal region is used as a starting point. FIG. 9 is an explanatory view showing a state in which a pseudo single crystal silicon film has started to be formed. FIG. 6 is an explanatory diagram showing a beam spot (indicated by diagonal hatching) when the first irradiation is stopped and only the second irradiation is performed in the laser annealing method according to the embodiment of the present invention. FIG. 7 is an explanatory diagram showing a state in which a pseudo single crystal silicon film is grown in a wide region in the laser annealing method according to the embodiment of the present invention. FIG. 8 is an explanatory diagram showing an imaging optical system in an MLA laser annealing apparatus as another laser annealing apparatus used in the laser annealing method according to the embodiment of the present invention. FIG. 9 is a plan view showing a mask in an MLA laser annealing apparatus as another laser annealing apparatus used in the laser annealing method according to the embodiment of the present invention.

The details of the laser annealing method and the laser annealing apparatus according to the embodiment of the present invention will be described below with reference to the drawings. However, it should be noted that the drawings are schematic, and the number of each member, the size of each member, the ratio of sizes, the shape, and the like are different from the actual ones. In addition, the drawings include portions having different dimensional relationships, ratios, and shapes.

[Embodiment] (Substrate to be processed)
In the laser annealing method, a laser annealing apparatus 10 as shown in FIG. 2 is used to perform laser annealing processing on the substrate 1 to be processed. As shown in FIG. 2, the substrate 1 to be processed includes a glass substrate 2, a plurality of gate wirings 3 arranged on the surface of the glass substrate 2, a glass substrate 2 and a gate insulation formed on the gate wiring 3. The film 4 and the amorphous silicon film 5 deposited on the entire surface of the gate insulating film 4 are provided. The substrate 1 to be processed finally becomes a TFT substrate in which a thin film transistor (TFT) or the like is built.

(Schematic configuration of laser annealing device)
Prior to the description of the laser annealing method according to this embodiment, the schematic configuration of the laser annealing apparatus 10 according to this embodiment will be described below. As shown in FIG. 2, the laser annealing apparatus 10 includes a base 11, a first laser light source unit 12A, a second laser light source unit 12B, a laser beam irradiation unit 13, and a control unit 14.

In the present embodiment, the laser beam irradiation unit 13 does not move during the annealing process, but the substrate 1 to be processed is moved. The base 11 is provided with a substrate transfer means (not shown). In the laser annealing apparatus 10, the substrate 1 to be processed is placed on the base 11 and is transported in the transport direction (scanning direction) T by a substrate transport means (not shown).
In the present embodiment, the transport direction T shown in FIGS. 4 to 7 may be the longitudinal direction of the gate wiring 3 or a direction orthogonal to the longitudinal direction.

As shown in FIG. 2, the first laser light source unit 12A emits a first semiconductor laser 25 that oscillates a first laser beam and a light beam that emits a laser beam LB toward the laser beam irradiation unit 13. And a section 26.

The first semiconductor laser 25 uses, as the first laser light, one that oscillates continuous-wave laser light (CW laser light) having a wavelength range of 400 to 500 nm, such as purple, blue, green blue, blue green, and green. The first laser light in such a wavelength range can be absorbed by the amorphous silicon forming the amorphous silicon film 5 to melt the amorphous silicon. The laser beam irradiation unit 13 selectively reflects the first laser light to irradiate the first laser beam spot LBS1 (first irradiation) on the surface of the amorphous silicon film 5, as shown in FIG. It has become. The output of the first semiconductor laser 25 is, for example, about several watts because it irradiates only the portion corresponding to the DMD spot region.

As shown in FIG. 2, the second laser light source unit 12B emits a second semiconductor laser 15 that oscillates a second laser beam and a laser beam LB that directs the second laser beam to the laser beam irradiation unit 13. And a section 17.

The second semiconductor laser 15 oscillates, as the second laser light, continuous wave laser light (CW laser light) having a wavelength range of visible light or more, for example, near infrared light. The second laser light in this wavelength range is absorbed by the silicon melted by the first irradiation with the first laser beam spot LBS1 and is amorphous in a region adjacent to the region irradiated with the first laser beam spot LBS1. The silicon film 5 is melted in the transport direction T and in a direction orthogonal to the transport direction T.

This second laser light is selectively reflected by the laser beam irradiation unit 13, and as shown in FIG. 5, the first laser beam spot LBS1 and the second laser beam adjacent thereto are formed on the surface of the amorphous silicon film 5. Both spots LBS2 are irradiated (second irradiation). As shown in FIG. 4, the second laser beam spots LBS2 are, for example, formed in a pair so as to have a substantially V shape. Each second laser beam spot LBS2 is formed so as to extend from the first laser beam spot LBS1 shown in a small circle shape. The second laser beam spot LBS2 is arranged so as to extend from the first laser beam spot LBS1 toward an obliquely upstream side in the transport direction T of the substrate to be processed. The output of the second semiconductor laser 15 is, for example, about 50 W because it is applied only to the part corresponding to the spot area of the DMD.

As described above, the first laser light source unit 12A and the second laser light source unit 12B emit the first laser light and the second laser light toward the laser beam irradiation unit 13. The laser beam irradiation unit 13 receives the laser beams of the first laser beam and the second laser beam by a digital micromirror device 18 described later, and selectively forms a first laser beam spot LBS1 on the surface of the substrate 1 to be processed. The second laser beam spot LBS2 is irradiated.

As shown in FIG. 2, the laser beam irradiation unit 13 is arranged above the base 11 by a support frame or the like (not shown). The laser beam irradiation unit 13 includes a digital micromirror device (DMD: Digital Micromirror Device, registered trademark of Texas Instruments) 18, a damper (absorber) 19, a microlens array 20, and a projection. And a lens 21.

As shown in FIGS. 2 and 3, a digital micromirror device (hereinafter referred to as DMD) 18 includes a drive substrate (CMOS substrate) 22 and a large number of micromirrors (thin film mirrors) 23 (23A to 23F: A to F). The columns are respectively labeled with 1 to 6). In the present embodiment, for convenience of description, the number of micromirrors 23 will be described as 36, but the actual number is more than the number of pixels for high-definition television. The micromirror 23 is formed in a square shape having a side length of, for example, about ten and several μm. A large number of pixel regions are arranged in a matrix on the drive substrate 22, and a CMOS SRAM cell is formed in each pixel region.

The micro mirror 23 is arranged on the drive substrate 22 so as to correspond to each CMOS SRAM cell. The micro mirror 23 is provided by the MEMS (Micro Electro Mechanical Systems) technology. Each micro mirror 23 is provided so as to be movable to two positions. Specifically, for example, it is configured to be rotationally moved to two positions forming an angle of +10 degrees and an angle of −10 degrees with respect to the substrate surface. The micro mirror 23 is driven so as to be displaced to the above two positions in accordance with the output data from the CMOS SRAM cell side.

As shown in FIG. 3, the first laser beam spots LBS1 from the first laser light source unit 12A and the second laser light source unit 12B side are simultaneously or in any one of the plurality of micro mirrors 23 forming the array. Then it is incident. The respective micro mirrors 23 (23A to 23F) are set so as to reflect a part of the laser light of the laser beam LB in two directions by selectively moving to the above two positions. ..
One of these two directions is a direction in which a part of the laser light of the laser beam LB is directed to the damper 19, and the other of the two directions is a part of the laser beam LB. This is the direction in which light is directed to the surface of the substrate 1 to be processed.

In FIG. 3, a pair of micromirrors 23A3 and 23A4 is used to create the first laser beam spot LBS1, and 23D1, 23C2, 23B3, 23B4, 23C5 and 23D6 arranged in a substantially V shape are the second laser beam spots. Used to create LBS2.

The damper 19 is arranged at a position for receiving the laser beam reflected by the micro mirror 23 in the off state when the micro mirror 23 is in the off state (for example, the angle with respect to the drive substrate 22 is −10 degrees, non-irradiation state). Has been done.

The microlens array 20 focuses each laser beam reflected by the micromirror 23 in the on state (for example, the angle with respect to the drive substrate 22 is +10 degrees, the irradiation state) toward the projection lens 21. The projection lens 21 is set so as to image the introduced laser beam on the surface of the substrate 1 to be processed as a part of the first laser beam spot LBS1 or the second laser beam spot LBS2.

The control unit 14 controls the substrate transfer means (not shown) provided on the base 11, the first laser light source unit 12A, the second laser light source unit 12B, and the DMD 18.

First, the control unit 14 is set to drive and control the substrate transfer means (not shown) to move the substrate 1 to be processed in the transfer direction T at a predetermined speed.

In addition, the control unit 14 drives and controls the first laser light source unit 12A, the second laser light source unit 12B, and the laser beam irradiation unit 13 to perform the first irradiation and the first irradiation on the substrate 1 to be processed. It is set to perform two irradiations.

In the first irradiation, the first laser light is emitted from the first laser light source unit 12A, and the laser beam reflected by the micromirrors 23A3 and 23A4 is applied to the surface of the amorphous silicon film 5 of the substrate 1 to be processed by the first laser beam. Irradiate as spot LBS1.

In the second irradiation, the second laser light is emitted from the second laser light source unit 12B, and the laser beam reflected by the micromirrors 23D1, 23C2, 23B3, 23B4, 23C5, 23D6 is an amorphous silicon film on the substrate 1 to be processed. The surface of No. 5 is irradiated with the second laser beam spot LBS2. In the present embodiment, the second laser light is also applied to the first laser beam spot LBS1.

The control unit 14 causes the laser light source unit 12 to continuously emit the CW laser light as the second laser light in the second irradiation. When the first irradiation and the second irradiation are not performed, the laser light source unit 12 is turned off, or all the micromirrors 23 (23A to 23F) in the DMD 18 are turned off so that the laser beam LB is reflected toward the damper 19. Is set to state. The first irradiation and the second irradiation selectively turn on/off the micromirrors 23 (23A to 23F), so that the micromirrors 23A3 and 23A4 are arranged in a substantially V-shape. A group of mirrors 23D1, 23C2, 23B3, 23B4, 23C5, 23D6 can also be selected.

The control unit 14 controls to start the first irradiation at the most downstream portion in the transport direction of the reforming area where the reforming is performed. Further, the control unit 14 is set to start the second irradiation at the same time as the start of the above-mentioned first irradiation or after a predetermined time from the first irradiation. In the present embodiment, the control unit 14 outputs a drive signal to the DMD 18 when the amorphous silicon film 5 moves to a predetermined position based on position information data of a substrate position detection sensor (not shown). It is set. The DMD 18 to which the drive signal is input is controlled to turn on a predetermined micromirror 23.

When the plurality of micromirrors 23 are turned on, the laser beam LB composed of the laser light emitted from the first laser light source unit 12A or the second laser light source unit 12B is reflected by the predetermined micromirrors 23 to be processed. It is incident on the surface of the substrate 1.

As shown in FIG. 4, the laser beams reflected from the respective micro mirrors 23 are first irradiated onto a predetermined position of the amorphous silicon film 5 to irradiate a first laser beam spot LBS1. In the first-irradiated amorphous silicon film 5, a seed crystal region 5A made of microcrystalline silicon can be formed as shown in FIG.

As shown in FIG. 5, the control unit 14 controls the first laser light source unit 12A, the second laser light source unit 12B, and the laser beam irradiation unit when the amorphous silicon film 5 slightly moves based on the position information. It is set so that the first irradiation and the second irradiation are performed at the same time by controlling the driving of No. 13.

Thereafter, as shown in FIG. 6, the control unit 14 irradiates the second laser beam spot LBS2 composed of the second laser light with the seed crystal region 5A as a starting point in a state where the first irradiation is stopped. It is set to perform two irradiations.

The control unit 14 is set to stop the second irradiation when the locus of the second laser beam spot LBS2 passes through the entire surface of the modified region.

As shown in FIGS. 6 and 7, the second irradiation sets conditions such that the amorphous silicon film 5 becomes a pseudo single crystal (hereinafter also referred to as lateral crystal) silicon film 5B as a crystallized silicon film. ing. The pseudo single crystal silicon film 5B constitutes a modified region.

The substrate 1 to be processed used in the laser annealing method according to the present embodiment, the laser annealing apparatus 10 and the operation and operation thereof have been described above. The laser annealing method using these will be described below.

(Laser annealing method)
According to the laser annealing method of the present invention, the surface of the amorphous silicon film 5 is irradiated with the first laser beam spot LBS1 of the first laser light in the wavelength range absorbed by the amorphous silicon to remove the amorphous silicon. A seed crystal region forming step of forming a seed crystal region 5A by performing a first irradiation for melting, and a wavelength absorbed by the melted silicon in a state where the first irradiation is performed on the seed crystal region 5A to melt the silicon. The second irradiation for irradiating the region adjacent to the first laser beam spot LBS1 with the second laser beam spot LBS2 of the second laser light in the region is performed, and the modified region is continuous with the seed crystal region 5A from the seed crystal region 5A as a starting point. A modified region forming step of growing crystallized silicon (pseudo single crystal silicon).

Hereinafter, the laser annealing method according to the present embodiment will be described based on the flowchart of FIG. The laser annealing method according to the present embodiment is used in a method for manufacturing a thin film transistor, and is composed of steps S4 to S7 described below.

First, as shown in FIG. 1, a substrate 1 to be processed in which a gate wiring 3, a gate insulating film 4 and an amorphous silicon film 5 are formed on a glass substrate 2 is prepared (step S1).

Next, the substrate 1 to be processed is washed (step S2). Since the cleaned amorphous silicon film 5 of the substrate 1 to be processed contains hydrogen, the dehydrogenation process is performed, for example, at about 450° C. for several hours (step S3).

As shown in FIG. 2, the substrate 1 to be processed is set on the base 11 of the laser annealing apparatus 10 and is moved along the transport direction T at a predetermined scan speed.

Next, as a seed crystal region forming step, first irradiation for forming a seed crystal is performed (step S4). In step S4, the control unit 14 outputs a drive signal to the DMD 18 when the region to be modified reaches a predetermined position based on the position information of the amorphous silicon film 5.
Based on the drive signal, the DMD 18 turns on only the preset pair of micromirrors 23A3 and 23A4.

FIG. 4 shows a state in which the laser beam LB emitted from the first laser light source unit 12A is reflected by the on-states 23A3 and 23A4 and only the first laser beam spot LBS1 is irradiated on the amorphous silicon film 5. .. Although the irradiation region of the second laser beam spot LBS2 is shown in FIG. 4, the second laser beam is not actually irradiated to the amorphous silicon film 5. The area irradiated with the first laser beam spot LBS1 is melted by the first laser light (wavelength range 400 to 500 nm).

After that, when the substrate 1 to be processed moves extremely slightly in the transport direction T, the melted silicon is cooled and becomes the seed crystal region 5A made of microcrystalline silicon.

Next, as shown in FIG. 5, while the seed crystal region 5A is being irradiated with the first laser beam spot LBS1, second irradiation is simultaneously performed (step S5). In the second irradiation, the micromirrors 23D1, 23C2, 23B3, 23B4, 23C5, 23D6 are turned on, and the second laser beam (wavelength range 800 nm or more) is irradiated as the second laser beam spot LBS2.
At this time, the second laser light is also applied to the region of the first laser beam spot LBS1 via the micro mirrors 23A3 and 23A4. Further, the first laser light is applied to the region of the second laser beam spot LBS2 via the micro mirrors 23D1, 23C2, 23B3, 23B4, 23C5, 23D6. Therefore, in FIG. 5, the first laser beam spot LBS1 and the second laser beam spot LBS2 are indicated by the same lattice-shaped hatching.

As a result of performing step S5, as shown in FIG. 6, the pseudo single crystal silicon is formed in the transport direction T and in a direction orthogonal to the transport direction T so as to be continuous with the seed crystal region 5A as a starting point. The film 5B grows widely and becomes a modified region.

Next, as shown in FIG. 6, only the second irradiation is performed with the first irradiation stopped (step S6). In addition, as shown in FIG. 6, in the second irradiation, the region of the first laser beam spot LBS1 is also irradiated with the second laser light. Therefore, in FIG. 6, the first laser beam spot LBS1 uses the same hatching as the second laser beam spot LBS2. Then, after the pseudo single crystal (lateral crystal) silicon film 5B is formed over the predetermined region, the second irradiation is stopped and the laser annealing process ends (step S7).

In the laser annealing method according to the present embodiment, although the region where the seed crystal region 5A is formed has a small area, the pseudo single crystal silicon film 5B starts from the seed crystal region 5A and is transferred in the transport direction T. In addition, it is possible to grow widely in a direction orthogonal to the transport direction T. Grain boundaries 5GB as shown in FIG. 7 are formed in the pseudo single crystal silicon film 5B. The grain boundaries 5GB extend in the width direction (direction orthogonal to the transport direction T) from the seed crystal region 5A, and then regularly extend in parallel along the transport direction T. In addition, as shown in FIGS. 4 to 7, in the present embodiment, the substrate 1 to be processed is moved along the transport direction T, but it may be opposite to the transport direction T.

In the present embodiment, it is possible to perform the first irradiation by using the inexpensive first semiconductor laser 25 having a low power density. In addition, according to the present embodiment, it is possible to use the second semiconductor laser 15 that oscillates near-infrared light, which could not be conventionally used for annealing the amorphous silicon film 5. Therefore, in the laser annealing method and the laser annealing apparatus according to the present embodiment, the equipment cost can be significantly reduced.

In the laser annealing method and the laser annealing apparatus 10 according to the present embodiment, by using the DMD 18 as the spatial light modulator, it is possible to easily create a laser beam only by turning on/off the micromirror 23. ..

Further, in the laser annealing apparatus 10 according to the present embodiment, it becomes easy to arbitrarily form the shapes of the first laser beam spot LBS1 and the second laser beam spot LBS2 emitted by the first irradiation and the second irradiation, The size of the region to be laser-annealed can be easily followed.

In the present embodiment, since the first laser light source unit 12A and the second laser light source unit 12B use the semiconductor laser, the weight of the apparatus can be reduced, the substrate 1 to be processed is fixed, and the first laser light source unit 12A. The second laser light source unit 12B and the laser beam irradiation unit 13 may be moved. Therefore, it is possible to suppress an increase in the footprint of the device.

(Other laser annealing devices used for laser annealing method)
FIG. 8 shows an imaging optical system of an MLA laser annealing apparatus that can be used in the laser annealing method according to the embodiment of the present invention. FIG. 9 shows a mask 28 used in the image forming optical system of this MLA laser annealing apparatus. This MLA laser annealing device also includes a first laser light source unit 12A and a second laser light source unit 12B, similar to the laser annealing device 10 according to the above embodiment.

In this MLA laser annealing apparatus, as shown in FIG. 9, in a mask 28, a first irradiation opening 28S1 for forming a first laser beam spot LBS1 and a second irradiation opening 28S1 for forming a second laser beam spot LBS2 are formed. The irradiation opening 28S2 is formed. The first irradiation opening 28S1 is used to form the seed crystal region 5A, and the second irradiation opening 28S2 is used to form the pseudo single crystal silicon film 5B.

[Other Embodiments]
Although the embodiments have been described above, it should not be understood that the description and drawings forming part of the disclosure of the embodiments limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

In the above-described embodiment, as shown in FIG. 4, the second irradiation is stopped during the first irradiation for forming the seed crystal region 5A. However, the first irradiation and the second irradiation are simultaneously mixed. You may go in the state. Further, as shown in FIG. 6, after the seed crystal region 5A is formed, the first irradiation is stopped and only the second irradiation is performed. However, both irradiations may be performed without stopping the first irradiation. It is possible.

In the above embodiment, as shown in FIGS. 4 to 7, the second laser beam spot LBS2 has a substantially V shape, but the shape is not limited to such a shape. The first laser beam spot LBS1 is preferably arranged on the downstream side of the second laser beam spot LBS2 in the transport direction T of the substrate to be processed 1. However, the amorphous silicon film is irradiated by the second laser beam spot LBS2. This is not the case as long as No. 5 melts at a high speed. Further, the shapes of the first laser beam spot LBS1 and the second laser beam spot LBS2 are arranged so that the first laser beam spot LBS1 passes through a part of the modified region, and the second laser beam spot LBS2 is formed in the modified region. Various shapes can be used as long as they can be formed so as to pass through the entire surface of the.

Although the DMD 18 is used in the above embodiment, the spatial light modulator includes a liquid crystal cell having an optical shutter function, a grating light valve (GLV: Grating Light Valve, a registered trademark of Silicon Light Machines, Inc.), and a thin film. It is also possible to use a micro mirror array (TMA: Thin-film Micro mirror Array) or the like. Further, although the spatial light modulator is used in the above embodiment, the first laser beam spot LBS1 may be simply formed by using a condenser lens, or the cylindrical lens is arranged so as to have a V-shape. It is also possible to form the second laser beam spot LBS2.

In the above embodiment, the pseudo single crystal silicon film 5B is formed as the crystallized silicon film, but it is of course possible to grow the polycrystalline silicon film from the seed crystal region. Also in this case, it is possible to form a high-quality polycrystalline silicon film starting from the seed crystal region.

LB laser beam T transport direction 1 substrate to be processed 2 glass substrate 3 gate wiring 4 gate insulating film 5 amorphous silicon film 5A seed crystal region 5B pseudo single crystal silicon film (modified region: crystallized silicon film)
5 GB grain boundary 10 laser annealing device 11 base 12A first laser light source unit 12B second laser light source unit 13 laser beam irradiation unit 14 control unit 15 second semiconductor laser 17 light emitting unit 18 digital micromirror device (DMD, spatial light modulation device) vessel)
19 Damper 20 Microlens Array 21 Projection Lens 22 Drive Substrate 23 Micromirror 25 First Semiconductor Laser 26 Light Emitting Section 27 Mirror 28 Mask

Claims

The substrate to be processed having the amorphous silicon film formed thereon is moved relative to the beam spot of the laser beam, and the amorphous silicon film is irradiated with the beam spot to form a crystallized silicon film. A laser annealing method for modifying,
The surface of the amorphous silicon film is irradiated with a first laser beam spot of a first laser beam in a wavelength range absorbed by the amorphous silicon to perform a first irradiation for melting the amorphous silicon. A seed crystal region forming step of forming a seed crystal region,
The second laser beam spot formed by the second laser light in the wavelength range absorbed by the melted silicon is changed to the first laser beam spot in the state where the first irradiation is performed on the seed crystal region to melt the silicon. A modified region forming step of performing second irradiation for irradiating a region adjacent to the seed crystal region, and growing crystallized silicon in a modified region continuous with the seed crystal region as a starting point;
A laser annealing method comprising:
The wavelength range of the first laser light is from near ultraviolet to visible light,
The laser annealing method according to claim 1, wherein a wavelength range of the second laser light is at least visible light.
The laser annealing method according to claim 1, wherein the first laser light and the second laser light are each oscillated from a semiconductor laser.
The laser annealing method according to any one of claims 1 to 3, wherein the power density of the first laser light is lower than the power density of the second laser light.
The laser annealing according to any one of claims 1 to 4, wherein the first laser beam spot is arranged at the same position or a downstream side in the transport direction of the substrate to be processed as compared with the second laser beam spot. Method.
The first laser beam spot is arranged so as to pass through a part of the modified region,
The laser annealing method according to any one of claims 1 to 5, wherein the second laser beam spot is formed so as to pass through the entire surface of the modified region.
The laser annealing method according to claim 5, wherein the plurality of second laser beam spots are formed so as to extend from the first laser beam spot.
The said 2nd laser beam spot is arrange|positioned so that it may extend toward the diagonally upstream side of the conveyance direction of the said to-be-processed substrate from the said 1st laser beam spot. Laser annealing method.
The amorphous silicon film is set to move relative to the beam spot of the laser beam on the substrate to be processed, and the amorphous silicon film is irradiated with the laser beam at the beam spot. A laser annealing apparatus for irradiating and modifying a crystallized silicon film,
A first light source unit that oscillates a first laser beam in a wavelength range absorbed by the amorphous silicon film;
A first light source section that oscillates a second laser beam in a wavelength range that is absorbed by the melted silicon;
Equipped with
The amorphous silicon film is melted by irradiating a first laser beam spot made of the first laser beam, and a second laser beam spot made of the second laser beam is formed on the silicon melted by the first laser beam. A laser annealing device for irradiating a region adjacent to the first laser beam spot.
The wavelength range of the first laser light is from near ultraviolet to visible light,
The laser annealing apparatus according to claim 9, wherein the wavelength range of the second laser light is visible light or more.
The laser annealing device according to claim 9 or 10, wherein the first laser light and the second laser light are emitted from a semiconductor laser, respectively.
The laser annealing apparatus according to any one of claims 9 to 11, wherein the power density of the first laser light is set lower than the power density of the second laser light.
The said 1st laser beam spot is arrange|positioned rather than the said 2nd laser beam spot at the same position in the conveyance direction of the said to-be-processed substrate, or a downstream side. Laser annealing equipment.
The first laser beam spot is arranged so as to pass through a part of the modified region,
The laser annealing apparatus according to any one of claims 9 to 13, wherein the second laser beam spot is formed so as to pass through the entire surface of the modified region.
The laser annealing apparatus according to claim 13 or 14, wherein a plurality of the second laser beam spots are formed so as to extend from the first laser beam spot.
The said 2nd laser beam spot is arrange|positioned so that it may extend toward the diagonally upstream side of the conveyance direction of the said to-be-processed substrate from the said 1st laser beam spot. Laser annealing equipment.