JPH10294289A - Laser annealing device and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately control laser irradiation so that the amorphous thin film of silicon and the like is processed with a right condition at the time of annealing and crystallizing it. SOLUTION: An orientation meter 19 measures the crystal orientation property of a crystallized thin film 9a and it is judged whether the irradiation energy of laser light 22 irradiated by a judgement means 20 is over or not. An adjusting device 21 adjusts the output of a laser irradiation device 12. Thus, it is judged whether the irradiation energy of laser light is over or not during inline. An operation condition (laser output) is immediately adjusted to appropriate one and the crystallized thin film can be manufactured with satisfactory yield.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser annealing apparatus for obtaining a crystal thin film used as a transparent electrode for an electronic display and other semiconductor materials, and a control method thereof.

[0002]

2. Description of the Related Art At present, inexpensive amorphous materials (such as amorphous silicon) are used for many transparent electrodes used for electronic displays such as liquid crystal displays, and the amorphous transparent electrodes are formed on a substrate such as glass. C
It is manufactured by forming a film by VD or the like. In recent years, there has been a strong demand for higher image quality in liquid crystal displays and the like, and a TFT system having relatively high image quality has been often used as a driving method. It is desired to adopt this.

As for this transparent electrode material, it is known that a crystalline thin film has a wider viewing angle and a higher transparency than an amorphous thin film. It is advantageous. As a method of obtaining the crystalline thin film, there is a method of forming a crystalline thin film by forming a film at a high temperature. However, since the manufacturing cost is increased, generally, once an amorphous thin film is formed by CVD, etc. Has been adopted.

[0004] As a method of crystallizing an amorphous thin film, a method of heating the entire amorphous thin film formed on the substrate together with the substrate to 1000 ° C. or more in an electric furnace or the like to crystallize the amorphous thin film together with the substrate.
There is known a laser annealing method of heating to about 00 ° C. and irradiating a laser beam such as an excimer laser to an amorphous thin film to polycrystallize an irradiated portion. However, the former method of the above methods has a drawback that the substrate is also heated to a high temperature, so that the substrate must be made of high heat resistance and therefore expensive quartz glass or the like must be used.
On the other hand, since the laser annealing method can be processed at a relatively low temperature, the restriction on the selection of the substrate is small, and therefore, it is attracting attention as an inexpensive manufacturing method that can use inexpensive alkali glass or the like. However, in this method, since the amorphous phase is crystallized by short-time laser light irradiation, the irradiation energy density of the laser light greatly affects the quality of the crystallized thin film. That is, if the irradiation energy density is low, crystallization is not sufficiently performed, and if the irradiation energy density is too high, there occurs a problem that the crystal quality becomes uneven. Therefore, conventionally, a method of observing whether or not the laser output during annealing is appropriate and performing operation control while constantly monitoring is adopted.

[0005]

However, in the above-described laser annealing apparatus, the optical system through which the laser beam is transmitted prevents contamination by evaporation of impurities from the thin film and adhesion of NH ₃ ions and SO ₂ ions floating in the air. As a result, the transmittance of the laser light decreases with time, so that the laser beam irradiation energy density in the thin film fluctuates even if the laser output is kept constant. When the energy density of the laser beam is reduced as described above, the amorphous thin film cannot be sufficiently crystallized, and even if the energy density becomes excessive, good quality crystals cannot be obtained. If it is not appropriate, the product quality will be degraded, and the product quality will vary. In addition, the quality of the crystallized thin film, apart from visual defects, cannot usually be ascertained until the final product inspection. This causes a problem that the yield is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and the degree of crystallization of a thin film is ascertained during or immediately after annealing. An object of the present invention is to provide a laser annealing apparatus capable of obtaining a thinned film and a control method thereof.

[0007]

Means for Solving the Problems To solve the above problems, a first method of controlling a laser annealing apparatus according to the present invention is described.
The invention of the present invention is a method for controlling a laser annealing apparatus for irradiating a laser beam onto an amorphous thin film to polycrystallize the amorphous thin film, wherein the crystal orientation of the crystallized thin film is measured, and the amorphous thin film is determined from the measurement result. It is characterized in that it is determined whether the irradiation energy of the laser light applied to the laser beam is excessive or deficient, and the laser output is adjusted based on the determination result.

According to a second aspect of the invention, there is provided a method for controlling a laser annealing apparatus according to the first aspect, wherein the crystal orientation is measured during or after the laser annealing.

Further, a laser annealing apparatus according to a third invention is a laser annealing apparatus for irradiating a laser beam to an amorphous thin film to crystallize the amorphous thin film.
An orientation meter for measuring the crystal orientation of the crystallized thin film, a judging means for judging excess or deficiency of the irradiation energy of the laser light from the measurement result of the orientation meter, and a laser irradiation device based on the judgment result of the judging means And a laser output adjusting means for adjusting the output.

[0010] A laser annealing apparatus according to a fourth aspect of the present invention comprises the third aspect.
In the invention of the above, a laser annealing treatment chamber for irradiating a laser beam by arranging an amorphous thin film, an orientation measurement chamber provided with an orientation meter, which is continuous with the annealing treatment chamber, and an orientation measurement chamber from the laser annealing treatment chamber And a thin film moving means for moving the crystallized thin film.

The present invention can be used for manufacturing a transparent electrode used for a TFT type liquid crystal display as described above, and is suitable for an apparatus for changing an amorphous silicon thin film for a transparent electrode into a crystalline thin film (polysilicon). However, the present invention is not particularly limited in the material type and use of the thin film, and can be applied to any laser annealing apparatus for the purpose of crystallizing an amorphous thin film. The type of laser in the laser annealing apparatus is suitable for application to an excimer laser which is a high-density energy source. This is because, because of high-density energy irradiation, a change in the transmittance of the optical system largely appears as a change in irradiation energy density, so that the effect of the present invention is remarkably exhibited. Regardless of this, the type of the laser is not limited to the above-described excimer laser in the present invention.

The laser annealing apparatus usually has an annealing chamber whose atmosphere can be adjusted. For example, the pressure in the annealing chamber can be reduced, and nitrogen gas or the like can be introduced into the annealing chamber as an inert gas. Then, the thin film is crystallized (polysilicon) by irradiating a laser beam to the amorphous thin film arranged in the annealing chamber. The method of forming the amorphous thin film to be annealed and the type of the substrate are not particularly limited in the present invention.

The laser source is usually placed outside the annealing chamber, and the laser light output from the laser source is transmitted through an optical system such as a reflecting mirror, a homogenizer, and a transmission window provided in the processing chamber. After that, the amorphous thin film is irradiated.
As described above, these optical systems deteriorate with time and the transmittance gradually decreases.In addition, among the optical systems, a transmission window and a reflecting mirror disposed in the processing chamber are caused by evaporation from a thin film or the like. There is a problem that the glass is easily contaminated and the transmittance gradually decreases. Means for preventing contaminants from adhering to the transmission window or the like by disposing an adsorption member in the processing chamber has also been proposed, but the contamination has not yet been completely prevented, and the transmittance varies. The phenomenon has not been eliminated.

Next, the crystal orientation of the crystallized thin film is measured by
Although the measurement can be performed on the portion where the laser beam irradiation has been completed during the annealing, it is easier to perform the measurement after the annealing is completed. When the measurement is performed after annealing, the measurement can be performed after the crystallized thin film is taken out of the annealing processing chamber. It is desirable to do it before contact. This is because the surface of the crystallized thin film is contaminated when it is brought into contact with the outside air, so that cleaning or the like is required for accurate orientation measurement, which increases the work and labor. Further, it is desirable to provide a thin film moving device and an opening / closing door between the continuous annealing chamber and the measuring chamber. This is because the atmosphere of each chamber can be adjusted independently, and continuous processing of the substrate is enabled. Therefore, other thin films can be annealed while the orientation is being measured.
When the annealing chamber and the orientation measurement chamber are connected continuously,
Both may be connected directly, or may be connected indirectly through another space such as a cooling room or a discharge room. Anything that can be done is acceptable.

Next, as a method of measuring the orientation of the crystallized thin film, a molecular orientation meter used for measuring the orientation of a polymer film or the like can be used. Although the present invention is not particularly limited with respect to the principle, for example, there is a method of measuring a dielectric constant or a refractive index using microwave polarization and indicating the measured value as a numerical value or a measurement pattern.
The measurement results of the various orientation meters are compared with, for example, numerical values and patterns predetermined by a determination unit to determine whether the laser irradiation energy density is excessive or insufficient. For example, in the determination means, data such as numerical values and patterns that would be obtained when the laser irradiation energy density is appropriate or in excess or deficiency are stored in a memory in advance, and are called upon determination to call up actual measurement. The data is compared with the data, and the result of the comparison is transmitted as determination data indicating the state of the laser irradiation energy, such as shortage, appropriateness, or excessiveness, and the degree thereof based on the conformity, excess or deficiency, pattern similarity, and the like. The above determination result is desirably used as control data to the laser output adjusting device. The laser output can be adjusted by, for example, changing the current supplied to the laser output unit based on the determination, thereby maintaining the laser output or increasing or decreasing the laser output by a predetermined amount. The change in the laser output may be changed at once for the thin film to be annealed, or may be changed stepwise or gradually during the annealing, and the form of the change is not particularly limited.

As described above, the orientation of a crystallized thin film is measured and used for control because the crystal grows in a specific direction when the amorphous film is crystallized. Because there is a phenomenon that indicates the direction,
The present inventor has learned the causal relationship between the orientation of an annealed crystallized thin film and the laser irradiation energy, and has found for the first time that this can be used for controlling a laser annealing apparatus, leading to the present invention. In other words, if the laser light irradiation energy density is insufficient, crystallization is not performed sufficiently, so that the thin film does not show sufficient directionality, and if an excessive laser light irradiation energy density is applied, the crystallinity becomes irregular. In other words, the performance as a semiconductor is significantly reduced. Therefore, by measuring the crystal orientation of the crystallized thin film, it is possible to know whether the laser beam irradiation energy density during annealing is excessive or insufficient. By adjusting the output of the laser light according to the degree of the excess or deficiency, it is possible to obtain the desired crystallization by irradiating the amorphous thin film with the laser light at an appropriate energy density regardless of the fluctuation of the transmittance of the optical system. it can.

[0017]

Next, an embodiment of the present invention will be described with reference to the accompanying drawings. The laser annealing apparatus 1
A vacuum chamber 2 made of aluminum is provided. The vacuum chamber 2 is divided into a sample introduction preparation chamber 2a, an annealing chamber 2b, and a sample unloading chamber 2c by gate valves 3, 4, and each of the chambers 2a to 2c. 2c, a vacuum exhaust port and a nitrogen gas supply port (not shown) are respectively provided on the walls.
Is formed, and the indoor atmosphere can be adjusted to a vacuum atmosphere or an inert gas atmosphere. A gate valve 5 for sample introduction is provided in the sample introduction preparation chamber 2a, and a gate valve 6 is provided in the preparation chamber 2a.
The preheating chambers 7a and 7b are connected via a and 6b.

On the other hand, a movable mounting table 8 is disposed in the annealing chamber 2b, and a film forming substrate made of soda lime glass and having an amorphous silicon film formed on the surface is provided on the movable mounting table 8. 9 are arranged. A laser introduction window 11 made of a quartz glass plate is provided at the ceiling of the annealing chamber 2b, and an optical path for introducing (deforming, deflecting, etc.) a laser beam outside the laser introduction window 11 is provided. The optical system includes a mirror 13 for deflecting the laser beam and a cylindrical lens 14 for condensing the laser beam in a linear manner.
An XeCl excimer laser irradiating device 12 that outputs laser light toward 3 is arranged.

The sample discharge chamber 2c is provided with a sample discharge gate valve 15. The sample discharge chamber 2c is further provided with a cooling chamber 17, an orientation measurement chamber via gate valves 16a and 16b. 18 are connected. In the sample unloading chamber 2c, there is provided a substrate moving device 10 for moving the substrate 9 in the annealing processing chamber 2b to the sample unloading chamber 2c and further moving the substrate 9 to the cooling chamber 17, the orientation measurement chamber 18 or the outside of the sample unloading chamber 2c. Are located. On the other hand, the orientation measurement chamber 18
Inside, a dielectric constant measuring device using microwave polarization is arranged as an orientation meter 19, and the output of the orientation meter 19 is:
The output of the determination device 20 is input to the laser light output control device 21. The laser light output controller 21 changes the value of the current supplied to the laser light irradiation device 12. Note that the determination device 20
Is a memory 20a for storing predetermined reference data.
And comparison unit 20b for comparing reference data and measurement data
And a determination data creation unit 20c that creates and sends the determination data based on the comparison result. The comparison unit 20b and the determination data creation unit 20c can be configured by one CPU.

Next, a processing procedure using the above laser annealing apparatus will be described. First, a film forming substrate 9 in which an amorphous silicon thin film is formed on a substrate made of soda glass by CVD or the like is prepared, the gate valve 5 is opened, and the film forming substrate 9 is loaded into the sample introduction preparation chamber 2a. The gate valve 5 is closed, and the inside of the vacuum chamber 2 is adjusted to a vacuum atmosphere or an inert gas atmosphere by an exhaust port or a nitrogen gas supply. Next, the gate valve 6a is opened, the deposition substrate 9 is put into the heating chamber 7a, and after closing the gate valve 6a, the substrate 9 is heated to a predetermined temperature (about 400 ° C.). At this time, the film formation substrate for the next process is carried into the sample preparation chamber 2a, and the heating chamber 7b
Since it is also possible to heat the substrate, it is possible to continuously process a plurality of substrates by appropriately adjusting the opening / closing timing of each of the gate valves 5, 6a, 6b, and 3.

The film substrate 9 preheated as described above is moved to the moving mounting table 8 in the annealing chamber 2b by a moving device (not shown) while opening and closing the gate valves 6a and 3 to move the moving mounting table 8. Then, the film forming substrate 9 is arranged at the initial position. At this time, the gate valve 3 is closed. Next, the XeCl excimer laser irradiating device 12
A laser beam (ultraviolet light) 22 is generated from the laser beam, is deflected by a mirror 13, is condensed linearly by a cylindrical lens 14, and irradiates the surface of the film forming substrate 9 through the laser introduction window 11 almost vertically. In this state, the movable mounting table 8 is moved in a direction substantially perpendicular to the longitudinal direction of the laser beam 22, and the entire surface of the film forming substrate 9 is scanned by a laser irradiation portion having a small area. Is crystallized.

After the annealing is completed, the gate valve 4 is opened, and the crystallized film-forming substrate 9a crystallized by the annealing by the sample moving device 10 is taken out from the moving mounting table 8, and
The sample is unloaded to the sample unloading chamber 2c, and the gate valve 4 is closed. Next, the gate valve 16a is opened, and after moving to the cooling chamber 17, the gate valve 16a is closed to cool the crystallized film forming substrate 9a to a predetermined temperature. Cooled crystallization film forming substrate 9a
After the gate valve 16a is opened and moved to the sample unloading chamber 2c by the moving device 10, the gate valve 16b is opened and moved to the orientation measuring chamber 18, the gate valve 16b is closed, and the thin film is measured by the dielectric constant. Is measured. At this time, the dielectric constant distribution in the azimuth can be obtained by rotating the sample. The crystallization-formed substrate 9a whose orientation has been measured moves to the sample carrying-out chamber 2c with the gate valve 16b opened, and is carried out with the gate valve 15 opened. Note that the crystallization film forming substrate 9a is
While the orientation of the substrate is being measured, the next annealed substrate can be moved from the annealing chamber 2b to the sample unloading chamber 2c and the cooling chamber 17 and cooled, so that the gate valve 15 can be moved in the same manner as the loading side. , 16a, 16b, the substrate can be continuously moved to the unloading chamber, cooled, measured for orientation, and unloaded.

The result measured by the orientation meter 19 is as follows:
The data is sent to the comparison unit 20b of the determination device 20 and stored in the memory 2 in advance.
Compare with the reference data stored in 0a. In the orientation meter 19, the dielectric constant with respect to the azimuth is obtained.
In 0a, a dielectric constant distribution pattern in a case where crystallization is properly performed, a case where the crystallization is insufficient, a case where the crystallization is excessive, or the like is recorded. FIG. 2 shows an example, in which those having a large orientation have a flatter elliptical distribution, and those having no orientation have a circular distribution. The comparing unit 20b compares the similarity of the patterns of the actual measurement data based on the reference data, and sends the result to the determination data creating unit 20c. In the above comparison, for example, the degree of orientation can be indicated by the flatness of the dielectric constant distribution pattern. The determination data creation unit determines whether the laser beam irradiation energy density is appropriate or not, based on the comparison result, together with the degree thereof, and sends the determination data to the laser output adjustment unit 21. In the laser output adjusting unit 21, when the laser beam irradiation energy density is insufficient based on the determination data,
The output is increased by increasing the current introduced into the laser irradiation device 12 according to the degree of shortage, and if the laser beam irradiation energy density is excessive, the laser irradiation device 1 is controlled according to the degree of excess.
2 to reduce the output current by reducing the current.

In the above-described annealing apparatus, the adjustment of the laser output is applied to the substrate to be processed next or most recently, although the defect of the substrate that has already been annealed cannot be ameliorated.
It is possible to immediately change the operating conditions to continue the operation, and to reduce the reject rate to a small value (about 1 to 2 sheets) to produce a high-quality crystallized thin film with good yield. In a situation where the laser irradiation energy density exceeds the limit and becomes insufficient, it is also possible to instruct the determination device to replace or clean the optical system. In the above embodiment, a dielectric constant meter was described as an orientation meter. However, it goes without saying that the present invention is not limited to a specific orientation meter.

[0025]

As described above, according to the laser annealing apparatus and the control method thereof of the present invention, the crystal orientation of the crystallized thin film is measured, and the laser light applied to the amorphous film is measured based on the measurement result. The laser output can be adjusted based on the determination result by judging whether the irradiation energy is excessive or insufficient, so that the annealing can be immediately continued with the proper laser irradiation energy, and the product yield can be greatly improved. And variations in products can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention.

FIG. 2 is a graph showing an example of a dielectric constant distribution pattern based on orientation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser annealing processing apparatus 2 Vacuum chamber 2a Sample introduction preparation room 2b Annealing processing room 2c Sample unloading room 9 Film forming substrate 9a Crystallized film forming substrate 10 Substrate moving device 11 Laser introduction window 12 XeCl excimer laser irradiation device 13 Mirror 14 Cylindrical lens 18 Orientation measurement room 19 Orientation meter 20 Judgment device 21 Laser light output control device 20a Memory 20b Comparison unit 20c Judgment data creation unit 22 Laser light

Claims (4)

[Claims] 1. A method for controlling a laser annealing apparatus for irradiating a laser beam onto an amorphous thin film to polycrystallize the amorphous thin film, comprising measuring the crystal orientation of the crystallized thin film, and determining the amorphous orientation from the measurement result. A method for controlling a laser annealing apparatus, comprising: judging excess or deficiency of irradiation energy of a laser beam applied to a thin film, and adjusting a laser output based on the judgment result. 2. The method for controlling a laser annealing apparatus according to claim 1, wherein the measurement of the crystal orientation is performed during or after the laser annealing. 3. An orientation meter for measuring the crystal orientation of a crystallized thin film in a laser annealing apparatus for irradiating a laser beam to the amorphous thin film to polycrystallize the amorphous thin film, and obtaining a result of measurement by the orientation meter. A laser annealing apparatus comprising: a determination unit that determines whether the irradiation energy of laser light is excessive or deficient; and a laser output adjustment unit that adjusts an output of the laser irradiation device based on a determination result of the determination unit 4. A laser annealing processing chamber for irradiating a laser beam by arranging an amorphous thin film, an orientation measuring chamber provided with an orientation meter, which is continuous with the annealing processing chamber, and an orientation measuring chamber provided from the laser annealing processing chamber. 4. The laser annealing apparatus according to claim 3, further comprising a thin film moving means for moving the crystallized thin film into the measurement chamber.