JPH1116850A - Device and method for treating sample - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out uniform treatment at multiple points such as polycrystallization of an amorphous thin film, by irradiating multiple points on the surface of a sample with laser beam a given number of times. SOLUTION: The surface of a sample 4 is irradiated with laser beam in pulse form. The strength of oscillation is controlled in such a manner that the strength of the first oscillation is larger than the average of oscillation strength of the second oscillation and later. The first laser beam is likely to vary its oscillation strength because of its property. Since the oscillation is set higher than normal case, oscillation lower than the intended value can at least be prevented. The sample 4 which is treated by a first laser beam in a good condition can be finally treated in a condition at least better than the intended condition by second and later laser beam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample processing apparatus and method for processing a flat sample.

[0002]

2. Description of the Related Art Conventionally, as a typical technique for forming a thin film transistor (TFT) as a thin film transistor on the surface of a glass substrate, a hydrogenated amorphous semiconductor T
There are FT technology and polycrystalline silicon TFT technology.

In the former hydrogenated amorphous semiconductor TFT technology, the maximum temperature of the manufacturing process is about 300 ° C.
A carrier mobility of about 1 cm ² / Vsec is realized.
On the other hand, the latter polycrystalline silicon TFT technology uses, for example, an LSI (Large Scale Integrated) using a quartz substrate.
A carrier mobility of about 30 to 100 cm ² / Vsec is realized by executing a high-temperature process of about 1000 ° C. equivalent to that of the circuit.

The technology of such high carrier mobility is
For example, when applied to a liquid crystal display or the like, a switching TFT for individually driving a liquid crystal element and a driver circuit around the switching TFT can be formed on the same substrate at the same time, so that the number of manufacturing processes and the size of the device can be reduced. It becomes possible.

However, since the process temperature of the polycrystalline silicon TFT technology is extremely high similarly to the LSI process, it is difficult to use a glass substrate which is inexpensive but has a low softening point. In this regard, there is a demand for lowering the process temperature.

For example, in the method of manufacturing a semiconductor device disclosed in Japanese Patent Publication No. Hei 7-118443, a semiconductor thin film of silicon formed on the surface of a substrate is irradiated with a short-wavelength laser beam in a pulsed manner to thereby reduce the temperature of the substrate. Heats a semiconductor silicon thin film while maintaining it at a low temperature to cause polycrystallization. For this reason, it is possible to manufacture a semiconductor having good characteristics on the surface of an inexpensive glass substrate, and to manufacture a large-area, high-performance liquid crystal display.

However, as disclosed in the above-mentioned publication, in order to crystallize a semiconductor silicon thin film with a short-wavelength laser beam, an oscillation intensity of about 50 to 500 mJ / cm ² is required. On the other hand, the light emission intensity of a current general laser light source is about 1 J / pulse, and when simply calculated, the area that can be irradiated at one time is only about ² to ²⁰ cm ² .

Therefore, if the entire surface of a substrate having a size of 47 × 37 cm is crystallized, at least 8
It is necessary to irradiate 7 to 870 points with a laser beam.
A conventional example of an apparatus for realizing such processing will be described below with reference to FIG. The drawing is a schematic view showing the structure of the sample processing apparatus.

In the sample processing apparatus 1 exemplified here, a glass substrate 3 on which a semiconductor silicon thin film 2 is laminated becomes a flat sample 4, and an xy stage 5 is provided as a sample holding mechanism for holding the sample. I have. The xy stage 5 is supported, for example, by guide rails (not shown) so as to be movable in XY directions corresponding to front, rear, left and right, and is relatively moved by an actuator or a control circuit for moving the xy stage 5 in these directions. A mechanism (not shown) is formed.

A laser irradiator 8 is opposed to the surface of the glass substrate 3 held by the xy stage 5 via a plurality of deflection mirrors 6 and a beam homogenizer 7. The laser irradiator 8 includes an imaging optical system and a laser light source, and a driver circuit (not shown) for emitting a laser beam in a pulse shape is connected to the laser light source.
The beam homogenizer 7 is an optical element that generates predetermined optical characteristics, and makes the spatial intensity of the transmitted laser beam uniform.

A sample cassette 9 containing a large number of samples 4 is arranged on the side of the xy stage 5. The sample cassette 9 stored in the sample cassette 9 and the sample cassette 9 are held on the surface of the xy stage 5. A sample transport mechanism 10 for exchanging the sample 4 is provided by an actuator or the like.

In the sample processing apparatus 1 having the above-described structure, the surface of the sample 4 is irradiated with a laser beam emitted from the laser irradiator 8 in a pulse shape, and the sample 4 is sequentially moved in the XY directions by the xy stage 5. You. As a result, the entire surface of the sample 4 is irradiated with the laser beam, so that the silicon thin film 2 of the semiconductor is polycrystallized without deterioration of the glass substrate 3. In the sample processing apparatus 1 described above, one sample 4
When the surface treatment is completed, the sample transport mechanism 10
The sample 4 held on the surface of the stage 5 is
Is exchanged with the sample 4 stored in the storage unit, so that many samples 4 are processed in order.

In the case where a large number of semiconductor elements are manufactured by polycrystallizing a large-area silicon thin film 2 on the surface of a glass substrate 3 by the sample processing apparatus 1 as described above, Japanese Patent Application Laid-Open No.
As disclosed in JP-A-2111167, a large number of elements can be manufactured uniformly by dividing an element block into a smaller size than a laser beam and repeating irradiation of several pulses and movement of an irradiation area by step & repeat. be able to. That is, as shown in FIG. 11, the position of the element block of the semiconductor silicon thin film 2 on the surface of the glass substrate 3 is uniformly polycrystallized by alternately performing the oscillation of the laser beam and the movement of the sample 4. be able to.

[0014]

The sample processing apparatus 1 as described above uniformly processes a large-area thin film 2 by irradiating a plurality of portions of the surface of a sample 4 with a laser beam in a pulsed manner a predetermined number of times. It is possible to

However, since the current laser irradiator 8 has a uniform oscillation intensity of about ± 5% (during continuous pulse oscillation), for example, a laser beam of 3 to 20 pulses In this case, it is difficult to uniformly polycrystallize a large number of element blocks because the oscillation intensity error for each pulse is accumulated.

In particular, when the sample 4 is processed by irradiating a laser beam, the intensity of the first pulse laser beam has a great influence. However, the discharge of the laser beam at the initial stage of oscillation is unstable, and as a result, unevenness of oscillation intensity called spiking occurs remarkably.

In order to cope with this, for example, in order to equalize the cumulative intensity when a laser beam is repeatedly emitted to one place of the sample 4, the oscillation intensity of the laser irradiator 8 is integrated every predetermined number of times. A method of controlling the applied voltage at the time of the next-stage oscillation has been proposed.

However, in this case, the cumulative intensity of the laser beam repeatedly irradiated to one location of the sample 4 can be made uniform. However, as shown in FIG. 11, the non-oscillation time longer than the oscillation cycle of the laser beam is obtained. If present, the first oscillation intensity at the start of oscillation cannot be made uniform.

For example, as shown in FIG. 12, when the irradiation time of the laser beam and the moving time of the sample 4 are alternately continuous, the oscillation intensity of the first pulse of a plurality of laser oscillations repeated in one irradiation time is increased. Most unstable and easy to fluctuate. However, when the sample 4 is processed by irradiating the laser beam as described above, the intensity of the laser beam of the first pulse greatly affects. In addition, since the cumulative intensity of the laser beam differs depending on the irradiation position of the sample 4, the polycrystallization of the silicon thin film 2 on the surface of the sample 4 is not uniformly performed, and the performance of a TFT manufactured using the same is also uniform. Does not.

To solve the above-mentioned problem, FIG.
As shown in (1), there has been proposed a method in which oscillation of a laser beam is started from the outside of a region where an element is formed, and irradiation is performed on a required portion of the sample 4 after oscillation intensity of the laser beam is stabilized. As described above, it is difficult when the moving time of the sample 4 is longer than the oscillation cycle of the laser beam.

Therefore, Japanese Patent Application Laid-Open No. Hei 5-90191 discloses that a laser beam is continuously oscillated in a pulsed manner as shown in FIG. An approach is disclosed. However, in this case, it is necessary to oscillate a laser beam that does not process the thin film 2 in the process 4, so that power consumption increases unnecessarily and the life of the laser light source decreases, and a dedicated mechanism for shielding the laser beam is also provided. The necessity complicates the structure of the device.

The present invention has been made in view of the above-mentioned problems, and has as its object to provide a sample processing apparatus and method capable of uniformly processing the surface of a large-area sample.

[0023]

According to the present invention, there is provided a sample processing apparatus comprising: a sample holding mechanism for holding a flat sample; a laser irradiator for irradiating a surface of the held sample with a pulsed laser beam; An intensity control device that controls the laser beam that the laser irradiator repeatedly irradiates to one position of the sample in a pulse shape so that the first oscillation intensity is larger than the average value of the second and subsequent oscillation intensity. .

Therefore, when the laser irradiator irradiates the surface of the sample held by the sample holding mechanism with a laser beam in a pulsed manner, the laser irradiator repeatedly irradiates a portion of the sample with a pulsed laser beam. The intensity control device controls the first oscillation intensity to be greater than the average value of the second and subsequent oscillation intensity.

For example, when a substrate on which a semiconductor thin film is laminated is a sample, and the semiconductor thin film is polycrystallized by pulsed irradiation of a laser beam, the intensity of the laser beam increases within a predetermined range. The crystal grain size is also increased. However, when a laser beam having a larger intensity than that range is applied, the semiconductor thin film becomes amorphous and the crystal grain size is reduced. However, when the sample in such a state is repeatedly irradiated with a low-intensity laser beam, the crystal grain size increases with the number of times.

As described above, by controlling the laser beam that repeatedly irradiates one portion of the sample in a pulse shape so that the first oscillation intensity is larger than the average value of the second and subsequent oscillation intensity, the first laser beam can be obtained. If the oscillation intensity of the sample is sufficiently larger than a predetermined range, the semiconductor thin film of the sample becomes amorphous, and if the oscillation intensity is larger than the predetermined value, it can be tolerated. Since the oscillation intensity of the second and subsequent laser beams is relatively stable, if the number of times is limited, the thin film layer is polycrystallized to a desired crystal grain size.

The intensity control device referred to in the present invention only needs to be formed so as to realize its functions. For example, dedicated hardware, a computer provided with appropriate functions by a program, a computer provided by an appropriate program , The functions realized inside, and the combination thereof are allowed.

According to another aspect of the above-described sample processing apparatus, a laser irradiator includes a laser light source whose emission intensity changes in response to an applied voltage and a driver circuit which generates a variable voltage. When the laser irradiator repeatedly irradiates a laser beam to one portion of the sample in a pulsed manner, the voltage generated by the driver circuit for the first oscillation is higher than the voltage after the second. Control so that

Accordingly, when the laser light source repeatedly irradiates the laser beam to one portion of the sample with a pulse generated by the driver circuit variably, the first oscillation voltage becomes higher than the second and subsequent voltages. As described above, since the intensity control device controls the driver circuit, the first oscillation intensity of the laser beam repeatedly irradiated to one portion of the sample in a pulse shape is larger than the average value of the second and subsequent oscillation intensity.

The laser light source referred to in the present invention may be any laser light source as long as its oscillation intensity changes according to the applied voltage. I do.

In another aspect of the above-described sample processing apparatus, the sample comprises a substrate in which a semiconductor thin film is laminated on an insulator, and the strength control device converts the semiconductor thin film of the sample into an amorphous material. The first laser beam is controlled to the oscillation intensity to be controlled, and the second and subsequent laser beams are controlled to the oscillation intensity at which the crystal grain size of the thin film of the amorphized sample is enlarged.

Accordingly, the semiconductor laser thin film on the surface of the sample is made amorphous by the first laser beam, and the crystal grain size of the amorphous thin film of the sample is enlarged by the second and subsequent laser beams. The sample thin film is polycrystallized to have a desired particle size.

According to the sample processing method of the present invention, a flat plate-shaped sample is held, a laser beam is irradiated in a pulsed manner on the surface of the held sample, and a laser beam is repeatedly irradiated in one place on the sample. The second oscillation intensity is controlled so as to be larger than the average value of the second and subsequent oscillation intensity.

Therefore, when a substrate on which a semiconductor thin film is laminated on the surface is a sample and the semiconductor thin film is polycrystallized by pulsed irradiation of a laser beam, the intensity of the laser beam increases within a predetermined range. The crystal grain size is also increased. However, when a laser beam having a larger intensity than that range is applied, the semiconductor thin film becomes amorphous and the crystal grain size is reduced. However, when the sample in such a state is repeatedly irradiated with a low-intensity laser beam, the crystal grain size increases with the number of times.

As described above, if the laser beam that repeatedly irradiates one position of the sample in a pulse shape is controlled so that the first oscillation intensity is larger than the average value of the second and subsequent oscillation intensity, the first laser beam can be obtained. If the oscillation intensity of the sample is sufficiently larger than a predetermined range, the semiconductor thin film of the sample becomes amorphous, and if the oscillation intensity is larger than the predetermined value, it can be tolerated. Since the oscillation intensity of the second and subsequent laser beams is relatively stable, if the number of times is limited, the thin film layer is polycrystallized to a desired crystal grain size.

As another invention in the above-described sample processing method, a sample includes a substrate in which a semiconductor thin film is laminated on an insulator, and has an oscillation intensity that makes the semiconductor thin film of a sample amorphous. The second laser beam is controlled so as to control the oscillation intensity at which the crystal grain size of the thin film of the amorphized sample expands by controlling the first laser beam.

Accordingly, the first laser beam amorphizes the semiconductor thin film on the surface of the sample, and the second and subsequent laser beams enlarge the crystal grain size of the amorphized thin film of the sample. The sample thin film is polycrystallized to have a desired particle size.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. Note that the same portions as those of the conventional example described above with respect to the present embodiment are denoted by the same names, and detailed description is omitted.

FIG. 1 is a schematic diagram showing a sample processing apparatus according to the present embodiment, FIG. 2 is a time chart showing a voltage applied to a laser light source by a driver circuit of a laser irradiator, and FIG. 4 is a flowchart showing a sample processing method using a sample processing apparatus, and FIGS. 5 to 7 are observations of a silicon thin film irradiated with laser beams of various intensities by a scanning electron microscope. FIG. 8 is a characteristic diagram showing a change in crystal grain size of a silicon thin film due to repeated irradiation of a laser beam, and FIG. 9 is a time chart showing an oscillation intensity of a laser beam irradiated on a sample by a laser irradiator of a modified example. It is.

Also in the sample processing apparatus 21 of the present embodiment, the glass substrate 3 on which the semiconductor silicon thin film 2 is laminated
Is a sample 4 in the form of a plate, and has an xy stage 22 as a sample holding mechanism for holding the sample 4 and a relative moving mechanism. A laser irradiator 25 is opposed to the surface of the glass substrate 3 held by the xy stage 22 via a plurality of deflecting mirrors 23 and a beam homogenizer 24. The laser irradiator 25 includes an imaging optical system. And a laser light source and a driver circuit (not shown).

The laser light source is composed of an XeCl excimer laser, and the oscillation intensity changes according to the voltage applied to the driver circuit. More specifically, an excimer laser performs preionization by UV (Ultra Violet ray).
s) An arc ray and a main discharge electrode are provided, which are connected to a high voltage power supply via a thyratron as a switching element and an excitation circuit (not shown).

A sample cassette 26 containing a large number of samples 4 is arranged on the side of the xy stage 22, and the sample 4 stored in the sample cassette 26 and the x
A sample transport mechanism 27 for exchanging the sample 4 held on the surface of the y stage 22 is provided by an actuator or the like.

Then, the sample processing apparatus 21 of the present embodiment
In the embodiment, a central control device 28 is connected to a laser light source of the laser irradiator 25, a drive source of the xy stage 22, and a drive source of the sample transport mechanism 27. And the xy stage 22
And the operation of the sample transport mechanism 27 are controlled.

More specifically, the central control unit 28
An appropriate program is formed of a microcomputer implemented as software, and the microcomputer executes various processing operations in accordance with the program, thereby realizing various functions as various means.

That is, the central control unit 28 controls the operation of the laser irradiator 25 and the xy stage 22 so that the laser irradiator 25 repeatedly irradiates the laser beam to one portion of the sample 4 in a pulsed manner. , The x
The y stage 22 relatively sequentially moves the sample 4 each time the laser irradiator 25 emits a pulsed laser beam up to a predetermined number of times.

At this time, the central control unit 28
As shown in (1), the voltage generated by the driver circuit of the laser irradiator 25 for the first oscillation is controlled to be higher than the voltage after the second. In other words, as shown in FIG. 3, the laser irradiator 25 repeatedly irradiates a portion of the sample 4 with a laser beam. The oscillation intensity is controlled so that the crystal grain size of the amorphous thin film 2 increases.

More specifically, in the sample processing apparatus 21 of the present embodiment, the number of laser beams emitted from the laser irradiator 25 to one location of the sample 4 is set to six, and the oscillation frequency is set to six. At 10 Hz, the moving time is 1.0 sec. The applied voltage for laser oscillation is set to 28.0 kV for the first and 27.4 kV for the second and later, so that the first oscillation intensity Ea is approximately 1.05 of the average value Eave of the second and subsequent oscillation intensity. It is doubled.

The central control unit 28 controls the operation of the laser irradiator 25 and the sample transport mechanism xy stage 22 so that the laser irradiator 25 stops emitting the laser beam repeated in a pulsed manner. The sample transport mechanism 27 exchanges the sample 4 held on the xy stage 22 with the sample 4 stored in the sample cassette 26.

More specifically, the central control unit 28
As described above, when the laser irradiator 25 repeatedly irradiates the laser beam to one position of the sample 4 up to a predetermined number of times, when the entire area of the surface of the sample 4 is completed, the sample transfer mechanism 27 replaces the sample 4. Is executed. The time required for the xy stage 22 to move the sample 4 and the time required for the sample transport mechanism 27 to exchange the sample 4 are longer than the oscillation cycle of the laser beam of the laser irradiator 25.

A sample processing method using the sample processing apparatus 21 of the present embodiment in the above-described configuration will be described below. First, also in the present embodiment, the sample 4 includes the glass substrate 3 on which the semiconductor silicon thin film 2 is laminated on the surface, and the sample processing method by the sample processing apparatus 21 is executed as the polycrystalline silicon thin film 2.

In this case, similarly to the conventional sample processing apparatus 1, an element block divided into a smaller size than the laser beam is set in the sample 4, and a predetermined number of times of irradiation and movement of the irradiation area are performed by step & repeat. Are repeated, and the positions of a number of element blocks of the semiconductor silicon thin film 2 on the surface of the glass substrate 3 are polycrystallized.

More specifically, in the sample processing method using the sample processing apparatus 21 of the present embodiment, as shown in FIG. 4, a high voltage is first set and laser oscillation is executed only once.
(Steps S1 and S2) Since the low voltage is set and laser oscillation is repeated up to a predetermined number of times (steps S3 to S2).
7), a laser beam having an oscillation intensity Ea is firstly irradiated to the element block at one position of the sample 4 and then a laser beam having an average value of the oscillation intensity Eave is repeatedly irradiated up to a predetermined number of times after the second. You.

When the laser irradiation as described above is completed, the sample 4 is moved together with the xy stage 22 until the processing is completed in the entire area (steps S8 and S9). The sample 4 is exchanged (Steps S10, S11).

In the sample processing method by the sample processing apparatus 21 of the present embodiment, when the laser irradiator 25 repeatedly irradiates the laser beam to the spot on the surface of the sample 4 a predetermined number of times as described above, As shown in FIG. 3, the oscillation intensity Ea of the first laser beam, which has the greatest effect on the amorphization of the silicon thin film 2, is set to be larger than 1.03 times the average value Eave of the oscillation intensity of the second and subsequent laser beams. , A large number of portions of the silicon thin film 2 are uniformly polycrystallized.

The principle will be described below. First, a silicon thin film 2 is formed on the surface of a glass substrate 3 to a thickness of 75 nm, and the laser irradiator 25 has an oscillation intensity uniformity of 3%.
A XeCl excimer laser having a wavelength of 308 nm was prepared.

Therefore, this laser beam was supplied at 339 mJ /
When the sample 4 was irradiated only once with an intensity of cm ² , as shown in FIG. 5, the silicon thin film 2 was polycrystallized so that the average crystal grain size was about 20 nm. FIG. 3 is a photograph obtained by applying anisotropic etching to the polycrystalline silicon thin film 2 with respect to the crystal orientation of Secco etching and observing the same with a scanning electron microscope.

When the oscillation intensity of the laser beam in the separate sample 4 was set to 424 mJ / cm ² , as shown in FIG. 6, the polycrystalline grain size of the silicon thin film 2 became about 70 nm on average, and the oscillation of the laser beam When the strength was 470 mJ / cm ² , as shown in FIG. 7, the polycrystalline grain size of the silicon thin film 2 was about 10 nm on average.

When each of the three types of samples 4 polycrystallized as described above was irradiated with a nine-pulse laser beam, the first oscillation intensity was 470, as shown in FIG.
The crystal grain size of sample 4 of mJ / cm ² was significantly increased. When the oscillation intensity after the second was 400 mJ / cm ² or less, there was no significant change in any of Samples 4 and 450 mJ / cm ^2.
A remarkable change was confirmed by setting the degree.

That is, by setting the first oscillation intensity of the laser beam to 470 mJ / cm ² and the second and subsequent oscillation intensity to 450 mJ / cm ² on average, the semiconductor silicon thin film 2 is made amorphous. From this, the crystal grain size was sequentially enlarged to obtain a desired state.

As a result, the silicon thin film 2 was polycrystallized to a desired grain size. When a large number of portions of the silicon thin film 2 were polycrystallized by this method, the average grain size was 5%.
The occurrence rate of the portion having a size of 0 nm or less was 3%, and the uniformity of polycrystallization was able to be improved to approximately ten times the conventional 30%.

In the sample processing method using the sample processing apparatus 21 according to the present embodiment, as described above, the first oscillation intensity of the laser beam repeatedly irradiated to one position of the sample 4 is calculated from the average value of the second and subsequent oscillation intensity. By being large, a large number of portions of the semiconductor silicon thin film 2 of the sample 4 can be uniformly polycrystallized.

That is, since the first oscillation intensity is higher than the normal oscillation intensity, even if the first oscillation intensity fluctuates, the polycrystallization of the silicon thin film 2 does not deteriorate from an expected state, and the low intensity laser beam Is repeatedly irradiated, so that the silicon thin film 2 is polycrystallized at least better than expected.

In particular, since the above-described laser beam intensity control is performed by the applied voltage, the laser beam can be easily controlled to a desired oscillation intensity. The first laser beam is controlled to the oscillation intensity for amorphizing the silicon thin film 2, and the second and subsequent laser beams are controlled to the oscillation intensity for expanding the crystal grain size of the amorphized silicon thin film 2. Therefore, the silicon thin film 2 polycrystallized to a desired particle size can be easily obtained, and a high-performance thin film transistor can be manufactured.

Further, the sample processing apparatus 21 of the present embodiment
In this case, the sample 4 is sequentially moved each time the processing of one place is completed, so that the entire surface of the sample 4 can be processed. At this time, the time required for the relative movement of the sample 4 is longer than the oscillation cycle of the laser beam, so that the oscillation intensity of the first laser beam fluctuates. Silicon thin film 2
Is polycrystallized in a good state.

Further, in the sample processing apparatus 21 of the present embodiment, since the samples 4 which have been completely processed are exchanged, a large number of samples 4 can be automatically processed. At this time, the time required for exchanging the sample 4 is also longer than the oscillation cycle of the laser beam, so that the oscillation intensity of the first laser beam fluctuates. Is thinly polycrystallized in a good state.

The present invention is not limited to the above-described embodiment, but allows various modifications without departing from the gist of the present invention. For example, in the embodiment described above, the semiconductor thin film 2 is polycrystallized by the sample processing method of the sample processing apparatus 21, but the polycrystalline thin film is recrystallized by the sample processing method of the sample processing apparatus of the present invention. It is also possible to let them.

In the above embodiment, the laser beam is applied to the sample 4
The method of moving only the sample 4 by the xy stage 5 has been exemplified as a method of relatively moving the portion irradiated with the laser beam. For example, the optical system such as the laser irradiator 8 and the deflection mirror 6 is moved while the sample 4 is fixed. Or both the optical system and the sample 4 can be moved.

Further, the use of an XeCl excimer laser as the laser light source of the laser irradiator 8 has been exemplified.
It is also possible to use a G laser. In addition, although the example has been described in which the oscillation intensity of the excimer laser is simply controlled by the applied voltage, it can be controlled by the circulation speed of the gas.

That is, the excimer laser has a gas circulation mechanism, which is composed of a high-speed fan and a high-torque motor. In the excimer laser, when the laser is oscillated by the main discharge, a thermal and acoustic change occurs in the main discharge space, so that the next main discharge output decreases.

When the excimer laser oscillates continuously,
Since the oscillation intensity is specified by the gas circulation speed and the oscillation frequency, the first oscillation intensity at the time of discharge is increased by increasing the circulation speed during the non-oscillation period and efficiently exchanging the gas present in the main discharge space. It is possible.

For example, when the laser beam is repeatedly irradiated to one place of the sample 4 up to ten times, the oscillation frequency is set to 10H
z, the moving time is 1.0 sec, and the applied voltage is constant. As shown in FIG. 8, the gas circulation speed during the irradiation period is 5 m / sec, and the gas circulation speed during the moving time is 8 m / sec. Then, the first oscillation intensity could be made about 1.04 times the average value of the second and subsequent oscillation intensity.

Further, in the above-described embodiment, an example is described in which the oscillation intensity of the laser beam is simply controlled by installing an appropriate program as software in the central control device 28 composed of a microcomputer. Can be formed by dedicated hardware, and such hardware can be combined with a microcomputer.

The program for causing the microcomputer to execute the above-described control is FD (Floppy Disc) or C
D-ROM (Compact Disc-Lead Only Memory)
The information can be stored in an information storage medium that can be handled as a single unit. A program for causing the microcomputer to execute control so as to be greater than the average value of the oscillation intensity thereafter may be stored as software.

[0074]

Since the present invention is configured as described above, it has the following effects.

According to a first aspect of the present invention, there is provided a sample processing apparatus, comprising: a sample holding mechanism for holding a flat sample; a laser irradiator for irradiating a laser beam in a pulse shape onto a surface of the held sample; The apparatus has an intensity control device for controlling a laser beam that repeatedly irradiates one position of the sample in a pulse shape so that the first oscillation intensity is larger than the average value of the second and subsequent oscillation intensity. Although the first laser beam has the greatest effect on the processing of the sample, the oscillation intensity tends to fluctuate, but since this is set to a higher intensity than usual, it can be oscillated at least at an intensity lower than expected. Rather, a sample processed in a good condition by the first laser beam can be finally processed to a better condition than at least by the second and subsequent laser beams. By executing such processing in multiple locations of the sample, it is possible to uniformly process a large number of points of the sample.

According to a second aspect of the present invention, there is provided the sample processing apparatus according to the first aspect, wherein the laser irradiator has a laser light source whose emission intensity changes in response to an applied voltage and a driver which generates a variable voltage. A voltage generated by the driver circuit with respect to the first oscillation when the laser irradiator repeatedly irradiates a laser beam to one portion of the sample in a pulsed manner. By controlling the voltage so as to be higher than the voltage after the first, the oscillation intensity of the laser beam can be easily controlled.

The third aspect of the present invention is the first or second aspect.
The sample processing apparatus according to the above, wherein the sample comprises a substrate in which a semiconductor thin film is laminated on an insulator, and the intensity control device includes:
The first laser beam is controlled to the oscillation intensity that amorphizes the semiconductor thin film of the sample, and the second and subsequent laser beams are controlled to the oscillation intensity at which the crystal grain diameter of the thin film of the amorphized sample expands. Accordingly, the semiconductor thin film can be polycrystallized to have a desired particle size, which can contribute to the manufacture of a high-performance thin film transistor.

According to a fourth aspect of the present invention, there is provided a sample processing method, wherein a flat sample is held, a surface of the held sample is irradiated with a laser beam in a pulse shape, and one portion of the sample is repeatedly irradiated in a pulse shape. By controlling the laser beam so that the first oscillation intensity is greater than the average value of the second and subsequent oscillation intensity, the first laser beam oscillates even though it has the greatest effect on sample processing. The intensity is easy to fluctuate, but since this is set higher than usual,
A sample that has been processed in a good condition by the first laser beam without being oscillated at least at an intensity lower than expected can be finally processed to at least a better condition by the second and subsequent laser beams. So, for example,
By performing such processing on a large number of portions of the sample, it is possible to uniformly process the large number of portions of the sample.

According to a fifth aspect of the present invention, there is provided the sample processing method according to the fourth aspect, wherein the sample comprises a substrate in which a semiconductor thin film is laminated on an insulator, and the sample semiconductor thin film is made amorphous. Control the first laser beam to the oscillation intensity to be
By controlling the second and subsequent laser beams to the oscillation intensity at which the crystal grain size of the amorphous thin film expands, the semiconductor thin film can be polycrystallized to a desired grain size. , And contribute to the production of high-performance thin film transistors.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a sample processing apparatus according to an embodiment of the present invention.

FIG. 2 is a time chart showing a voltage applied to a laser light source by a driver circuit of the laser irradiator.

FIG. 3 is a time chart showing the oscillation intensity of a laser beam irradiating a sample with a laser irradiator.

FIG. 4 is a flowchart illustrating a data processing method by the sample processing apparatus.

FIG. 5 is a photograph replacing a drawing in which a silicon thin film irradiated with a low-intensity laser beam is observed with a scanning electron microscope.

FIG. 6 is a photograph replacing a drawing obtained by observing a silicon thin film irradiated with a medium-intensity laser beam with a scanning electron microscope.

FIG. 7 is a photograph replacing a drawing in which a silicon thin film irradiated with a high-intensity laser beam is observed with a scanning electron microscope.

FIG. 8 is a characteristic diagram showing a change in crystal grain size of a silicon thin film due to repeated irradiation of a laser beam.

FIG. 9 is a time chart showing the oscillation intensity of a laser beam that irradiates a sample with a laser irradiator according to a modification.

FIG. 10 is a schematic diagram showing a sample processing apparatus of a conventional example.

FIG. 11 is a time chart showing the oscillation intensity of a laser beam that irradiates a sample with a conventional laser irradiator.

FIG. 12 is a time chart showing the relationship between laser oscillation and sample movement in the first conventional example.

FIG. 13 is a time chart showing the relationship between laser oscillation and sample movement in the second conventional example.

FIG. 14 is a time chart showing the relationship between laser oscillation and sample movement in a third conventional example.

[Explanation of symbols]

2 Thin film 3 Substrate 4 Sample 21 Sample processing device 22 xy which is a sample holding mechanism and a relative movement mechanism
Stage 25 Laser irradiator 27 Sample transfer mechanism as sample exchange mechanism 28 Central controller as intensity controller

Claims (5)

[Claims] A sample holding mechanism for holding a flat sample; a laser irradiator for irradiating the surface of the held sample with a laser beam in a pulse form; A sample processing apparatus, comprising: an intensity control device that controls a laser beam to be repeatedly irradiated so that the first oscillation intensity is larger than the average value of the second and subsequent oscillation intensity. 2. A laser irradiator comprising: a laser light source whose emission intensity changes in response to an applied voltage; and a driver circuit which generates a variable voltage. When a laser beam is repeatedly irradiated on a portion of the sample in a pulse shape, the voltage generated by the driver circuit for the first oscillation is controlled to be higher than the voltage after the second oscillation. 2. The sample processing apparatus according to 1. 3. The sample comprises a substrate in which a semiconductor thin film is laminated on an insulator. The intensity control device controls a first laser beam to an oscillation intensity for amorphizing the semiconductor thin film of the sample. And controlling the second and subsequent laser beams to the oscillation intensity at which the crystal grain size of the thin film of the amorphized sample expands.
Or the sample processing apparatus according to 2. 4. A flat sample is held, a surface of the held sample is irradiated with a laser beam in a pulsed manner, and a laser beam repeatedly irradiated on one portion of the sample is irradiated with a laser beam having a first oscillation intensity of two. A sample processing method characterized in that control is performed so as to be larger than the average value of the oscillation intensity after the first time. 5. A sample comprises a substrate in which a semiconductor thin film is laminated on an insulator, and controls a first laser beam at an oscillation intensity for amorphizing the semiconductor thin film of the sample to form the sample. 5. The sample processing method according to claim 4, wherein the second and subsequent laser beams are controlled to the oscillation intensity at which the crystal grain size of the thin film of the sample expands.