JPH11283933A - Laser beam irradiating device, manufacture of non-single crystal semiconductor film, and manufacture of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser beam irradiating device which is constituted to set the intensity of laser beam irradiating an object to be treated with high accuracy. SOLUTION: A laser beam irradiating device with which an object 19 to be treated is irradiated with the laser beam, by controlling the intensity of the laser beam is provided with a laser oscillator 1, homogenizers 7 and 11 which make the intensity distribution of the laser beam outputted from the oscillator 1 uniform, a condenser lens 15 which converges the laser beam shaped through a slit 16 that shapes the laser beam, the intensity of which is made uniform by means of the homogenizers 7 and 11 into the form of a prescribed beam by removing the part of the laser beam and projects the converged shaped laser beam upon the object 19, a detector 23 which detects the intensity of the laser beam passed through the slit 16 and made incident to the detector 23, and a controller 25 which controls the intensity of the laser beam, based on the detecting signal of the detector 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser irradiation apparatus for irradiating an object with a laser beam, a method for manufacturing a non-single-crystal semiconductor film using the same, and a method for manufacturing a liquid crystal display.

[0002]

2. Description of the Related Art When a semiconductor device or a liquid crystal display device is manufactured, light irradiation is required for a photolithography process and an annealing process. In these processes, a thin film process using a laser beam is performed. For example, in the annealing step, an amorphous semiconductor film as a non-single-crystal semiconductor film is irradiated with a laser beam from an excimer laser oscillator to perform an annealing treatment, thereby performing polycrystallization. In the photolithography process, when transferring a mask image to a photoresist on a semiconductor substrate, the mask image is transferred by a laser beam irradiation process from a laser oscillator.

[0003] A laser irradiation apparatus for performing processing using such a laser beam has a laser oscillator. The laser beam output from the laser oscillator has an intensity distribution substantially through an optical system including optical elements such as a homogenizer. In addition to being made uniform and being shaped into a predetermined beam irradiation surface, the beam is guided to an object to be processed, and the object to be processed is irradiated.

In such a process using a laser beam, in order to increase the accuracy of the process, the intensity of the laser beam for irradiating the object to be processed must be controlled with high precision. Conventionally, when managing the intensity of a laser beam, a part of the laser beam output from a laser oscillator is divided by a dividing unit such as a partial reflecting mirror, and the light intensity of the divided laser beam is detected. By doing that. The light intensity of the laser light output from the laser oscillator is controlled based on the detected value.

However, the laser light output from the laser oscillator is split by a splitting means such as a half mirror, and then passes through a homogenizer for making the intensity distribution almost uniform, a slit for shaping the beam shape, and the like. Irradiate the processed object. For this reason, the intensity of the laser beam split by the splitting unit and the intensity of the laser beam on the irradiation surface that actually irradiates the object to be processed cause a variation. Therefore, the control of the light intensity of the laser beam irradiating the object to be processed cannot be performed with high accuracy, which may adversely affect the accuracy of the processing by the laser beam irradiation.

In order to detect the intensity of the laser beam,
When splitting the laser light output from the laser oscillator,
The split laser light immediately enters the detector and its light intensity is detected. However, as described above, the laser light that irradiates the object to be processed passes through an optical system including a plurality of optical elements such as a homogenizer and a condenser lens, and reaches the object to be processed.

[0007] Therefore, the laser light irradiating the object to be processed absorbs the optical energy by these optical elements and the like, so that the optical loss of the optical energy in the optical path to the object to be processed in the optical system is reduced. Occurs. On the other hand,
The laser light directly detected by the detector without passing through the plurality of optical elements constituting the optical system after being split by the splitting means almost always causes optical loss of light energy in the plurality of optical elements. Absent.

Therefore, a difference occurs between the intensity of the laser beam detected by the detector and the intensity of the laser beam irradiating the object to be processed, and the output from the laser oscillator is determined based on the intensity of the laser beam detected by the detector. Even if the intensity of the laser light to be processed is controlled, the light intensity on the irradiation surface of the laser light for irradiating the object to be processed cannot be set to a predetermined value with high accuracy.

In recent years, in order to shorten the processing time of thermal annealing and improve production efficiency (throughput),
A laser beam in the ultraviolet wavelength range, such as an excimer laser, is applied as a linear irradiation surface (line beam) on an amorphous silicon film as a semiconductor film formed on a glass substrate as a thin film. The excimer laser annealing (FIG. 16) forms a semiconductor film having a high electron mobility described below by changing the amorphous silicon film to a non-single-crystal silicon film typified by a polycrystalline silicon film by irradiating as shown in FIG. ELA (Excimer Laser Anneal) technology has been developed. According to this process, since the amorphous silicon film is instantaneously melted and crystallized, the non-single-crystal silicon film can be formed by a low-temperature process of about 450 ° C. or less, which causes less heat damage to the substrate. Therefore, there is an advantage that a non-single-crystal silicon film can be formed using a large-area and inexpensive glass substrate, which is inferior in heat resistance.

Here, the magnitude of the electron mobility is μ = | v
_d / E | (cm ² / S · V), and the average moving speed (drift speed: v) of electrons in the crystal when an electric field E (V / cm) is applied to the crystal. _d (cm / s)) per unit electric field magnitude. In addition, non-single-crystal silicon includes a state in which a phase transition from amorphous silicon to polycrystalline silicon is in progress. This is because the amorphous silicon to be annealed by the laser beam is high purity, but the amorphous silicon ratio is not limited to 100%. This is because the non-single-crystal silicon film to be obtained can be obtained if the ratio of amorphous silicon decreases after annealing with laser light and can approach polycrystalline silicon.

By using such a non-single-crystal silicon film, a thin film transistor (TFT: Thin Film Transistor) having a high electron mobility on a glass substrate in the low-temperature process described above.
mTransistor). According to this non-single-crystal silicon TFT, the above problem is solved, and a driver monolithic type using an active matrix substrate in which a driving unit TFT (complementary transistor) and a pixel unit TFT are formed on a glass substrate is used. It is possible to obtain a thin, high-definition liquid crystal display device called a so-called liquid crystal display device. Here, as shown in FIG. 17 showing an LCD unit formed on a glass substrate, the driving unit TFT is controlled by a gate line (scanning line) and a data line (signal line) to apply a voltage to the liquid crystal. Display an image.

The gates and the data lines are controlled by a driver TFT composed of a gate driver and a source driver. The video signal and the synchronization signal from the signal control unit and the power from the power supply unit are input to each driver. The gate driver is one frame (60H
Once in z), this is a digital circuit having a function of selecting each gate line, and operates in a cycle of a scanning time (15 to 40 μsec). The source driver is a transparent I / O on the array substrate.
A voltage is applied to the gate line to the liquid crystal filled between the pixel electrode made of a TO (Indium Tin Oxide) film and the opposing pixel electrode on the opposing substrate, and a voltage corresponding to the video information is passed through the pixel TFT. It is a circuit to apply. The display of the liquid crystal is deteriorated if the DC voltage is continuously applied. Therefore, the liquid crystal is subjected to AC driving called inversion driving in which a voltage of opposite polarity is alternately applied to the opposite transparent electrode. The driving frequency of the source driver is 20 to 10
It becomes a high frequency such as 0 MHz. Therefore, it is necessary to increase the electron mobility of the driver TFT that requires high-frequency operation. However, in this case, it is necessary to accurately control the light intensity of the irradiated laser beam to increase the accuracy of the annealing treatment, thereby obtaining non-single-crystal silicon having good characteristics.

[0013]

As described above, when controlling the light intensity of a laser beam for irradiating an object to be processed, conventionally, a laser beam for detecting the light intensity and a laser beam for irradiating the object to be processed are conventionally used. In some cases, there is a difference in the intensity of the laser light and the irradiation accuracy of the laser light having an appropriate light intensity on the object to be processed. For this reason, there is a problem that it is not possible to irradiate a laser beam having an appropriate light intensity to the object to be processed, and it is not possible to perform highly accurate processing.

According to the present invention, the object to be processed is irradiated by minimizing the difference in light intensity between the laser light for detecting the light intensity and the laser light for irradiating the object to be processed. It is an object of the present invention to provide a laser irradiation apparatus capable of setting a light intensity of a laser beam with high accuracy and performing favorable processing.

Further, the present invention provides a method for manufacturing a non-single-crystal semiconductor film having high electron mobility using the above-described laser irradiation apparatus, and a method for manufacturing a liquid crystal display device exhibiting good operation characteristics using the semiconductor film. Is to do.

[0016]

According to a first aspect of the present invention, there is provided a laser irradiation apparatus for controlling a light intensity of a laser beam to irradiate an object to be processed with a laser oscillator and a laser beam output from the laser oscillator. Intensity uniforming means for forming a portion where the intensity distribution is substantially uniformed; forming means for removing a part of the laser light passing through the intensity uniformizing means to form a predetermined beam shape; Focusing optical means for converging the shaped laser light to irradiate the object to be processed; detecting means for detecting the intensity of the laser light removed by the forming means; and laser light based on a detection signal from the detecting means. And control means for controlling the intensity of the light.

According to a second aspect of the present invention, in the first aspect of the invention, the laser beam incident on the shaping means has a rectangular beam shape having a long part and a short part, and the shaping means has the intensity. The method is characterized in that both ends in the longitudinal direction of the beam shape including a portion where the intensity is made uniform by the uniforming means are removed.

According to a third aspect of the present invention, in the first aspect of the present invention, the detecting means includes a reflecting mirror for reflecting the laser light removed by the shaping means in a predetermined direction, and a laser light reflected by the reflecting mirror. It is characterized by having a detector for incidence, and a slit provided between the detector and the reflection mirror for removing a part of laser light incident on the detector.

According to a fourth aspect of the present invention, there is provided a laser irradiation apparatus for irradiating an object to be processed by controlling the intensity of a laser beam, and a laser oscillator and an intensity for making the intensity distribution of the laser beam output from the laser oscillator uniform. Homogenizing means, condensing optical means for converging the laser light homogenized by the intensity homogenizing means and irradiating the object with the laser light, and division for dividing a part of the laser light output from the laser oscillator Means, detecting means for detecting the intensity of the laser light split by the splitting means, control means for controlling the intensity of the laser light based on a detection signal from the detecting means, and between the splitting means and the detecting means. The optical loss substantially equivalent to the optical loss given to the laser light for irradiating the object to be processed is provided to the laser light divided by the dividing means and detected by the detecting means. Characterized by comprising the equivalent optical means for providing to.

A fifth aspect of the present invention is characterized in that, in the fourth aspect of the invention, the equivalent optical means is an optical means having the same configuration as the intensity equalizing means and the condensing optical means.

According to a sixth aspect of the present invention, the amorphous semiconductor film formed on the substrate is irradiated with laser light through a plurality of optical elements for each shot, and the laser light is emitted relative to the substrate. A method of manufacturing a non-single-crystal semiconductor film, comprising: a step of scanning by a predetermined distance; and a step of non-single-crystallizing the amorphous semiconductor film by irradiation with the laser light. The step of collecting the laser light that has passed through the optical element closest to the amorphous semiconductor film most optically of the optical element, and controlling the energy of the laser light. I do.

According to a seventh aspect of the invention, an amorphous semiconductor film formed on a substrate is irradiated with laser light through a plurality of optical elements for each shot, and the laser light is emitted relative to the substrate. A method of manufacturing a non-single-crystal semiconductor film, comprising: a step of scanning by a predetermined distance; and a step of polycrystallizing the amorphous semiconductor film by irradiation with the laser light, wherein the amorphous semiconductor film is polycrystallized. The step is a ratio of (the area integral of the first pulse in one pulse of the laser light × the energy at the irradiation part of the laser light) to (the area integral of one pulse of the laser light) or (the laser (Peak value of first pulse in one pulse of light × energy at irradiation part of laser light) and (peak value of first pulse in one pulse of laser light + second peak in one pulse of laser light) Of the pulse The laser light is irradiated with a ratio of (peak value + peak value of a third pulse in one pulse of the laser light) constant.

According to an eighth aspect of the present invention, a laser beam is applied to the amorphous semiconductor film formed on the first substrate through a plurality of optical elements for each shot, and the laser beam is applied to the first substrate. A step of irradiating the amorphous semiconductor film by non-single-crystallizing by irradiating the laser beam with the laser light, and a step of forming a thin film transistor group including a gate electrode line and a source electrode line. Forming on the first substrate using the non-single-crystallized amorphous semiconductor film; and forming the first substrate and the second substrate in a state where liquid crystal is interposed between the first substrate and the second substrate. And a step of encapsulating the substrate. 2. The step of non-single-crystallizing the amorphous semiconductor film, wherein the amorphous semiconductor film is the most optically Passed through an optical element close to Were taken laser light, characterized by having a step of controlling the energy of the laser beam.

According to a ninth aspect of the present invention, a laser beam is applied to the amorphous semiconductor film formed on the first substrate through a plurality of optical elements for each shot, and the laser beam is applied to the first substrate. A step of irradiating the amorphous semiconductor film by non-single-crystallizing by irradiating the laser beam with the laser light, and a step of forming a thin film transistor group including a gate electrode line and a source electrode line. Forming on the first substrate using the non-single-crystallized amorphous semiconductor film; and forming the first substrate and the second substrate in a state where liquid crystal is interposed between the first substrate and the second substrate. In the method of manufacturing a liquid crystal display device having a step of encapsulating the second substrate.
The ratio of the area integral value of the first pulse in the pulse × the energy at the irradiation part of the laser light) to (the area integral value of the one pulse of the laser light) or (the first pulse in one pulse of the laser light) The peak value of the laser beam irradiation energy) and (the peak value of the first pulse in one pulse of the laser beam + the peak value of the second pulse in one pulse of the laser beam + the laser beam) (The peak value of the third pulse in one pulse) is irradiated with the laser light.

According to the first aspect of the present invention, the intensity of the laser beam immediately before irradiating the object formed into a predetermined beam shape by the shaping means is detected, and the intensity of the laser beam is controlled by the detection signal. Therefore, the intensity of the laser light for irradiating the object can be set with high accuracy, and the intensity of the laser light is detected by using the unnecessary laser light removed by the molding means. The intensity can be detected without wasting the laser light used for the laser beam.

According to the second aspect of the present invention, the laser light removed by the shaping means detected by the detecting means is included in the laser light to be removed by the shaping means, because the laser light includes a portion whose intensity is made uniform by the equalizing means. And the intensity of the laser light irradiating the object to be processed are less likely to be different.

According to the third aspect of the present invention, when detecting the laser beam removed by the shaping means, a part of the laser beam is removed by the slit so as to be incident on the detector. A portion of the intensity distribution having low uniformity can be removed, and the detection accuracy by this detector can be improved.

According to the fourth and fifth aspects of the present invention, when measuring the intensity by dividing a part of the laser light output from the laser oscillator, the laser light to be measured is generated by absorption by the optical element or the like. Since the optical loss is set to be the same as the optical loss received by the laser beam irradiating the workpiece,
The intensity of the laser light for irradiating the object to be processed can be accurately controlled.

According to the sixth aspect of the present invention, the intensity of the laser beam immediately before irradiating the object shaped into a predetermined beam shape is detected, and the intensity of the laser beam is controlled by the detection signal. The intensity of laser light for irradiating a processed object can be set with high accuracy, and a high-quality non-single-crystal semiconductor film with high electron mobility can be obtained.

According to the seventh aspect of the present invention, the output waveform of the laser light itself changes due to deterioration of the gas laser medium or the like, so that even if the beam quality such as the beam shape and the divergence angle changes, the annealing process can be performed successfully. Accordingly, a high-quality non-single-crystal semiconductor film with high electron mobility can be obtained.

According to the eighth aspect of the present invention, the intensity of the laser beam immediately before irradiating the object shaped into a predetermined beam shape is detected, and the intensity of the laser beam is controlled by the detection signal. The intensity of laser light for irradiating a processed object can be set with high accuracy, and a liquid crystal display device using a high-quality non-single-crystal semiconductor with high electron mobility can be obtained.

According to the ninth aspect of the present invention, even if the output quality of the laser beam itself changes due to deterioration of the gas laser medium or the like, the annealing process can be performed successfully even if the beam quality such as the beam shape and the divergence angle changes. Accordingly, a liquid crystal display device using a high-quality non-single-crystal semiconductor film with high electron mobility can be obtained.

[0033]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show a first embodiment of the present invention.
The laser irradiation apparatus shown in FIG. The laser oscillator 1 is, for example, a XeCl excimer laser, and a laser beam L having a rectangular beam shape output as a pulse from the laser oscillator 1 is reflected by a first reflection mirror 2 and is incident on a variable attenuator 3. The laser beam L whose intensity has been adjusted by the variable attenuator 3 is incident on the second reflecting mirror 5 after the optical path is corrected by the compensating center 4.

The laser light L reflected by the second reflecting mirror 5 enters a telescope 6. This telescope 6
Is composed of a first lens 6a and a second lens 6b having different focal lengths and having the same focal position, and the laser beam L incident on the first lens 6a has an enlarged beam diameter. Then, the light is emitted from the second lens 6b as a parallel light beam.

The laser light L emitted from the telescope 6 is made substantially uniform in the light intensity distribution in the long axis direction by the long axis homogenizer 7, and then the long axis imaging lens 8 constituting the long axis homogenizer 7 is formed. , An image is formed in the long axis direction. The long axis homogenizer 7 is configured by disposing a pair of long axis cylindrical lens arrays 9 at predetermined intervals.

The laser light L emitted from the long-axis imaging lens 8 is applied to the short-axis homogenizer 1 in which a pair of short-axis cylindrical lens arrays 10 are arranged at predetermined intervals.
After the light intensity distribution in the short-axis direction is made substantially uniform at 1, the short-axis direction is imaged by the first short-axis imaging lens 12 constituting the short-axis homogenizer 11, and the short-axis field lens is formed. 13 is incident.

That is, the laser beam L output from the laser oscillator 1 is transmitted to the long axis homogenizer 7, the short axis homogenizer 11, the long axis imaging lens 8 and the first short axis imaging lens 12. As shown in FIG. 3A, the beam shape is formed into a rectangular shape having a long part and a short part, and the light intensity distribution excludes both ends in the longitudinal direction of the beam shape as shown in FIG. 3B. The portion is almost uniformed to the light intensity indicated by energy A.

The laser beam L emitted from the short-axis imaging field lens 13 is reflected by the third reflecting mirror 14 and is
The first slit 16 constituting the shaping means while being imaged by the short-axis imaging lens 15 has a predetermined shape. In this embodiment, both ends in the longitudinal direction are part of the above-described elongated rectangular beam shape. After being removed, the light enters a processing chamber 17 where annealing is performed. Specifically, both ends where the light intensity distribution indicated by E in FIG. 3B gradually decreases, that is, both ends E (edges) slightly including a portion of energy A where the light intensity distribution is uniformized Part) is the first slit 16
And enters the processing chamber 17. This portion E is not used for irradiating the object to be processed (glass substrate) 19. That is, it is not used for annealing.

The processing chamber 17 has a transmission window 17a into which the laser light L enters, and the laser light L imaged by the second short-axis imaging lens 15 passes through the transmission window 17a and is placed on the mounting table 18 The object to be processed 19 placed thereon is irradiated.

As shown in FIGS. 1 and 2, an amorphous silicon film 19a to be annealed by a laser beam L is uniformly formed on the upper surface of the object 19. In other words, CVD (Chemical Vapor Depositi
On) and the like, an undercoat and an amorphous semiconductor film are uniformly formed on the object to be processed 19 to a predetermined thickness. Note that an amorphous silicon film having a thickness of 50 nm to 100 nm is used as the amorphous semiconductor film, and a thickness of 0.35 μm to
0.40 μm SiO _x , SiN _x or TEOS (Te
tra Ethyl Ortho Silicate: Si [OC ₂ H ₅ ] ₄ ) is formed as an undercoat.

The first slit 16 is formed so that the longitudinal dimension of the laser beam L having an elongated rectangular beam shape is formed to the same length as the width of the amorphous silicon film 19a. That is, the second slit 22
When the amorphous silicon film 19a is irradiated and annealed, an unnecessary portion (a portion E) of the laser beam L that does not contribute to the annealing is removed.

As shown in FIG. 2, a portion of the laser beam L on one end side in the longitudinal direction, which is removed by the first slit 16, ie, an optical path of the removed laser beam R, is provided with the removed laser beam R in a predetermined direction. A fourth reflection mirror 21 that reflects light from the light source is disposed. The removed laser light R reflected by the fourth reflection mirror 21 is formed by the second slit 22 and is incident on a detector 23 (energy monitor) that detects light intensity.

The second slit 22 has a function of removing a part of the removed laser light. That is, FIG.
In the light intensity distribution in the width direction of the removed laser light R shown in (a), both end portions in the width direction having low degrees of intensity distribution (corresponding to both end portions in the width direction of the elongated rectangular beam) are removed, and FIG. Detector 2
3 Thereby, the detection accuracy of the light intensity of the removed laser light R by the detector 23 can be improved.

The intensity signal of the removed laser light R detected by the detector 23 is input to the control device 25 via the energy monitor 24. The control device 25 can set the required light intensity of the laser beam L in accordance with the type of processing of the processing object 19. The control device 25 sets the set value set here and the detector 23. Is compared with the detected light intensity of the removed laser light R.

If there is a difference between the comparison results, a drive signal corresponding to the difference is output to each of the drive units 26a and 26b for driving the variable attenuator 3 and the compensing center 4. As a result, the intensity of the laser beam L passing through the variable attenuator 3 is corrected to be equal to the set value, and the optical path of the laser beam L transmitted through the variable attenuator 3 by the compensating center 4 is shifted from the original optical path. It is corrected so that there is no.

The processing of the detection signal detected by the detector 23 in the control device 25 is performed as follows. That is, the removed laser light R removed by the first slit 22
Is detected as a waveform whose energy is integrated by the detector 23. By holding the peak value of this waveform, the analog data is processed as digital data.

The basic performance of the detector 23 is such that the average energy value of the detector 23 is linear with respect to the transmittance of the variable attenuator 3. If linearity cannot be obtained, curve approximation may be performed on the laser waveform.

Normally, since linearity is obtained, the following equation (1) is satisfied. E = a · T + b (1) where E: energy value, T: transmittance of the variable attenuator 3, and a, b: coefficients.

Even when the energy equation expressed by the following equation (2) changes to E ₂ as shown in the following equation (3) at the start of the laser annealing, the transmittance of the variable attenuator 3 is always adjusted to the energy of E _1. Change. E ₁ = a · T ₁ + b Equation (2) E ₂ = a · T ₁ + b Equation (3)

The energy increase / decrease rate is calculated by canceling the coefficient b, and the transmittance T ₂ to be fed back is calculated from the following equation (4) using the equation (1). T ₂ = [E ₁ ｛(E ₁ -b) / (E ₂ -b)｝-b] / a (4)

Based on the result of the above equation (4), the variable attenuator 3 is driven to have a transmittance of T ₂ . Thereby, the laser light L transmitted through the variable attenuator 3
Can be controlled to be constant.

According to the laser irradiation apparatus having the above structure, the intensity of the laser beam L is detected immediately before the laser beam L enters the processing chamber 17. That is, the detector 23 detects the light intensity of the removed laser light R generated by the first slit 16 being formed just before the laser light L enters the processing chamber 17.

The laser beam L for irradiating the object 19 and the removal laser beam R whose light intensity is detected by the detector 23 pass through substantially the same optical path. Therefore, these laser beams L and R also have substantially the same optical loss due to the plurality of optical elements in the optical path, and thus have substantially the same light intensity. Therefore, the light intensity of the laser light L that irradiates the workpiece 19 can be detected with high accuracy from the light intensity of the removal laser light R.

Therefore, based on the detection signal from the detector 23, the transmittance of the variable attenuator 3 (the laser beam L
Is controlled, for example, the laser oscillator 1
Even if the intensity of the laser light L output from the controller changes with time, the light intensity of the laser light L for irradiating the processing object 19 is substantially equal to the set value set in the control device 25. Can be controlled.

The detector 23 detects the light intensity of the removed laser light R removed by the first slit 16. The first slit 16 is an object 19 to be processed by the laser light L.
When the entire width of the amorphous silicon film 19a is irradiated, unnecessary portions protruding from both ends in the width direction are removed. Therefore, even when detecting the light intensity of the laser light L, the laser light L used for processing the workpiece 19 is not wastefully consumed.

Moreover, the removed laser beam R split by the first slit 16 includes a portion where the light intensity distribution at the longitudinal end of the elongated rectangular beam is substantially uniform. Therefore, since the light intensity of the removed laser light R is substantially the same as the light intensity of the laser light L irradiating the processing target 19, the light intensity of the laser light L can be controlled with high accuracy by the detection signal.

Further, both ends of the removed laser light R having a low degree of uniformity of the light intensity distribution are removed by the second slit 22 in the removed laser light R incident on the detector 23. Therefore, the detection accuracy of the removed laser light R by the detector 23 is also improved, so that the light intensity of the laser light L can be controlled with high accuracy.

FIG. 5 is a diagram showing a schematic configuration of a laser irradiation apparatus according to a second embodiment of the present invention. 1 and 2 have the same configuration and operation unless otherwise specified. In FIG. 5, the molding optical system 27
Is to make the light intensity of the laser light L uniform and to mold it. The third reflection mirror 14 totally reflects the laser beam L in the case of FIG. 1, but transmits a part of the laser beam L in FIG. 5, and passes through the lens 28 the same laser waveform as in the first embodiment. Monitoring detector (energy monitor)
23. Further, a beam profiler 29 composed of a CCD for measuring the spatial intensity distribution of the laser light is provided. In this case, the detector 23 detects the laser light L
, And the beam profiler 29 has a separated configuration for measuring the removed laser beam R. However, in order to prevent optical loss due to the optical element as in the first embodiment,
Both may be configured to measure the removal laser light R.

Here, since the gas laser medium of the laser oscillator 1 is deteriorated, the gas laser medium may be replaced. Further, the transmission window 17a may be contaminated by the annealing process and need to be replaced. In such a case, the light intensity distribution of the laser beam L at the processing point on the workpiece 20 may change. It is considered that this is because the laser optical axis shifts when the gas laser medium is filled or the transmission window 17a is replaced. When the optical axis shifts in this way, as shown in FIG. 6, even if there is no change in the sum of the irradiation energies indicated by oblique lines, a change occurs in the peak value of the energy intensity indicated by I ₁ and I _2. Occurs, and proper annealing cannot be performed.

Therefore, as shown in FIG. 7, from the shape of the intensity distribution in the short-axis direction cross section (that is, the long axis direction) when the optical axis is at an appropriate position as measured by the beam profiler 29,
The point c, which is the center position of the intensity distribution, is calculated so that (ba) / 2 = c. Points a and b are the positions of the shoulders in this intensity distribution. Points at which the rate of change of the light intensity changes from a flat portion to a steepness portion where the rate of change decreases become point d and point e. Further, the points a ′, b ′, c ′, and d ′ are determined corresponding to the shape of the intensity distribution in the short-axis direction cross section when the optical axis is shifted accordingly.

Here, if any one of (c'-c), (d'-d) and (e'-e) deviates by a predetermined value (for example, 10 .mu.m), c'-c = 0. By driving the actuator 30 attached to the first reflection mirror 2, the shape of the intensity distribution in the short-axis direction cross section is adjusted to be optimal. If this deviation cannot be corrected even by driving the actuator 30, the annealing process is stopped because the laser oscillator 1 itself may be defective.

Further, as described above, it is necessary to exchange the gas laser medium, and at this time, the impedance of the discharge circuit of the gas laser oscillator 1 changes. Also,
Even when the gas laser medium deteriorates itself, the impedance of the discharge circuit changes. Therefore, the output waveform itself of the laser light L also changes, thereby changing the beam quality such as the beam shape and the divergence angle. Therefore, even if the energy of the processing point is measured and the output of the gas laser oscillator 1 is always kept constant, there is a problem that the annealing process cannot be performed well with the deterioration of the gas laser medium.

However, when the integrated value of the area of the laser output waveform is constant, there is a difference between the energy at the processing point and the first peak value of the output waveform when obtaining the target average crystal grain size. The inventor of the present application has confirmed that there is a linear relationship shown in FIG. A method of realizing accurate monitoring by using the phenomenon and obtaining a target average crystal grain size will be disclosed below.

As shown in FIG. 9 and FIG. 10, the first to third pulses are set for the mountains separated by broken lines,
The peak values of these pulses are defined as first to third peaks to define the pulses and peaks in the laser output waveform. Note that some output waveforms of the laser light L have two or three peaks as shown in these figures. Based on this shape, an optimum annealing process is performed.

The output waveform of the laser light L is measured by the detector 23, and the area integral value of each pulse, the area integral value of the entire output waveform, and each peak value are detected by using the beam profiler 29. Further, since the output of the gas laser oscillator 1 fluctuates somewhat every moment, the average value of the pulse energy measured at the processing point (preferably an average value for 5 or more pulses) is calculated. Based on these results, optimal annealing can be performed if the following two equations take constant values. However, when there are only two peaks in the equation (6), the third peak value is calculated as zero. (1st pulse area integrated value × average energy at processing point) / total area integrated value = constant (5) Equation (1st peak value × average energy at processing point) / (first peak value + second peak) Value + third peak value) = constant ... Equation (6)

The transmittance (angle with respect to the laser beam L) of the variable attenuator 3 is controlled so as to satisfy the above equation. However, as the annealing process proceeds, the amount of transmitted light in the entire optical system changes, and the area integral value and peak of energy are changed. Since the value changes, a constant value is taken as the integral value or peak value of the energy per unit. Further, this constant value varies depending on the conditions of the gas laser medium and the like, but it is desirable to suppress the variation within 5% from the constant value. If the variation is too large, the annealing process is stopped.

When the measurement is performed using only the light transmitted through the second short-axis imaging lens 15 from the results shown in FIG. 8, a variable attenuator is used so that the absolute value of the first peak value is constant. By controlling the transmittance of No. 3, a certain effect can be achieved.

By the way, the spatial light intensity distribution can be measured by the beam profiler 29, but the accuracy is low. The reason is that the calculation of the energy intensity I (mJ / cm ² ) at the processing point approximates this spatial light intensity distribution to a uniform trapezoid. In other words, half of the width (= W) or half of the half-value width (= w) of the 90% light intensity (= W) of the line beam in the short-axis direction cross section is taken as the center position of the line beam and the laser output P ( W) and the energy E (J), which is the laser output per laser repetition frequency f (Hz). That is, I =
E / L · W or I = E / (L · w). Here, L (cm) is the length of the cutout portion of the line beam. However, as shown in FIG. 6, even if the area integral value of the energy is constant, the peak value and the half width may be different due to distortion of the intensity distribution.

Therefore, in the present invention, the beam profiler 2
Α (cm) is the unit horizontal axis distance component which is the resolution at 9
Assuming that the unit vertical axis intensity component which is the resolution of the energy intensity measurement value component in the detector 23 is β (mJ / cm ² ), the area integral value Δ of the light intensity profile in the short-axis direction cross section is as shown in FIG. Δ, which is the total number of mesh divisions, is multiplied by the mesh area. Δ = δ ・ α ・ β ... Equation (7)

However, in the above equation, α and δ are known, but β is an unknown number, so it needs to be obtained. Therefore, based on the value of the energy directly measured by the detector 23, FIG.
The area S (J / cm) of the trapezoid indicated by 1 is given by the following equation. S = E / L Equation (8)

At this time, at an arbitrary measurement point in the second slit 22, taking into account the standard deviation σ of the energy stability of the laser oscillator 1, the light is statistically averaged so as to be smaller than the average value ξ%. Measure the intensity distribution. The number n of laser pulses for reducing the average value is given by the following equation. For example, if ξ is 2% and σ is 2.5%, n is 1
4 shots or more. n> (3σ / ξ) ² (9) The control device 25 calculates β from the respective Δ and S data. Thus, a unit height per unit horizontal axis distance component of the trapezoid in FIG. 11 is obtained. Therefore, an accurate trapezoidal shape can be obtained by superimposing and integrating α and β, so that an accurate energy integrated value and an accurate peak value can be obtained. The beam profiler 29
Can measure the point with the highest energy intensity for each pixel. Assuming that the number of the highest energy density is N, the transmittance of the optical system is given by the following equation as t (%). It · N = N · β (10) Here, the flow of the processing up to now is shown in the flowchart of FIG. First, the average energy per unit pulse from the laser oscillator 1 is measured to reduce the influence of energy fluctuation. From the measured value of the average energy, a correction coefficient is calculated in consideration of the difference between the measured energy intensity and the set energy intensity due to the attenuation in the optical system and the error in the laser oscillator 1.

The variable attenuator 3 may be driven based on the value of the correction coefficient, but the ELA processing is started thereafter. Then, data such as the energy intensity is measured for each pulse, and the average value and the variation of the energy intensity during the annealing process are newly obtained upon completion of one scan (scanning). These data are stored and used for quality control of the annealing process. If all the scans are completed, the process is finished. Otherwise, the pulse energy of the next scan is measured, and the same process is repeated until the end of the annealing process.

FIG. 13 is a view showing a schematic configuration of a laser irradiation apparatus according to the third embodiment of the present invention. The laser irradiation apparatus according to this embodiment has a laser oscillator 31 such as a XeCl excimer laser similar to that of the first embodiment.
It has. A beam splitter 32 is arranged at an angle of 45 degrees in the optical path of the laser light L output from the laser oscillator 31 so as to split a part of the laser light L.

The laser beam L that has passed through the beam splitter 32 has its beam diameter expanded by the first telescope 33a, and the first homogenizer 33 makes the light intensity distribution in the major axis direction and the minor axis direction substantially uniform. You.

Next, the laser beam L is reflected by the reflection mirror 34a.
After being reflected by the first condensing lens 34, the light is converged by the first condenser lens 34 and enters the inside of the processing chamber 35 through the transmission window 36. Inside the processing chamber 35, similarly to the first embodiment, an object to be processed 38 made of a glass substrate for a liquid crystal on which an amorphous silicon film is formed is mounted on a mounting table 37. The silicon film is irradiated with the laser light L and annealed.

The split laser beam R ′ split by the beam splitter 32 passes through the equivalent optical means 41 and passes through the detector 42.
The light intensity is detected. The equivalent optical means 41 is composed of the same optical elements as a plurality of optical elements disposed between the beam splitter 32 and the processing chamber 35. That is, between the beam splitter 32 and the detector 42, the second telescope 43, the second homogenizer 44, and the second condenser lens 45 are arranged.

Therefore, the object 38 to be processed is placed in the processing chamber 35.
The optical loss due to absorption of an optical element and the like from the transmission of the laser beam L for irradiating the beam splitter 32 to the irradiation of the workpiece 38 and the split laser beam R split by the beam splitter 32 are detected by a detector. The optical loss due to absorption of the optical element and the like before the detection at 42 is substantially equivalent.

When the detector 42 detects the light intensity of the divided laser light R ', the detection signal is input to the control device 46. A set value corresponding to the type of processing of the workpiece 38 is set in the control device 46, and the control device 46 compares the detected value with the set value.

If there is a difference between the comparison results, the high-voltage power supply 47 for supplying excitation energy to the laser oscillator 31 is controlled based on the difference. Thus, the intensity of the laser light L output from the laser oscillator 31 is controlled so as to be equal to the set value set in the control device 46.

According to the laser irradiation apparatus having such a configuration, the laser beam R ′ split by the beam splitter 32 and detected by the detector 42 passes through the beam splitter 32 and passes through the optical path of the processing chamber 35. An equivalent optical means 41 having an optical loss substantially equivalent to the optical loss received by the laser light L irradiating the processing object 38 is provided.

Therefore, in order to detect the intensity of the laser beam L, the optical loss received by the laser beam L output from the laser oscillator 31 and transmitted through the beam splitter 32 to irradiate the object to be processed 38 and the beam splitter 32 Since the optical loss received by the divided laser light R ′ detected by the detector 42 after being reflected by the laser beam 42 becomes substantially equivalent, the light intensity of the divided laser light R ′ and the laser light L irradiating the workpiece 38 are The light intensity is almost the same.

Therefore, even if the light intensity of the divided laser light R 'is detected and the light intensity of the laser light L is controlled based on the detection result, the light intensity of the laser light L can be set with high accuracy. Can be.

Now, by using the above-described method for manufacturing a non-single-crystal silicon film, which is embodied by these laser irradiation apparatuses, the non-single-crystal A method for manufacturing a driver monolithic liquid crystal display device made of silicon will be described as a fourth embodiment of the present invention. FIG. 14 shows a cross section of the liquid crystal display device 81. In addition, a spacer, a color filter, a light shielding film, a polarizing plate, and the like are not shown. The glass substrate 80 of the liquid crystal display device 81
On a, a coplanar thin film transistor as a semiconductor device is formed through a normal PEP (Photo Engraving Process) process or the like. That is, a P-type TFT 82, an N-type TFT 83, and a pixel TFT 84 are formed. P type T
The FT 82 and the N-type TFT 83 form a driving unit 85 and are complementary transistors (CMOS). The pixel TFT 84 forms a pixel matrix section (display section) 86.

Each of the TFTs 82 to 84 is formed in a predetermined shape on a non-single-crystal silicon film (hereinafter, referred to as a polysilicon film) 87 having a crystallized portion by the above-described annealing method on the amorphous silicon film. Is formed on the undercoat 80b.
In the polysilicon film 87, a channel region 87a serving as a passage through which electrons flow, and a source region 87b and a drain region 87c doped with impurities (donor / acceptor) such as P (phosphorus) and B (boron) are formed. ing.

The polysilicon film 87 is formed of a gate insulating film 88
Covered by A gate electrode 89 is formed on the gate insulating film 88, and the gate electrode 89 is covered with an interlayer insulating film 91. A contact hole is provided in the interlayer insulating film 91, and a source electrode 92a connected to the source region 87b and a drain electrode 92b connected to the drain region 87c are formed through the contact hole. Further, a source electrode line (signal line) 93a is connected to the pixel TFT 84 via a source electrode 92a, and ITO (Indium Tin Ox) is connected via a drain electrode 92b.
ide) The pixel electrode 93b made of a film is connected. Needless to say, the operation of the liquid crystal display device 81 can be performed even if the source region 87b and the drain region 87c are exchanged.

Above the glass substrate 80a on which the semiconductor device having the above-described structure is formed, a counter glass substrate 102 provided with a counter pixel electrode (common electrode) 101 made of an ITO film on the lower surface is provided with a spacer (not shown). Are arranged at a predetermined interval via the. And these glass substrates 80
The periphery of the space forming the pixel matrix portion 86 existing between the a and the opposing glass substrate 102 is sealed with a sealant. The liquid crystal 103 is filled in the sealed space thus formed. The liquid crystal 103 is filled with
Before sealing with the sealant, the liquid crystal 103 is placed on the glass substrate 5.
Alternatively, the glass substrate 80a and the opposite glass substrate 102 may be attached to each other after being dropped on the opposite glass substrate 102, or the liquid crystal 103 may be injected into the sealed space from the inlet of the sealant after sealing with the sealant. The injection or vacuum suction may be performed. Further, the pixel matrix section 8
An alignment film 10 made of polyimide is sandwiched between a glass substrate 5 corresponding to
4 are formed. As shown in FIG. 15, a gate electrode line (scanning line) 105 is connected to the gate electrode 89.

Liquid crystal display device 8 having the above semiconductor device
1 is formed so as to include a TFT which is a semiconductor device obtained by a polysilicon film 87 crystallized by an annealing method performed using the above-described laser irradiation apparatus. Further, according to this annealing method, crystallization of the amorphous silicon film can be promoted to obtain an appropriate electron mobility.

Therefore, the formation of the semiconductor device using the polysilicon film 87 for which the optimum electron mobility has not been obtained is suppressed, and the manufacturing process of the liquid crystal display device 81 incorporating this semiconductor device is suppressed. Can be improved as a result.

The present invention is not limited to the above embodiments, but can be variously modified. For example, in each of the above embodiments, the control of the light intensity of the laser light based on the value detected by the detector may control the incident angle of the laser light to the variable attenuator as in the first embodiment, or As in the third embodiment, a high-voltage power supply for exciting a laser oscillator may be controlled. In short, the intensity of the laser beam may be controlled by any method.

[0090]

As described above, according to the present invention, when the intensity of a laser beam for irradiating an object to be processed is detected and the intensity of the laser beam is controlled, the laser beam for detecting the optical intensity is used. And a laser beam for irradiating the workpiece as little as possible.

Therefore, the light intensity of the laser beam for irradiating the object to be processed can be controlled with high accuracy, and therefore, a high-quality non-single-crystal semiconductor film having high electron mobility and a liquid crystal display having good operating characteristics using the same. A device can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing a laser irradiation apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a part of the apparatus shown in FIG. 1 for removing a part of the laser beam and detecting the intensity thereof.

FIG. 3A is a cross-sectional view showing a beam shape of a laser beam whose energy is made uniform by a homogenizer and whose beam shape is elongated, and FIG. 3B is a sectional view of the laser beam having the same beam shape. FIG. 3 is a distribution diagram showing an energy state.

4A is a distribution diagram showing the energy state in the width direction of the divided laser beam before entering the detector in the state of FIG. 3, and FIG. 4B is similarly formed by a second slit. FIG. 3 is a distribution diagram illustrating an energy state of a divided laser beam.

FIG. 5 is an overall configuration diagram showing a laser irradiation apparatus according to a second embodiment of the present invention.

FIG. 6 is a distribution diagram showing a change in energy intensity distribution before optical adjustment and after optical adjustment.

FIG. 7 is an enlarged view in the state of FIG. 6;

FIG. 8 is a graph showing a correlation between the energy of the first peak generated when the laser irradiation apparatus of the present invention is used and the energy at a processing point at which an optimum grain size is obtained.

FIG. 9 is a distribution diagram showing an example of a laser output waveform generated when using the laser irradiation apparatus of the present invention.

FIG. 10 is a distribution diagram showing an example of a laser output waveform as in FIG. 9;

FIG. 11 is a distribution diagram showing a detailed energy intensity distribution obtained by a beam profiler.

FIG. 12 is a flowchart showing a flow of an annealing process performed by using the laser irradiation apparatus of the present invention.

FIG. 13 is an overall configuration diagram showing a laser irradiation apparatus according to a third embodiment of the present invention.

FIG. 14 is a schematic cross-sectional view showing the structure of a driver monolithic liquid crystal display device obtained in a fourth embodiment of the present invention.

15 is a schematic top view showing a structure of a pixel portion in the device shown in FIG.

FIG. 16 is a schematic perspective view showing scanning of an object to be processed (glass substrate) with laser light.

FIG. 17 is a schematic configuration diagram showing the structure of an LCD unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Laser oscillator 7, 11 ... Homogenizer (light intensity equalization means) 15 ... Condensing lens (condensing optical means) 16 ... 1st slit (forming means) 19 ... Workpiece 21 ... 4th reflection mirror 22 ... Second slit 23 ... Detector 25 ... Control device (control means)

Claims (9)

[Claims] 1. A laser irradiation apparatus for controlling the light intensity of a laser beam to irradiate an object to be processed, wherein a laser oscillator and a portion where the intensity distribution of the laser beam output from the laser oscillator is substantially uniform are formed. Intensity shaping means, a shaping means for removing a part of the laser light passing through the shaping means and shaping it into a predetermined beam shape, and converging the laser light shaped by the shaping means to form the laser beam. Condensing optical means for irradiating the processing object, detecting means for detecting the intensity of the laser light removed by the shaping means, and control means for controlling the intensity of the laser light by a detection signal from the detecting means A laser irradiation device, characterized in that: 2. The laser beam incident on the shaping means,
The beam shape is a rectangular shape having a long part and a short part, and the shaping means removes both ends in the longitudinal direction of the beam shape including a part where the strength is made substantially uniform by the strength equalizing means. The laser irradiation device according to claim 1, wherein 3. The detecting means includes: a reflecting mirror for reflecting the laser light removed by the shaping means in a predetermined direction; a detector on which the laser light reflected by the reflecting mirror is incident; 2. The laser irradiation apparatus according to claim 1, further comprising a slit provided between the mirror and a mirror for removing a part of the laser light incident on the detector. 4. A laser irradiation apparatus for controlling the light intensity of a laser beam to irradiate an object to be processed, comprising: a laser oscillator; and an intensity equalizing means for uniforming the intensity distribution of the laser beam output from the laser oscillator. A condensing optical unit that converges the laser light uniformed by the intensity uniformizing unit and irradiates the object with the laser light; a dividing unit that divides a part of the laser light output from the laser oscillator; Detecting means for detecting the intensity of the laser light split by the splitting means, control means for controlling the intensity of the laser light output from the laser oscillator based on a detection signal from the detecting means, the splitting means and the detecting means And an optical loss substantially equivalent to an optical loss given to the laser light irradiating the object to be processed is divided by the dividing means and detected by the detecting means. The laser irradiation apparatus, characterized in that provided with the equivalent optical means for providing the laser beam. 5. The laser irradiation apparatus according to claim 4, wherein said equivalent optical unit is an optical unit having the same configuration as said intensity equalizing unit and said condensing optical unit. 6. A laser beam is irradiated to an amorphous semiconductor film formed on a substrate through a plurality of optical elements for each shot, and the laser beam is scanned relative to the substrate by a predetermined distance. A method of manufacturing a non-single-crystal semiconductor film, comprising the steps of: polycrystallizing the amorphous semiconductor film by irradiating the laser light; Non-single-crystal semiconductor film, comprising a step of collecting the laser light that has passed through an optical element which is optically closest to the amorphous semiconductor film among the elements, and controlling the energy of the laser light. Manufacturing method. 7. A laser beam is irradiated onto an amorphous semiconductor film formed on a substrate through a plurality of optical elements for each shot, and the laser beam is scanned relative to the substrate by a predetermined distance. In the method for producing a non-single-crystal semiconductor film, the method further comprising: a step of: polycrystallizing the amorphous semiconductor film by irradiation with the laser light. (Integral area value of first pulse in one pulse of laser light × energy at irradiation part of laser light) and (1 of laser light)
Pulse area integral value) or (1 of the laser light)
(Peak value of first pulse in pulse × energy at irradiation part of laser light) and (peak value of first pulse in one pulse of laser light + second pulse in one pulse of laser light) A method for manufacturing a non-single-crystal semiconductor film, comprising: irradiating the laser light with a ratio of (peak value + peak value of a third pulse in one pulse of the laser light) constant. 8. A laser beam is irradiated to an amorphous semiconductor film formed on a first substrate through a plurality of optical elements for each shot, and the laser beam is emitted relative to the first substrate. Irradiating by scanning a predetermined distance,
Non-single-crystallizing the amorphous semiconductor film by irradiating the laser light, and forming the thin film transistor group including a gate electrode line and a source electrode line using the non-single-crystallized amorphous semiconductor film. Forming on a first substrate;
Sealing the first substrate and the second substrate with a liquid crystal interposed between the substrate and a second substrate. The crystallizing step includes a step of collecting the laser light that has passed through the optical element closest to the amorphous semiconductor film optically most of the optical elements, and controlling the energy of the laser light. A method for manufacturing a liquid crystal display device characterized by the above-mentioned. 9. An amorphous semiconductor film formed on a first substrate is irradiated with laser light through a plurality of optical elements for each shot, and the laser light is emitted relative to the first substrate. Irradiating by scanning a predetermined distance,
Non-single-crystallizing the amorphous semiconductor film by irradiating the laser light, and forming the thin film transistor group including a gate electrode line and a source electrode line using the non-single-crystallized amorphous semiconductor film. Forming on a first substrate;
Sealing the first substrate and the second substrate with a liquid crystal interposed between the substrate and a second substrate. The crystallization step includes (area integral value of first pulse in one pulse of the laser beam × energy in the laser beam irradiation part) and (1 of the laser beam).
Pulse area integral value) or (1 of the laser light)
(Peak value of first pulse in pulse × energy at irradiation part of laser light) and (peak value of first pulse in one pulse of laser light + second pulse in one pulse of laser light) A method for manufacturing a non-single-crystal semiconductor film, comprising: irradiating the laser light with a ratio of (peak value + peak value of a third pulse in one pulse of the laser light) constant.