JPH11121378A - Manufacture of polycrystal semiconductor film, manufacture of semiconductor device, manufacture of liquid crystal display, and laser annealing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recognize learning the crystallinity of a semiconductor film during anneal processing, by adjusting energy supplied to an amorphous semiconductor film from a laser beam so that the intensity of a transmitted light or a reflected light detected during irradiation with a laser beam is at a predetermined value. SOLUTION: An inspection light L2 transmitted through a glass substrate 5 is converged by a lens 14. After that, the light becomes incident on a transmitted light detector 15, where the intensity of the light is detected. When amorphous silicon is irradiated with a laser beam L1 , a crystal grows and the transmittance at an annealed portion is abruptly increased. When it is further irradiated with a laser beam, a crystal grows in proportion to provided energy and accordingly the transmittance is gradually reduced (range B). Then, when energy at a certain value or higher is provided, the crystal grain size is abruptly reduced to form particles, thus rapidly increasing the transmittance. As a result, it is appropriate to suspend anneal processing when the transmittance is within the range B. Also, a reflected light may be used instead of the transmitted light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a polycrystalline semiconductor film by irradiating a laser beam to crystallize an amorphous semiconductor film, a method for manufacturing a semiconductor device using the method, and a liquid crystal display. The present invention relates to a method for manufacturing a device and a laser annealing device used for these methods.

[0002]

2. Description of the Related Art In recent years, a liquid crystal display (LCD: Lithium) which consumes little power, is thin, and is lightweight as a display used for a personal computer, a word processor or the like.
quidCrystal Display) is often used. Among them, an active matrix type liquid crystal display device using a thin film transistor (TFT: Thin Film Transistor) using an amorphous silicon (a-Si) film as a switching element as a semiconductor material has a large number of pixels. However, it is used as a display device for a full-color television or an OA, since there is no deterioration in contrast and response and half-tone display is possible.

An amorphous silicon film has a much lower electron mobility than a crystalline silicon film (single-crystal silicon film and polycrystalline silicon film), and therefore drives a TFT in a driving portion or a pixel portion which requires high-speed operation. A-S
The TFT of i cannot be used, and instead, an IC is electrically connected to the pixel portion for driving.

However, when the IC is used as described above, there is a problem that the reliability of operation is lowered and the cost is increased. Further, as the definition of the display screen is advanced, the pixel pitch is narrowed. Therefore, the connection distance between the IC and the pixel portion is shortened and the number of connection points is increased, so that the above-described problems of reliability and cost become remarkable.

Therefore, the amorphous silicon film formed on the substrate is irradiated with laser light to convert the amorphous silicon film into polycrystalline (poly) silicon (poly-Si).
Excimer laser annealing (ELA: Excime) to form a semiconductor film with high electron mobility
r Laser Anneal) technology is being developed. According to this process, since the amorphous silicon film is instantaneously melted and crystallized, the polycrystalline 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 polycrystalline silicon film can be formed using a large-area and inexpensive glass substrate.

Here, the magnitude of the electron mobility is μ = | v _d
/ E | (cm ² / S · V), and the average electron moving speed (drift speed: v _d ) in the crystal when an electric field E (V / cm) is applied to the crystal. (Cm / s)) per unit electric field magnitude. In addition, amorphous silicon includes a state in which phase transition 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 a polycrystalline silicon film to be obtained can be obtained if the ratio of amorphous silicon is reduced after annealing by laser light and polycrystallization can be performed.

When such a polycrystalline silicon film is used, a thin film transistor having high electron mobility can be formed on a glass substrate by a low-temperature process. According to this polycrystalline silicon TFT, the above-mentioned problem is solved, and a thin and high-definition liquid crystal display device called a driver monolithic type in which a driver TFT and a pixel TFT are formed on a glass substrate can be obtained.

When an amorphous silicon film is changed to a polycrystalline silicon film by annealing with a laser beam, the polycrystalline silicon film has an appropriate crystal state (particle size: 0.2 to 1) during the annealing process by in-process. A technique for monitoring whether or not it is formed to a thickness of 0.0 μm or more is disclosed in JP-A-3-972.
Japanese Patent Application Laid-Open No. 19-19519 discloses a technique for optimizing the crystal state of a substrate to be processed based on the detected light intensity while irradiating inspection light.

However, in the case of this technique, only the crystal state before and after the annealing treatment can be known.
A subtle difference in the crystal state during the annealing process cannot be detected. In addition, since the crystal state of the processing substrate is optimized only by the light intensity of the inspection light, it is possible to know the portion of the amorphous silicon film that is not melted due to insufficient heating. Is excessively heated even if is melted, resulting in granular fine crystal grains (particle size: 0.01 to 0.02 μm).
m), that is, microcrystal silicon (μ-c
It is not possible to detect the portion where Si) is formed. The average electron mobility is extremely low in the portion where the granular fine crystal grains are formed. Therefore, the average electron mobility of 100 (cm ² / S · V) or more, which is considered appropriate for the fabrication of the driving TFT, is used. The electron mobility cannot be obtained. Therefore, it is impossible to know whether the polycrystalline silicon film is formed uniformly by this method, and it is conceivable that the yield may be reduced when manufacturing the TFT.

Further, a similar technique is disclosed in Japanese Patent Laid-Open No. 8-236.
JP-A-440 and JP-A-9-102468 disclose that an amorphous silicon thin film on a glass substrate is annealed with an excimer laser while irradiating inspection light, and the degree of crystallization is determined using transmitted light of the inspection light. The disclosed technology is disclosed.

However, in the case of this technique, since the annealing is completed at the portion where the transmittance becomes constant, the above-mentioned granular μ-cSi is formed, and good polycrystallization is achieved. It is hard to say that it is.

[0012]

As described above, when crystallizing an amorphous semiconductor film, the crystallinity could not be known during the annealing process, so that the annealing process can be performed properly and reliably. There was a problem that could not be performed.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide a method of manufacturing a polycrystalline semiconductor film in which the crystallinity of a semiconductor film can be known during an annealing process. To provide.

Another object of the present invention is to provide a method of manufacturing a semiconductor device and a method of manufacturing a liquid crystal display device using the method of manufacturing a polycrystalline semiconductor film, and a laser annealing apparatus used to embody these methods. To provide.

[0015]

According to the present invention, according to the first aspect, a step of irradiating an amorphous semiconductor film formed on a substrate with a laser beam while scanning the substrate relative to the substrate by a predetermined distance. And a step of polycrystallizing the amorphous semiconductor film by irradiating the laser light, and irradiating inspection light to a portion of the substrate on which the laser light is irradiated, and detecting transmitted light or reflected light thereof. Monitoring whether or not polycrystallization of the amorphous semiconductor film is performed under predetermined conditions, wherein the transmitted light or the light detected during the irradiation of the laser light. Detecting whether or not the intensity of the reflected light is a predetermined value, and adjusting the energy received by the amorphous semiconductor film from the laser beam so as to be the predetermined value when the intensity is not the predetermined value. Process and before And wherein said laser beam based on the adjustment to a step of irradiating to the amorphous semiconductor film.

According to a second aspect of the present invention, in the first aspect of the present invention, the predetermined value is an intensity at which the transmittance of the detected transmitted light is 70% or less or the reflectance of the reflected light is 30% or more. It is characterized by being.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the inspection light is irradiated from the opposite direction to the irradiation of the laser light through the substrate.

According to a fourth aspect of the present invention, in the first or second aspect, the laser light and the inspection light are emitted from one light source. According to a fifth aspect of the present invention, in the method according to any one of the first to fourth aspects, the step of adjusting the energy includes a method of increasing an energy of the laser light itself or a method of increasing the energy of the laser light. The method is characterized in that it is performed by at least one of the methods of changing the number of times of irradiation on the substrate.

According to a sixth aspect of the present invention, the step of irradiating a laser beam to amorphous silicon formed in a film shape on a substrate while scanning the substrate relative to the substrate by a predetermined distance, A step of polycrystallizing the amorphous silicon by irradiating light, and irradiating the laser light irradiation site on the substrate with inspection light and detecting transmitted light or reflected light thereof to detect the amorphous silicon. Monitoring whether polycrystallization is performed under predetermined conditions, forming a gate insulating film, forming a gate electrode on the gate insulating film, and adding a source to the polycrystallized silicon. Forming a region and a drain region; forming an interlayer insulating film in a region including over the gate electrode; and forming a contact hole in the interlayer insulating film over the source region and the drain region. Forming a source electrode so as to connect to the source region via a contact hole formed on the source region, and connecting to the drain region via a contact hole formed on the drain region. Forming a drain electrode formed on the semiconductor device, detecting whether the intensity of the transmitted light or the reflected light detected during the irradiation of the laser light is a predetermined value or not. Adjusting the energy received by the amorphous silicon from the laser light so that the intensity becomes the predetermined value when the intensity is not the predetermined value; and adjusting the laser light to the amorphous silicon based on the adjustment. Irradiating silicon.

According to a seventh aspect of the present invention, in the sixth aspect of the invention, the predetermined value is an intensity at which the transmittance of the detected transmitted light is 70% or less or the reflectance of the reflected light is 30% or more. It is characterized by being.

According to an eighth aspect of the present invention, in the invention of the sixth or seventh aspect, the inspection light is applied through the substrate in a direction opposite to the direction of the laser light.

According to a ninth aspect of the present invention, the laser light and the inspection light are emitted from one light source in the invention of the sixth or seventh aspect. According to a tenth aspect of the present invention, in the invention according to any one of the sixth to ninth aspects, the step of adjusting the energy includes a method of increasing an energy of the laser light itself or a method of increasing the energy of the laser light. The method is characterized in that it is performed by at least one of the methods of changing the number of times of irradiation on the substrate.

According to an eleventh aspect of the present invention, while irradiating a laser beam to amorphous silicon formed in a film on the first substrate, the amorphous silicon is scanned relative to the first substrate by a predetermined distance. Causing the amorphous silicon to polycrystallize,
It is determined whether polycrystallization of the amorphous silicon is performed under predetermined conditions by irradiating inspection light on a portion irradiated with the laser light on the first substrate and detecting transmitted light or reflected light thereof. Monitoring, forming scan lines and gate electrodes on the first substrate, forming signal lines, drain electrodes, and source electrodes on the first substrate;
Forming a pixel electrode so as to be connected to the drain electrode or the source electrode; forming a common electrode on a second substrate; and forming a liquid crystal between the first substrate and the second substrate. Wherein the step of polycrystallizing the amorphous silicon includes the step of polycrystallizing the amorphous silicon, the step of polycrystallizing the amorphous silicon, Detecting whether or not the intensity is a predetermined value, and if the intensity is not the predetermined value, adjusting the energy received by the amorphous silicon from the laser light so as to be the predetermined value; Irradiating the laser light to the amorphous silicon based on the adjustment.

According to a twelfth aspect of the present invention, there is provided an eleventh aspect.
In the invention, the predetermined value is such that the transmittance of the detected transmitted light is 70% or more or the reflectance of the reflected light is 30%.
It is characterized by the following strength.

According to the present invention, the present invention is characterized in that:
Alternatively, in the twelfth aspect of the invention, the inspection light is irradiated from the opposite direction to the irradiation of the laser light through the substrate.

According to the present invention, the present invention is characterized in that:
Alternatively, in the twelfth aspect, the laser light and the inspection light are emitted from one light source. According to a fifteenth aspect of the present invention, in the method according to any one of the eleventh to fourteenth aspects, the step of adjusting the energy includes a method of increasing the energy of the laser light itself or the method of increasing the energy of the laser light. The method is characterized in that it is performed by at least one of the methods of changing the number of times of irradiation on the substrate.

According to a sixteenth aspect of the present invention, in the laser annealing apparatus, a laser beam is emitted to an amorphous semiconductor film formed on an object to be processed and the amorphous semiconductor film is polycrystallized. 1 laser light source, a second laser light source that emits inspection light for irradiating a portion of the amorphous semiconductor film irradiated with the laser light, and each light emitted from these laser light sources is introduced. A chamber in which the object to be processed is installed, light intensity detecting means for detecting the intensity of transmitted light or reflected light from the irradiated portion of the inspection light during the irradiation of the laser light, Determining means for determining the degree of crystallization of the amorphous semiconductor film based on the transmittance or reflectance obtained by the detection by the means, and the laser light and the inspection light relative to the object to be processed. And having a scanning means for 査.

According to claim 17 of the present invention, claim 16
In the invention, the first laser device and the second laser device are arranged to face each other with the object to be processed interposed therebetween.

According to the present invention, in a laser annealing apparatus, a laser beam is emitted to an amorphous semiconductor film formed on an object to be processed and the amorphous semiconductor film is polycrystallized. A light source, a chamber in which each light emitted from the laser light source is introduced and the object to be processed is installed therein, and the intensity of the transmitted light or the reflected light of the laser light during the irradiation of the laser light. Light intensity detecting means for detecting, determining means for determining the degree of crystallization of the amorphous semiconductor film based on transmittance or reflectance obtained by the detection by the light intensity detecting means, Scanning means for relatively scanning the laser light and the inspection light.

According to these inventions, it is possible to know whether or not the crystallinity is appropriate during the annealing process, and it is possible to obtain an index for the optimal annealing process in-process. A high-quality polycrystalline semiconductor film with such crystallization can be obtained. Therefore, as a result, a semiconductor device or a liquid crystal display device having favorable operation characteristics can be obtained.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example of a first embodiment according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a laser annealing apparatus according to the present embodiment, and FIG. 2 is a schematic diagram of a configuration of the laser annealing apparatus. In FIG. 2, two reflection mirrors are not shown.

[0032] The laser annealing device has a first laser device 1 outputs laser light L ₁ for heating (annealing). An excimer laser is used as the first laser device.
XeCl that oscillates 8 nm light is used, but Ar
Other laser media such as F and KrF may be used.

The laser light L ₁ emitted from the first laser device 1 is reflected by the reflection mirror 2 and enters the attenuator (attenuator) 3. By passing through the attenuator 3, the laser beam L ₁ is the energy density is finely adjusted.

The laser beam L ₁ emitted from the attenuator 3 is reflected again by the reflection mirror 2 and enters the shaping optical system (homogenizer) 4. This shaping optical system 4
The intensity distribution of the laser beam L ₁ (here, having a cross section of about 20 mm × 30 mm) emitted from the first laser device 1 is made uniform, and the shape of the beam cross section is set to 200 m.
It can be shaped into an mx 0.5 mm band (a so-called line beam). In the above-described apparatus, the shape of the beam irradiation surface can also be shaped into a rectangle having a side of about 2 to 10 mm, and can be properly used depending on the purpose and shape of the object to be annealed.

The laser light L ₁ emitted from the shaping optical system 4
Is further reflected by the reflection mirror 2 and then substantially perpendicularly enters the glass substrate 5 (thickness: 1.0 mm) of the substrate to be annealed which is installed in an airtight chamber (not shown). On the upper surface of this glass substrate, as shown in FIG.
iO _x , SiN _x and even TEOS (Tetra Ethyl Ort)
ho Silicate: an undercoat 6 made of Si [OC ₂ H ₅ ] ₄ ) and an amorphous silicon (a-Si) thin film 7 which is an amorphous semiconductor film are sequentially laminated and formed. I have. The irradiation of the laser beam L ₁ described above is carried out from the amorphous silicon thin film 7 side.

[0036] by the action of the laser beam L _1, the amorphous silicon thin film 7 is annealed as described later. Here, as a film forming means, usually, CVD (Chemic
alVapor Deposition) is used.

The glass substrate 5 is placed on the stage 8. The stage 8 is driven by the driving means 9 to transmit the laser light L
It is driven in the X and Y directions while receiving the irradiation of _1. The control is performed by the control means 11. A hole is formed in the bottom surface so that transmitted light can pass therethrough.

A second laser device 12 is disposed obliquely above the glass substrate placed on the stage 8 (in this embodiment, above 30 degrees). The second laser device 12 includes a He—Ne laser (wavelength: 633 nm),
and outputs visible light by an r ⁺ laser (wavelength: 488 nm to 514 nm) or the like.
Amorphous silicon film 7 annealed by ₁
It is utilized as the inspection light L ₂ which detect the crystallization conditions.
In this embodiment, a He-Ne laser is used.

The inspection light L ₂ output from the second laser device 12 is converged by the lens 13 and
Irradiating the same site which has been irradiated by the laser beam L _1. Inspection light L ₂ incident on the glass substrate 5, so that the partially reflected by the glass substrate 5, the remainder is transmitted through the glass substrate 5.

The inspection light L ₂ transmitted through the glass substrate 5 is converged by the lens 14 and then enters the transmitted light detector 15 where the intensity is detected. The transmitted light detector 15 has no sensitivity in the ultraviolet region, but having sensitivity in the visible region in accordance with the inspection light L _2. Then, a detection signal from the transmitted light detector 15 is input to the control device 11.

Based on the detection signal detected by the transmitted light detector 15, the transmittance of the inspection light L ₂ transmitted through the amorphous silicon film 7 is guided by the transmittance detection unit 16 provided in the control device 11. The transmittance is also calculated by a comparison operation between the intensity and the intensity before transmission measured by a measuring unit (not shown), and the annealing state of the amorphous silicon film 7 is determined by the determination unit 17 based on the transmittance. The output of the first laser device 1 and the attenuation rate of the attenuator 3 are controlled to optimal values by the command unit 18 of the control device 11 according to the determination result of the determination unit 17.
The coordinates on the glass substrate 5 of the site where the determination result is obtained are stored in the storage unit 19.

The present inventor irradiates a portion on the glass substrate 5 irradiated with the laser beam L ₁ with the inspection light L ₂ , and the intensity of light transmitted through the irradiated portion has a close relationship with the quality of annealing. I found something.

[0043] Figure 4 is a graph showing the energy and type of the transmission and the crystalline state of the inspection light L ₂ which receives the glass substrate 5 which is irradiated by the laser beam L _1. According to this result, as the irradiation energy increases, amorphous silicon (a-Si ‥ A region) and polycrystalline silicon (p
It can be seen that the crystal state changes with the poly-Si ‥ B region) and the microcrystalline silicon (μ-cSi ‥ C region).

The crystals when irradiated with laser light L ₁ to the amorphous silicon is grown (poly reduction), the transmittance in the annealing section is rapidly increased (A region). When the laser light is further applied, the crystal grows in proportion to the applied energy, and the transmittance gradually decreases accordingly (region B). And when given more than a certain energy value,
The crystal grain size rapidly decreases, becomes granular, and the transmittance sharply increases (C region).

As a result, it can be seen that the annealing can be stopped when the transmittance is in the region B (before shifting to the region C) in order to prevent the granular crystal state and keep the electron mobility high. . In particular, under the conditions of the following film thickness, irradiation energy, and the like, optimal polycrystallization was achieved when the transmittance was 70% or less in the B region.

The laser light L ₁ and the inspection light L at the time of this measurement
Data according to ₂ is obtained when the amorphous silicon film 7 is annealed under the following conditions. Use words, as the inspection light L _2, using the light emitted from the He-Ne laser output 25 mW, the laser light L ₁ for annealing, the light emitted from the XeCl laser pulse width 25ns output 200W Was.

The undercoat 6 is made of SiO _x and has a thickness of 0.35 μm to 0.40 μm. The thickness of the amorphous silicon film 7 is 50 n.
m to 100 nm. Further, the transmitted light detector 15 has 1
A PIN silicon diode having a time constant of 0 ns is used.

Next, FIG. 5 shows the crystal particle size and the inspection light L when the irradiation energy density (fluence: J / cm ² ) of the laser light L ₁ during the above-mentioned annealing treatment is changed. ₂ shows the relationship with the transmittance of transmitted light to the glass substrate 5. Irradiation frequency of the laser light L ₁ at each irradiation energy density at that time is fixed at 40 times. According to this graph, it can be seen that when the transmittance suddenly increases to 70% or more after reaching the minimum value, the crystal grain size sharply decreases and the crystal becomes granular.

FIG. 6 shows the crystal grain size and the transmission of the inspection light L ₂ transmitted through the glass substrate 5 when the number of irradiations of the laser light L ₁ is changed during the above-described annealing treatment. The relationship with the rate is shown. Irradiation energy of the laser light L ₁ at each number of times of irradiation that time, 350 mJ / pul
It is constant at se. According to this graph, it can be seen that when the transmittance suddenly increases to 70% or more after reaching the minimum value, the crystal grain size sharply decreases and the crystal becomes granular.

Based on the experimental results thus far, while measuring the transmittance in-process until the transmittance of the inspection light L ₂ transmitted from the glass substrate 5 at the annealing portion becomes 70% or less, The control signal is sent to the first laser device 1 and the attenuator 3 by feeding back the result to the control device 11, and the laser light L ₁ from the first laser device 1 is transmitted.
The annealing process is continued by changing the output of the attenuator 3 and the attenuation rate of the attenuator 3. Thereby, the particle size is 0.2 ~
Annealing can be performed under the optimal conditions for performing polycrystallization of 1.0 μm or more. That is, the waveform detected by the transmittance detection unit 18 provided in the control device 11 is determined by the determination unit 1.
In 9, the degree of crystallization of the amorphous silicon film 7 can be determined almost simultaneously with the irradiation of the laser beam L ₁ by determining whether or not the above transmittance is satisfied.

Since the progress of such crystallization can be simultaneously detected in-process while annealing the amorphous silicon film 7 as described above, it is immediately fed back to the first laser device 1 according to the detection result. To change the annealing conditions. That is, instead of monitoring the output variation of the laser beam L ₁ itself even if there is variation in the thickness of the film formation by CVD, in order to directly monitor the progress of the crystallization annealing section,
Crystallization to a predetermined grain size can be achieved by minimizing the region where annealing failure occurs in the glass substrate 5.

The shape of the crystal grains is flat in the thickness direction of the amorphous silicon film 7 and substantially circular in the upper surface direction. Here, the particle size refers to the average diameter of individual crystal grains in this substantially circular portion.

Next, FIG. 7 shows a laser annealing apparatus according to a second embodiment of the present invention which can perform measurement only with the first laser apparatus 1 without using the second laser apparatus 12. Show. This device has the same configuration as that of FIG.
2 and a half mirror 21 and a photodetector 22 as other components. The half mirror 23 is to irradiate branches to the laser beam L ₁ photodetector 24 and the glass substrate 5 that will be described later is ultraviolet light emitted from the first laser unit. The light detector 22 is
The laser beam L ₁ ′ branched by the half mirror 23 and not transmitted through the glass substrate 5 is received and its intensity is detected. And its intensity, the transmittance of the laser beam L ₁ is calculated and compared by the detection result to the control unit 11 in the transmitted light detector 15 to the glass substrate 5.

Then, as described above, the transmittance of the inspection light L ₂ transmitted from the glass substrate 5 at the annealing portion is 70%.
The result is fed back to the control device 11 while measuring the transmittance in-process until it becomes the following, thereby sending a control signal to the first laser device 1 or the attenuator 3 and transmitting the control signal from the first laser device 1. by changing the attenuation factor of the output and the attenuator 3 of the laser beam L _1, we continue annealing. Thereby, the particle size is 0.2 μm to 1.0 μm.
Annealing can be performed under the optimal conditions for polycrystallization of μm or more. In this case, since the visible light is not used, the transmitted light detector 15 and the light detector 22 are not used.
Has a detection sensitivity in the ultraviolet region.

In the first embodiment described above, the inspection light L ₂ and the laser light L ₁ are applied to the glass substrate 5 from the same direction with respect to the glass substrate 5. it is conceivable to L ₂ and the laser light L ₁ is irradiated to the glass substrate 5 from different directions with respect to the glass substrate.

In this case, the lower surface of the amorphous silicon film 7 (the surface opposite to the surface where the laser beam L ₁ is irradiated) is such that the cooling after the annealing and the re-solidification after the melting by the inspection light L ₂ progress quickly. , The change in crystal grain size can be detected quickly. This can be detected by a modified laser annealing apparatus of the first embodiment as shown in FIG. This device is obtained by moving the second laser device 12 in the device shown in FIG.
In this device, components having the same reference numerals as those in the devices of FIGS. 1 and 2 have the same operation.

FIG. 9 corresponds to FIGS. 5 and 6.
Also, as shown in FIG. 10, the characteristic of crystallization is obtained in the reflected light with respect to the glass substrate 5. First irradiation energy density of the laser beam L ₁ in the case of performing the above-described annealing process in FIG. 9 (fluence: J / cm ²⁾ glass substrate 5 particle size of the crystals of the inspection light L ₂ at the time of changing the Is shown with respect to the reflectance of the reflected light. Irradiation frequency of the laser light L ₁ at each irradiation energy density at that time is fixed at 40 times. According to this graph, it can be seen that when the reflectance suddenly decreases to 30% or less after reaching the maximum value, the crystal grain size sharply decreases and the crystal becomes granular.

FIG. 10 shows the crystal grain size and the reflection of the inspection light L _{2 on} the glass substrate 5 when the number of irradiations of the laser light L ₁ is changed during the above-mentioned annealing treatment. The relationship with the rate is shown. Irradiation energy of the laser light L ₁ at each number of times of irradiation that time, 350 mJ / pu
It is constant at 1se. According to this graph, when the reflectance suddenly decreases to 30% or less after reaching the maximum value,
It can be seen that the grain size of the crystals is sharply reduced and becomes granular.

Based on the experimental results so far, the reflectivity of the inspection light L ₂ was measured in-process until the reflectivity of the inspection light L _{2 from} the glass substrate 5 at the annealing portion became 30% or more. The control signal is sent to the first laser device 1 and the attenuator 3 by feeding back the result to the control device 11, and the laser light L ₁ from the first laser device 1 is transmitted.
The annealing process is continued by changing the output of the attenuator 3 and the attenuation rate of the attenuator 3. Thereby, the particle size is 0.2 μm
Annealing can be performed under optimal conditions for polycrystallization of 1.0 μm or more.

FIG. 11 shows a laser annealing apparatus according to a third embodiment of the present invention utilizing such a detection result of reflected light. This apparatus is basically the same as the apparatus shown in FIG. 2, but uses reflected light instead of transmitted light to the glass substrate 5, so that the transmitted light detector 15 is used as the reflected light detector 23 and the transmittance detection is performed. The unit 16 is a reflectance detecting unit 2
It is set to 4. The other configuration is the same as that of the apparatus shown in FIG. 2, and thus the operation is the same.

The laser annealing apparatus shown in FIG.
FIG. 8 relates to a modification of the third embodiment.
This device is configured so that detection can be performed in accordance with the reflected light from the glass substrate 5. 8 and 11 have the same function.

By annealing the amorphous silicon film 7 provided on the glass substrate 5 in this manner, a polysilicon film as a polycrystalline semiconductor thin film is formed on the glass substrate 5, and a T film as a semiconductor device is formed.
FT will be formed. Next, the glass substrate 5 is assembled into a liquid crystal display device.

Now, a driver monolithic liquid crystal display device embodied by these laser annealing apparatuses and made of polycrystalline silicon manufactured by using the above-described method of manufacturing a semiconductor film is described in the present invention. A description will be given as a fourth embodiment. FIG. 13 shows the liquid crystal display device 31. The spacers, color filters, light shielding films, polarizing plates, and the like are not shown. On the glass substrate 5 of the liquid crystal display device 31, a coplanar thin film transistor as the above-mentioned semiconductor device is formed through a normal photolithography process or the like. That is, P-type TFT
32, an N-type TFT 33 and a pixel TFT 34 are formed. The P-type TFT 32 and the N-type TFT 33 form a driving unit 35 and are complementary transistors. Pixel TF
T34 forms a pixel matrix section (display section) 36.

Each of the TFTs 32, 33, and 34 has an underlayer in which a silicon film (hereinafter, referred to as a polysilicon film) 37 obtained by crystallizing an amorphous silicon film by the above-described annealing method is formed on the glass substrate 5 in a predetermined shape. It is laminated on the coat 6. This polysilicon film 37 has
A channel region 37a serving as a passage through which electrons flow, and impurities (donor / acceptor) such as P (phosphorus) and B (boron)
Doped source region 37b and drain region 37
c.

The polysilicon film 37 is a gate insulating film 38
Covered by A gate electrode 39 is formed on the gate insulating film 38, and the gate electrode 39 is covered with an interlayer insulating film 41. A contact hole is provided in the interlayer insulating film 41, and a source electrode 42a connected to the source region 37b and a drain electrode 42b connected to the drain region 37c are formed through the contact hole. Further, a source electrode line (signal line) 43a is connected to the pixel TFT 34 via a source electrode 42a, and ITO (Indium Tin O 2) is connected via a drain electrode 42b.
xide) The pixel electrode 43b made of a film is connected. It goes without saying that the operation of the liquid crystal display device 31 can be performed even if the source region 37b and the drain region 37c are exchanged.

Above the glass substrate 5 on which the semiconductor device having the above structure is formed, a counter glass substrate 52 provided with a counter pixel electrode (common electrode) 51 made of an ITO film on the lower surface is provided with a spacer (not shown). Are arranged at predetermined intervals. The periphery of the space forming the pixel matrix portion 36 existing between the glass substrate 5 and the counter glass substrate 52 is sealed with a sealant. The liquid crystal 53 is filled in the sealed space thus formed. The liquid crystal 53 is filled with the liquid crystal 53 before sealing with the sealing agent.
2 and a glass substrate 5 and a counter glass substrate 52
After sealing with the sealant, the liquid crystal 53 may be injected into the sealed space from the inlet of the sealant or may be vacuum-sucked. Furthermore,
An alignment film 54 made of polyimide is formed on the glass substrate 5 and the opposing glass substrate 52 corresponding to the pixel matrix portion 36 with the liquid crystal 53 interposed therebetween. As shown in FIG. 14, a gate electrode line (scanning line) 55 is connected to the gate electrode 39.

Liquid crystal display device 3 having the above semiconductor device
1 is formed by the polysilicon film 37 crystallized by the above-described annealing method. According to this annealing method, the progress of crystallization of the amorphous silicon film 7 can be detected during annealing.

Therefore, since the semiconductor device is not formed using the polysilicon film 37 which is not crystallized with the optimum grain size, the yield of the liquid crystal display device 31 incorporating this semiconductor device is reduced as a result. Can be improved.

The present invention is not limited to the above-described embodiment, and can be variously modified without departing from the gist of the invention. For example, the waveform of the light detected by the transmitted light detector 15 or the reflected light detector 25 and the optimum annealing state can be basically determined by the transmittance or the reflectance of the inspection light as described above. .

However, the conditions at that time vary depending on the thickness of the amorphous silicon film 7 and the thickness and material of the undercoat 6. Therefore, it is necessary to change the numerical values of the above-described determination conditions according to the thickness of the amorphous silicon film 7 to be annealed and the thickness and material of the undercoat 6.

In the embodiment of the present invention, as a method of manufacturing a polycrystalline semiconductor film, the annealing state is determined based on the intensity of light detected by the transmitted light detector 15 or the reflected light detector 25 for each shot of excimer laser light. May be determined, but the present invention is not limited to this. Although the beam spot diameter of the laser light L ₁ of shaping line beam inspection light L ₂ than the width of a principle that is set smaller, 300 [mu] m for example, a width of the line beam, 30.mu. beam spot diameter
m Distant scans every shot of the laser beam L ₁ a line beam at a pitch of 30 [mu] m. In that case, a predetermined portion of the amorphous silicon film 7 becomes a receiving irradiation of the laser light L ₁ of 10 shots. Even in such a case, it is sufficient that not only the annealing state can be determined for every shot but also the annealing state for at least the last shot can be determined. This is because the energy given by the last shot has the greatest effect on the melting and resolidification of the amorphous silicon film 7.

Further, a coplanar TFT having a single gate electrode has been described as an example of a semiconductor device manufactured using polycrystalline silicon obtained in the embodiment of the present invention. Needless to say, a dual gate coplanar TF is used.
T may be used, staggered TFT and inverted staggered TFT
But it is good. Of course, if amorphous silicon is used after being poly-crystallized, it may be used for other types of semiconductor devices typified by ordinary CMOS, bipolar transistors, static induction transistors, SRAMs, DRAMs and the like. This is because the object of the present invention is to favorably polycrystallize an amorphous semiconductor film.

[0073]

According to the present invention, the progress of crystallization can be known during the annealing process, and an index for the optimal annealing process can be obtained in-process. Therefore, a high-quality polycrystalline semiconductor film with uniform crystallization can be manufactured, and thus a semiconductor device and a liquid crystal display device having good operation characteristics can be manufactured.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a laser annealing apparatus according to a first embodiment of the present invention.

FIG. 2 is an overall configuration diagram showing the laser annealing apparatus of FIG. 1;

FIG. 3 is a partial cross-sectional view of a glass substrate on which an amorphous silicon film is formed via an undercoat.

FIG. 4 is a relationship diagram showing the transmittance of inspection light transmitted through a glass substrate during annealing, the irradiation energy to the glass substrate, and the crystal state.

FIG. 5 is a graph showing the grain size of the crystals at the time of changing the irradiation energy density of the laser beam L _1, the relationship between the transmittance of the transmitted light to the glass substrate of the inspection light L _2.

Figure 6 is a graph illustrating the relationship between the transmittance of the transmitted light to the glass substrate 5 of the inspection light L ₂ with the particle size of the crystals when changing the irradiation frequency of the laser beam L _1.

FIG. 7 is an overall configuration diagram showing a laser annealing apparatus according to a second embodiment of the present invention.

FIG. 8 is an overall configuration diagram showing a modified example of the laser annealing apparatus according to the first embodiment of the present invention.

9 is a graph showing the grain size of the crystals at the time of changing the irradiation energy density of the laser beam L _1, the relationship between the reflectance of the reflected light to the glass substrate of the inspection light L _2.

Figure 10 is a graph showing the relationship between the reflectance of the reflected light to the glass substrate 5 of the inspection light L ₂ with the particle size of the crystals when changing the irradiation frequency of the laser beam L _1.

FIG. 11 is an overall configuration diagram showing a laser annealing apparatus according to a third embodiment of the present invention.

FIG. 12 is an overall configuration diagram showing a modified example of the laser annealing apparatus according to the third embodiment of the present invention.

FIG. 13 is a sectional view showing a part of a liquid crystal display device according to a fourth embodiment of the present invention, which is manufactured using the laser annealing apparatus of the present invention.

14 is a top view of a pixel matrix portion in the liquid crystal display device of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st laser apparatus, 2 ... Reflection mirror, 3 ... Attenuator, 4 ... Homogenizer 5 ... Glass substrate, 6 ... Undercoat, 7 ... Amorphous silicon film 8 ... Stage, 9 ... Driving means, 11 ... Control device, 12 …
Second laser device 13, 14: lens, 15: transmitted light detector, 16: transmittance detection unit, 17: determination unit 18: command unit, 19: storage unit, 21: half mirror, 2
2 photodetector 23 reflected light detector 24 reflectance detector 31 liquid crystal display device 32 P-type TFT 33 N-type TFT 34 pixel TF
T, 35: drive unit 36: pixel matrix unit, 37: polysilicon film, 38
... gate insulating film 39 ... gate electrode, 41 ... interlayer insulating film, 51 ... counter pixel electrode 52 ... counter glass substrate, 53 ... liquid crystal, 54 ... alignment film, 5
5 ... Gate electrode line

Claims (18)

[Claims] A step of irradiating an amorphous semiconductor film formed on a substrate with a laser beam and scanning the substrate by a predetermined distance relative to the substrate; A step of polycrystallizing the film, and irradiating the laser light irradiation site on the substrate with test light and detecting transmitted light or reflected light thereof, thereby performing polycrystallization of the amorphous semiconductor film in a predetermined manner. Monitoring whether or not the condition is performed under a condition. Detecting whether or not the intensity of the transmitted light or the reflected light detected during the irradiation of the laser light is a predetermined value. And adjusting the energy received by the amorphous semiconductor film from the laser light so that the intensity becomes the predetermined value when the intensity is not the predetermined value. Amorphous Irradiating the semiconductor film. 2. The predetermined value is such that the detected transmittance of the transmitted light is 70% or less or the reflectance of the reflected light is 30%.
2. The method for manufacturing a polycrystalline semiconductor film according to claim 1, wherein the strength is as described above. 3. The method for manufacturing a polycrystalline semiconductor film according to claim 1, wherein the inspection light is applied from a direction opposite to the irradiation of the laser light through the substrate. 4. The method according to claim 1, wherein the laser light and the inspection light are emitted from one light source. 5. The method according to claim 1, wherein the step of adjusting the energy is performed by at least one of a method of increasing the energy of the laser light itself and a method of changing the number of times of irradiation of the substrate with the laser light. Item 1
The method of manufacturing a polycrystalline semiconductor film according to claim 1. 6. A step of irradiating amorphous silicon formed in a film shape on a substrate with a laser beam while scanning said substrate relative to said substrate by a predetermined distance, and irradiating said amorphous silicon with said laser beam. Polycrystallizing the amorphous silicon, and irradiating the laser light irradiation portion on the substrate with the inspection light and detecting the transmitted light or the reflected light to perform the polycrystallization of the amorphous silicon in a predetermined manner. Monitoring the condition, forming a gate insulating film, forming a gate electrode on the gate insulating film, and forming a source region and a drain region in polycrystalline silicon. Forming an interlayer insulating film in a region including on the gate electrode, and forming a contact hole in the interlayer insulating film on the source region and the drain region;
A source electrode is formed to connect to the source region via a contact hole formed on the source region, and formed to connect to the drain region via a contact hole formed on the drain region. Forming a drain electrode, wherein the step of detecting whether or not the intensity of the transmitted light or the reflected light detected during the irradiation of the laser light is a predetermined value; and Adjusting the energy received by the amorphous silicon from the laser light so as to be the predetermined value when is not the predetermined value; and irradiating the amorphous silicon with the laser light based on the adjustment. And a method of manufacturing a semiconductor device. 7. The predetermined value is such that the transmittance of the detected transmitted light is 70% or less or the reflectance of the reflected light is 30%.
7. The method for manufacturing a semiconductor device according to claim 6, wherein the strength is as described above. 8. The method of manufacturing a semiconductor device according to claim 6, wherein the inspection light is applied through the substrate in a direction opposite to the direction of the laser light. 9. The method according to claim 6, wherein the laser light and the inspection light are emitted from one light source. 10. The method according to claim 1, wherein the step of adjusting the energy is performed by at least one of a method of increasing the energy of the laser light itself and a method of changing the number of times of irradiation of the substrate with the laser light. The method of manufacturing a semiconductor device according to claim 6. 11. The amorphous silicon formed in a film on the first substrate by irradiating the amorphous silicon with a laser beam by a predetermined distance relative to the first substrate. Polycrystallizing the amorphous silicon, and irradiating the laser light irradiation site on the first substrate with inspection light and detecting transmitted light or reflected light thereof, thereby performing polycrystallization of the amorphous silicon. Monitoring the operation under the following conditions; forming scan lines and gate electrodes on the first substrate; and forming signal lines, drain electrodes, and source electrodes on the first substrate. Forming a pixel electrode so as to be connected to the drain electrode or the source electrode; forming a common electrode on a second substrate; and forming the pixel electrode between the first substrate and the second substrate. Sealing process with liquid crystal interposed between In the method of manufacturing a liquid crystal display device, the step of polycrystallizing the amorphous silicon detects whether or not the intensity of the transmitted light or the reflected light detected during the irradiation of the laser light is a predetermined value. Adjusting the energy received by the amorphous silicon from the laser light so that the intensity becomes the predetermined value when the intensity is not the predetermined value; and Irradiating the crystalline silicon. 12. The predetermined value is such that the detected transmittance of the transmitted light is 70% or less or the reflectance of the reflected light is 30%.
The method for manufacturing a liquid crystal display device according to claim 11, wherein the strength is not less than%. 13. The method for manufacturing a liquid crystal display device according to claim 11, wherein the inspection light is applied from the opposite direction to the irradiation of the laser light through the substrate. 14. The method according to claim 11, wherein the laser light and the inspection light are emitted from one light source. 15. The method as claimed in claim 15, wherein the step of adjusting the energy is performed by at least one of a method of increasing the energy of the laser light itself and a method of changing the number of times of irradiation of the substrate with the laser light. The method of manufacturing a semiconductor device according to claim 11. 16. A first laser light source for emitting a laser beam to an amorphous semiconductor film formed on an object to be processed to polycrystallize the amorphous semiconductor film, and the amorphous semiconductor film A second laser light source that emits inspection light that irradiates a portion irradiated by the laser light, and the light that is emitted from each of these laser light sources is introduced and the object to be processed is installed inside. A chamber; light intensity detecting means for detecting the intensity of transmitted light or reflected light from the irradiated part of the inspection light during irradiation of the laser light; and transmittance or reflectance obtained by detection by the light intensity detecting means. Determining means for determining the degree of crystallization of the amorphous semiconductor film based on the above, and scanning means for relatively scanning the object to be processed with the laser light and the inspection light. laser Neil apparatus. 17. The laser annealing apparatus according to claim 16, wherein the first laser device and the second laser device are arranged to face each other with the object to be processed interposed therebetween. 18. A laser light source for emitting a laser beam to an amorphous semiconductor film formed on an object to be processed to polycrystallize the amorphous semiconductor film, and each of the laser light sources emitted from the laser light source. A chamber in which light is introduced and the object to be processed is installed therein; light intensity detecting means for detecting the intensity of transmitted light or reflected light of the laser light during irradiation of the laser light; Determining means for determining the degree of crystallization of the amorphous semiconductor film based on the transmittance or reflectance obtained by the detection by the means; and the laser light and the inspection light relative to the workpiece A laser annealing device comprising: a scanning unit for performing scanning.