JP4667334B2 - Method for manufacturing semiconductor device - Google Patents

Description

  The invention disclosed in this specification relates to a method for manufacturing a semiconductor device by laser light irradiation with excellent mass productivity, small variation, and high yield, and a laser processing apparatus that can be used for the manufacturing method. In particular, the invention disclosed in this specification includes a semiconductor material that is partly or wholly made of an amorphous component, or a substantially intrinsic polycrystalline semiconductor material, as well as ion irradiation, ion implantation, ion doping, and the like. A method for improving the crystallinity of a semiconductor material by irradiating a semiconductor material that has been damaged by the laser beam and whose crystallinity has been significantly impaired, or for recovering the crystallinity, and a laser that can be used in these methods The present invention relates to a processing apparatus.

  In recent years, research has been actively conducted on lowering the temperature of semiconductor device processes. This is because a semiconductor element needs to be formed on an insulating substrate that is not so high in heat resistance such as glass. In addition, there is a demand accompanying miniaturization of elements and multilayering of elements.

  The superiority or inferiority of the characteristics of the element is determined by the crystallinity of the semiconductor material. Therefore, in a semiconductor process, an amorphous component contained in a semiconductor material or an amorphous semiconductor material is crystallized, or a crystal of a semiconductor material that has been crystallized but has crystallinity deteriorated due to ion irradiation. However, there is a need to improve the crystallinity.

  Conventionally, thermal annealing has been employed for such purposes. When silicon is used as a semiconductor material, annealing is performed at a temperature of 600 ° C. to 1100 ° C. for 0.1 to 48 hours, or longer, so that amorphous crystallization, crystallinity recovery, crystal The improvement of property is made.

  In general, the higher the temperature of thermal annealing, the shorter the processing time and the greater the crystallization effect. For this reason, since there is almost no effect at a temperature of 500 ° C. or lower, from the viewpoint of lowering the process temperature, it has been necessary to replace the steps conventionally performed by thermal annealing with other means.

  As a technique for changing the thermal annealing, a technique for performing annealing by irradiating a laser beam is attracting attention as a low temperature process. This is because laser light can be applied only to a place where high energy comparable to thermal annealing is required, and therefore laser annealing does not require the entire substrate to be exposed to a high temperature.

  Regarding the laser light irradiation, two methods are roughly classified. The first method is a method of irradiating a semiconductor material with a spot beam using a continuous wave laser such as an argon ion laser. When the semiconductor material is irradiated with a spot-like beam, the semiconductor material is melted and crystallized by being gradually solidified due to the difference in energy distribution within the beam and the movement of the beam.

  The second method uses a pulsed laser such as an excimer laser. The semiconductor material is crystallized by irradiating the semiconductor material with a laser pulse at a high energy density to instantaneously melt and solidify the semiconductor material.

However, in the first laser irradiation method, the maximum energy of the continuous wave laser is limited, so that the size of the beam spot is about several millimeters at most, so that the processing takes time. . On the other hand, in the second laser processing method, since the maximum energy of the laser is very large, it is possible to increase mass productivity by using a large spot (generally a square or rectangular beam pattern) of several cm ² or more. it can.

  However, in the case of a commonly used square or rectangular beam, it is necessary to scan the beam two-dimensionally in order to process a single large-area substrate, and there is still room for improvement in terms of mass productivity. It was.

  In this regard, since the beam is deformed into a linear shape and the length in the longitudinal direction of the beam exceeds the substrate to be processed, the beam only needs to be scanned in one dimension, so that the processing time can be shortened.

  The crystallization process by laser irradiation greatly affects the characteristics of a semiconductor device in which the intensity of laser energy is completed. Therefore, optimization of laser energy is one of the important issues.

  However, in the pulsed laser, the energy fluctuates to some extent for each pulse, and the degree of the fluctuation depends on the output energy. In particular, when the intensity of laser energy is too low, pulsed laser light has a tendency that the stability of the laser energy is remarkably lowered. When the optimum energy is in a region that significantly reduces the stability of laser oscillation, the uniformity of the laser irradiation surface is remarkably deteriorated. Therefore, it is difficult to irradiate the laser with uniform energy over the entire surface of the substrate. It cannot be uniformly crystallized.

  As a method to alleviate the non-uniformity of crystallinity of semiconductor materials, the uniformity of crystal growth can be improved by preliminarily irradiating a weaker pulsed laser beam before irradiating a strong pulsed laser beam. Has been reported. Furthermore, by making the beam scanning directions of the preliminary irradiation and the main irradiation substantially orthogonal to each other, the crystallinity non-uniformity caused by multiple irradiations is offset and the crystallinity of the entire substrate becomes more uniform. Has also been found. However, it does not fundamentally solve the crystallinity non-uniformity caused by the fluctuation of laser energy.

  In the method of irradiating the same substrate with laser with different energy, the energy of the laser beam must be changed for each irradiation. If the laser output is changed, the output of the pulsed laser becomes unstable for a while, so it is necessary to wait for the laser output to stabilize. Multiple laser irradiations have the advantage of improving the uniformity of crystallinity, but have the disadvantage of significantly increasing the processing time.

  An object of the present invention is to solve the above-described problems and provide a laser processing method capable of stably irradiating laser light with optimum energy even when irradiating laser light multiple times.

  Another object of the present invention is to provide a laser processing method that solves the above-described problems, stably irradiates laser light, and can perform laser light irradiation in a short time.

In order to solve the above problems, the configuration of the laser processing method according to the present invention is as follows.
In the process of irradiating the substrate on which the semiconductor device is formed or the substrate on which the object to be the semiconductor device is formed while scanning with a linear laser beam,
When laser irradiation is performed with energy lower than the energy range in which the laser can oscillate most stably, the energy adjustment is performed using one or more neutral density filters.

In addition, the other configuration of the laser processing method according to the present invention is as follows:
In the process of irradiating the silicon film formed on the substrate while scanning with a linear laser beam, when the laser irradiation is performed with an energy lower than the energy range in which the laser can oscillate most stably, a neutral density filter is used. The energy adjustment is performed by using one or more sheets.

Other configurations of the laser processing method according to the present invention include:
A method of irradiating a laser beam by adjusting the energy of a laser beam of a certain energy using one or more neutral density filters,
The type and / or the number of the neutral density filters to be used are changed at least once.

(Function)
The laser processing method according to the present invention having the above-described configuration outputs a laser with energy that oscillates stably, and uses a combination of at least one neutral density filter to adjust the laser energy to the optimum energy, Irradiate the substrate. In particular, this is effective when the energy to be irradiated is lower than the output energy of the laser beam. Needless to say, this filter need not be used when the substrate can be stably irradiated with the optimum energy without using a neutral density filter.

  Furthermore, the invention disclosed in this specification is a method of changing laser energy for each irradiation when the laser irradiation is performed a plurality of times on the same substrate (for example, a method of performing the preliminary irradiation and the main irradiation twice described above). ) Is more effective. That is, the laser energy is optimized only by changing the type and / or number of neutral density filters for each irradiation without changing the laser output. For this reason, since laser irradiation can be performed a plurality of times while maintaining a stable laser output, time for stabilizing the laser can be omitted. For this reason, the processing time can be shortened.

  When laser irradiation is performed a plurality of times, scanning is performed while reciprocating the laser beam relative to the substrate. At this time, it is preferable that the scanning direction of the laser beam is substantially perpendicular in the forward path and the backward path. For this reason, it is possible to uniformly irradiate the laser with a very lean operation and to shorten the time required for the laser irradiation. In the case of performing laser irradiation a plurality of times, the neutral density filter may be quickly inserted into and removed from the laser beam path when the forward or return path of the laser beam scanning is completed.

  The effects obtained by adopting the configuration described above are not limited to energy adjustment by simply combining a laser and a neutral density filter, but can be any energy lower than the maximum energy that the pulsed laser to be used can provide stably. Thus, it refers to the effect that laser irradiation can be performed stably and the effect that laser irradiation can be performed continuously without changing the laser output when performing laser irradiation multiple times with different energy as described above.

  In the laser processing step according to the present invention, the laser irradiation energy is adjusted by the neutral density filter, so that the laser output can be kept constant throughout. For this reason, even if the pulsed laser to be used outputs with stable energy, the laser can be stably irradiated with any energy lower than this energy, so that the uniformity of the film to be a semiconductor device can be improved. . Furthermore, even when the laser irradiation is performed a plurality of times, it is not necessary to change the laser output, so that the time for stabilizing the laser can be saved. In particular, when mass production is performed, it has a great effect on improving work efficiency and reducing costs.

  The invention disclosed herein can be used in all laser processing processes used in semiconductor device processes. In particular, when the present invention is applied to a TFT as a semiconductor device, an excellent crystalline silicon film can be obtained, for example, by applying the laser treatment process of the present invention to a crystallization process. The uniformity of the value voltage can be improved. Alternatively, the field effect mobility of the TFT or the uniformity of the on-current can be improved by applying the laser treatment process of the present invention to the source / drain impurity element activation process. Thus, the present invention is considered industrially useful.

  In the process of increasing the crystallinity of this film by irradiating a laser beam to a silicon film or silicon compound film in an amorphous state or crystallinity, the homogeneity of the film surface tends to decrease. A method for suppressing the reduction as much as possible is shown in this embodiment, and further, it is described that the working time of laser irradiation can be greatly shortened by using this method.

  FIG. 1 shows a configuration diagram of a laser annealing apparatus used in this embodiment. On the base 1, an oscillator 2 that oscillates laser light is disposed. Total reflection mirrors 5 and 6 are arranged on the optical path in the emission direction of the oscillator 2, and on the optical path in the reflection direction of the total reflection mirror 6, the amplifier 3, total reflection mirrors 7 and 8, the optical system 4, and total reflection. The mirrors 9 are arranged in sequence. On the optical path bent downward by the total reflection mirror 9, a stage 10 for placing the sample 11 is disposed.

  The stage 10 is controlled by a computer so that it can reciprocate in a one-dimensional direction and can rotate within the surface of the stage 10. The stage 10 has a built-in heater so that the sample 11 can be maintained at a predetermined temperature.

  Further, although not shown in FIG. 1, a neutral density filter is detachably disposed between the total reflection mirror 8 and the optical system 4. FIG. 3 shows the structure of the drive mechanism of the neutral density filter. The light-reducing filters 31 to 34 can be moved along the rails 35 to 38 by remote operation, and can be inserted and removed from the optical path by this linear movement. The neutral density filters 31 to 34 have different transmittances, and by combining them, 15 different attenuation levels can be obtained. In this embodiment, the transmittances of the neutral density filters 31 to 34 are 96%, 92%, 85%, and 77%, respectively. By combining these four neutral density filters 31 to 34, an area with a transmittance of 57 to 96% can be substantially covered. For example, a neutral density filter having a transmittance of 88% can be obtained by combining the neutral density filter 31 having a transmittance of 96% and the neutral density filter 32 having a transmittance of 92%.

  The neutral density filters 31 to 34 are obtained by alternately coating hafnium oxide and silicon dioxide in layers on quartz, and the transmittance of the neutral density filters 31 to 34 depends on the number of coated layers.

  Laser light is oscillated by an oscillator 2. The laser light oscillated by the oscillator 2 is a KrF excimer laser (wavelength 248 nm, pulse width 25 ns). Of course, other excimer lasers and other types of lasers can also be used.

The laser light oscillated by the oscillator 2 is amplified by the amplifier 3 via the total reflection mirrors 5 and 6, is reflected by the total reflection mirrors 7 and 8, and enters the optical system 4.

  FIG. 2 is an optical arrangement diagram inside the optical system 4. The laser light incident on the optical system 4 passes through the cylindrical concave lens A, the cylindrical convex lens B, and the lateral fly-eye lenses C and D, so that the laser light is It changes from the previous Gaussian distribution type to the short distribution. Further, it passes through the cylindrical convex lenses E and F, is reflected by the mirror G (corresponding to the mirror 9 in FIG. 1), is focused by the cylindrical lens H, is formed into a linear beam, and is irradiated onto the sample 11.

The laser beam immediately before entering the optical system 4 has a rectangular shape of about 3 × 2 cm ² , but is processed into an elongated linear beam having a length of about 10 to 30 cm and a width of about 0.1 to 1 cm by the optical system 4. The energy of the laser beam that has passed through the optical system 4 is 1000 mJ / shot at the maximum.

  The reason why the laser beam is processed into such an elongated beam is to improve the processability. The linear beam is emitted from the optical system 4 and then irradiates the sample 11 through the total reflection mirror 9. Since the width of the beam is longer than the width of the sample 11, the sample 11 is moved in one direction. Thus, the entire sample 11 can be irradiated with laser light. Therefore, the structure of the driving device 10 of the stage 10 can be simplified, and maintenance is facilitated. In addition, alignment when fixing the sample 11 is facilitated.

  Hereinafter, an example in which a crystalline silicon film is formed over a glass substrate by laser light irradiation will be described. A 10 cm square glass substrate (for example, Corning 7959 glass substrate) is prepared. A silicon oxide film having a thickness of 2000 mm is formed on this glass substrate by plasma CVD using TEOS as a raw material. This silicon oxide film functions as a base film for preventing impurities from diffusing into the semiconductor film from the glass substrate side.

  Next, an amorphous silicon film is formed to a thickness of 500 mm by plasma CVD. Here, a plasma CVD method is used, but a low pressure thermal CVD method may be used. The thickness of the amorphous silicon film may be a required thickness.

  Next, the substrate is immersed in perhydro ammonia and kept at 70 ° C. for 5 minutes, thereby forming an oxide film on the surface of the amorphous silicon film. Thereafter, liquid phase nickel acetate is applied to the surface of the amorphous silicon film by spin coating. The nickel element functions as a catalyst for promoting crystallization when the amorphous silicon film is crystallized. The oxide film works to improve the adhesion of the nickel solution.

  Next, hydrogen in the amorphous silicon film is released by heating in a nitrogen atmosphere at a temperature of 450 ° C. for 1 hour. This is because the threshold energy for subsequent crystallization is lowered by intentionally forming a dangling bond in the amorphous silicon film. Further, the amorphous silicon film is crystallized by performing a heat treatment at 550 ° C. for 4 hours in a nitrogen atmosphere. The reason why the crystallization temperature can be lowered to 550 ° C. is due to the catalytic action of nickel element.

Thus, a crystalline silicon film can be obtained on the glass substrate. Further, this silicon film is irradiated with laser light to further enhance crystallinity.

  In order to irradiate the laser beam, the apparatus shown in FIG. 1 is used to irradiate a KrF excimer laser (wavelength 248 nm, pulse width 25 ns). Irradiation is performed in the atmosphere without any particular atmosphere control.

  The substrate placed on the stage 10 is kept at a temperature of 400 ° C. by a heater inside the stage 10. This is to mitigate the rate of rise and fall of the substrate surface temperature during laser irradiation. In general, it is known that rapid changes in the environment damage the homogeneity of materials. For this reason, the substrate temperature is kept high and constant during laser irradiation, and the deterioration of the uniformity of the substrate surface is suppressed as much as possible. Although the substrate temperature is set to 400 ° C., an optimum temperature for laser annealing can be selected in the range of 100 ° C. to 600 ° C.

  The laser light oscillated by the oscillator 2 is shaped into a linear beam in the optical system 4 and irradiated onto the substrate on the stage 10. The beam area at the irradiated portion is set to 125 mm × 1 mm. Since the size of the substrate is 10 cm × 10 cm, the laser beam is irradiated onto the entire surface of the substrate by linearly moving the stage 10 in a direction perpendicular to the longitudinal direction of the laser beam. The moving speed of the stage 10 is 2 mm / s.

  In order to crystallize the silicon film, first, laser irradiation is performed with low energy as preliminary irradiation, and then laser irradiation is performed with high energy as main irradiation. The reason why laser irradiation is performed in two stages is to suppress deterioration of the uniformity of the film surface due to laser irradiation as much as possible. The crystalline silicon film obtained by the above process has a lot of amorphous portions, and the absorption rate of laser energy is considerably different from that of polycrystalline silicon. Crystallize the crystalline part. The second main irradiation promotes crystallization as a whole. As a result, the crystallinity of the silicon film becomes uniform, and the characteristics of the semiconductor semiconductor device are remarkably improved. Further, in order to improve the uniformity, it is preferable to rotate the stage 10 by 90 degrees in the preliminary irradiation and the main irradiation so that the beam scanning directions are substantially orthogonal. Note that the rotation angle of the stage 10 is not limited to 90 degrees, and in general, the scanning direction of the linear laser is performed by rotating the stage 10 (n / 2 + 1/4) (n is a natural number including 0). Can be approximately orthogonal.

In this embodiment, laser annealing is performed with the pre-irradiation energy set to 200 mJ / cm ² and the main irradiation energy set to 300 mJ / cm ² . The output energy of the laser is 300 mJ / cm ² . This energy is in a range where the laser is stably output.

In the preliminary irradiation, the apparatus shown in FIG. 3 is used to insert a neutral density filter having a transmittance of 85% and 77% into the optical path of the laser to attenuate the intensity of the laser beam to 200 mJ / cm ² . Next, in the main irradiation, these neutral density filters are retracted from the laser light path, and laser irradiation is performed without attenuating energy.

Needless to say, when the energy of the main irradiation is lower than the energy region where the laser is stably output, the neutral density filter is used also during the main irradiation. For example, let us consider a case where laser irradiation is performed with an energy range in which the laser can be stably irradiated at 250 mJ / cm ² or more, pre-irradiation energy of 170 mJ / cm ² , and main irradiation energy of 220 mJ / cm ² . In this case, the laser output is fixed at, for example, 300 mJ / cm ² . During preliminary irradiation, insert all four neutral density filters into the optical path. At the time of the main irradiation, the neutral density filter having the transmittance of 92% and 85% is withdrawn from the optical path, and the neutral density filter having the transmittance of 96% and 77% is inserted in the optical path. By this. Laser can be irradiated with the required energy.

  In this embodiment, the laser irradiation energy can be changed by simply inserting and removing the neutral density filter from the optical path without changing the laser output. Irradiation energy can be set arbitrarily. Therefore, substrates on which films having different properties are formed can be processed in a lump.

  In a series of laser processing steps, the number of irradiations, irradiation energy, and the like are set for each substrate and stored in the controller of the laser apparatus shown in FIG. Place the substrate on the stage and align. After the alignment is completed, the controller irradiates the same substrate with the laser a plurality of times while reciprocating the stage 10. During this time, the output of the laser is kept constant, and whenever the laser irradiation is performed on the substrate in the forward and backward stages of the stage 10, the controller appropriately inserts and removes the neutral density filter into the laser optical path according to the input data, Adjust the irradiation energy. Further, while the trajectory of the stage 10 changes from the forward path to the return path or from the return path to the forward path again, the stage 10 is rotated at a substantially right angle to make the beam scanning direction orthogonal to the forward path and the return path. Thereby, since a laser is uniformly irradiated to a board | substrate, film quality can be made more uniform.

  The laser processing technology for the silicon film or silicon compound film described in Example 1 is carried out by an industrial machine with mass productivity (multi-chambered and the substrate is transported by a robot arm), and the substrate during laser irradiation A method for improving the homogeneity between the substrates by adjusting the atmosphere will be described.

  First, the apparatus will be briefly described. FIG. 4 is a structural view seen from the upper surface of the apparatus, and FIG. 5 is a cross-sectional view of the apparatus cut along A-A 'in FIG. The chamber 41 is a laser irradiation chamber. A heater is embedded under the place where the substrate is placed, so that the substrate can be maintained at a predetermined temperature during laser irradiation. The chamber 42 is a heating chamber in which a hot plate for heating the substrate is disposed. The chamber 43 is a spare chamber for stocking the substrate before laser irradiation, and the substrate can be loaded and unloaded through the spare chamber 43. That is, the substrate is carried into the apparatus from the spare chamber 43 and the substrate is carried out from the spare chamber 43 to the outside of the apparatus.

  The substrate carry-in chamber 40 in the center of the figure is provided with a robot arm 44 for carrying the substrate, and is used for moving the substrate between the chambers 41 to 43. Further, these chambers 41 to 43 have a sealing property and are designed so that the atmosphere can be controlled. Further, gate valves 45 to 47 are provided for partitioning the rooms. By closing the gate valves 45 to 47, mixing of the atmosphere between the rooms 41 to 43 can be prevented. Each of the chambers 41 to 43 is individually provided with an evacuation device, and is configured to perform evacuation to a required pressure.

  Reference numeral 55 denotes a laser oscillation device having a configuration as shown in FIG. 1 and a built-in neutral density filter system as shown in FIG. It can be inserted and removed to attenuate the laser energy to the size that should be irradiated.

  Next, a method for using the apparatus will be described. First, a plurality of substrates on which a thin film to be irradiated with laser light is formed are stored in a cartridge, and the entire cartridge is carried into the spare chamber 43. Then, all four chambers 40-43 are evacuated.

  Since laser processing in vacuum is not affected by gas, reproducibility of laser processing is improved. Alternatively, the method of maintaining reproducibility by always maintaining the laser processing chamber in a constant atmosphere produces the same effect as irradiation in a vacuum. This effect is useful for suppressing the variation of the product and increasing the reliability of the product, particularly in mass production.

  Then, the gate valves 45 and 47 are opened, and the substrates are transferred to the heating chamber 42 one by one using the robot arm 44 disposed in the substrate loading chamber 40. The substrate transferred to the heating chamber 42 is placed on a hot plate and heated to a predetermined temperature.

  The heating temperature of the substrate is 200 ° C. During this time, closing the gate valve 47 is preferable from the viewpoint of preventing impurity contamination, but it is disadvantageous from the viewpoint of productivity. Whether or not to close the gate valve 47 may be appropriately selected in the implementation. When the substrate is sufficiently warmed, the robot arm 44 carries the substrate to the laser irradiation chamber 41. In the laser irradiation chamber 41, laser irradiation is performed twice as preliminary irradiation and main irradiation under the same conditions as in the first embodiment.

  Since the size of the substrate is 10 cm × 10 cm, the area of the laser beam on the irradiated surface is 125 mm × 1 mm, and the moving speed of the stage is 2 mm / s, the time required for two laser irradiations is 100 A little over a second. In the heating chamber 42, the time for the substrate to warm up is about 3 minutes. Therefore, it is more efficient if the number of substrates that are twice the number of substrates that are irradiated with laser at a time is heated in the heating chamber 42 at a time.

  A predetermined number of substrates are heated in the heating chamber 42 in advance. After the heating, half of the substrates are first transported from the heating chamber 42 to the laser irradiation chamber 41 and irradiated with a laser. The substrate to be heated is replenished from the preliminary chamber 43 to the heating chamber 42 during the laser irradiation. After the laser irradiation is completed, the laser-treated substrate is returned from the laser irradiation chamber 41 to the spare chamber 43, and the remaining half of the first loaded substrates are transferred from the heating chamber 42 to the laser irradiation chamber 41. Irradiate. After the laser irradiation is completed, the heating of the substrate replenished from the preliminary chamber 43 is completed in the heating chamber 42. Therefore, by repeating the above operation continuously, the time for warming the substrate before laser irradiation can be saved, so that the processing time is shortened.

  In one laser treatment, the time for warming the substrate is 3 minutes and the laser irradiation time is 100 seconds. Therefore, a total of about 5 minutes is required. However, using the apparatus shown in FIGS. It becomes possible to suppress to. In addition, since all the substrates to be processed can be stored in the preliminary chamber 43 in advance, the atmosphere in the laser irradiation chamber 41 is not contaminated from the outside, so that laser annealing is continuously performed in a clean atmosphere (including a vacuum state). Can be done continuously.

It is a block diagram of the laser irradiation apparatus of Example 1. It is an arrangement view of an optical system for making laser light into a beam shape. It is a figure which shows the schematic structure of a neutral density filter. It is a top view of the laser processing apparatus of Example 2. It is a side view of the laser processing apparatus of Example 2.

Explanation of symbols

2 Laser oscillator 5, 6 Total reflection mirror 3 Amplifier 4 Optical system 7, 8 Total reflection mirror 31-34 Dimming lens 10 Stage 40 Substrate transfer chamber 41 Laser irradiation chamber 42 Heating chamber 43 Preparatory chamber 44 Robot arm 45-47 Gate valve 55 Laser oscillator

Claims (5)

A method of manufacturing a semiconductor device that irradiates a semiconductor film on a substrate while scanning linear laser light,
The length of the laser beam in the longitudinal direction is a length exceeding the substrate,
By inserting a first neutral density filter on the optical path of the laser beam, the energy of the laser beam is adjusted, the laser beam is scanned relative to the substrate, and the semiconductor film is irradiated. 1 laser light irradiation,
Removing the first neutral density filter from the optical path of the laser beam and inserting a second neutral density filter on the optical path of the laser beam to adjust the energy of the laser beam; Scanning the laser beam in a direction that is different from the laser beam irradiation energy in the laser beam irradiation in a direction that is relatively perpendicular to the scanning direction of the first laser beam irradiation relative to the substrate, and A method for manufacturing a semiconductor device, wherein the semiconductor film is crystallized by irradiating the semiconductor film with a second laser beam. A method of manufacturing a semiconductor device that irradiates a semiconductor film on a substrate while scanning linear laser light,
The length of the laser beam in the longitudinal direction is a length exceeding the substrate,
By inserting a first neutral density filter on the optical path of the laser beam, the energy of the laser beam is adjusted, the laser beam is scanned relative to the substrate, and the semiconductor film is irradiated. 1 laser light irradiation,
Removing the first neutral density filter from the optical path of the laser beam and inserting a second neutral density filter on the optical path of the laser beam to adjust the energy of the laser beam; The semiconductor is scanned with a higher energy than the laser beam irradiation energy in the laser beam irradiation in a direction that is relatively perpendicular to the scanning direction of the first laser beam irradiation relative to the substrate. A method for manufacturing a semiconductor device, wherein the semiconductor film is crystallized by irradiating the film with a second laser beam. In claim 1 or claim 2,
The method of manufacturing a semiconductor device, wherein the laser beam is an excimer laser. In any one of Claim 1 thru | or 3,
A method for manufacturing a semiconductor device, wherein the first laser light irradiation and the second laser light irradiation are performed in a room maintained in a constant atmosphere. In any one of Claims 1 thru | or 4,
A method for manufacturing a semiconductor device, wherein the first laser light irradiation and the second laser light irradiation are performed in a chamber kept in a vacuum.

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