JP5127111B2 - Manufacturing method of semiconductor substrate - Google Patents

Description

The present invention is an irradiated film formed on a substrate, for example, a laser having a laser beam irradiation energy density that is more determined in determining how the irradiation energy density of the irradiation of the semiconductor film such as amorphous Si film It relates to the production how the semiconductor substrate to perform the laser annealing using light.

  Laser light is coherent light and has excellent convergence, and thus is used in various processing fields such as welding, cutting, and surface treatment. In one of the processing fields using laser light, for example, an amorphous silicon (amorphous silicon, a-Si) film formed on a substrate is irradiated with laser light and heated to form a polycrystalline Si film. There is a laser annealing process. In this laser annealing treatment, an amorphous Si film is irradiated with laser light, whereby the a-Si film is converted into a polycrystalline Si film through the process of heating and melting and solidifying Si.

  Thin-film transistor (TFT) elements using a polycrystalline Si film as a transistor active layer are used in high-performance semiconductor integrated circuits such as switching elements, shift registers, and digital / analog (D / A) converter circuits in liquid crystal display devices. Has been. If the Si film formed on the substrate is an amorphous Si film, the carrier mobility is too low for it to constitute a transistor active layer, and the integration requires high speed and high performance. Use in circuits is difficult. Therefore, in order to improve the crystallinity of the Si film, the amorphous Si film formed on the substrate is subjected to a laser annealing treatment, that is, the amorphous Si film is irradiated with laser light to be melted and solidified. A method of forming a polycrystalline Si film by crystallization through the process is used.

  In such a method of forming a polycrystalline Si film by laser annealing, the crystallinity of the obtained polycrystalline Si film is greatly affected by the irradiation energy density of the laser light applied to the amorphous Si film. When the laser beam irradiation energy density is too low, crystal growth does not proceed sufficiently, and many amorphous Si portions remain in the Si film, so that the characteristics of the obtained polycrystalline Si film become very low. On the other hand, when the laser beam irradiation energy density is too high, the amorphous Si film is microcrystallized, which is an aggregate of fine crystals with a grain size of several to several tens of nanometers called microcrystal grains, The characteristics of the obtained polycrystalline Si film are deteriorated. That is, when crystallizing an amorphous Si film by a laser annealing method, the higher the irradiation energy density of the irradiated laser light, the higher the crystallinity of the resulting Si film, but if the irradiation energy density is too high, The obtained Si film is microcrystallized and its crystallinity is drastically lowered. Therefore, when crystallizing an amorphous Si film by the laser annealing method, the highest irradiation energy density is set as a threshold within the range where the crystallinity does not drop rapidly, and the irradiation energy density is set as high as possible below the threshold. Is desirable.

  However, in practice, the threshold value greatly varies depending on the laser beam shape, the transmittance of the optical system, the film thickness of the amorphous Si film, and the like. Therefore, when a polycrystalline Si film is manufactured by using the laser annealing method, first, a threshold value is determined using a part or the whole of the substrate for each substrate or for every several tens to several hundreds. Furthermore, a laser light oscillator that oscillates laser light does not always oscillate laser light having an energy density as set. That is, the laser oscillator oscillates a laser beam having a higher or lower energy density than a set energy density in a width called an apparatus margin. If the set value is set to a threshold value, the semiconductor film may be irradiated with laser light having an energy density higher than the threshold value. In such a case, the semiconductor film is microcrystallized and the characteristics of the semiconductor film are rapidly deteriorated. End up. Therefore, a method is used in which an energy density lower than the threshold value by an error width by the laser oscillator with respect to the irradiation energy density of the irradiated laser light is set as a processing condition of the laser annealing method.

  As a method for determining this threshold value, a method is adopted in which selection is made by visual judgment of the pre-irradiation portion on the amorphous Si film by the operator and crystallinity judgment based on half-value width analysis of the Raman spectrum obtained by Raman spectroscopic measurement. It was. However, the visual judgment largely depends on the experience and intuition of the operator and is not objective.Therefore, not only the selected value differs depending on the operator, but also the selected value for each day depending on the physical condition of the same operator. The judgment criteria are not stable. In addition, half-width analysis requires a long time for data processing and analysis, so it is not suitable for real-time feedback to laser annealing conditions for substrates during the manufacturing process, and confirms crystallinity after laser annealing. It was only used for.

  The conventional technique as described above is described in Patent Document 1. In the laser annealing method of Patent Document 1, the thickness of the film to be annealed formed on the substrate is measured for each substrate with an ellipsometer, and the film to be annealed whose film thickness is measured is irradiated with laser light having various irradiation energies. After that, the crystallization state is measured by microscopic Raman spectroscopic analysis, and based on the irradiation energy of the laser light applied to the portion where the optimum crystallization state is obtained, the irradiation energy suitable for crystallizing the film to be annealed is obtained. It is a method of determination. Since the crystallization state of the film to be annealed after irradiation depends on the film thickness, a suitable irradiation energy based on the film thickness of the film to be annealed can be determined. However, both the measurement of the crystallization state by micro-Raman spectroscopy and the measurement of the film thickness by an ellipsometer require a long time, so that determining the laser beam irradiation energy during the manufacturing process results in poor productivity.

  Another conventional technique is described in Patent Document 2. In the method of manufacturing a semiconductor device disclosed in Patent Document 2, after laser irradiation is performed on an amorphous silicon film under various trial conditions, a portion irradiated with the laser beam is irradiated by analyzing a dark field image using an optical microscope. In this method, the laser light irradiation conditions are determined, and the amorphous silicon film is irradiated with a laser beam under the irradiation conditions. Since the analysis of the dark field image by the optical microscope is sensitive to the surface properties, the crystalline state of the amorphous silicon film can be measured, and the suitable irradiation condition of the laser beam can be determined based on the crystalline state. However, since the analysis of the dark field image by the optical microscope takes a long time, if the irradiation condition of the laser beam is determined during the manufacturing process, the productivity is deteriorated.

  A typical conventional technique for solving these problems is described in Patent Document 3. In the method of manufacturing a semiconductor film disclosed in Patent Document 3, the semiconductor film on the substrate is not microcrystallized for each substrate based on the scattered light intensity on the surface of the semiconductor film after the semiconductor film on the substrate is irradiated with energy light (laser light). In this method, the maximum energy density is determined as a threshold value, and the semiconductor film is irradiated with energy light having an energy density lower than the threshold value by a certain value.

  As another conventional technique, a technique similar to the technique of Patent Document 3 is described in Patent Document 4. In the method of manufacturing a liquid crystal display device disclosed in Patent Document 4, an amorphous semiconductor formed on the surface of a substrate is irradiated with an excimer laser to perform annealing in a reaction vessel, thereby polycrystallizing the amorphous semiconductor. In this case, the amorphous semiconductor is irradiated with inspection light and the scattered light is detected by a detector, and the annealing is performed several times until the desired crystallinity is obtained while evaluating the crystallinity.

Japanese Patent Laid-Open No. 10-284433 Japanese Patent Laid-Open No. 2002-8976 JP 2000-114174 A JP 2002-9012 A

  In order to efficiently obtain a semiconductor film with high crystallinity, it is necessary to be able to easily determine the optimum irradiation energy density of the laser light with which the semiconductor film is irradiated.

  According to the method for manufacturing a semiconductor device disclosed in Patent Document 3, the threshold for microcrystallization is determined, and the semiconductor film is irradiated with laser light having an energy density lower than the threshold by a certain value. High crystallinity can be achieved without crystallization.

  Below, the manufacturing method of the semiconductor device currently disclosed by patent document 3 is demonstrated in detail. First, by irradiating a semiconductor film formed on the substrate with laser light having various energy densities and measuring the scattered light intensity on the surface of the semiconductor film, the energy density and surface scattered light intensity of the irradiated laser light A graph showing the relationship can be obtained.

FIG. 6 is an example of a graph showing the relationship between the energy density of the laser beam to be irradiated and the surface scattered light intensity. The horizontal axis represents the energy density (mJ / cm ² ) of the laser light applied to the semiconductor film, and the vertical axis represents the surface scattered light intensity. Line 31 is a characteristic curve of the energy density of the laser beam to be irradiated and the surface scattered light intensity. As can be seen from the figure, as the energy density increases, the surface scattered light intensity increases. That is, an increase in the intensity of the surface scattered light represents an improvement in the crystallinity of the semiconductor film. Therefore, when the energy density of the irradiated laser light increases, the obtained semiconductor film has a high crystallinity. However, if it is higher than the threshold value of about 360 mJ / cm ² , the semiconductor film is microcrystallized, and the surface scattered light intensity rapidly decreases. Therefore, a laser beam having an energy density that is a threshold is most preferable for manufacturing a semiconductor film. However, since the laser oscillator has a margin, a set value of the energy density of the laser beam is indicated by an arrow 33 from the threshold. The energy density is set to about 345 mJ / cm ² , which is lower by the device margin of about 15 mJ / cm ² . By doing so, it is possible to irradiate the semiconductor film with a laser beam having an energy density as high as possible within a range not higher than the threshold, and thus the obtained semiconductor film. Is preferable because of high crystallinity without microcrystallization.

  However, in practice, after processing a predetermined number of substrates or oscillating a laser beam a predetermined number of times, the laser gas in the laser oscillator deteriorates, and it is essential to replace the laser gas with a new gas. It is. When the laser gas is exchanged, the laser oscillator state slightly changes, so that the characteristic curve between the energy density of the irradiated laser light and the surface scattered light intensity changes.

FIG. 7 shows correspondence information between the energy density of the laser beam irradiated using the laser oscillator whose laser gas is exchanged and the surface scattered light intensity. Similar to FIG. 6, the horizontal axis represents the energy density (mJ / cm ² ) of the laser light applied to the semiconductor film, and the vertical axis represents the surface scattered light intensity. Line 41 is line 31 in FIG. 6, and is an example of a characteristic curve between the energy density of the irradiated laser beam and the surface scattered light intensity. Lines 42 and 43 are characteristic curves of energy density and surface scattered light intensity when the laser gas of the laser oscillator is exchanged. As can be seen from the figure, when the laser gas is exchanged and the state of the laser oscillator changes, the intensity of the surface scattered light when irradiated with the laser beam having the energy density that is the threshold value becomes substantially constant. The characteristic curve with the strength changes. Compared with the exchange of laser gas, the degree of energy density is small, but the energy density also depends on the film thickness of the amorphous Si film that is the film to be annealed, the deterioration of the laser gas over time and the optical system transmittance of the laser annealing apparatus. And the characteristic curve of the surface scattered light intensity may change.

Thus, the characteristic curve of the energy density and the surface scattered light intensity is changed, further, the threshold is, the case of line 41, about 360 mJ / cm ^2, when the line 42, about 350 mJ / cm ^2, if the line 43 Varies with about 340 mJ / cm ² . Even in such a case, it is determined as the energy density of the laser beam that irradiates the energy density lower than the respective threshold by about 15 mJ / cm ² that is the apparatus margin indicated by the arrow 44. The energy density thus determined can be set in each characteristic curve because it can be set in a range where the energy density is not higher than the threshold value. However, the scattered light intensity of the obtained semiconductor film is about 60 in the case of the line 41. In the case of the line 42, it becomes about 65, and in the case of the line 43, it becomes about 70, and the surface scattered light intensity of the semiconductor film varies. In other words, the characteristic curve between the energy density and the surface scattered light intensity changes due to the state of the laser oscillator changing when the laser gas is exchanged, etc. Since the energy density is set lower by a certain value, the crystallinity of the obtained semiconductor film varies. Such a variation causes a large variation in TFT element characteristics using the polycrystalline Si film, and a high-function circuit such as a drive circuit, a shift register, and a D / A converter constituted by the active element is designed. There is a danger of becoming a major obstacle.

  According to the method of manufacturing a liquid crystal display device disclosed in Patent Document 4, an amorphous semiconductor is irradiated with an excimer laser to perform an annealing treatment in a reaction vessel, and the amorphous semiconductor is irradiated with inspection light. By detecting the scattered light with a detector, the crystallinity of the amorphous semiconductor is evaluated, and annealing treatment is performed until the desired crystallinity is obtained, so that the obtained semiconductor has high crystallinity. Become. However, if the output of the excimer laser used in one annealing process is too large for the amorphous semiconductor, the crystallinity is remarkably deteriorated until the desired crystallinity is obtained. Further, if the output of the excimer laser used in one annealing process is small, the annealing process must be performed several times until the desired crystallinity is obtained, which takes time.

An object of the present invention is to increase the crystallinity of a film to be irradiated by irradiating laser light, so that the laser light does not cause variations in the crystallinity of the film to be obtained due to the influence of a change in the state of a laser oscillator. is to provide a manufacturing how the semiconductor substrate using the way of determining the irradiation energy density of.

The present invention also includes a preliminary irradiation step of irradiating the amorphous Si film formed on the substrate with laser beams having various irradiation energy densities;
A surface scattered light intensity measuring step for measuring the surface scattered light intensity of the amorphous Si film irradiated with laser light for each irradiation energy density;
A laser characteristic curve creating step of creating a laser characteristic curve from the correspondence between the irradiation energy density and the surface scattered light intensity;
A process condition determining step including an irradiation energy density determining step for determining an irradiation energy density at which a surface scattering light intensity set in advance as a target is obtained based on the laser characteristic curve ;
The laser beam with an energy density determined perform laser annealing process by irradiating the amorphous Si film, to have a laser annealing to form a polycrystalline Si film,
When a predetermined condition is satisfied, a process condition determining step is performed again to re-determine the irradiation energy density of the laser beam,
In the irradiation energy density determination step after the predetermined condition is satisfied, the process before the predetermined condition is satisfied based on the laser characteristic curve generated in the laser characteristic curve generation step after the predetermined condition is satisfied A method for manufacturing a semiconductor substrate, comprising: determining an irradiation energy density that is used in the irradiation energy density determination step in the condition determination step to obtain the surface scattering light intensity set in advance as a target .

  According to the present invention, the predetermined condition is that the laser gas of the laser oscillator is exchanged.

  In the invention, it is preferable that the predetermined condition is that one substrate is laser-annealed.

  In the invention, it is preferable that the predetermined condition is that a plurality of substrates are laser-annealed.

According to the present invention, the amorphous Si film formed on the substrate is irradiated with laser light having various irradiation energy densities, and the amorphous Si film is irradiated with the laser light for each irradiation energy density. By measuring the surface scattered light intensity, a laser characteristic curve is created from the correspondence between the irradiation energy density and the surface scattered light intensity. Based on the laser characteristic curve, an irradiation energy density that can obtain a surface scattered light intensity set in advance as a target is determined.

Based on the laser characteristic curve created by actually irradiating the laser beam in the preliminary irradiation process, the irradiation energy density for obtaining the surface scattering light intensity set in advance as a target is determined, so that the obtained polycrystalline Si film The variation in crystallinity can be reduced.
By irradiating the amorphous Si film with the laser beam having the irradiation energy intensity determined by the above method and performing the laser annealing treatment, the irradiation energy density according to the change in the characteristic curve can be determined. A polycrystalline Si film having a small variation in surface scattered light intensity, that is, a small variation in crystallinity can be formed.
Also, when a predetermined condition such as a change in the state of the laser oscillator is satisfied, the irradiation energy density of the laser beam is determined again by the above method, so that the surface scattered light intensity of the obtained polycrystalline Si film is It is possible to form a polycrystal Si film having a small variation around a preset target value and a small variation in crystallinity.

Further, according to the present invention, the irradiation energy density is re-determined by the above method every time the laser gas whose laser oscillator state changes most is changed, so that a polycrystalline Si film having a small variation in crystallinity can be efficiently formed. Can be obtained.

According to the present invention, the irradiation energy density is re-determined by the above method every time laser annealing is performed on a single substrate, so that it is possible to form a polycrystalline Si film with extremely small variation in crystallinity. In addition, it is possible to form a polycrystalline Si film having a small variation in crystallinity without being affected by various changes such as a change in the thickness of the amorphous Si film, a change in the laser beam shape and the transmittance of the optical system. .

In addition, according to the present invention, each time laser annealing is performed on a plurality of substrates, for example, when the state of the laser oscillator changes according to the characteristics of the laser oscillator, the irradiation energy density is determined again by the above method. Therefore, a polycrystalline Si film having a small variation in crystallinity can be efficiently obtained according to the characteristics of the laser oscillator.

  The present invention is characterized in a method of determining an irradiation energy density of laser light applied to a film to be irradiated in laser annealing, and re-determination is performed every time a predetermined condition is satisfied.

  FIG. 1 is a flowchart showing a method for manufacturing a semiconductor device according to a first embodiment of the present invention. Here, the predetermined condition is that the laser gas of the laser oscillator is exchanged, and the irradiated film is a semiconductor thin film formed on a substrate such as a semiconductor wafer or a glass substrate. When manufacturing is started, first, the process of step A1 is performed. In step A1, the irradiation energy density of the laser light irradiated to the semiconductor thin film is determined by a method described later. In step A2, laser annealing is performed on one substrate by irradiating the semiconductor thin film with laser light having the irradiation energy density determined in step A1. In step A3, when a CPU (Central Processing Unit) determines that there is a substrate to be subjected to laser annealing, the process proceeds to step A4. When the CPU determines that there is no substrate to be subjected to laser annealing, End of production. In step A4, when the CPU determines that the laser gas has been replaced, the process returns to A1 and the irradiation energy density is determined again. If the CPU determines that the laser gas has not been replaced, the process returns to A2, and laser annealing is performed on the next substrate.

  When the laser gas of the laser oscillator is changed, the state of the laser oscillator changes greatly, but the irradiation energy density of the laser beam to be irradiated is re-determined each time. By doing so, the irradiation energy density is determined when the state of the laser oscillator changes the most, so that laser annealing can be performed efficiently, and a film with a small variation in crystallinity of the irradiated film is obtained. be able to. Further, the irradiated film is specifically a semiconductor film formed on a Si wafer, a glass substrate, etc., in particular an amorphous Si film, and after treatment by the laser annealing method of the present invention, A poly-Si film with small variation in properties can be obtained.

  FIG. 2 is a flowchart showing a method for determining an irradiation energy density according to an embodiment of the present invention. First, in step B1, the irradiated film is irradiated with laser light having various irradiation energy densities. In step B2, the surface scattered light intensity of the irradiated film is measured for each irradiation energy. In step B3, correspondence information between the irradiation energy density and the surface scattered light intensity is created based on the irradiation energy density of the irradiated laser light and the measured surface scattered light intensity. The information is shown in FIG. In step B4, the irradiation energy density is determined from the surface scattered light intensity, which is a preset target value, based on correspondence information between the irradiation energy density and the surface scattered light intensity. Here, the correspondence relationship information may be, for example, a characteristic curve between the irradiation energy density and the surface scattered light intensity, or may be a relational expression between the irradiation energy density and the surface scattered light intensity. Hereinafter, the correspondence relationship information will be described as a characteristic curve. Note that the surface scattered light intensity, which is a target value, is input to a device to be described later and stored in a memory. Further, when there are a plurality of irradiation energy densities such that the surface scattered light intensity determined in step B4 becomes a target value, the lowest irradiation energy density is determined.

FIG. 3 is a characteristic curve of the laser beam irradiation energy density and the surface scattered light intensity. The horizontal axis represents the energy density (mJ / cm ² ) of the laser light applied to the semiconductor film, and the vertical axis represents the surface scattered light intensity. Lines 1, 2 and 3 are characteristic curves of the irradiation energy density of the laser beam to be irradiated and the surface scattered light intensity when the state of the laser oscillator is changed by exchanging the laser gas of the laser oscillator. As shown in FIG. 3, when the state of the laser oscillator changes, the surface scattered light intensity when irradiated with the irradiation energy density that is a threshold is substantially constant, but the characteristic curve between the irradiation energy density and the surface scattered light intensity is , Changes as lines 1, 2 and 3. For example, if the target value of the surface scattered light intensity and 60, the irradiation energy density in the case of line 1, from about 345mJ / cm ^2, the case of line 2, from about 330 mJ / cm ^2, the case of line 3, from about 315mJ / cm ² . When the laser beam having such an irradiation energy density is irradiated, the surface scattered light intensity of the irradiated film obtained is about 60 in all cases. The surface scattered light intensity on the vertical axis is a value that depends on the instrument to be measured, but under a certain condition, it is a value that reflects the crystallization state of the irradiated film. It can be seen that an irradiation film could be obtained.

  FIG. 4 is a system diagram showing a simplified configuration of the laser annealing apparatus 11 according to one embodiment of the present invention. The laser annealing apparatus 11 divides a laser oscillator 12 that emits laser light and an irradiated film 17 into a plurality of regions in a planar shape, and guides the laser light emitted from the laser oscillator 12 for each of the divided regions. At the same time, the irradiation optical system 13 capable of variably adjusting the amount of laser light for each region, the surface scattered light intensity measuring means 14 for measuring the surface scattered light intensity of the irradiated film for each region, and the irradiated film Based on the relationship between the irradiation energy density of the irradiated laser light and the output of the surface scattered light intensity measuring means 14, the oscillation output of the laser oscillator 12 or the amount of light of the irradiation optical system 13 is adjusted to thereby irradiate the laser light. And control means 15 for controlling the irradiation energy density for the film.

  The laser annealing apparatus 11 according to the present embodiment performs an annealing process by irradiating a laser beam to an amorphous Si film 17 that is an irradiated film formed on a glass substrate 16, for example. Used. A semiconductor substrate 21, which is a substrate 16 on which an amorphous Si film 17 is formed, is placed on an XY table 18 that can move in at least two axial directions. The XY table 18 includes a driving unit (not shown) and a control unit for the driving unit that can control the operation of the driving unit to move the substrate 16 on the table to a desired position. . The substrate 16 on which the amorphous Si film 17 is formed and the XY table 18 are accommodated in an internal space 20 of a processing chamber 19 that is a processing container.

  The processing chamber 19 is, for example, a metal box container. The processing chamber 19 is provided with a vacuum pump (not shown), its piping system, a supply source of inert gas or active gas, and its piping system, and an amorphous Si film in a vacuum atmosphere or any other gas atmosphere. The laser annealing process is possible.

  In this embodiment, the laser oscillator 12 that emits laser light oscillates an XeCl excimer laser using an excimer of a rare gas and a halide. The laser oscillator 12 is configured such that its oscillation output is variable by a control signal from the control means 15. In addition to the laser oscillator that oscillates the XeCl excimer laser, a laser oscillator that oscillates a KrF excimer laser, an ArF excimer laser, and other excimer lasers can also be used.

  The irradiation optical system 13 bends the optical path of the laser light emitted from the laser oscillator 12 and guides it to the amorphous Si film 17 in the processing chamber 19, and the light amount adjustment for variably adjusting the light amount of the laser light. And a member. In the present embodiment, a method of variably adjusting the light amount by attenuating the light amount of the laser light emitted from the laser oscillator 12 is employed. Therefore, in FIG. 4, the irradiation optical system 13 is represented by a light amount adjustment function. It is written as an attenuator that represents an attenuator. The light amount adjusting member (attenuator) provided in the irradiation optical system 13 includes (a) a plurality of partial transmission mirrors having different transmittances, and these partial mirrors are selected and inserted into the optical path. (B) the half mirror is provided in the optical path. Any one of the one that changes the angle between the half mirror and the laser beam and (c) the one that inserts the polarizing plate into the optical path and changes the direction of its polarization axis may be used.

  The surface scattered light intensity measuring means 14 irradiates the amorphous Si film 17 with a laser beam for measurement at a predetermined incident angle, and the amorphous Si film 17 is detected by a detector installed at an angle other than the angle corresponding to the incident angle. This is an apparatus capable of measuring the crystallization state of the amorphous Si film 17 by detecting the scattered light intensity on the surface of the film 17.

  The control means 15 is a processing circuit including a CPU, and is realized by, for example, a microcomputer. As the memory 21, for example, a known memory such as ROM (Read Only Memory) or RAM (Random Access Memory) can be used.

  The memory 21 stores the relationship between the irradiation energy density of the laser light applied to the amorphous Si film 17 and the surface scattered light intensity. Based on the relationship between the irradiation energy density and the surface scattered light intensity, the irradiation energy density of the laser beam to be irradiated is determined by the method for determining the irradiation energy density as described above. Further, the memory 21 stores the surface scattered light intensity inputted as the target value and the number of pieces subjected to laser annealing.

  Therefore, when this apparatus is used, an irradiated film with little variation in crystallinity can be formed.

  FIG. 5 is a flowchart showing a method for manufacturing a semiconductor device according to the second embodiment of the present invention. Here, unlike the first embodiment, the predetermined condition is not that the laser gas of the laser oscillator is replaced, but that a predetermined number of substrates are laser-annealed. The predetermined number is a plurality of sheets and is stored in the memory 21 in advance. When manufacturing is started, first, the process of step C1 is performed. In step C1, the irradiation energy density of the laser beam irradiated onto the film to be irradiated is determined by the above-described irradiation energy density determination method. In Step C2, the semiconductor thin film is irradiated with laser light having the irradiation energy density determined in Step C1, and one substrate is subjected to laser annealing. Also, the value of the number of processed sheets stored in the memory is incremented by one. In step C3, when the CPU determines that there is a substrate to be subjected to laser annealing, the process proceeds to step C4. When the CPU determines that there is no substrate to be subjected to laser annealing, the manufacturing of the semiconductor device is finished. . In step C4, the CPU compares the predetermined number with the processed number, and if the CPU determines that the predetermined number and the processed number are the same, the process returns to step C1. In step C1, the irradiation energy density is determined again, and the number of processed sheets stored in the memory is set to zero. If the CPU determines that the predetermined number is larger than the processed number, the process returns to step C2.

  Therefore, since the irradiation energy intensity is optimized when the state of the laser oscillator changes in accordance with the laser oscillator, it is possible to efficiently obtain a film to be irradiated with small variations in crystallinity.

  Further, the predetermined number may be one. In this case, the irradiation energy density is determined again for each substrate. By doing so, it is possible to obtain a film to be irradiated with extremely small variation in crystallinity.

  Note that when the irradiation energy density is determined after exchanging the laser gas or after processing a predetermined number of substrates, a part of the irradiated film on the substrate may be used or all of the film may be used. However, when the irradiation energy density determination method is performed for each substrate, it is necessary to use a part of the irradiated film on the substrate.

3 is a flowchart showing a method for manufacturing the semiconductor device according to the first embodiment of the present invention. It is a flowchart which shows the determination method of the irradiation energy density which is one Embodiment of this invention. This is correspondence information between the irradiation energy density of the irradiated laser beam and the surface scattered light intensity. It is a systematic diagram which simplifies and shows the structure of the laser annealing apparatus 11 which is one Embodiment of this invention. It is a flowchart which shows the manufacturing method of the semiconductor device which is the 2nd Embodiment of this invention. It is an example of the graph which shows the relationship between the energy density of the laser beam to irradiate, and surface scattered light intensity | strength. This is correspondence information between the energy density of the laser beam irradiated using the laser oscillator whose laser gas is exchanged and the surface scattered light intensity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Laser annealing apparatus 12 Laser oscillator 13 Irradiation optical system 14 Surface scattered light intensity measurement means 15 Control means 16 Substrate 17 Amorphous Si film 18 XY table 19 Processing chamber 20 Internal space 21 Memory 22 Semiconductor substrate

Claims (4)

A preliminary irradiation step of irradiating the amorphous Si film formed on the substrate with laser beams having various irradiation energy densities;
A surface scattered light intensity measuring step for measuring the surface scattered light intensity of the amorphous Si film irradiated with laser light for each irradiation energy density;
A laser characteristic curve creating step of creating a laser characteristic curve from the correspondence between the irradiation energy density and the surface scattered light intensity;
A process condition determining step including an irradiation energy density determining step for determining an irradiation energy density at which a surface scattering light intensity set in advance as a target is obtained based on the laser characteristic curve ;
A laser beam having an irradiation energy density determined perform laser annealing process by irradiating the amorphous Si film, to have a laser annealing to form a polycrystalline Si film,
When a predetermined condition is satisfied, a process condition determining step is performed again to re-determine the irradiation energy density of the laser beam,
In the irradiation energy density determination step after the predetermined condition is satisfied, the process before the predetermined condition is satisfied based on the laser characteristic curve generated in the laser characteristic curve generation step after the predetermined condition is satisfied A method for manufacturing a semiconductor substrate, comprising: determining an irradiation energy density at which the previously set target scattered light intensity used in the irradiation energy density determination step in the condition determination step is obtained . 2. The method of manufacturing a semiconductor substrate according to claim 1 , wherein the predetermined condition is that the laser gas of the laser oscillator is exchanged. 2. The method of manufacturing a semiconductor substrate according to claim 1 , wherein the predetermined condition is that one substrate is subjected to laser annealing. 2. The method of manufacturing a semiconductor substrate according to claim 1 , wherein the predetermined condition is that a plurality of substrates are laser-annealed.

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