JP2004179356A - Semiconductor device and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor device in which the unevenness of ON current, mobility or a threshold value of a TFT can be suppressed by suppressing the occurrence of the uneven state of the surface of a semiconductor film or crystallinity, and to provide the semiconductor device manufactured by using this manufacturing method. <P>SOLUTION: The method for manufacturing the semiconductor device includes the steps of adding a rare gas to the semiconductor film formed on the surface of an insulator by using an ion doping method, and irradiating the semiconductor film in which the rare gas is added with a laser beam of a pulse oscillation in a rare gas atmosphere. In the case of irradiating with the laser beam, a vibration by an ultrasonic wave may be imparted to the semiconductor film in which the rare gas is added. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a semiconductor device including a step of crystallizing a semiconductor film using laser light, and a semiconductor device manufactured using the method.
[0002]
[Prior art]
A thin film transistor using a polycrystalline semiconductor film (polycrystalline TFT) has a mobility that is at least two orders of magnitude higher than a TFT using an amorphous semiconductor film, and a pixel portion of a semiconductor display device and a peripheral driver circuit are formed on the same substrate. It has the advantage that it can be integrally formed on top.
[0003]
The polycrystalline semiconductor film can be formed over an inexpensive glass substrate by using a laser annealing method. However, the energy of the laser light output from the oscillator has at least several percent fluctuation due to various factors, and this fluctuation prevents uniform crystallization of the semiconductor film. If the crystallization is not performed uniformly and the crystallinity of the polycrystalline semiconductor film varies, the characteristics of a TFT using the polycrystalline semiconductor film as an active layer, such as on-current and mobility, vary.
[0004]
For example, in the case of an active matrix type light emitting device in which a light emitting element and a TFT for controlling current supply to the light emitting element are provided in each pixel, when the on current of the TFT varies, the light emitting element The brightness of the image also fluctuates accordingly.
[0005]
Further, when crystallization is performed by irradiating a laser beam in the air, the surface of the semiconductor film is slightly roughened. The roughening of the surface of the semiconductor film becomes more conspicuous as the intensity of the energy of the laser beam is higher. Since light is scattered and looks brighter in a region with a remarkably rough surface, stripe-like shading at several millimeter intervals due to energy fluctuation may be visually recognized.
[0006]
It is described in Patent Document 1 below that the surface state of the semiconductor film is closely related to oxygen in the atmosphere at the time of laser light irradiation.
[0007]
[Patent Document 1]
JP-A-2000-138180 (pages 3-4)
[0008]
Patent Document 1 describes that the greater the oxygen content in the atmosphere, the more the surface of the semiconductor film crystallized by laser light irradiation becomes significantly rougher. Describes that Ar is sprayed on a semiconductor film.
[0009]
When the surface of the semiconductor film becomes rough, the interface state density at the interface between the semiconductor film and the gate insulating film formed in contact with the semiconductor film increases, and the threshold voltage changes to a normally-off side. Therefore, when the state of the surface of the semiconductor film becomes uneven due to the fluctuation of the energy of the laser light, the interface state density at the interface with the gate insulating film to be formed later varies, and the threshold value of the TFT varies.
[0010]
[Problems to be solved by the invention]
In view of the above-described problems, the present invention provides a method for manufacturing a semiconductor device capable of suppressing unevenness in surface state and crystallinity of a semiconductor film and suppressing variations in TFT on-current, mobility, and threshold. It is an object to provide a semiconductor device manufactured using a manufacturing method.
[0011]
[Means for Solving the Problems]
It is assumed that there is a close inseparable relationship between the energy density of laser light and the crystallinity of the semiconductor film. However, the present inventors have considered that a variation in crystallinity that is so large that a variation in luminance can be visually recognized cannot be explained only by the cause of fluctuation in energy density of several percent. Thus, secondary factors that may be caused by fluctuations in energy density and that affect crystallinity were considered.
[0012]
The present inventors have paid attention to the incorporation of oxygen or nitrogen present in the atmosphere into a semiconductor film melted by laser light.
[0013]
FIG. 8A is a cross-sectional view of the semiconductor film 9000 when a pulsed laser beam is irradiated in air. It is considered that the region 9001 of the semiconductor film 9000 to which the laser light is irradiated is completely melted and in a liquid phase, or partially in a liquid phase without being completely melted. Since the melted silicon easily reacts with oxygen or nitrogen in air, an extremely thin insulating film 9003 such as silicon oxide, silicon nitride, or silicon nitride oxide is formed on the surface of the semiconductor film 9000.
[0014]
FIG. 8B is a cross-sectional view of the semiconductor film 9000 when laser light is scanned from the state illustrated in FIG. In the case of pulse oscillation, a region irradiated with laser light moves discontinuously. Then, in the process of scanning the entire surface of the semiconductor film with the laser light, as shown in FIG. 8B, the region 9001 irradiated with the laser light in FIG. 8A and the laser light irradiated in FIG. Regions 9002 partially overlap each other.
[0015]
In FIG. 8B, the region 9002 is melted by laser light irradiation. It is said that a semiconductor film that is instantaneously melted by laser irradiation recrystallizes at a relatively high rate of several tens of m / s for pulse oscillation and several cm / s for continuous oscillation. Is presumed to dissolve in the semiconductor film more than the solubility. Then, it is considered that impurities are likely to be mixed into the semiconductor film from the insulating film which is in contact with the semiconductor film at the time of laser light irradiation. This is particularly remarkable in the case of pulsed laser light having a high recrystallization speed.
[0016]
Therefore, it is considered that the insulating film 9003 formed over the surface of the region 9001 is melted at a portion overlapping with the region 9002 and is mixed into the region 9002 as a piece of silicon oxide, silicon nitride, silicon nitride oxide, or the like. Therefore, in the case of pulse oscillation, the thickness of the insulating film 9003 depends on the energy density of the laser light, and it is predicted that fluctuations in the energy density directly lead to variations in impurity concentration.
[0017]
Further, it is said that a semiconductor film melted instantaneously by irradiation with laser light is recrystallized at a relatively high speed of several tens m / s in pulse oscillation and several cm / s in continuous oscillation. Is presumed to dissolve in the semiconductor film more than the solubility in the thermal equilibrium state.
[0018]
The irradiation time of the laser light used for crystallization of the semiconductor film depends on the scanning speed, but is about several to several tens of nanoseconds for pulse oscillation, but is several to several tens of nanoseconds for continuous oscillation. Relatively long, on the order of microseconds. Therefore, continuous oscillation is considered to have a longer time in which the semiconductor film is melted than pulse oscillation, and it is considered that impurities in the air are more likely to be mixed into the semiconductor film.
[0019]
The higher the temperature of the semiconductor film is, the higher the solubility of the gas is, so that impurities in the air are more easily dissolved in the semiconductor film. Therefore, in the case of continuous oscillation, it is presumed that if a difference in temperature given to the semiconductor film occurs due to fluctuations in energy density, the concentration of impurities in the semiconductor film varies.
[0020]
Impurities such as oxygen and nitrogen mixed in from the atmosphere have a positive segregation coefficient in the melted semiconductor film, and thus are likely to segregate at grain boundaries during recrystallization. This phenomenon called grain boundary segregation is more likely to occur for impurities having a lower solid solubility. The segregated impurities such as oxygen and nitrogen are easily combined with silicon to form an insulator such as silicon oxide, silicon nitride oxide, or silicon nitride. The insulator segregated at the grain boundaries hinders the movement of carriers in the semiconductor film, and causes a decrease in mobility.
[0021]
Therefore, as described above, it is expected that the mechanism of mixing of impurities into the semiconductor film is different between pulse oscillation and continuous oscillation, but in any case, the variation in impurity concentration caused by the fluctuation of energy density is This is considered to be a cause of the variation in the mobility of the semiconductor film.
[0022]
Therefore, the present inventors tried to increase the crystallinity by doping the semiconductor film with Ar in an Ar atmosphere after doping the semiconductor film with Ar before crystallization by laser light irradiation. Note that the element to be doped is not limited to Ar, and may be any element belonging to Group 0 (a rare gas element). The irradiation with the laser beam does not necessarily have to be performed in an Ar atmosphere, and may be a Group 0 gas or a gas obtained by adding hydrogen to a Group 0 gas. Group 0 elements are most suitable in that they are neutral in the semiconductor film and do not serve as dopants, and are difficult to form compounds with elements constituting semiconductors such as silicon. In particular, since Ar is inexpensive, the cost for the manufacturing process of the semiconductor device can be reduced.
[0023]
The process from doping the semiconductor film with Ar to irradiating the semiconductor film with the laser light is performed, for example, in a load lock type chamber so as not to expose the semiconductor film to an atmosphere containing oxygen. For example, by using a multi-chamber manufacturing apparatus including a chamber for performing a process of forming a semiconductor film, a chamber for performing a process of doping Ar to the semiconductor film, and a chamber for irradiating the semiconductor film with laser light, A series of steps can be performed in sequence without exposing the film to the atmosphere.
[0024]
The mass of gas dissolved in a fixed volume of liquid is proportional to the partial pressure of the gas in contact with the liquid. Therefore, by doping Ar or the like in advance in the semiconductor film and irradiating the semiconductor film with a laser beam in an atmosphere of Ar or the like, it is possible to effectively prevent oxygen and nitrogen from entering the semiconductor film from the atmosphere. it can. In addition, when laser light irradiation is performed, an insulating film can be prevented from being formed on the surface of the semiconductor film, and a piece of the insulating film can be prevented from entering the semiconductor film.
[0025]
Therefore, variation in impurity concentration caused by fluctuation in energy density can be suppressed, and variation in mobility of the semiconductor film can be suppressed. In addition, in a TFT formed using the semiconductor film, variation in on-current as well as mobility can be suppressed.
[0026]
Further, by doping a rare gas element having a larger atomic radius than Si, such as Ar, the orientation of a semiconductor film crystallized by laser light can be increased.
[0027]
Further, as described in Patent Document 1, it has been known that the surface of a semiconductor film is roughened by irradiating a laser beam in an atmosphere in which oxygen exists according to an empirical rule. However, with the structure of the present invention, roughness of a semiconductor surface due to laser light irradiation can be suppressed, and variation in threshold value caused by variation in interface state density can be suppressed.
[0028]
Note that in the present invention, after the catalyst element is added to the semiconductor film, laser light irradiation may be performed to increase crystallinity.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
A method for manufacturing a semiconductor device of the present invention will be described with reference to FIGS.
[0030]
First, a base film 501 is formed over a substrate 500 as shown in FIG. As the substrate 500, for example, a glass substrate such as barium borosilicate glass or aluminoborosilicate glass, a quartz substrate, a SUS substrate, or the like can be used. A substrate made of a flexible synthetic resin such as plastic generally has a lower heat-resistant temperature than the above substrate, but any substrate can be used as long as it can withstand the processing temperature in the manufacturing process. It is.
[0031]
The base film 501 is provided to prevent an alkali metal such as Na or an alkaline earth metal contained in the substrate 500 from diffusing into the semiconductor film and adversely affecting characteristics of the semiconductor element. Therefore, the insulating film is formed using an insulating film of silicon oxide, silicon nitride, silicon nitride oxide, or the like which can suppress diffusion of an alkali metal or an alkaline earth metal into the semiconductor film. In this embodiment, a silicon nitride oxide film is formed with a thickness of 10 to 400 nm (preferably, 50 to 300 nm) by a plasma CVD method.
[0032]
Note that the base film 501 may be a single layer or a stack of a plurality of insulating films. In the case of using a substrate containing an alkali metal or an alkaline earth metal at all, such as a glass substrate, a SUS substrate, or a plastic substrate, it is effective to provide a base film from the viewpoint of preventing diffusion of impurities. However, when diffusion of impurities is not a problem, such as a quartz substrate, it is not always necessary to provide them.
[0033]
Next, a semiconductor film 502 is formed over the base film. The thickness of the semiconductor film 502 is 25 to 100 nm (preferably 30 to 60 nm). Note that the semiconductor film 502 may be an amorphous semiconductor or a polycrystalline semiconductor. As the semiconductor, not only silicon but also silicon germanium can be used. When silicon germanium is used, the concentration of germanium is preferably about 0.01 to 4.5 atomic%.
[0034]
Next, a Group 0 element is added to the semiconductor film 502 by an ion doping method. In this embodiment, an example in which Ar is used as an element of Group 0 will be described. He, Ne, Ar, Kr, Xe, and the like are typically given as Group 0 elements to be doped. In the same manner as the doping of P or B for imparting conductivity to the semiconductor film, the doping of the element of Group 0 can be performed by forming a plasma and accelerating with a porous electrode for doping. Since there is no legal regulation unlike P and B, the doping gas does not have to be diluted with hydrogen, and the throughput is high. For example, in the case of Ar, the concentration in the semiconductor film is 5 × 10 ¹⁸ ~ 1 × 10 ²¹ atoms / cm ³ , Preferably 1 × 10 ¹⁸ ~ 5 × 10 ²⁰ atoms / cm ³ Add to the extent. The acceleration voltage affects the concentration distribution of Ar in the thickness direction of the semiconductor film 502. Therefore, depending on whether the concentration is higher toward the surface of the film, the concentration is higher as the film is closer to the substrate, or whether the concentration of the entire film is uniform, Set as appropriate. In the present embodiment, the acceleration voltage is set to 30 kV.
[0035]
Note that laser light irradiation may be performed in an atmosphere of a gas in which hydrogen is added to a Group 0 element. In this case, the partial pressure of hydrogen is set to 1 to 3%.
[0036]
Next, as shown in FIG. 1B, the semiconductor film 502 is crystallized using the laser irradiation apparatus of the present invention. As the laser, a pulsed or continuous wave gas laser or solid-state laser can be used. Gas lasers include excimer lasers, Ar lasers, and Kr lasers, and solid-state lasers such as YAG lasers and YVO ₄ Laser, YLF laser, YAlO ₃ Laser, glass laser, ruby laser, alexandrite laser, Ti: sapphire laser, Y ₂ O ₃ Laser and the like. Examples of the solid-state laser include YAG, YVO doped with Cr, Nd, Er, Ho, Ce, Co, Ti, Yb or Tm. ₄ , YLF, YAlO ₃ A laser using a crystal such as is applied. The fundamental wave of the laser depends on the material to be doped, and a laser beam having a fundamental wave of about 1 μm can be obtained. Harmonics with respect to the fundamental wave can be obtained by using a nonlinear optical element.
[0037]
Furthermore, after converting an infrared laser beam emitted from a solid-state laser into a green laser beam by a nonlinear optical element, an ultraviolet laser beam obtained by another nonlinear optical element can be used.
[0038]
In this embodiment mode, a pulsed YAG laser is used. For example, when a YAG laser is used, the wavelength of the second harmonic that is easily absorbed by the semiconductor film is used. The oscillation frequency is 30 to 300 kHz and the energy density is 300 to 600 mJ / cm. ² (Typically 350-500 mJ / cm ² ), And the scanning speed may be set so that an arbitrary point can be irradiated several shots at a time.
[0039]
The laser light irradiation is performed in a load-lock type chamber in an atmosphere containing 99.99% or more, preferably 99.9999% or more of Group 0 gas. In this embodiment mode, Ar is used as a Group 0 gas.
[0040]
Note that the group 0 element to be doped and the group 0 element used for laser irradiation need not always be the same.
[0041]
By the above-described irradiation of the semiconductor film 502 with the laser light, a semiconductor film 503 with higher crystallinity is formed.
[0042]
Next, as shown in FIG. 1C, the semiconductor film 503 is patterned to form island-shaped semiconductor films 507 to 509, and various islands such as TFTs are formed using the island-shaped semiconductor films 507 to 509. A semiconductor device is formed.
[0043]
As described above, in the present invention, the semiconductor film is doped with Ar or the like in advance, and the laser light is irradiated in an atmosphere of Ar or the like to effectively prevent oxygen and nitrogen from entering the semiconductor film. Can be prevented. Therefore, variation in impurity concentration caused by fluctuation in energy density can be suppressed, and variation in mobility of the semiconductor film can be suppressed. In addition, in a TFT formed using the semiconductor film, variation in on-current as well as mobility can be suppressed.
[0044]
Further, as described in Patent Document 1, when a laser beam is irradiated in an atmosphere in which oxygen exists according to an empirical rule, the surface of a semiconductor film is roughened. However, by irradiating laser light in an atmosphere of Ar or the like, roughness of the semiconductor surface due to laser light irradiation can be suppressed, and variation in threshold value caused by variation in interface state density can be suppressed.
[0045]
When a TFT is manufactured as a semiconductor element, for example, a gate insulating film is formed so as to cover the island-shaped semiconductor films 507 to 509. For the gate insulating film, for example, silicon oxide, silicon nitride, silicon nitride oxide, or the like can be used. As a film formation method, a plasma CVD method, a sputtering method, or the like can be used.
[0046]
Next, a gate electrode is formed by forming a conductive film on the gate insulating film and patterning the conductive film. Then, an impurity for imparting n-type or p-type conductivity is added to the island-shaped semiconductor films 507 to 509 by using a gate electrode or a resist film formed and patterned as a mask, and the source region and the drain region are added. Then, an LDD region and the like are formed.
[0047]
Through the above series of steps, a TFT can be formed. Note that the method for manufacturing a semiconductor device of the present invention is not limited to the above-described manufacturing method of a TFT which is performed after forming an island-shaped semiconductor film. By using a semiconductor film crystallized by the laser irradiation method of the present invention as an active layer of a TFT, variations in mobility, threshold value, and on-current between elements can be suppressed.
[0048]
(Embodiment 2)
In the present embodiment, unlike Embodiment 1, an example in which a crystallization method using a catalytic element is combined with a crystallization method using a laser irradiation apparatus of the present invention will be described.
[0049]
First, the steps up to the step of forming the semiconductor film 502 and doping the semiconductor film 502 with a Group 0 element are performed with reference to FIG. Next, as shown in FIG. 2A, a nickel acetate solution containing 1 to 100 ppm by weight of Ni was applied to the surface of the semiconductor film 502 by a spin coating method. Note that the addition of the catalyst is not limited to the above method, and may be performed using a sputtering method, an evaporation method, a plasma treatment, or the like.
[0050]
Next, heat treatment was performed at 500 to 650 ° C. for 4 to 24 hours, for example, 570 ° C. for 14 hours. By this heat treatment, a semiconductor film 520 whose crystallization is promoted in the vertical direction toward the substrate 500 is formed from the surface to which the nickel acetate salt solution is applied (FIG. 2A).
[0051]
In this embodiment, nickel (Ni) is used as a catalyst element. However, germanium (Ge), iron (Fe), palladium (Pd), tin (Sn), lead (Pb), Elements such as cobalt (Co), platinum (Pt), copper (Cu), and gold (Au) may be used.
[0052]
Next, as shown in FIG. 2B, the semiconductor film 520 is crystallized using the laser irradiation apparatus of the present invention. In this embodiment mode, a pulsed excimer laser, a YAG laser, a YVO ₄ A laser or the like is used. For example, when a YAG laser is used, the wavelength of the second harmonic that is easily absorbed by the semiconductor film is used. The oscillation frequency is 30 to 300 kHz and the energy density is 300 to 600 mJ / cm. ² (Typically 350-500 mJ / cm ² ), And the scanning speed may be set so that an arbitrary point can be irradiated several shots at a time.
[0053]
The laser light irradiation is performed in a load-lock type chamber in an atmosphere containing 99.99% or more, preferably 99.9999% or more of Group 0 gas. In this embodiment mode, Ar is used as a Group 0 gas.
[0054]
Note that the group 0 element to be doped and the group 0 element used for laser irradiation need not always be the same.
[0055]
By the above-described irradiation of the semiconductor film 520 with the laser light, the semiconductor film 521 having higher crystallinity is formed.
[0056]
Note that the catalyst element (here, Ni) is approximately 1 × 10 5 in the semiconductor film 521 crystallized using the catalyst element as illustrated in FIG. ¹⁹ atoms / cm ³ It is thought that it is contained in the concentration of about. Next, gettering of a catalyst element existing in the semiconductor film 521 is performed.
[0057]
First, an oxide film 522 is formed over the surface of the semiconductor film 521 as shown in FIG. By forming the oxide film 522 having a thickness of about 1 to 10 nm, the surface of the semiconductor film 521 can be prevented from being roughened by etching in a later etching step.
[0058]
The oxide film 522 can be formed using a known method. For example, the surface of the semiconductor film 521 may be formed by oxidizing the surface of the semiconductor film 521 with an aqueous solution in which sulfuric acid, hydrochloric acid, nitric acid, and the like are mixed with hydrogen peroxide, ozone water, or plasma treatment in an atmosphere containing oxygen. Alternatively, it may be formed by heat treatment, ultraviolet irradiation, or the like. Further, an oxide film may be separately formed by a plasma CVD method, a sputtering method, an evaporation method, or the like.
[0059]
Next, on the oxide film 522, a rare gas element is ²⁰ atoms / cm ³ A gettering semiconductor film 523 containing the above concentration is formed with a thickness of 25 to 250 nm by a sputtering method. The gettering semiconductor film 523 preferably has a lower film density than the semiconductor film 521 in order to increase the etching selectivity with respect to the semiconductor film 521.
[0060]
As the rare gas element, one or more kinds selected from helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe) are used.
[0061]
Next, heat treatment is performed by using a furnace annealing method or an RTA method to perform gettering. In the case of performing the furnace annealing method, heat treatment is performed at 450 to 600 ° C. in a nitrogen atmosphere for 0.5 to 12 hours. When the RTA method is used, a lamp light source for heating is turned on for 1 to 60 seconds, preferably 30 to 60 seconds, and this is repeated 1 to 10 times, preferably 2 to 6 times. Although the light emission intensity of the lamp light source is arbitrary, the semiconductor film is instantaneously heated to about 600 to 1000 ° C., preferably about 700 to 750 ° C.
[0062]
By the heat treatment, the catalytic element in the semiconductor film 521 moves to the gettering semiconductor film 523 by diffusion as shown by an arrow, and is gettered.
[0063]
Next, the semiconductor film 523 for gettering is selectively etched and removed. Etching is ClF ₃ Etching without using plasma by hydrazine or tetraethylammonium hydroxide (chemical formula (CH ₃ ) ₄ It can be performed by wet etching using an alkaline solution such as an aqueous solution containing NOH). At this time, the semiconductor film 521 can be prevented from being etched by the oxide film 522.
[0064]
Next, the oxide film 522 is removed with hydrofluoric acid.
[0065]
Next, the semiconductor film 521 after removing the oxide film 522 is patterned to form island-shaped semiconductor films 524 to 526 (FIG. 2D).
[0066]
Note that the gettering step in the present invention is not limited to the method described in this embodiment. The catalyst element in the semiconductor film may be reduced by using another method.
[0067]
Next, various semiconductor elements typified by TFTs are formed using the island-shaped semiconductor films 524 to 526.
[0068]
Note that by performing crystallization by irradiation with a laser beam after crystallization using a catalytic element as in this embodiment, the crystallinity of the semiconductor film can be further improved as compared with the case of Embodiment 1. In Embodiment 1, crystal nuclei are randomly generated after laser light irradiation, and crystallization proceeds. On the other hand, in the case of the present embodiment, the crystal formed during crystallization by the catalytic element remains without being melted by laser light irradiation on the side closer to the substrate, and crystallization proceeds using the crystal as a crystal nucleus. Therefore, crystallization by laser light irradiation easily proceeds uniformly from the substrate side to the surface, and the surface roughness is suppressed as compared with the case of the first embodiment. Therefore, variation in characteristics of a semiconductor element to be formed later, typically, a TFT is further suppressed.
[0069]
Note that, in this embodiment mode, a structure in which heat treatment is performed after the addition of a catalytic element to promote crystallization, and then the crystallinity is further improved by laser light irradiation is described. The present invention is not limited to this, and the step of the heat treatment may be omitted. Specifically, the crystallinity may be increased by adding a catalyst element and then irradiating with laser light instead of heat treatment.
[0070]
In this embodiment mode, the semiconductor film is doped with a rare gas and then crystallized with a catalytic element. However, the present invention is not limited to this. The doping of the semiconductor film with a rare gas may be performed before crystallization by laser light. Therefore, the semiconductor film may be doped with a rare gas after crystallization by the catalytic element.
[0071]
(Embodiment 3)
In the present embodiment, unlike Embodiment 2, an example in which a crystallization method using a catalytic element is combined with a crystallization method using a laser irradiation apparatus of the present invention will be described.
[0072]
First, the steps up to the step of forming the semiconductor film 502 and doping the semiconductor film 502 with a Group 0 element are performed with reference to FIG. Next, a mask 540 having an opening is formed over the semiconductor film 502. Then, as shown in FIG. 3A, a nickel acetate solution containing 1 to 100 ppm by weight of Ni was applied to the surface of the semiconductor film 502 by a spin coating method. Note that the addition of the catalyst is not limited to the above method, and may be performed using a sputtering method, an evaporation method, a plasma treatment, or the like. The applied nickel acetate solution comes into contact with the semiconductor film 502 at the opening of the mask 540 (FIG. 3A).
[0073]
Next, heat treatment was performed at 500 to 650 ° C. for 4 to 24 hours, for example, 570 ° C. for 14 hours. By this heat treatment, a semiconductor film 530 whose crystallization is promoted is formed from the surface to which the nickel acetate salt solution has been applied, as shown by a solid line arrow (FIG. 3A).
[0074]
Note that the catalyst elements listed in Embodiment Mode 2 can be used.
[0075]
Next, after removing the mask 540, as shown in FIG. 3B, the semiconductor film 530 is crystallized using the laser irradiation apparatus of the present invention. In this embodiment mode, a pulsed excimer laser, a YAG laser, a YVO ₄ A laser or the like is used. For example, when a YAG laser is used, the wavelength of the second harmonic that is easily absorbed by the semiconductor film is used. The oscillation frequency is 30 to 300 kHz and the energy density is 300 to 600 mJ / cm. ² (Typically 350-500 mJ / cm ² ), And the scanning speed may be set so that an arbitrary point can be irradiated several shots at a time.
[0076]
The laser light irradiation is performed in a load-lock type chamber in an atmosphere containing 99.99% or more, preferably 99.9999% or more of Group 0 gas. In this embodiment mode, Ar is used as a Group 0 gas.
[0077]
Note that the group 0 element to be doped and the group 0 element used for laser irradiation need not always be the same.
[0078]
By the above-described irradiation of the semiconductor film 531 with the laser light, the semiconductor film 531 with higher crystallinity is formed.
[0079]
Note that the catalyst element (here, Ni) is approximately 1 × 10 5 in the semiconductor film 531 crystallized using the catalyst element as shown in FIG. ¹⁹ atoms / cm ³ It is thought that it is contained in the concentration of about. Next, gettering of a catalyst element existing in the semiconductor film 531 is performed.
[0080]
First, as shown in FIG. 3C, a silicon oxide film 532 for a mask is formed with a thickness of 150 nm so as to cover the semiconductor film 531, an opening is provided by patterning, and a part of the semiconductor film 531 is exposed. Let it. Then, a region 533 to which phosphorus is added is provided in the semiconductor film 531 by adding phosphorus.
[0081]
In this state, when heat treatment is performed in a nitrogen atmosphere at 550 to 800 ° C. for 5 to 24 hours, for example, at 600 ° C. for 12 hours, the region 533 to which phosphorus is added to the semiconductor film 531 functions as a gettering site, The catalyst element remaining in 531 segregates in the gettering region 533 to which phosphorus has been added (FIG. 3C).
[0082]
Then, by removing the region 533 to which phosphorus is added by etching, the concentration of the catalyst element is reduced to 1 × 10 5 in the remaining region of the semiconductor film 531. ¹⁷ atms / cm ³ It can be reduced to the following.
[0083]
Then, after removing the silicon oxide film 532 for a mask, the semiconductor film 531 is patterned to form island-shaped semiconductor films 534 to 536 (FIG. 3D).
[0084]
Note that the gettering step in the present invention is not limited to the method described in this embodiment. The catalyst element in the semiconductor film may be reduced by using another method.
[0085]
Next, as shown in FIG. 3D, the semiconductor film 503 is patterned to form island-shaped semiconductor films 534 to 536, and various semiconductors typified by TFTs are formed using the island-shaped semiconductor films 534 to 536. An element is formed.
[0086]
By performing crystallization by irradiation with laser light after crystallization with a catalytic element as in this embodiment, the crystallinity of the semiconductor film can be further improved as compared with the case of Embodiment 1. In Embodiment 1, crystal nuclei are randomly generated after laser light irradiation, and crystallization proceeds. On the other hand, in the case of the present embodiment, the crystal formed during crystallization by the catalytic element remains without being melted by laser light irradiation on the side closer to the substrate, and crystallization proceeds using the crystal as a crystal nucleus. Therefore, crystallization by laser light irradiation easily proceeds uniformly from the substrate side to the surface, and the surface roughness is suppressed as compared with the case of the first embodiment. Therefore, variation in characteristics of a semiconductor element to be formed later, typically, a TFT is further suppressed.
[0087]
Note that, in this embodiment mode, a structure in which heat treatment is performed after the addition of a catalytic element to promote crystallization, and then the crystallinity is further improved by laser light irradiation is described. The present invention is not limited to this, and the step of the heat treatment may be omitted. Specifically, the crystallinity may be increased by adding a catalyst element and then irradiating with laser light instead of heat treatment.
[0088]
In this embodiment mode, the semiconductor film is doped with a rare gas and then crystallized with a catalytic element. However, the present invention is not limited to this. The doping of the semiconductor film with a rare gas may be performed before crystallization by laser light. Therefore, the semiconductor film may be doped with a rare gas after crystallization by the catalytic element.
[0089]
(Embodiment 4)
In this embodiment mode, a structure of a laser irradiation apparatus having a load lock type chamber will be described.
[0090]
FIG. 4 shows the configuration of the laser irradiation apparatus of the present embodiment. The laser irradiation chamber 1206 is surrounded by a partition 1230. Note that since laser light has high directivity and high energy density, the partition wall 1230 preferably has a property of absorbing reflected light in order to prevent the reflected light from irradiating an inappropriate portion. Note that cooling water may be circulated in the partition to prevent the temperature of the partition from rising due to absorption of reflected light.
[0091]
Further, as shown in FIG. 4, a means for heating the partition wall (partition heating means) 1240 may be provided so that the partition wall is heated when the inside of the laser irradiation chamber is evacuated.
[0092]
The gate 1210 corresponds to a transfer port of the substrate to the laser irradiation chamber 1206. Further, the gas in the laser irradiation chamber 1206 can be exhausted from the laser irradiation chamber 1206 by an exhaust system 1231 connected to the exhaust port 1211.
Further, a rare gas can be supplied into the laser irradiation chamber 1206 by a rare gas supply system 1250 connected to the supply port 1251.
[0093]
Reference numeral 1212 denotes a stage on which the substrate 1203 is placed. By moving the position of the stage by the position control means 1242, the position of the substrate can be controlled and the irradiation position of the laser beam can be moved. As shown in FIG. 4, a means (substrate heating means) 1241 for heating the substrate may be provided on the stage 1212.
[0094]
The opening 1232 provided in the partition wall 1230 is covered with a window (transmission window) 1233 that transmits laser light. Note that the transmission window 1233 is desirably made of a material that does not easily absorb laser light, for example, quartz or the like is suitable. A gasket 1236 is provided between the transmission window 1233 and the partition wall 1230, so that air can be prevented from entering the laser irradiation chamber from a gap between the transmission window 1233 and the partition wall 1230.
[0095]
First, the substrate 1203 over which the semiconductor film is formed is transported, and after closing the gate 1210, the inside of the laser irradiation chamber 1206 is kept in a rare gas atmosphere using the exhaust system 1231 and the rare gas supply system 1250.
[0096]
The laser light oscillated from the laser oscillation device 1213 is shaped into a beam spot by the optical system 1214, and is irradiated on the substrate 1203. The incident angle θ is preferably larger than 0 °, more preferably about 5 ° to 30 °, in order to prevent return light and to perform uniform irradiation.
[0097]
Note that the laser irradiation chamber 1206 illustrated in FIG. 4 may be one of the chambers included in the multi-chamber. A chamber for doping a rare gas element into a semiconductor film is provided, and a series of steps from doping of a rare gas element to crystallization of laser light are performed in a multi-chamber without exposure to the atmosphere, so that impurities can be removed from the semiconductor film. Can be prevented more effectively.
[0098]
Note that by using the above laser irradiation apparatus for crystallization of a semiconductor film, crystallinity of the semiconductor film can be made more uniform. The method for manufacturing a semiconductor device of the present invention can be used for a method for manufacturing an integrated circuit or a semiconductor display device. In particular, a liquid crystal display device, a light emitting device having a light emitting element typified by an organic light emitting element in each pixel, a semiconductor display device such as a DMD (Digital Micromirror Device), a PDP (Plasma Display Panel), and a FED (Field Emission Display). When used for a semiconductor element such as a transistor provided in a pixel portion, horizontal stripes due to energy distribution of laser light applied to the pixel portion can be suppressed from being visually recognized.
[0099]
(Embodiment 5)
FIG. 5 shows the configuration of the laser irradiation apparatus of the present embodiment. The laser light oscillated from the laser oscillation device 1500 is changed to linearly polarized light by the polarizer 1507 and enters the beam expander 1508. On the other hand, the laser beam oscillated from the laser oscillation device 1501 is changed into linearly polarized light by the polarizer 1504, and then the polarization angle is changed by 90 degrees in the polarizing plate 1506. Then, the light enters the beam expander 1508 together with the laser light oscillated from the laser oscillation device 1500 by the polarizer 1507.
[0100]
Note that in this embodiment, a shutter 1502 that blocks laser light is provided between the laser oscillation device 1500 and the polarizer 1507, but is not necessarily provided. Further, a shutter 1503 for blocking laser light is provided between the laser oscillation device 1501 and the polarizer 1504, but is not necessarily provided.
[0101]
Then, the spread of the incident laser light can be suppressed and the size of the beam spot can be adjusted by the beam expander 1508.
[0102]
The laser light emitted from the beam expander 1508 is condensed by the cylindrical lens 1509 so that the beam spot has a rectangular, elliptical, or linear shape. Then, the collected laser light is reflected by the mirror 1510 and enters the lens 1511. The incident laser light is condensed again by the lens 1511 and is irradiated on the substrate 1514 in the laser irradiation chamber 1513. In this embodiment mode, Fθ telecentric is used as the lens 1511.
[0103]
In this embodiment mode, polarizers 1504 and 1507, a beam expander 1508, a polarizing plate 1506, shutters 1502 and 1503, a cylindrical lens 1509, a mirror 1510, and a lens 1511 are included in the optical system.
[0104]
In the laser irradiation chamber 1513, a substrate 1514 is mounted on a stage 1515, and the position of the stage 1515 is controlled by three position control means 1516 to 1518. Specifically, the stage 1515 can be rotated in a horizontal plane by the φ-direction position control means 1516. Further, the stage 1515 can be moved in the X direction within the horizontal plane by the X direction position control means 1517. In addition, the stage 1515 can be moved in the Y direction within the horizontal plane by the Y direction position control means 1518. The operation of each position control means is controlled by the central processing unit 1519.
[0105]
As in this embodiment, a monitor 1512 using a light receiving element such as a CCD may be provided so that the position of the substrate can be accurately grasped.
[0106]
Note that, when one of a plane including a short side and a plane including a long side is defined as an incident plane, which is a plane perpendicular to the irradiation surface and the shape of the beam spot is considered to be a rectangle, The incident angle θ is such that the length of the short side or the long side included in the incident surface is W, and the thickness of the substrate which is provided on the irradiation surface and has a light transmitting property with respect to the laser light is d. At some point, it is desirable to satisfy θ ≧ arctan (W / 2d). When the locus of the laser beam is not on the incident surface, the incident angle of the locus projected on the incident surface is defined as θ. When the laser light is incident at this incident angle θ, the reflected light from the front surface of the substrate and the reflected light from the back surface of the substrate do not interfere with each other, and uniform laser light irradiation can be performed. The above discussion has assumed that the refractive index of the substrate is 1. Actually, in many cases, the refractive index of the substrate is around 1.5, and if this numerical value is taken into account, a calculated value larger than the angle calculated in the above discussion can be obtained. However, since the energy at both ends in the longitudinal direction of the beam spot is attenuated, the influence of interference at this portion is small, and the above-described calculated value can sufficiently obtain the effect of interference attenuation.
[0107]
Note that the optical system in the laser irradiation apparatus of the present invention is not limited to the structure described in this embodiment.
[0108]
(Embodiment 6)
In this embodiment, a structure of a laser irradiation apparatus that can apply ultrasonic vibration to a semiconductor film when laser light irradiation is performed will be described.
[0109]
FIG. 6A shows a cross-sectional view of the laser irradiation apparatus of this embodiment. The laser irradiation chamber 601 is surrounded by a partition 602. Note that since the laser light has high directivity and high energy density, the partition wall 602 preferably has a property of absorbing the reflected light in order to prevent the reflected light from irradiating an inappropriate portion. Note that cooling water may be circulated in the partition to prevent the temperature of the partition from rising due to absorption of reflected light. Further, a means for heating the partition wall (partition heating means) may be provided so that the partition wall is heated when the inside of the laser irradiation chamber is evacuated.
[0110]
Further, the gas in the laser irradiation chamber 601 can be exhausted from the laser irradiation chamber 601 by an exhaust system 604 connected to an exhaust port 603. Further, a rare gas can be supplied into the laser irradiation chamber 601 by a rare gas supply system 606 connected to the supply port 605.
[0111]
Reference numeral 607 denotes a stage capable of ejecting a Group 0 gas from a hole provided on the surface thereof, as shown in FIG. The gas ejected from the stage 607 can keep the substrate 608 on which the semiconductor film is formed horizontal like a hovercraft.
[0112]
Reference numeral 609 corresponds to fixing means for fixing one end of the substrate 608, and reference numeral 610 corresponds to a conveyor capable of scanning the substrate 608 by controlling the position of the fixing means. The conveyor 610 is fixed to the stage 607. Then, as shown in FIG. 6B, by making the moving direction of the fixing means by the conveyor 610 perpendicular to the moving direction of the stage 607, the entire surface of the substrate 608 can be irradiated with laser light.
[0113]
The partition 602 is provided with a window (transmission window) 612 through which laser light is transmitted. Note that the transmission window 612 is preferably made of a material that does not easily absorb laser light, and for example, quartz is suitable.
[0114]
The laser irradiation apparatus described in this embodiment mode applies vibration to the substrate 608 by ultrasonic waves in the horizontal direction using the ultrasonic transducer 611. Specifically, by applying vibration to the stage 607, the conveyor 610, or the fixing means 609 by ultrasonic waves in the horizontal direction by the ultrasonic vibrator 611, vibration can be indirectly applied to the substrate 608.
[0115]
As the ultrasonic vibrator 611, for example, a piezoelectric vibrator made of quartz or the like, an electrostrictive vibrator (such as BaTiO), a magnetostrictive vibrator (such as nickel or ferrite), or another vibrator can be used.
[0116]
The frequency of the vibration applied to the substrate 608 is desirably 100 kHz or more and less than 30 MHz. By applying vibration by ultrasonic waves, impurities such as oxygen and nitrogen melted in the semiconductor film at the time of laser light irradiation can be prevented from segregating at crystal grain boundaries when the semiconductor film is solidified. In addition, the surface of the semiconductor film can be made flatter.
[0117]
【Example】
Hereinafter, examples of the present invention will be described.
[0118]
A structure of a pixel of a light-emitting device, which is one of semiconductor devices formed using the laser irradiation device of the present invention, will be described with reference to FIGS.
[0119]
In FIG. 7, a base film 6001 is formed over a substrate 6000, and a plurality of transistors 6002 are formed over the base film 6001. The transistor 6002 includes an active layer 6003, a gate electrode 6005, and a gate insulating film 6004 sandwiched between the active layer 6003 and the gate electrode 6005.
[0120]
As the active layer 6003, a polycrystalline semiconductor film crystallized by using the laser irradiation apparatus of the present invention is used. The active layer may use silicon germanium instead of silicon. When silicon germanium is used, the concentration of germanium is preferably about 0.01 to 4.5 atomic%. Further, silicon to which carbon nitride is added may be used.
[0121]
For the gate insulating film 6004, silicon oxide, silicon nitride, or silicon oxynitride can be used. Further, a film obtained by laminating them, for example, SiO 2 ₂ A film in which SiN is stacked thereon may be used as a gate insulating film. In addition, SiO ₂ Is manufactured by using TEOS (Tetraethyl Orthosilicate) and O ₂ At a reaction pressure of 40 Pa, a substrate temperature of 300 to 400 ° C., a high frequency (13.56 MHz), and a power density of 0.5 to 0.8 W / cm. ² To form a silicon oxide film. The silicon oxide film thus manufactured can obtain good characteristics as a gate insulating film by subsequent thermal annealing at 400 to 500 ° C. Aluminum nitride can be used as the gate insulating film. Aluminum nitride has a relatively high thermal conductivity and can effectively diffuse heat generated in the TFT. Alternatively, a layer obtained by stacking aluminum nitride after forming silicon oxide or silicon oxynitride containing no aluminum may be used as the gate insulating film. In addition, SiO formed by RF sputtering using Si as a target is used. ₂ May be used as a gate insulating film.
[0122]
The gate electrode 6005 is formed using an element selected from Ta, W, Ti, Mo, Al, and Cu, or an alloy material or a compound material containing the above element as a main component. Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus may be used. Instead of a single-layer conductive film, a stacked conductive film including a plurality of layers may be used.
[0123]
For example, the first conductive film is formed of tantalum nitride (TaN), the second conductive film is formed of W, the first conductive film is formed of tantalum nitride (TaN), and the second conductive film is formed of Ti. The first conductive film is formed of tantalum nitride (TaN), the second conductive film is formed of Al, the first conductive film is formed of tantalum nitride (TaN), and the second conductive film is formed of tantalum nitride (TaN). Is preferably formed using a combination of Cu and Cu.
Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus, or an AgPdCu alloy may be used as the first conductive film and the second conductive film.
[0124]
Further, the present invention is not limited to the two-layer structure, and may have a three-layer structure in which a tungsten film, an alloy of aluminum and silicon (Al—Si) film, and a titanium nitride film are sequentially stacked. When a three-layer structure is used, tungsten nitride may be used instead of tungsten, or an aluminum-titanium alloy film (Al-Ti) may be used instead of an aluminum-silicon alloy (Al-Si) film. Alternatively, a titanium film may be used instead of the titanium nitride film. Note that it is important to appropriately select an optimal etching method and an etchant type depending on the material of the conductive film.
[0125]
The transistor 6002 is covered with a first interlayer insulating film 6006, and a second interlayer insulating film 6007 and a third interlayer insulating film 6008 are stacked over the first interlayer insulating film 6006. . As the first interlayer insulating film 6006, a single layer or a stacked layer of a silicon oxide, a silicon nitride, or a silicon oxynitride film can be used by a plasma CVD method or a sputtering method. Alternatively, a film in which a silicon oxynitride film having a higher molar ratio of oxygen than nitrogen is stacked over a silicon oxynitride film having a higher molar ratio of nitrogen than oxygen may be used as the first interlayer insulating film 6006. Note that when heat treatment (heat treatment at 300 to 550 ° C. for 1 to 12 hours) is performed after the first interlayer insulating film 6006 is formed, hydrogen contained in the first interlayer insulating film 6006 is used to form the active layer 6003. Can terminate (hydrogenate) the dangling bonds of the semiconductor contained in the semiconductor.
[0126]
For the second interlayer insulating film 6007, non-photosensitive acrylic can be used. As the third interlayer insulating film 6008, a film which does not easily transmit a substance which causes deterioration of a light-emitting element, such as moisture or oxygen, to be transmitted as compared to other insulating films. Typically, for example, it is desirable to use a DLC film, a carbon nitride film, a silicon nitride film formed by an RF sputtering method, or the like.
[0127]
In FIG. 7, reference numeral 6010 denotes an anode; 6011, an electroluminescent layer; and 6012, a cathode. A portion where the anode 6010, the electroluminescent layer 6011, and the cathode 6012 overlap corresponds to the light emitting element 6013. The transistor 6002 is a driving transistor that controls a current supplied to the light-emitting element 6013, and is connected to the light-emitting element 6013 directly or in series through another circuit element.
[0128]
The electroluminescent layer 6011 has a structure in which a light-emitting layer alone or a plurality of layers including a light-emitting layer is stacked.
[0129]
The anode 6010 is formed over the third interlayer insulating film 6008. An organic resin film 6014 used as a partition is formed over the third interlayer insulating film 6008. The organic resin film 6014 has an opening 6015, and a light emitting element 6013 is formed by overlapping the anode 6010, the electroluminescent layer 6011, and the cathode 6012 in the opening.
[0130]
Then, a protective film 6016 is formed over the organic resin film 6014 and the cathode 6012. As in the case of the third interlayer insulating film 6008, a film which is less likely to transmit a substance such as moisture or oxygen which causes deterioration of the light-emitting element than the other insulating films is used for the protective film 6016. Typically, for example, it is desirable to use a DLC film, a carbon nitride film, a silicon nitride film formed by an RF sputtering method, or the like. Alternatively, a film in which a substance such as moisture or oxygen is not easily transmitted and a film in which a substance such as moisture or oxygen is easily transmitted can be stacked and used as a protective film.
[0131]
In addition, the organic resin film 6014 is heated in a vacuum atmosphere to remove adsorbed moisture, oxygen, and the like before the electroluminescent layer 6011 is formed. Specifically, heat treatment is performed at 100 ° C. to 200 ° C. for about 0.5 to 1 hour in a vacuum atmosphere. Preferably 3 × 10 ^-7 Torr or less, 3 × 10 if possible ^-8 Most preferably, it is equal to or less than Torr. When the electroluminescent layer is formed after the organic resin film is subjected to the heat treatment in a vacuum atmosphere, the reliability can be further improved by maintaining the organic resin film in the vacuum atmosphere until immediately before the film formation.
[0132]
The edge of the opening 6015 of the organic resin film 6014 may be rounded so that the electroluminescent layer 6011 formed so as to partially overlap the organic resin film 6014 has no hole at the end. Is desirable. Specifically, it is desirable that the radius of curvature of the curve drawn by the cross section of the organic resin film in the opening is about 0.2 to 2 μm.
[0133]
With the above structure, coverage of an electroluminescent layer and a cathode formed later can be improved, and a short circuit between the anode 6010 and the cathode 6012 in a hole formed in the electroluminescent layer 6011 can be prevented. In addition, by relaxing the stress of the electroluminescent layer 6011, a defect called a shrink in which a light emitting region is reduced can be reduced, and reliability can be improved.
[0134]
Note that FIG. 7 illustrates an example in which a positive photosensitive acrylic resin is used for the organic resin film 6014. The photosensitive organic resin includes a positive type in which a portion exposed to energy rays such as light, electrons, and ions is removed, and a negative type in which the exposed portion remains. In the present invention, a negative type organic resin film may be used. Alternatively, the organic resin film 6014 may be formed using photosensitive polyimide. In the case where the organic resin film 6014 is formed using negative acrylic, the end of the opening 6015 has an S-shaped cross section. At this time, the radius of curvature at the upper end and the lower end of the opening is desirably 0.2 to 2 μm.
[0135]
The anode 6010 can be formed using a transparent conductive film. In addition to ITO, a transparent conductive film in which 2 to 20% of zinc oxide (ZnO) is mixed with indium oxide may be used. In FIG. 7, ITO is used as the anode 6010. The anode 6010 may be polished by a CMP method or by wiping with a polyvinyl alcohol-based porous body so that its surface is planarized. After polishing using a CMP method, the surface of the anode 6010 may be subjected to ultraviolet irradiation, oxygen plasma treatment, or the like.
[0136]
For the cathode 6012, a known material can be used as long as it is a conductive film having a small work function. For example, Ca, Al, CaF, MgAg, AlLi and the like are desirable.
[0137]
Note that FIG. 7 illustrates a structure in which light emitted from the light-emitting element is applied to the substrate 6000. However, a light-emitting element having a structure in which light is directed to the opposite side to the substrate may be used.
[0138]
Further, in FIG. 7, one of the transistors 6002 is electrically connected to the anode 6010 of the light-emitting element; however, the present invention is not limited to this structure, and one of the transistors 6002 may be connected to the cathode 6001 of the light-emitting element. good. In this case, the cathode is formed over the third interlayer insulating film 6008. And it is formed using TiN or the like.
[0139]
Actually, when completed up to FIG. 7, packaging is performed with a protective film (laminate film, ultraviolet curable resin film, etc.) with high airtightness and less degassing so as not to be further exposed to the outside air, or a light-transmitting cover material ( Encapsulation) is preferable. At this time, the reliability of the OLED is improved by setting the inside of the cover material to an inert atmosphere or arranging a hygroscopic material (for example, barium oxide) inside.
[0140]
Note that the light-emitting device of the present invention is not limited to the manufacturing method described above. Further, the semiconductor device of the present invention is not limited to a light emitting device.
[0141]
【The invention's effect】
In the present invention, by doping Ar or the like in advance in a semiconductor film and irradiating a laser beam in an atmosphere of Ar or the like, oxygen and nitrogen can be effectively prevented from entering the semiconductor film. . Therefore, variation in impurity concentration caused by fluctuation in energy density can be suppressed, and variation in mobility of the semiconductor film can be suppressed. In addition, in a TFT formed using the semiconductor film, variation in on-current as well as mobility can be suppressed.
[0142]
Further, as described in Patent Document 1, when a laser beam is irradiated in an atmosphere in which oxygen exists according to an empirical rule, the surface of a semiconductor film is roughened. However, by irradiating laser light in an atmosphere of Ar or the like, roughness of the semiconductor surface due to laser light irradiation can be suppressed, and variation in threshold value caused by variation in interface state density can be suppressed.
[Brief description of the drawings]
FIG. 1 illustrates a method for manufacturing a semiconductor device.
FIG. 2 illustrates a method for manufacturing a semiconductor device.
FIG. 3 illustrates a method for manufacturing a semiconductor device.
FIG. 4 is a diagram illustrating a configuration of a laser irradiation apparatus having a load-lock type chamber.
FIG. 5 is a diagram illustrating a configuration of a laser irradiation apparatus.
FIG. 6 is a diagram illustrating a configuration of a laser irradiation apparatus.
FIG. 7 is a cross-sectional view of a light emitting device manufactured using the laser irradiation device of the present invention.
FIG. 8 is a diagram showing a mechanism of mixing of impurities into a semiconductor film.

Claims (11)

A method for manufacturing a semiconductor device, wherein a rare gas is added to a semiconductor film formed over an insulating surface by an ion doping method, and the semiconductor film to which the rare gas is added is irradiated with laser light. In claim 1,
The method for manufacturing a semiconductor device, wherein the rare gas is Ar. In claim 2,
The method for manufacturing a semiconductor device, wherein a concentration of the first rare gas is 5 × 10 ¹⁸ to 1 × 10 ²¹ atoms / cm ³ . A first rare gas is added to the semiconductor film formed over the insulating surface using an ion doping method,
In a method for manufacturing a semiconductor device, a semiconductor film to which the first rare gas is added is irradiated with laser light in an atmosphere of a second rare gas. A first rare gas is added to the semiconductor film formed over the insulating surface using an ion doping method,
A method for manufacturing a semiconductor device in which a semiconductor film to which the first rare gas is added is irradiated with laser light in an atmosphere of a second rare gas,
A method for manufacturing a semiconductor device, comprising: applying ultrasonic vibration to a semiconductor film to which the first rare gas is added during irradiation with the laser light. In claim 5,
The method of manufacturing a semiconductor device, wherein a frequency of the vibration by the ultrasonic waves is greater than or equal to 100 kHz and less than 30 MHz. In any one of claims 4 to 6,
The method for manufacturing a semiconductor device, wherein the first or second rare gas is Ar. In any one of claims 4 to 7,
The method for manufacturing a semiconductor device, wherein a concentration of the first rare gas is 5 × 10 ¹⁸ to 1 × 10 ²¹ atoms / cm ³ . In any one of claims 1 to 8,
The method for manufacturing a semiconductor device, wherein the laser light is output by pulse oscillation. In any one of claims 1 to 8,
The method for manufacturing a semiconductor device, wherein the laser light is output by continuous oscillation. A semiconductor device formed by using the manufacturing method according to claim 1.

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