JP2002158173A - Method for manufacturing thin film, semiconductor thin film, semiconductor device, method for manufacturing semiconductor thin film, and system for manufacturing semiconductor thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a thin film, especially a semiconductor thin film, in which volatile gases, e.g. hydrogen, in a thin film can be reduced just like a case employing an electric furnace without sacrifice of productivity while preventing breakage of the film. SOLUTION: A thin film containing volatile gas is irradiated with excimer laser light 5 having pulse width of 60 nS or longer thus degassing the thin film. The thin film can be protected against breakage even if it is recrystallized subsequently and short time processing is realized by excimer laser irradiation. Alternatively, a thin film containing 2 atm.% or more of volatile gas is irradiated with excimer laser having pulse width of 60 nS or longer thus degassing the thin film while crystallizing. Since nuclei are formed uniformly, size of crystal particles is made uniform and variations of characteristics are suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thin film of polycrystalline silicon or amorphous silicon on a substrate such as a conductor, an insulating film, or an insulating substrate in order to manufacture a semiconductor device on the substrate. More particularly, the present invention relates to a method for producing a thin film using laser irradiation.

[0002]

2. Description of the Related Art Thin film semiconductor devices are expected to be applied to drive substrates such as active matrix type liquid crystal displays for display as an example, and their development is being actively promoted. Polycrystalline silicon, amorphous silicon, or a film in which both are stacked and mixed are used for the active layer of the thin film transistor. In particular, polycrystalline silicon thin film transistors can realize small, high-definition active matrix color liquid crystal displays.
Its attention is high. In order to form a thin film transistor as a pixel switching element on an insulating substrate made of a material such as transparent glass, a polycrystalline silicon thin film which is merely an electrode material or a resistance material in the conventional semiconductor technology is formed by using an active layer (channel region) of the transistor. ) Must be improved so that the required mobility can be obtained. If such a high mobility is obtained, it is possible to form a pixel driving circuit on this substrate at the same time as the pixel transistor. By using a thin film transistor having high mobility, the number of manufacturing steps and cost of a display can be significantly reduced, and at the same time, reliability can be improved.

On the other hand, as a device processing technique for such a thin film transistor, a high-temperature process employing a processing temperature of 900 ° C. or higher has been established. This high-temperature process is a method in which a semiconductor thin film is formed on a substrate having high heat resistance such as quartz, and is subjected to solid phase growth over a long period of time for reforming, whereby large crystal grains of polycrystalline silicon grow. According to this method, a high carrier mobility of about 100 cm ² / V · s can be obtained, but since the quartz substrate is expensive, the manufacturing cost is increased.

Therefore, instead of the so-called high-temperature process using a quartz substrate, a low-temperature polycrystalline process that can be formed at a processing temperature of about 600 ° C. or less, which is lower than the heat-resistant temperature of glass, using a glass substrate as a thermal process has been eagerly developed. Have been. As a method of making the manufacturing process of a thin film semiconductor device a low temperature process, a laser annealing technique using an energy beam, particularly a laser beam, has attracted attention.
The methods shown in (a) to (e) of FIG. 5 are used.

As shown in FIG. 15A, an amorphous semiconductor thin film 102 such as amorphous silicon is grown on a low heat resistant insulating substrate 101 such as glass. When, for example, a PECVD (plasma enhanced CVD) apparatus is used to form the amorphous semiconductor thin film 102, the film contains about 2 to 20 at% of hydrogen. Then, as shown in FIG. 15 (b), the substrate is put into an electric furnace,
Degas for about an hour. By this degassing process,
The hydrogen concentration in the film is less than 2 at%. Thereafter, as shown in FIG. 15C, the laser light 105 is locally irradiated, the irradiated area 104 is melted, and the laser light 10 is irradiated.
By stopping the step 5, the temperature of the irradiation area 104 is reduced to become a recrystallization area 106 as shown in FIG. By repeating such local irradiation of the laser beam 105, a recrystallized region 106 spreads over the substrate 101 and a polycrystalline silicon film having large crystal grains is obtained as shown in FIG. Can be. This ELA (Excimer Laser Niel) method can be applied to conductors, insulating films and the like in addition to semiconductors such as Si and Ge.

[0006]

However, in the process of forming the polycrystalline silicon film, if the first amorphous semiconductor thin film 102 is formed by plasma CVD, hydrogen in the film is degassed. Is subjected to an annealing treatment in an electric furnace, but it is necessary to carry out degassing annealing at, for example, 420 ° C. for a long time for about 2 hours, which hinders an improvement in productivity. Problems such as deformation of the substrate due to heat for the gas treatment and diffusion of contaminants from the glass into the thin film occur.

As one of the methods for solving such a problem, there is a method using an excimer laser tool, for example, Japanese Patent Application Laid-Open Nos. 9-186336 and 9-28.
As described in Japanese Patent No. 3443, this type of excimer laser has a low energy of, for example, 60 to 150 m.
An example is known in which laser irradiation is performed at J / cm ² to achieve dehydrogenation. However, in order to increase the efficiency of dehydrogenation, it is better to have a high energy density.If laser irradiation is performed at a high energy density, the gas contained in the thin film explosively generates and the thin film itself becomes The problem of destruction arises.

[0008] Particularly, regarding crystallization, conventionally,
For example, after forming a thin film of amorphous silicon and irradiating a laser beam to locally heat and melt the irradiation area,
A method is adopted in which the thin film is cooled and recrystallized by stopping the beam at the end of laser oscillation, and by repeating melting and cooling by irradiating the laser beam, as a result, polycrystals with large crystal grains are obtained. I try to get a film. At this time, in the semiconductor thin film crystallized to have a large grain size, the scattering of carriers can be reduced and the mobility of electrons in the film can be increased. Therefore, by forming a thin film transistor here, higher performance can be obtained. Transistor can be realized. Further, by forming a large number of thin film transistors in the crystallized semiconductor thin film, it is possible to finally construct a high-performance integrated circuit. Of course, this excimer laser neal method (ELA method) can be applied not only to semiconductors such as Si and Ge, but also to conductors and insulating films.

However, when the crystallization is performed using, for example, a surface laser as the energy source, complete uniformity of the energy source cannot be expected. In addition, for example, from the viewpoint of forming an amorphous silicon (a-Si) film, It is difficult to completely uniform the film quality such as thickness and crystallinity, and it is practically impossible to generate crystals of a uniform size over the entire irradiation surface. In order to realize crystallization of a uniform size over the entire irradiation surface, it is necessary to form nuclei more uniformly and more stably than nucleation by the conventional laser annealing method described above.

Therefore, the present invention provides a method of manufacturing a thin film, particularly a semiconductor, in which hydrogen in the thin film is reduced as in an electric furnace without hindering productivity and without causing breakage of the film. It is an object to provide a method for producing a thin film. Furthermore, the present invention provides a method of manufacturing a thin film capable of uniformly and stably forming nuclei even when the thickness and quality of the thin film fluctuates, and forming a polycrystalline film having a uniform size. The aim is to provide a method.

Another object of the present invention is to provide a semiconductor thin film and a semiconductor device manufactured by using such a manufacturing method. Still another object of the present invention is to provide a semiconductor thin film manufacturing method and a semiconductor thin film manufacturing apparatus for manufacturing a good quality semiconductor thin film with high productivity.

[0012]

According to a method of manufacturing a thin film of the present invention, a thin film containing a volatile gas is irradiated with an excimer laser having a pulse width of 60 nanoseconds or more to remove the volatile gas in the thin film. It is characterized by degassing. Preferably, the thin film is a film containing at least 2% of a volatile gas, particularly a semiconductor thin film such as an amorphous silicon film or a polycrystalline silicon film, for example, having a thickness of 1 nm or more. The thin film is formed by plasma CVD, low pressure CVD, normal pressure CVD, catalyst C.
It is formed by using one or more of VD, optical CVD, and laser CVD. For excimer lasers,
Irradiation may be a single type of laser irradiation, or at least two types of laser irradiation. The at least two types of laser irradiation may have different irradiation intensities, and include, for example, a laser irradiation that repeats irradiation of less than 300 mJ / cm ² a plurality of times and a laser irradiation that repeats irradiation of 300 mJ / cm ² or more a plurality of times. Can be. The pulse width is preferably 60 ns or more and 300 ns or less, more preferably 100 ns or more and 250 ns or less, and 120 ns or more and 230 ns or less.

According to another method of manufacturing a thin film of the present invention, the temperature of at least a part of the thin film containing a volatile gas in the thickness direction of the thin film is maintained at or below the recrystallization temperature of the thin film forming material. And irradiating the film with an excimer laser to degas the volatile gas in the thin film. Preferably, the temperature near the surface of the thin film at the time of excimer laser irradiation is lower than the recrystallization temperature of the thin film forming material. For example, when the material for forming the thin film is at least an amorphous silicon film or a polycrystalline silicon film, the temperature near the surface of the thin film is preferably in the range of 800 ° C. to 1100 ° C. Further, the thin film forming material has a structure including at least one of an amorphous silicon film and a polycrystalline silicon film, and the vicinity of the thin film surface is set to a temperature equal to or higher than the recrystallization temperature of the thin film forming material. The temperature of the deep portion and the deeper portion can be in the range of 800 ° C to 1100 ° C. The predetermined depth portion from the surface of the thin film is, for example, a portion having a depth of 10 nm from the surface, preferably 5 nm, and more preferably a portion having a depth of 3 nm.

The semiconductor thin film of the present invention is characterized in that the volatile gas is reduced by irradiating an excimer laser having a pulse width of 60 nanoseconds or more from a state containing a volatile gas. . Further, the semiconductor device of the present invention is characterized in that such a semiconductor thin film is provided on a substrate. Preferably, the substrate is a glass substrate.

Further, in the method of manufacturing a semiconductor thin film according to the present invention, after forming the semiconductor thin film on a substrate, the semiconductor film is irradiated with an excimer laser having a pulse width of 60 nanoseconds or more to remove volatile gas in the semiconductor thin film. Gas, and then crystallization of the semiconductor thin film is performed by irradiation with an energy beam. The energy beam is preferably a beam of an excimer laser. After the semiconductor thin film is formed on the substrate, the semiconductor film can be irradiated with an excimer laser without being exposed to the atmosphere. Further, after the excimer laser irradiation, an energy beam may be irradiated without being exposed to the air.

According to the semiconductor thin film manufacturing apparatus of the present invention, a first processing chamber capable of forming a semiconductor thin film and a substrate connected to the first processing chamber and placed in the processing chamber are irradiated with excimer laser light. A second processing chamber capable of having a pulse width of 60
The method is characterized in that volatile gas in the semiconductor thin film formed on the substrate is degassed by irradiating the excimer laser light for nanoseconds or longer. In the second processing chamber, the semiconductor thin film is preferably crystallized by irradiating an energy beam.

In the present invention, by using an excimer laser, degassing can be performed in an extremely short time as compared with the case where an electric furnace is used. Assuming that the pulse width (duration) of the excimer laser is 60 nanoseconds, the conventional 5
Unlike the irradiation of an excimer laser having a pulse width of about 0 nanoseconds or less, the amount of energy injected into the thin film per unit time is reduced. Therefore, before the heating of the thin film surface becomes excessive due to energy absorption on the thin film surface, the heat is dissipated in the depth direction of the thin film and the like, and the entire film can be uniformly heated. Therefore, volatile gas such as hydrogen in the thin film can be uniformly degassed.

In the invention in which the irradiation energy of the excimer laser is set so as to maintain the temperature of the thin film below the recrystallization temperature of the thin film forming material, the energy of the laser beam is absorbed near the surface of the thin film and converted into heat. But
Since the temperature of at least a part of the region of the thin film is lower than the recrystallization temperature of the material for forming the thin film, substantial melting does not occur near the surface of the thin film and in the film, and recrystallization does not occur. Therefore, volatile gas such as hydrogen in the thin film can be efficiently separated from the film and led out of the film. In this case, the crystallization temperature may be exceeded for the gas to escape immediately only at the very surface of the thin film. However, a portion having a predetermined depth from the surface, that is, a portion having a depth of, for example, 10 nm, preferably 5 nm More preferably, in a portion having a depth of 3 nm and a portion deeper than 3 nm, the temperature is maintained below the recrystallization temperature of the thin film forming material. However, in a more preferred embodiment, the irradiation energy is set so as to maintain the temperature of the thin film including the surface below the recrystallization temperature of the thin film forming material.

In the method and apparatus for manufacturing a semiconductor thin film according to the present invention, the excimer laser is irradiated to degas the volatile gas in the semiconductor thin film, and then the semiconductor thin film is crystallized by irradiating an energy beam. Aim. Since recrystallization is advanced in a state where the volatile gas is reduced, crystal grains can be enlarged. For example, by degassing and crystallizing a channel portion of a thin film transistor with each beam, high mobility can be achieved. Performance devices can be obtained.

In the above-described method, the basic idea is to degas the volatile gas contained in the thin film and then crystallize the thin film. Simultaneous conversion is the idea of the second invention of the present application. In the second invention, a thin film, especially a semiconductor thin film, is formed by intentionally containing hydrogen, for example, and the film is irradiated with an energy beam, particularly an excimer laser having a long irradiation time (duration time) per pulse. Thus, a method of crystallizing a thin film is used as a means for solving the conventional problem. In other words, when a thin film containing a volatile gas is irradiated with an excimer laser,
When at least the surface layer of the thin film is melted, the volatile gas contained in the film is released from the film, and the collected volatile gases are outgassed into microbubbles. When microbubbles are generated in the melted film, the thin film is locally cooled to remove heat of vaporization from the film, and crystal nuclei are selectively generated when the temperature falls below the crystallization temperature. At this time, since the gas mass in the film is small and the mean free path is long, the uniformity of the gas in the thin film is easy to increase, and the uniform formation of crystal nuclei is more uniform than the conventional simple laser annealing method. Performance can be improved.

According to the method for producing a thin film of the present invention based on the above concept, a thin film containing 2 atomic% or more of a volatile gas is irradiated with an excimer laser having a pulse width of 60 nanoseconds or more, and the volatile gas in the thin film is irradiated. And simultaneously crystallizing the thin film. In addition, the semiconductor thin film of the present invention is irradiated with an excimer laser having a pulse width of 60 nanoseconds or more from a state where the volatile gas is contained at 2 atomic% or more, and the volatile gas is reduced and crystallized. The method for manufacturing a semiconductor thin film is characterized in that a semiconductor thin film containing a volatile gas of 2 atomic% or more is formed on a substrate and then irradiated with an excimer laser having a pulse width of 60 nanoseconds or more. And removing the volatile gas in the semiconductor thin film and simultaneously crystallizing the semiconductor thin film.

In the method for manufacturing a thin film and the method for manufacturing a semiconductor thin film according to the present invention described above, for example, a semiconductor thin film containing a volatile gas is irradiated with an excimer laser so as to cover a surface layer region (about 10 nm) of the semiconductor thin film. The energy of the laser is absorbed and melted, and the volatile gas contained in this region is instantaneously vaporized and outgassed from the entire film surface instantaneously. On the other hand, the thin film in the region near the interface with the substrate is also heated by receiving heat conduction from the surface layer region and gradually begins to melt, but also in this case, the volatile gas in the film separates from the film and collects. Micro bubbles are formed at regular intervals to outgas. When microbubbles are generated in the melted thin film, heat of vaporization is taken from the film, the melted thin film is locally cooled, and crystal nuclei are generated before other regions. Since the gas in the film can be easily incorporated uniformly into the thin film at the stage of forming the thin film, the generation density of the microbubbles can be increased by the conventional excimer laser annealing to randomly grow nuclei at the interface between the substrate and the thin film. It can be formed more uniformly than the method. As described above, according to the present invention, at the time of excimer laser annealing,
Since the nuclei generated at the interface between the substrate and the thin film can be formed more uniformly, a polysilicon thin film having a uniform crystal size can be formed by a polysiliconization process in which the thin film is excimer laser-annealed. In the case of a thin film transistor (TFT) using, variations in characteristics between transistors can be suppressed as small as possible. As a result, it is possible to solve the problem that the performance of the device is dominated by the TFT having the lowest characteristic when using a TFT having a large variation in characteristics, and it is possible to provide a high-performance TEF device. .

In the above method, the irradiation energy intensity of the excimer laser is set to be equal to or higher than the threshold energy at which the thin film is crystallized. As an excimer laser,
For example, a XeCl laser is used. The irradiation energy intensity of the excimer laser at this time is specifically 250 to 45.
It is preferably 0 mJ. The thin film containing a volatile gas is, for example, a semiconductor thin film, and this semiconductor thin film includes an amorphous silicon film at least in part of the film. Such a semiconductor thin film is formed using any one of plasma CVD, low pressure CVD, normal pressure CVD, catalytic CVD, optical CVD, and laser CVD, and has a thickness of about 10 to 100 nm. Although the thin film contains a volatile gas, as constituent atoms of the volatile gas, in addition to a hydrogen atom, a fluorine atom, a chlorine atom, a helium atom, an argon atom, a neon atom, a krypton atom,
It may be a xenon atom or the like.

In the above-mentioned degassing and crystallization, it is preferable to irradiate the excimer laser a plurality of times. As a specific irradiation method, for example, the excimer laser is irradiated a plurality of times while shifting the irradiation position of the excimer laser. At this time, the excimer laser is irradiated a plurality of times while shifting the irradiation position of the excimer laser so that at least a part of each irradiation area overlaps. Alternatively, the excimer laser is irradiated a plurality of times while shifting the irradiation position of the excimer laser so that each irradiation area is in contact. Furthermore, an excimer laser whose energy intensity is spatially modulated may be applied to at least a part of an irradiation area of the excimer laser to be applied to the thin film while shifting the irradiation position. In this case, for example, the modulation is performed so that the irradiation energy intensity decreases on the excimer laser traveling direction side.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings. According to the method for producing a thin film of the present invention, a thin film containing a volatile gas has a pulse width of 60
The method is characterized in that the volatile gas in the thin film is degassed by irradiating an excimer laser for nanoseconds or longer, and the degassing and crystallization are performed simultaneously.

[First Embodiment] FIG. 1 shows a degassing apparatus used in a method of manufacturing a thin film according to a first embodiment. The laser degassing apparatus will be described. This apparatus is for reducing hydrogen gas, which is a volatile gas, contained in a semiconductor thin film 22 formed on a low heat-resistant insulating substrate 21 such as a glass substrate. A low heat resistant insulating substrate 21 having a semiconductor thin film 22 formed thereon is placed in a chamber 20. This laser degassing apparatus has a chamber 20
Laser oscillator 23 and attenuator (attenuator) outside
24 and an optical system 25 including a homogenizer. A stage 27 movable in the XY direction is provided in the chamber 20, and a low heat resistant insulating substrate 21 on which a semiconductor thin film 22 is formed is mounted on the stage 27. The laser oscillator 23 includes an excimer laser light source, and emits a laser beam 26 having a pulse width of 60 nanoseconds or more intermittently. The optical system 25 including the homogenizer receives the laser light emitted from the laser oscillator 23 via the attenuator 24, shapes the laser light so that each side has a rectangular cross section of 10 mm or more, and irradiates the semiconductor thin film 22.
The attenuator 24 adjusts the energy of the laser light emitted from the laser oscillator 23. The optical system 25 shapes the laser light into a rectangular cross section and adjusts the energy so that the energy is uniformly distributed in the rectangular cross section. The inside of the chamber 20 is maintained in an inert atmosphere such as nitrogen gas. At the time of irradiation with the laser light 26, the stage 27 moves so that the ends of the beam overlap each other, and irradiates the surface of the semiconductor thin film 22 intermittently.

Chamber 2 of this laser degasser
The semiconductor thin film 22 formed on the main surface of the insulating substrate 21 placed in the substrate 0 is a film formed by a plasma CVD apparatus, and when the semiconductor thin film 22 is an amorphous silicon film, a silane gas is used. Since film formation proceeds, the film contains hydrogen as a volatile gas. Note that even when the semiconductor thin film 22 is formed by a sputtering method or the like, a part of the atmospheric gas, a part of the target atoms, and the like may be taken in. The present embodiment is characterized in that such a volatile gas such as hydrogen is degassed by laser irradiation. In particular, the laser oscillator 23 used in the present embodiment has a pulse width of the laser light. The configuration uses an excimer laser of 60 nanoseconds or more. Conventional excimer lasers used for crystallization, etc., have a pulse width of less than 50 nanoseconds, and when used directly for degassing such as hydrogen, the volatile gas contained in the thin film explodes. However, there is a problem that the film is broken out by being led out of the film.
However, by using an excimer laser having a pulse width of 60 nanoseconds or more as in this embodiment, the semiconductor thin film 2
The degassing can be realized while preventing the destruction of the film without excessively increasing the temperature of the thin film surface.

An excimer laser having a pulse width of 60 nanoseconds or more used for the laser oscillator 23 is a semiconductor thin film 2
Various light sources can be used as long as the light source is an excimer laser light source capable of degassing hydrogen or the like without excessively increasing the temperature of the thin film surface of Ar ₂ or K ₂ .
r ₂ , Xe ₂ , F ₂ , Cl ₂ , KrF, KrCl, XeCl, XeF, XeBr,
XeI, ArF, ArCl, HgCl, HgBr, HgI, HgCd, CdI, CdBr,
ZnI, NaXe, XeTl, ArO, KrO, XeO, KrS, XeS, XeSe, Mg
One or two or more excimer lasers selected from Hg ₂ and Hg ₂ can be used.

If the pulse width of the excimer laser is 60 nanoseconds or more, the concentration of heat on the surface of the thin film can be reduced.
The preferable range is 60 nanoseconds or more and 300 nanoseconds or less, more preferably 100 nanoseconds or more and 250 nanoseconds or less, and still more preferably 120 nanoseconds or more and 230 nanoseconds or less. . The upper limit of the preferable range, 300 nanoseconds, is a range in which the current excimer laser emits a beam with a pulse width of 300 nanoseconds, and if the pulse width becomes too long, the energy density per unit area is reduced. It will be too low and the degassing efficiency will be reduced.

The condition that the pulse width of the excimer laser is 60 nanoseconds or more, in other words, the excimer laser is applied to the thin film containing the volatile gas so that the temperature of the thin film is maintained below the recrystallization temperature of the thin film forming material. Irradiates the gas and satisfies the condition for removing the volatile gas in the thin film.
By maintaining the temperature below the recrystallization temperature, the crystallization of the thin film does not start, and the degassing of the volatile gas proceeds efficiently. In particular, by setting the temperature of the region near the surface of the thin film or a portion deeper than the surface by a predetermined depth and the portion deeper than that to less than the recrystallization temperature of the thin film forming material, the vicinity of the thin film surface is prevented from being recrystallized. Degassing is achieved. When the thin film is, for example, an amorphous silicon film or a polycrystalline silicon film, since the crystallization temperature of silicon is about 1140 ° C., the temperature of the thin film during excimer laser irradiation is, for example, in the range of 800 ° C. to 1100 ° C. To be.

Next, referring to FIGS. 2A to 2E,
A method for manufacturing a thin film according to the present embodiment will be described. First,
As shown in FIG. 2A, an insulating substrate 1 such as glass, quartz, or sapphire is prepared, and an amorphous semiconductor thin film 2 is formed on its main surface by, for example, a plasma enhanced CVD method.
To form As the insulating substrate 1, in particular, in the present embodiment, a so-called white plate glass having low heat resistance may be used since an excimer laser is used as a light source. As an example, an amorphous silicon film is formed as the amorphous semiconductor thin film 2. However, when the amorphous semiconductor thin film 2 is formed using a plasma enhanced CVD method or the like, a thin film containing 10 atomic% or less of hydrogen is used depending on conditions. It is formed. The thickness of the amorphous semiconductor thin film 2 is, for example, about 50 nm, but a suitable thickness can be adjusted according to the characteristics of a device to be manufactured. The amorphous semiconductor thin film 2 mainly contains hydrogen as a volatile gas, and atoms constituting the volatile gas include a helium atom, an argon atom, a neon atom, a krypton atom,
Xenon atoms or the like may be used, or other atmospheric gas during CVD or film formation, or target atoms during sputtering. The content of the constituent atoms of the volatile gas is, for example, 2 atomic% or more, and when the film is formed by using the plasma enhanced CVD method as described above, initially contains 10 atomic% or less of hydrogen depending on the conditions. Formed as a hydrogenated thin film.

After forming such an amorphous semiconductor thin film 2, the insulating substrate 1 is mounted on the laser degassing apparatus as described above, and as shown in FIG. To form an irradiation region 4 on a part of the amorphous semiconductor thin film 2. The irradiation of the laser light 5 has a pulse width of 60 nanoseconds or more, and a preferable range is 60 nanoseconds or more and 300 nanoseconds or less, more preferably 100 nanoseconds or more and 250 nanoseconds or less. Preferably, it is set in a range from 120 nanoseconds to 230 nanoseconds. The excimer laser may be irradiated singly at an energy intensity of, for example, 350 mJ / cm ² , or may be irradiated at an energy intensity of 300 mJ / cm ² , for example, about 50 times. Irradiation of an excimer laser having a pulse width of 60 nanoseconds or more degass hydrogen and the like in the amorphous semiconductor thin film 2. Even when the amorphous semiconductor thin film 2 is initially formed as a thin film containing 10 atomic% or less of hydrogen, hydrogen and the like in the thin film are desorbed from the excimer laser irradiation, and the volatility thereof in the irradiation region 4 The concentration of the gas is reliably reduced.
In the case of an amorphous silicon film, by suppressing the hydrogen concentration to 8% or less, ablation caused by hydrogen released from the amorphous silicon film does not occur. Preferably, the rate is controlled from 2% to 5% or less.

Subsequently, as shown in FIG. 2C, the irradiation of the excimer laser is expanded to a wider range so that most of the amorphous semiconductor thin film 2 on the insulating substrate 1 becomes the irradiation region 4. . The irradiation of the excimer laser may be, for example, a stage in a chamber of a degassing apparatus that moves so that the ends of the beams overlap, and may irradiate the surface of the semiconductor thin film intermittently and sequentially. Irradiation may be performed in a line-sequential manner without being limited to such a plane-sequential manner. Further, the stage may be fixed and the beam side of the excimer laser may be scanned, or both the stage and the beam may be moved. In the irradiation region 4, hydrogen and the like in the thin film are separated and the concentration of the hydrogen and the like is surely reduced. For example, it is possible to form the amorphous semiconductor thin film 2 in which the hydrogen gas concentration in the film is less than 2 atomic%, for example. it can.

After such a degassing step, in the present embodiment, the amorphous semiconductor thin film 2 on the same insulating substrate 1 is annealed by a laser beam 7 of an excimer laser, and FIG. As shown in (1), recrystallization proceeds. At this time, the excimer laser is irradiated with an irradiation intensity higher than the crystallization energy of the material for forming the amorphous semiconductor thin film 2, for example, 500 mJ / cm ^2.
Singly or multiple times excimer laser irradiation. The amorphous semiconductor thin film 2 is irradiated by the excimer laser irradiation.
Is recrystallized, and the size of the crystal grains is increased to form a recrystallized region 6 made of a polycrystalline semiconductor thin film.

After forming the recrystallized region 6, as shown in FIG. 2E, the stage in the chamber is moved so that the beam ends overlap, and the amorphous semiconductor thin film 2 is removed. The surface of the semiconductor thin film is sequentially and intermittently irradiated while being moved together with the insulating substrate 1. In addition, a method of irradiating in a line-sequential manner is not limited to such a plane-sequential manner. Further, the stage may be fixed and the beam side of the excimer laser may be scanned, or both the stage and the beam may be moved. When the recrystallized region 6 is formed, since the volatile gas content, particularly the hydrogen content, of the semiconductor thin film 2 has already been reduced by the formation of the irradiation region 4, the explosion of the film can be prevented.

In this manufacturing method, the irradiation of the laser beam 5 for dehydrogenation and the irradiation of the laser beam 7 for recrystallization can be carried out by separate apparatuses. The energy of the apparatus may be changed so as to be continuously performed in the same chamber. Even when the chamber is divided into two, continuous processing may be performed without opening to the atmosphere.

The above is a description along the steps of the present embodiment. Here, the excimer laser irradiation of the present embodiment shows a more ideal temperature distribution in the semiconductor thin film as compared with the conventional excimer laser irradiation. This will be described with reference to FIGS.

FIG. 3 is a diagram showing a temperature distribution in a semiconductor thin film by irradiation with a conventional excimer laser, and shows a result of a simulation. In FIG. 3, the vertical axis represents temperature (K), and the horizontal axis represents distance (thickness of thin film) (nm).
The temperature distribution of this conventional excimer laser has an irradiation intensity of 350 mJ / cm ² , a pulse width of 30 ns,
The calculation is based on a substrate temperature of 300K. In FIG. 3, a plurality of curves respectively indicate the lapse of time (0.5 ns, 1.0 ns, 1.5 ns, 2.0 ns, 2.5 ns) after laser irradiation. The irradiation of the conventional excimer laser is a simulation based on, for example, laser data of Lambda.
The thickness of the semiconductor thin film assumed here is, for example, 40 nm, and the temperature distribution in the thickness direction of the semiconductor thin film shows an extremely steep fall as the thickness of the thin film increases. This means that when an excimer laser with a short pulse width is irradiated, the vicinity of the thin film surface is heated in a short period of time, but there is no appreciable increase in temperature inside or at the interface between the thin film and the substrate. However, it is difficult to obtain a degassing effect inside the thin film.

FIG. 4 shows that the pulse width of the present invention is 6
FIG. 9 is a diagram showing a temperature distribution in a semiconductor thin film by excimer laser irradiation for 0 ns or more, and similarly shows a result of a simulation. In FIG. 4, the vertical axis represents temperature (K), and the horizontal axis represents distance (thickness of thin film) (nm).
The temperature distribution was calculated assuming that the irradiation intensity was 550 mJ / cm ² , the pulse width was 150 ns, and the substrate temperature was 300 K. In FIG. 4, a plurality of curves indicate time lapses after laser irradiation (5 ns, 10 ns, 15 ns, 20 ns, 25 ns).
ns). By irradiation with an excimer laser having a pulse width of 150 ns, the inside of the thin film is kept at 1100 ° C. even though the surface has a temperature slightly lower than the crystallization temperature of about 1100 ° C. from a temperature distribution curve after e.g.
The temperature distribution gradually decreases from the surface of the thin film from about 800 ° C. to the position deeper in the thickness direction, and even at the interface between the semiconductor thin film and the insulating substrate 40 nm from the surface of the thin film,
Since the temperature is close to 800 ° C., effective dehydrogenation can be expected.

As described above, by using an excimer laser having a pulse width longer than that of the conventional laser light, the temperature of the thin film surface is not so increased, that is, the temperature of melting or recrystallization of the thin film forming material is reduced. The temperature inside the thin film can be raised at the same time while maintaining a low temperature surface side, and reliable dehydrogenation can be performed in all regions in the thickness direction of the thin film.

[Second Embodiment] Next, an example of an active matrix type display device as a semiconductor device using a thin film transistor manufactured according to the present invention will be described with reference to FIG. In this embodiment, the pulse width is 6
This is an example in which a semiconductor device is configured by dehydrogenating with an excimer laser of 0 nano or more and using the thin film as a channel. As shown, the display device includes a pair of insulating substrates 31 and 32 and an electro-optical material 33 held between the pair.
And a panel structure comprising: As the electro-optical material 33, for example, a liquid crystal material is used. The pixel array section 34 and the drive circuit section are integrally formed on the lower insulating substrate 31. The driving circuit section includes a vertical scanner 35 and a horizontal scanner 36.
And divided into A terminal 37 for external connection is formed at the upper end of the peripheral portion of the insulating substrate 31. Terminal 3
Reference numeral 7 is connected to a vertical scanner 35 and a horizontal scanner 36 via a wiring 38. A row-shaped gate wiring 39 and a column-shaped signal wiring 40 are formed in the pixel array section 34.
A pixel electrode 41 and a thin film transistor 42 for driving the pixel electrode 41 are formed at the intersection of the two wires. The gate electrode of the thin film transistor 42 is connected to the corresponding gate line 39, the drain region is connected to the corresponding pixel electrode 41,
The source region is connected to the corresponding signal wiring 40. The gate wiring 39 is connected to the vertical scanner 35, while the signal wiring 40 is connected to the horizontal scanner 36. The thin film transistor 42 for switching and driving the pixel electrode 41 and the thin film transistors included in the vertical scanner 35 and the horizontal scanner 36 are excimer lasers having a pulse width of 60 nanometers or more according to the method of the first embodiment, and the channel portion of the thin film is dehydrogenated. This is what was produced. Furthermore, in addition to the vertical scanner and the horizontal scanner, a video driver and a timing generator can also be integrated and formed in the insulating substrate 31.

[Third Embodiment] This embodiment is an example of a method for producing a thin film in which a second dehydrogenation (reducing volatile gas) step is added to the steps of the first embodiment.

With reference to FIGS. 6A to 6E and FIGS. 7F and 7G, a method of manufacturing a thin film according to this embodiment will be described. First, as shown in FIG.
Similarly to the above embodiment, an insulating substrate 11 such as glass (including so-called low-heat-resistant so-called white plate glass), quartz, or sapphire is prepared, and an amorphous semiconductor is formed on its main surface by, for example, a plasma enhanced CVD method. A thin film 12 is formed. The amorphous semiconductor thin film 12 is formed as a thin film containing, for example, more than 10 atomic% of hydrogen depending on the conditions of CVD, and the thickness of the amorphous semiconductor thin film 12 is, for example, 50 nm.
It is about.

After such an amorphous semiconductor thin film 12 is formed, it is mounted on the laser degassing apparatus as described above together with the insulating substrate 11, and as shown in FIG. 6 (b), a first laser of an excimer laser. Irradiation with light 15 forms an irradiation region 14 in a part of the amorphous semiconductor thin film 12. This first
The irradiation of the laser beam 15 has a pulse width of 60 ns or more, and a preferable range is 60 ns or more and 300 ns or more.
The range is set to be not more than nanoseconds, more preferably not less than 100 nanoseconds and not more than 250 nanoseconds, and further preferably not less than 120 nanoseconds and not more than 230 nanoseconds. The irradiation of the excimer laser is the energy intensity of which does not cause even explosion and thin without causing crystallization example 200 mJ / cm ² to 250 mJ / cm ^2. It can be performed singly, but this 200 mJ / cm ^{2 to} 25
At an energy intensity of 0 mJ / cm ² , for example, two to two times
The irradiation may be performed about 0 times. By irradiation with an excimer laser having a pulse width of 60 nanoseconds or more, hydrogen and the like in the amorphous semiconductor thin film 12 are degassed. Amorphous semiconductor thin film 1
Even when 2 is initially formed as a thin film containing more than 10 atomic% of hydrogen, hydrogen and the like in the thin film are desorbed from the excimer laser irradiation, and the concentration of the volatile gas in the irradiation area 14 is reliable. To be reduced. 200 like this
by laser irradiation energy intensity of mJ / cm ² to 250 mJ / cm ^2, it is possible to suppress the hydrogen concentration in the first 8% or less as the first step.

Subsequently, as shown in FIG. 6C, the irradiation of the excimer laser is expanded to a wider range, so that the amorphous semiconductor thin film 12 on the insulating substrate 11 is largely irradiated.
It is set to 4. The irradiation of the excimer laser may be, for example, a stage in a chamber of a degassing apparatus that moves so that the ends of the beams overlap, and may irradiate the surface of the semiconductor thin film intermittently and sequentially. Irradiation may be performed in a line-sequential manner without being limited to such a plane-sequential manner. Further, the stage may be fixed and the beam side of the excimer laser may be scanned, or both the stage and the beam may be moved. In the irradiation region 14, hydrogen and the like in the thin film are separated and the concentration of the hydrogen and the like is reliably reduced.

After the first degassing step, the second
In the degassing step, irradiation of the second excimer laser is performed. As shown in FIG. 6D, the first laser beam 15
Is further irradiated with the second laser beam 16 of the excimer laser to the irradiation region 14 irradiated with. The irradiation of the second laser light 17 has a pulse width of 60 nanoseconds or more,
The preferred range is 60 ns or more and 300 ns or less, more preferably 100 ns or more and 25 ns or less.
0 ns or less, and more preferably in the range of 120 ns or more and 230 ns or less. The energy of this excimer laser irradiation is set higher than that of the first excimer laser irradiation, for example, 300 mJ /
It is the energy intensity of cm ² to 350 mJ / cm ^2. It can be singular, but this 300mJ / c
The irradiation may be performed, for example, about 2 to 40 times at an energy intensity of m ^{2 to} 350 mJ / cm ² . By excimer laser irradiation with a pulse width of 60 nanoseconds or more,
Hydrogen and the like in the amorphous semiconductor thin film 12 are further degassed. Even when the amorphous semiconductor thin film 12 is initially formed as a thin film containing more than 10 atomic% of hydrogen, hydrogen and the like in the thin film remaining in the first degassing step are desorbed from excimer laser irradiation. Then, the concentration of the volatile gas in the irradiation area 17 of the second laser beam 16 is more reliably reduced. The second laser beam 16 may have the same laser light source as the first laser beam 15 and have a different energy intensity, or a different laser light source may be used.

Subsequently, as shown in FIG.
Of the amorphous semiconductor thin film 12 on the insulating substrate 11 is used as the irradiation region 17. The irradiation of the excimer laser may be, for example, a stage in a chamber of a degassing apparatus that moves so that the ends of the beams overlap, and may irradiate the surface of the semiconductor thin film intermittently and sequentially. Irradiation may be performed in a line-sequential manner as well as in the plane-sequential manner. Further, the stage may be fixed and the beam side of the excimer laser may be scanned, or both the stage and the beam may be moved. In the irradiation area 17, hydrogen and the like in the thin film are separated and the concentration of the hydrogen and the like is reliably reduced.

In the process shown in FIG. 6, after the first excimer laser irradiation is performed on the entire substrate,
Although the step of irradiating the entire substrate with the second excimer laser has been described, the first excimer laser is irradiated on a part of the substrate, and the second excimer laser is irradiated immediately after that, and the second excimer laser is irradiated. The combination of the irradiation of the first excimer laser and the irradiation of the second excimer laser may be sequentially spread over the entire substrate.

The irradiation region 17 of the same amorphous semiconductor thin film 12
Is annealed by the laser beam 19 of the excimer laser, and recrystallization proceeds as shown in FIG. The excimer laser irradiation at this time is performed with an irradiation intensity higher than the crystallization energy of the material for forming the amorphous semiconductor thin film 12, for example, 500 mJ / cm.
^{In step 2} , single or multiple excimer laser irradiation is performed.
By the irradiation of the excimer laser, the amorphous semiconductor thin film 12 is recrystallized, and the size of the crystal grains is increased to form a recrystallized region 18 made of a polycrystalline semiconductor thin film.

The formation of the recrystallized region 18 is thereafter performed
As shown in FIG. 7 (g), the stage in the chamber is moved so that the ends of the beam overlap each other, and the amorphous semiconductor thin film 12 is moved together with the insulating substrate 11 so that the surface of the semiconductor thin film is intermittently moved. Irradiate sequentially. In addition, a method of irradiating in a line-sequential manner is not limited to such a plane-sequential manner. Further, the stage may be fixed and the beam side of the excimer laser may be scanned, or both the stage and the beam may be moved. When the recrystallized region 18 is formed, the volatile region content, particularly the hydrogen content, of the semiconductor thin film 12 has been sufficiently reduced by the formation of the irradiation region 17 and the uniformity thereof has been reduced, thereby preventing the explosion of the film. can do. By such multi-step laser beam irradiation, volatile gas such as hydrogen can be reduced with good uniformity and reproducibility. In particular, when the initial hydrogen content exceeds 10 atomic%, volatile gas such as hydrogen having excellent uniformity and reproducibility while preventing explosion of the thin film in the degassing process by multi-step laser irradiation. Can be reduced.

FIG. 8 is a diagram showing the relationship between the number of shots and the hydrogen content in the film when lasers of different energy densities are irradiated in a degassing step by laser irradiation in multiple stages. Excimer laser is XeCl laser (wavelength 308)
nm), the pulse width is set from 150 nanoseconds to 200 nanoseconds, and the thickness of the formed amorphous silicon is about 40 nanoseconds.
nm. The vertical axis indicates the relative hydrogen content assuming that the hydrogen content at the time of formation on the insulating substrate by CVD or the like is 1. The horizontal axis is the number of shots of the XeCl excimer laser. As is clear from this graph, 200 m
When the excimer laser is irradiated with an energy intensity of J / cm ^{2 to} 250 mJ / cm ² , the hydrogen content tends to gradually decrease according to the number of shots, but the number of shots is generally in the range of 20 to 40 times Then, the content tends to converge to a content of about 0.7 to 0.6.
Therefore, the first laser irradiation of this embodiment is 200
mJ / cm ² to from an energy intensity of 250 mJ / cm ^2, after the first laser irradiation hydrogen content in the film will be settled between about 0.7 and 0.6. On the other hand, at 300 mJ / cm ² or more, for example, 350 mJ / cm ²
When the excimer laser is irradiated at an energy intensity near the single or small number of times, the hydrogen content in the film is greatly reduced by a single or small number of times. Meaning that the same level has been reached as the amount of reduction, further laser irradiation is not very meaningful. The second laser irradiation in this embodiment is performed at 300 mJ / cm ^{2 to} 350 mJ / cm ^2.
Because of the energy intensity, dehydrogenation is reliably performed by the second laser irradiation.

As described above, even when the second laser irradiation alone is used,
It can be said that the effect can be obtained in terms of degassing, but multi-step from the viewpoint of stably supplying a device having a semiconductor thin film and further ensuring uniformity of the hydrogen content in the film. Laser irradiation is effective.

[Fourth Embodiment] FIGS. 9, 10 and 1
A fourth embodiment of the present invention will be described with reference to FIG. The present embodiment relates to a semiconductor thin film manufacturing method and a semiconductor thin film manufacturing apparatus.

First, a semiconductor thin film manufacturing apparatus will be described with reference to FIG. FIG. 9 shows a schematic cross section of an example of the semiconductor thin film manufacturing apparatus according to the present embodiment. The main configuration is such that the CVD chamber 59 is connected to the laser irradiation chamber 65 via the transfer chamber 64.

The CVD chamber 59 is a processing chamber for forming a thin film on the substrate placed on the sample stage 62 by a CVD method. 61 is introduced to form a thin film on the substrate. The transfer chamber 64 is a transfer path for transferring the substrate processed in the CVD chamber 59 to the laser irradiation chamber 65 without opening the substrate to the atmosphere.
In particular, a gate 63 is provided between the CVD chamber 59 and the transfer chamber 64. For example, the gate 63 is closed while a thin film is formed by the CVD method, and a gas flows between the CVD chamber 59 and the transfer chamber 64. do not do.
The laser irradiation chamber 65 is a processing chamber for performing a degassing process by laser irradiation and an annealing process for recrystallization, and a transfer chamber 64 on a sample table 75.
The substrate transported from is loaded. Above the laser irradiation chamber 65, a quartz window 66 through which laser light is transmitted is provided. Through the quartz window 66, laser light is irradiated from an excimer laser 67 onto the upper surface of the substrate of the laser irradiation chamber 65. You. Above the laser irradiation chamber 65, a laser irradiation chamber 65 is provided.
There is also provided a gas inlet 68 for changing the internal atmosphere to a predetermined nitrogen atmosphere, for example, and an outlet 69 for discharging the processed substrate after the laser irradiation on the side wall of the laser irradiation chamber 65.

The excimer laser 67 disposed above the laser irradiation chamber 65 has a pulse width of 60 in particular.
In this embodiment, recrystallization by annealing is performed together with dehydrogenation by changing the energy density of irradiation in this embodiment. This excimer laser 67
Is provided so as to be able to move in the horizontal direction from a state in which the end of the substrate on the sample table 75 is opposed to the end of the substrate.

Next, a method of manufacturing a semiconductor thin film in which degassing and crystallization are performed using the semiconductor thin film manufacturing apparatus of FIG. 9 will be described with reference to FIGS.

First, as shown in FIG.
The substrate 51 is placed on the sample stage 62 in the chamber 59,
A film is formed by the CVD method with the gate 63 closed.
At the time of film formation by this CVD method, for example, silane gas and hydrogen gas are introduced from the gas inlet 60 as a CVD gas for forming an amorphous silicon film. These CVs
At the time of film formation together with the introduction of the D gas, plasma discharge is performed in the CVD chamber 59, and an amorphous silicon (a-Si) film 52 is stacked on the substrate 51. In the case of such plasma enhanced CVD, hydrogen is inevitably contained in the amorphous silicon film 52.

Subsequently, the plasma discharge is stopped, the supply of the CVD gas is stopped, and the inside of the CVD chamber 59 is evacuated. After the inside of the CVD chamber 59 is evacuated, the transfer chamber 64 and the laser irradiation chamber 65 are also evacuated, the gate 63 is opened, and the substrate 51 formed in the CVD chamber 59 is turned into an arrow shown in FIG. After being conveyed in the direction of 70 and passing through the inside of the transfer chamber 64, it reaches the laser irradiation chamber 65. In the laser irradiation chamber 65, the substrate 51 on which a film is formed is placed on a sample table 75. The gate 63 formed between the transfer chamber 64 and the CVD chamber 59 is closed after passing through the substrate 51. During the transfer of the substrate 51 from the CVD chamber 59 to the laser irradiation chamber 65, the atmosphere around the substrate 51 is not opened to the atmosphere, so that a short-time processing can be realized, and the substrate 51 is contaminated with unnecessary impurities. Probability is lower.

When the substrate 51 on which the hydrogen-containing amorphous silicon film 52 is formed is placed on the sample table 75 in the laser irradiation chamber 65, FIG.
As shown in (1), irradiation with a laser beam 72 for dehydrogenation is performed. The irradiation with the laser light 72 is, for example, irradiation with the laser light 72 having a pulse width of 60 nanoseconds or more from the excimer laser 67, and the energy density of the laser light 72 is such that the amorphous silicon film 52 is not melted or crystallized. For example, it is about 300 mJ / cm ² . Since the laser beam 72 from the excimer laser 67 does not collectively hit the entire surface of the amorphous silicon film 52 on the substrate 51, the excimer laser 67 is moved along the main surface of the substrate 51 by an arrow 71 in FIG.
Then, the entire surface of the amorphous silicon film 52 containing hydrogen is degassed. The laser irradiation chamber 6
5 is about twice the size of the substrate 51,
By configuring the 5 with an XY stage or the like, the sample table 75 may be moved in a horizontal plane while fixing the excimer laser 67 so that the entire surface of the laser beam 72 of the excimer laser 67 is irradiated. Further, both the laser beam 72 of the excimer laser 67 and the sample table 75 can be moved. Irradiation of the laser beam 72 for such degassing makes the amorphous silicon film 52
The amount of hydrogen contained in the gas is reduced, and, for example, the degassing of an electric furnace as low as 2 atomic% or less can be performed instantaneously.

Following this degassing process, the crystallization of the amorphous silicon film 52 is performed using the same excimer laser 67. The laser light 73 from the excimer laser 67 for this crystallization is, for example, about 500 mJ / cm ² ,
Dehydrogenation and degassing have already been performed by excimer laser 6
Since the laser beam 72 is used for the laser beam 72, the film can proceed while preventing explosion of the film. The laser light 73 from the excimer laser 67 for this crystallization is also indicated by an arrow 7 as shown in FIG.
Irradiation can be performed while moving the excimer laser 67 in one direction, and the entire surface of the amorphous silicon film 52 on the substrate 51 can be crystallized. Similarly to the laser irradiation for dehydrogenation, by configuring the sample stage 75 with an XY stage or the like, the sample stage 75 is moved in a horizontal plane while the excimer laser 67 is fixed, and the laser beam of the excimer laser 67 is moved. The entire surface 73 may be irradiated. In addition, both the laser beam 73 of the excimer laser 67 and the sample table 75 can be moved.

Finally, as shown in FIG. 11E, the discharge port 6 formed on the side of the laser irradiation chamber 65 is formed.
9 is opened, and the film-formed substrate 51 that has been subjected to the crystallization treatment together with the degassing treatment is taken out from the outlet 69.

From the above steps, the amorphous silicon film 52 on the substrate 51 is degassed and crystallized using the same excimer laser 67. In the conventional manufacturing method, it takes about two hours from the CVD apparatus to the laser annealing apparatus in order to degas in an electric furnace, and it is indispensable to open to the atmosphere. In the embodiment, the processing can be performed using the same semiconductor thin film manufacturing apparatus from the CVD step to the degassing step and the crystallization step, so that the productivity can be increased. In addition, since sufficient degassing is performed before crystallization, the explosion of the amorphous silicon film 52 can be prevented, and a high-quality crystalline semiconductor thin film can be supplied.

[Fifth Embodiment] FIG. 12 shows an example of a semiconductor thin film manufacturing apparatus according to a fifth embodiment. A substrate 81 is placed on a sample stage 80, and an amorphous silicon film 82 is formed on the substrate 81. A pair of excimer laser devices 83 and 8 are opposed to this amorphous silicon film 82.
4 are provided, each of which is movable in the direction of arrow 50. These excimer laser devices 83, 8
4 is a side on which the amorphous silicon film 82 is first irradiated with the laser beam 87;
As the laser beam 87 is degassed, the pulse width suitable for the dehydrogenation of more than 60 ns light, the energy density is, for example, 300 mJ / cm ² to 350 mJ / cm ^2. The other excimer laser device 84 generates a laser beam 88 which is irradiated subsequently to the laser beam 87 from the excimer laser device 83, and has an energy density of, for example, 500 mJ / cm ^{2 to} 600 mJ suitable for crystallization.
/ Cm ² . A pair of excimer laser devices 8
3, 84 can move in the direction of arrow 50, respectively.

A pair of excimer laser devices 83 and 84 are respectively indicated by arrows 5
As a result of moving in the zero direction, it is first degassed and subsequently recrystallized. At the time of this recrystallization, problems such as explosion of the film are prevented beforehand because the gas has already been degassed. In the example of FIG. 12, a pair of excimer laser devices 8
3 and 84 are described as moving in the direction of the arrow 50, but the substrate 51 side and the pair of excimer laser devices 8
3, 84 and the substrate 51 may both be moved.

[Sixth Embodiment] FIG. 26 is a view showing an example in which a semiconductor thin film manufacturing apparatus according to a fifth embodiment is configured to include a CVD chamber. The semiconductor thin film manufacturing apparatus according to the sixth embodiment has a main configuration in which a CVD chamber 91 is connected to a laser irradiation chamber 93 via a transfer chamber, and the configuration of the chamber itself is shown in FIG. Same as the device.

The CVD chamber 91 is a processing chamber for forming a thin film on a substrate placed on a sample stage 92 by a CVD method, and forms a thin film on the substrate by introducing a film forming gas. The laser irradiation chamber 93 is a processing chamber for performing a degassing process by laser irradiation and an annealing process for recrystallization, and a substrate 95 transferred from the transfer chamber is placed on a sample stage 94. . A quartz window through which laser light is transmitted is provided on the upper part of the laser irradiation chamber 93, and laser light from a pair of excimer laser devices 97 and 98 is applied to the thin film on the upper surface of the substrate of the laser irradiation chamber 93 through the quartz window. 96.

The excimer laser device 97 is a laser having a pulse width of at least 60 nanoseconds.
The thin film 96 on the upper surface of the substrate is irradiated with 9 and used for dehydrogenation. The other excimer laser device 98 irradiates a laser beam 100 to the thin film 96 on the upper surface of the substrate and animates it.
And recrystallize it. Each of the pair of excimer laser devices 97 and 98 can move in the direction of arrow 50,
As a result of the pair of excimer laser devices 97 and 98 respectively moving in the direction of the arrow 50, the amorphous silicon film 96 on 5 is first degassed and subsequently recrystallized. At the time of the recrystallization, problems such as explosion of the film are prevented beforehand because the gas has been degassed. FIG.
In the example of the third example, the pair of excimer laser devices 97 and 98 are described as moving in the direction of arrow 50. However, the substrate 95 side and both the pair of excimer laser devices 97 and 98 and the substrate 95 are moved. May be.

[Seventh Embodiment] A semiconductor thin film manufacturing apparatus according to this embodiment divides a laser beam from a laser light source by a beam splitter and irradiates one of the divided laser beams to degas the semiconductor thin film. The semiconductor thin film is crystallized by irradiating the other divided laser beam. As shown in FIG. 14, the configuration has an excimer laser device 55 for generating a laser beam having a single pulse width of 60 nanoseconds or more, and a beam splitter 56 for splitting the beam has a laser beam from the excimer laser device 55. Arranged on the beam of the beam.
One of the laser beams 46 split by the beam splitter 56 is directly applied to the semiconductor thin film 48 on the substrate 49, and the laser beam 46 is used for degassing the semiconductor thin film 48. The other laser beam on the side that is split and transmitted by the beam splitter 56 is reflected by a mirror 57, and the reflected laser beam 47 irradiates a semiconductor thin film 48 on a substrate 49. The laser beam 47 crystallizes the semiconductor thin film 48. In FIG. 14, the substrate 49
Is fixed on a sample stage 58, and in the present embodiment, the sample stage 58 moves in the direction of the arrow 50 to move the semiconductor thin film 48.
The degassing process by the laser beam 46 and the crystallization process by the laser beam 47 are performed over almost the entire surface of the substrate.

In this embodiment, a laser beam 46 having a low energy density for degassing is reflected by a beam splitter 56, and a laser beam 47 having a high energy density for crystallization is applied to the beam splitter 56. Although the light is transmitted, an optical system that outputs a laser beam having the opposite relationship may be provided. In the present embodiment, the sample stage 58 moves to promote degassing and crystallization of the thin film. However, a structure in which the laser device side moves or a structure in which both the structures move may be used. Further, in the present embodiment, the laser beam is divided into two. However, the present invention is not limited to this, and has a mechanism that divides the laser beam into three or more parts or separates the laser beam into portions that are further apart spatially. Is also good.

[Eighth Embodiment] In this embodiment, degassing and crystallization of a semiconductor thin film are simultaneously performed by irradiation with an excimer laser.

In this embodiment, since the intensity distribution of the laser light at the time of output from the laser device has a Gaussian distribution, it is passed through a homogenizer so that the intensity becomes uniform within the laser cross section. I do. This is further led to a slit so that the intensity of the laser is distributed in a box shape. Using a laser beam having a uniform laser intensity as described above, the two main and sub laser beams are adjacent to each other or the trailing edge (T
E) When a part of the sub laser beam is overlapped on the side, and the main laser beam stops,
Alternatively, the sub-laser beam irradiation is started before that.

At this time, in particular, the intensity of the sub-laser beam adjacent or overlapping the trailing edge on the rear side in the main laser beam traveling direction is set lower than that of the main laser beam. For example, the temperature of the film is lower than the Si crystallization temperature by the irradiation of the sub-laser beam,
It is desirable to set the temperature to at least about 1100 ° C. Further, the main laser beam is irradiated from above the sample, and the sub-laser beam is irradiated from below the substrate. Alternatively, the reverse is also possible. Furthermore, both lasers can be provided on the lower surface side of the substrate.

As described above, when the a-Si film on the substrate is subjected to laser annealing, the trailing edge side is rapidly cooled, so that it cannot be crystallized and re-a-Si is formed. The trailing edge portion (TE portion) of the region to be annealed by the irradiation is continuously irradiated with the sub-laser beam having a lower output than the main laser beam until the main laser beam is stopped. Thus, crystallization can be reliably performed. In addition, thermal discontinuity between the crystallized region and the crystallized region can be suppressed to a low level. In addition to the growth of crystal grains, prevention of crystal dislocation at the interface region with the crystallized region and prevention of crystal grains It can also be expected to have an effect of preventing the occurrence of intradefects in the inside.

In the conventional method of sequentially performing two laser irradiations, the first irradiation warms the interface between the substrate and the film under the a-Si film, so that the crystallization by the next irradiation is performed. Although it is described that the irradiation can be performed more stably, the end portion of the irradiation region is not escaped from the rapid cooling even by this method, and there is a concern about a-Si conversion at the irradiation end portion. In the present embodiment, on the other hand, effects such as preventing the end portion of the irradiation region from being rapidly cooled as described above, preventing a-Si formation, and facilitating the alignment with the crystallized region are obtained. Can be expected. Furthermore, in particular, by providing two lasers on the upper surface side of the substrate, it is possible to expect an effect that the configuration of the device becomes easy and that even if the substrate is opaque, it is possible to cope with it.

FIG. 16 is an electron micrograph (magnification: 20,000) of the semiconductor thin film produced as described above.
7 is an enlarged image (magnification: 50,000 times). The crystal grain size range of this semiconductor thin film is 60 to 200 nm, and the average grain size is 140 nm, indicating that the semiconductor thin film is a highly uniform polycrystalline film having uniform crystal grain sizes.

[Ninth Embodiment] In the ninth embodiment,
The main and sub two laser beams are positioned adjacent to or on the TE side of the main laser beam so as to partially overlap the sub laser beam, and the main laser beam is irradiated when the main laser beam is stopped or before the main laser beam stops Was set to start, and the time for cooling the film melted by the irradiation of the main laser beam, particularly the TE portion, was set as follows. That is, since the rate at which Si can be crystallized into a polycrystalline state instead of a-Si is a maximum of 20 nm / sec, when the film on the molten substrate is crystallized, the crystallization rate is maintained within 20 nm / sec. The irradiating conditions of the secondary laser beam, particularly the irradiation intensity, are set so that the crystallization can be performed by spending a time equal to or more than the value obtained by dividing the film thickness on the substrate by the above-mentioned crystallization speed of 20 nm / sec. Set.

[Tenth Embodiment] In this embodiment, when a film on a substrate is subjected to laser annealing, when a sub-laser beam is provided adjacent to or partially overlapping a main laser beam, The secondary laser beam is diverged or converged. An angle is provided between the sub laser beam and the main laser beam.

[0079]

As described above, in order to degas an amorphous silicon film or the like on a substrate, a relatively long pulsed laser beam having a pulse width of 60 nanoseconds or more is irradiated. Hydrogen and the like in the thin film are released, and the concentration of the hydrogen and the like is reliably reduced in the irradiation region. For this reason, even when laser irradiation with a high energy density is performed for crystallization subsequently, problems due to hydrogen and the like such as explosion of the film do not occur. In the present invention, degassing itself is a short-time treatment using an excimer laser,
Compared with a conventional process using an electric furnace, the time required for a significant manufacturing process can be shortened, and a semiconductor thin film and a semiconductor device to be manufactured can be manufactured with high productivity.

In particular, in the present invention, since the laser beam having a relatively long pulse width of 60 nanoseconds or more is irradiated, the energy density is 60 to 150 mJ / cm.
Effective degassing is possible without having to be as low as about ^2, and degassing can be achieved with good reproducibility and uniformity by performing a plurality of irradiations with different energy intensities.

On the other hand, in the present invention, in particular, a semiconductor thin film is formed by intentionally containing hydrogen, for example, and the film is irradiated with an energy beam, particularly an excimer laser having a long irradiation time (duration time) per pulse. By doing so, it is possible to simultaneously degas and crystallize the thin film,
The nucleus can be formed uniformly and stably even if the film thickness or film quality of the thin film fluctuates, and a polycrystalline film having a uniform size can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a degassing apparatus used in a method for producing a thin film according to a first embodiment of the present invention.

FIG. 2 is a process cross-sectional view for describing a thin film manufacturing method according to the first embodiment of the present invention in accordance with the process;
(A) is a step of forming an amorphous semiconductor thin film, (b) is a step of irradiating a laser beam for degassing, (c) is a continuation of the step of irradiating the laser beam, and (d) is a step of recrystallization. The laser light irradiation step, (e) is a continuation of the laser light irradiation step.

FIG. 3 is a diagram showing a temperature distribution in a thickness direction of a conventional excimer laser.

FIG. 4 is a diagram showing a temperature distribution in a thickness direction of an excimer laser according to the present invention.

FIG. 5 is a schematic perspective view showing an active matrix type display device using a thin film semiconductor device manufactured by the thin film manufacturing method of the present invention.

FIG. 6 is a process cross-sectional view for describing a thin film manufacturing method according to a third embodiment of the present invention in accordance with the process;
(A) is a step of forming an amorphous semiconductor thin film, (b) is a step of irradiating a first laser beam for degassing, (c) is a continuation of the step of irradiating the laser beam, and (d) is degassing. (E) is a continuation of the laser light irradiation step.

FIGS. 7A and 7B are process cross-sectional views for describing a method of manufacturing a thin film according to the third embodiment in accordance with the process, wherein FIG. 7F is a laser beam irradiation process for recrystallization, and FIG. This is a continuation of the light irradiation step.

FIG. 8 is a diagram showing the relationship between the hydrogen content in the amorphous silicon film and the number of shots of the excimer laser when irradiated with an excimer laser.

FIG. 9 is a schematic view illustrating a structure of a semiconductor thin film manufacturing apparatus according to a fourth embodiment of the present invention.

10A and 10B are cross-sectional views illustrating a method for manufacturing a semiconductor thin film according to a fourth embodiment of the present invention, together with a state in the apparatus, and FIG.
Shows a CVD step, (b) shows a substrate transfer step, and (c) shows a degassing step.

FIG. 11 is a cross-sectional view showing a method of manufacturing a semiconductor thin film according to a fourth embodiment of the present invention, together with a state in the apparatus, and (d).
Shows a crystallization step, and (e) shows a substrate discharging step.

FIG. 12 is a schematic view illustrating a structure of a semiconductor thin film manufacturing apparatus according to a fifth embodiment of the present invention.

FIG. 13 is a schematic diagram illustrating a structure of a semiconductor thin film manufacturing apparatus according to a sixth embodiment of the present invention.

FIG. 14 is a schematic view illustrating a structure of a semiconductor thin film manufacturing apparatus according to a seventh embodiment of the present invention.

FIG. 15 is a process cross-sectional view for explaining a conventional method of manufacturing a thin film, in which (a) shows a process of forming an amorphous semiconductor thin film,
(B) is a degassing step using an electric furnace, (c) is a laser beam irradiation step, (d) is a recrystallization step, and (e) is a continuation of the recrystallization step.

FIG. 16 is an electron micrograph (magnification: 20,000) of a semiconductor thin film produced according to the present invention.

FIG. 17 is an electron micrograph (magnification: 50,000 times) of a semiconductor thin film produced according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Amorphous semiconductor thin film 5 Laser light 6 Recrystallization area 15 First laser light 16 Second laser light

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Setsuo Sekii 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo F-term in Sony Corporation (reference) 4K030 BA29 BA30 BB03 CA06 CA12 DA09 JA01 JA10 JA11 JA13 JA18 5F052 AA02 BA02 BA11 BB03 BB07 DA01 DA02 DB01 DB02 DB03 EA15 FA19 JA01 5F110 AA26 AA30 BB02 DD02 DD03 DD04 GG02 GG13 GG16 GG25 GG43 GG44 GG45 PP03 PP04 PP05 PP06 PP13 PP26 PP29 PP35

Claims (52)

[Claims] 1. A method for producing a thin film, comprising irradiating a thin film containing a volatile gas with an excimer laser having a pulse width of 60 nanoseconds or more to degas the volatile gas in the thin film. 2. The method according to claim 1, wherein an excimer laser is applied to the film containing at least 2 atomic% of the volatile gas. 3. The method according to claim 1, wherein the irradiation with the excimer laser comprises at least two types of laser irradiation. 4. The method according to claim 1, wherein the at least two kinds of laser irradiation are two kinds of laser irradiations having different irradiation intensities. 5. The two types of laser irradiation having different irradiation intensities include laser irradiation in which irradiation of 300 mJ / cm ² or less is repeated a plurality of times and laser irradiation in which irradiation of 300 mJ / cm ² or more is repeated a plurality of times. A method for producing a thin film according to claim 4. 6. The pulse width is 60 ns or more and 30 ns or more.
The method for producing a thin film according to claim 1, wherein the time is 0 nanosecond or less. 7. The pulse width is not less than 100 nanoseconds and
The method for producing a thin film according to claim 6, wherein the time is 50 nanoseconds or less. 8. The method according to claim 1, wherein the pulse width is not less than 120 nanoseconds and 2
The method for producing a thin film according to claim 7, wherein the time is 30 nanoseconds or less. 9. The excimer laser is composed of Ar ₂ , Kr ₂ , Xe
_{2, F 2, Cl 2,} KrF, KrCl, XeCl, XeF, XeBr, XeI, Ar
F, ArCl, HgCl, HgBr, HgI, HgCd, CdI, CdBr, ZnI, Na
Xe, XeTl, ArO, KrO, XeO, KrS, XeS, XeSe, Mg 2, Hg
_2. The method according to claim 1, wherein the method comprises one or more lasers selected from the group consisting of two. 10. The method according to claim 1, wherein the volatile gas-containing thin film is a semiconductor thin film. 11. The method for manufacturing a thin film according to claim 10, wherein said semiconductor thin film includes at least a part of one of an amorphous silicon film and a polycrystalline silicon film. 12. The method according to claim 1, wherein the thin film is formed using one or more of plasma CVD, low pressure CVD, normal pressure CVD, catalytic CVD, photo CVD, and laser CVD.
0. The method for producing a thin film according to item 0. 13. The method according to claim 10, wherein said thin film has a thickness of 1 nm or more. 14. The thin film has at least one of hydrogen, helium, argon, neon, krypton, and xenon atoms as constituent atoms of the volatile gas. Item 3. The method for producing a thin film according to Item 1. 15. The volatile gas according to claim 14, wherein the content of the constituent atoms is at least 2 atomic%.
A method for producing the thin film according to the above. 16. A thin film containing a volatile gas is irradiated with an excimer laser so that a temperature of a region including at least a part of the thin film in a thickness direction is maintained at a temperature lower than a recrystallization temperature of a thin film forming material. A method for producing a thin film, comprising degassing the volatile gas in the thin film. 17. The method for producing a thin film according to claim 16, wherein the temperature near the surface of the thin film at the time of irradiation with the excimer laser is lower than the recrystallization temperature of the material for forming the thin film. 18. The thin film forming material includes at least one of an amorphous silicon film and a polycrystalline silicon film, and a temperature near a surface of the thin film is in a range of 800 ° C. to 1100 ° C. 18. The method for producing a thin film according to 17. 19. The thin film forming material includes at least one of an amorphous silicon film and a polycrystalline silicon film, and the vicinity of the thin film surface is set to a temperature not lower than the recrystallization temperature of the thin film forming material, and 17. The method for producing a thin film according to claim 16, wherein the temperature of the predetermined depth portion and a portion deeper than the predetermined depth range from 800 ° C. to 1100 ° C. 20. A thin film containing 2 atomic% or more of volatile gas is irradiated with an excimer laser having a pulse width of 60 nanoseconds or more, and the volatile gas in the thin film is degassed and at least a part of the thin film is removed. A method for producing a thin film, comprising crystallization. 21. The method for producing a thin film according to claim 20, wherein the irradiation energy intensity of the excimer laser is set to an energy not less than a threshold energy for crystallizing the thin film. 22. The method according to claim 20, wherein the excimer laser comprises an XeCl laser. 23. The method according to claim 22, wherein the irradiation energy intensity of the excimer laser is 250 to 450 mJ. 24. The method according to claim 20, wherein the thin film containing a volatile gas is a semiconductor thin film. 25. The semiconductor thin film according to claim 24, wherein at least a part of the semiconductor thin film includes an amorphous silicon film.
A method for producing the thin film according to the above. 26. The thin film is formed by using one or more of plasma CVD, low pressure CVD, normal pressure CVD, catalytic CVD, photo CVD, and laser CVD.
5. The method for producing a thin film according to 4. 27. The method according to claim 24, wherein the thin film has a thickness of 10 to 100 nm. 28. The thin film has at least one of hydrogen, fluorine, chlorine, helium, argon, neon, krypton, and xenon atoms as constituent atoms of the volatile gas. The method for producing a thin film according to claim 20, wherein: 29. The method according to claim 20, wherein the excimer laser is irradiated a plurality of times. 30. The method of manufacturing a thin film according to claim 29, wherein a plurality of types of irradiation energy intensities of the excimer laser irradiated a plurality of times are used. 31. The method according to claim 29, wherein the excimer laser is irradiated a plurality of times while shifting the irradiation position of the excimer laser. 32. The method of manufacturing a thin film according to claim 30, wherein the excimer laser is irradiated a plurality of times while shifting the irradiation position of the excimer laser so that at least a part of each irradiation area overlaps. 33. The method for producing a thin film according to claim 30, wherein the excimer laser is irradiated a plurality of times while shifting the irradiation position of the excimer laser so that each irradiation area comes into contact. 34. The method for manufacturing a thin film according to claim 20, wherein the spatially modulated excimer laser is irradiated to at least a part of an irradiation area of the excimer laser irradiated to the thin film while shifting the irradiation position. 35. The method according to claim 34, wherein the spatial modulation is a modulation of energy intensity. 36. The method for producing a thin film according to claim 34, wherein the irradiation energy intensity is modulated so as to decrease on the side of the excimer laser traveling direction. 37. A semiconductor thin film wherein the volatile gas is reduced by irradiating an excimer laser having a pulse width of 60 nanoseconds or more from a state containing the volatile gas. 38. From a state in which a volatile gas is contained at 2 at% or more, an excimer laser having a pulse width of 60 nanoseconds or more is irradiated to reduce the volatile gas and at least partially crystallize it. A semiconductor thin film, comprising: 39. A semiconductor thin film having a volatile gas content reduced from a state containing a volatile gas by irradiating an excimer laser having a pulse width of 60 nanoseconds or more on a substrate. Semiconductor device. 40. The semiconductor device according to claim 39, wherein said substrate is a glass substrate. 41. Irradiation with an excimer laser having a pulse width of 60 nanoseconds or more reduces the volatile gas content from a state in which the volatile gas content is 2 atomic% or more, and at least partially crystallizes the volatile gas. A semiconductor device comprising a semiconductor thin film formed on a substrate. 42. After forming a semiconductor thin film on a substrate, the semiconductor film is irradiated with an excimer laser having a pulse width of 60 nanoseconds or more to degas volatile gas in the semiconductor thin film. A method for producing a semiconductor thin film, wherein the method comprises the steps of: 43. The method according to claim 42, wherein the energy beam is an excimer laser beam. 44. The method according to claim 42, wherein after forming the semiconductor thin film on the substrate, the semiconductor thin film is irradiated with an excimer laser without opening to the atmosphere. 45. After forming a semiconductor thin film on a substrate, irradiating an excimer laser without opening to the atmosphere, and irradiating an energy beam after opening the excimer laser without opening to the atmosphere to crystallize the semiconductor thin film. The method for producing a semiconductor thin film according to claim 42, wherein the method is performed. 46. The method of manufacturing a semiconductor thin film according to claim 42, wherein the excimer laser is irradiated a plurality of times, and a part of each irradiation area is irradiated overlapping. 47. After forming a semiconductor thin film containing a volatile gas of 2 atomic% or more on a substrate, an excimer laser having a pulse width of 60 nanoseconds or more is irradiated to remove the volatile gas in the semiconductor thin film. A method of manufacturing a semiconductor thin film, wherein at least a part of the semiconductor thin film is crystallized at the same time as gasification. 48. The method of manufacturing a semiconductor thin film according to claim 47, wherein after forming the semiconductor thin film on the substrate, excimer laser is irradiated without opening to the atmosphere. 49. A first processing chamber capable of forming a semiconductor thin film, and a second processing chamber connected to the first processing chamber and capable of irradiating a substrate placed in the processing chamber with light from an excimer laser. A semiconductor having a pulse width of 60 nanoseconds or more in the second processing chamber and degassing volatile gas in a semiconductor thin film formed on the substrate by irradiating light of the excimer laser. Thin film manufacturing equipment. 50. The apparatus according to claim 49, wherein the semiconductor thin film is crystallized by irradiating an energy beam in the second processing chamber. 51. A laser beam from a laser light source is split by a beam splitter, one of the split laser beams is irradiated to degas the semiconductor thin film, and the other split laser beam is irradiated to split the semiconductor thin film. An apparatus for manufacturing a semiconductor thin film, characterized by crystallization. 52. A first processing chamber capable of forming a semiconductor thin film containing at least 2 atomic% of a volatile gas, and an excimer laser for a substrate connected to the first processing chamber and placed in the processing chamber. A second processing chamber capable of irradiating light; a volatile gas in a semiconductor thin film formed on the substrate by irradiating light of the excimer laser having a pulse width of 60 nanoseconds or more in the second processing chamber. Characterized in that at least a portion is crystallized at the same time as degassing.