JP2007042930A - Crystallization method, thin film transistor, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a crystallization process and a circuit forming process to be carried out through a process of performing an alignment operation using an alignment mark, even if a light irradiation process is carried out using a flash lamp. <P>SOLUTION: A workpiece 10 is composed of substrates 11 and 12 whose surfaces are formed of insulating material, a semiconductor thin film 13 formed on the substrates 11 and 12, and a capping layer 14 formed on the semiconductor thin film 13. An alignment mark 15 is formed on the workpiece 10 near a position where a prescribed TFT is formed by irradiation with a first laser ray L1. The alignment mark 15 is detected, and a predetermined crystallization position is irradiated with a second excimer laser ray L2 for the formation of a crystallized region 22 which is large in particle diameter. After the capping layer 14 is removed on a peripheral region containing the alignment mark 15, microcrystalline parts which are unevenly distributed in the crystal region enhanced in particle diameter are recrystallized by irradiation with the light of a flash lamp. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for crystallizing a semiconductor thin film, a thin film transistor, and a display device that can be applied to, for example, an active matrix flat panel display. In particular, the present invention relates to a crystallization method, a thin film transistor, and a display device that are suitable for alignment when forming a thin film transistor in a non-single crystal semiconductor thin film or in forming a thin film transistor in a later exposure process. .

  The semiconductor thin film crystallization technique is an important technique for forming a thin film transistor (hereinafter referred to as TFT: Thin Film Transistor) on an insulating substrate. As the TFT, a MOS structure transistor is usually used.

  A liquid crystal display device as a flat panel display is generally characterized by being thin, lightweight, low power consumption and easy in color display. Due to these features, liquid crystal display devices are widely used as displays for personal computers or various portable information terminals. In particular, in an active matrix liquid crystal display device, the TFT is used as a switching element of each pixel and an element constituting a driving circuit for driving each pixel TFT.

  The active layer of the TFT, that is, the carrier transport layer is composed of a silicon semiconductor thin film. Usually, a silicon semiconductor thin film for TFT is formed on an insulating substrate by, for example, a CVD method or a sputtering method. Such a silicon semiconductor thin film is an amorphous silicon (amorphous silicon) thin film or a polycrystalline silicon thin film composed of a large number of microcrystalline grains partitioned by crystal grain boundaries depending on conditions such as film forming temperature and film forming speed. .

  When the TFT is formed on this thin film, the former amorphous silicon semiconductor thin film has a carrier mobility that is one or two orders of magnitude smaller than that of the polycrystalline silicon semiconductor thin film. For this reason, a polycrystalline silicon semiconductor thin film is used for a TFT for a circuit requiring high speed.

  Next, a typical process for forming a silicon thin film made of polycrystalline silicon by a conventional method will be described. First, an insulating substrate such as glass is prepared. On the surface of the insulating substrate, for example, a SiNx or SiO2 film is formed as an undercoat layer or a buffer layer. Subsequently, an amorphous silicon semiconductor thin film is formed on the undercoat layer to a thickness of about 50 nm by, for example, a CVD method.

Thereafter, the amorphous silicon semiconductor thin film is subjected to a dehydrogenation process in order to reduce the hydrogen concentration in the amorphous silicon semiconductor thin film. Subsequently, the amorphous silicon semiconductor thin film is subjected to a melt crystallization process by an excimer laser crystallization method or the like. Specifically, an amorphous silicon semiconductor thin film is irradiated with an excimer pulse laser beam, the amorphous silicon semiconductor thin film is melted, and after the laser beam is cut off, the molten region is crystallized to be amorphous. This is a method of changing a porous silicon film into a polycrystalline silicon film.

  At present, at least an active region (channel region) of an n-channel type or P-channel type TFT is formed in a silicon thin film made of polycrystalline silicon thus obtained. The mobility of the TFTs thus manufactured (electron or hole mobility due to an electric field) is about 100 to 150 cm 2 / V sec for an n-channel TFT and 80 m 2 / V sec for a p-channel TFT. .

By using such a polycrystalline silicon thin film transistor, a driver circuit such as a signal line driver circuit or a scanning line driver circuit, and a pixel switching element can be formed over the same substrate. By integrating the TFTs of the display portion and the circuit portion, the manufacturing cost of the display device can be reduced, and the display device can be miniaturized.

  However, when using a polycrystalline silicon thin film crystallized by a conventional method, the electrical characteristics of TFTs are DA converters that convert digital video data into analog video signals, gate arrays that process digital video data, etc. It has not reached the point where it can be used for the signal processing circuit. In order to use a TFT in, for example, a DA converter or a signal processing circuit, a current driving capability twice to five times that of the TFT is required, and a field effect mobility is required to be about 300 cm 2 / V sec or more. .

  In order to further increase the functionality and added value of the display device, it is necessary to further improve the electrical characteristics of the TFT.

Furthermore, when a TFT is formed on a polycrystalline silicon thin film crystallized by a conventional method, a plurality of crystal grain boundaries are formed in the channel region of the TFT. The characteristics of carrier mobility of each TFT differ depending on the number of crystal grain boundaries and the arrangement of crystal grain boundaries.

  As a measure for improving the characteristics of the semiconductor thin film, for example, the crystallinity of the semiconductor thin film can be brought close to a single crystal. If the entire semiconductor thin film formed on the insulating substrate can be single-crystallized, the TFT formed on the single-crystallized semiconductor thin film has the same characteristics as a device using an SOI substrate studied as a next-generation LSI. Can be obtained. This attempt has been studied for more than 10 years as a three-dimensional device research project, but the single crystallization technique for the entire semiconductor thin film has not yet been established.

  As a method for crystallizing an amorphous silicon film, a technique has been proposed in which the crystal grain size of a crystal is grown so as to have an effect equivalent to that obtained when it is substantially single-crystallized (for example, Non-Patent Document 2). reference). This method is a phase-modulated excimer laser crystallization method in which an amorphous silicon film is irradiated with an excimer laser beam spatially modulated with a phase shifter to crystallize the irradiated region. In this phase modulation excimer laser crystallization method, the irradiated region of the amorphous silicon thin film is melted by giving a temperature distribution, and is grown in the lateral direction in the process of crystallization after the laser light is cut off, thereby increasing the size of the large particle size. This is a method for forming a crystallized region.

  That is, in this phase-modulated excimer laser crystallization method, the irradiation intensity of the excimer laser light on the plane of the amorphous silicon thin film has a strong gradient by the phase shifter, and the temperature gradient corresponding to this intensity distribution is changed to amorphous silicon. It is a crystallization method that occurs in a thin film. This temperature gradient causes the crystal growth of the amorphous silicon thin film from the low temperature portion to the high temperature portion in a direction parallel to the silicon thin film plane in the temperature decreasing process after the amorphous silicon thin film is melted. As a result, the phase-modulated excimer laser crystallization method can grow larger crystalline silicon grains than the conventional laser crystallization method.

  Further, this phase-modulated excimer laser crystallization method has a size that is at least larger than the area in which the TFT channel region is accurately formed at a predetermined position in the entire amorphous semiconductor thin film formed on the insulating substrate. It is a method having the characteristics that can be crystallized. The applicant has developed an industrialization technique for this technique.

In order to promote the growth of the crystalline silicon grains, the present applicant forms a capping layer such as silicon oxide (SiO 2 or SiO x), nitrogen silicon or the like on the amorphous semiconductor thin film, and then forms a phase. A crystallization technique based on a modulated excimer laser crystallization method has been developed and announced (Non-patent Document 3).

  According to this method, the size of the crystallized silicon grains is, for example, about several microns that can accommodate at least the channel region of one or a plurality of TFTs. Therefore, the TFT can obtain electrical characteristics satisfying the above-described requirements by being formed in alignment with the large crystalline silicon grain region thus formed.

  As described above, the phase modulation excimer laser crystallization method is an effective technique for obtaining large-sized crystal silicon grains. However, in the phase modulation excimer laser crystallization method, a microcrystal is first grown in a low temperature region where crystal growth starts, and further, this microcrystal is used as a seed to grow into a large crystal grain.

For this reason, the crystallized silicon thin film has a region composed of crystal silicon grains having a large grain size and a polycrystalline region composed of crystal silicon grains having a small grain size. Therefore, in order to form a TFT on a large-sized crystal silicon grain formed by adopting such a crystallization process, a TFT formed later is a region composed of a large-sized crystal silicon grain. It is necessary to accurately align and arrange them.

  In other words, when the TFT is formed in the polycrystalline region by deviating from the crystallized silicon region having the large grain size, the electrical characteristics, for example, mobility of the TFT is naturally significantly reduced. When such TFTs with reduced electrical characteristics are partially formed on, for example, a flat panel display, the display becomes a defective product, and the manufacturing yield is significantly reduced. When sequentially forming crystallized silicon regions with a large grain size for forming a plurality of TFTs at a predetermined position on the same substrate, it is sufficient to move the substrate only by a mechanical method on the order of sub μm. Position accuracy cannot be obtained.

  As means for coping with such an alignment problem, an attempt is made to form an alignment mark in advance in the crystallization process, and to execute the crystallization process and the TFT manufacturing process using the mark as an alignment reference. That is, this method is a method in which an alignment mark is formed in advance on the undercoat layer or the supporting substrate before crystallization, and crystallization processing is performed in accordance with this mark (Patent Document 1).

Flat panel display 1996 Nikkei Business Publications, December 11, 1995 issue p.174-p176 Surface Science Vol. 21, No. 5, p.278-p.287,2000 JP2003-264198A

  However, according to the above-described crystallization method, the region irradiated with the laser beam for crystallization includes a polycrystalline region composed of silicon particles having a small particle diameter from which the crystal is started, and crystalline silicon having a small particle diameter. There is a crystallized region with a large grain size having a single crystal with a large grain size grown from the grain. The polycrystalline region composed of the silicon grains having a small particle size is a region adjacent to the crystallization region and desired to have a large particle size.

For this reason, the present inventor has developed a technique for fusing a polycrystalline region made of crystalline silicon grains having a small grain size with crystalline silicon grains having a large grain size by flash lamp annealing or the like. The annealing with the flash lamp irradiates a large area at a time as compared with the laser beam.

Therefore, the annealing by the flash lamp is performed by irradiating a predetermined position of the amorphous semiconductor film with a laser beam through the capping layer by the phase modulation excimer laser crystallization method, and melting the irradiation region of the amorphous semiconductor film. Crystallize. Next, an irradiation process using a flash lamp is performed. The irradiation process using a flash lamp is a process of irradiating a crystallized substrate that has been crystallized by laser irradiation with flash lamp light, melting the irradiated region, and increasing the size of the above-mentioned small crystalline silicon grains. is there.

Thus, in the batch large area annealing method by flash lamp annealing, the crystallized region having a large grain size, the alignment mark, and the surrounding amorphous semiconductor film region are also annealed simultaneously.

Therefore, it was found that after flash lamp annealing, the amorphous semiconductor film region around the alignment mark and the alignment mark are difficult to distinguish. The reason is that the difference in crystallinity between the alignment mark made of crystalline silicon formed by the first laser beam and the surrounding region becomes small and it is difficult to identify. As a result, it is difficult to align with the alignment mark, and it becomes difficult to form the TFT by aligning with the crystallized region.

  The present invention has been made in response to the above problems, and even if a light irradiation process using a flash lamp is performed, alignment is performed using an alignment mark to perform a crystallization process, a TFT manufacturing process, and a circuit formation process. The present invention provides a crystallization method, a TFT, and a display device that can be used.

  The crystallization method of the present invention is a method of crystallizing a non-single-crystal semiconductor thin film, the step of forming a capping layer on the non-single-crystal semiconductor thin film, and the non-single-crystal semiconductor thin film by irradiating with a first laser beam. Forming an alignment mark at a predetermined position of the single crystal semiconductor thin film; and irradiating a second laser beam to a predetermined position of the non-single crystal semiconductor thin film aligned based on the alignment mark A crystallization step of forming a crystallization region, a step of removing the capping layer in a peripheral region including the alignment mark, and a step of irradiating a flash lamp light to the region including the crystallization region. It is characterized by.

  According to the present invention, it is possible to form at least the channel region of the thin film transistor in the crystallization region by aligning with the alignment mark.

The crystallization method of the present invention is characterized in that the second laser beam has a larger energy density than the first laser beam. According to the present invention, it is possible to further form an alignment mark having an arbitrary shape and to form a crystallized region having a larger grain size.

  The crystallization method of the present invention is characterized in that in the crystallization step, the non-single crystal semiconductor thin film is moved relative to the second laser, and the second laser is moved to the non-single crystal. The semiconductor thin film is sequentially scanned, and the second laser light irradiation is performed a plurality of times by alignment based on the alignment mark. According to the present invention, the crystallization region can be formed in a shape that facilitates the design and manufacture of the TFT.

  The crystallization method of the present invention is characterized in that the first laser light and the second laser light use the same laser light source and are changed to a predetermined energy density by an attenuator disposed in the optical path of the laser light. To be done. According to the present invention, an alignment mark can be formed by a crystallization apparatus, and subsequently, a crystallization region can be formed using the alignment mark as a reference.

The display device of the present invention is characterized in that at least a channel region of a TFT is provided in a crystallization region of a display circuit formation region.

  In the crystallization method of the present invention, a crystal region is formed by irradiating a laser beam through a capping layer provided on an amorphous or polycrystalline semiconductor thin film to form an alignment mark and positioning based on the alignment mark. Forming and removing a capping layer in a peripheral region including the alignment mark, and performing flash lamp light irradiation on a region including a crystal region having a large grain size by the second laser irradiation.

  According to the present invention, even if the light irradiation process using the flash lamp is executed, the crystallization process, the TFT manufacturing process, and the circuit forming process can be performed by aligning with the alignment mark.

  Next, a specific example of the embodiment of the crystallization method of the present invention will be described. This embodiment is an example in which an integrated circuit including a high-performance TFT can be formed at a desired position on an arbitrary substrate with an arbitrary size. Forming an integrated circuit including a high-performance TFT is to create an object to be processed having a novel structure.

Forming a high-function integrated circuit at a desired position is to form an alignment mark on a semiconductor thin film in advance and form a large grain size crystallized region based on the alignment mark. Forming at least the TFT of the integrated circuit in the crystallized region having a large grain size means that a highly functional integrated circuit is formed.

A feature of the process of this embodiment is that, in a crystallization process in which an annealing process using a flash lamp is performed, among the capping layer (protective layer) used in the alignment mark formation process by laser irradiation and the large grain size crystallization process, An annealing process using a flash lamp is performed after removing the capping layer (protective film) on and near the alignment mark.

  This crystallization process can ensure the identification of the alignment mark even after the crystallization process, and can be manufactured by aligning the TFT in the crystallization region based on the alignment mark. As a result, this crystallization process can form a high-performance TFT. The large grain size crystallization region is an area where a channel region of at least one TFT can be formed in the crystallization region. The high-function TFT means that the mobility of carriers is larger than that of a TFT formed in a polycrystalline semiconductor region because the TFT is formed in a crystallization region.

  The high distinguishability of the alignment mark is a result of performing the irradiation process with the flash lamp after removing the capping layer on the alignment mark. The irradiation process using such a flash lamp can suppress the temperature rise in the peripheral region including the alignment mark rather than the crystalline region covered with the capping layer, and the alignment mark is in an amorphous state or crystalline. This is because it is possible to ensure a low state of.

  Next, an embodiment of the above feature will be specifically described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view of an object to be processed for explaining a crystallization method and a TFT manufacturing method in the order of steps. 2A and 2B are a plan view and a cross-sectional view for explaining an example of the alignment mark in the step of FIG. The same parts are denoted by the same reference numerals, and detailed description thereof will be omitted because it is duplicated.

First, the manufacturing process of the to-be-processed object 10 is demonstrated with reference to Fig.1 (a). As the substrate of the object 10 to be processed, a support substrate 11 made of an insulating material made of, for example, a glass substrate, a quartz substrate, a plastic substrate, or the like is prepared. When applied to a liquid crystal display device, for example, an alkali-free glass substrate is preferably used as the support substrate 11.

The support substrate 11 of the present invention is not limited to an insulating material, and may be a semiconductor material or a metal material. As the semiconductor material of the support substrate 11, for example, a semiconductor substrate such as Si, Ge, SiGe, SiGeC, GaAS, GaP, InAS, GaN, ZnTe, CdSe, and CdTe can be used.

  Next, an insulating film 12 as an undercoat layer having a film thickness of, for example, about 500 nm is formed on the support substrate 11. The insulating film 12 is formed of, for example, a laminated film of a SiN film and a Si02 film, and is formed using, for example, the PEDVD method. The insulating film 12 is an undercoat layer of the semiconductor thin film 13, and prevents unwanted impurities from diffusing from the supporting substrate 11 such as glass to the semiconductor thin film 13 formed thereon, and is melt crystallized. Sometimes it also has a heat storage effect on the heat generated in the semiconductor thin film 13. As for the insulating film 12, a single kind of Si02 film, for example, may be formed.

  Next, a non-single crystal semiconductor thin film is formed on the insulating film 12. As this non-single-crystal semiconductor thin film, an amorphous or polycrystalline semiconductor thin film 13 is formed by using a known film forming technique such as a CVD method such as PECVD method or LPCVD method or a sputtering method. The film formation process of the semiconductor thin film 13 is, for example, a thermal decomposition process of monosilane SiH4.

The semiconductor thin film 13 is, for example, an amorphous silicon thin film having a thickness of about 30 to 200 nm, and more preferably about 50 to 100 nm. The semiconductor thin film 13 is not limited to a silicon thin film, and a physically appropriate semiconductor thin film 13 such as a Ge, SiGe, or SiGeC thin film can be used. The semiconductor thin film 13 is formed on the entire surface of the insulating film 12.

  Further, as shown in FIG. 1A, a protective film as a so-called capping layer 14 having a thickness of, for example, about 300 nm is formed on the entire surface of the amorphous semiconductor thin film 13. The capping layer 14 may be composed of, for example, SiO2, SiN film, SiON film, SiOx (x = 1 to 2) or a laminated structure film thereof. The insulating film 12 and the capping layer 14 also have a heat storage effect that reduces the laser irradiation power for melting the semiconductor thin film 13 and delays the cooling rate of the semiconductor thin film 13. This heat storage effect slowly lowers the temperature of the melted portion when the incidence of laser light on the melted semiconductor thin film 13 is stopped, and contributes to crystallization of a large grain size. In this way, the workpiece 10 is formed.

  Next, the process of forming the alignment mark 15 will be described with reference to FIG. An alignment mark 15 for determining the position of the crystal region and the formation position of circuit elements such as TFTs is formed on a part of the semiconductor thin film 13 by a phase modulation excimer laser crystallization method described below. The alignment mark 15 is formed in the semiconductor thin film 13 which is the lower layer of the capping layer 14 by irradiating a laser beam through the capping layer 14 to crystallize a predetermined region of the semiconductor thin film 13. This alignment mark 15 can also be used in the process of forming the TFT after crystallization.

  The alignment mark 15 can also be used for alignment in the process of bonding the substrates 91 and 92 to each other via a frame-shaped sealing material 118 in order to assemble a liquid crystal display device (see FIG. 9B). it can. Further, the alignment mark 15 can be used in, for example, alignment in a scribing process for dividing and using the insulating substrate 11 of FIG. 8 into a plurality of smaller substrates.

The alignment mark 15 can also be used as a reference for determining a lithographic mask position when a semiconductor element such as a TFT is formed on the semiconductor thin film 13, for example. As the alignment mark 15, an alignment mark necessary for a lithographic process in a subsequent TFT manufacturing process may be separately formed in the first (first) laser irradiation process.

  The alignment mark 15 further uses a mask or phase shifter 41 (FIG. 3) for forming the alignment mark 15 as shown in FIG. 2 (referred to as an alignment formation mask or shifter in this specification). Can do. Since the alignment mark 15 is formed on the semiconductor thin film 13 and has high discrimination, the alignment mark 15 can be used in a later process.

Prior to the crystallization step, the alignment mark 15 is formed by the first irradiation with the laser light L1 shown in FIG. This laser irradiation is called first laser irradiation. The laser light L1 is preferably homogenized light and has a two-dimensionally uniform light intensity.

The mask 17 for forming the alignment mark 15 is configured as shown in FIG. 2, for example. That is, a metal thin film 19A such as a chromium thin film having a thickness of 100 nm to 300 nm is formed on a transparent substrate 18 such as a glass substrate. The metal thin film 19A is etched into the shape of the alignment mark 15, for example, a cross shape, to form a penetrating portion 19B that transmits incident light.

By providing such a mask 17 in the laser beam path of the crystallization apparatus, an image of the mask 17 that has passed through the mask 17 is formed on the surface of the support substrate 11. Laser light transmitted through the through-hole 19B of the mask 17 and the capping layer 14 of the support substrate 11 enters the semiconductor thin film 13 and is absorbed by the semiconductor thin film 13. As a result, the semiconductor thin film 13 heats the semiconductor thin film 13 having a shape corresponding to the shape of the penetrating portion 19 </ b> B, thereby forming a crystallized region in the semiconductor thin film 13. The crystallized region is optically distinguishable because it has an optical characteristic different from that of an amorphous region which is a non-heated portion. That is, it is effective as the alignment mark 15. The arrangement control of the mask or phase shifter 41 for forming the alignment mark is performed by the alignment mark detection device 88 of FIG. 3 and a mask or phase shifter arrangement control mechanism (not shown).

  The shape of the alignment mark 15 can be appropriately selected in addition to the cross-shaped mark as shown in FIG. 2, and is not limited to the cross-shaped shape. In addition to the metal thin film 19A that does not transmit laser light, the mask 17 can be formed using a material that absorbs laser light, such as a silicon nitride film, as the light shielding material for the mask 17.

Moreover, the alignment mark 15 can also be formed using the phase shifter 41 which modulates the irradiation intensity of a laser beam to position (mark shape). When the phase shifter 41 is used, the alignment mark 15 can be formed of two or more kinds of marks having different reflected light intensities by the amorphous semiconductor film 13. The two or more types of marks having different reflected light intensities are composed of, for example, the surface of the amorphous semiconductor film 13 and a region where the amorphous semiconductor film 13 is changed by irradiation with laser light. It means that there are at least two types of portions where the surface of the film 13 has changed.

  In the crystallization process after the alignment mark forming process, it is desirable to execute the alignment marking and crystallization process by using a phase modulation excimer laser crystallization apparatus described below in order to simplify the manufacturing apparatus and process. That is, the process of forming the alignment mark 15 and the crystallization process described below are preferably performed continuously. When forming the alignment mark 15 on the amorphous silicon thin film 13, it is desirable to ensure an accurate contour and an optical difference between the peripheral portion.

For example, XeCl (wavelength 308 nm), KrF (wavelength 248 nm), or the like can be used as an excimer laser light source that shares the crystallization step described below and the step of forming the alignment mark 15. As the alignment mark 15 formed on the amorphous silicon thin film 13, a pattern in which a crystallized region is formed in a cross shape, for example, is optimal. That is, the alignment mark 15 is a mark crystallized in a cross shape on the amorphous silicon thin film 13.

The crystallized alignment mark 15 can be clearly distinguished from the amorphous silicon thin film 13. Formation of the alignment mark 15 by crystallization forms a crystallized mark display portion by setting the fluence of the irradiation laser beam to, for example, about 0.3 to 1.0 J / cm 2 at which the irradiation region melts.

  Next, the alignment mark 15 formed on the amorphous silicon thin film 13 is detected through the capping layer 14 and aligned with the alignment mark 15 to execute a laser crystallization process. Since the capping layer 14 is a transparent insulating film such as a silicon oxide film (SiO 2 film), the alignment mark 15 can be detected.

For example, as shown in FIG. 1C, the laser crystallization process is performed using a phase modulation excimer laser crystallization method which will be described in detail later. In this laser crystallization process, the surface of the capping layer (protective film) 14 is irradiated with, for example, excimer laser light L2 having a light intensity distribution as shown by a curve 46 in FIG. This laser irradiation is a second laser irradiation (FIG. 1C) following the first laser irradiation (FIG. 1B) for forming the alignment mark 15.

The irradiation position of the second laser irradiation (FIG. 1C) is set based on the alignment mark 15 formed in advance on the semiconductor thin film 13 from the first laser irradiation (FIG. 1B). In the second laser irradiation step, an example of the size and shape of the portion irradiated with one pulsed laser beam is 2 mm square. For this reason, the support substrate 11 is controlled to move so that the irradiation position on the support substrate 11 is selected based on the alignment mark 15.

The irradiation position by the second laser irradiation (FIG. 1C) on the support substrate 11 is a predetermined position corresponding to a switching circuit portion provided at each pixel position of the active matrix liquid crystal display device, for example. That is, in the second laser irradiation, the crystallized region 22 is formed in the amorphous semiconductor film 13 having a large area, for example, 1 m square, by irradiating the laser beam in a matrix. Since the second laser irradiation needs to melt the irradiation region of the semiconductor thin film 13, it requires a larger energy density than the first laser irradiation, and the fluence is a pulse of about 0.3 to 1.0 J / cm 2, for example. Laser light irradiation.

  In the second laser irradiation step, the laser light irradiation region of the amorphous semiconductor thin film 13 by the excimer laser light L2 is mostly melted, and the crystal grain size is increased in the temperature lowering process after the laser light is blocked. Is converted into the conversion area 22. For this reason, for example, the excimer laser beam L2 having a light intensity distribution in the reverse peak pattern for large grain size crystallization as shown in FIG. 4B is irradiated to the semiconductor thin film 13 through the capping layer 14. A temperature distribution according to the light intensity distribution is formed. The region irradiated with the excimer laser beam L2 of the semiconductor thin film 13 is heated to a melting point or higher and melted.

In the temperature lowering process after the laser beam is cut off, the temperature gradually decreases due to the heat storage effect of the capping layer 14 and the base film 12, and the freezing point moves laterally from the low temperature side to the high temperature side of the above temperature distribution to increase the particle size Crystallize.

In the subsequent crystallization process, crystals grow according to the temperature gradient. The size of the crystallized region is, for example, a crystal grain having an area sufficient to form at least a channel region of the TFT. In the vicinity of the crystallized region having a large particle size, there is an adjacent polycrystalline region made of silicon particles having a small particle size.

  Next, an annealing process using flash lamp light is performed. The feature of this process is that, as shown in FIG. 1D, the portion where the alignment mark 15 is formed and the capping layer 14 in the vicinity thereof are removed, and annealing is performed while leaving the capping layer 14 in other regions remaining. is there. This annealing process is characterized by a process of avoiding deterioration of the identification of the alignment mark 15 in the crystallization process of the polycrystalline region made of the silicon grains having a small particle diameter.

The surface of the alignment mark 15 and the amorphous semiconductor thin film 13 exposed by removing the alignment mark 15 and the capping layer 14 in the vicinity thereof are directly irradiated with flash lamp light for annealing. That is, as shown in FIG. 1D, the capping layer 14 in the peripheral region including the region of the alignment mark 15 is removed using a normal lithographic and etching method.

In the flash lamp annealing step, as shown in FIG. 1 (e), the flash lamp light is irradiated to the object 10 to recrystallize the microcrystalline portion unevenly distributed in the crystallized region having a large particle size. The area irradiated by one flash lamp can be significantly increased as compared with the area irradiated by the laser beam.

As a result of the annealing with the flash lamp light L3, the polycrystalline region having a small grain size formed in the vicinity of the crystallized region crystallized to have a large grain size in the second laser irradiation step grows and grows in size. Is done. In other words, as a result of irradiation heating with the flash lamp, the microcrystalline region in which the crystallization region 21 is unevenly distributed is recrystallized and reduced.

At this time, in the peripheral region including the region of the alignment mark 15, since the capping layer 14 is peeled off, the temperature rise is suppressed even when irradiated with the flash lamp light L <b> 3, so that the distinguishability of the alignment mark 15 is ensured. In other words, since the alignment mark 15 and its peripheral region have no heat storage effect because the capping film 14 is removed, the temperature rise is suppressed more than the region of the crystallization region 21, and the alignment mark 15 and its peripheral region The difference from the crystallinity is ensured, and the distinguishability is ensured.

Next, an example of annealing using a flash lamp will be described with reference to FIG. FIG. 5 is a cross-sectional view of a flash lamp annealing apparatus 59 that performs an annealing process using a flash lamp.

An airtight container, for example, a vacuum container 60 for storing the object to be processed 10 to be annealed by the flash lamp 63 is provided. The vacuum vessel 60 is provided with an exhaust port 61 connected to an exhaust pump (not shown). At the bottom of the vacuum container 60, a stage 62, for example, a square plate plate, is provided for supporting the loaded object 10 at a predetermined position. A lamp chamber 64 in which, for example, a plurality of rod-shaped xenon flash lamps 63 are housed as a heat source for annealing the object to be processed 10 is provided on the ceiling portion on the vacuum vessel 60. Above the xenon flash lamp 63 in the lamp chamber 64, a reflector 65 for reflecting the lamp light emitted upward in the direction of the workpiece 10 is disposed.

  Between the vacuum vessel 60 and the lamp chamber 64, a light transmitting plate 68 through which the flash lamp light emitted from the xenon flash lamp 63 in the chamber 64 is transmitted with low loss is provided, and an annealing device 59 is configured. Yes. The translucent plate 68 is a transparent body such as quartz having transparency of light in the visible region from ultraviolet rays, for example. A preheating means may be built in the stage 62 for preheating (temperature, for example, 100 to 550 degrees Celsius).

The xenon flash lamp 63 is a quartz tube in which xenon gas is sealed and an anode and a cathode connected to a capacitor are arranged at both ends, and electricity stored in the capacitor of the drive power circuit flows into the quartz tube. At that time, xenon gas is heated by Joule heat, and light is emitted. The xenon flash lamp 63 has a feature that it can irradiate extremely strong light as compared with a continuously lit light source because the electrostatic energy stored in advance is converted within a short pulse width of 0.1 ms to 10 ms.

The pulse width of the flash lamp 63 is desirably 0.5 to 2 ms. The flash lamp 63 has good controllability, and the annealing process is usually completed with one flash for one workpiece 10. In this annealing step, one-time irradiation can minimize the thermal damage of the semiconductor thin film 13 and can obtain a good result with improved throughput. The annealing process using a flash lamp may be performed a plurality of times in order to improve crystallinity.

Further, it is desirable that the emission spectral characteristics of the xenon flash lamp 63 be controlled to control the voltage, current density, gas pressure, inner diameter of the lamp, etc., and have high intensity in the visible region from ultraviolet rays having a high silicon absorption coefficient. Specifically, the emission condition range of the xenon flash lamp 63 for obtaining an ultraviolet emission intensity effective for crystallization of silicon when used in this experiment was a current density of 3000 A / cm 2 to 10000 A / cm 2. The xenon flash lamp 63 is desirable for the annealing process because the plasma temperature rises by increasing the current density and the ratio of the energy density of short wavelength components increases.

  As a processing atmosphere of the annealing (heating) step, it is desirable to perform in a vacuum or an atmosphere made of an inert gas. However, the present invention is not limited to such a method. In xenon flash lamp irradiation, the base region of triangular crystal grains formed by laser irradiation becomes a seed crystal, and small grain crystals and strip-shaped crystal grains also formed by laser irradiation are remelted from the seed crystal. Crystal grows. Therefore, crystal grains having a rectangular surface shape are formed by irradiation with a xenon flash lamp.

In this way, the region crystallized by the annealing step was substantially square, and the crystallinity was good enough to be the same as a single crystal. In order to form crystal nuclei by controlling the position, phase-modulated laser irradiation is necessary, but it is not always necessary to use spatially modulated laser light in the secondary expansion process of the crystal grain size.

Therefore, the annealing by the xenon flash lamp 63 is capable of more uniform light irradiation than the annealing by the laser beam, and has the advantages of high productivity such as controllability, uniformity, throughput, and maintainability, and an inexpensive apparatus. is there. Since the pulse width of the xenon flash lamp 63 is short as described above and the pulse width and emission spectral characteristics can be controlled to some extent, there is an advantage that it is easy to optimize the temperature rise of the silicon film in consideration of the influence on the base substrate. is there.

In this way, heating irradiation by the flash lamp 63 is performed. As a result, the microcrystalline region unevenly distributed in the crystallization region 21 is recrystallized and reduced. However, since the alignment mark 15 and its peripheral region have no heat storage effect because the capping layer 14 is removed, the temperature does not rise above the region of the crystallized semiconductor thin film 13, and the alignment mark 15 and its peripheral region An optical difference in crystallinity is ensured, and discrimination is ensured.

  Next, an element isolation process between the thin film transistors is performed. That is, as shown in FIG. 1F, the recrystallization region 22 is exposed by etching away the capping layer 14 on the amorphous semiconductor thin film 13.

Next, a separation step of the recrystallization region 22 is performed for each element (TFT) forming unit in order to separate the elements.

When the alignment mark 15 is used in the process of forming a TFT or the like, the region of the alignment mark 15 can be left without being etched as shown in FIG. If this alignment mark 15 is not used in a later process, the alignment mark 15 can be removed. In the crystallization region 22, at least a portion where a channel region (active region) of the TFT is formed is designed to be disposed in the crystallization region having a large grain size. In other words, the manufacture of the TFT or the like is to manufacture at least a channel region of the TFT in the recrystallization region 22 with the alignment mark 15 as a reference.

  Next, a manufacturing process of the TFT will be described with reference to FIG. As a specific example, FIG. 1G shows a cross section of two TFTs 23 formed in the recrystallized region 22 and having the same structure. For forming these TFTs 23, a generally known TFT manufacturing method can be applied.

In FIG. 1G, a gate insulating film 27 such as a SiO 2 film is formed on the surface of the recrystallized region 22. A gate electrode 28 is formed on the gate insulating film 27. A source region 24 and a drain region 26 are formed in the crystallized region 22 by ion implantation of impurities using the gate electrode 28 as a mask. Thereafter, the source region 24 and the drain region 26 are annealed for activation. As a result, a channel region (active region) 25 is formed in the recrystallized region 22 below the gate electrode 28 between the source region 24 and the drain region 26.

Next, an interlayer insulating film 31 such as a SiO2 film is formed. Contact holes are formed on the source region 24 and the drain region 26 of the interlayer insulating film 31. In each contact hole, a conductive material is buried to form a source electrode 29 and a drain electrode 30, respectively. In this way, the TFT 23 is configured. Although the specific example in which the TFT 23 is formed is shown in the above example, it goes without saying that other than the TFT 23, for example, a capacitor (capacitor), a diode, or the like can be formed in the recrystallization region 22.

  Next, an embodiment of a phase modulation type laser crystallization apparatus for executing the crystallization step of FIG. 1C will be described with reference to FIG. The crystallization apparatus 70 uses an excimer laser 71 (for example, XeCl, KrF) as a laser light source, but is not necessarily limited to these excimer lasers. An attenuator 73 for controlling the energy density of the laser beam 72 and a homogenizing optical system 74 for making the light intensity of the laser beam uniform are sequentially arranged on the emission side optical path of the excimer laser 71 that emits the pulsed laser beam 72. Has been.

As the attenuator 73 and the homogenizing optical system 74, commonly used optical components for laser can be used. An alignment mark forming mask or shifter 16 or phase shifter 41 is arranged in the outgoing side optical path of the homogenizing optical system 74 so that it can be used interchangeably. The phase modulation type laser crystallization apparatus 70 can perform the second irradiation (usually a plurality of times) by the phase shifter 41 after replacing the first irradiation (usually a plurality of times) by the alignment mark forming mask or the shifter 16. it can.

The replacement mechanism of the alignment mark forming mask or shifter 16 or phase shifter 41 is provided with a moving mechanism 84 which is generally used for replacement of parts such as an exposure apparatus, and the alignment mark forming mask or shifter 16 and the phase shifter. 41 can be exchanged. Further, a projection lens 77 for reducing the laser beam pattern formed by the alignment mark forming mask or shifter 16 or the phase shifter 41 is disposed on the emission side optical path of the alignment mark forming mask or shifter 16 and the phase shifter 41. Yes.

  In the exit side optical path of the projection lens 77, for example, an XYZθ stage 78 (movable in X, Y, Z directions perpendicular to each other and movable at an arbitrary angle θ in the XY plane) is movable with respect to the laser beam. The stage capable of rotating is provided. At a predetermined position of the XYZθ stage 78, the workpiece 10 shown in FIGS. 1A and 1B is arranged. Since the XYZθ stage 78 moves relative to the laser beam, a driving device 81 is provided. Further, a light receiving device 82 for recognizing the position of the alignment mark 15 formed on the workpiece 10 on the XYZθ stage 78 is provided.

  The excimer laser 71, the attenuator 73, the alignment mark formation mask or shifter 16 or the phase shifter 41, and the like, a moving mechanism 84 for selectively exchanging, a driving device 81, and a light receiving device (imaging device) 82 are connected to each signal line 87. Via the control device 83. The control device 83 processes signals from each of the devices 71, 73, 84, 81, 82, and generates a control signal necessary for the devices 71, 73, 84, 81, 82. It has a storage unit 86 for storing information and programs necessary for signal processing.

The control device 83 is a computer having a program that automatically executes the following control, for example. For example, the control device 83 controls the emission of the excimer laser 71 that emits a pulse, controls the energy density of the attenuator 73 in the first irradiation and the second irradiation, and exchanges the mask or shifter using the mask or shifter moving mechanism 84. Various controls necessary for the crystallization apparatus, including control of the movement of the XYZθ stage 78 by the driving device 81, position recognition of the semiconductor thin film 13 by the alignment mark 64 and the light receiving device 82, and the like. The control device 83 takes charge of the control of automatically moving the stage 78 in order to move the workpiece 10 to the formation position of the alignment mark 15 or the formation position of the crystallization region 22. The height of the workpiece 10 in the Z direction is detected using the Z position detection mechanism (the light source 89 and the photodetector 89 ′) in FIG. 3, and the Z direction control of the XYZθ stage 78 can be performed for each shot. desirable.

  The position control of the stage 78 by the control device 83 forms the alignment mark 15 at a predetermined position of the amorphous semiconductor thin film 13 by controlling the first laser irradiation. The alignment mark 15 is detected by a light receiving device (imaging device) 82, and the second laser irradiation for crystallization is controlled by the alignment based on the alignment mark 15, and the crystallization is crystallized into a large grain size. Form a region.

  Next, a phase modulation excimer laser crystallization method for crystallizing the workpiece 10 by the crystallization apparatus 70 shown in FIG. 3 will be specifically described with reference to FIGS. The same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof is omitted. In the phase modulation excimer laser crystallization method of this embodiment, for example, a phase shifter 41 as shown in FIG. FIG. 4A is a partially cutaway sectional view of the phase shifter 41.

The phase shifter 41 is configured such that a stepped portion 44 (phase shift portion) is formed by forming strip-shaped uneven regions 42 and 43 having mutually different thicknesses on a transparent base material, for example, a quartz substrate. is there. FIG. 5 shows a perspective view thereof.

The phase shift portion is a step portion 44 formed at the boundary between the two uneven regions 42 and 43, and has a function of diffracting and interfering the incident excimer laser light 45. In this manner, the phase shifter 41 forms a spatial distribution that periodically changes as indicated by the light intensity distribution 46 in FIG. 4B with respect to the excimer laser light incident with a uniform light intensity. That is, the phase shifter 41 transmits the laser beam indicated by the light intensity distribution 46 as shown in FIG. 4B by phase-modulating the excimer laser light incident with a uniform light intensity distribution.

  The phase shifter 41 shown in this embodiment is configured to have a stepped portion 44 such that the laser beams that have passed through the concavo-convex regions 42 and 43 of the adjacent concavo-convex pattern have opposite phases (180 ° deviation). Yes. In other words, the uneven regions 42 and 43 arranged alternately have a first stripe concave region 42 in which the phase difference of the laser light incident in phase is 180 ° after passing, and a phase after passing is 0 °. And a convex region 43 of the second stripe.

  In this embodiment, the phase shifter 41 is made of a rectangular quartz substrate having a refractive index of 1.508, and the uneven regions 42 and 43 of the first and second stripes each have a width of 25 μm in the horizontal direction. The step Δt between the uneven regions 42 and 43 of the first and second stripes corresponds to the phase difference θ of each emitted laser beam. The phase difference θ is given by θ = 2πΔt (n−1) / λ. Here, λ is the wavelength of the laser beam, and n is the refractive index of the quartz substrate.

For example, when a KrF excimer laser having a wavelength of 248 nm is used, the refractive index is 1.508, and the phase difference of transmitted light is 180 ° when the step Δt is 244 nm. Therefore, the phase shifter 41 can be formed by partially etching a portion corresponding to the concave region 42 of the stripe on the flat quartz substrate by a depth of 244 nm. The region formed thin by this etching is the concave region 42 of the first stripe, and the region not etched is the convex region 43 of the second stripe.

  When the phase shifter 41 having such a configuration is used, a light intensity distribution 46 of the laser light as shown in FIG. 4B is generated. Therefore, in the amorphous semiconductor thin film 13 that has been irradiated with the laser light having such a light intensity distribution 46, the temperature of the portion 55 having the smallest light intensity distribution becomes the lowest, and the amorphous semiconductor thin film 13 is subjected to laser irradiation. A periodic temperature distribution 47 based on the light intensity distribution 46 of light is formed. Normally, an appropriate temperature gradient is formed in the light intensity (fluence) and irradiation time of the laser light so that the semiconductor thin film 13 is melted even in the portion 55 where the light intensity is minimum.

  When it is time to stop the irradiation with the excimer (pulse) laser beam 45, first, the temperature of the semiconductor thin film 13 is equal to or lower than the melting point in the portion 55 where the light intensity is minimum, that is, the portion 49 where temperature is minimum or in the vicinity thereof. Crystallization is started, and microcrystals or polycrystals serving as nuclei are generated when the semiconductor thin film 13 is crystallized. That is, in the lowest temperature portion 48, initially microcrystals or polycrystals are produced. However, while the crystal grows sequentially from the low temperature portion in the temperature gradient portion, the growth of the crystal portion having a crystal orientation particularly suitable for growth expands in the lateral direction.

At this time, due to the heat storage effect of the capping layer 14 and the base film 12 formed on the front and back surfaces of the semiconductor thin film 13, the melted portion of the semiconductor thin film 13 slowly cools down, so that it falls below the freezing point according to the temperature gradient of the temperature ramp 48. Crystallization proceeds sequentially from the temperature-decreasing portion, and the crystallization proceeds sequentially in the lateral direction. For this reason, a plurality of relatively large crystal grains are obtained in each temperature gradient portion 48, and a crystallized region having a large particle size comparable to the size of the active region of the TFT 23 is formed.

  In the above description, as shown in FIG. 4A and FIG. 6, the phase shifter 41 uses the phase shifter 41 in which the phase shift portions including the step portions 44 are formed in a plurality of straight lines. Explained the case. However, the structure of the phase shifter 41 is not limited to this example. For example, as shown in FIG. 6, an area modulation type phase shifter in which stepped portions 44 having different areas are formed in a lattice shape may be used.

That is, the area modulation type phase shifter is obtained by finely changing the area of the convex region 43 of the second stripe as shown in FIGS. 6A and 6B so as to obtain the light intensity distribution 46 of FIG. The mask is obtained by modulating the area ratio. In FIG. 6B, W is the repetition length of the phase shifter 41, and Δt is the step portion 44. In FIG. 6C, 46 is a beam profile (light intensity distribution), PH is the amplitude of the beam profile, PW is the pitch width of the beam profile, and θ is between the inclined portions in the beam profile. Is an angle.

  FIG. 4C is a diagram showing a crystal growth state in association with the phase shift mask 41 shown in FIG. FIG. 4C is a schematic diagram of a micrograph of the amorphous semiconductor thin film 13 crystallized using the phase shifter 41 of the crystallization apparatus shown in FIG. FIG. 4 (c) shows the following crystallization state. In FIG. 4C, each of the crystal portions is made of fine crystals in the vertical direction corresponding to each minimum portion 48 of the temperature distribution 47 generated by irradiating the light transmitted through the phase shift mask 41 to the amorphous semiconductor thin film 13. The state in which the polycrystalline region 51 is formed is shown.

Further, FIG. 4C shows a state in which crystals grow from the polycrystalline region 51 in the lateral direction (in the direction of the arrow 57) and grow into a large single crystal group having a grain length of about 2.5 μm, for example. It is shown. Crystal growth ends at an intermediate portion between the left and right polycrystalline regions 51, and this intermediate portion is a place where crystal growth has occurred from the left and right, and a longitudinal grain boundary 53 is generated. The large crystallization region 52 can obtain a crystallization region having a desired size by appropriately selecting the temperature distribution 47, and the crystallization region having a large grain size adjacent to the polycrystalline region 51. 52 is formed.

  FIG. 4D shows an example of each element formation section 54 corresponding to the crystallized semiconductor thin film 13 shown in FIG. For example, the TFT 23 shown in FIG. 1 or at least the channel region 25 of the TFT 23 is formed in the crystallized region 21 having a large particle size in the element forming section 54. 4A, 4B, 4C, and 4D are illustrated in association with the phase shift portion (stepped portion 44) of the phase shifter 41 in FIG.

  FIG. 8 shows a specific example of a display panel for a display device in which a number of element formation sections 54 shown in FIG. 4D are formed on a support substrate 11 made of a large-area insulator. Fig.8 (a) is a top view of the to-be-processed object 10, (b) A figure is an AA 'cut surface view of (a).

For example, an SiO 2 film, for example, is formed as an insulating film 12 that is an undercoat layer on a support substrate 11 made of an alkali-free glass substrate, and an amorphous semiconductor thin film 13 such as an amorphous silicon film is formed thereon. On the amorphous silicon thin film, a capping layer 14 (not shown) is formed as shown in FIG. An alignment mark 15 is first formed on the amorphous semiconductor thin film 13 by the first laser irradiation.

  Subsequently, a plurality of crystallized regions 22 are formed in the amorphous or polycrystalline semiconductor thin film 13 with the alignment mark 15 as a reference. Each crystallization region 22 is irradiated with a second laser beam on the amorphous semiconductor thin film 13 each time the XYZθ stage 78 on which the insulating substrate 11 is placed is moved at a predetermined interval, for example. A crystallization region is formed.

Since each second laser irradiation can be aligned each time by the alignment mark 15 formed on the amorphous semiconductor thin film 13, the crystallization region 21 can be accurately arranged on the support substrate 11. Each crystallization region 21 includes a plurality of element formation sections 54. The alignment mark 15 can also be used in the manufacturing process of the thin film transistor 23 and the like. Furthermore, the alignment mark 15 can also be used in a cutting process or a substrate bonding process.

  Next, an embodiment in which the method of the present invention is applied to an active matrix liquid crystal display device will be described with reference to FIG. FIG. 9A is a plan view for explaining a connection state of a circuit portion of the liquid crystal display device, and FIG. 9B is a cross-sectional view of the liquid crystal display device. The same parts as those in FIGS. 1 to 8 are denoted by the same reference numerals, and detailed description thereof will be omitted.

  FIGS. 9A and 9B show an embodiment of a liquid crystal display device formed by using a thin film semiconductor including a crystallized region formed on the thin film semiconductor 13 by the method of the present invention. An alignment mark formed for alignment of the TFTs constituting the signal line driving circuit 100 in the upper part of the liquid crystal display device 90 of FIG. 9A is indicated by 15A, and the positions of the TFTs constituting the lower display portion 119 are indicated. An alignment mark formed for alignment is indicated by 15B, and an alignment mark formed for alignment of the TFTs constituting the side scanning line driving circuit 99 is indicated by 15C.

FIG. 9A shows an element formation region corresponding to the element formation section 54 of FIG. For simplification of the drawing, only the upper right part is shown, and the others are omitted. In this embodiment, the alignment marks 15 are arranged at the four corners such as the drive circuit portion and the display portion, but the number and arrangement of the alignment marks 15 can be appropriately determined according to the number and arrangement of the element formation regions.

Next, the workpiece 10 is heated and irradiated by the lamp light from the flash lamp 63 by the annealing apparatus 59 shown in FIG. As a result, the microcrystalline region in which the crystallization region 21 is unevenly distributed is recrystallized and reduced. However, since the capping layer 14 is removed and the heat storage effect due to the capping layer 14 does not exist in the alignment mark 15 and its peripheral region, the temperature does not rise above the region of the crystallized semiconductor thin film 97, and the alignment mark 15 And the crystallinity of the surrounding area are ensured. As a result, the distinguishability between the alignment mark 15 and its periphery is ensured.

  As shown in FIG. 9B, the liquid crystal display device 90 includes a pair of upper and lower transparent substrates 91 and 92, and liquid crystal injected uniformly interposed between the transparent substrates 91 and 92. A layer 93, a plurality of pixel (display) electrodes 94 provided on the inner wall surface of the transparent substrate 92, and a counter electrode 97 are provided on the inner wall surface of the transparent substrate 91. On the inner wall surface of the transparent substrate 92, as shown in FIG. 9A, a plurality of pixel electrodes 94, a plurality of scanning wirings 95, a plurality of signal wirings 96, and the pixel electrodes 94 are arranged in a matrix. A plurality of TFTs 23 connected to each other are provided.

  As the pair of transparent substrates 91 and 92, for example, a glass substrate can be used. These transparent substrates 91 and 92 are joined via a frame-shaped sealing material 118. The liquid crystal layer 93 is disposed in a region surrounded by the pair of transparent substrates 91 and 92 and the sealing material 118.

  On the inner surface of one of the pair of transparent substrates 91, 92, for example, the lower transparent substrate 92, a plurality of pixel electrodes 94 provided in a matrix in the row direction and the column direction, and the plurality of pixel electrodes 94 A plurality of TFTs 98 respectively connected to the pixel electrodes 94, and scanning wirings 95 and signal wirings 96 electrically connected to the plurality of TFTs 98 are provided. In this embodiment, signal line and scanning line driving circuit TFTs 98 and pixel switching TFTs are formed in recrystallized element forming regions 100, 99, and 103, respectively.

  The plurality of scanning wirings 95 extend in the row direction and are connected to the gate electrode of the TFT 98. One end of each of the scanning lines 95 is connected to the scanning line driving circuit 99. The plurality of signal wirings 96 extend in the column direction and are connected to the thin film transistors 98. One end of each of these signal lines 96 is connected to the signal line drive circuit portion 100. The scanning line driving circuit 99 and the signal line driving circuit portion 100 are connected to the liquid crystal controller 101.

  As described above, in the embodiment shown in FIG. 9, the amorphous semiconductor thin film 13 is formed on the transparent substrate, for example, the glass substrate 11 via the base insulating film. On the surface of the amorphous semiconductor thin film 13, a plurality of alignment marks 15 are formed at predetermined positions of the semiconductor thin film 13 by the first laser irradiation.

The alignment mark 15 is optically recognized, and the position to be crystallized by the excimer laser light phase-modulated with the alignment mark 15 as a reference is determined. Then, for example, each circuit including the TFT 23 is formed in each element formation region corresponding to each element formation section 54 shown in FIG. 8 with the alignment mark 15 as a reference. The TFT 23 can be formed using a known TFT manufacturing process.

It is sectional drawing for demonstrating embodiment of this invention method to process order. It is a figure for demonstrating the alignment mark of FIG. It is a system block diagram for demonstrating the crystallization process and crystallization apparatus of FIG. It is explanatory drawing for demonstrating the crystallization process of FIG. It is explanatory drawing of the annealing apparatus for implementing the annealing process by the flash lamp of FIG. It is a perspective view of the phase shifter of FIG. It is a figure for demonstrating embodiment of the other phase shifter of FIG. It is the top view and sectional drawing of the to-be-processed object for demonstrating other embodiment of FIG. It is the top view and sectional drawing for demonstrating embodiment which applied the display apparatus of this invention to the liquid crystal display device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... To-be-processed object, 11 ... Support substrate, 12 ... Insulating film (underlayer film), 13 ... Semiconductor thin film, 14 ... Protective film (capping layer), 15 ... Alignment mark, 16 ... Mask or shifter for alignment formation, 17 ... Mask: 18 ... Transparent substrate, 19A ... Metal thin film, 19B ... Penetration part, L1 ... Laser light, L2, 45 ... Excimer laser light, 21 ... Crystallized region, 22 ... Recrystallized region, 23 ... Thin film transistor (TFT), 24 ... Source region, 25 ... Channel region, 26 ... Drain region, 27 ... Gate insulating film, 28 ... Gate electrode, 29 ... Source electrode, 30 ... Drain electrode, 31 ... Interlayer insulating film, 41 ... Phase shifter, 42, 43 ... Uneven region, 44 ... Step part (phase shift part), 45 ... Excimer laser light, 46 ... Light intensity distribution, 47 ... Degree distribution, 48 ... temperature gradient part, 49 ... minimum part of temperature, 51 ... polycrystalline region, 52 ... crystallization region, 53 ... crystal grain boundary, 54 ... element formation section, 55 ... part with minimum light intensity, 57 ... Arrow, 59 ... Annealing device, 60 ... Vacuum container, 61 ... Exhaust port, 62 ... Stage, 63 ... Flash lamp, 64 ... Lamp chamber, 65 ... Reflector, 68 ... Translucent plate, 70 ... Crystallizer, 71 ... Excimer laser, 72 ... pulse laser beam, 73 ... attenuator, 74 ... homogenizing optical system, 75 ... mask or shifter, 76 ... phase shifter, 77 ... projection lens, 78 ... XYZθ stage, 81 ... drive device, 82 ... light receiving device, 83 ... Control device, 84 ... Mask or shifter moving mechanism, 85 ... Signal processing unit, 86 ... Storage unit, 87 ... Signal line, DESCRIPTION OF SYMBOLS 8 ... Alignment mark detection apparatus, 89, 89 '... Z position detection mechanism, 90 ... Liquid crystal display device, 91 ... Transparent substrate, 92 ... Transparent substrate, 93 ... Liquid crystal layer, 94 ... Pixel (display) electrode, 95 ... Scanning wiring 96 ... Signal wiring, 97 ... Counter electrode, 99 ... Scanning line drive circuit, 100 ... Signal line drive circuit part, 101 ... Liquid crystal controller, 103 ... Pixel switching element formation region, 118 ... Seal material, 119 ... Display part.

Claims (6)

A method for crystallizing a non-single crystal semiconductor thin film,
Forming a capping layer on the non-single-crystal semiconductor thin film;
Forming an alignment mark at a predetermined position of the non-single-crystal semiconductor thin film by irradiating a first laser beam;
A crystallization step of forming a crystallization region by irradiating a second laser beam on a predetermined position of the non-single-crystal semiconductor thin film aligned based on the alignment mark;
Removing the capping layer in a peripheral region including on the alignment mark;
And a step of irradiating a region including the crystallization region with flash lamp light.   The crystallization method according to claim 1, wherein the second laser beam has a larger energy density than the first laser beam.   In the crystallization step, the non-single crystal semiconductor thin film is moved relative to the second laser, and the second laser sequentially scans the non-single crystal semiconductor thin film, and is based on the alignment mark. 2. The crystallization method according to claim 1, wherein the second laser light is irradiated a plurality of times by alignment.   3. The crystallization method according to claim 2, wherein the first laser light and the second laser light are performed by using the same laser light source and changing to a predetermined energy density by an attenuator disposed in an optical path of the laser light. . A thin film transistor, wherein at least a channel region is manufactured based on the alignment mark in the crystallized region crystallized by the method according to claim 1. A display device comprising: a thin film transistor in which at least a channel region is formed with reference to the alignment mark in a region crystallized by the method according to claim 1.

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