JP2011082545A - Heat treatment apparatus, heat treatment method, method of manufacturing semiconductor device and method of manufacturing display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the throughput of formation of a semiconductor element by heat treatment on a semiconductor film using an energy beam. <P>SOLUTION: A semiconductor treatment apparatus is disclosed which includes: a stage 20 on which a substrate 10 having the semiconductor film 11 to be treated is mounted; a supply unit 30 which supplies a plurality of energy beams B on the semiconductor film 11 of the substrate 10 mounted on the stage 20 so that irradiation points of the energy beams are arrayed at constant intervals; and a control unit 40 which causes the plurality of energy beams B and the substrate 10 to relatively move in a direction not parallel with the array of the irradiation points of the plurality of energy beams B supplied through the supply unit 30, and scans the semiconductor film 11 with the irradiation points of the plurality of energy beams B in parallel, thereby controlling the heat treatment of the semiconductor film 11. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a semiconductor processing apparatus and a semiconductor processing method for irradiating a semiconductor film provided on a substrate with an energy beam and performing crystallization by heat treatment.

  In a flat display device such as a liquid crystal display device or an organic EL (Electro Luminescence) display device, a thin film transistor (TFT) is used as a switching element for performing an active matrix display of a plurality of pixels.

  For thin film transistors, polycrystalline silicon (poly-Si) or microcrystalline silicon (μc-Si) is used in the active region (polycrystalline silicon TFT), and amorphous silicon (amorphous Si) is used in the active region. (Non-crystalline silicon TFT). Among these, the polycrystalline silicon TFT has a feature that the carrier mobility is about 10 to 100 times larger than that of the amorphous silicon TFT, and has a very excellent characteristic as a constituent material of the switching element. Yes.

  On the other hand, the conventional liquid crystal driving pixel switching element does not require such a high mobility, and therefore amorphous silicon TFTs are generally used as pixel switches. However, for organic EL and high frame applications, which are expected to be driven by next-generation TFTs, devices having higher mobility than amorphous silicon TFTs are desired.

  However, the characteristics of the polycrystalline silicon TFT are due to the presence of both the crystal region and the grain boundary region in the channel region, which is the heart of the transistor, resulting in device variations such as mobility and threshold voltage. Cheap. There is a trade-off correlation between the mobility and the variation, and it is said that the device variation increases as the mobility increases.

  Many studies have been made on the relationship caused by the grain boundaries peculiar to such polycrystalline silicon TFTs.

  For example, Patent Document 1 discloses a technique for irradiating an excimer laser through a diffraction grating mask in addition to a method for controlling the crystal orientation by repeated irradiation. That is, crystal growth occurs starting from the minimum intensity point modulated by the diffraction grating mask, and the position of the crystal grain boundary is controlled by controlling the position of the crystal grain boundary at the maximum light intensity point.

  On the other hand, in another technique, a method of crystallizing while scanning a laser is disclosed. As an example, a SELAX (Selectively Enlarging Laser Crystallization) method disclosed in Patent Document 2 is disclosed. In this method, a continuous wave (CW) laser or a pseudo CW laser beam having an extremely high pulse frequency of several tens of MHz or more is used, and this is moved (scanned) relative to a silicon film formed on a substrate in one direction. Is.

  By this laser scanning, a crystal grows along one direction. Crystal grain boundaries are formed substantially parallel to the growth direction. Therefore, the electric conduction in the crystal growth direction can increase the mobility because the density of the crystal grain boundaries traversed by the carriers decreases.

  On the other hand, the closer the channel part is to a single crystal, the more in-plane crystal orientation difference, subtle angle difference in surface orientation, and internal defect difference appear more prominently, which reduces device variation. Therefore, it is necessary to form a crystal film equivalent to a high quality single crystal Si substrate.

  Under these circumstances, Patent Document 3 discloses a technique for forming a polycrystal in which the number of crystal grain boundaries where carriers cross the crystal is controlled, instead of making the silicon in the channel a single crystal. According to Patent Document 4, a crystal grain boundary is formed by scanning a spot laser at an equal pitch in a channel region. As a result, it is possible to form a transistor with a relatively high mobility and a small element variation.

JP 2004-87535 A JP 2004-87667 A JP 2007-281422 A JP 2007-281420 A

  However, one of the problems with these methods is that the throughput cannot be increased. That is, in order to crystallize the silicon film in the channel with a beam having a small spot diameter, it is necessary to scan the beam many times, which hinders productivity improvement.

  An object of the present invention is to provide a technique capable of improving throughput in forming a semiconductor element by heat treatment of a semiconductor film using an energy beam.

  The present invention provides a stage on which a substrate including a semiconductor film to be processed is placed, and an energy beam so that irradiation points of a plurality of energy beams are arranged at regular intervals on the semiconductor film of the substrate placed on the stage. A plurality of energy beams and a substrate are moved relative to each other in a direction not parallel to the supply unit to be supplied and the arrangement of irradiation points of the plurality of energy beams supplied by the supply unit. And a control unit that scans in parallel and controls the heat treatment of the semiconductor film.

  In addition, the present invention includes a step of supplying an energy beam so that irradiation points of a plurality of energy beams are arranged at regular intervals on a semiconductor film provided on a substrate to be processed, and irradiation of a plurality of energy beams to be supplied A semiconductor having a step of relatively moving a plurality of energy beams and a substrate in a direction not parallel to the arrangement of the dots, scanning the irradiation points of the plurality of energy beams in parallel on the semiconductor film, and controlling the heat treatment of the semiconductor film It is a processing method.

  In the present invention, since the irradiation points of a plurality of energy beams are arranged at regular intervals and the substrate is scanned in parallel, the area that can be processed simultaneously can be increased as compared with the case of scanning one beam irradiation point. it can.

  According to the present invention, when a semiconductor element is formed by heat treatment of a semiconductor film using an energy beam, the throughput can be improved.

It is a figure explaining the schematic structure of the semiconductor processing apparatus which concerns on this embodiment. It is a block diagram explaining the specific example of the semiconductor processing apparatus which concerns on this embodiment. It is a schematic cross section explaining a diffraction grating. It is a schematic diagram explaining the arrangement direction of the irradiation point of an energy beam. It is a schematic diagram which shows the state of the crystal | crystallization after laser annealing. It is a schematic diagram explaining the beam spot diameter of the laser beam formed with a diffraction grating. It is a figure which shows the profile by the relative radiation intensity of a beam. It is a figure which shows the relationship between the beam energy at the time of heat-processing a semiconductor film in the beam diameter of 1.2 micrometers, and the magnitude | size of a crystal grain. It is a schematic diagram explaining the beam profile of the laser beam formed with a diffraction grating. It is a schematic diagram explaining the angle with the arrangement | sequence of a beam spot and a scanning direction. It is a schematic diagram explaining the dividing method of the laser beam which is an energy beam. It is a schematic diagram explaining the dividing method of the laser beam which is an energy beam. It is a schematic diagram explaining the scanning direction in the irradiation of the laser beam by this embodiment. It is a schematic diagram which shows the state of the crystal grain at the time of a folding scan. It is FIG. (1) explaining the manufacturing method of a thin film semiconductor device. It is FIG. (2) explaining the manufacturing method of a thin film semiconductor device. It is FIG. (3) explaining the manufacturing method of a thin film semiconductor device. It is FIG. (4) explaining the manufacturing method of a thin film semiconductor device. It is FIG. (5) explaining the manufacturing method of a thin film semiconductor device. It is FIG. (6) explaining the manufacturing method of a thin film semiconductor device.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The semiconductor processing apparatus according to the embodiment described here is for crystallizing and activating an amorphous semiconductor film such as silicon or germanium formed on a substrate in a process such as crystallization activation of a semiconductor thin film. The device used.

<Schematic configuration of semiconductor processing apparatus>
FIG. 1 is a diagram illustrating a schematic configuration of a semiconductor processing apparatus according to the present embodiment. The semiconductor processing apparatus according to the present embodiment controls the stage 20 on which the substrate 10 including the semiconductor film 11 to be processed is placed, the supply unit 30 that supplies the energy beam, the stage 20, and the irradiation of the energy beam. A control unit 40 is provided.

  The stage 20 has a function of moving in the vertical and horizontal (XY) directions with the substrate 10 placed thereon. Further, it has a function of moving in the height (Z) direction and a function of moving in the rotation (θ) direction as necessary.

  The supply unit 30 is a part that supplies an energy beam such that the irradiation points of the plurality of energy beams B are arranged at regular intervals on the semiconductor film 11 of the substrate 10 placed on the stage 20. Laser beam is used as the energy beam B. Therefore, the supply unit 30 includes a light source unit that emits laser light, a beam shaping unit that shapes the laser light emitted from the light source, and a dividing unit that divides the laser light into a plurality of energy beams B.

  The control unit 40 controls the movement of the stage 20 in the X and Y directions, as necessary, in the Z direction and the θ direction, and gives an instruction to the supply unit 30 to control the energy amount of the energy beam B. Thereby, the state of the heat treatment for the semiconductor film 10 of the substrate 10 is controlled.

<Specific examples of semiconductor processing equipment>
FIG. 2 is a configuration diagram illustrating a specific example of the semiconductor processing apparatus according to the present embodiment. The semiconductor processing apparatus shown in this figure includes a stage 20 on which a substrate 10 is placed, a light source unit 31 that oscillates laser light, a laser beam synthesis unit, a beam shaping unit 32 that shapes the irradiation shape of the laser beam, and the intensity of the laser beam. A diffraction grating mask irradiating unit 33 serving as a dividing unit that performs division with modulation is provided. Here, the light source unit 31, the beam shaping unit 32, and the diffraction grating mask irradiation unit 33 are provided in the supply unit 30 shown in FIG. 1, and the control unit 40 controls these and the stage 20.

  Among the above-described configurations, the stage 20 is provided with a slider that can keep the substrate 10 placed on the stage 20 horizontal and can move and scan the substrate freely in the XY directions in the horizontal plane. It has become. Here, when the substrate 10 placed on the stage 20 has flexibility and bends flexibly, the stage 20 is provided with a roll-to-roll substrate winding mechanism at an end thereof, and the substrate 10 The substrate 10 may be configured so as to be able to be wound up in one direction (for example, ± Y direction).

  The light source unit 31 is composed of a semiconductor laser oscillator. As the semiconductor laser oscillator, one that oscillates laser light having an appropriate characteristic and wavelength is selected depending on what kind of processing is performed using the semiconductor processing apparatus.

  For example, when this semiconductor processing apparatus is used for crystallization and activation of a semiconductor thin film made of amorphous silicon, the oscillation wavelength includes a wavelength of 350 nm to 470 nm in consideration of the stability of the laser and the absorption coefficient of the semiconductor film. , Ga and N-containing compound semiconductor laser oscillators are used. In addition, a Kr gas laser or the like is preferably used for a semiconductor laser, a solid-state laser, or a gas laser such as a second harmonic of a titanium sapphire laser, a second harmonic of an Nd: YVO4, or an Nd: YAG laser.

  Further, the beam shaping unit 32 cuts out each region of the laser light having a profile close to the Gaussian shape oscillated from the light source unit 31 with a cylindrical or honeycomb lens, and superimposes them to form a predetermined top hat type beam shape. Is possible.

  Specifically, a mirror that reflects the laser light emitted from the light source unit 31, a lens that collimates the laser light reflected by the mirror, a homogenizer and a lens that mold the parallel light into a top hat shape, and a top hat And a mirror for guiding the laser beam of the mold to the diffraction grating of the diffraction grating mask irradiation unit 33.

  These optical systems (also referred to as optical heads) are configured in a compact manner, and are formed on a linear drive type slider so that the optical system can be moved at high speed and constant speed in one axial direction on the substrate 10 as required. May be. In this case, it is desirable to reduce the load and size of the optical head part by designing the optical head part to be introduced before the beam combining part except when a small semiconductor laser is used.

  The laser beam shaped into a top hat beam shape by the beam shaping unit 32 is modulated by the diffraction grating of the diffraction grating mask irradiation unit 33, and becomes an energy beam in which a plurality of irradiation points are arranged at regular intervals.

  FIG. 3 is a schematic cross-sectional view illustrating a diffraction grating. The diffraction grating has linear irregularities arranged on one side of a glass substrate at a predetermined pitch (grating pitch), and modulates the intensity of incident semiconductor laser light by interference fringes. In the present embodiment, the grating pitch a is, for example, 0.4 to 2.0 μm, and the interference pitch d is a / 2.

  A top-hat type laser beam is modulated using such a diffraction grating, and an array of irradiation points (beam spots) of a large number of beams according to the interference pitch is formed. In the semiconductor processing apparatus of this embodiment, the multiple beam spots are irradiated on the substrate in parallel.

  Here, when the optical head side is fixed and used, the stage 20 is configured to move in a direction not parallel to the pitch direction of the diffraction grating. As a result, the maximum intensity point (beam spot) modulated by the diffraction grating can be set to cross the channel portion of the semiconductor device designed on the substrate 10 placed on the stage 20.

  In other words, in such a configuration, the laser beam is scanned in one direction (for example, the X direction) while being imaged while having an intensity distribution on the substrate 10.

  Further, by specifying and irradiating a plurality of beam spots on the channel region on the substrate 10, the overall processing speed can be increased. For this reason, it is desirable that there is an observation unit that can observe the alignment mark provided at a predetermined position on the substrate 10. The observation unit may be in a different part from the optical head as long as the positional relationship with the optical head is maintained.

  The observation unit is a part for monitoring the alignment mark that is the same reference point written in advance on the substrate surface. This observation unit is an illumination light source that irradiates illumination light, and shaping of illumination light emitted from the illumination light source. A shaping unit, an imaging unit that receives the illumination light shaped by the shaping unit, and a monitor for projecting an image detected by the imaging unit.

  Here, the processing units including the stage 20 and the supply unit 30 may be provided in an increased number within a range in which adjustment between the units is possible. By performing parallel processing of the arranged processing units, the throughput is further improved.

<Semiconductor processing method>
In order to manufacture a semiconductor device such as a thin film transistor using the semiconductor processing apparatus having the above-described configuration, the following procedure is performed. First, laser light that is an energy beam is generated by the light source unit 31 of the supply unit 30, and the substrate is irradiated with laser light in which a plurality of irradiation points are arranged at regular intervals via the beam shaping unit 32 and the diffraction grating mask irradiation unit 33. To do.

  In this state, in order to scan the laser beam at a plurality of irradiation points in the X direction on the substrate, relative movement is performed by driving the stage 20 or the optical head. As a result, a laser beam in which a plurality of irradiation points are arranged at regular intervals can be scanned in parallel on the semiconductor film 11 of the substrate 10.

  Thereafter, the laser irradiation is repeatedly performed in the X direction while moving the substrate 10 on the stage 20 in the Y direction. Thereby, the process which irradiated the laser beam with respect to the XY two-dimensional arbitrary positions on the board | substrate 10 can be performed.

  According to this semiconductor processing apparatus, the laser beam is scanned relatively with respect to the substrate 10 placed on the stage 20, and this allows the substrate 10 to be scanned at a high speed exceeding 0.1 m / second, for example. The substrate 10 can be continuously irradiated with laser light by scanning with laser light. And the annealing process of reducing the thermal load with respect to the board | substrate 10 with the moving speed and energy amount of the laser beam with respect to the board | substrate 10 can also be performed.

  As a result, it is possible to perform an annealing process in which the thermal load on the substrate 10 is reduced by adjusting the moving speed of the laser light at high speed or reducing the amount of energy. For example, in an annealing process for crystallizing a semiconductor thin film on the substrate 10, it is possible to use a plastic substrate having lower heat resistance. Thereby, for example, in the manufacturing process of the thin film semiconductor device, it is possible to realize a mass production process that suppresses the equipment cost of roll-to-roll using a substrate having flexibility.

  Further, on the substrate 10 to be irradiated with laser light, there are cases where an electrode pattern or the like is patterned in advance or the substrate itself is considerably wavy. Therefore, when there is no mechanism for always optimizing the focus of the laser beam, it is necessary to irradiate with a laser having a considerable focus depth. When using a highly focused laser objective lens, the irradiation area is monitored in advance with an element with a focus servo function, and when the laser beam for annealing comes to the pre-read area, it reaches the optimum focus position. It can also be controlled.

<Arrangement direction of energy beam irradiation points>
FIG. 4 is a schematic diagram for explaining the direction of alignment of irradiation points of energy beams. In this embodiment, when the substrate is irradiated with an energy beam in which a plurality of irradiation points are arranged at regular intervals, the direction in which the plurality of irradiation points are arranged is inclined with respect to the scanning direction. In the example shown in FIG. 4, a region surrounded by a square frame in the drawing is a laser beam irradiation region by a plurality of irradiation points, and an arrow in the drawing indicates a scanning direction. As described above, the direction in which the plurality of irradiation points are arranged is inclined with respect to the scanning direction, so that there is a time difference in the timing when the beam spot hits for the row of scans at each irradiation point. Crystal grains can be formed accurately.

  Here, the crystal grains are formed as follows. That is, when a laser beam irradiation point (beam spot) is irradiated onto a semiconductor film, a part or the whole of the semiconductor film is completely melted by thermal energy. Therefore, when scanning with the beam spot, in the scanning path in which the semiconductor film is completely melted, solidification progresses as the laser beam passes, and crystal grains are arranged along the scanning center of the laser beam.

  At this time, by setting the beam profile of the laser beam to, for example, a Gaussian shape profile having a distribution with a high central portion and a low peripheral portion, the temperature of the irradiated portion of the laser beam is set to the beam profile of the laser beam. Corresponding to the Gaussian profile of the laser beam, it is highest at the scanning center of the laser beam and lowest at both ends. Therefore, by irradiating the laser beam while scanning in the scanning direction, in the scanning path where the semiconductor film is completely melted, crystal solidification is started from a position far from the scanning center (both ends of the laser beam scanning path), A certain number of crystal seeds are generated at both ends of the scanning path.

  Further, by further scanning the laser beam, solidification proceeds in the scanning direction toward the scanning center side, and solidification proceeds in a state where the crystal seed is pulled toward the scanning center side in the scanning direction. Finally it is crystallized.

  At this time, the scanning speed and output of the laser beam may be further adjusted within the range of the irradiation conditions described above so that coagulation is associated at the scanning center. As a result, crystal grains having a half crescent shape spreading from the scanning center toward both sides of the scanning path, that is, a shape obtained by dividing the crescent moon into two lines with line symmetry are obtained.

  In the present embodiment, since a plurality of irradiation points arranged at regular intervals are scanned in parallel, the melting and solidification are continuously performed with a time difference for each scanning path of adjacent irradiation points by inclining the direction of the alignment with respect to the scanning direction. As a result, the crescent-shaped crystal grains are formed.

  FIG. 5 is a schematic diagram showing the state of the crystal after laser annealing. In this embodiment, the laser beam is interfered by the diffraction grating and intensity modulation is performed to form a plurality of irradiation points. Therefore, a crystal corresponding to the number n of interference points corresponding to the positions of the interference points (beam spots). A grain boundary a is formed. Also, crescent-shaped crystal grains b are formed between adjacent interference points, that is, between crystal grain boundaries a.

  Therefore, in the case of forming a thin film transistor, the interval between a plurality of irradiation points, the scanning speed, and the amount of energy are controlled so that the crystal grain boundaries a are periodically provided in the channel length direction in the semiconductor film region serving as the channel portion of the thin film transistor. . Thereby, a plurality of crystal grain boundaries a are formed in the channel portion, and the characteristics of the thin film transistor can be made uniform within a range in which carrier mobility can be maintained. Specifically, it may be set so that several tens (for example, about 50) crystal grain boundaries a are periodically provided in the channel length direction.

<About beam spots>
Here, the beam spot of the laser beam emphasized by the diffraction grating will be described. FIG. 6 is a schematic diagram for explaining the beam spot diameter of the laser light formed by the diffraction grating. Here, Δx is the width of the laser light incident on the diffraction grating, λ is the wavelength of the laser light, and d is the pitch of the diffraction grating. In this case, the distance g for the laser beam to converge by the diffraction grating is:
g = {√ (d ² −λ ² ) / 2λ} · Δx
Indicated by.

In addition, when the angle at which the laser beam perpendicularly incident on the diffraction grating is diffracted and emitted is θ, the pitch P of the interference fringes that is highlighted by the diffraction grating is
P = λ / 2sin θ = λ / 2 (λ / d) = d / 2
Indicated by.

The beam spot of the laser beam formed by the diffraction grating has a profile that approximates a Gaussian shape. FIG. 7 is a diagram showing a profile according to the relative radiation intensity of the beam. In general, in a beam spot in which the profile of the relative radiation intensity is approximated to a Gaussian shape, the diameter at the position where the peak value of the relative radiation intensity is 1 / e ² (e is the base of natural logarithm), that is, 13.5%. Is defined as the beam diameter φ.

  FIG. 8 is a diagram showing the relationship between the beam energy and the crystal grain size when the semiconductor film is heat-treated at a beam diameter φ of 1.2 μm as defined above. As can be seen from this figure, the size of crystal grains formed by heat treatment of the semiconductor film by laser light irradiation is almost equal to or smaller than the beam diameter. In the present embodiment, by utilizing such properties, for example, the distance between the diffraction grating and the substrate and the amount of energy are set so that the beam spots in a plurality of laser beams have a Gaussian shape, and the size of the formed crystal grains is set. It is precisely controlled.

  FIG. 9 is a schematic diagram illustrating a beam profile of laser light formed by a diffraction grating. As shown in FIG. 9A, the pitch of the plurality of laser beams formed by the diffraction grating is d / 2, where d is the pitch of the diffraction grating.

  Further, depending on the distance between the diffraction grating and the substrate described above, the beam profile of each laser beam becomes a profile approximated to a Gaussian shape. In the present embodiment, as shown in FIG. 9B, the cross section of any rotation angle about the axis passing through the peak value of the relative radiation intensity is used as the Gaussian as the beam profile of the plurality of laser beams formed by the diffraction grating. A beam having a profile approximate to the shape is formed.

  That is, in the present embodiment, when the substrate is irradiated with laser light in which a plurality of irradiation points (beam spots) are arranged at regular intervals, the alignment direction of the beam spots is inclined with respect to the scanning direction. At this time, since each beam spot travels on the scanning path along the scanning direction, the energy distribution on the scanning path is equivalent to the cross-sectional shape of the beam profile along the direction perpendicular to the scanning direction.

  Therefore, by setting the beam to a profile that approximates a Gaussian shape at any rotation angle centered on the axis that penetrates the peak value of the beam profile, a predetermined angle between the alignment of the beam spots and the scan direction Even if a beam is attached, it is possible to obtain a beam profile composed of a profile that is always approximated to a constant Gaussian shape on the scanning path. That is, the peak position of the beam profile on the scanning path becomes a straight line along the scanning path, and the distribution of thermal energy can be made constant on the scanning path.

  Further, as shown in FIG. 9 (c), when scanning and irradiating laser beams in which beam spots are arranged at regular intervals, two adjacent two spots are prevented so as not to generate a gap where the laser beams are not irradiated. Assume a tangent S where the beam spots touch each other on the left and right. Then, the angle θ between the arrangement of the beam spots and the scanning direction (tangent S) is set so that the tangent S is the scanning direction.

  FIG. 10 is a schematic diagram for explaining the angle between the arrangement of beam spots and the scanning direction. Assuming the tangent S that touches two adjacent beam spots on the left and right as described above, and the direction of the tangent S is the scan direction, the direction of the arrangement of the beam spots is inclined by θ with respect to the scan direction. become.

  Thereby, the scanning path by each beam spot does not generate a gap where the beam does not hit, and the entire region to which the laser beam is irradiated is irradiated with the laser beam and can be subjected to heat treatment. By tilting, a time difference is generated at the irradiation position along the scanning direction of each beam spot, and this makes it possible to form crescent-shaped crystal grains b and crystal grain boundaries a.

<Division method of energy beam>
FIGS. 11 to 12 are schematic diagrams for explaining a method of dividing a laser beam that is an energy beam. As described above, the example of using one diffraction grating has been shown as a method of dividing the laser beam so as to have irradiation points having a constant interval. However, the laser beam can be divided by other methods.

  In the example shown in FIG. 11A, two diffraction gratings are overlapped and multiple interference is used. In the example shown in FIG. 11B, laser light is split into two optical paths by a half mirror, and interference is caused by light beams in the two optical paths.

  In the example shown in FIG. 12A, a plurality of optical fibers are linearly arranged, laser light is incident on each optical fiber, and laser light is emitted from the end face of each optical fiber. . Thereby, the interval between the beam spots can be set according to the pitch of each optical fiber. Further, the example shown in FIG. 12B uses a multi-emission laser. A multi-emission laser is a laser element in which a plurality of light emitting points are formed on one substrate. Thereby, laser light is emitted from multiple points according to the pitch at the time of manufacture, and this is irradiated onto the substrate.

  In any example, the laser light and the substrate are relatively moved in a direction not parallel to the arrangement of the plurality of laser light irradiation points. Further, in the case where a predetermined angle is provided between the arrangement of the plurality of irradiation points and the scanning direction, it may be dealt with by rotating the stage on which the optical unit provided with the above-mentioned dividing means or the substrate is placed. .

<About throughput improvement>
FIG. 13 is a schematic diagram for explaining a scanning direction in laser light irradiation according to the present embodiment. When one scanning path row N is formed by arranging a plurality of laser beams, in the present embodiment, scanning is first performed in the order of arrows A1, A2, A3, A4, and A5.

  Next, when scanning the next row, scanning is performed in the order of arrows B1, B2, B3, B4, and B5 which are turned back from the arrow A5 and are in the opposite directions. Further, when scanning the next row, scanning is performed in the order of arrows C1, C2, C3, C4, and C5 which are turned back from the arrow B5 and are in the opposite directions.

  As described above, when the scanning of the column is completed, the next column is folded and sequentially scanned in the opposite direction. As a result, it is not necessary to return to the same position for each scanning column, the moving distance of the optical head or stage can be minimized, and the scanning throughput can be improved.

  FIG. 14 is a schematic diagram showing the state of crystal grains when the scan is turned back. With respect to one scan of the scanning path array N, since the scan directions are opposite in the arrow A direction and the arrow B direction, the crescent-shaped crystal grain directions are opposite. In addition, since the scan direction is opposite between the arrow B direction and the arrow C direction, the crescent-shaped crystal grain directions are opposite. Thus, the crescent-shaped directions of crystal grains are alternately opposite depending on the scanning direction.

<Method for Manufacturing Thin Film Semiconductor Device>
Next, a manufacturing method of a thin film semiconductor device performed following the above crystallization method will be described. Here, a method for manufacturing a semiconductor device in which a plurality of thin film transistors TFT are provided over the same substrate will be described. In the drawing, only one thin film transistor forming portion is mainly shown.

  First, as shown in FIG. 15A, the entire surface of each active region 3a set in the semiconductor thin film 3 on the substrate 1 is selectively crystallized by the crystallization method described above. Then, a band-like crystal grain b is formed in each active region 3a so as to cross the active region 3a. As a result, the crystal grain boundaries a periodically arranged with a width W1 (= several hundred nm) are arranged in a state of crossing the active region 3a. At this time, the length of the band-like crystal grain b is set to about several μm to several hundred μm in accordance with the standard of the thin film transistor.

  Next, as shown in FIG. 15B, the semiconductor thin film 3 is pattern-etched into a predetermined shape so as to leave the crystallized active region 3a, and each active region 3a is divided into islands of a predetermined shape. To separate.

  In this case, as shown in the figure, the semiconductor thin film 3 may be subjected to pattern etching so that the portion of the semiconductor thin film 3 that is not crystallized does not remain around the active region 3a. Further, the semiconductor thin film 3 may be subjected to pattern etching so that a portion of the semiconductor thin film 3 that is not crystallized remains around the active region 3a. In this case, the entire crystallized region in the island-patterned region becomes the active region, and the non-crystalline region left around the region becomes the isolation region.

  Such pattern etching of the semiconductor thin film 3 may be performed before the above-described crystallization step. In this case, the above-described crystallization process is performed on each semiconductor thin film 3 patterned into an island shape including a region to be the active region 3a.

  Next, a gate insulating film (not shown) is formed on the substrate 1 so as to cover the patterned active region 3a. This gate insulating film may be made of silicon oxide or silicon nitride, and can be formed by a known method using ordinary PE-CVD (Plasma-Enhanced Chemical Vapor Deposition). Alternatively, a known SOG (Spin on Glass) film may be formed. The gate insulating film may be formed before the semiconductor thin film 3 is subjected to pattern etching.

  Next, as shown in FIG. 16, a gate electrode 5 having a shape crossing the central portion of each active region 3a divided into island shapes is formed on the gate insulating film. Here, it is important to form the gate electrode 5 along the extending direction of the crystal grain boundaries a (the extending direction of the band-like crystal grains b). An enlarged view of part A in FIG. 3 is shown in FIG.

  As shown in these drawings, the gate electrode 5 is provided so as to cross a portion designed to have a predetermined width W in the active region 3a, and the width of the active region 3a in the portion crossed by the gate electrode 5 is the channel width. W. That is, the crystal grain boundary a is provided in a state of crossing the channel portion C below the gate electrode 5 in the channel width W direction.

  Further, the line width of the gate electrode 5 (ie, corresponding to the channel length L) is designed based on the standard of the thin film transistor formed here, and below that, a predetermined number of crystal grain boundaries a channel the channel portion C. It is assumed that they are set so as to cross the width W direction. If the thin film transistors have the same characteristics, it is important that the channel portion C is provided with substantially the same number of crystal grain boundaries a. Here, the substantially the same number is preferably within a range of ± 1 with respect to the predetermined number.

  As the number of crystal grain boundaries a provided in the channel portion C is smaller, the characteristic variation of the thin film transistor can be made uniform as the variation in the ratio of the actual number to the predetermined number is smaller. For this reason, the number of crystal grain boundaries a provided in the channel portion C is preferably two or more.

  Specifically, as will be described later in the embodiment, the channel portion C has crystal grains in accordance with the channel length L so that about 25 crystal grain boundaries a extending in the channel width W direction are provided. It is preferable to set the width W1 of the grains b (that is, the pitch of the grain boundaries).

  However, as the number of crystal grain boundaries a crossing the channel length L direction in the channel portion C increases, the carrier mobility in the channel length L direction decreases, so the number of crystal grain boundaries a within a range in which the carrier mobility is kept high to some extent. The more the better.

  As described above, it is important to form the gate electrode 5 in a predetermined state with respect to the crystal grain boundary a provided in each active region 3a. For this reason, in the previous crystallization step, as shown in FIG. 18, the scanning direction of the laser beam in each active region 3a is set in accordance with the wiring direction of the gate electrode 5, and the band-like crystal grains b and the crystals thereof are formed. The extending direction of the grain boundaries a is made to coincide with the wiring direction of the gate electrode 5.

  When forming the gate electrode 5 described above, first, an electrode material layer made of, for example, aluminum is formed by sputtering or vapor deposition, and then a resist pattern is formed on the electrode material layer by lithography. Thereafter, the gate electrode 5 is patterned by etching the electrode material layer using this resist pattern as a mask.

  The formation of the gate electrode 5 is not limited to such a procedure, and for example, a method of applying metal fine particles and printing may be used. In the etching of the electrode material layer when forming the gate electrode 5, the gate insulating film may be continuously etched.

  Next, as shown in the cross-sectional view of FIG. 19, the source / drain 7 in which impurities are introduced in a self-aligned manner into the active region 3a is formed by ion implantation using the gate electrode 5 as a mask and subsequent annealing treatment. To do. FIG. 19 corresponds to a cross section in the X-X ′ direction in FIG. 16.

  As a result, a channel portion C is formed below the gate electrode 5, which is a portion where no impurity is introduced in the crystallized active region 3a. Since the channel portion C below the source / drain 7 and the gate electrode 5 is made of polycrystalline silicon obtained by crystallizing the semiconductor thin film 3, the top gate type thin film transistor TFT using the polycrystalline silicon thin film as described above. A thin film semiconductor device 10 in which a plurality of (ie, polycrystalline silicon TFTs) are provided on the same substrate 1 is obtained.

  When a liquid crystal display device is manufactured as a display device using such a thin film transistor TFT as a switching element, the following steps are further performed.

  First, as shown in FIG. 20A, an interlayer insulating film 210 is formed on the substrate 1 of the thin film semiconductor device 100 so as to cover the thin film transistor TFT. Next, a connection hole 210 a reaching the source / drain 7 of the thin film transistor TFT is formed in the interlayer insulating film 210. Then, a wiring 230 connected to the source / drain 7 through the connection hole 210 a is formed on the interlayer insulating film 210.

  Next, a planarization insulating film 250 is formed so as to cover the wiring 230, and a connection hole 250 a reaching the wiring 230 is formed in the planarization insulating film 250. Next, the pixel electrode 270 connected to the source / drain 7 through the connection hole 250 a and the wiring 230 is formed on the planarization insulating film 250. The pixel electrode 270 is formed as a transparent electrode or a reflective electrode depending on the display type of the liquid crystal display device. The drawing shows a cross section of the main part of one pixel.

  Thereafter, although not shown here, an alignment film covering the pixel electrode 270 is formed on the planarization insulating film, and the driving substrate 290 is completed.

  On the other hand, as shown in FIG. 20B, a counter substrate 310 to be disposed to face the drive substrate 290 is prepared. The counter substrate 310 is formed by providing the common electrode 35 on the transparent substrate 330 and further covering the common electrode 350 with an alignment film not shown here. The common electrode 35 is made of a transparent electrode.

  Then, the driving substrate 290 and the counter substrate 310 are disposed to face each other with the spacer 370 in a state where the pixel electrode 270 and the common electrode 350 face each other. Then, the liquid crystal phase LC is filled and sealed between the substrates 290 and 310 maintained at a predetermined interval by the spacer 370, and the liquid crystal display device 410 is completed.

  Note that when an organic EL display device is manufactured using the driving substrate 290 having the above structure, a pixel electrode provided on the driving substrate 290 is an anode (or a cathode), and a hole injection layer and a light emitting layer are formed on the pixel electrode. An organic layer having necessary functions such as a layer and an electron transport layer is laminated, and a common electrode is formed as a cathode (or an anode) on the organic layer.

  In the thin film semiconductor device 100 obtained by using the crystallization method of the present embodiment described above, referring to FIG. 16 and FIG. 17, the crystal grain boundary a extending along the gate electrode 5 has a channel portion C. And periodically arranged in the channel length L direction. As a result, the carrier passing through the channel portion C always moves across the crystal grain boundary a arranged with the predetermined width W1.

  Therefore, by controlling the width (that is, the width W1 of the band-like crystal grain b), the transistor characteristics (carrier mobility) of the thin film transistor TFT in the thin film semiconductor device 1 can be controlled with high accuracy. That is, by making the width W1 of the band-like crystal grains b and the number of the band-like crystal grains b arranged in the channel portion C (that is, the number of crystal grain boundaries a) coincide, Is suppressed.

  In addition, the crystal state between the crystal grain boundaries aa is composed of the same crystal grain b. For this reason, the deterioration of element characteristics is suppressed without including an amorphous region, and the carrier mobility in the channel length L direction is maintained high.

  Therefore, by using each thin film transistor TFT formed in such a thin film semiconductor device as a switching element of a pixel, it is possible to prevent luminance unevenness and color unevenness in the display portion.

  In the above-described embodiment, the method for manufacturing the thin film semiconductor device including the thin film transistor by applying the semiconductor processing method of the present invention has been described. However, the semiconductor processing method of the present invention is not limited to application to a thin film transistor manufacturing method, and can be applied to other electronic device manufacturing methods. In any case, an electronic element with good characteristic accuracy can be obtained by setting the current to flow in a direction crossing the crystal grain boundary a.

  Furthermore, the materials, raw materials, processes, and numerical values exemplified in the above embodiments are merely examples, and different materials, raw materials, processes, and numerical values may be used as necessary.

  DESCRIPTION OF SYMBOLS 10 ... Substrate, 11 ... Semiconductor film, 20 ... Stage, 30 ... Supply part, 40 ... Control part, 31 ... Light source part, 32 ... Beam shaping part, 33 ... Diffraction grating mask irradiation part

Claims (20)

A stage on which a substrate including a semiconductor film to be processed is placed;
A supply unit for supplying an energy beam such that a plurality of energy beam spots are arranged at regular intervals along the first direction on a semiconductor film of a substrate placed on a stage;
A controller that relatively moves the plurality of energy beam spots and the substrate along a second direction different from the first direction;
And
There is a gap between adjacent energy beam spots,
A heat treatment apparatus in which an angle formed by the first direction and the second direction is an acute angle.   The heat treatment apparatus according to claim 1, wherein a plurality of grain boundaries extending along the second direction are formed.   When the interval between two adjacent energy beam spots is d and the angle between the first direction and the second direction is θ, the interval between the two adjacent grain boundaries is d · sin (θ). Item 3. The heat treatment apparatus according to Item 2.   The heat treatment apparatus according to claim 2 or 3, wherein crystal grains having a crescent shape arranged in the second direction are arranged between crystal grain boundaries.   5. The heat treatment apparatus according to claim 1, wherein the semiconductor film is melted and solidified in a third direction perpendicular to the second direction with a time difference corresponding to the speed of relative movement. 6. .   The heat treatment apparatus according to any one of claims 1 to 5, wherein the second direction is a direction of a common inscribed line of two adjacent energy beam spots.   The heat treatment apparatus according to any one of claims 1 to 6, wherein the energy beam spot has a beam profile having a high central portion and a low peripheral portion.   The heat treatment apparatus according to any one of claims 1 to 7, wherein the energy beam is laser light having a wavelength of 350 nm to 470 nm.   The heat treatment apparatus according to any one of claims 1 to 8, wherein the energy beam is laser light oscillated from a semiconductor laser oscillator of a GaN-based compound.   The heat treatment according to any one of claims 1 to 9, wherein the supply unit includes a light source unit that emits an energy beam, and a diffraction grating that divides the energy beam emitted from the light source unit into a plurality of energy beams. apparatus.   The supply unit includes a light source unit that emits an energy beam and a plurality of optical fibers arranged in a straight line. The energy beam emitted from the light source unit is incident on each incident end of the plurality of optical fibers, and The heat treatment apparatus according to any one of claims 1 to 9, wherein an energy beam is emitted from each emission end. A plurality of energy beam spots are arranged on the semiconductor film along the first direction at regular intervals while supplying the energy beam onto the semiconductor film, and a plurality of energy beam spots are arranged along a second direction different from the first direction. A heat treatment method for heat-treating a semiconductor film by relatively moving an energy beam spot and a semiconductor film,
Create a gap between adjacent energy beam spots,
A heat treatment method in which an angle formed by the first direction and the second direction is an acute angle. While supplying an energy beam onto the semiconductor film region so that a plurality of energy beam spots are arranged along the first direction at regular intervals on the semiconductor film region to be a channel portion of the semiconductor device, the first direction A semiconductor device manufacturing method for crystallizing a semiconductor film by relatively moving a plurality of energy beam spots and a semiconductor film along a second direction different from
Create a gap between adjacent energy beam spots,
A method for manufacturing a semiconductor device, wherein an angle formed by a first direction and a second direction is an acute angle.   14. The method of manufacturing a semiconductor device according to claim 13, wherein the gate electrode extending along the second direction is formed corresponding to the crystallized region of the semiconductor film.   The method of manufacturing a semiconductor device according to claim 14, wherein a gate electrode is formed above the crystallized region of the semiconductor film.   The method for manufacturing a semiconductor device according to claim 13, wherein a plurality of crystal grain boundaries extending along the second direction are formed.   The method for manufacturing a semiconductor device according to claim 15, wherein the channel length is a third direction perpendicular to the second direction.   The interval between the plurality of energy beam spots, the angle formed by the first direction and the second direction, the speed of relative movement, and the energy amount of the energy beam spot are set so that the crystal grain boundaries are provided periodically. 18. A method for manufacturing a semiconductor device according to item 17.   19. The method of manufacturing a semiconductor device according to claim 13, wherein the second direction is folded back in a direction opposite to each step of the region irradiated with the energy beam spot. A method of manufacturing a display device having a thin film transistor as a switching element of a pixel,
The energy beam is supplied onto the semiconductor film region so that a plurality of energy beam spots are arranged along the first direction at regular intervals on the region of the semiconductor film that becomes the channel portion of the thin film transistor. A step of crystallizing the semiconductor film by relatively moving the plurality of energy beam spots and the semiconductor film along different second directions;
Create a gap between adjacent energy beam spots,
A method for manufacturing a display device, wherein an angle formed by a first direction and a second direction is an acute angle.

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