JP2007141945A - Display device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent aggregation for blocking the formation of a strip of crystal when forming a strip of crystal silicon film on a substrate by lateral growth. <P>SOLUTION: A recessed defect DF on the substrate is buried for improving a surface state by providing a coating type substrate film SPL on the substrate SUB 1 for forming a silicon film, and a polysilicon film PSI is formed as a precursor film on the substrate film SPL. Continuous oscillation laser beams LL are applied to the polysilicon film PSI and scanning is made in the direction of an arrow S for annealing, thus preventing the occurrence of aggregation caused by the state on the substrate surface in the growth in the scanning direction of the strip of crystal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a display device manufacturing method and a display device manufactured by this manufacturing method, and more particularly, a thin film transistor or the like is formed on a high-quality semiconductor thin film obtained by crystallizing a semiconductor thin film formed on an insulating substrate by irradiating laser light. It is suitable for improving the yield when manufacturing.

  An active matrix type display device using an active element such as a thin film transistor (or an active matrix type image display device or simply a display device) is widely used as a drive element for pixels arranged in a matrix. Yes. Many image display devices of this type have a high quality by disposing a large number of pixel circuits and drive circuits composed of active elements such as thin film transistors (TFTs) formed using a silicon film as a semiconductor film on an insulating substrate. Images can be displayed. Here, a thin film transistor which is a typical example of the active element will be described as an example.

  In a thin film transistor using an amorphous silicon semiconductor film (amorphous silicon semiconductor film) that has been generally used as a semiconductor film, there is a limit to the performance of the thin film transistor represented by its carrier (electron or hole) mobility. Therefore, it has been difficult to construct a circuit that requires high speed and high functionality. In order to realize a high mobility thin film transistor necessary for providing superior image quality, an amorphous silicon film (amorphous silicon film) or a polysilicon film (polycrystalline silicon film) is irradiated with a continuous wave laser. It is effective to form a thin film transistor using the modified silicon film by performing laser annealing for scanning to modify the crystal into a band-like crystal silicon film in which the crystal is laterally grown.

  FIG. 12 is an explanatory diagram of a method for modifying a silicon film to band-like crystallization using continuous wave laser light irradiation. 12A shows a structure of an insulating substrate on which a semiconductor layer to be irradiated is formed, and FIG. 12B shows a state modified by laser light irradiation. A glass or plastic substrate is used as one insulating substrate (SUB1), which is also referred to as a thin film transistor substrate on which a thin film transistor is formed. Usually, the other insulating substrate (SUB2) on which the color filter is formed is also referred to as a color filter substrate. Hereinafter, the insulating substrate may be simply referred to as a substrate.

In FIG. 12, an amorphous silicon film or a polysilicon film (here, described as a polysilicon film PSI) deposited on the insulating substrate SUB1 via a base film SPL (usually a laminated film of SiN and SiO ₂ ) is linear. The amorphous silicon film PSI is irradiated with a continuous oscillation laser beam LL and annealed by scanning that relatively moves the irradiation position along one direction (X direction) as indicated by an arrow, thereby forming the amorphous silicon film PSI into a silicon film SPSI of a band-like crystal. To reform.

  FIG. 13 is a schematic diagram showing a crystal structure of a band-shaped crystal silicon film obtained by irradiation with continuous wave laser light and an example of electrode arrangement of a thin film transistor formed in this sheet film. In the band-like crystal silicon film SPSI, the grain boundaries CB existing between the single crystals of the substantially band-like crystal silicon film exist so as to be substantially in the same direction as the crystal growth direction (lateral direction) CGR. A source electrode SD1 and a drain electrode SD2 are formed at positions facing the crystal growth direction CGR, respectively. The gate electrode GT is indicated by a virtual line. The silicon film SPSI thus modified is subjected to various processes such as etching, wiring formation, and ion implantation to form a circuit having a thin film transistor in each pixel portion or driving portion.

  The source electrode SD1 and the drain electrode SD2 are set so that the direction of the current (channel current) Ich flowing between the two electrodes is substantially parallel to the crystal growth direction CGR. Thus, by making the crystal growth direction CGR and the direction of the current Ich the same, the mobility of electrons in the channel can be increased, and a high-speed thin film transistor can be configured.

Using this insulating substrate SUB1, an active matrix type display device such as a liquid crystal display device or an organic EL display device is manufactured. In the modification of a silicon film using a conventional excimer laser, a large number of crystallized silicon particles (polysilicon) of about 0.05 μm to 0.5 μm grow randomly in the laser light irradiation portion. The field effect mobility of a TFT made of such a polysilicon film is about 300 cm ² / V · s or more. Patent Literature 1, Patent Literature 2, and the like can be cited as methods for obtaining such a high-quality semiconductor thin film.

JP 2003-86505 A JP 2003-124136 A

  In the conventional laser crystallization method, when an attempt is made to form a high-quality and homogeneous semiconductor thin film on the entire surface of a large-sized glass substrate used in the manufacture of an image display device, the instability or non-uniformity of the film, or laser Due to instability and non-uniformity of the irradiation conditions, problems such as partial peeling of the film due to agglomeration in the molten silicon and generation of granular crystals without sufficient lateral growth. appear.

  In particular, when the thickness of the semiconductor thin film is as thin as 200 nm or less, heat from laser irradiation escapes to the substrate side, solidification by cooling proceeds rapidly, and crystal nuclei spontaneously occur before the lateral crystal grows. Large crystal grains could not be obtained. Further, if the laser irradiation time is prolonged or the laser fluence is excessively given, aggregation is likely to occur, and further, thermal stress and damage are given to the underlying film. The state of the molten silicon film on the substrate is greatly affected by the surface state of the substrate, and if there are foreign matter or polishing scratches on the surface of the substrate, the silicon film does not laterally grow and aggregates on the substrate.

FIG. 14 is a schematic diagram for explaining a state in which aggregation occurs due to a concave portion existing on the surface of a conventional substrate. In particular, when the substrate SUB1 is a glass substrate, there are many fine cracks and scratches that occur during surface polishing. A base layer SPL is formed on the substrate SUB1 in order to reduce dangling bonds at the interface between the alkali element and the silicon film from the substrate. The underlayer SPL is formed by continuously forming a silicon nitride film (SiN) and a silicon oxide film (SiO ₂ ) from below by CVD.

  In addition to the above-mentioned minute cracks and scratched concave defects DF, there are convex defects due to the adhesion of foreign substances, but most of the convex defects can be removed by the cleaning process, so that the remaining surface surface Many of the defects are concave defects DF. Since the underlying layer SPL by CVD is formed faithfully on the surface of the substrate, the underlying layer SPL is formed following the shape of the concave defect DF as shown in FIG.

  On this ground layer SPL, an amorphous silicon film is first formed, and this is annealed by pulse laser irradiation to form a precursor film PSI as a crystallized polysilicon film. By applying annealing to the precursor film PSI in one direction S while irradiating the continuous wave laser beam LL, the precursor film PSI is modified to a band-like silicon crystal film SPSI laterally grown in the direction along the scanning direction S. Quality. However, when the concave defect DF exists, the lateral growth of the band-shaped silicon crystal film SPSI is interrupted, and the silicon film melted by the subsequent irradiation with the continuous wave laser beam LL is aggregated by the surface tension. FIG. 14B shows this state. The agglomerated silicon film no longer retains the band-like crystal state, and the agglomerated C portion silicon film does not function as an active layer having a high current mobility of the thin film transistor.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to agglomerate which inhibits formation of the band-like crystal when a band-like crystal silicon film is formed by lateral growth on the substrate of the display device. This is to realize a high-performance display device.

  The present invention improves the surface state of the substrate by providing a coating-type base film on the substrate on which the silicon film is formed, performs scanning and annealing while irradiating continuous wave laser light, and in the growth of the band-shaped crystal in the scanning direction. It is characterized in that the occurrence of aggregation due to the state of the substrate surface is prevented.

An example of the configuration of the present invention is listed as follows. First, for a method of manufacturing a display device according to the present invention,
(1) a base layer forming step of forming a base layer including a coating type insulating film on a substrate; a semiconductor layer forming step of forming a semiconductor layer on the base layer; and a continuous wave laser beam applied to the semiconductor layer A crystallizing step of forming the semiconductor layer into a semiconductor layer made of a band-like crystal by performing annealing that scans while performing irradiation.

(2) A typical example of the semiconductor layer is silicon. The underlayer forming step includes a baking step of applying a polysilazane film, humidifying the surface of the applied polysilazane film, and baking the humidified polysilazane film. The underlayer forming step includes an insulating film coating step for forming a coating type insulating film and an insulating film deposition step for forming a deposition type insulating film by a deposition method.

(3) The coating type insulating film uses any one of an inorganic polymer material, polysilazane, polysilane, siloxane, or a silicon dioxide-based spin-on-glass material.

(4) In the crystallization step, the semiconductor layer is irradiated and scanned while temporally modulating the intensity of the continuous wave laser beam, thereby forming the band-shaped semiconductor crystal in a predetermined region separated from each other. To do. The scanning of the continuous wave laser beam in this crystallization step is performed by moving at least one of the irradiation spot of the continuous wave laser beam on the semiconductor layer or the substrate.

Further, the display device according to the present invention includes:
(5) It has a substrate, a semiconductor crystal, and a base layer including a coating type insulating film formed between the substrate and the semiconductor crystal. This semiconductor crystal is a band-like crystal and typically contains silicon.

(6) The coating type insulating film is SiO _x1 N _y1 (where x1 <y1) on the side close to the substrate, and SiO _x2 N _y2 (where x2 <y2) on the side close to the semiconductor crystal. .

The underlayer includes the coating type insulating film and a deposition type insulating film. The coating type insulating film is an insulating film using any one of an inorganic polymer material, polysilazane, polysilane, siloxane, and a SiO ₂ spin-on-glass material.

  It should be noted that the present invention is not limited to the above-described configuration and the configuration described in the detailed description of the present invention to be described later, and various modifications can be made without departing from the technical idea of the invention described in the claims of the present application. Needless to say, it is possible to make changes.

  According to the manufacturing method of the present invention, the processing speed of the substrate for constituting the display device is greatly improved. By forming a band-like crystal silicon film on the substrate peripheral circuit portion of the display device, a display device having a necessary high-speed operation and highly integrated driving circuit can be configured.

  Embodiments of the present invention will be described below in detail with reference to the drawings of the embodiments. Here, it is assumed that silicon (Si) is mainly used as the semiconductor thin film, but the same effect can be obtained by using a thin film material such as Ge, SiGe, a compound semiconductor, or chalcogenide. In the following embodiment, a general silicon will be described. Further, the present invention is not limited to the modification of an amorphous semiconductor film or a polycrystalline semiconductor film formed on an insulating substrate such as glass for an image display device, but may be applied to another substrate such as a plastic substrate or a silicon wafer. The present invention can be similarly applied to the modification of a similar semiconductor film formed in (1).

Furthermore, it is assumed here that a second harmonic solid-state laser (wavelength λ = 532 nm) of an LD (laser diode) pumped Nd: YVO ₄ laser with continuous oscillation (CW) is used as a laser to be used. A laser having a wavelength that is absorbed by an amorphous or polysilicon semiconductor thin film and having a wavelength in the range of 200 nm to 700 nm is desirable. More specifically, Nd: YAG laser, Nd: YVO ₄ laser, Nd: YLF laser second harmonic, third harmonic, fourth harmonic, and the like can be applied. Considering the stability, the second harmonic of the LD-pumped Nd: YAG laser (wavelength λ = 532 nm) or the second harmonic of the Nd: YVO ₄ laser is most desirable. Similar effects can be obtained by using an excimer laser, Ar laser, semiconductor laser, solid-state pulse laser, or the like.

FIG. 1 is a schematic diagram similar to FIG. 14 for explaining the first embodiment of the present invention. In this embodiment, a coating type base film is used. That is, an insulating film is applied to the surface of the substrate SUB1 to form a base film SPL. The base film SPL is a film mainly composed of silicon oxide SiO ₂ or silicon nitride SiN not containing an alkali metal component. As the material, an inorganic polymer material is suitable, for example, SiO ₂ -based siloxane [SiH (CH ₃ ) O] ₄ , polysilane, SiN-based polysilazane (SiH ₂ NH), and the like. In addition, any silicon oxide SiO ₂ spin-on-glass material that does not contain an alkali metal component can be used.

  By forming the base film by coating, even if there is a recess on the surface of the substrate, it is filled and the surface of the base film SPL is flattened in a self-aligned manner as shown in FIG. An amorphous silicon film is formed by CVD on the planarized base film SPL. This amorphous silicon film is irradiated with excimer laser light to form a polysilicon film PSI. As shown in FIG. 1A, the polysilicon film PSI is used as a precursor film, and the precursor film is scanned relative to the substrate in one direction indicated by an arrow S while irradiating the precursor film with a continuous wave laser beam LL. To do.

  The annealing of the continuous wave laser beam LL causes the crystal grains of the polysilicon film PSI, which is a precursor film, to grow laterally along the scanning direction, and is modified into a band-shaped crystal silicon film SPSI as described with reference to FIG. . At this time, since the surface of the polysilicon film PSI which is the precursor film is flat, the lateral growth is stably continued, and the molten silicon film has no abrupt surface tension change, as shown in FIG. Aggregation does not occur.

FIG. 2 illustrates the laser annealing margin with respect to the laser scanning speed and the laser power in Example 1 of the present invention. FIG. 2 shows the crystal state when the precursor film made of polysilicon is irradiated with excimer laser and a continuous wave laser is irradiated. The horizontal axis indicates the laser scanning speed V (mm / S), and the vertical axis indicates the relative laser power. P _L (au). In FIG. 2, the lower side of the curve a is a granular crystal region (polysilicon region), and the upper side of the curve a is a lateral growth region (band crystal region) by a continuous wave laser.

  Curve b is the upper limit of lateral growth when a precursor film is formed on a substrate having a conventional base film using the insulating film formed by CVD described with reference to FIG. 14 and laser annealing is performed using a continuous wave laser, and curve c is applied. The upper limit of lateral growth when a precursor film is formed on a substrate having a base film of Example 1 of the present invention using a mold insulating film and laser annealing by a continuous wave laser is performed is shown. The upper side of the curve c shows the region where aggregation occurs when a continuous wave laser is used. It should be noted that a region where aggregation occurs when a precursor film is formed on a conventional base film using an insulating film formed by CVD and laser annealing is performed using a continuous wave laser is located above the curve b.

  As shown in FIG. 2, when a precursor film is formed on a substrate having a conventional base film using an insulating film formed by CVD and laser annealing is performed using a continuous wave laser, polishing scratches on the substrate surface, etc. Since the defects are reflected in the precursor film, aggregation occurs unless the power of the continuous wave laser is significantly reduced.

  On the other hand, when the coating type insulating film is used as a base film, aggregation hardly occurs even if the laser power is increased to some extent. In FIG. 2, this is indicated by an arrow A that extends upward from the curve b in the direction of the curve c. However, if the power of the continuous wave laser is too large, the agglomeration occurs through the upper limit curve c. For example, compared to a case where a precursor film is formed on a substrate having a conventional base film using an insulating film by CVD at a laser scanning speed of V = 500 mm / s and laser annealing is performed by a continuous wave laser, When the coating type insulating film is used as a base film, the laser power margin can be expanded 1.5 times in the lateral growth region surrounded by the curves b and c. Alternatively, the lateral growth can be performed without increasing the scanning speed of the laser light so much.

FIG. 3 is a diagram for explaining the relationship between the laser beam width (beam width), the laser annealing margin with respect to the laser power, and the focal depth of the laser in the first embodiment. In the figure, the horizontal axis is the laser beam width W _b (μm), the left vertical axis is the relative laser power density P _L (au), and the right vertical axis is the focal depth F _L (au). . Curve a is the lower limit of the lateral growth region by the continuous oscillation laser when the CVD insulating film is the base film, and curve b is the upper limit of the lateral growth region by the continuous oscillation laser when the CVD insulating film is the base film. c indicates the upper limit of the lateral growth region by the continuous wave laser when the coating type insulating film is used as the base film, and the arrow B indicates the expansion of the lateral growth region similar to the arrow A in FIG. The lower side of the curve a is a granular crystal region, the upper side of the curve c is a region where aggregation occurs, and the straight line D shows a line with a scanning speed V of 300 mm / s.

  As shown in FIG. 3, originally, the narrower the laser beam width and the shorter the beam residence time, the less likely the aggregation occurs, and the wider lateral crystal growth region can be achieved. The annealing process margin can be widened even with high laser power or a wide laser beam width. With a wide laser beam width, a deep depth of focus is obtained as shown in FIG. In the conventional process, in order to prevent the occurrence of agglomeration, the laser width is ideally about 3 to 4 μm. In this case, however, the depth of focus of the laser is considerably shallow, and high precision of substrate scanning over a plane is required. Therefore, variations in the thickness of the substrate may be affected. On the other hand, according to the embodiment of the present invention, by setting the laser width to 5 to 6 μm, the focal depth of the laser is sufficiently deep, and a process margin that can sufficiently cope with variations in the thickness of the substrate is provided. Can be secured.

FIG. 4 is a schematic view similar to FIG. 1 for explaining the second embodiment of the present invention. In this embodiment, the precursor film SPL of the precursor film has a two-layer structure. First, a SiN film is formed as a first layer SPL1 on the glass substrate SUB1 by coating. For the application of the first layer SPL1, it is preferable to use polysilazane containing SiN as a main component, and after baking, baked at 450 ° C. to 490 ° C. in a nitrogen atmosphere to form a SiN film. On this first layer SPL1, a SiO ₂ film and a Si film are continuously laminated by CVD to form a second layer SPL2. Thereafter, the precursor film is scanned while being irradiated with a continuous wave laser to obtain a laterally grown silicon film SPSI of a band-like crystal. According to the second embodiment, the same effect as that of the first embodiment can be obtained.

FIG. 5 is a schematic view similar to FIG. 1 for explaining the third embodiment of the present invention. This embodiment is the same as the embodiment 2 in that the precursor film SPL of the precursor film has a two-layer structure, but the SiN film is formed by CVD as the first layer SPL1, and then the SiO ₂ film is applied. A two-layer SPL2 is assumed. For the second layer SPL2, siloxane or SiO ₂ -based spin-on-glass material is used. As the second layer SPL2, a SiO ₂ film that can be formed by baking polysilazane containing SiN as a main component at 450 ° C. in air or in a water vapor atmosphere may be used.

  In Example 3, since the first layer SPL1 is a SiN film formed by CVD, the barrier property of impurities is very high, and a sufficient impurity barrier property can be exhibited even with a film thickness of about 200 nm. Thereafter, the precursor film is scanned while being irradiated with a continuous wave laser to obtain a laterally grown silicon film SPSI of a band-like crystal. According to the third embodiment, the same effects as those of the first and second embodiments can be obtained.

FIG. 6 is a process diagram for explaining the fourth embodiment of the present invention, and is similar to the second and third embodiments in that the precursor film SPL of the precursor film has a two-layer structure. The second layer SPL2 is also different in that it is formed of a coating type insulating film. As shown in FIG. 6A, polysilazane is applied on the glass substrate SUB1. When this polysilazane coating film is humidified (H ₂ O contact) as shown in FIG. 6B, oxygen is supplied to the film surface, and hydrogen and nitrogen are substituted to bond with silicon Si. Since the reaction proceeds by diffusion in this humidification, if the humidification time normally required for about 5 minutes is interrupted in about 2 minutes, SiO _x N _y suitable for an impurity barrier (where y> x ) First layer SPL1 ′ is formed. On the upper layer side, a second layer SPL2 ′ of SiO _x N _y (where x> y) that forms a clean interface with the silicon film is formed. This can be expressed as: That is, this coating type insulating film is SiO _x1 N _y1 (where x1 <y1) near the substrate, and SiO _x2 N _y2 (where x2 <y2) near the semiconductor crystal.

By firing at 450 ° C. in a nitrogen atmosphere in this state, the first layer SPL1 of the SiN film and the second layer SPL2 of the SiO ₂ film are applied once as shown in FIG. 6C. It is obtained by. In FIG. 6, the first layer SPL1 and the second layer SPL2 constituting the base film SPL are shown as two layers in contact with each other, but in actuality, the film composition reflecting the distribution of oxygen atom diffusion Thus, the composition is such that the SiN film gradually changes into a SiO ₂ film from the lower layer. A silicon precursor film is formed on the base film SPL to obtain a laterally grown belt-like silicon film SPSI modified by continuous wave laser irradiation and scanning.

In Example 4, the base film was applied as a single layer, but the base film may be formed by two coatings. In this case, a SiN film made of polysilazane may be used for the first coating layer, and a SiO ₂ film made of polysilazane or siloxane or other SiO ₂ inorganic polymer may be used for the second coating layer. At this time, after applying twice continuously, the lower polysilazane can be used as it is as a SiN film by baking it. According to the fourth embodiment, the same effects as those of the first to third embodiments can be obtained.

  Hereinafter, an example of a laser beam irradiation device and a display device to be manufactured constituting a manufacturing device for carrying out the present invention will be described. FIG. 7 is an explanatory diagram of an example of a laser beam irradiation apparatus used in the present invention and an arrangement of a modified band-like crystal region (high quality crystallization region) on a substrate, and an example of a laser beam irradiation apparatus and irradiation method. It is a figure for demonstrating. 7A is a configuration diagram of the laser beam irradiation apparatus, FIG. 7B is a plan view for explaining an example of the layout of the modified region, and FIG. 7C is a modulator (EO or EO) in FIG. It is the figure which showed the applied voltage to AO modulator etc.) and the output relationship of a laser beam on the time axis.

  As shown in FIG. 7A, in this laser beam irradiation apparatus, a glass substrate SUB1 on which a semiconductor precursor film PRE (corresponding to PSI in the embodiment) is formed is placed on a stage XYT that drives in the xy directions. Then, alignment is performed using a reference position measuring camera. The reference position measurement signal LEC is input to the control device CRL, fine adjustment of the irradiation position is performed based on the control signal CS input to the drive equipment MD, and the stage XYT is moved at a predetermined speed to scan in one direction. In synchronism with this scanning, laser beam LL is irradiated from the irradiation equipment LU to the precursor PRE of the amorphous silicon or polysilicon film to be modified into a substantially band-like crystalline silicon film SPSI.

  In the irradiation equipment LU, as an example, an oscillator LS of a continuous-wave (CW) solid-state laser excited by a semiconductor diode (LD), an optical system HOS for inputting an output of the laser light L from the oscillator LS, a reflection mirror ML, and a condenser lens system By disposing LZ, an irradiation laser beam having a desired beam width W, beam length N, and intensity distribution can be formed. The optical system HOS includes a beam shaper (homogenizer) and a modulator (for example, an EO or AO modulator) that temporally modulates a continuous wave laser to a predetermined pulse width and / or pulse interval. When the scanning speed V is reduced, a laser beam width W that is narrow, for example, 10 μm or less is required. This can be realized mainly by the condenser lens system LZ. Although the present invention can be implemented without the condensing lens system LZ, the present invention can be more easily realized by inserting the condensing lens system LZ.

  The irradiation time and irradiation intensity of the laser light LL are controlled by the control device CRL. The pulse width and the pulse interval are changed in conjunction with the length and interval of the modified region TL where the lateral crystal is formed. Since the modified region TL formed in this way may be arranged in a tile shape, it may be referred to as a tile TL as described above.

  FIG. 7B shows an example of the layout of the modified region TL made of a semiconductor thin film of a band-like crystal, that is, a laterally grown crystal. Here, a case where a plurality of panels PAN are manufactured from one substrate will be described as an example. A plurality of thin film transistors and circuits are formed in the modified region TL. In this example, the length of the modified region TL corresponds to the length of one side of the panel PAN of the image display device. For example, if the panel PAN is 2.5 inches on one side of the display area PAR, the length is preferably at least 2.5 inches, but may be shorter or longer. Hereinafter, in the x direction, one modified region TL corresponds to a high-performance circuit region CC corresponding to one panel PAN. In the y direction, the necessary circuit arrangement area width is secured by overlapping with a predetermined overlap area width OL. Alternatively, the modified regions TL may be arranged at a predetermined interval (for example, an interval of 5 μm or less). Such an arrangement is realized by intermittently time-modulating the on / off of the laser light with a modulator such as an EO modulator or an AO modulator, for example.

  The relationship between the voltage applied to the EO or AO modulator on the time axis (control voltage) and the output of the laser beam is as shown in the waveform diagram of FIG. 7C when the applied voltage is high (Von). Is set to turn on at low and low. In FIG. 7C, the horizontal axis is time t, the vertical axis is the applied voltage (control voltage) to the modulator (EO / AO modulator), and the lower waveform is the laser output. is there. With this setting, the damage to the modulator is small, and the low noise state at the off time can be used for laser annealing. Since the interval between the panel PANs is small with respect to the length of the high-performance circuit area CC, the laser on time is longer than the off time. Therefore, the ratio (Ton / Toff) of the on time and off time of the voltage to the modulator is 0.1 or less.

  Here, when the current direction of the thin film transistor or the direction connecting the source and the drain and the x direction of the modified region TL are parallel, the thin film transistor has higher performance and a large amount of current flows through the transistor. This is because the crystal grains are composed of band crystals (also referred to as pseudo single crystals) extending in the channel direction. FIG. 13 described above is an example of a thin film transistor corresponding to this.

  As described above, the laser light irradiated onto the substrate is laser light that is time-modulated by a modulator that time-modulates an incident continuous-wave laser according to the control voltage and emits it. When the control voltage is low, the intensity of the incident continuous wave laser is emitted with zero or small change, and when the control voltage is low, the intensity of the incident continuous wave laser is emitted with little change. By irradiating the substrate with laser light time-modulated so that the base pulse width is longer than the pulse interval, the modulator is less damaged and annealing can be performed with less noise laser light.

  FIG. 8 is a schematic cross-sectional view illustrating an example of a thin film transistor formed in a semiconductor film of the present invention. The glass substrate SUB1 has the base film SPL shown in any of the above-described embodiments, and the amorphous silicon or polysilicon precursor formed thereon is irradiated with a continuous wave laser to modify the band-shaped silicon film Two thin film transistors are built in SPSI.

  A gate electrode composed of two layers of metal gate films GT1 and GT2 is formed on the silicon film SPSI via a gate insulating film GI. Implantation NE for controlling the threshold value is performed in the region where the N-type thin film transistor is formed, and implantation PE is performed for controlling the threshold value in the region where the P-type thin film transistor is formed. On top of this, the above-described two-layer metal gate films GT1 and GT2 which will be the gate electrode of the thin film transistor are formed by sputtering or CVD.

  An N type impurity N is implanted to form a source / drain region NSD of the N type thin film transistor. Implantation LDD using the metal gate film GT2 as a mask is performed to form an LDD region NLDD of the N-type thin film transistor. A P-type impurity P is implanted in the source / drain formation region of the P-type thin film transistor to form the source / drain region PSD of the P-type thin film transistor.

  An interlayer insulating film INS1 formed by a CVD method or the like is provided, and wiring is made to each source / drain NSD and PSD of the N-type thin film transistor and the P-type thin film transistor through contact holes formed in the interlayer insulating film INS1 and the gate insulating film GI. A metal layer EL is connected. On this, an interlayer insulating film INS2 is provided, and a protective insulating film PASS is further formed.

  FIG. 9 is an exploded perspective view illustrating a configuration of a liquid crystal display device as a first example of the display device of the present invention. FIG. 10 is a cross-sectional view taken along the line ZZ in FIG. This liquid crystal display device is manufactured using the substrate described above. 9 and 10, reference numeral PNL is a liquid crystal cell in which liquid crystal is sealed in a bonding gap between one substrate SUB1, which is a thin film transistor substrate, and the other substrate SUB2, which is a color filter substrate, and polarizing plates POL1, POL2 Are stacked. Reference numeral OPS is an optical compensation member made of a diffusion sheet or prism sheet, GLB is a light guide plate, CFL is a cold cathode fluorescent lamp, RFS is a reflection sheet, LFS is a lamp reflection sheet, SHD is a shield frame, and MDL is a mold case. is there.

  A liquid crystal alignment film layer is formed on one substrate SUB1, and an alignment regulating force is applied thereto by a technique such as rubbing. After the sealant is formed around the pixel area AR, the other substrate SUB2 on which the alignment film layer is similarly formed is disposed opposite to the gap, a liquid crystal is sealed in the gap, and the sealing agent sealing port is sealed. Close with a stopper. A liquid crystal display device is manufactured by laminating polarizing plates POL1 and POL2 on the front and back of the liquid crystal cell PNL thus configured, and mounting a backlight composed of the light guide plate GLB and the cold cathode fluorescent lamp CFL via the optical compensation member OPS. To do. Note that data and timing signals are supplied to the driving circuit around the liquid crystal cell via the flexible printed boards FPC1 and FPC2. The reference code PCB includes a timing controller for converting a display signal input from the external signal source into a signal format to be displayed on the liquid crystal display device between the external signal source and the flexible printed circuit boards FPC1 and FPC2.

  This liquid crystal display device is suitable for high-speed operation because it has excellent current driving capability by arranging the above-described band-shaped silicon thin film transistor circuit in the pixel circuit. Furthermore, since the variation in threshold voltage is small, the uniformity of image quality is excellent, and a liquid crystal display device can be provided at low cost.

  FIG. 11 is an exploded perspective view illustrating a configuration example of an organic EL display device as a second example of the display device of the present invention. An organic EL element is formed on the electrode in the pixel included in the substrate SUB1 in any of the embodiments described above. The organic EL element is composed of, for example, a laminated body in which a hole transport layer, a light emitting layer, an electron transport layer, a cathode metal layer, and the like are deposited sequentially from the electrode surface in the pixel. A sealing material is disposed around the pixel region PAR of the substrate SUB1 on which such a laminated layer is formed, and sealed with a sealing substrate SUBX or a sealing can. Moreover, you may use a protective film instead of these.

  This organic EL display device supplies display signals from an external signal source to the drive circuit regions DDR and GDR through a printed circuit board PLB. An interface circuit chip CTL is mounted on the printed circuit board PLB. Then, the shield frame SHD as the upper case and the lower case CAS are integrated to form an organic EL display device.

  In the active matrix driving for organic EL display devices, the organic EL element is a current-driven light-emitting method, so the use of a high-performance pixel circuit is essential to provide a high-quality image. It is desirable to use it. A thin film transistor circuit formed in the driver circuit region is also essential for high speed and high definition. The substrate SUB1 has high performance that satisfies such requirements.

It is the same schematic diagram as FIG. 14 explaining Example 1 of this invention. In this embodiment, a coating type base film is used. The laser annealing margin for the laser scanning speed and laser power in Example 1 of the present invention will be described. It is a figure explaining the relationship of the laser annealing margin with respect to the laser beam width (beam width), the laser power, and the focal depth of the laser in Example 1 of the present invention. It is the same schematic diagram as FIG. 1 explaining Example 2 of this invention. It is the same schematic diagram as FIG. 1 explaining Example 3 of this invention. It is a process figure explaining Example 4 of this invention. It is explanatory drawing of the example of the irradiation apparatus of the laser beam used for this invention, and arrangement | positioning of the strip | belt-shaped crystal | crystallization area | region (high quality crystallization area | region) on a board | substrate. It is a cross-sectional schematic diagram explaining an example of the thin-film transistor built in the semiconductor film of this invention. It is an expansion | deployment perspective view explaining the structure of the liquid crystal display device as a 1st example of the display apparatus of this invention. It is sectional drawing cut | disconnected in the ZZ line direction of FIG. It is an expansion | deployment perspective view explaining the structural example of the organic electroluminescent display apparatus as a 2nd example of the display apparatus of this invention. It is explanatory drawing of the modification | reformation method to the band-like crystallization of the silicon film which uses continuous wave laser beam irradiation. It is a schematic diagram showing a crystal structure of a band-shaped crystal silicon film obtained by irradiation of continuous wave laser light and an electrode arrangement example of a thin film transistor formed in this sheet film. It is a schematic diagram explaining a mode that aggregation arises by the recessed part which exists in the conventional substrate surface.

Explanation of symbols

SUB1 ... substrate, SPL ... underlayer, DF ... concave defect, TL ... modified region, LL ... continuous wave laser beam, SPSI ... belt-like crystalline silicon Film, PSI ... Polysilicon film (precursor film).

Claims (13)

A base layer forming step of forming a base layer including a coating type insulating film on the substrate;
A semiconductor layer forming step of forming a semiconductor layer on the underlayer;
A method of manufacturing a display device, comprising: a crystallization step in which the semiconductor layer is scanned while being irradiated with a continuous wave laser beam so that the semiconductor layer is a semiconductor layer made of a band crystal.   The method for manufacturing a display device according to claim 1, wherein the semiconductor layer contains silicon.   3. The underlayer forming step includes a baking step of applying a polysilazane film, humidifying a surface of the applied polysilazane film, and baking the humidified polysilazane film. Method of manufacturing the display device.   4. The underlayer forming step includes an insulating film coating step for forming a coating type insulating film, and an insulating film deposition step for forming a deposition type insulating film by a deposition method. The manufacturing method of the display apparatus as described in 1 ..   5. The coating type insulating film is an insulating film using any one of an inorganic polymer material, polysilazane, polysilane, siloxane, or a silicon dioxide-based spin-on-glass material. The manufacturing method of the display apparatus in any one of.   The crystallization step is a step of forming the band-like semiconductor crystal in a predetermined region separated from each other by irradiating and scanning the semiconductor layer while temporally modulating the intensity of the continuous wave laser beam. The method for manufacturing a display device according to claim 1, wherein the display device is provided.   7. The scanning of the continuous wave laser beam in the crystallization step is performed by moving at least one of an irradiation spot of the continuous wave laser beam on the semiconductor layer or the substrate. A method for manufacturing the display device according to claim 1. A substrate,
A semiconductor crystal;
A display device comprising: a base layer including a coating type insulating film formed between the substrate and the semiconductor crystal.   The display device according to claim 8, wherein the semiconductor crystal is a band crystal.   The display device according to claim 8, wherein the semiconductor crystal contains silicon. The coating type insulating film is SiO _x1 N _y1 (where x1 <y1) near the substrate, and SiO _x2 N _y2 (where x2 <y2) near the semiconductor crystal. The display device according to claim 8 or 9.   The display device according to claim 8, wherein the base layer includes the coating type insulating film and a deposition type insulating film. The coating type insulating film is an insulating film using any one of an inorganic polymer material, polysilazane, polysilane, siloxane, and a SiO ₂ spin-on-glass material. A display device according to any one of the above.

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