JP2008275879A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device wherein reliability of electric connection between a pad part connected to the source electrode of a thin film transistor and a pixel electrode via a through-hole is secured. <P>SOLUTION: At least a semiconductor layer, the pad part connected to the source electrode of the thin film transistor, an insulating film, and the pixel electrode are laminated in order on a substrate. The pixel electrode is electrically connected to the pad par via the through-hole formed in the insulating film. The pad part has a cut or a hole formed by crossing a part of a periphery of an opening end on the pad part side of the through-hole. The semiconductor layer on the lower layer of the pad part is formed so as to extend beyond the formation region of the cut or the hole of the pad part and the pad part, and a step reflecting a recessed part due to the cut or the hole formed in the pad part is formed around the opening end on a surface of the insulating film, of the through hole. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a display device, and more particularly to a display device having a configuration in which a signal is supplied to a pixel electrode formed on an insulating film through a through hole formed in the insulating film.

  For example, an active matrix type liquid crystal display device sequentially selects each pixel column by turning on a thin film transistor provided in each pixel by a scanning signal supplied via a common gate signal line. Accordingly, a video signal is supplied to each pixel in the pixel column via a drain signal line commonly connected to the corresponding pixel in the other pixel column.

  The video signal is supplied to one electrode (pixel electrode) of a pair of electrodes formed in each pixel, and a voltage with the other electrode (counter electrode) to which a signal serving as a reference for the video signal is supplied The liquid crystal molecules of the pixel are caused to behave by an electric field generated according to the difference.

  In this case, the thin film transistor is usually formed by being covered with an insulating film in order to avoid direct contact with the liquid crystal, and the pixel electrode is usually formed on the upper surface of the insulating film.

  Therefore, the pixel electrode is configured to be connected to one electrode (source electrode) of the thin film transistor through a through hole formed in the insulating film, and a video signal from a drain signal line passes through the thin film transistor. The pixel electrode is supplied.

A liquid crystal display device having such a configuration is disclosed in, for example, Patent Document 1 below.
JP 2002-49049 A

  In the liquid crystal display device having such a configuration, in recent years, it has been demanded to reduce the diameter of the through hole formed in the insulating film. This is for minimizing each pixel and improving the aperture ratio.

  However, it has been pointed out that when the diameter of the through hole formed in the insulating film is reduced, the pixel electrode cannot be electrically connected to the source electrode of the thin film transistor in the through hole with high reliability.

  That is, when a conductive layer is formed on the insulating film and the pixel electrode is formed by selective etching using a photolithography technique, a step of applying a photoresist on the upper surface of the conductive layer is required. In this case, the conductor layer is in a state in which a concave portion is formed in a portion where the through hole of the insulating film is formed, but a phenomenon occurs in which it becomes difficult to fill the concave portion with a liquid photoresist. For this reason, a hole is opened in the photoresist film used as a mask in selective etching, and the conductor layer formed in the through hole portion of the insulating film is etched through the hole.

  In the case of a liquid crystal display device, it is common to form an alignment film on the upper surface of the insulating film covering the pixel electrode. This is because it is necessary to determine the initial alignment direction of liquid crystal molecules that are in direct contact with the alignment film.

  Even in this case, it has been pointed out that the alignment film cannot be formed with high reliability in the through-hole portion of the insulating film.

  That is, after the pixel electrode is formed, a process of applying a resin, which is a material for the alignment film, is required. In this case, the pixel electrode is in a state in which a recess is formed in the through hole formation portion of the insulating film. However, this is because a phenomenon that it becomes difficult to fill the recess with liquid resin occurs.

  An object of the present invention is to provide a display device that achieves reliability of electrical connection through a through-hole between a pad portion connected to a source electrode of a thin film transistor and a pixel electrode.

  An object of the present invention is to provide a liquid crystal display device capable of forming an alignment film with high reliability.

   Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.

(1) In the display device according to the present invention, for example, at least a semiconductor layer, a pad portion connected to a source electrode of a thin film transistor, an insulating film, and a pixel electrode are sequentially stacked on a substrate.
The pixel electrode is electrically connected to the pad portion through a through hole formed in the insulating film,
The semiconductor layer under the pad portion has a notch or a hole formed at a position overlapping the wall surface of the through hole,
A step is formed around the opening end of the through hole, reflecting a notch formed in the semiconductor layer or a recess due to a hole.

(2) The display device according to the present invention is based on, for example, the configuration of (1), and the semiconductor layer is a deformed photoresist film obtained by reflowing the photoresist film used for patterning the pad portion. It is characterized by being patterned by etching using as a mask.

(3) The display device according to the present invention is based on, for example, the configuration of (1), and the notch formed in the semiconductor layer overlaps with the periphery of the open end of the through hole on the pad portion side. At least one is formed.

(4) The display device according to the present invention is premised on, for example, the configuration of (1), and the hole formed in the semiconductor layer is at least at a position overlapping with the periphery of the opening end of the through hole on the pad portion side. One is formed.

(5) The display device according to the present invention is, for example, on the premise of the configuration of (4), and the holes are arcuate.

(6) The display device according to the present invention is premised on, for example, the configuration of (4), and the holes have a cross shape.

(7) The display device according to the present invention is based on, for example, the configuration of (1), and the display device is composed of a liquid crystal display device, and an alignment film is formed on the liquid crystal side surface of the substrate on which the pixel electrodes are formed It is characterized by being.

  In addition, this invention is not limited to the above structure, A various change is possible in the range which does not deviate from the technical idea of this invention.

  The display device configured as described above can improve the reliability of electrical connection through the through hole between the pad portion connected to the source electrode of the thin film transistor and the pixel electrode.

  The display device configured as described above can reliably form the photoresist and the alignment film in the through-hole portion.

  Embodiments of a display device according to the present invention will be described below with reference to the drawings.

<Overall configuration>
FIG. 2 shows a liquid crystal display device as an example of a display device according to the present invention, and is a schematic plan view showing an embodiment of the liquid crystal display device.

  In FIG. 2, the liquid crystal display device uses a pair of, for example, glass substrates SUB1 and SUB2 arranged in parallel as an envelope, and a liquid crystal (not shown) is interposed between the substrates SUB1 and SUB2. .

  The liquid crystal is enclosed by a sealing material SL that also serves to fix the substrate SUB2 to the substrate SUB1, and a region surrounded by the sealing material SL constitutes a liquid crystal display area AR.

  For example, the substrate SUB1 has a larger area than the substrate SUB2 and has regions exposed from the substrate SUB2 on the left side and the upper side in the drawing. This is because the scanning signal drive circuit V made up of a plurality of parallel semiconductor devices is mounted on the left side of the substrate SUB1, and the video signal drive circuit He made up of a plurality of parallel semiconductor devices is mounted on the upper side. .

  A drain signal line DL extending in the x direction and arranged in parallel in the y direction in the liquid crystal display area AR on the liquid crystal side of the substrate SUB1 is also extended in the y direction and extends in the x direction. Gate signal lines GL arranged in parallel to each other are formed.

  A rectangular region surrounded by the gate signal line GL and the drain signal line DL constitutes a region where pixels are formed, whereby each pixel is arranged in a matrix in the liquid crystal display region AR.

  Each of the gate signal lines GL has, for example, a left end extending beyond the sealing material SL to the outside of the liquid crystal display area AR and connected to the scanning signal driving circuit V. (Voltage) is supplied.

  Each drain signal line DL has, for example, an upper end that extends beyond the sealing material SL to the outside of the liquid crystal display area AR and is connected to the video signal drive circuit He. (Voltage) is supplied.

  As shown by a dotted circle P ′ which is an enlarged view of a dotted circle P surrounding the one pixel, the pixel includes a thin film transistor TFT which is turned on by a scanning signal from the gate signal line GL, and this turned on. A pixel electrode PX to which a video signal from the drain signal line DL is supplied via the thin film transistor TFT and a counter electrode CT for generating an electric field between the pixel electrode PX when a reference voltage is applied are provided. The electric field includes an electric field component parallel to the surface of the substrate SUB1, and a device that causes liquid crystal molecules to behave by such an electric field is called a transverse electric field method.

  Note that a reference voltage is applied to the counter electrode CT through, for example, a common signal line CL arranged in parallel with the gate signal line GL, and the common signal line CL extends beyond the seal material SL. And connected to a common terminal CTM formed on the surface of the substrate SUB1.

  In the embodiment described above, the scanning signal drive circuit V and the video signal drive circuit He are configured to be mounted on the substrate SUB1. However, the present invention is not limited to this, and a semiconductor device configured by a so-called tape carrier method (a semiconductor device in which a semiconductor chip is mounted on a flexible substrate) is disposed across the substrate SUB1 and a printed circuit board (not shown). It may be configured.

<Pixel configuration>
FIG. 1 is a plan view showing an embodiment of one of the pixels arranged in a matrix on the substrate SUB1 side of the liquid crystal display panel PNL. Thereby, each pixel arrange | positioned with respect to the said pixel shown in FIG. 1 on each of the upper and lower sides, and right and left has the structure similar to the said pixel.

  3 (a) and 3 (b) are cross-sectional views taken along line III (a) -III (a) in FIG. 1, respectively, and are cross-sectional views taken along line III (b) -III (b) in FIG. The figure is shown.

  First, the gate signal line GL and the common signal line CL are formed in parallel with a relatively large distance on the liquid crystal side surface (front surface) of the substrate SUB1.

  In a region between the gate signal line GL and the common signal line CL, a counter electrode CT made of, for example, an ITO (Indium-Tin-Oxide) transparent conductive material is formed. The counter electrode CT is formed so as to be superimposed on the common signal line CL at a side portion on the common signal line CL side, and is thereby electrically connected to the common signal line CL.

  An insulating film GI (see FIG. 3) is formed on the surface of the substrate SUB1 so as to cover the gate signal line GL, the common signal line CL, and the counter electrode CT. This insulating film GI functions as a gate insulating film of the thin film transistor TFT in a formation region of the thin film transistor TFT described later, and the film thickness and the like are set accordingly.

  An amorphous semiconductor layer AS made of, for example, amorphous silicon is formed on the upper surface of the insulating film GI where it overlaps with a part of the gate signal line GL. The semiconductor layer AS is a semiconductor layer of the thin film transistor TFT.

  The semiconductor layer AS is not limited to the formation region of the thin film transistor TFT, but below the drain signal line DL, below the connection portion JC that electrically connects the drain signal line DL and the drain electrode DT of the thin film transistor TFT, In addition, the thin film transistor TFT is formed below the source electrode ST of the thin film transistor TFT below the portion (including the pad portion PD) extending beyond the region where the thin film transistor TFT is formed. Such a semiconductor layer AS is formed in the above-described pattern by forming the thin film transistor TFT by, for example, a registry flow method. For example, the drain signal line DL can be formed with a small level difference and an effect of avoiding a so-called disconnection problem. Play. In the following description, a semiconductor layer formed in a region other than the region where the thin film transistor TFT is formed in the semiconductor layer AS may be denoted by reference numeral AS ′.

  Then, a drain signal line DL is formed extending in the y direction in the figure, and this drain signal line DL has an extension portion extending partly toward the thin film transistor TFT, and this extension portion (connection portion) JC) is connected to the drain electrode DT of the thin film transistor TFT formed on the semiconductor layer AS.

  Further, the source electrode ST formed simultaneously with the formation of the drain signal line DL and the drain electrode DT is opposed to the drain electrode DT on the semiconductor layer AS, and from the semiconductor layer AS to the pixel region. It is formed with an extending portion that extends slightly to the side. This extending portion is configured to reach a pad portion PD connected to a pixel electrode PX described later.

  The drain electrode DT is formed, for example, as a U-shaped pattern formed so as to surround the tip of the source electrode ST. Thereby, the channel width of the thin film transistor TFT can be increased.

  When the semiconductor layer AS is formed on the insulating film GI, for example, the surface thereof is formed by doping a high concentration impurity. For example, the drain electrode DT and the source electrode ST are patterned. After the formation, the high concentration impurity layer formed in a region other than the region where the drain electrode DT and the source electrode ST are formed is etched using the photoresist film on the drain electrode DT and the source electrode ST as a mask. . This is because a high-concentration impurity layer (for example, shown as a high-concentration impurity layer CNL in FIG. 5) is left between the semiconductor layer AS and the drain electrode DT and the source electrode ST, and this impurity layer is formed as an ohmic contact layer. is there.

  By doing so, the thin film transistor TFT constitutes a transistor having a so-called inverted staggered MIS (Metal Insulator Semiconductor) structure using the gate signal line GL as a gate electrode.

  Note that the transistor having the MIS structure is driven so that the drain electrode DT and the source electrode ST are switched by application of the bias. However, in the description of this specification, the transistor is connected to the drain signal line DL for convenience. The side connected to the drain electrode DT and the side connected to the pixel electrode PX are called the source electrode ST.

  On the surface of the substrate SUB, a protective film PAS (see FIG. 3) made of an insulating film covering the thin film transistor TFT is formed. The protective film PAS is provided in order to prevent the thin film transistor TFT from coming into direct contact with the liquid crystal. Further, the protective film PAS is provided as an intervening layer between the counter electrode CT and a pixel electrode PX, which will be described later, and a capacitor provided between the counter electrode CT and the pixel electrode PX together with the insulating film GI. It also functions as a dielectric film of the element.

  A pixel electrode PX is formed on the upper surface of the protective film PAS. The pixel electrode PX is made of a transparent conductive film such as ITO (Indium-Tin-Oxide), for example, and is formed so as to overlap the counter electrode CT over a wide area.

  The pixel electrode PX is formed so as to have an electrode group composed of a large number of strip-shaped electrodes in which a large number of slits are juxtaposed in a direction crossing the longitudinal direction thereof, and both ends thereof are connected to each other. Has been.

  As shown in FIG. 1, each electrode of the pixel electrode PX divides a pixel region into, for example, two parts in the upper and lower directions in the figure, and one region has a + 45 ° direction with respect to the traveling direction of the gate signal line GL, for example The other region is formed so as to extend in the −45 ° direction. A so-called multi-domain method is adopted, and when the direction of the slit provided in the pixel electrode PX in one pixel (the direction of the electrode group of the pixel electrode PX) is single, the problem of coloring due to the viewing direction is eliminated. It has become the composition.

  The pixel electrode PX thus formed is electrically connected to the pad portion PD of the source electrode ST of the thin film transistor TFT through the through hole TH formed in the protective film PAS on the side portion on the thin film transistor TFT side. It has become.

  Here, in this embodiment, as shown by a dotted round frame Q ′ obtained by enlarging the dotted round frame Q in the drawing, the pad portion PD has a central portion of the pad portion PD at a part of its periphery. Thus, a pair of notches CTM are formed so as to face each other.

  Each notch CTM is formed so that the tip thereof is directed to the center of the pad portion PD and extends sufficiently to the formation portion of the through hole TH of the protective film PAS. In other words, each notch CTM is formed so as to intersect a part of the periphery of the opening end of the through hole TH on the bottom surface side of the protective film PAS.

  In this way, the notch is formed in the pad portion PD when the protective film PAS is formed covering the pad portion PD by the notch CTM of the pad portion PD on the surface of the protective film PAS. This is because when the formed recessed portion is reflected (floated) and then the through hole TH is formed, each recessed portion is formed adjacent to the opening end of the through hole TH.

  FIG. 4A is a perspective view showing the surface of the protective film PAS in which the through hole TH is formed. The recessed portion DNT formed adjacent to the periphery of the opening end of the through hole TH on the surface of the protective film PAS is a recessed portion formed by a notch CTM formed in the pad portion PD (the bottom surface is a semiconductor layer). AS ′) is reflected (floated) when the surface of the protective film PAS is formed. Here, in this specification, the reflection means that when the deposited layer is formed on the underlying layer having an uneven surface by, for example, the CVD method, the uneven surface of the underlying layer is exposed corresponding to the surface of the deposited layer. The phenomenon that becomes.

  Further, on the surface of the protective film PAS shown in FIG. 4A, as shown in FIG. 4B, an ITO film (indicated by reference numeral IT in FIG. 7) and a pixel electrode PX processed with this ITO film are formed. Although the pixel electrode PX is also formed, a recess TH ′ is formed on the surface of the pixel electrode PX in the formation region of the through hole TH, and the recess DNT ′ is adjacent to the periphery of the opening end of the recess TH ′. Will be formed. The recessed portion DNT ′ is formed by reflecting (floating) the recessed portion DNT of the protective film PAS.

  Note that the semiconductor layer AS 'disposed below the pad portion PD is formed so that the periphery thereof protrudes outward from the outline of the pad portion PD. The semiconductor layer AS ′ is formed over the entire area of the notch CTM portion of the pad portion PD, so that the notch CTM portion of the pad portion PD has the semiconductor layer AS ′ as the bottom surface. A recessed part will be formed.

  The semiconductor layer AS 'is formed in such a pattern because the thin film transistor TFT or the like is formed by a registry flow method. A method of manufacturing the display device by this registry flow method will be described later.

  Further, an alignment film ORI1 (see FIG. 3) is formed on the surface of the substrate SUB1 so as to cover the pixel electrode PX, and the initial alignment direction of the molecules of the liquid crystal that directly contacts the alignment film ORI1 by the alignment film ORI1. Is set.

  In the above-described embodiment, amorphous silicon is used as the semiconductor layers AS and AS '. However, the present invention is not limited to this, and may be polysilicon or the like.

<Production method>
5 to 7 are process diagrams showing an embodiment of a method for manufacturing the above-described liquid crystal display device in the thin film transistor TFT portion. Each of the process diagrams shown in FIG. 5 to FIG. 7 shows a cross section of a portion corresponding to the line VV in FIG. 1 on the left side and a cross section of a portion corresponding to the line VIII-VIII in FIG. In this embodiment, the thin film transistor TFT is formed by selective etching called a so-called registry flow method.

  First, as shown in FIG. 5A, the gate signal line GL, the common signal line CL, the counter electrode CT, and the gate signal line GL, the common signal line CL, the counter electrode CT are provided on the main surface (surface on the liquid crystal side). A substrate SUB1 on which an insulating film GI is formed is prepared.

  Then, the semiconductor layer AS and the conductor layer CDT are sequentially stacked over the entire upper surface of the insulating film GI of the substrate SUB1 by using, for example, a CVD method.

  Here, the semiconductor layer AS is made of, for example, amorphous Si, and the surface thereof is formed to have a high concentration impurity layer CNL doped with a high concentration n-type impurity. The high-concentration impurity layer CNL functions as an ohmic contact layer in the region where the thin film transistor TFT is formed.

  Next, as shown in FIG. 5B, a photoresist film PTR is applied to the entire surface of the conductor layer CDT, and the photoresist film PTR is selectively removed by a well-known photolithography technique to form a pattern. Turn into. Here, the pattern of the remaining photoresist film PTR is the same as the pattern to be left by selective etching of the conductor layer CDT.

  Next, as shown in FIG. 5C, the conductor layer CDT and the high concentration impurity layer CNL are sequentially etched using the remaining photoresist film PTR as a mask. Here, for example, wet etching is used for the conductor layer CDT, and dry etching is used for the high concentration impurity layer CNL. In this case, although not clearly shown in FIG. 5, the pad portion PD of the source electrode ST of the thin film transistor TFT is selectively etched in a pattern having the cutout portion CTM as shown in FIG. .

  Next, as shown in FIG. 5D, the photoresist film PTR is reflowed to form a modified photoresist film PTR '. The deformed photoresist film PTR ′ by this reflow, for example, exposes the photoresist film PTR to the vapor of the organic solvent solution for 1 to 3 minutes, thereby gradually infiltrating the organic solvent solution into the photoresist film PTR, The photoresist film PTR is formed so as to be dissolved.

  By this reflow, the photoresist film PTR formed above the patterned conductor layer CDT flows out of the ring of the conductor layer CDT and flows. As a result, the photoresist film PTR also flows over the semiconductor layer AS corresponding to the channel region between the drain electrode DT and the source electrode ST, and also covers this portion. The photoresist film PTR also flows over the semiconductor layer AS of the notch portion CTM of the pad portion PD of the source electrode ST of the thin film transistor TFT and covers this portion.

  Next, as shown in FIG. 6E, using the reflowed photoresist film PTR 'as a mask, the semiconductor layer AS exposed from the mask is etched using dry etching such as ashing, for example.

  In this case, the outer contour of the semiconductor layer AS ′ positioned under the pad portion PD is formed as a pattern as shown in FIG. 1 by etching using the deformed photoresist film PTR ′ as a mask. .

  Then, in the portion of the notch portion CTM of the pad portion PD, a recessed portion whose bottom surface is the surface of the semiconductor layer AS ′ exposed by the formation of the notch portion CTM is formed.

  Then, as shown in FIG. 6F, the formation of the thin film transistor TFT is completed by removing the photoresist film PTR '. The thin film transistor TFT is formed in a state where the drain electrode DT is connected to the drain signal line DL and the source electrode ST is connected to the pad portion PD.

  Thereafter, as shown in FIG. 6G, a protective film PAS made of SiN, for example, is formed on the surface of the substrate SUB1 by covering the thin film transistor TFT by, for example, the CVD method. In this case, the surface of the protective film PAS is formed by reflecting (floating) the surface irregularities of the layer serving as a base when the protective film PAS is formed in an almost intact state. For this reason, the recessed portion formed in the notch portion CTM of the pad portion PD is reflected and reflected on the surface of the protective film PAS formed on the upper surface of the pad portion PD.

  Next, as shown in FIG. 6H, a through hole TH is formed in the protective film PAS, and the central portion of the pad portion PD of the source electrode ST of the thin film transistor TFT is exposed from the through hole TH. In this case, a part of the notch CTM formed in the pad portion PD is also exposed from the through hole TH. A step is formed around the opening end of the through hole TH on the surface of the protective film PAS due to the presence of the notch CTM.

  That is, as shown in FIG. 4A, the surface of the protective film PAS in which the through hole TH is formed is recessed by reflecting (floating) the recessed portion due to the notched portion CTM of the pad portion PD. A portion DNT is formed, and a step is formed around the open end of the through hole TH by the recessed portion DNT.

  Next, as shown in FIG. 7I, an ITO film IT is formed over the entire upper surface of the protective film PAS by, for example, a sputtering method. In this case, the ITO film IT formed in the through hole TH formed in the protective film PAS is formed to have a thickness substantially the same as the thickness of the ITO film formed in a region other than the through hole TH. As shown in FIG. 4B, a recess TH ′ and a recess DNT ′ are formed on the surface of the ITO film IN at the through hole TH.

  Then, as shown in FIG. 7J, a liquid photoresist is applied over the entire upper surface of the ITO film IT to form a photoresist film PTR. Further, the photoresist film PTR on the region where the pixel electrode PX is formed in the ITO film IT is left, and the other photoresist films are removed.

  Thereafter, the remaining photoresist film PTR is used as a mask, and the ITO film IT exposed from the mask is removed by etching.

  Here, in the application of the liquid photoresist in this step, a concave portion TH ′ is formed in the connection portion between the ITO film IT and the source electrode ST of the thin film transistor TFT as shown in FIG. 4B. However, the filling of the photoresist into the recess TH ′ is smoothly performed from the stepped portion by the recess DNT ′ provided around the opening end of the recess TH ′. This is probably because the surface tension of the photoresist that works to prevent the flow to the recessed portion DNT 'around the opening end of the recessed portion DNT' can be greatly attenuated by the step.

  Accordingly, a reliable mask is formed in the through hole TH portion of the protective film PAS, and the pixel electrode PX formed by the ITO film IT is electrically connected to the source electrode ST of the thin film transistor TFT through the through hole TH. Connection can be achieved.

  Next, as shown in FIG. 7 (k), the photoresist film PTR, which has become a mask when the pixel electrode PX is formed, is removed.

  Next, as shown in FIG. 7L, an alignment film ORI1 is formed on the surface of the substrate SUB1 so as to cover the pixel electrode PX. This alignment film ORI1 is formed by first forming a resin film by applying a liquid resin by, for example, an ink jet method and rubbing the surface.

  Here, in the application of the liquid resin in this step, the connection portion between the pixel electrode PX and the source electrode ST of the thin film transistor TFT is formed with the recess TH ′ as shown in FIG. The filling of the recess TH ′ with the resin is smoothly performed from the stepped portion by the recess DNT ′ provided around the opening end of the recess TH ′. This is probably because the surface tension of the resin that works to prevent the flow to the recessed portion DNT 'around the opening end of the recessed portion DNT' can be greatly attenuated by the step.

  From this, the alignment film ORI is free from the occurrence of a concave defect due to the resin not flowing into the recess TH ′, and therefore, it is possible to avoid causing an alignment abnormality in the through hole TH. Become.

  As is apparent from the above description, the liquid crystal display device manufactured in this way can achieve reliability of electrical connection through the through hole between the pad portion connected to the source electrode of the thin film transistor and the pixel electrode. In addition, the alignment film can be formed with high reliability.

<Other Examples>
In the embodiment described above, the notch portion CTM formed in the pad portion PD of the source electrode ST of the thin film transistor TFT is formed as a pair of opposingly arranged toward the center of the pad portion PD. However, the cutout portion CTM may be formed as three or more, or may be one as shown in FIG. This is because the same effect can be achieved though there is a difference in effect.

  Further, the pad portion PD is not limited to a notch, and may be a hole formed by crossing a part of the periphery of the opening end on the bottom surface side of the protective film PAS of the through hole TH. . The concave portion formed by the hole (the bottom surface is the semiconductor layer AS ′) is reflected (floated) on a part of the periphery of the opening end on the surface side of the protective film PAS of the through hole TH to form a step. Because.

  In this case, for example, as shown in FIG. 8B, the hole HL formed in the pad portion PD is a portion having a relatively long arc length around the opening end of the through hole TH on the bottom surface side of the protective film PAS. You may form so that it may arrange | position inside this hole HL. For example, as shown in FIG. 8C, the hole HL formed in the pad portion PD is formed by dividing a plurality of divided arc portions around the opening end on the bottom surface side of the protective film PAS of the through hole TH. You may form so that it may arrange | position inside this hole HL.

  In the above-described embodiments, the display device according to the present invention has been described using a liquid crystal display device as an embodiment. However, the present invention can also be applied to other display devices such as an organic EL (Electro Luminescence) device. Some organic EL devices include a thin film transistor for each pixel, and the pad portion of the source electrode is electrically connected through a pixel electrode disposed with an insulating film interposed therebetween and a through hole formed in the insulating film. It is because it is the structure connected to.

  Each of the embodiments described above may be used alone or in combination. This is because the effects of the respective embodiments can be achieved independently or synergistically.

It is a top view which shows one Example of a structure of the pixel of the display apparatus by this invention. It is a schematic block diagram which shows one Example of the display apparatus by this invention. FIG. 3 is a cross-sectional view taken along line III (a) -III (a) and line III (b) -III (b) in FIG. 1. FIG. 4 is a perspective view in the vicinity of a through hole of a protective film, and a perspective view in the vicinity of a through hole portion of a pixel electrode. It is a figure which shows a part of manufacturing method of the display apparatus by this invention, and is a figure which showed each process with FIG. 6 and FIG. It is a figure which shows a part of manufacturing method of the display apparatus by this invention, and is a figure which showed each process with FIG. 5 and FIG. It is a figure which shows a part of manufacturing method of the display apparatus by this invention, and is a figure which showed each process with FIG. 5 and FIG. It is a principal part block diagram which shows the other Example of the display apparatus by this invention.

Explanation of symbols

SUB1, SUB2 ... Substrate, SL ... Seal material, GL ... Gate signal line, DL ... Drain signal line, CL ... Common signal line, TFT ... Thin film transistor, PX ... Pixel electrode, CT ... Counter electrode DT ...... Drain electrode ST ST Source electrode AS AS AS Semiconductor layer PD Pad part CTM Notch TH TH Through hole GI Insulating film PAS Protective film, HL ... hole.

Claims (7)

On the substrate, at least a semiconductor layer, a pad portion connected to the source electrode of the thin film transistor, an insulating film, and a pixel electrode are sequentially stacked,
The pixel electrode is electrically connected to the pad portion through a through hole formed in the insulating film,
The semiconductor layer under the pad portion has a notch or a hole formed at a position overlapping the wall surface of the through hole,
A display device is characterized in that a step is formed around the opening end of the through hole, reflecting a notch or a recess formed by a hole formed in the semiconductor layer.   2. The semiconductor layer according to claim 1, wherein the semiconductor layer is patterned by etching using a modified photoresist film obtained by reflowing a photoresist film used in patterning the pad portion as a mask. Display device.   The display device according to claim 1, wherein at least one notch formed in the semiconductor layer is formed at a position overlapping with a periphery of an opening end of the through hole on the pad portion side.   The display device according to claim 1, wherein at least one hole formed in the semiconductor layer is formed at a position overlapping with a periphery of an opening end of the through hole on the pad portion side.   The display device according to claim 4, wherein the hole has an arcuate shape.   The display device according to claim 4, wherein the hole has a cross shape.   The display device according to claim 1, wherein the display device is a liquid crystal display device, and an alignment film is formed on a surface of the substrate on the liquid crystal side where the pixel electrode is formed.

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