JP4567385B2 - Manufacturing method of liquid crystal display device - Google Patents

Description

The present invention relates to a method for manufacturing a liquid crystal display equipment provided with a TFT element.

  A conventional liquid crystal display device provided with a thin film transistor (hereinafter referred to as TFT) element for pixel switching is shown in FIG. The liquid crystal display device X includes a semiconductor layer 92 constituting the TFT element 91, and a part of the semiconductor layer 92 is a channel region 92a. When the liquid crystal display device X is used, when light from an illuminating device (not shown) for illuminating the liquid crystal layer 93 enters the channel region 92a, a photocurrent is generated in the channel region 92a due to a photoelectric conversion effect. The function of the TFT element 91 is not properly exhibited. In the liquid crystal display device X, a lower light shielding film 94 is provided as a light shielding measure under the channel region 92a. As a light shielding measure above the channel region 92a, the data line 95a and the capacitor line 95b are formed so as to cover the TFT element 91, and the data line 95a and the capacitor line 95b are also used as the upper light shielding film 95. ing.

  However, a plurality of light-transmitting films such as the insulating film 96 are stacked on the substrate 90 in a complicated shape. For this reason, for example, light incident on the insulating film 96 at a position away from the TFT element 91 to the side thereof may be refracted and reflected repeatedly to be irradiated to the channel region 92a. For such light, the lower light-shielding film 94 and the upper light-shielding film 95 do not have a light-shielding effect, so that the above photocurrent is generated, and it is difficult to appropriately exert the function of the TFT element 91. Met.

Japanese Patent Laid-Open No. 2002-124679 (FIG. 3)

The present invention, which has been proposed under the circumstances described above, to prevent the generation of photocurrent by light leakage, a method of manufacturing a liquid crystal display equipment capable of appropriately preventing the characteristics of the TFT element The issue is to provide

  In order to solve the above problems, the present invention takes the following technical means.

Method of manufacturing a liquid crystal display device which is in the onset Ming Thus provided is a method of manufacturing a liquid crystal display device having a step of forming a semiconductor layer that constitutes the TFT elements on a substrate, the step of forming the semiconductor layer Later, as a step of forming a frame-like portion surrounding the semiconductor layer on the substrate, and a thin film forming method having directivity along a direction inclined with respect to a direction orthogonal to the substrate from four directions surrounding the semiconductor layer And a step of forming a light-shielding film on the inward side surface of the frame-like portion by performing the sputtering method or the vapor deposition method .

According to such a configuration, in the formation of the light shielding film, the light shielding film can be appropriately formed on the inward side surface of the frame-shaped member. In addition, the material of the light-shielding film that faces the semiconductor layer can be blocked by the corners of the frame-like portion, and the material of the light-shielding film can be prevented from adhering to the semiconductor layer. be able to. Further, since the material of the light shielding film is emitted with high directivity, the light shielding film material is inappropriately attached to the semiconductor layer while appropriately forming the light shielding film on the inward side surface of the frame-like portion. It is suitable to prevent that .

In a preferred embodiment of the present invention, after the step of forming the semiconductor layer, there is a step of smoothing the stepped portion generated in the semiconductor layer. In the performing process . According to such a structure, the special process for forming the said frame-shaped part is unnecessary, and the said frame-shaped part can be formed easily, without reducing the efficiency of a manufacturing process .

In a preferred embodiment of the present invention, the step of performing the smoothing covered by the mask material a region including the semiconductor layer of the substrate is performed by performing an etch-back process to the mask material, the frame-shaped The portion is formed by leaving a portion surrounding the semiconductor layer in the mask material in the etch back process. The etch-back process is one method of flattening technology that is used, for example, in a laminated structure to reduce a step generated between each patterned layer. In general, an insulating film is applied so as to fill the step portion, and a predetermined portion of the insulating film is etched using a photoresist. The etch-back process has advantages such as being relatively simple as compared with other planarization techniques and being easy to cope with the miniaturization of an object. According to such a configuration, it is possible to finish the frame-like portion with a precise shape at a predetermined position by an etch-back process, and the semiconductor layer is appropriately formed using the inward side surface of the frame-like portion. It is suitable for forming the light-shielding film so as to surround the film .

In a preferred embodiment of the present invention, the mask material is SiO _2. Such a configuration is advantageous for finishing the frame-like portion into a desired shape. Since SiO ₂ is excellent in workability in etching, the frame-like portion can be formed so as to appropriately cover the semiconductor layer. In addition, it is preferable to control the etching rate in the etch back process so that the frame-shaped portion has an appropriate height with respect to the TFT element. However, when SiO ₂ is used, the height of the frame-shaped portion is relatively high. It can be finished accurately .

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

1 and 2 show an example of a liquid crystal display device manufactured by an example of a method for manufacturing a liquid crystal display device according to the present invention. The liquid crystal display device A includes a TFT substrate 1A and a counter substrate 1B, and a liquid crystal layer 7 interposed between these substrates. In FIG. 2, the interlayer insulating film 52 is omitted for convenience of explanation.

  The TFT substrate 1A is made of, for example, glass, and a plurality of TFT elements T are arranged in a matrix.

  The TFT element T is composed of a semiconductor layer 2, a gate insulating film 51, a gate electrode 31, a source electrode 32, and the like. The TFT element T is used for so-called switching of a plurality of pixels (not shown) arranged in a matrix in the liquid crystal display device A so as to switch the polarization state of the liquid crystal layer 7 corresponding to each pixel. .

The semiconductor layer 2 has a channel region 21, a source region 22, and a drain region 23, and is formed on the TFT substrate 1A. The semiconductor layer 2 is formed of polycrystalline silicon (hereinafter referred to as poly-Si). The channel region 21 is a region where a so-called channel is formed by an electric field from the gate electrode 31. The source region 22 and the drain region 23 are joined to the source electrode 32 and the drain 33, respectively. The semiconductor layer 2 may be formed of amorphous silicon (a-Si) instead of poly-Si.

The gate electrode 31 is for generating an electric field that acts on the channel region 21 and is formed of a metal thin film such as aluminum, tantalum, or tungsten. When the gate electrode 31 is in a high potential or low potential state, the pixel is switched. The gate insulating film 51 is for insulating the gate electrode 31 and the like from the semiconductor layer 2 and is formed of, for example, SiO ₂ or Si ₃ N ₄ .

  The source electrode 32 is supplied with a signal voltage from a source wiring (not shown), and is formed of a metal thin film, for example, like the gate electrode 31. The drain 33 is for supplying a signal voltage from the TFT element T to the pixel electrode 34, and is formed of, for example, the metal thin film described above.

The light-shielding portion 4 is composed of a frame-shaped portion 41 and a light-shielding film 42, and is provided so as to surround the semiconductor layer 2 of the TFT element T, the gate electrode 31, and the like, as clearly shown in FIG. The frame portion 41 is formed on the TFT substrate 1A using SiO ₂ . The frame-shaped portion 41 has a height at which the upper surface 41 b is sufficiently higher than the upper surface of the gate electrode 31. The light shielding film 42 is formed on the inward side surface 41 a and the upper surface 41 b of the frame-like portion 41, and serves to block light coming from the side toward the semiconductor layer 2. The light shielding film 42 is made of, for example, Ti or W. Ti or W is suitable for forming by sputtering or vapor deposition, as will be described later.

  The pixel electrode 34 is for applying a voltage in order to switch the polarization state of the liquid crystal layer 7 and is formed as a transparent electrode (ITO). A voltage corresponding to the display state of the pixel is supplied to the pixel electrode 34 via the drain 33 by the switching function of the TFT element T.

  The light distribution film 6A is for aligning liquid crystal molecules mixed in the liquid crystal material 71 of the liquid crystal layer 7 in one direction, and is subjected to a light distribution process such as a rubbing process. The light distribution film 6A is formed as a thin film using, for example, a polyimide resin.

  The counter substrate 1B is provided so as to face the TFT substrate 1A, and is made of, for example, glass. A common electrode 35 and a light distribution film 6B are formed on the lower surface of the counter substrate 1B.

  The liquid crystal layer 7 is a liquid crystal material 71 containing a liquid crystal such as a nematic liquid crystal in a space sealed by a seal material (not shown) in the region between the TFT substrate 1A and the counter substrate 1B. By changing the polarization state of a predetermined portion of the liquid crystal layer 7 according to the displayed image, the intensity of light transmitted through the liquid crystal layer 7 is adjusted, and the image display of the liquid crystal display device A is realized. The

  Next, a manufacturing method of the liquid crystal display device A will be described below with reference to the drawings.

  First, as shown in FIG. 3, a glass substrate material 1A 'is prepared, and a semiconductor layer 2 is formed on the substrate material 1A'. The semiconductor layer 2 is formed by, for example, forming a poly-Si film by CVD and patterning the film using photolithography.

After the semiconductor layer 2 is formed, a gate insulating film 51 is formed so as to cover the semiconductor layer 2 as shown in FIG. The gate insulating film 51 is formed by patterning after a film such as SiO ₂ or Si ₃ N ₄ is formed by CVD, for example. A gate electrode 31 is formed by forming a metal thin film such as aluminum, tantalum, or tungsten on the gate insulating film 51 by sputtering or the like and then performing patterning.

Next, etch back processing is performed for the purpose of smoothing the stepped portions generated in the semiconductor layer 2 and the gate electrode 31. In the present embodiment, a frame-like portion 41 that constitutes the light-shielding portion 4 is also formed during this etch-back process. First, as shown in FIG. 5, a SiO ₂ film 55 is formed so as to cover substantially the entire surface of the substrate material 1A ′ including the semiconductor layer 2, the gate electrode 31, and the like. Since the thickness of the film 55 is the height of the frame-like portion 41 to be formed later, the upper surface of the film 55 is sufficiently higher than the upper surface of the gate electrode 31. Next, as shown in FIG. 6, a shoulder portion 54 and a frame-like portion 41 are formed. The shoulder portion 54 and the frame-like portion 41 are formed by performing an etch back process on the film 55. As shown in FIG. 6A, the shoulder 54 has a gentle inclined surface from the upper surface edge of the gate electrode 31 toward the gate insulating film 51, and is excellent in FIG. 6B. As shown, the shape surrounds the gate electrode 31. As shown well in FIG. 6B, the frame-like portion 41 is separated from the semiconductor layer 2 and the gate electrode 31 in the plan view of the film 55 and leaves a frame-like portion surrounding them. To form. As clearly shown in FIG. 6A, the frame-like portion 41 has a height at which the upper surface 41 b is sufficiently higher than the upper surface of the gate electrode 31. If SiO ₂ is used as the material of the frame-shaped portion 41, it is suitable for finishing the frame-shaped portion 41 in a shape that appropriately covers the semiconductor layer 2 formed in a fine shape.

  After the frame portion 41 is formed, the light shielding film 42 is formed on the inward side surface 41 a and the upper surface 41 b of the frame portion 41. First, as shown in FIG. 7A, the right portion 41R of the frame-like portion 41 is subjected to a thin film forming method having directivity such as sputtering or vapor deposition using Ti or W. At this time, the thin film forming method is performed from a direction inclined with respect to the direction orthogonal to the substrate material 1A ′. In this embodiment, the thin film formation method is performed from a direction inclined by an angle θ with respect to the in-plane direction of the substrate material 1A ′. Do. The sputtering method or vapor deposition method radiates a metal material such as Ti or W toward a processing target with high directivity. In the present embodiment, the gate electrode 31 and the semiconductor layer 2 are shaded by the left portion 41L of the frame-like portion 41 from the direction in which Ti or W is radiated. It is possible to avoid the formation of a thin film of Ti or W on 2. On the other hand, since the inward side surface 41a of the right side portion 41R of the frame-like portion 41 does not become a shadow of the left side portion 41L of the frame-like portion 41, the light shielding film 42 can be appropriately formed. Further, as shown in FIG. 7B, the thin film forming method is performed from a direction inclined by an angle θ with respect to the in-plane direction of the substrate material 1A ′ from the side opposite to the direction shown in FIG. By applying, the light shielding film 42 is formed on the inward side surface 41a of the left side portion 41L of the frame-like portion 41. By performing such processing from four directions toward the frame-shaped portion 41, the light shielding film 42 can be formed on all the inward side surfaces 41a of the frame-shaped portion 41. If the light shielding film 42 is formed of Ti or W, it is suitable for avoiding problems such as the light shielding film 42 being unduly eroded in a process described later.

  Thereafter, the liquid crystal display device A is completed by a known process similar to the prior art. For example, after the implantation for forming the source region 22 and the drain region 23 is performed on the semiconductor layer 2, the interlayer insulating film 52 is formed so as to cover the entire surface of the substrate material 1A '. Further, a contact hole that leads to the source region 22 and the drain region 23 is formed at a predetermined position of the interlayer insulating film 52, and a metal film is patterned on the upper surface to form the source electrode 32 and the drain 33. Next, a protective film 53 is formed so as to cover them, and a pixel electrode 34 is formed thereon by patterning. Then, the TFT substrate 1A is obtained by forming the light distribution film 6A using a polyimide resin or the like. On the other hand, the counter electrode 1B is formed by laminating the common electrode 35 and the light distribution film 6B on the substrate material 1B 'such as glass. The TFT substrate 1A and the counter substrate 1B are opposed to each other, and a space between them is partitioned by providing a seal member (not shown) at the peripheral edge thereof, and the partition region is filled with a liquid crystal material 71 and sealed. A liquid crystal layer 7 is formed. Then, by appropriately providing a control IC (not shown) and a connection terminal portion (not shown), the liquid crystal surface device A can be obtained.

  Next, the operation of the liquid crystal display device A will be described.

  According to the present embodiment, even if the light incident on the interlayer insulating film 52 is repeatedly reflected in the interlayer insulating film 52 and travels toward the TFT element T in the far side of the TFT element T, such light is Since it is blocked by the light shielding film 42, it does not reach the semiconductor layer 2. Therefore, it is possible to prevent photocurrent from being generated due to photoelectric leakage effect due to light leakage from the side in the semiconductor layer 2, and the function of the TFT element T can be appropriately exhibited. Since the light shielding film 42 is formed on the inward side surface 41a of the frame-like portion 41 provided so as to surround the semiconductor layer 2 from four sides, it is suitable for shielding light from the four sides of the semiconductor layer 2.

  In the manufacture of the liquid crystal display device A, the light shielding film 42 is formed on the gate electrode 31 and the semiconductor layer 2 in order to form the light shielding film 42 by performing a thin film forming method from a direction inclined with respect to the thickness direction of the TFT substrate T. It is possible to prevent the metal material from adhering unreasonably, and there is no possibility that the function as the TFT element T will be hindered.

  In addition, according to the manufacturing method described above, the frame-like portion 41 can be formed in a batch in the etch-back process for smoothing the step portion between the semiconductor layer 2 and the gate electrode 31, so that the liquid crystal display The device A can be manufactured with the same efficiency as a conventional liquid crystal display device.

  As described above, according to the present embodiment, it is possible to appropriately shield light from the four sides of the semiconductor layer 2, but it is also possible to take measures against light shielding in the vertical direction of the semiconductor layer 2. For example, in the embodiment shown in FIG. 8, an upper light shielding film 43 and a lower light shielding film 44 are formed above and below the semiconductor layer 2. These may be formed of Ti or W like the light shielding film 42.

  The embodiment shown in FIG. 9 is different from the above-described embodiment in that the frame-shaped portion 43 itself has a light shielding property. The frame-shaped part 43 is formed of, for example, a resin mixed with a pigment. Also according to such an embodiment, the light shielding of the semiconductor layer 2 can be performed appropriately, the generation of the photocurrent can be suppressed, and the function of the TFT element T can be appropriately exhibited.

  The liquid crystal display device according to the present invention is not limited to the above-described embodiment. The specific configuration of each part of the liquid crystal display device according to the present invention can be varied in design in various ways.

  The frame portion is not limited to one having a rectangular outer shape, and may be, for example, a ring shape. The light shielding portion is constituted by a frame-shaped portion and a light shielding film formed thereon, which is preferable for improving light shielding properties and manufacturing efficiency, but the present invention is not limited to this, and is directed from the side of the semiconductor layer. Any material and shape that can appropriately block incoming light may be used. For example, an upright wall-shaped light shielding member may be provided.

  The structure of each part of the TFT element and other liquid crystal display devices in the above-described embodiments is an example thereof and is not limited thereto. The present invention can be applied to any liquid crystal display device having a semiconductor layer that produces a photoelectric conversion effect as a constituent member of a TFT element.

It is principal part sectional drawing which shows an example of the liquid crystal display device manufactured by an example of the manufacturing method of the liquid crystal display device which concerns on this invention. It is principal part sectional drawing in alignment with the II-II line of FIG. It is principal part sectional drawing which shows the manufacturing method of the liquid crystal display device which concerns on this invention. It is principal part sectional drawing which shows the manufacturing method of the liquid crystal display device which concerns on this invention. It is principal part sectional drawing which shows the manufacturing method of the liquid crystal display device which concerns on this invention. This figure (a) is principal part sectional drawing which shows the manufacturing method of the liquid crystal display device which concerns on this invention, This figure (b) is principal part top view which shows the manufacturing method of the liquid crystal display apparatus which concerns on this invention. is there. FIGS. 4A and 4B are cross-sectional views illustrating the main part of the method for manufacturing the liquid crystal display device according to the present invention. It is principal part sectional drawing which shows the other example of the liquid crystal display device manufactured by an example of the manufacturing method of the liquid crystal display device which concerns on this invention. It is principal part sectional drawing which shows the other example of the liquid crystal display device manufactured by an example of the manufacturing method of the liquid crystal display device which concerns on this invention. It is principal part sectional drawing which shows an example of the conventional liquid crystal display device.

A liquid crystal display device T TFT element 1A TFT substrate 1B counter substrate 2 semiconductor layer 4 light-shielding portion 7 liquid crystal layer 21 channel region 22 source region 23 drain region 31 gate electrode 32 source electrode 33 drain 34 pixel electrode 35 common electrode 41 frame-like portion 42 Light shielding film 43 Upper light shielding film 44 Lower light shielding film 51 Gate insulating film 52 Interlayer insulating film 53 Protective films 6A, 6B Light distribution film 71 Liquid crystal material

Claims (4)

A method for manufacturing a liquid crystal display device comprising a step of forming a semiconductor layer constituting a TFT element on a substrate,
After the step of forming the semiconductor layer, a step of forming a frame-like portion surrounding the semiconductor layer on the substrate;
By applying a sputtering method or a vapor deposition method as a thin film forming method having directivity along a direction inclined with respect to a direction orthogonal to the substrate from four directions surrounding the semiconductor layer, an inward side surface of the frame-shaped portion is formed. forming a light shielding film, and further comprising a method of manufacturing a liquid crystal display device. After the step of forming the semiconductor layer, the step of smoothing the stepped portion generated in the semiconductor layer,
The method for manufacturing a liquid crystal display device according to claim 1, wherein the frame portion is formed in the smoothing step . The step of performing the smoothing is performed by covering a region including the semiconductor layer of the substrate with a mask material, and performing an etch back process on the mask material,
The method of manufacturing a liquid crystal display device according to claim 2, wherein the frame-shaped portion is formed by leaving a portion surrounding the semiconductor layer in the mask material in the etch-back process . The mask material is SiO _2, The method according to claim 3.

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