JP2005051115A - Thin film transistor, manufacturing method thereof, optical functioning element, and manufacturing method of optical functioning element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin film transistor and an optical functioning element capable of preventing fracture caused by stress, and to provide the manufacturing method of the thin film transistor not damaging elements on a substrate on a formed side, and the manufacturing method of the optical functioning element not damaging an organic material thin film constituting the optical functioning element. <P>SOLUTION: The optical functioning element comprises on a substrate a light receiving layer containing an organic material, or a light emitting layer containing an organic material to which a thin film transistor is connected. The thin film transistor comprises a transparent gate electrode, a transparent gate insulating film in contact with the gate electrode, a transparent semiconductor layer facing the gate electrode putting the gate insulating film therebetween, a transparent source electrode electrically connected to the semiconductor layer, and a transparent drain electrode electrically connected to the semiconductor layer. There is formed with an organic material at least one among the substrate, gate electrode, semiconductor layer, source electrode, and drain electrode. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a thin film transistor, a method for manufacturing a thin film transistor, an optical functional element having a thin film transistor, and a method for manufacturing an optical functional element having a thin film transistor.

  At present, an optical functional element, for example, an imaging element for a color-compatible TV camera or the like, an incident light decomposing unit that decomposes incident light into, for example, three primary colors of blue, green, and red, and photoelectric conversion of the decomposed incident light One having a light receiving part is the mainstream.

  In such an image sensor, for example, a prism is used for the incident light decomposing unit, and the light beams for blue, green, and red, respectively, separated by the prism, are received by the three photoelectric conversion films of the light receiving unit. Many use so-called three-sheet image sensors. However, the conventional three-element image sensor has a problem that the image sensor becomes larger and the image sensor becomes heavier, making it difficult to reduce the size and weight of the image sensor.

  In view of this, it has been proposed to construct a single-plate stacked imaging device by stacking photoelectric conversion films having a wavelength selection function. (For example, refer to Patent Document 1). For example, among the incident light, a photoelectric conversion film having high sensitivity mainly in blue, a photoelectric conversion film mainly having high sensitivity in green, and a photoelectric conversion film mainly having high sensitivity in red are laminated to form a single-plate stacked imaging. An element is formed.

  FIG. 1 schematically shows a cross-sectional view of a multilayer imaging device 100, which is a configuration example of an optical functional device.

  Referring to FIG. 1, a first photoelectric conversion film 101A is formed on a substrate 101 so as to be sandwiched between electrodes 101a and 101b, thereby forming a first light receiving portion A. A substrate 102 is formed on the first light receiving portion A, and a second photoelectric conversion film 102A is formed on the substrate 102 so as to be sandwiched between the electrodes 102a and 102b. B is formed. A substrate 103 is formed on the second light receiving portion B, and a third photoelectric conversion film 103A is formed on the substrate 103 so as to be sandwiched between the electrodes 103a and 103b. B is formed.

  For example, the first photoelectric conversion film is a photoelectric conversion film mainly made of an organic material having photosensitivity in red, and the second photoelectric conversion film is a photoelectric conversion film mainly made of an organic material having photosensitivity in green. As the third photoelectric conversion film, a photoelectric conversion film made of an organic material mainly having blue photosensitivity is used.

  In this way, by forming a photoelectric conversion film using an organic material having a characteristic of absorbing only a specific wavelength region, a multilayer image sensor corresponding to the three primary colors (blue, green, red) is formed. Can be reduced in size and weight.

  In addition, the stacked image sensor has higher light utilization efficiency than, for example, an image sensor having a Bayer structure (see, for example, Non-Patent Document 1). For example, an image sensor having a three-layer photodiode (for example, Patent Document 2). Compared with reference), it has a high light receiving rate and high sensitivity.

  When actually controlling an optical functional element, for example, when an image signal is taken out from an imaging element, an element that reads an electric signal (charge) converted by a photoelectric conversion film made of an organic material is required. For example, a thin film transistor may be used as such a reading element.

For example, examples of the material used for the semiconductor layer of the thin film transistor include polycrystalline Si, single crystal Si, and polycrystalline cadmium selenium. In recent years, it has been proposed to use a transparent semiconductor material such as ITO (indium tin oxide film), ZnS, or ZnO in order to prevent the aperture ratio of the light receiving portion from decreasing. (For example, refer to Patent Document 3 to Patent Document 5).
JP 2002-217474 A USP 5965875 gazette JP-A-5-251705 JP-A-6-67187 JP 2003-86808 A Image Sensor Basics and Applications, Yuji Kiuchi, p145

  However, when a semiconductor layer is formed using a film made of these inorganic materials, there is a problem in that the photoelectric conversion film made of an organic material is damaged by heat applied in the process of forming the semiconductor layer.

  Furthermore, in the case of forming a thin film transistor, there is a step of forming a film made of an inorganic material such as an electrode or an insulating film in addition to the semiconductor layer, which damages the photoelectric conversion film made of an organic material due to heat. There are concerns.

  In addition, an inorganic material forming such a thin film transistor is a brittle material, and has a small fracture toughness value when compared with a photoelectric conversion film that is an organic material, and is easily damaged when stress is applied to the element. It was.

  Therefore, an object of the present invention is to provide a thin film transistor, a method for manufacturing a thin film transistor, an optical functional element, and a method for manufacturing an optical functional element, which have solved the above problems.

  A specific first object of the present invention is to provide a method of manufacturing a thin film transistor that does not damage the elements of the substrate on the side to be formed.

  A second object of the present invention is to provide a thin film transistor that prevents damage due to stress.

  A third object of the present invention is to provide a method for manufacturing an optical functional element that does not damage the organic material thin film constituting the optical functional element.

  A fourth problem of the present invention is to provide an optical functional element that prevents damage due to stress.

  In order to solve the above problems, the present invention provides a gate electrode, a gate insulating film in contact with the gate electrode, and a semiconductor facing the gate electrode with the gate insulating film interposed therebetween, formed on a transparent substrate A thin film transistor having a layer, a source electrode electrically connected to the semiconductor layer, and a drain electrode electrically connected to the semiconductor layer, wherein the gate electrode, the gate insulating film, the semiconductor layer, and the source electrode A thin film transistor is used in which the drain electrode is made of a transparent organic material.

  According to the present invention, since the thin film transistor is formed of a transparent material, it can be laminated with the light emitting layer and the light receiving layer, and the organic material having a soft and high fracture toughness value is used, so that the thin film transistor can be damaged. It becomes possible to prevent.

  Further, when the substrate is made of an organic material, the effect of preventing damage to the thin film transistor is further increased.

  It is preferable that a light-receiving layer containing an organic material or a light-emitting layer containing an organic material and the semiconductor layer be stacked, so that a stacked optical function element can be formed.

  In order to solve the above problems, the present invention provides a first step of forming a gate electrode on a transparent substrate, a second step of forming a gate insulating film in contact with the gate electrode, and the gate insulation. A method of manufacturing a thin film transistor, comprising: a third step of forming a semiconductor layer facing the gate electrode with a film interposed therebetween; and a fourth step of forming a source electrode and a drain electrode electrically connected to the semiconductor layer A method of manufacturing a thin film transistor is used, wherein the gate electrode, the gate insulating film, the semiconductor layer, the source electrode, and the drain electrode are formed of a transparent organic material.

  According to the present invention, since a transparent material is used when forming the thin film transistor, it is possible to stack the light emitting layer and the light receiving layer, and by using an organic material that is softer and has a high fracture toughness value, It is possible to prevent the thin film transistor from being damaged. In addition, since the temperature at which the organic material is formed is low, when the thin film transistor is formed, the element provided on the substrate side where the thin film transistor is formed is not damaged.

  In addition, when the substrate is made of an organic material, it is preferable that an element provided on the substrate side on which the thin film transistor is formed is not damaged when the thin film transistor is formed. In addition, the thin film transistor can be prevented from being damaged.

  In order to solve the above problems, the present invention provides an optical functional element in which a plurality of thin film transistors connected to a light receiving layer containing an organic material or a light emitting layer containing an organic material are stacked. The thin film transistor includes a transparent gate electrode formed on a transparent substrate, a transparent gate insulating film in contact with the gate electrode, a transparent semiconductor layer facing the gate electrode with the gate insulating film interposed therebetween, A transparent source electrode electrically connected to the semiconductor layer; and a transparent drain electrode electrically connected to the semiconductor layer, the gate electrode, the gate insulating film, the semiconductor layer, the source electrode, and the drain electrode. Among them, an optical functional element characterized in that at least one is formed of an organic material is used.

  According to the present invention, since the thin film transistor is formed of a transparent material, it is possible to stack the thin film transistor with the light emitting layer and the light receiving layer, and by using an organic material that is soft and has a high fracture toughness value, It is possible to prevent damage and form an optical functional element that is not easily damaged.

  Further, when the gate electrode, the gate insulating film, the semiconductor layer, the source electrode, and the drain electrode are formed of an organic material, it is possible to prevent the thin film transistor from being damaged and to form an optical functional element that is not easily damaged. Become.

  In addition, when the substrate is made of an organic material, the thin film transistor can be prevented from being damaged, and an optical functional element that is not easily damaged can be formed.

  In order to solve the above problems, the present invention provides a method for manufacturing an optical functional element in which a plurality of structures each having a thin film transistor connected to a light receiving layer containing an organic material or a light emitting layer containing an organic material are stacked. A first step of forming a transparent gate electrode on a transparent substrate; a second step of forming a transparent gate insulating film in contact with the gate electrode; and the gate electrode sandwiching the gate insulating film, A thin film transistor forming step including a third step of forming an opposing transparent semiconductor layer and a fourth step of forming a transparent source electrode and a drain electrode electrically connected to the semiconductor layer; and the light receiving layer Or a photoelectric layer forming step of forming a light emitting layer, and at least one of the gate electrode, the gate insulating film, the semiconductor layer, the source electrode, and the drain electrode is made of an organic material. The manufacturing method of the optical functional device, characterized in that made use.

  According to the present invention, since the organic material constituting the thin film transistor has a low temperature when formed, the light receiving layer containing the organic material or the light emitting layer containing the organic material is not damaged when the thin film transistor is formed. There is an effect.

  In addition, when the gate electrode, the gate insulating film, the semiconductor layer, the source electrode, and the drain electrode are formed of an organic material, the organic material is formed at a low temperature. The effect of not damaging the light receiving layer containing the material or the light emitting layer containing the organic material is increased, which is preferable.

  Further, when the substrate is made of an organic material, the light receiving layer containing the organic material or the light emitting layer containing the organic material is not damaged.

  Further, the thin film transistor forming step and the photoelectric layer forming step are repeated a plurality of times so that the temperature of the light receiving layer or the light emitting layer is maintained at 100 ° C. or lower in the thin film transistor forming step and the photoelectric layer forming step. If it makes it, there exists an effect which does not damage a light reception layer containing an organic material, or a light emitting layer containing an organic material.

  According to the present invention, it is possible to form a light transmission type thin film transistor without damaging an organic material film provided on the substrate side to be formed.

  Further, according to the present invention, when a thin film transistor is formed, a light emitting layer or a light receiving layer containing an organic material is not damaged, so that an optical functional element including the thin film transistor can be formed.

  In addition, according to the present invention, it is possible to provide a thin film transistor and an optical functional device having the thin film transistor that prevent damage due to stress or impact.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 2 schematically shows a cross-sectional view of a multilayer imaging element 10 which is an example of an optical functional element including a thin film transistor according to the first embodiment. Referring to FIG. 2, a thin film transistor (TFT) 20 is formed on a substrate 11, and a light receiving unit 30 is formed on the thin film transistor 20. A thin film transistor 40 formed on the substrate 41 is formed on the light receiving unit 30, and a light receiving unit 50 is formed on the thin film transistor 40. Further, a thin film transistor 60 formed on the substrate 61 is formed on the light receiving unit 50, a light receiving unit 70 is formed on the thin film transistor 60, and a plurality of thin film transistors and a plurality of light receiving units are stacked. It has become.

  The light receiving unit 30 includes a pixel electrode 31 and a counter electrode 33, and a light receiving layer 32 made of a photoelectric conversion film made of an organic material formed so as to be sandwiched between the pixel electrode 31 and the counter electrode 33. Similarly, the light receiving unit 50 includes a pixel electrode 51, a counter electrode 53, and a light receiving layer 52 including a photoelectric conversion film made of an organic material formed so as to be sandwiched between the pixel electrode 51 and the counter electrode 53. The unit 70 includes a pixel electrode 71 and a counter electrode 73, and a light receiving layer 72 made of a photoelectric conversion film of an organic material formed so as to be sandwiched between the pixel electrode 71 and the counter electrode 73.

  The light receiving layers 32, 52 and 72 according to the present embodiment are made of an organic material that has photosensitivity with respect to incident light having a specific wavelength and generates charges by photoelectric conversion. For example, the light receiving layer 32 has photosensitivity with respect to red of incident light, similarly, the light receiving layer 52 has light sensitivity with respect to green of incident light, and the light receiving layer 72 has light sensitivity with respect to blue of incident light. The organic material which has is used.

For this reason, it is possible to form a color-corresponding stacked image sensor in a structure in which the light receiving layers 32, 52 and 72 are stacked. Further, as elements for reading signal charges from the light receiving layers 32, 52, and 72, thin film transistors 20, 40, and 60 are connected through pixel electrodes 31, 51, and 71, respectively.
In addition, the thin film transistor has a structure laminated with the light receiving portion, and in order to improve the light receiving rate of the light receiving portion, the material constituting the thin film transistor, the pixel electrode and the counter electrode are transparent to visible light. Is used.

  Next, details of the thin film transistor of the optical functional element 10 will be described below. FIG. 3 is a cross-sectional view schematically showing details using the thin film transistor 20 as an example. However, in the figure, the same reference numerals are given to the parts described above, and the description will be omitted. Note that the transistor 20 and the transistors 50 and 70 have the same structure as the thin film transistor.

  Referring to FIG. 3, a gate electrode 12 is formed on a substrate 11, and a gate insulating film 13 is formed so as to cover the gate electrode 12. A semiconductor layer 14 is formed on the gate insulating film 13 so as to face the gate electrode 12 with the gate insulating film 13 interposed therebetween. Furthermore, a source electrode 15 and a drain electrode 16 that are electrically connected to the semiconductor layer 14 are formed on the semiconductor layer 14.

  The substrate 11, the gate electrode 12, the gate insulating film 13, the semiconductor layer 14, the source electrode 15 and the drain electrode 16 are made of a material that is transparent to visible light. Therefore, the light receiving rate is not lowered without blocking the light receiving part.

  In the thin film transistor 20 according to this embodiment, an organic material that can be formed at a low temperature is used as a material constituting the thin film transistor 20. Therefore, the light receiving layer made of an organic material of the multilayer imaging element 10 that is easily damaged by heating is not damaged. For example, when the thin film transistor 40 is formed on the light receiving layer 32 formed of a photoelectric conversion film made of an organic material, the light receiving layer 32 is damaged by heat if the temperature at which the thin film transistor 40 is formed is high. There is a fear.

  Conventionally, for example, when forming a ZnS film or a ZnO film on a semiconductor layer by using, for example, a MOCVD method (chemical vapor deposition method using an organic metal) or a sputtering method as a transparent material constituting a thin film transistor, Since the film forming temperature is as high as 200 ° C. or more, for example, there is a problem that the substrate temperature rises and the organic material of the optical functional element is damaged. For example, the organic material used for the light receiving layers 32, 52 and 72 has low heat resistance, and is decomposed or deteriorated in a temperature region exceeding 100 ° C., for example.

  Therefore, in this embodiment, for example, an organic semiconductor having a low temperature of 100 ° C. or lower is used for the semiconductor layer 14. For example, polyvinyl carbazole, polysilane, polythiophene, or the like can be used for the semiconductor layer 14.

  In this way, by forming the thin film transistor using an organic material, in the thin film transistor forming step, the temperature of an element formed on the substrate side on which the thin film transistor is formed, for example, a light receiving layer made of an organic material is The following can be maintained, and damage to the organic material can be prevented.

  In addition, organic materials are softer than inorganic materials such as ZnS and ZnO, and have a high fracture toughness value. Therefore, when stress is applied to the thin film transistor, the possibility that the thin film transistor is damaged can be reduced, and therefore, the optical functional element 10 having the thin film transistor can be hardly damaged.

  The thin film transistor 20 can also be formed by combining an organic material and an inorganic material as described above. For example, the insulating film 13 uses an insulating film such as sol-gel glass as the inorganic material. The gate electrode 12, the source electrode 15 and the drain electrode 16 can be made of, for example, ITO as an inorganic material.

  However, even when such an inorganic material is formed, it is necessary to keep the temperature of an element formed on the substrate side on which the thin film transistor is formed, for example, a light receiving layer made of an organic material, at 100 ° C. or lower. For example, since the sol-gel glass is formed at about room temperature, the light receiving layer is not damaged.

  Further, when forming electrodes made of ITO as the gate electrode 12, the source electrode 15 and the drain electrode 16, it is necessary to form them by a low temperature sputtering process in order to prevent an increase in the substrate temperature. Using a method such as RF-DC coupled magnetron sputtering or kinetic energy control sputtering, the temperature of the substrate 11 is set to 100 ° C. or less to form ITO. There is also a method of using RF plasma or DC plasma film formation that suppresses an increase in substrate temperature and suppresses RF power or DC power.

  Thus, in the case of this embodiment, in the thin film transistor forming step, the temperature of the light receiving layer made of, for example, an organic material formed on the substrate side on which the thin film transistor is formed is maintained at 100 ° C. or lower. It is possible to prevent the light receiving layer from being damaged.

  Further, by using an organic material for the insulating film 13, the gate electrode 12, the source electrode 15 and the drain electrode 16, the concern about the temperature rise in the thin film transistor forming process is eliminated, and the substrate side on which the thin film transistor is formed It is possible to prevent damage to an element formed in, for example, a light receiving layer made of an organic material.

  For example, a transparent resin such as polycarbonate and polyvinyl alcohol can be used for the insulating film 13, and PEDT / PSS (Polyethylene Dioxythiophene polystyrene sulphonate) can be used for the gate electrode 12, the source electrode 15, and the drain electrode 16.

  In addition, in this way, a portion where an organic material is used for the gate electrode 12, the gate insulating film 13, the semiconductor layer 14, the source electrode 15, and the drain electrode 16 forming the thin film transistor, that is, a portion formed of an organic material having a large fracture toughness value. When the stress is further applied to the thin film transistor, the possibility that the thin film transistor is damaged can be reduced. Therefore, the optical functional element 10 having the thin film transistor can be hardly damaged.

  In the case of the thin film transistor in the lowermost layer, that is, the thin film transistor 20, the substrate 11 can be made of glass because there is no light receiving layer made of an organic material under the thin film transistor 20. However, for example, in the case of the thin film transistors 40 and 60 in which an organic material is present in the lower layer, it is preferable to use an organic material that can lower the temperature at the time of formation, such as a polyimide resin.

  In addition, when the substrate 11 is made of a soft organic material having a high fracture toughness value, the possibility of destruction when the stress is applied to the thin film transistor 20 is further reduced, for example, a foldable thin film transistor, It is possible to form a foldable optical functional element having a thin film transistor.

  Next, an example of a manufacturing method for manufacturing the thin film transistor 20 will be described. 4A to 4D show a method of manufacturing the thin film transistor 20 in a step-by-step manner. However, in the figure, the same reference numerals are given to the parts described above, and a part of the description will be omitted.

  First, in the step shown in FIG. 4A, for example, an ITO film having a thickness of 50 nm is formed on the glass substrate 11 by the above-described low-temperature sputtering method, and a resist patterned by the photolithography method formed on the ITO film is masked. Then, the ITO film is etched to form the gate electrode 12.

  Next, in the step shown in FIG. 4B, 2 ml of a chloroform solution containing 20 mg of polycarbonate resin is prepared and applied by spin coating so as to cover the gate electrode 12 and the substrate 11 to form an insulating film 13 having a thickness of 100 nm. .

  Next, in the step shown in FIG. 4C, polydimethylsilane is deposited to a thickness of 100 nm by a vacuum vapor deposition method to form the semiconductor layer 14.

  Next, in the step shown in FIG. 4D, an ITO film is formed to a thickness of 50 nm by a low-temperature sputtering method using a mask, a source electrode 15 and a drain electrode 16 are formed, and a transparent thin film transistor that transmits visible light. Form.

  When the thin film transistor 20 is actually incorporated into the optical functional element, the pattern shape of the gate electrode 15 and the drain electrode 16 is changed as necessary, and a protective insulating film is formed on the gate electrode 15 and the drain electrode 16. May form.

  Further, the second embodiment can be modified as in the third embodiment described below, and will be described based on FIGS. 4A to 4D as in the second embodiment. However, in the figure, the same reference numerals are given to the parts described above, and a part of the description will be omitted.

  The process shown in FIG. 4A is the same as that in the second embodiment.

  Next, in the step shown in FIG. 4B, an insulating film 13 made of polyimide is formed to a thickness of 100 nm by condensation polymerization of aromatic tetracarboxylic dianhydride and diamine.

  Next, in the step shown in FIG. 4C, 2 ml of a chloroform solution containing 30 mg of polyvinyl carbazole is prepared and applied by spin coating to form a semiconductor layer 14 having a thickness of 100 nm. The process shown in FIG. 4D is the same as that in the second embodiment.

  For example, an organic solvent is used in the process shown in FIG. 4B of Example 2 and the process shown in FIG. 4C of Example 3. In order to remove such an organic solvent from the formed film, for example, it is preferable to add a treatment for holding the substrate at about 60 ° C. to 80 ° C. or a treatment for holding the substrate under reduced pressure, as necessary.

  Further, in Example 2 and Example 3, the substrate 11 made of glass is used. For example, when forming the upper layer, that is, the thin film transistors 40 and 60 shown in FIG. 2, the substrate 11 is formed at a low temperature (100 ° C. or less). It is preferable to use a substrate made of an organic material that can be used.

  For example, by forming the substrate 11 using the organic material, the manufacturing methods shown in Example 2 and Example 3 can be applied to a method for forming an upper-layer thin film transistor.

  Next, Examples 4 to 5 show examples of forming a thin film transistor by forming a substrate with an organic material. Such a method of manufacturing a thin film transistor can be applied to the upper layer thin film transistor, and can also be used to manufacture the lower layer, that is, the thin film transistor 20.

  The fourth embodiment is a method for manufacturing a thin film transistor including a method for forming a substrate made of an organic material, and will be described based on FIGS. 4A to 4D as in the case of the second to third embodiments. To do. However, in the figure, the same reference numerals are given to the parts described above, and a part of the description will be omitted.

  First, in the step shown in FIG. 4A, a substrate 11 made of polyimide is formed by condensation polymerization of an aromatic tetracarboxylic dianhydride and a diamine. Next, an ITO film having a thickness of 50 nm is formed on the substrate 11 by the above-described low-temperature sputtering method, and the ITO film is etched by using a resist patterned by the photolithography method formed on the ITO film as a mask. The electrode 12 is formed.

  The steps shown in FIGS. 4B to 4D are the same as those shown in the second embodiment.

  Further, the fourth embodiment can be modified as in the fifth embodiment described below, and will be described based on FIGS. 4A to 4D as in the case of the fourth embodiment. However, in the figure, the same reference numerals are given to the parts described above, and a part of the description will be omitted.

  First, in the step shown in FIG. 4A, a substrate 11 made of polyimide is formed by condensation polymerization of an aromatic tetracarboxylic dianhydride and a diamine. Next, a PEDT / PSS aqueous solution is sprayed onto the substrate 11 by an ink jet method to form a patterned gate electrode 12 made of PEDT / PSS.

  The steps shown in FIGS. 4B to 4C are the same as those in the third embodiment.

  Next, in the step shown in FIG. 4D, a PEDT / PSS aqueous solution is sprayed onto the semiconductor layer 14 by an ink jet method to form the patterned source electrode 15 and drain electrode 16 made of PEDT / PSS.

  Further, in any of Examples 2 to 5, in the thin film transistor manufacturing process, the substrate temperature is suppressed to 100 ° C. or lower, and the stacked organic material, for example, the light receiving portion is not damaged.

The thin film transistors manufactured using Examples 2 to 5 all have a visible light transmittance of 80% or more, and an ON / OFF ratio of current of about 10 ⁵ . Good characteristics as a thin film transistor were obtained.

  In this manner, thin film transistors can be formed by combining materials as necessary. In the case of Examples 4 to 5, since both the substrate and the thin film transistor are formed of an organic material having a high fracture toughness value, it is possible to realize a light transmissive thin film transistor that can be folded. It becomes. Moreover, when stress is applied from the outside, the effect which resists damage is produced.

  Therefore, for example, it is possible to construct a foldable optical functional element in combination with a foldable light receiving section or light emitting section, which is convenient to carry and has a low possibility of breakage and is resistant to impact. It is possible to achieve the effect.

  Next, details of the optical functional element 10 including the thin film transistors shown in the first to fifth embodiments will be described with reference to FIGS. FIG. 5 is a diagram schematically showing details of a cross section of the image sensor 10 which is an example of an optical functional device including a thin film transistor, and FIG. 6 is a diagram schematically showing a plan view thereof. Is a diagram showing an equivalent circuit thereof. However, in the figure, the same reference numerals are given to the parts described above, and the description will be omitted.

  Referring to FIGS. 5 to 7, the light receiving unit 30 having a light receiving layer 32 made of an organic material is formed on the thin film transistor 20 formed on the substrate 11. The light receiving layer 32 is sandwiched between the pixel electrode 31 and the counter electrode 33, and the light receiving layer 32 is electrically connected to the drain electrode 16 via the pixel electrode 31. Yes.

  A part of the source electrode 15 and the drain electrode 16 is covered with a protective insulating film 17 to be protected and insulated. If necessary, a signal storage capacitor electrode 18 may be formed on the substrate 11.

  The substrate 41 is formed on the light receiving unit 30, and the thin film transistor 40 is formed on the substrate 41. The thin film transistor 40 has a structure similar to that of the thin film transistor 20, and includes a gate electrode 42, an insulating film 43, a semiconductor layer 44, a source electrode 45, and a drain electrode 46, and the light receiving layer 52 includes the pixel. The electrode 51 is electrically connected to the drain electrode 46.

  A part of the source electrode 45 and the drain electrode 46 is covered with a protective insulating film 47 to be protected and insulated. Further, if necessary, a signal storage capacitor electrode 48 may be formed on the substrate 41.

  The substrate 61 is formed on the light receiving unit 50, and the thin film transistor 60 is formed on the substrate 61. The thin film transistor 60 has a structure similar to that of the thin film transistor 20, and includes a gate electrode 62, an insulating film 63, a semiconductor layer 64, a source electrode 65, and a drain electrode 66, and the light receiving layer 72 includes the pixel. The electrode 71 is electrically connected to the drain electrode 66.

  A part of the source electrode 65 and the drain electrode 66 is covered with a protective insulating film 67 to be protected and insulated. Further, if necessary, a signal storage capacitor electrode 68 may be formed on the substrate 71.

  As shown in FIG. 7, the optical functional element 10 is controlled by a driving circuit system such as a general source driver and gate driver. In FIG. 7, a power supply (not shown) is connected to the end of the light receiving unit 30, that is, the counter electrode 33.

  In this manner, the color-capable stacked imaging element 10 is configured by stacking the light receiving portion having the light receiving layer made of the thin film transistor and the organic material.

  Moreover, the visible light transmittance of a material generally used for a transparent electrode or a transparent semiconductor layer is not 100%, and for example, in the case of ITO or PEDT / PSS, it is about 90%. For this reason, for example, incident light that reaches the light receiving layer 32 or 52 is attenuated, so that sensitivity correction between the light receiving layers 72, 52, and 32 is required.

  Further, when the pixel electrodes 31, 51 and 71 and the counter electrodes 33, 53 and 73 are formed of, for example, an ITO film, the light receiving layer made of an organic material is damaged by using the low temperature sputtering method as described above. It is necessary not to give.

  Further, when the pixel electrodes 31, 51 and 71 and the counter electrodes 33, 53 and 73 are formed of an organic material having a large fracture toughness value, the thin film transistor 20 formed of an organic material having a high fracture toughness value, By combining with 40 and 60, it is possible to constitute an optical functional element, for example, an imaging element, which is less likely to be damaged by external stress.

  For this reason, damage to the optical functional element is prevented in the manufacturing process of the optical functional element, the yield of the manufacturing process is improved, and the possibility of damage when the optical functional element is carried is reduced, which is strong against impact. An element can be realized. Further, the optical functional element can be folded, and an element that is convenient for carrying can be formed. This is a particularly effective feature in the case of a light emitting element described later.

  Next, a method for manufacturing the multilayer optical functional element 10 including the method for manufacturing the thin film transistor 10 will be described with reference to FIGS. 8 (A) to 8 (D) and FIGS. 9 (E) to 9 (F). As a method for forming the thin film transistor, for example, the methods shown in Examples 2 to 5 can be used.

  First, in the step shown in FIG. 8A, for example, an ITO film is formed on the glass substrate 11 by the above-described low-temperature sputtering method, and a resist patterned by the photolithography method formed on the ITO film is masked. Then, the ITO film is etched to form the gate electrode 12 and the signal storage capacitor electrode 18.

  Next, in the process shown in FIG. 8B, an insulating film 13 made of polyimide is formed to 100 nm by condensation polymerization of aromatic tetracarboxylic dianhydride and diamine.

  Next, in the step shown in FIG. 9C, 2 ml of a chloroform solution containing 30 mg of polyvinylcarbazole is prepared and applied by a spin coating method to form the semiconductor layer 14 with a thickness of 100 nm.

  Next, in the step shown in FIG. 8D, an ITO film is formed to a thickness of 50 nm by a low-temperature sputtering method using a mask, the source electrode 15 and the drain electrode 16 are formed, and the source electrode 15 and the drain electrode 16 are further formed. A protective insulating film 17 made of polyimide is formed so as to cover a part of the film.

  Next, in the step shown in FIG. 9E, an ITO film is deposited to a thickness of 50 nm by a low-temperature sputtering method using a mask to form a pixel electrode 31.

  Next, on the pixel electrode 31, for example, zinc phthalocyanine, which is an organic material having sensitivity only to red light, is deposited by vacuum vapor deposition so that the film thickness becomes 200 nm, and the photoelectric conversion film having sensitivity to red is used. The light receiving layer 32 is formed. Further, an ITO film is deposited on the light receiving layer 32 by 50 nm by a low-temperature sputtering method using a mask, the counter electrode 33 is formed, and the light receiving portion 30 is formed.

  Next, in the step shown in FIG. 9F, a substrate 41 made of polyimide is formed to 100 nm on the counter electrode 31 by condensation polymerization of aromatic tetracarboxylic dianhydride and diamine. Next, an ITO film having a thickness of 50 nm is formed on the substrate 41 by the low-temperature sputtering method, and the ITO film is etched by using a resist patterned by the photolithography method formed on the ITO film as a mask. The electrode 42 and the signal storage capacitor electrode 48 are formed.

  Thereafter, similarly to the steps shown in FIGS. 8B to 8D and FIG. 9E, the insulating film 43, the semiconductor layer 44, the source electrode 45, the drain electrode 46, the protective insulating film 47, the pixel electrode 51, the light receiving layer 52 and the counter electrode 53 are formed.

  When the light receiving layer 52 is formed, a photoelectric conversion film having an organic material sensitive only to green light, for example, a perylene pigment deposited by vacuum evaporation so that the film thickness becomes 200 nm, and having a sensitivity to green. A light receiving layer 52 made of is formed. In this way, the light receiving unit 50 is formed.

  Further, on the light receiving portion 50, the substrate 71, the gate electrode 62, the storage capacitor electrode 68, the insulating film 63, the semiconductor layer 64, the source electrode 65, and the drain electrode 66 are formed in the same manner as when the light receiving portion 50 is formed. Then, the protective insulating film 67, the pixel electrode 71, the light receiving layer 72, and the counter electrode 73 are formed.

  In the case of forming the light receiving layer 72, for example, porphyrin, which is an organic material having sensitivity only to blue light, is deposited by vacuum evaporation so that the film thickness is 200 nm, and the photoelectric conversion film having sensitivity to blue is used. A light receiving layer 72 was formed. In this way, the light receiving unit 70 is formed, and the multilayer imaging element 10 shown in FIG. 5 is formed.

  Also, in the process of forming the light emitting portion shown in FIGS. 9E to 9F, the temperature of the light receiving layer made of an organic material is set to 100 ° C. or less, and the organic material of the light receiving layer is damaged. Is prevented.

  Moreover, Example 7 can also be changed like Example 8 shown below, and similarly to the case of Example 8, FIGS. 8A to 8D and FIGS. A description will be given based on B). However, in the figure, the same reference numerals are given to the parts described above, and a part of the description will be omitted.

  First, in the step shown in FIG. 8A, a substrate 11 made of polyimide is formed by condensation polymerization of an aromatic tetracarboxylic dianhydride and a diamine. Next, the PEDT / PSS aqueous solution is sprayed onto the substrate 11 by an ink jet method to form the gate electrode 12 and the signal storage capacitor electrode 18 made of patterned PEDT / PSS.

  Next, in the step shown in FIG. 8B, an insulating film 13 made of polyimide is formed to 100 nm by condensation polymerization of aromatic tetracarboxylic dianhydride and diamine.

  Next, in the step shown in FIG. 8C, 2 ml of a chloroform solution containing 30 mg of polyvinylcarbazole is prepared and applied by a spin coating method to form the semiconductor layer 14 with a thickness of 100 nm.

  Next, in the step shown in FIG. 8D, a source electrode 15 and a drain electrode 16 made of patterned PEDT / PSS are formed by spraying a PEDT / PSS aqueous solution onto the semiconductor layer 14 by an inkjet method, Further, a protective insulating film 17 made of polyimide is formed so as to cover part of the source electrode 15 and the drain electrode 16.

  Next, in a step shown in FIG. 9E, a PEDT / PSS aqueous solution is sprayed by an ink jet method to form a pixel electrode 31 having a thickness of 50 nm and made of patterned PEDT / PSS.

  Next, on the pixel electrode 31, for example, zinc phthalocyanine, which is an organic material having sensitivity only to red light, is deposited by vacuum vapor deposition so that the film thickness becomes 200 nm, and the photoelectric conversion film having sensitivity to red is used. The light receiving layer 32 is formed. Further, a counter electrode having a film thickness of 50 nm made of PEDT / PSS is deposited on the light receiving layer 32 by spin coating to form the light receiving unit 30.

  Next, in the step shown in FIG. 9F, in the same manner as the step shown in FIG. 9E, the substrate 41, the gate electrode 42, the signal storage capacitor electrode 48, and the insulating film 43 are formed on the light receiving portion 30. The semiconductor layer 44, the source electrode 45, the drain electrode 46, the protective insulating film 47, the pixel electrode 51, the light receiving layer 52, and the counter electrode 53 are formed.

  When the light receiving layer 52 is formed, a photoelectric conversion film having an organic material sensitive only to green light, for example, a perylene pigment deposited by vacuum evaporation so that the film thickness becomes 200 nm, and having a sensitivity to green. A light receiving layer 52 made of is formed. In this way, the light receiving unit 50 is formed.

  Further, on the light receiving portion 50, the substrate 71, the gate electrode 62, the signal storage capacitor electrode 68, the insulating film 63, the semiconductor layer 64, the source electrode 65, and the drain electrode 66 are formed in the same manner as the step of forming the light receiving portion 50. Then, the protective insulating film 67, the pixel electrode 71, the light receiving layer 72, and the counter electrode 73 are formed.

  In the case of forming the light receiving layer 72, for example, porphyrin, which is an organic material having sensitivity only to blue light, is deposited by vacuum evaporation so that the film thickness is 200 nm, and the photoelectric conversion film having sensitivity to blue is used. A light receiving layer 72 was formed. In this way, the light receiving unit 70 is formed, and the stacked image sensor shown in FIG. 5 is formed.

  Also, in the process of forming the light emitting portion shown in FIGS. 9E to 9F, the temperature of the light receiving layer made of an organic material is set to 100 ° C. or less, and the organic material of the light receiving layer is damaged. Is prevented.

  In the case of this embodiment, the pixel electrodes 31, 51 and 71 and the counter electrodes 33, 53 and 73 are formed of an organic material having a large fracture toughness value, and are formed of an organic material having a large fracture toughness value. In combination with the thin film transistors 20, 40 and 60, it is possible to constitute an optical functional element, for example, an imaging element, which is less likely to be damaged by an external stress.

  For this reason, damage to the optical functional element is prevented in the manufacturing process of the optical functional element, the yield of the manufacturing process is improved, and the possibility of damage when the optical functional element is carried is reduced, which is strong against impact. An element can be realized. Furthermore, the optical functional element can be folded, and an element convenient for carrying can be formed.

  In any case, no damage was observed in the light receiving unit 30 and the light receiving unit 50 in the multilayer imaging device produced by the method shown in Example 8 and Example 9. In addition, when the multilayer image sensor was irradiated with white light from above (the light receiving unit 70 side) and from below (the light receiving unit 30 side), a signal current was observed from each of the light receiving units 30, 50, and 70. .

  Moreover, although Example 1-Example 8 described the case of an image pick-up element mainly as an example of an optical function element, this invention is not limited to this. The present invention can be similarly applied to the case of forming another optical functional element, for example, a light emitting element including a thin film transistor, and the same effect as that in the case of forming the imaging element shown in Embodiments 1 to 8 can be obtained. It is possible.

  FIGS. 10A to 10B schematically show cross-sectional views of a light emitting unit 200 and a light emitting unit 300 having a light emitting layer composed of an organic EL (electroluminescence) layer according to a tenth embodiment of the present invention. Show.

  First, referring to FIG. 10A, the light emitting unit 200 includes a light emitting layer 202 made of an organic EL layer, an anode 201 formed on the first surface of the light emitting layer 202, and a first layer of the light emitting layer 202. The cathode 203 formed on the second surface is provided. The light emitting unit 202 has a structure in which the light emitting layer 202 emits light when a voltage is applied between the anode 201 and the cathode 203.

  For this reason, for example, in the multilayer imaging device 10 shown in FIG. 5, if the light emitting unit 200 is replaced in place of the light receiving unit, a light emitting device having an organic EL layer can be formed.

  For example, when red, green, and blue light emitting portions are formed in the portions corresponding to the light receiving portions 30, 50, and 70, respectively, it is possible to form color-compatible light emitting elements. In that case, the control circuit is changed as necessary, but a general control circuit for a light-emitting element can be used.

  In addition, the light emitting element 200 can have a multilayer structure by forming a thin film between the cathode and the light emitting layer or between the anode and the light emitting layer as necessary, for example. You may apply to this invention. As described above, the structure of the light emitting unit can be arbitrarily changed.

  FIG. 10B illustrates an example of a light-emitting portion 300 that is a modified example of FIG. Referring to FIG. 10B, the light emitting unit 300 includes an anode 301, a buffer layer 302 formed on the anode 301, a hole transport layer 303 formed on the buffer layer 302, and the hole transport. The light-emitting layer 304 includes an organic EL layer formed on the layer 303, the electron-transport layer 305 formed on the light-emitting layer 304, and the cathode 306 formed on the electron-transport layer 305. As described above, when the multilayered light emitting unit 300 is used, the same effect as that in the case of forming the multilayer imaging element 10 described in the first to eighth examples is used together with the case where the light emitting unit 200 is used. Can be obtained.

  For example, when the light emitting unit 200 or the light emitting unit 300 is formed of an organic material having a large fracture toughness value including an anode and a cathode, a light emitting element that can be bent can be realized.

  Further, since the thin film transistor is transparent, it is possible to correspond to both a so-called top emission type and bottom emission type.

  Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the specific embodiments described above, and various modifications and changes can be made within the scope described in the claims.

  According to the present invention, it is possible to form a light transmission type thin film transistor without damaging an organic material film provided on the substrate side to be formed.

  Further, according to the present invention, when a thin film transistor is formed, a light emitting layer or a light receiving layer containing an organic material is not damaged, so that an optical functional element including the thin film transistor can be formed.

  In addition, according to the present invention, it is possible to provide a thin film transistor and an optical functional device having the thin film transistor that prevent damage due to stress or impact.

It is a figure which shows the structure of the image pick-up element which is an example of the conventional optical function element. It is sectional drawing which showed typically the structure of the multilayer image pick-up element which is an optical functional element by Example 1 of this invention. It is sectional drawing which shows the structure of the thin-film transistor used for the laminated type image pick-up element of FIG. (A)-(D) are figures which show the manufacturing method of the thin-film transistor of FIG. FIG. 3 is a cross-sectional view schematically showing details of the multilayer image sensor of FIG. 2. FIG. 6 is a plan view of the multilayer image sensor of FIG. 5. FIG. 6 is an equivalent circuit diagram of the multilayer image sensor of FIG. 5. (A)-(D) are figures (the 1) which show the manufacturing method of the multilayer image pick-up element of FIG. (E)-(F) is a figure (the 2) which shows the manufacturing method of the multilayer image pick-up element of FIG. (A)-(B) is sectional drawing which showed the light emission part by Example 9 of this invention.

Explanation of symbols

10, 100 Multilayer imaging device 11, 41, 61, 101, 102, 103 Substrate 12, 42, 72 Gate electrode 13, 43, 63 Insulating film 14, 44, 64 Semiconductor layer 15, 45, 65 Source electrode 16, 46 , 66 Drain electrode 17, 47, 67 Protective insulating film 18, 48, 68 Signal storage capacitor electrode 20, 40, 60 Thin film transistor 30, 50, 70, A, B, C Light receiving part 31, 51, 71 Pixel electrode 32, 52 , 72 Light receiving layer 33, 53, 73 Counter electrode 101a, 101b, 102a, 102b, 103a, 103b Electrode 101A, 102A, 103A Photoelectric conversion film 200, 300 Light emitting part 201, 301 Anode 202, 304 Light emitting layer 203, 306 Cathode 302 Buffer layer 303 Hole transport layer 305 Electron transport layer

Claims (12)

A gate electrode formed on a transparent substrate;
A gate insulating film in contact with the gate electrode;
A semiconductor layer facing the gate electrode across the gate insulating film;
A source electrode electrically connected to the semiconductor layer;
A thin film transistor having a drain electrode electrically connected to the semiconductor layer,
A thin film transistor, wherein the gate electrode, the gate insulating film, the semiconductor layer, the source electrode and the drain electrode are made of a transparent organic material.   2. The thin film transistor according to claim 1, wherein the substrate is made of an organic material.   3. The thin film transistor according to claim 1, wherein a light receiving layer containing an organic material or a light emitting layer containing an organic material and the semiconductor layer are laminated. A first step of forming a gate electrode on a transparent substrate;
A second step of forming a gate insulating film in contact with the gate electrode;
A third step of forming a semiconductor layer facing the gate electrode with the gate insulating film interposed therebetween;
And a fourth step of forming a source electrode and a drain electrode that are electrically connected to the semiconductor layer,
A method of manufacturing a thin film transistor, wherein the gate electrode, gate insulating film, semiconductor layer, source electrode, and drain electrode are formed of a transparent organic material.   5. The method of manufacturing a thin film transistor according to claim 4, wherein the substrate is made of an organic material. An optical functional element in which a light receiving layer containing an organic material or a light emitting layer containing an organic material is laminated with a plurality of structures in which thin film transistors are connected,
The thin film transistor
A transparent gate electrode formed on a transparent substrate;
A transparent gate insulating film in contact with the gate electrode;
A transparent semiconductor layer facing the gate electrode across the gate insulating film;
A transparent source electrode electrically connected to the semiconductor layer;
A transparent drain electrode electrically connected to the semiconductor layer,
At least one of the gate electrode, the gate insulating film, the semiconductor layer, the source electrode, and the drain electrode is formed of an organic material.   The optical functional element according to claim 6, wherein the gate electrode, the gate insulating film, the semiconductor layer, the source electrode, and the drain electrode are formed of an organic material.   The optical functional element according to claim 7, wherein the substrate is made of an organic material. A method of manufacturing an optical functional element in which a light receiving layer containing an organic material or a light emitting layer containing an organic material is laminated with a plurality of structures in which thin film transistors are connected,
A first step of forming a transparent gate electrode on a transparent substrate;
A second step of forming a transparent gate insulating film in contact with the gate electrode;
A third step of forming a transparent semiconductor layer facing the gate electrode across the gate insulating film;
A thin film transistor forming step including a fourth step of forming a transparent source electrode and a drain electrode electrically connected to the semiconductor layer;
A photoelectric layer forming step of forming the light receiving layer or the light emitting layer, wherein at least one of the gate electrode, the gate insulating film, the semiconductor layer, the source electrode, and the drain electrode is formed of an organic material. A method for manufacturing an optical functional element.   The method for manufacturing an optical functional element according to claim 9, wherein the gate electrode, the gate insulating film, the semiconductor layer, the source electrode, and the drain electrode are formed of an organic material.   The method for manufacturing an optical functional element according to claim 10, wherein the substrate is formed of an organic material. The thin film transistor forming step and the photoelectric layer forming step are repeated a plurality of times, and the temperature of the light receiving layer or the light emitting layer is maintained at 100 ° C. or lower in the thin film transistor forming step and the photoelectric layer forming step. The method for manufacturing an optical functional element according to claim 9, wherein the optical functional element is manufactured.

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