JP2006253380A - Organic ferroelectric memory and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic ferroelectric memory in which a manufacturing method is facilitated while enhancing the degree of freedom, and to provide its manufacturing method. <P>SOLUTION: The manufacturing method of an organic ferroelectric memory comprises (a) a step for forming an organic thin film transistor 120 having a source electrode 110, a drain electrode 112, an organic semiconductor layer 114, a gate insulation layer 116 and a gate electrode 128 above a substrate 100, (b) a step for forming a first contact layer 124 connected electrically with the organic thin film transistor 120 while penetrating an interlayer insulation layer 122, and a second contact layer 126 connected electrically with the organic thin film transistor 120 while penetrating the interlayer insulation layer 122, (c) a step for forming a wiring layer 130 connected electrically with the first contact layer 124, and (d) a step for forming an organic ferroelectric capacitor 140 connected electrically with the second contact layer 126 and having a lower electrode 142, an organic ferroelectric layer 144 and an upper electrode 146. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic ferroelectric memory and a method for manufacturing the same.

As a ferroelectric memory, a structure of a ferroelectric capacitor including an inorganic ferroelectric layer such as a PZT system or an SBT system is well known. The inorganic ferroelectric layer needs to be annealed at a high temperature of 600 ° C. or higher when it is formed. For this reason, the substrate for forming the ferroelectric capacitor is limited to one having heat resistance, and it is impossible to use a flexible substrate such as a glass substrate or plastic as the substrate. Furthermore, since the inorganic ferroelectric layer contains heavy metals such as Pb and Bi, it is harmful to the environment and its handling is complicated.
Japanese Patent Application Laid-Open No. 5-89661

  One of the objects of the present invention is to provide an organic ferroelectric memory and a method of manufacturing the same that can facilitate the manufacturing process and improve design flexibility.

(1) A method for manufacturing an organic ferroelectric memory according to the present invention includes:
An organic ferroelectric memory manufacturing method comprising:
(A) forming an organic thin film transistor having a source electrode, a drain electrode, an organic semiconductor layer, a gate insulating layer and a gate electrode above the substrate;
(B) forming an interlayer insulating layer above the organic thin film transistor;
(C) forming a first contact layer electrically connected to the organic thin film transistor in the interlayer insulating layer and a second contact layer electrically connected to the organic thin film transistor in the interlayer insulating layer;
(D) forming a wiring layer electrically connected to the first contact layer;
(E) forming an organic ferroelectric capacitor electrically connected to the second contact layer and having a lower electrode, an organic ferroelectric layer and an upper electrode;
including. According to the present invention, since an organic ferroelectric capacitor including an organic ferroelectric layer and an organic thin film transistor including an organic semiconductor layer are formed, a low-temperature process of, for example, 150 ° C. or less as a whole becomes possible. Therefore, the restriction on the heat resistance of the substrate is relaxed, and the degree of freedom of selection of the substrate is improved. In addition, since the organic ferroelectric material can be processed with low energy, the manufacturing process can be facilitated. Furthermore, there is no problem of environmental load due to heavy metals, it can be easily disposed of and it is easy to handle.
(2) In this method of manufacturing an organic ferroelectric memory,
The steps (a) to (e) may be performed by a liquid phase process. Thereby, an inexpensive and easy manufacturing process can be realized.
(3) In this method of manufacturing an organic ferroelectric memory,
In the step (a), at least one of the source electrode, the drain electrode, the organic semiconductor layer, the gate insulating layer, and the gate electrode may be formed in a predetermined pattern by a droplet discharge method. Thereby, since a pattern can be directly formed, the manufacturing process can be facilitated.
(4) In this method of manufacturing an organic ferroelectric memory,
In the step (a), the organic semiconductor layer may be formed of a fluorene-thiophene copolymer.
(5) In this method of manufacturing an organic ferroelectric memory,
In the step (e), at least one of the lower electrode, the organic ferroelectric layer, and the upper electrode may be formed in a predetermined pattern by a droplet discharge method. Thereby, since a pattern can be directly formed, the manufacturing process can be facilitated.
(6) In this method of manufacturing an organic ferroelectric memory,
In the step (e), the organic ferroelectric layer is formed by ashing the organic ferroelectric layer using the upper electrode having the predetermined pattern as a mask by forming the upper electrode to have a predetermined pattern. The layer may be patterned. According to this, by using the upper electrode as a mask, it is not necessary to form a mask for patterning the organic ferroelectric layer, and the manufacturing process can be facilitated.
(7) In the method of manufacturing the organic ferroelectric memory,
In the step (e), at least one of the lower electrode and the upper electrode may be formed of a conductive organic material. According to this, the hysteresis characteristic of the organic ferroelectric capacitor is improved.
(8) In this method of manufacturing an organic ferroelectric memory,
In the step (e), the organic ferroelectric layer is made of poly (vinylidene fluoride / trifluoroethylene), polyvinylidene fluoride, (vinylidene fluoride / trifluoroethylene) co-oligomer, vinylidene fluoride oligomer, and odd-number nylon. You may form by either.
(9) In this method of manufacturing an organic ferroelectric memory,
The substrate may be an organic substrate.
(10) In this method of manufacturing an organic ferroelectric memory,
After the step (d), further comprising forming an intermediate insulating layer above the wiring layer;
In the step (e), the organic ferroelectric capacitor may be formed above the intermediate insulating layer. According to this, the organic ferroelectric capacitor can be formed in a later process than the wiring layer.
(11) An organic ferroelectric memory according to the present invention comprises:
A storage capacitor type organic ferroelectric memory,
A substrate,
An organic thin film transistor formed above the substrate and having a source electrode, a drain electrode, an organic semiconductor layer, a gate insulating layer, and a gate electrode;
An interlayer insulating layer formed above the organic thin film transistor;
A first contact layer formed on the interlayer insulating layer;
A second contact layer formed on the interlayer insulating layer;
A wiring layer electrically connected to the organic thin film transistor through the first contact layer;
An organic ferroelectric capacitor electrically connected to the organic thin film transistor through the second contact layer and having a lower electrode, an organic ferroelectric layer, and an upper electrode;
including. According to the present invention, since the organic ferroelectric capacitor including the organic ferroelectric layer and the organic thin film transistor including the organic semiconductor layer are included, a low-temperature process of, for example, 150 ° C. or less is possible as a whole. Therefore, the restriction on the heat resistance of the substrate is relaxed, and the degree of freedom of selection of the substrate is improved. In addition, since the organic ferroelectric material can be processed with low energy, the manufacturing process can be facilitated. Furthermore, there is no problem of environmental load due to heavy metals, it can be easily disposed of and it is easy to handle.
(12) An organic ferroelectric memory according to the present invention comprises:
A storage capacitor type organic ferroelectric memory,
A substrate,
An organic ferroelectric capacitor formed above the substrate and having a lower electrode, an organic ferroelectric layer and an upper electrode;
An interlayer insulating layer formed above the organic ferroelectric capacitor;
An organic thin film transistor formed above the interlayer insulating layer and having a source electrode, a drain electrode, an organic semiconductor layer, a gate insulating layer and a gate electrode;
A first contact layer electrically connected to the organic thin film transistor;
A wiring layer electrically connected to the first contact layer;
A second contact layer penetrating the interlayer insulating layer and electrically connecting the organic thin film transistor and the organic ferroelectric capacitor;
including. According to the present invention, since the organic ferroelectric capacitor including the organic ferroelectric layer and the organic thin film transistor including the organic semiconductor layer are included, a low-temperature process of, for example, 140 ° C. or less is possible as a whole. Therefore, the restriction on the heat resistance of the substrate is relaxed, and the degree of freedom of selection of the substrate is improved. In addition, since the organic ferroelectric material can be processed with low energy, the manufacturing process can be facilitated. Furthermore, there is no problem of environmental load due to heavy metals, it can be easily disposed of and it is easy to handle.
(13) In this organic ferroelectric memory,
The organic semiconductor layer is formed above the source electrode and the drain electrode,
The gate insulating layer is formed above the organic semiconductor layer,
The gate electrode may be formed above the gate insulating layer.
(14) In this organic ferroelectric memory,
The source electrode and the drain electrode are formed above the organic semiconductor layer,
The gate insulating layer is formed above the source electrode and the drain electrode,
The gate electrode may be formed above the gate insulating layer.
(15) In this organic ferroelectric memory,
The gate insulating layer is formed above the gate electrode,
The source electrode and the drain electrode are formed above the gate insulating layer,
The organic semiconductor layer may be formed above the source electrode and the drain electrode.
(16) In this organic ferroelectric memory,
The gate insulating layer is formed above the gate electrode,
The organic semiconductor layer is formed above the gate insulating layer,
The source and drain electrodes may be formed above the organic semiconductor layer.
(17) In this organic ferroelectric memory,
The substrate may be an organic substrate.

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

  1 to 7 are diagrams showing a method of manufacturing an organic ferroelectric memory according to the present embodiment. FIGS. 8 and 9 are diagrams showing an organic ferroelectric memory and a circuit thereof according to the present embodiment, respectively. It is.

(Manufacturing method of organic ferroelectric memory)
In the present embodiment, a storage capacitor type (for example, a so-called one-transistor one-capacitor type) organic ferroelectric memory is manufactured.

  (1) As shown in FIGS. 1 to 4, an organic thin film transistor (organic TFT) 120 is formed on a substrate 100.

  First, as shown in FIG. 1, a substrate 100 is prepared. The substrate 100 may be an organic substrate (resin substrate, plastic substrate). The organic substrate contains an organic material in at least a part thereof, and examples thereof include a polyethylene terephthalate substrate, a polyethylene naphthalate substrate, a polyaramid substrate, a polyphenylin sulfide substrate, a polyolefin substrate, a polyimide substrate, and an epoxy substrate. A film-like flexible substrate may be used as the organic substrate. As a modification, the substrate 100 may be a glass substrate, an electro-optical element such as a liquid crystal element or an EL element, or another electronic component mounted or built therein. In this embodiment mode, all processes performed on the substrate 100 can be performed at a low temperature (for example, a maximum temperature of about 140 ° C.). Improvement can be achieved.

  (1-1) As shown in FIG. 1, a source electrode 110 and a drain electrode 112 are formed on a substrate 100. The source electrode 110 and the drain electrode 112 may be formed on the upper surface of the substrate 100 or may be formed on the substrate 100 via a buffer layer or a surface modification layer (not shown).

  The source electrode 110 and the drain electrode 112 can be formed by a droplet discharge method in which the ink 104 is discharged from the droplet discharge portion (for example, a printer head) 102. The ink 104 may be a dispersion liquid containing conductive fine particles (for example, a conductive organic material ink or a metal ink). Examples of the conductive fine particles include metal fine particles such as gold, silver, copper, platinum, palladium, nickel, and aluminum, fine particles of a conductive organic material, and other fine particles such as a superconductor or a conductive oxide. The fine particles are not particularly limited in size, and are particles that can be discharged together with the dispersion. The conductive fine particles may be coated with a coating material such as organic matter in order to suppress the reaction. The dispersion may be difficult to dry and re-dissolvable. The conductive fine particles may be uniformly dispersed in the dispersion. Examples of the conductive organic material include polyethylene dioxane thiophene (PEDOT) doped with polystyrene sulfonate (PSS), which is a conductive polymer, or polyaniline. If necessary, a treatment for volatilizing the dispersion and a treatment (heating) for bonding (for example, sintering) the conductive fine particles to each other are performed.

  As a droplet discharge method, a spin coating method, a micro-dispensing method, an ink jet method, a bubble jet (registered trademark) method, a gel jet (registered trademark) method, or a solution atomizing method (LSMCD: Liquid Source Misted Chemical Deposition) is applied. can do. For example, according to the ink jet method, by applying a technique that has been put to practical use for an ink jet printer, ink can be provided at high speed and without waste. By applying the droplet discharge method, the source electrode 110 and the drain electrode 112 having a predetermined pattern can be directly formed without using expensive and time-consuming photolithography technology and etching technology.

  Before applying the ink 104, the upper surface of the substrate 100 may be surface-treated as necessary. For example, a liquid repellent treatment is performed on a region other than the region for forming the source electrode 110 and the drain electrode 112. Accordingly, even when the ejected ink 104 is not dropped on the region for forming the source electrode 110 and the drain electrode 112, the source electrode 110 and the drain electrode 112 having a predetermined pattern can be formed.

  Note that the film formation method of the source electrode 110 and the drain electrode 112 is not limited to the above-described droplet discharge method, and other methods such as a sputtering method, a vapor deposition method, and a plating method may be applied. it can.

  (1-2) As shown in FIG. 2, the organic semiconductor layer 114 is formed on the source electrode 110 and the drain electrode 112. The liquid containing the material of the organic semiconductor layer 114 is used, and the organic semiconductor layer 114 can be formed by a liquid phase process (for example, a spin coat method or a droplet discharge method). For example, the organic semiconductor layer 114 having a predetermined pattern may be directly formed by applying the above-described droplet discharge method. That is, as shown in FIG. 2, the organic semiconductor layer 114 is formed in a predetermined pattern so that a hole 114a exposing the source electrode 110 and a hole 114b exposing the drain electrode 112 are formed.

  As a material of the organic semiconductor layer 114, for example, F8T2 which is one of fluorene-thiophene copolymers can be given. As the organic semiconductor layer, any of the following high molecular organic semiconductor materials and low molecular organic semiconductor materials can be used. Examples of the polymer organic semiconductor material include poly (3-alkylthiophene) (poly (3-hexylthiophene) (P3HT), poly (3-octylthiophene), poly (2,5-thienylenevinylene) (PTV). ), Poly (para-phenylene vinylene) (PPV), poly (9,9-dioctylfluorene-co-bis-N, N ′-(4-methoxyphenyl) -bis-N, N′-phenyl-1,4 -Phenylenediamine) (PFMO), poly (9,9 dioctylfluorene-co-benzothiadiazole) (BT), fluorene-triallylamine copolymer, triallylamine-based polymer, fluorene-thiophene copolymer, poly (3,4) -Ethylenedioxythiophene / styrene sulfonic acid) (PEDOT / PSS), polythiophene, poly (thio Fenvinylene), poly (2,2′-thienylpyrrole), polyaniline, etc. Examples of the low molecular organic semiconductor include C60, metal phthalocyanine, substituted derivatives thereof, anthracene, Acene molecular materials such as tetracene, pentacene, hexacene, etc., or α-oligothiophenes, specifically quarterthiophene (4T), sexithiophene (6T), octithiophene (8T), dihexyl quarterthiophene (DH4T), dihe Examples include kirsekithiophene (DH6T).

  By using an organic material as the material for the semiconductor layer, a low-temperature process can be performed, and for example, the semiconductor layer can be formed very easily compared to the case of using silicon. Note that a known method such as an evaporation method can be applied as a method of forming the organic semiconductor layer 114.

  (1-3) As shown in FIG. 3, the gate insulating layer 116 is formed on the organic semiconductor layer 114. The gate insulating layer 116 can be formed by a film formation process using a liquid material using a liquid containing the material of the gate insulating layer 116. For example, the above-described droplet discharge method may be applied to directly form the gate insulating layer 116 having a predetermined pattern. That is, as shown in FIG. 3, the gate insulating layer 116 is formed in a predetermined pattern so that the hole 116a exposing the source electrode 110 and the hole 116b exposing the drain electrode 112 are formed.

  The deposition temperature of the gate insulating layer 116 is preferably lower than the heat resistant temperature of the organic semiconductor layer 114. For example, when an insulating organic material such as polymethyl methacrylate (PMMA) is used, the gate insulating layer 116 can be formed at a temperature lower than the heat resistant temperature of the organic semiconductor layer 114.

  (1-4) As shown in FIG. 4, the gate electrode 118 is formed on the gate insulating layer 116. The liquid containing the material of the gate electrode 118 can be used, and the gate electrode 118 can be formed by a liquid phase process (for example, a droplet discharge method). For example, the above-described droplet discharge method may be applied to directly form the gate electrode 118 having a predetermined pattern. The material described for the source electrode 110 and the drain electrode 112 can be applied to the material of the gate electrode 118; for example, the same material as that of the source electrode 110 and the drain electrode 112 may be used. If necessary, a treatment for volatilizing the dispersion and a treatment (heating) for bonding (for example, sintering) the conductive fine particles to each other are performed. Examples of other film formation methods for the gate electrode 118 include sputtering, vapor deposition, and plating.

  Depending on the material of the gate insulating layer 116, a receiving layer (not shown) may be formed before the gate electrode 118 is formed. For example, when the gate insulating layer 116 is made of a material having high water repellency and the liquid material of the gate electrode 118 is water-soluble, it is difficult to apply the gate electrode 118 in a desired shape. Thus, by forming a receiving layer made of polyvinylphenol (PVP) or the like in advance, the gate electrode 118 having a desired shape can be formed more easily.

  Thus, the organic thin film transistor 120 can be formed. The organic thin film transistor 120 includes a source electrode 110, a drain electrode 112, an organic semiconductor layer 114, a gate insulating layer 116, and a gate electrode 118. The organic thin film transistor 120 shown in FIG. 4 is a so-called top gate / bottom contact type organic TFT.

  (2) As shown in FIG. 5, an interlayer insulating layer 122 is formed on the organic thin film transistor 120.

  As a material of the interlayer insulating layer 122, a material that can be formed at a temperature lower than the heat resistant temperature of the organic semiconductor layer 114 is preferable. For example, tetramethylsilane (TMS), polymethyl methacrylate (PMMA), photocurable resin (for example, UV curable resin), or the like can be given. By using these, damage to the organic semiconductor layer 114 due to heat can be reduced.

  Examples of the film forming method include a CVD method and a droplet discharge method. For example, as shown in FIG. 5, an interlayer insulating layer 122 having a predetermined pattern may be directly formed by applying the above-described droplet discharge method. Specifically, the interlayer insulating layer 122 is formed in a predetermined pattern so that the hole 122a exposing the source electrode 110 and the hole 122b exposing the drain electrode 112 are formed.

  (3) Next, as shown in FIGS. 6 and 7, first and second contact layers 124 and 126, a wiring layer 130, and an organic ferroelectric capacitor 140 are formed.

  (3-1) The first contact layer 124 is formed so as to penetrate the interlayer insulating layer 122 and be electrically connected to the organic thin film transistor 120 (for example, the drain electrode 112). Specifically, the first contact layer 124 is formed so as to fill the holes 114b, 116b, and 122b. The liquid containing the material of the first contact layer 124 may be used, and the first contact layer 124 may be formed by a liquid phase process (for example, a droplet discharge method).

  The first contact layer 124 may be formed only inside a predetermined hole (holes 114b, 116b, 122b), or may be formed so as to reach not only the inside but also the upper surface of the interlayer insulating layer 122. Good. In the latter case, as shown in FIG. 6, the first contact layer 124 and the wiring layer 130 may be formed integrally (continuously). If the ink amount and the ink application region are controlled by the droplet discharge method, the first contact layer 124 and the wiring layer 130 can be formed by the same droplet discharge step. Therefore, the manufacturing process can be simplified. Alternatively, after the first contact layer 124 is formed, the wiring layer 130 may be formed separately by the same or different technique. Note that the above-described contents can be applied to the materials of the first contact layer 124 and the wiring layer 130 and details of the film formation method.

  (3-2) The second contact layer 126 is formed so as to penetrate the interlayer insulating layer 122 and be electrically connected to the organic thin film transistor 120 (for example, the source electrode 110). Specifically, the second contact layer 126 is formed so as to fill the holes 114a, 116a, and 122a.

  As shown in FIG. 6, the second contact layer 126 and the lower electrode 142 of the organic ferroelectric capacitor 140 may be formed integrally (continuously). If the ink amount and the ink application region are controlled by the droplet discharge method, the second contact layer 126 and the lower electrode 142 can be formed by the same droplet discharge step. Therefore, the manufacturing process can be simplified. Alternatively, after the second contact layer 126 is formed, the lower electrode 142 may be formed separately by the same or different technique. Note that the first contact layer 124 and the above description can be applied to other contents of the second contact layer 126.

  (3-3) As shown in FIG. 7, the organic ferroelectric capacitor 140 having the lower electrode 142, the organic ferroelectric layer 144, and the upper electrode 146 is formed. For example, the lower electrode 142 and the second contact layer 126 are electrically connected to each other. The lower electrode 142 and the wiring layer 130 can be formed on the interlayer insulating layer 122. That is, the organic ferroelectric capacitor 140 and the wiring layer 130 can be formed in the same level layer.

  The contents of the source electrode 110 and the like can be applied to the material and the film formation method of the lower electrode 142. In particular, when the material of the lower electrode 142 is a conductive organic material, the hysteresis characteristic of the organic ferroelectric capacitor 140 is improved.

  Next, an organic ferroelectric layer 144 is formed on the lower electrode 142. Examples of the organic ferroelectric material of the organic ferroelectric layer 144 include poly (vinylidene fluoride / trifluoroethylene) (P (VDF / TrFE)), polyvinylidene fluoride (PVDF), and vinylidene fluoride / trifluoroethylene). Examples include co-oligomers (VDF / TrFE), vinylidene fluoride oligomers (VDF), and odd-numbered nylons. For example, after poly (vinylidene fluoride / trifluoroethylene) having a VDF: TrFE ratio of 75:25 is dissolved in a solvent (for example, a ketone-based solvent) to form a predetermined solution, a film is formed on a region including the lower electrode 142. Then, it is annealed at about 140 ° C. and crystallized. In the case of an organic ferroelectric material, annealing can be performed at an extremely low temperature as compared with an inorganic ferroelectric material. Therefore, the degree of freedom in selecting the substrate 100 used in the manufacturing process is high. Further, since the wiring layer 130 is not damaged by heat, the wiring layer 130 can be formed in a pre-process before the organic ferroelectric capacitor 140, and the manufacturing flexibility is high. Further, the manufacturing process can be facilitated by low energy treatment. Furthermore, since the orientation of the organic ferroelectric material does not depend much on the base (lower electrode 142), the degree of freedom in selecting the material of the lower electrode 142 can be improved. In addition, since the organic ferroelectric material does not contain heavy metal, there is no problem of environmental load, and handling that can be easily disposed of is easy.

  Examples of the method for forming the organic ferroelectric layer 144 include a vacuum deposition method, an LB (Langmuir-Blodgett) method, and the above-described droplet discharge method. According to the droplet discharge method, the organic ferroelectric layer 144 having a predetermined pattern can be directly formed. In the case of the droplet discharge method, it can be directly formed in a predetermined pattern in the same manner by combining selective growth techniques. In the case of other methods, the organic ferroelectric layer 144 may be patterned by etching as necessary.

  Thereafter, the upper electrode 146 is formed on the organic ferroelectric layer 144. As the material and formation method of the upper electrode 146, the contents of the lower electrode 142 described above can be applied. For example, if the material of the upper electrode 146 is a conductive organic material, the hysteresis characteristic of the organic ferroelectric capacitor 140 is improved as described above. In the case of the upper electrode 146, it is preferable to form the film so that the organic ferroelectric layer 144 serving as a base is not damaged.

  Thus, the organic ferroelectric capacitor 140 can be formed. The organic ferroelectric capacitor 140 is electrically connected to the organic thin film transistor 120 (for example, the source electrode 110) through the second contact layer 126. The organic thin film transistor 120 functions as a selection transistor that selects on / off of charge accumulation in the organic ferroelectric capacitor 140.

  (4) Thereafter, as shown in FIG. 8, an insulating layer 150 is formed on the organic ferroelectric capacitor 140. The insulating layer 150 may be an interlayer insulating layer for further forming a device thereon, or may be an uppermost passivation layer. The insulating layer 150 is formed so as to cover the organic ferroelectric capacitor 140. If the film formation temperature of the insulating layer 150 is lower than the film formation temperature of the organic ferroelectric layer 144, for example, the heat damage of the organic ferroelectric capacitor 140 can be reduced. The material of the insulating layer 150 and the film formation method can employ the contents of the interlayer insulating layer 122.

  Through the above steps, an organic ferroelectric memory 1000 can be manufactured as shown in FIG. All the above film forming processes can be performed by a liquid phase process. In particular, if the droplet discharge method is applied, it is possible to manufacture using the same discharge device by simply changing the droplet material, so that an extremely inexpensive and easy manufacturing process can be realized.

(Structure of organic ferroelectric memory)
As shown in FIG. 8, the organic ferroelectric memory 1000 includes a substrate 100, an organic thin film transistor 120, an interlayer insulating layer 122, first and second contact layers 124 and 126, a wiring layer 130, and an organic strong memory. And a dielectric capacitor 140. In the example shown in FIG. 8, the organic thin film transistor 120 has a so-called top gate / bottom contact type structure. Specifically, the organic semiconductor layer 114 is formed over the source electrode 110 and the drain electrode 112, the gate insulating layer 116 is formed over the organic semiconductor layer 114, and the gate electrode 118 is formed over the gate insulating layer 116. Note that the structure of the organic thin film transistor is not limited to that shown in FIG. 8, and can take various forms as described later.

  Referring to the circuit diagram of FIG. 9, the word line (WL) is electrically connected to the gate electrode 118 of the organic thin film transistor 120, the bit line (BL) is electrically connected to the wiring layer 130, and the plate line (PL). Is electrically connected to the upper electrode 146 of the organic ferroelectric capacitor 140.

  According to this organic ferroelectric memory 1000, in addition to the effects described above, in particular, the load applied to each other can be reduced by combining with other flexible materials such as organic substrates, organic semiconductors, conductive organic materials, and insulating organic materials. It is possible to reduce and provide a flexible memory with higher performance.

  The organic ferroelectric memory according to the present embodiment includes contents that can be derived from the manufacturing method described above.

(First modification)
FIG. 10 is a diagram showing a first modification of the present embodiment, and is a diagram for explaining an organic ferroelectric memory and a manufacturing method thereof.

  In this modification, the organic ferroelectric capacitor 240 is formed above the wiring layer 130. That is, after forming the wiring layer 130, the intermediate insulating layer 160 is formed on the wiring layer 130, and the organic ferroelectric capacitor 240 is formed on the intermediate insulating layer 160. In that case, the organic thin film transistor 120 and the organic ferroelectric capacitor 240 can be electrically connected by the second contact layer 226 that continuously passes through the interlayer insulating layer 122 and the intermediate insulating layer 160. The content of the interlayer insulating layer 122 can be applied to a method and a material for forming the intermediate insulating layer 160.

  According to this modification, since the organic ferroelectric capacitor 240 including the organic ferroelectric layer is formed, for example, the necessary film formation temperatures of the interlayer insulating layer 160, the wiring layer 130, the interlayer insulating layer 122, and the organic thin film transistor are set. Even when the temperature is higher than the heat resistant temperature of the organic ferroelectric capacitor 240, the elements such as the wiring layer 130 are not damaged by heat. Further, since the formation process of the organic thin film transistor 120 and other conductive parts (such as the wiring layer 130) and the formation process of the organic ferroelectric capacitor 240 can be performed separately, any one process is restricted by the other. Thus, the manufacturing flexibility can be improved.

(Second modification)
FIG. 11 is a diagram showing a second modification of the present embodiment, and is a diagram for explaining an organic ferroelectric memory and a manufacturing method thereof.

  In this modification, an organic ferroelectric capacitor 340 and an organic thin film transistor 320 are arranged in order from the substrate 100. Specifically, the organic ferroelectric capacitor 340 is formed on the substrate 100, the interlayer insulating layer 122 is formed on the organic ferroelectric capacitor 340, the organic thin film transistor 320 is formed on the interlayer insulating layer 122, and the organic thin film transistor 320 is formed. An insulating layer 150 is formed on the substrate. The details described above can be applied to the details of the organic ferroelectric capacitor 340 and the organic thin film transistor 320 except that the positions relative to the substrate 100 are different. In the example shown in FIG. 11, the first contact layer 324 is provided on the organic thin film transistor 320 (the drain electrode 312 in the figure), and the wiring layer 330 is formed on the insulating layer 150. Instead, the wiring layer 330 may be formed on the same level layer as the organic ferroelectric capacitor 340 (that is, on the substrate 100). The second contact layer 326 penetrates the interlayer insulating layer 122 and electrically connects the organic ferroelectric capacitor 340 and the organic thin film transistor 320. For example, the second contact layer 326 electrically connects the upper electrode 346 and the source electrode 310. ing.

  According to this modification, by forming the organic thin film transistor 320 above the organic ferroelectric capacitor 340, the organic ferroelectric capacitor 340 can be formed before the organic thin film transistor 320 is formed. Thereby, for example, when the film formation temperature of the organic ferroelectric layer is higher than the heat resistant temperature of the organic semiconductor layer, it is possible to prevent the organic semiconductor layer from being damaged by the annealing process during the film formation of the organic ferroelectric layer. .

(Third Modification)
12 to 14 are views showing a third modification of the present embodiment, and are diagrams for explaining an organic ferroelectric memory and a manufacturing method thereof. In this modification, the structure of the organic thin film transistor is different from that described above.

  (1) In the example shown in FIG. 12, the organic thin film transistor 420 has a so-called top gate / top contact type structure. Specifically, the source electrode 410 and the drain electrode 412 are formed over the organic semiconductor layer 414, the gate insulating layer 416 is formed over the source electrode 410 and the drain electrode 412, and the gate electrode 418 is formed over the gate insulating layer 416. Yes. Note that the above-described contents can be applied to these materials and film formation methods.

  (2) In the example shown in FIG. 13, the organic thin film transistor 520 has a so-called bottom gate / bottom contact type structure. Specifically, a gate insulating layer 516 is formed over the gate electrode 518, a source electrode 510 and a drain electrode 512 are formed over the gate insulating layer 516, and an organic semiconductor layer 514 is formed over the source electrode 510 and the drain electrode 512. Yes. Note that the above-described contents can be applied to these materials and film formation methods.

  (3) As shown in FIG. 14, the organic thin film transistor 620 has a so-called bottom gate / top contact type structure. Specifically, a gate insulating layer 616 is formed over the gate electrode 618, an organic semiconductor layer 614 is formed over the gate insulating layer 616, and a source electrode 610 and a drain electrode 612 are formed over the organic semiconductor layer 614. Note that the above-described contents can be applied to these materials and film formation methods.

(Fourth modification)
FIG. 15 is a diagram showing a fourth modification of the present embodiment, and is a circuit diagram of an organic ferroelectric memory. In the above description, an example of a one-transistor one-capacitor type has been described. However, the present invention is not limited to this, and can be applied to a so-called two-transistor two-capacitor type organic ferroelectric memory. According to this memory structure, in addition to the above-described effects, the operation stability is high, and there is a feature that the memory structure is strong against characteristic variation caused by a manufacturing process or the like. Alternatively, the contents of the present invention may be applied to another storage capacity type other than the above-described 1T1C type and 2T2C type.

(Fifth modification)
16 to 19 are views showing a fifth modification of the present embodiment, and are diagrams showing a method for manufacturing an organic ferroelectric memory. In this modification, the patterning method of the organic ferroelectric capacitor 140 is different from that described above.

  First, as shown in FIG. 16, a lower electrode 142a, an organic ferroelectric layer 144a, and an upper electrode 146a are sequentially stacked in a region including a predetermined pattern and its periphery. Thereafter, as shown in FIG. 17, the upper electrode 146 is formed by patterning. For example, patterning can be performed by wet etching. Alternatively, the upper electrode 146 having a predetermined pattern may be directly formed on the organic ferroelectric layer 144a by a droplet discharge method.

  Thereafter, as shown in FIG. 17, the organic ferroelectric layer 144a is ashed using the upper electrode 146 having a predetermined pattern as a mask. That is, a region exposed from the mask (upper electrode 146) in the organic ferroelectric layer 144a is volatilized and removed by a reactive gas (for example, plasma oxygen gas). Thus, as shown in FIG. 18, the organic ferroelectric layer 144 can be formed in the same pattern as the upper electrode 146.

  Alternatively, by patterning the upper electrode 146 by dry etching, the organic ferroelectric layer 144 may be simultaneously patterned by the same action as ashing.

  In addition, as shown in FIG. 19, the organic ferroelectric capacitor 140 can be formed by patterning the lower electrode 142 by a predetermined method.

  According to this modification, by using the upper electrode 146 as a mask, it is not necessary to form a mask for patterning the organic ferroelectric layer 144, and the manufacturing process can be facilitated.

  In addition, this invention further contains the form which can be guide | induced by combining the content of at least 2 or more of the some modified example mentioned above.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same purposes and results). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

It is a figure which shows the manufacturing method of the organic ferroelectric memory which concerns on embodiment of this invention. It is a figure which shows the manufacturing method of the organic ferroelectric memory which concerns on embodiment of this invention. It is a figure which shows the manufacturing method of the organic ferroelectric memory which concerns on embodiment of this invention. It is a figure which shows the manufacturing method of the organic ferroelectric memory which concerns on embodiment of this invention. It is a figure which shows the manufacturing method of the organic ferroelectric memory which concerns on embodiment of this invention. It is a figure which shows the manufacturing method of the organic ferroelectric memory which concerns on embodiment of this invention. It is a figure which shows the manufacturing method of the organic ferroelectric memory which concerns on embodiment of this invention. 1 is a diagram showing an organic ferroelectric memory according to an embodiment of the present invention. 1 is a circuit diagram of an organic ferroelectric memory according to an embodiment of the present invention. It is a figure which shows the modification of embodiment of this invention. It is a figure which shows the modification of embodiment of this invention. It is a figure which shows the modification of embodiment of this invention. It is a figure which shows the modification of embodiment of this invention. It is a figure which shows the modification of embodiment of this invention. It is a figure which shows the modification of embodiment of this invention. It is a figure which shows the modification of embodiment of this invention. It is a figure which shows the modification of embodiment of this invention. It is a figure which shows the modification of embodiment of this invention. It is a figure which shows the modification of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Substrate 110 ... Source electrode 112 ... Drain electrode 114 ... Organic semiconductor layer 116 ... Gate insulating layer 118 ... Gate electrode 120 ... Organic thin film transistor 122 ... Interlayer insulating layer 124 ... First contact layer 126 ... Second contact layer 130 ... Wiring layer 140 ... Organic ferroelectric capacitor 142 ... Lower electrode 144 ... Organic ferroelectric layer 146 ... Upper electrode 150 ... Insulating layer 160 ... Intermediate insulating layer 226 ... Second contact layer 240 ... Organic ferroelectric capacitor 310 ... Source Electrode 312 ... Drain electrode 320 ... Organic thin film transistor 324 ... First contact layer 326 ... Second contact layer 330 ... Wiring layer 340 ... Organic ferroelectric capacitor 410 ... Source electrode 412 ... Drain electrode 416 ... Gate insulating layer 418 ... Gate Electrode 420 ... Organic thin film Transistor 510 ... source electrode 512 ... drain electrode 514: organic semiconductor layer 516 ... gate insulating layer 520 ... organic film transistor 610 ... source electrode 612 ... drain electrode 614: organic semiconductor layer 616 ... gate insulating layer 620 ... organic film transistor

Claims (17)

An organic ferroelectric memory manufacturing method comprising:
(A) forming an organic thin film transistor having a source electrode, a drain electrode, an organic semiconductor layer, a gate insulating layer and a gate electrode above the substrate;
(B) forming an interlayer insulating layer above the organic thin film transistor;
(C) forming a first contact layer electrically connected to the organic thin film transistor in the interlayer insulating layer and a second contact layer electrically connected to the organic thin film transistor in the interlayer insulating layer;
(D) forming a wiring layer electrically connected to the first contact layer;
(E) forming an organic ferroelectric capacitor electrically connected to the second contact layer and having a lower electrode, an organic ferroelectric layer and an upper electrode;
A method for manufacturing an organic ferroelectric memory, comprising: In the manufacturing method of the organic ferroelectric memory of Claim 1,
A method of manufacturing an organic ferroelectric memory, wherein the steps (a) to (e) are performed by a liquid phase process. In the manufacturing method of the organic ferroelectric memory of Claim 1 or Claim 2,
In the step (a), at least one of the source electrode, the drain electrode, the organic semiconductor layer, the gate insulating layer, and the gate electrode is formed in a predetermined pattern by a droplet discharge method. Manufacturing method of body memory. In the manufacturing method of the organic ferroelectric memory in any one of Claims 1-3,
A method for manufacturing a ferroelectric memory, wherein in the step (a), the organic semiconductor layer is formed of a fluorene-thiophene copolymer. In the manufacturing method of the organic ferroelectric memory in any one of Claims 1-4,
In the step (e), at least one of the lower electrode, the organic ferroelectric layer, and the upper electrode is formed in a predetermined pattern by a droplet discharge method. In the manufacturing method of the organic ferroelectric memory in any one of Claims 1-4,
In the step (e), the organic ferroelectric layer is formed by ashing the organic ferroelectric layer using the upper electrode having the predetermined pattern as a mask by forming the upper electrode to have a predetermined pattern. A method of manufacturing an organic ferroelectric memory, wherein a layer is patterned. In the manufacturing method of the organic ferroelectric memory in any one of Claims 1-6,
An organic ferroelectric memory, wherein at least one of the lower electrode and the upper electrode is formed of a conductive organic material in the step (e). In the manufacturing method of the organic ferroelectric memory in any one of Claims 1-7,
In the step (e), the organic ferroelectric layer is made of poly (vinylidene fluoride / trifluoroethylene), polyvinylidene fluoride, (vinylidene fluoride / trifluoroethylene) co-oligomer, vinylidene fluoride oligomer, and odd-number nylon. A method of manufacturing an organic ferroelectric memory formed by any of the above. In the manufacturing method of the organic ferroelectric memory in any one of Claims 1-8,
The method for manufacturing an organic ferroelectric memory, wherein the substrate is an organic substrate. In the manufacturing method of the organic ferroelectric memory in any one of Claims 1-9,
After the step (d), further comprising forming an intermediate insulating layer above the wiring layer;
A method of manufacturing an organic ferroelectric memory, wherein the organic ferroelectric capacitor is formed above the intermediate insulating layer in the step (e). A storage capacitor type organic ferroelectric memory,
A substrate,
An organic thin film transistor formed above the substrate and having a source electrode, a drain electrode, an organic semiconductor layer, a gate insulating layer, and a gate electrode;
An interlayer insulating layer formed above the organic thin film transistor;
A first contact layer formed on the interlayer insulating layer;
A second contact layer formed on the interlayer insulating layer;
A wiring layer electrically connected to the organic thin film transistor through the first contact layer;
An organic ferroelectric capacitor electrically connected to the organic thin film transistor through the second contact layer and having a lower electrode, an organic ferroelectric layer, and an upper electrode;
Including an organic ferroelectric memory. A storage capacitor type organic ferroelectric memory,
A substrate,
An organic ferroelectric capacitor formed above the substrate and having a lower electrode, an organic ferroelectric layer and an upper electrode;
An interlayer insulating layer formed above the organic ferroelectric capacitor;
An organic thin film transistor formed above the interlayer insulating layer and having a source electrode, a drain electrode, an organic semiconductor layer, a gate insulating layer and a gate electrode;
A first contact layer electrically connected to the organic thin film transistor;
A wiring layer electrically connected to the first contact layer;
A second contact layer formed on the interlayer insulating layer and electrically connecting the organic thin film transistor and the organic ferroelectric capacitor;
Including an organic ferroelectric memory. The organic ferroelectric memory according to claim 11 or 12,
The organic semiconductor layer is formed above the source electrode and the drain electrode,
The gate insulating layer is formed above the organic semiconductor layer,
An organic ferroelectric memory, wherein the gate electrode is formed above the gate insulating layer. The organic ferroelectric memory according to claim 11 or 12,
The source electrode and the drain electrode are formed above the organic semiconductor layer,
The gate insulating layer is formed above the source electrode and the drain electrode,
An organic ferroelectric memory, wherein the gate electrode is formed above the gate insulating layer. The organic ferroelectric memory according to claim 11 or 12,
The gate insulating layer is formed above the gate electrode,
The source electrode and the drain electrode are formed above the gate insulating layer,
An organic ferroelectric memory, wherein the organic semiconductor layer is formed above the source electrode and the drain electrode. The organic ferroelectric memory according to claim 11 or 12,
The gate insulating layer is formed above the gate electrode,
The organic semiconductor layer is formed above the gate insulating layer,
An organic ferroelectric memory, wherein the source and drain electrodes are formed above the organic semiconductor layer. The organic ferroelectric memory according to any one of claims 11 to 16,
An organic ferroelectric memory, wherein the substrate is an organic substrate.

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