Patent Application
20080017606
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
In the following embodiments, a surface energy difference bank will be formed in a part of a manufacturing process of a passive-matrix type ferroelectric memory device. It should be understood that the surface energy difference bank can be formed in a part of manufacturing process of other electronic devices in addition to the ferroelectric memory device, manufacturing process of electronic circuits or manufacturing process of electronic apparatuses.
In this description, the term “electronic device” encompasses ferroelectric memory devices, light emitting diodes, thin film transistors, electrochemical cells, photoelectric devices and the like. The word “electronic apparatus” encompasses liquid crystal display devices, plasma display devices, organic electroluminescence (EL) display devices, field emission displays (FEDs), surface-conduction electron-emitter displays (SEDs), electrophoretic display devices and the like.
Embodiments of the invention will be hereunder described with reference to the accompanying drawings. In the accompanying drawings, a scale size may be different in each component in order to make the component recognizable.
A. Stamp
Structure of a stamp which is used to form a surface energy difference bank is now described.
Referring to
The shape of an apical face 14a of each elastic element 14 is not particularly limited. The shape of the apical face 14a can be rectangle, triangle, circle, hexagon or other figures. The shape of the apical face 14a is rectangle in this embodiment. A length “A” (see
A plurality of the apical faces 14a forms a “contact region”. In this embodiment, the plurality of the apical faces 14a forms three contact regions 16, 17, 18. The apical faces 14a are arranged so as to form lines in each of the contact regions 16, 17, 18. More specifically, the apical faces 14a are arranged such that lines L1, L2, L3, L4 that extend in Y-axis direction are formed as shown in
A width of each of the contact regions 16, 17, 18 in the direction orthogonal to the direction in which the lines L1, L2, L3, L4 extend is set within a range of 10 nm-10 μm. A gap between the contact region 16 and the contact region 17 and a gap between the contact region 17 and the contact region 18 are also set within the range of 10 nm-10 μm.
A method for manufacturing the stamp will be described later.
B. Object
Referring now to
The lower electrode 22 which is provided in the plural number is formed on the substrate 21. The lower electrodes 22 extend in X-axis direction. A predetermined distance is provided between any adjacent two of the lower electrodes 22. The ferroelectric layer 23 covers the plurality of the lower electrodes 22 and the surface of the substrate 21 which is exposed among the lower electrodes 22. The surface layer covers the surface of the ferroelectric layer 23. The surface of the surface layer traces the shapes of the lower electrodes 22 which exit under the surface layer.
An “object face” in this embodiment is one like the surface of this surface layer. In other embodiments, the “object face” can be the face itself of the substrate 21, can be the surface of the ferroelectric layer or can be the surface of the plurality of the electrodes and the substrate 21. The “object face” can be flat or not flat through it is not flat in this embodiment. More specifically, the “object face” in this embodiment is the surface defined by the surface layer existing on the electrodes and the surface layer where the electrodes are not formed, and thereby the “object face” has a convex-concave figure on its surface.
More specifically, an object face 24 is made of upper faces 25, 27, 29, bottom faces 26, 28 and side faces that connect the upper faces 25, 27, 29 respectively with the bottom faces 26, 28. Each of the upper faces 25, 27, 29 is situated at the same level from the surface of the substrate 21. The bottom faces 26, 28 are situated at the same level from the surface of the substrate 21 but which is lower than the level of the upper faces 25, 27, 29 (see
C. Manufacturing Method for Ferroelectric Memory Device
C1. Example of Manufacturing Method for Object
Material containing poly-methyl-methacrylate (PMMA) is applied about 1 μm thick on the substrate 21 by a spin-coating method. The applied material is baked at 120° C. for 5 minutes to obtain a PMMA layer. The PMMA layer is then embossed by using a silicon chip. The silicon chip has a plurality of grooves, each of the grooves has a width of 10 μm and provided with a gap of 40 μm therebetween. Accordingly, a plurality of the grooves, each of which is 40 μm wide, is given to the PMMA layer.
An O2 plasma treatment is performed to the PMMA layer so as to expose the surface of the substrate 21 at each bottom face of the grooves. The grooves are then treated by a CF4 plasma process. This CF4 plasma process increases a liquid-repellency of the side faces of the grooves and increases a hydrophilicity of the bottom faces of the grooves. In other words, the CF4 plasma process generates the difference (contrast) in wettability between the side faces of the grooves (PMMA) and the bottom faces of the grooves (glass).
A silver suspension whose base is water is proved in the grooves by an ink-jet printing method. The provided suspension is then dried at 100° C. for 10 minutes to obtain silver lines. Each of the silver lines is a 100 nm thick. The remaining PMMA layer is removed with acetone. The silver lines are subsequently annealed at 150° C. for an hour. Accordingly, the plurality of the lower electrodes 22 made of the silver lines is obtained.
Copolymer of poly vinylidene fluoride and trifluoro ethylene (PVDF-TrFE) is then applied 500 nm thick on the substrate 21 and the plurality of the electrodes by the spin-coating method. The applied PVDF-TrFE copolymer is baked at 140° C. for an hour to obtain a ferroelectric layer made of the PVDF-TrFE copolymer layer. PMMA or the like is subsequently applied 50 nm thick on the obtained uneven face which is the ferroelectric layer by the spin-coating method. The applied PMMA is baked at 100° C. for 20 minutes so as to obtain the surface layer made of PMMA. The surface of the surface layer is then treated with O2 plasma for 1 minuet.
The object 20 can be obtained in the above-described way.
C2. Method for Forming Surface Energy Difference Bank
Next, a method for forming the surface energy difference bank will be now described with reference to
A material 30 for forming a self-assembled molecular film is applied onto the contact regions 16, 17, 18 which are the apical faces 14a of the elastic elements 14 protruding out from the base part 12 of the stamp 10. In this embodiment, a hexane solution containing about 0.01 mol/l of 1H, 1H, 2H, 2H-perfluoro-decyl-trichlorosilane as the material 30 is applied onto the contact regions 16, 17, 18.
In this embodiment, the degree of the liquid-repellency of the material 30 of the self-assembled molecular film is higher than that of the object face 24. The self-assembled molecular film material 30 having such repellency can be for example fluoroalkylsilane. The hydrophilicity of the self-assembled molecular film material 30 can be higher than the hydrophilicity of the object face 24 in other embodiments.
Though 1H, 1H, 9H, 2H-perfluoro-decyl-trichlorosilane is used as the material 30 in this embodiment, other materials can be also adopted instead. For example, a material composed of a molecule having —CF3, —CH3(CH2)n, —NH2, —OH or —COOH at its one end and silane or thiol at the other end depending on the type of the base surface. The solution of the molecule having —CF3, —CH3(CH2)n or the like serves as the material having liquid-repellency and the solution of the molecule having —NH2, —OH, —COOH or the like serves as the material having hydrophilicity.
The stamp 10 is pressed against the object 20 (in the direction of the arrow shown in
Referring to
In the above-described way, it is possible to contact the material 30 with areas that are situated in at least two different levels on the object face 24 such as the upper face 25 and the bottom face 26 by stamping the stamp 10 on the object face 24 for example only once. This means that the step of contacting the upper face 25 with the material 30 and the step of contacting the bottom face 26 which positions at a lower level than the upper face 25 with the material 30 can be performed at the same time.
When the material touches the object face 24, the molecules of the self-assembled molecular film material 30 and the molecules forming the object face 24 strongly bind each other and the self-assembled molecular film material 30 is transferred to the object face 24 from the contact regions 16, 17, 18.
Consequently, banks 34, 35, 36 composed of dots 32 made of the self-assembled molecular film which corresponds to the elastic elements 14 can be obtained on the object; face 24 that traces the convex-concave figure as shown in
In each of the banks 34, 35, 36, a plurality of dots 32 are arranged in lines L5, L6, L7, L8 which respectively correspond to the lines L1, L2, L3, L4 of the apical faces 14a. Each of the lines L5, L6, L7, L8 can control the flow of a functional liquid so that the banks 34, 35, 36 can prevent the functional liquid from flowing across the plurality of dots 32. In this way, it is possible to prevent overflow of the functional liquid and generation of bridges if the functional liquid is provided onto the area surrounded by these surface energy difference banks by the ink-jet printing method.
Accordingly, the surface energy difference bank made of the self-assembled molecular film can be uniformly formed throughout the object face 24 even if the object face 24 of the substrate is not flat.
C3. Method for Forming Upper Electrodes
A method for forming the upper electrodes will be now described with reference to
Referring to
The water-based colloidal silver suspension is one kind of the “functional liquid”. In this embodiment, the “functional liquid” refers to a material having a viscosity with which the material can be discharged from the nozzle in the form of the droplet 38. In this case, the “functional liquid” can be either water-based or oil-based material. It is required to have the liquidity (a low viscosity) with which the material can be discharged from the nozzle but it can contain a solid matter as long as it can serve as fluid as a whole. The viscosity of the “functional liquid” is preferably set within a range of 1-50 mPa·s. This is because where the droplet 38 of the “functional liquid” is discharged, the area around the nozzle will not be easily contaminated with the “functional liquid” if the viscosity is equal or larger than 1 mPa·s. If the viscosity is equal or smaller than 50 mPa·s, the frequency of clogging occurring at the nozzle decreases, helping the droplet 38 to be smoothly discharged.
The predetermined material contained in the functional liquid includes for example conductive materials, ferroelectric materials, semiconductor materials, dielectric materials and electric light emitting materials such as organic electroluminescence (EL) materials. Where the functional liquid contains a conductive material, a conductive pattern such as the lower electrode 22 and the upper electrode in the above-described embodiment can be obtained. Where the functional liquid contains a semiconductor material, a semiconductor pattern can be obtained. Where the functional liquid contains a dielectric material, a dielectric pattern can be obtained. Where the functional liquid contains a electric light emitting material, a electric light emitting pattern can be obtained.
D. Method for Manufacturing Stamp
A method for manufacturing the stamp according to the embodiment of the invention will be now described.
The stamp can be manufactured by pressing a base member made of PDMS or the like onto a master which is manufactured by photolithography and the like and molding it by heat. Firstly, Example 1 in which a stamp having the micron-sized apical face of the elastic element is manufactured by a photolithography method is hereunder described.
A master which is used for the formation of the stamp is manufactured in advance. Referring to
Referring to
Next, a base member (unshown in the drawings) used for manufacturing the stamp 10 is prepared. The base member for the stamp 10 is for example a 2 μm thick plate made of PDMS. The base member for the stamp 10 is pressed onto the face of the master 40 on which the photo-resist film 44 has been formed and it is kept being pressed for an hour at 70° C. Though this process, elastic elements 52 each of which corresponds to each hole 48 and a base part 54 that has a face contacts with the upper face of the photo-resist film 44 are formed in the base member of the stamp 10. Each of the elastic elements 52 has an apical face 52a whose shape is a rectangular of 1 μm on a side. Each of the elastic elements 52 is provided with a 1 μm gap each other and so as to form lines, each of the line is 20 μm long.
Referring now to
D. Method for Manufacturing Stamp
Secondly, Example 2 in which a high-resolution stamp having the submicron-sized or smaller than submicron-sized apical face of the elastic element is manufactured by a photolithography technique and a lift-off technique is hereunder described. Descriptions of the same structures or process as those of Example 1 will be hereunder omitted.
A master which is used for the formation of the stamp is manufactured in advance, Referring to
Referring now to
Subsequently, a structure 70 including the substrate 62, the photo-resist film 64 and the metal thin films 68, 69 is immersed into a solvent of the photo-resist film 64, though which is not shown in the drawings. At this point, the photo-resist film 64 is dissolved in the solvent and removed. Accordingly, the metal thin film 69 that exists on the photo-resist film 64 is removed. Consequently, the photo-resist film 64 and the metal thin film 69 that exists on the photo-resist film 64 are removed and only the metal thin film 68 remains on the substrate 62 as shown in
Referring to
Referring now to
Referring to
Next, a part of the substrate 62 where is not covered with the metal thin film 68 or the dots 74 is etched. This etching of the substrate 62 can be performed by for example O2+CF4 plasma etching. The metal thin film 68 and the dots 74 on the substrate are removed in a KOH solution. In this way, the master 60 having a concave portion 76 which is formed by etching the substrate 62, a convex portion 77 which is the part remained where has been covered with the metal thin film 68, and convex portions 78 which are the part remained where have been covered with the dots 74 as shown in
Next, a base member (unshown in the drawings) used for manufacturing a stamp 10a is prepared. Referring to
Referring to
The method for manufacturing the stamp described in Example 1 can also be apply to the manufacturing of a stamp having a micron-level resolution.
According, to the method for manufacturing the stamp described in Example 2, the interferometric lithography technique which does not require a mask and can perform an exposure for a shorter time period is used. Therefore, it is possible to manufacture the stamp having nano or submicron scale-lattice, dots, holes and the like formed in a relatively large area at a lower cost compared with the method of Example 1.
E. Electronic Apparatus
Referring to
In this case, the dots which are formed on the object face 24 corresponding to the plurality of the apical faces 14a are arranged such that a dot in a line faces a gap between two adjacent dots in the next line. Thereby, even if the functional liquid flows over the gap between the dots in one line, the dot in the next line can prevent the functional liquid from further flowing. Therefore, with the surface energy difference bank in which the dots are arranged in this way, it is possible to effectively prevent the flowing out of the functional liquid across the dots.
Though the O2 plasma treatment or the CF4 plasma treatment is performed as a surface treatment in the above-described embodiments, a corona discharge treatment, an UV ozone treatment, a chemical reaction treatment, coating, a vacuum deposition or the like can be performed as the surface treatment instead of the plasma treatment.
In the process of the formation of the lower electrode 22, the PMMA layer is embossed by using the silicon chip having a plurality of grooves in order to form the plurality of the grooves according to the above-described embodiments. However, photolithography, an interferometric lithography, a micro-contact printing, an off-set printing or the like can be performed instead of the embossing.
Though the ink-jet printing method is adopted to form the lower electrodes 22 in the above-described embodiments, a resist patterning and lift-off method, an electroless plating method, a micro-cutting method, a micro/nano-probe writing method or the like con be adopted instead of the ink-jet printing method.
Either a solution or a colloidal suspension can be used as the material which is printed by the ink-jet printing method. Either an organic material or an inorganic material can be used as the conductive material. For example, polyethylenedioxy thiophene (PEDOT), polyaniline, gold, nickel, copper, carbon or the like can be used.
The above-described manufacturing methods can be applied to either a “sheet-to-sheet method” or a “roll-to-roll method”. The material for forming the substrate can be flexible or solid. For example, polyethylene-naphthalate (PEN), polyethylene terephthalate (PET), poly-carbonate (PC), poly-ethersulphone (PES), polyetherketone (PEEK: registered trademark) or the like can be used as the material of the substrate.
The invention is obviously not limited to the specific embodiments described herein, but also encompasses any variations that may be considered by any person skilled in the art, within the general scope of the invention. Note that the invention encompasses the substantially same elements and components as those described in the above-described embodiments (for example, a structure resulting in the same function, method or effect, or a structure having the same purpose or result). The invention also encompasses the structure in which unessential part of the structure described in the above embodiments is replaced by other element. The invention also encompasses the constructions that serve the equivalent function and exert the equivalent effect and the constructions that can achieve the same objective as those of the embodiments. The invention also encompasses the structure in which a hitherto know art is added to the structure described in the above embodiments.
The entire disclosure of Japanese Patent Application No. 2006-195190, filed Jul. 18, 2006, is expressly incorporated by reference herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-195190 | Jul 2006 | JP | national |
