JP2009105329A - Formation method of metal thin film, metal thin film, and method of manufacturing thin-film transistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a metal thin film capable of easily forming an inclined plane in a simple process, and to provide the metal thin film and a method of manufacturing a thin-film transistor. <P>SOLUTION: A first base layer 13A containing a catalyst material is formed on a substrate 11, and then an electroless plating treatment is performed on it to form a first plating layer 14A so as to coat the first base layer 13A. Then, a second base layer 13B containing a catalyst material is formed in a neighborhood region of the first plating layer 14A on the substrate 11, and further a second electroless plating treatment is performed with the second base layer 13B and the first plating layer 14A as catalysts. A second plating layer 14B is so film-formed as to coat the first plating layer 14A, accumulated on the first base layer 13A, and the second base layer 13B. By the difference of film thickness caused between a region facing the first base layer 13A and a region facing the second base layer 13B, a taper 14A-1 is formed at the end portion of the metal thin film 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for forming a metal thin film using an electroless plating method, a metal thin film formed thereby, and a method for manufacturing a thin film transistor.

  Conventionally, in the process of manufacturing a semiconductor circuit such as a thin film transistor (TFT), a metal thin film such as a wiring is formed by a vacuum deposition method, a sputtering method, etc., and then a photolithography method which is one of microfabrication techniques. Thus, patterning is formed. The photolithography method, for example, obtains a desired pattern by applying a photoresist material using a photosensitive material or the like on a metal thin film and then stripping the photoresist through steps of exposure, development, washing, and etching. Is the method.

  In such a metal thin film, for example, if there is a step at the end of its cross-sectional shape, when another layer is formed thereon to form a multilayer structure, the step coverage deteriorates due to the step. For this reason, there is a possibility that the film laminated on the metal thin film may be disconnected. Therefore, in the process of forming the metal thin film, it is important to form an inclined surface at the end of the cross-sectional shape.

  Therefore, Patent Documents 1 and 2 propose a method in which the resist shape is controlled by adjusting the baking temperature of the patterned metal resist, and an inclined surface is formed in the cross-sectional shape of the metal thin film in the subsequent dry etching process. . Alternatively, Patent Documents 3 and 4 describe a technique in which a metal thin film is formed in two layers and an inclined surface is formed in the cross-sectional shape of the metal thin film by wet etching.

On the other hand, as a method for forming a metal thin film, in addition to the vacuum deposition method and the sputtering method, an ink jet method using metal fine particles and metal paste described in Patent Document 5 and Non-Patent Documents 1 and 2 can be used. A screen printing method or an electroless plating method (for example, Patent Documents 6 and 7) can be used. For example, in the technique of Patent Document 6, when forming a metal wiring of an active matrix substrate such as a liquid crystal display device, an electroless plating process is performed so as to cover a base layer on which an inclined surface is formed. Inclined surfaces are formed at both ends. Further, Patent Document 7 describes a method for forming a functional thin film that leads to resource saving and energy saving using a combination of an inkjet method and an electroless plating method.
Japanese Patent No. 3324730 Japanese Patent No. 3574270 Japanese Patent No. 2614403 JP-A-1-151236 Japanese Patent No. 3774638 Japanese Patent No. 3567142 JP 2001-288578 A "Printing technology on flexible substrates-Electronic device manufacturing technology using Roll to Roll-"; Toray Research Center, pp.125-126 (2006): [Original literature] Kenzo Hatada; "Micropatterning technology using metal nanopaste" , Journal of the Imaging Society of Japan, Vol.42, No.3, pp.238-244 (2003) Mizaki et al .; "Current status of wiring technology development using inkjet method", Journal of Japan Institute of Electronics Packaging, Vol.9, No.7, pp.546-549 (2006) Hidber et al .; Langmuir, vol.12, p.1375 (1996)

  However, as described above, there is a problem that the number of steps increases when the inclined surface is patterned by photolithography after forming a metal thin film using a vacuum deposition method or a sputtering method.

  Therefore, in order to reduce the number of processes, a method of patterning the metal thin film by one electroless plating process can be considered. However, in the electroless plating treatment, there is a problem that it is difficult to obtain a desired cross-sectional shape because a metal thin film is usually deposited using a catalyst as a nucleus. Further, according to the method of Patent Document 6, although the inclined surface can be formed by using electroless plating treatment, it is necessary to form the inclined surface by using a method such as etching on the base layer of electroless plating. Therefore, it was not enough as a solution to the above problem.

  The present invention has been made in view of such a problem, and an object of the present invention is to form a metal thin film capable of easily forming an inclined surface by a simple process, and to manufacture a metal thin film and a thin film transistor formed thereby. It is to provide a method.

  The method for forming a metal thin film according to the present invention includes a step of forming a first underlayer containing a first catalyst material in a region on a substrate, and a first electroless process using the first underlayer as a catalyst. A step of forming a first plating layer by performing a plating process; a step of forming a second underlayer containing a second catalyst material in a region in the vicinity of the first plating layer on the substrate; A step of forming a second plating layer by performing a second electroless plating process using the second underlayer and the first plating layer as a catalyst.

  The method of manufacturing a thin film transistor of the present invention includes an electrode forming step of forming at least one of the first electrode, the second electrode, and the third electrode on the substrate using an electroless plating process. This electrode forming step includes each step of the metal thin film forming method of the present invention.

  The metal thin film of the present invention is provided in one region on the substrate, and includes a first underlayer containing a first catalyst material, a first plating layer formed so as to cover the first underlayer, Provided in a region in the vicinity of the first plating layer on the substrate, formed so as to cover the second underlayer containing the second catalyst material, the first plating layer and the second underlayer; And a second plating layer having an inclined surface in the end region.

  In the method for forming a metal thin film and the method for manufacturing a thin film transistor of the present invention, the first base layer is covered by applying a first electroless plating process using the first base layer containing the first catalyst material as a catalyst. Thus, the first plating layer is formed. Thereafter, a second underlayer containing the second catalyst material is formed in a region in the vicinity of the first plating layer on the substrate, and the second underlayer and the first plating layer are used as a catalyst to form the second underlayer. The electroless plating process 2 is performed so as to cover the first plating layer formed on the first base layer and the second base layer formed in the vicinity of the first plating layer. In addition, a second plating layer is formed. At this time, since the first plating layer is deposited on the first underlayer, a film is formed between the region facing the first underlayer and the region facing the second underlayer. A thickness difference occurs.

  According to the method for forming a metal thin film of the present invention, since the first electroless plating process is performed using the first underlayer containing the first catalyst material as a catalyst, the first underlayer is covered. A first plating layer can be formed on the substrate. Thereafter, a second underlayer containing the second catalyst material is formed in a region in the vicinity of the first plating layer on the substrate, and the second underlayer and the first plating layer are used as a catalyst to form the second underlayer. Since the second electroless plating process is performed, the second plating layer can be formed so as to cover the first plating layer and the second underlayer. Thereby, a film thickness difference is generated between the region facing the first base layer and the region facing the second base layer, and an inclined surface can be formed on the metal thin film. Therefore, the inclined surface can be easily formed by a simple process without performing a process such as etching using a photoresist after the film formation.

  According to the thin film transistor manufacturing method of the present invention, at least one of the first electrode, the second electrode, and the third electrode is formed on the substrate using the metal thin film forming method of the present invention. Since it did in this way, an inclined surface can be formed in an electrode with a simple process, and generation | occurrence | production of a leakage current etc. can be suppressed by this.

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

  FIG. 1 shows a cross-sectional configuration of a metal thin film 10 according to an embodiment of the present invention.

  The metal thin film 10 is formed using an electroless plating method to be described later, and is formed on the substrate 11 via the adhesion layer 12, for example. The metal thin film 10 includes a first base layer 13A, a second base layer 13B, a first plating layer 14A, and a second plating layer 14B, and a taper (inclined surface) 14B-1 is formed in the end region. Yes. The metal thin film 10 is, for example, an electrode or a wiring on a circuit board, and the thickness of the electrode or the wiring is determined by the width W of the metal thin film 10.

  The substrate 11 is made of a material such as silicon, synthetic quartz, glass, metal, resin, or resin film, for example.

  The adhesion layer 12 enhances the adhesion of the first foundation layer 13A and the second foundation layer 13B to the substrate 11. The constituent material of the adhesion layer 12 includes a silane coupling agent such as an amino silane compound, a mercapto silane compound, a phenyl silane compound, and an alkyl silane compound. What is necessary is just to select an appropriate thing according to the material which comprises 13 A of 1st base layers, the 2nd base layer 13B, and the board | substrate 11. FIG. As the silane coupling agent, for example, KBM-603 (N-2 (aminoethyl) 3-aminopropyltrimethoxysilane) (trade name) manufactured by Shin-Etsu Chemical Co., Ltd. can be used.

  The first base layer 13A is provided in a selective region on the substrate 11 with a thickness of, for example, several nm to several tens of nm, and is formed with a width smaller than the width W of the entire metal thin film 10. The second foundation layer 13B is formed in the vicinity of the first plating layer 14A on the substrate 11 with a thickness of, for example, several nm to several tens of nm and a width x. Each of the first underlayer 13A and the second underlayer 13B is made of a catalyst material for electroless plating treatment described later, such as palladium (Pd), gold (Au), platinum (Pt), silver (Ag), etc. It is configured to include at least one kind.

  14 A of 1st plating layers are formed so that 13 A of 1st base layers may be covered, for example, thickness is several dozen nm-100 nm. The second plating layer 14B is formed so as to cover the first plating layer 14A formed on the first base layer 13A and the second base layer 13B, and has a thickness of, for example, 100 nm. The first plating layer 14A and the second plating layer 14B are plating films that are deposited by an electroless plating process, which will be described later. The second plating layer 14B is deposited using the first plating layer 14A as a catalyst. This is a so-called autocatalytic plating film.

  Examples of the autocatalytic electroless plating material constituting the first plating layer 14A and the second plating layer 14B include nickel (Ni), copper (Cu), gold (Au), silver (Ag), and palladium. A single metal such as (Pd), cobalt (Co), platinum (Pt), indium (In), tin (Sn), or rhodium (Rh) can be used. In addition, metals that can be co-deposited with these metals, such as phosphorus (P), boron (B), chromium (Cr), manganese (Mn), iron (Fe), zinc (Zn), molybdenum (Mo), cadmium (Cd), tungsten (W), rhenium (Re), titanium (Ti), sulfur (S), vanadium (V), or the like may be further used.

  However, the constituent materials of the first plating layer 14A and the second plating layer 14B are appropriately selected according to the relationship with the constituent materials of the first base layer 13A and the second base layer 13B that function as a catalyst for the electroless plating process. It is.

Moreover, the structure of such a metal thin film 10 can be easily specified by any of the following methods (1) to (5).
(1) The cross section of the metal thin film 10 is observed with, for example, a transmission electron microscope (TEM), and a catalyst material (first base layer 13A and second base layer 13B) for electroless plating is detected.
(2) Whether or not the metal thin film 10 contains a eutectable metal is detected by, for example, SIMS (Secondary Ion-microprobe Mass Spectrometer), X-ray photoelectron spectroscopy (XPS), or the like. For example, in the case where the first plating layer 14A and the second plating layer 14B are configured to include nickel, it is detected whether or not boron or phosphorus is included in addition to this.
(3) Whether or not an additive such as an organic compound used in the electroless plating process is contained in the metal thin film 10 is detected by SIMS, for example.
(4) The cross-sectional shape of the metal thin film is observed with, for example, a scanning electron microscope (SEM).
(5) The roughness of the surface is observed with, for example, an atomic force microscope (AFM) or a stylus. However, evaluation is difficult when any surface treatment is performed after the electroless plating treatment.

  Next, a method for forming the metal thin film 10 as described above will be described with reference to FIGS. 2-5 is sectional drawing which showed the formation method of the metal thin film 10 in order of a process.

(1. Cleaning of substrate 11)
First, as shown in FIG. 2A, the substrate 11 made of the above-described material is washed with an alkaline solution, then washed with pure water and dried. Further, the surface of the substrate 11 is subjected to UV ozone treatment to remove organic substances on the surface.

(2. Formation of adhesion layer 12)
Subsequently, as illustrated in FIG. 2B, the adhesion layer 12 is formed over the substrate 11. For example, the adhesion layer 12 is formed on the surface of the substrate 11 by performing a surface treatment by a vapor phase method or a spin coating method using a silane coupling agent made of the above-described material. When the spin coating method is used, the silane coupling agent is diluted with a solvent and used, and after the treatment, it is preferably heated to 120 ° C. for 5 minutes or more in the atmosphere.

(3. Formation of the first underlayer 13A)
Next, the pattern of the first base layer 13A is printed on the substrate 11 on which the adhesion layer 12 is formed, for example, by the μ contact method (see Non-Patent Document 3). In this μ contact printing method, pattern printing is performed using a transfer plate on which an uneven pattern such as a stamp is formed. In the present embodiment, two types of stamps corresponding to the patterns of the first base layer 13A and the second base layer 13B described later are produced.

(3-1. Production of stamp 110)
First, the stamp 110 is manufactured by pouring the material of the stamp 110 into a stamp mold 200 as shown in FIG. The stamp mold 200 includes a substrate 201 on which a concavo-convex pattern 201A is formed, a substrate 203 disposed so as to face the concavo-convex pattern 201A, and a spacer 202 provided between the substrate 201 and the substrate 203. It is configured. As the substrate 201, for example, a glass substrate can be used. The uneven pattern 201A can be formed on the surface of the substrate 201 by, for example, a photolithography method. As the substrate 203, glass, Teflon (registered trademark), or the like can be used. Further, as a material of the stamp 110, a material that is cured by a polymerization reaction by mixing two liquids, for example, polydimethylsiloxane (PDMS), specifically, SYLGARD 184 (trade name) manufactured by Toray Dow Corning Silicone Co., Ltd. is used. be able to.

  Specifically, after mixing two liquids of the material of the stamp 110 into the stamp mold 200 as described above, the mixture is poured by stirring and defoaming. At this time, the stamp 110 is adjusted to a desired thickness by the spacer 202 of the stamp mold 200. Subsequently, after heating and polymerizing in a constant temperature bath at 60 ° C. for 12 hours, the substrate 201 and the substrate 203 of the stamp mold 200 are separated to have a printed pattern 110A as shown in FIG. The stamp 110 can be made. The uneven pattern 201A of the stamp mold 200 forms the print pattern 110A of the stamp 110.

(3-2. Formation of catalyst layer 13A-1 on stamp 110)
Next, as shown in FIG. 4A, the catalyst layer 13A-1 to be the first underlayer 13A is formed on the side of the stamp 110 on which the printed pattern 110A is formed.

  First, the catalyst material is applied to the stamp 110 by immersing the printed pattern 110A side of the stamp 110 in a catalyst applying agent containing a catalyst material for electroless plating for several seconds to several minutes. As the catalyst imparting agent, for example, a palladium catalyst imparting agent (OPC50 inducer: trade name) manufactured by Okuno Pharmaceutical Co., Ltd. can be used. This is a mixed solution of two products and has a recommended method of use. However, if the life of the solution is not considered, the pH may be adjusted in consideration of damage to the plating layer. The catalyst-imparting agent is not limited to the above-described one, and a solution containing a catalyst material, such as a palladium chloride solution, may be used.

  Thereafter, the catalyst material applied to the stamp 110 is blown with nitrogen to dry the surface, thereby forming the catalyst layer 13A-1 on the stamp 110.

(3-3. Transfer of catalyst layer 13A-1)
Next, the catalyst layer 13A-1 is transferred to the substrate 11 on which the adhesion layer 12 is formed. At this time, first, as shown in FIG. 4A, the catalyst formed on the stamp 110 on the surface of the substrate 11 on which the adhesion layer 12 is formed by the same method as the known relief printing method. Layer 13A-1 is contacted. At this time, care should be taken that only the convex surface (upper bottom surface) 130 of the stamp 110 is in contact with the adhesion layer 12 and the other part (concave portion) is not in contact. This is because a desired pattern cannot be obtained if the recess comes into contact. Subsequently, the contact layer 12 and the catalyst layer 13A-1 on the convex surface 130 of the stamp 110 are kept in contact with each other for several seconds to several minutes.

  Subsequently, as shown in FIG. 4B, when the stamp 110 is removed from the substrate 11, only the catalyst layer 13 </ b> A- 1 formed on the convex surface 130 of the stamp 110 moves toward the adhesion layer 12 on the substrate 11. Transcribed.

  After that, the substrate 11 on which the catalyst layer 13A-1 is pattern-transferred is heated in the atmosphere at a temperature of 100 ° C. to 150 ° C., so that the adhesion of the transferred catalyst layer 13A-1 to the substrate 11 is strengthened. . Thereby, the pattern of the first base layer 13 </ b> A can be printed on the adhesion layer 12 of the substrate 11. 2 to 4 and these descriptions, a plurality of first underlayers 13A are patterned, but the region S shown in FIG. 4 has the configuration shown in FIGS. It corresponds.

(4. Electroless Plating Treatment—Formation of First Plating Layer 14A)
Next, as shown in FIG. 5A, the first electroless plating process is performed on the substrate 11 on which the first base layer 13A is formed, thereby forming the first plating layer 14A. As the plating solution, for example, when nickel is deposited as a plating film, Ni-B film-forming plating solution BEL-801 (trade name) manufactured by Uemura Kogyo Co., Ltd. can be used. The temperature of the plating bath is, for example, 60 ° C., and the immersion time is appropriately set depending on the desired film thickness. Further, the film forming rate is set to 200 nm / min, for example. The first electroless plating process corresponds to the first electroless plating process of the present invention.

(5. Formation of second underlayer 13B)
Next, as shown in FIG. 5B, a second underlayer 13B is formed in a region in the vicinity of the formed first plating layer 14A. At this time, the second underlayer 13B is printed in a desired region by using the μ contact printing method as in the case of the first underlayer 13A described above. However, since the printing pattern is different from that of the first underlayer 13A, a stamp for the pattern of the second underlayer 13B is newly produced.

(6. Electroless plating treatment-formation of second plating layer 14B)
Finally, a second electroless plating process is performed on the substrate 11 on which the first plating layer 14A and the second base layer 13B are formed by the same procedure as described above, thereby forming the second plating layer 14B. To do. At this time, it is preferable to immerse the substrate 11 in the plating bath after warming the substrate 11 with warm water having the same temperature as the plating bath. Thereby, it can prevent that a plating film peels by the stress of the formed plating film. The same applies when the electroless plating process is performed three times or more. Thus, the metal thin film 10 shown in FIG. 1 is formed. Note that the second electroless plating treatment corresponds to the second electroless plating treatment of the present invention.

  Thus, in the formation method of the metal thin film 10 of this Embodiment, the electroless plating process is performed on the substrate 11 on which the first base layer 13A containing the electroless plating catalyst material is formed. First plating layer 14A is formed to cover base layer 13A.

  Next, after the second underlayer 13B is formed in the vicinity of the first plating layer 14A on the substrate 11, an electroless plating process is performed using the second underlayer 13B and the first plating layer 14A as a catalyst. A plating film is deposited using the second underlayer 13B and the first plating layer 14A deposited on the first underlayer 13A as nuclei. Therefore, the second plating layer 14B is formed so as to cover the first plating layer 14A deposited on the first foundation layer 13A and the second foundation layer 13B formed in the vicinity of the first plating layer 14A. . At this time, since the first plating layer 14A is deposited on the first base layer 13A, a film is formed between the region facing the first base layer 13A and the region facing the second base layer 13B. A thickness difference occurs.

  As described above, according to the method for forming the metal thin film 10 of the present embodiment, the electroless plating process is performed using the first underlayer 13A formed on the substrate as a catalyst, and the first underlayer 13A is covered so as to cover the first underlayer 13A. After forming the first plating layer 14A, the second underlayer 13B is formed in the vicinity of the first plating layer 14A, and the electroless plating process is performed using the second underlayer 13B and the first plating layer 14A as a catalyst. Therefore, the second plating layer 14B can be formed so as to cover the first plating layer 14A and the second foundation layer 13B deposited on the first foundation layer 13A. Therefore, a film thickness difference is generated between the region facing the first base layer 13A and the region facing the second base layer 13B, and the taper 14A-1 can be formed in the end region of the metal thin film 10.

  Here, in the taper formation using the conventional photolithography method, it is necessary to go through a process such as etching using a photoresist after forming a metal thin film by a vacuum evaporation method or the like, which increases the number of processes. End up.

  FIG. 10A shows a photograph of a cross section of a metal thin film (dotted line portion in the drawing) in which a chromium (Cr) film is deposited by vacuum deposition and then tapered by wet etching. As described above, when the taper is formed by wet etching, the etching is isotropic, so the taper portion is not linear, and in particular, the edge of the upper surface of the metal thin film has an angle close to perpendicular to the substrate surface. Become. In this case, if another layer is laminated on the formed metal thin film, the uniformity of the thickness of the other layer is deteriorated, so that disconnection is likely to occur. Note that FIG. 10B shows a schematic diagram of a cross-sectional shape of a metal thin film when taper is formed by dry etching. As described above, when the taper is formed by dry etching, the taper portion is linear because the receding of the mask such as a resist is used. However, as described above, the number of processes increases.

  Therefore, in order to reduce the number of processes, it is considered that a metal thin film is formed by one electroless plating process. However, since a plating film is usually deposited with a catalyst as a nucleus, one electroless plating is performed. In processing, it is difficult to obtain a desired tapered shape.

  In contrast, in the present embodiment, the electroless plating process is performed a plurality of times, so that the taper shape of the metal thin film is tapered by a full additive method using the electroless plating process without passing through a process such as etching. Formation is possible. For this reason, the patterning process after film-forming becomes unnecessary. Therefore, the taper can be easily formed by a simple process.

  Further, the ratio of the width x of the second underlayer 13B to the entire width W of the metal thin film 10, the thickness of the first underlayer 13A, the second underlayer 13B, the first plating layer 14A, the second plating layer 14B, and the like are appropriately set. By doing so, a desired taper shape can be easily formed in accordance with the specifications of the wiring and electrode. Further, in the present embodiment, the case where the electroless plating process is performed twice has been described. However, if the electroless plating process is performed three times or more by the same procedure, the taper shape is more densely formed. It is possible.

  Next, a method for manufacturing the thin film transistor 1 using such a method for forming the metal thin film 10 will be described with reference to FIGS. 6 to 8 are cross-sectional views illustrating the method of manufacturing the thin film transistor 1 in the order of steps.

  First, as shown in FIG. 6A, the buffer layer 16 is formed on the substrate 15 made of glass or the like by, for example, vapor deposition or sputtering. After that, as shown in FIG. 6B, the gate electrode 10a as the metal thin film 10 of the present embodiment is formed on the buffer layer 16 by the above-described forming method. At this time, for example, a catalyst material containing palladium can be used as the first base layer 13A and the second base layer 13B, and the first plating layer 14A and the second plating layer 14B are, for example, plating films containing nickel. . Subsequently, as shown in FIG. 6C, a gate insulating film 17 is formed by, for example, a vapor deposition method or a sputtering method so as to cover the formed gate electrode 10a.

  Next, as shown in FIG. 7A, an α-Si (amorphous silicon) (n +) layer 18 and an α-Si (i) layer 19 are formed in this order on the formed gate insulating film 17. To do. Subsequently, as shown in FIG. 7B, the formed α-Si (n +) layer 18 and α-Si (i) layer 19 are formed by patterning, for example, by a dry etching method. Subsequently, as shown in FIG. 7C, the source as the metal thin film 10 of the present embodiment so as to cover the α-Si (n +) layer 18 and the α-Si (i) layer 19 formed by patterning. The electrode 10b and the drain electrode 10c are formed by the above-described forming method. The source electrode 10b and the drain electrode 10c can be made of the same material as the gate electrode 10a.

  Next, as shown in FIG. 8A, the surfaces of the α-Si (n +) layer 18 and the α-Si (i) layer 19 are removed by, for example, dry etching, and then shown in FIG. 8B. As described above, the passivation film 20 is formed so as to cover the source electrode 10b and the drain electrode 10c. Subsequently, a contact hole 20 a is formed in the formed passivation film 20. Thus, the thin film transistor 1 is completed.

  As described above, in the method for manufacturing the thin film transistor 1, the gate electrode 10a, the source electrode 10b, and the drain electrode 10c are formed by the method for forming the metal thin film 10 of the present embodiment, so that the end of each electrode is easily tapered. Can be formed. Here, conventionally, in order to form a desired tapered shape, it has been necessary to perform a process such as etching after forming a metal thin film to be an electrode by an evaporation method or the like. On the other hand, in the present embodiment, electrodes can be formed by a full additive method using electroless plating, so that a patterning step after film formation is not necessary.

  Further, by forming a desired taper shape on each electrode, it is possible to suppress the occurrence of leakage current and the like.

  Note that the gate electrode 10a, the source electrode 10b, and the drain electrode 10c in the present embodiment correspond to the first to third electrodes of the present invention.

(Example)
Next, examples of the method for forming the metal thin film 10 of the present embodiment will be described.

  As an example, the metal thin film 10 was formed by the method shown in FIGS. At this time, an amino silane coupling agent (KBM-603: trade name) manufactured by Shin-Etsu Chemical Co., Ltd. is used as an adhesion layer 12 on a substrate 11 made of glass, and Toray Dow Corning Silicone is used as a stamp material. SYLGARD 184 (trade name) manufactured by the company was used. Further, as a catalyst imparting agent for the stamp, a palladium catalyst imparting agent (OPC50 inducer: trade name) manufactured by Okuno Pharmaceutical Co., Ltd. is used to attach the first base layer 13A and the second base layer 13B onto the adhesion layer 12. Printed on each. In addition, for the electroless plating treatment of the first plating layer 14A and the second plating layer 14B, Ni-B film-forming plating solution BEL-801 (trade name) manufactured by Uemura Kogyo Co., Ltd. is used to change the temperature of the plating bath. The temperature was 60 ° C., the immersion time was 30 seconds, the film formation rate was 200 nm / min, and the desired width (thickness) W was 50 μm. Note that the first and second electroless plating processes were performed under the same conditions.

  FIG. 9A shows the cross-sectional shape of the end portion of the metal thin film 10 formed as described above. Further, as a comparative example of the above-described embodiment, FIG. 9B shows a cross-sectional shape of an end portion of a metal thin film formed by one electroless plating process. In the comparative example, after forming an underlayer containing the same catalyst material as in the above example, the entire metal thin film has a width W due to the same plating material, plating bath, and film formation rate as in the above example. An electroless plating process was performed.

  Here, as shown in FIG. 9B, when a metal thin film is formed so as to have a desired width W by one electroless plating process, the end becomes steep and a large step is generated. For this reason, when another layer is formed on the formed metal thin film to form a multilayer structure, the step coverage is deteriorated due to the step at the end of the metal thin film. Therefore, there is a possibility that the film laminated on the metal thin film may be broken.

  On the other hand, as shown in FIG. 9A, when a metal thin film is formed so as to have a desired width W by two electroless plating processes, the end portion becomes loose, as in the above comparative example. No problems arise. Therefore, after forming the first plating layer 14A on the first underlayer 13A by electroless plating, the second underlayer 13B is formed in the vicinity of the first plating layer 14A. It was shown that a desired taper shape can be easily formed at the end of the metal thin film 10 by further performing electroless plating using the 1 plating layer 14A as a catalyst.

  Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to these embodiments and the like, and various modifications are possible.

  For example, in the above embodiment and the like, the second underlayer 13B having the same width (x) is formed on both sides of the first plating layer 14A formed by the first electroless plating process, and the both ends of the metal thin film 10 are formed. The case where the taper 14A-1 is formed has been described as an example. However, the present invention is not limited to this, and the number, position, width, shape, inclination angle, and the like of the taper are appropriately set according to the required pattern. is there. For example, the second underlayer 13B may be formed only on the first plating layer 14A side, and the taper 14A-1 may be formed at one end of the metal thin film 10. Moreover, you may form so that the width | variety and inclination angle of a taper may differ on both sides of the metal thin film 10, respectively.

  In addition to the thin film transistor as described above, the metal thin film formed according to the present invention can be applied to an electronic device using a metal electrode, such as a capacitor.

  Furthermore, the material and thickness of each component described in the above embodiments and the like, or the film formation method and film formation conditions are not limited, and other materials and thicknesses may be used. Alternatively, film forming conditions may be used.

It is sectional drawing showing the metal thin film which concerns on one embodiment of this invention. It is sectional drawing showing the formation method of the metal thin film shown in FIG. 1 in order of a process. FIG. 3 is a cross-sectional view illustrating a process following FIG. 2. FIG. 4 is a cross-sectional view illustrating a process following FIG. 3. FIG. 5 is a cross-sectional view illustrating a process following FIG. 4. It is sectional drawing represented to the manufacturing method process order of the thin-film transistor which concerns on one embodiment of this invention. FIG. 7 is a cross-sectional view illustrating a process following FIG. 6. FIG. 8 is a cross-sectional diagram illustrating a process following the process in FIG. 7. There is a result of analyzing the cross-sectional shape of the metal thin film. FIG. (A) shows an example and FIG. (B) shows a comparative example. It is sectional drawing showing the taper shape formed using the conventional vacuum evaporation method and the photoresist method.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Thin film transistor, 10 ... Metal thin film, 10a ... Gate electrode, 10b ... Source electrode, 10c ... Drain electrode, 11, 15 ... Substrate, 12 ... Adhesion layer, 13A ... 1st foundation layer, 13B ... 2nd foundation layer, 14A ... 1st plating layer, 14B ... 2nd plating layer, 14B-1 ... Taper, 16 ... Buffer layer, 17 gate insulating film, 18 ... α-Si (n +) layer, 19 ... α-Si (i) layer, 20 ... passivation film.

Claims (3)

Forming a first underlayer containing a first catalyst material in a region on a substrate;
Forming a first plating layer by applying a first electroless plating treatment using the first underlayer as a catalyst;
Forming a second underlayer containing a second catalyst material in a region in the vicinity of the first plating layer on the substrate;
Forming a second plating layer by performing a second electroless plating process using the second underlayer and the first plating layer as a catalyst. Method. A method of manufacturing a thin film transistor including a multilayer film including a first electrode, a second electrode, and a third electrode on a substrate,
Including an electrode forming step of forming at least one of the first to third electrodes using an electroless plating process;
The electrode forming step includes
Forming a first underlayer containing a first catalyst material in a region on a substrate;
Forming a first plating layer by applying a first electroless plating treatment using the first underlayer as a catalyst;
Forming a second underlayer containing a second catalyst material in a region in the vicinity of the first plating layer on the substrate;
And a step of forming a second plating layer by performing a second electroless plating process using the second underlayer and the first plating layer as a catalyst. . A first underlayer provided in a region on the substrate and including a first catalyst material;
A first plating layer formed to cover the first underlayer;
A second underlayer provided in a region in the vicinity of the first plating layer on the substrate and containing a second catalyst material;
A metal thin film comprising: a second plating layer formed so as to cover the first plating layer and the second base layer and having an inclined surface in an end region.

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