JP2009102720A - Method for forming metal thin film, metal thin film, and method for producing thin film transistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a metal thin film which can easily form a tilted face by a simple process, to provide a metal thin film, and to provide a method for producing a thin film transistor. <P>SOLUTION: A first substrate layer 13A including a catalyst material for electroless plating treatment is formed in a first region D1 and a second region D2 on a substrate 11, and thereafter, a second substrate layer 13B is formed in a region corresponding to the first region D1 on the first substrate layer 13A. The concentration distribution of the catalyst material for electroless plating treatment is made higher than that of the second region D2 in the first region D1. Thus, by applying electroless plating treatment to the substrate 11 in which the first substrate layer 13A and the second substrate layer 13B are formed, the film deposition rate in the first region D1 is made higher than that in the second region D2. <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 layer 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 layer 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 layer in the subsequent dry etching process. . Alternatively, Patent Documents 3 and 4 describe a technique in which a metal layer is formed in two layers and an inclined surface is formed in the cross-sectional shape of the metal layer by wet etching.

On the other hand, as a method for forming a metal layer, in addition to the above-described vacuum deposition method and sputtering method, an inkjet method using metal fine particles and a 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. Tapers 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 or the like after the metal layer is formed by vacuum deposition or sputtering.

  Therefore, in order to reduce the number of steps, a method of patterning the metal layer by electroless plating can be considered. However, in the electroless plating treatment, there is a problem that it is difficult to form a desired inclined surface because the 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 base layer containing a catalyst material for electroless plating in a first region on a substrate and a second region in the vicinity of the first region, Forming a plating layer by subjecting the substrate on which the base layer is formed to electroless plating using the base layer as a catalyst, and the base layer has a higher concentration distribution of the catalyst material in the first region than in the second region. It forms so that it may become.

  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 is provided in a first base layer containing a catalyst material for the electroless plating process, and in a central region on the first base layer. The second underlayer containing the catalyst material and a plating layer formed so as to cover the first and second underlayers and 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, an underlayer is provided in the first region on the substrate and the second region in the vicinity thereof, and the concentration distribution of the catalyst material is higher in the first region than in the second region. After the film is formed so as to be higher, the electroless plating treatment is performed, so that the film formation rate is higher in the first region on the substrate than in the second region. Therefore, an inclined surface is formed in the end region of the plating layer to be formed.

  According to the method for forming a metal thin film and the method for manufacturing a thin film transistor of the present invention, an underlayer containing a catalyst material for electroless plating treatment is formed on the first region on the substrate and the second region in the vicinity thereof. Since the concentration distribution is formed in the first region so as to be higher than that in the second region, and the electroless plating process is performed, the film formation rate is higher in the first region on the substrate than in the second region, An inclined surface can be formed in the end region of the plating layer. Accordingly, 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.

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

[First Embodiment]
FIG. 1 shows a cross-sectional configuration of a metal thin film 10 according to the first embodiment of the present invention.

  The metal thin film 10 is formed by using an electroless plating method to be described later, and is provided 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, and a plating layer 14, and a taper (inclined surface) 14-1 is formed in the end region. 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 the first region D1 (the central region of the metal thin film 10) on the substrate 11, for example, with a thickness of several nm to several tens of nm. The second underlayer 13B is formed in a region corresponding to the first region D1 on the first underlayer 13A, for example, with a thickness of several nanometers to several tens of nanometers. Each of the first base layer 13A and the second base layer 13B is at least one of catalyst materials for electroless plating treatment described later, such as palladium (Pd), gold (Au), platinum (Pt), silver (Ag), and the like. Consists of seeds.

  In the present embodiment, the first underlayer 13A and the second underlayer 13B contain the same catalyst material at the same concentration. Thus, the first region D1 has a two-layer structure of the first base layer 13A and the second base layer 13B, and the second region D2 has a single-layer structure of the first base layer 13A. Accordingly, the concentration distribution of the catalyst material for the electroless plating process is higher in the first region D1 on the substrate 11 than in the second region D2.

  The plating layer 14 is formed so as to cover the first base layer 13A and the second base layer 13B over the entire surface of the first region D1 and the second region D2. The plating layer 14 has a thickness of, for example, several tens nm to several hundreds nm, and is formed by being deposited by an electroless plating process described later.

  Examples of the material constituting the plating layer 14 include materials that can be deposited by electroless plating, such as nickel (Ni), copper (Cu), gold (Au), silver (Ag), palladium (Pd), A simple metal such as 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 material of the plating layer 14 is appropriately selected depending on the relationship with the catalyst material contained in the first underlayer 13A and the second underlayer 13B.

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 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. ing. For example, a glass substrate is used as the substrate 201. 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 surface of the substrate 11 on which the adhesion layer 12 was formed was formed on the stamp 110 by a method similar to a known relief printing method or the like. The catalyst layer 13A-1 is brought into contact. 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 first underlayer 13A can be formed on the adhesion layer 12 of the substrate 11 (FIG. 5A). 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. Formation of second underlayer 13B)
Next, as shown in FIG. 5B, the second underlayer 13B is formed in a region corresponding to the first region D1 on the formed first underlayer 13A. At this time, the second underlayer 13B is printed by 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.

(4. Electroless plating treatment)
Finally, the plating layer 14 is formed by performing an electroless plating process on the substrate 11 on which the first base layer 13A and the second base layer 13B are formed. In this case, 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. Thus, the metal thin film 10 shown in FIG. 1 can be formed.

  As described above, in the method for forming the metal thin film 10 according to the present embodiment, the first base layer 13A is formed over the first region D1 and the second region D2 on the substrate 11, and then the first base layer 13A is formed. By forming the second underlayer 13B in a region corresponding to the first region D1, the concentration distribution of the catalyst material for the electroless plating process is higher in the first region D1 than in the second region D2. Therefore, when the electroless plating process is performed on the substrate 11 on which the first base layer 13A and the second base layer 13B are formed, the film formation rate in the first region D1 becomes higher than that in the second region D2.

  As described above, according to the method for forming the metal thin film 10 of the present embodiment, the first underlayer 13A is formed over the first region D1 and the second region D2 on the substrate 11, and then the first underlayer. Since the second underlayer 13B is formed in the region corresponding to the first region D1 on 13A, the concentration distribution of the electroless plating catalyst material is higher in the first region D1 than in the second region D2. . Therefore, by performing an electroless plating process on the substrate 11 on which the first base layer 13A and the second base layer 13B are formed, the film formation rate in the first region D1 is higher than that in the second region D2, A taper 14-1 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 the metal layer is formed by a vacuum deposition method or the like, which increases the number of steps. End up.

  FIG. 12A shows a photograph of a cross section of a metal thin film (dotted line portion in the drawing) in which a chromium film is deposited by vacuum deposition and then tapered by wet etching. As described above, when the taper is formed by wet etching, isotropic etching is performed, so that the taper portion does not become linear, and in particular, the upper end of the metal thin film has an angle close to vertical. In this case, if another layer is laminated on the metal thin film, the uniformity of the thickness of the other layer is deteriorated, so that disconnection or the like is likely to occur. Note that FIG. 12B shows a schematic diagram of a cross-sectional shape of a metal thin film when taper is formed by dry etching. As described above, taper formation using dry etching utilizes receding of a mask such as a resist, so that the taper shape is linear, but the number of processes increases as described above.

  Therefore, in order to reduce the number of processes, it is considered that a metal thin film is formed by electroless plating treatment. However, since the plating film is usually deposited using a catalyst as a nucleus, it is difficult to obtain a desired tapered shape. It is.

  On the other hand, in the present embodiment, the taper can be formed by the full additive method using the electroless plating process by adjusting the concentration distribution of the base layer containing the catalyst material for the electroless plating process. For this reason, the patterning process after film-forming becomes unnecessary. Therefore, the taper can be easily formed by a simple process.

  Further, by appropriately setting the ratio of the width x of the first region D1 to the width W of the entire metal thin film 10 and the film thicknesses of the first base layer 13A and the second base layer 13B, etc., according to the specifications of the wiring and electrodes. A desired taper shape can be easily formed.

  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 layer to be an electrode by a vapor deposition 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. Thereby, generation | occurrence | production of a leakage current etc. can be suppressed by forming desired taper shape in each electrode.

  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.

[Second Embodiment]
FIG. 9 shows a cross-sectional configuration of the metal thin film 21 according to the second embodiment of the present invention. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  The metal thin film 21 is formed using an electroless plating method described later, and is provided on the substrate 11 via the adhesion layer 12, for example. The metal thin film 21 includes a first base layer 23A, a second base layer 23B, and a plating layer 24, and a taper (inclined surface) 24-1 is formed in the end region. The metal thin film 21 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 21.

  The first base layer 23A is provided in the first region D1 (the central region of the metal thin film 21) on the substrate 11 with a thickness of, for example, several nm to several tens of nm. The second underlayer 23B is formed in the second region D2 on the substrate 11 with a thickness of, for example, several nm to several tens of nm. As the constituent materials of the first base layer 23A and the second base layer 23B, the same materials as those of the first base layer 13A and the second base layer 13B of the first embodiment can be used.

  In the present embodiment, the concentration of the catalyst material for the electroless plating process is higher in the first base layer 23A than in the second base layer 23B. Accordingly, the concentration distribution of the catalyst material for the electroless plating process is higher in the first region D1 on the substrate 11 than in the second region D2.

  The plating layer 24 is formed so as to cover the first base layer 23A and the second base layer 23B over the entire surface of the first region D1 and the second region D2. The plating layer 24 has a thickness of, for example, several tens nm to several hundreds nm, and is deposited by an electroless plating process described later. As a material constituting the plating layer 24, the same material as the plating layer 14 of the first embodiment described above can be used.

  In addition, the metal thin film 21 having such a configuration can be formed as follows. First, as illustrated in FIG. 10, the first base layer 23 </ b> A and the first region D <b> 2 are formed in the first region D <b> 1 on the substrate 11 on which the adhesion layer 12 is formed by using, for example, the μ contact printing method as described above. Second base layers 23B are formed respectively. Thereafter, the substrate 11 on which the first underlayer 23A and the second underlayer 23B are formed is subjected to electroless plating as described above to form a plating layer 24, thereby forming the metal shown in FIG. A thin film 21 can be formed.

  Thus, in the present embodiment, the concentration of the catalyst material for the electroless plating process is higher on the substrate 11 than on the second underlayer 23B on the first underlayer 23A. In the first region D1, the concentration distribution of the catalyst material for the electroless plating process is higher than in the second region D2, and the end region of the metal thin film 21 can be tapered.

(Example)
Next, examples of the present invention will be described.

  As an example, the metal thin film 10 was formed by the method for forming the metal thin film 10 of the first embodiment. At this time, an amino silane coupling agent KBM-603 (trade name) manufactured by Shin-Etsu Chemical Co., Ltd. as an adhesion layer 12 on a substrate 11 made of glass, Toray Dow Corning Silicone Co., Ltd. is used as a stamp material. SYLGARD 184 (trade name) manufactured by the company was used. As a catalyst imparting agent to this stamp, a palladium catalyst imparting agent (OPC50 inducer: trade name) manufactured by Okuno Seiyaku Co., Ltd. was used, and the first foundation layer 13A and the second foundation layer 13B were respectively formed on the adhesion layer 12. Printed. 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. At 60 ° C., the immersion time was 1 minute, the film formation rate was 200 nm / min, and the desired width (thickness) W was 50 μm.

  FIG. 11A shows a cross-sectional shape of the end portion of the metal thin film 10 formed as described above. As a comparative example of the above example, FIG. 11B shows a cross-sectional shape of an end portion of a metal thin film formed by performing an electroless plating process without imparting a concentration distribution of the catalyst material to the underlayer. In the comparative example, after forming the 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. 11B, when an electroless plating process is performed without imparting a concentration distribution to the underlayer and a metal thin film is formed so as to have a desired width W, the end portion is steep. As a result, a large step occurs. 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. 11A, when an electroless plating process is performed with a concentration distribution applied to the underlayer and a metal thin film is formed so as to have a desired width W, the end portion becomes loose. Thus, the problem as in the comparative example does not occur. Therefore, after forming the base layer so that the concentration distribution of the catalyst material is higher in the first region D1 on the substrate 11 than in the second region D2, by performing an electroless plating process using this base layer as a catalyst, It was shown that a desired taper shape can be easily formed in the end region of the metal thin film 10.

  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-described embodiment, the second region D2 is formed on the substrate 11 with the same width x at both ends of the first region D1, and the same tapered shape is formed in the second region D2. However, the present invention is not limited to this, and the number, position, width, shape, inclination angle, etc. of the taper are appropriately set according to the required pattern. For example, the second base layer 13B may be formed only in the region on the first base layer 13A side, and the taper 14-1 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 in the both ends of the metal thin film 10, respectively.

  In the above-described embodiment and the like, the configuration in which the catalyst material concentration distribution is divided into two regions of the first region D1 and the second region D2 is described as an example. However, the present invention is not limited to this. The concentration distribution of the catalyst material may be different in three or more regions. Even in such a case, a desired taper shape can be formed if, for example, the concentration is gradually decreased from the central region to the end region of the metal thin film.

  In the above-described embodiment and the like, as an example of a method for making the concentration distribution of the catalyst material higher in the first region D1 than in the second region D2, each catalyst layer having the same concentration is applied to the first region D1 twice. Although the case where the transfer is performed once in the second region D2 has been described, the present invention is not limited to this. If the number of times of transfer in the first region D1 is larger than that in the second region D2, the same effect as in the present invention. Can be obtained.

  In the above-described embodiment and the like, as an example of a method for increasing the concentration distribution of the catalyst material in the first region D1 than in the second region D2, catalyst layers having different concentrations in the first region D1 and the second region D2 are used. Although the case where the transfer is performed once has been described, the present invention is not limited to this. The number of transfers is not particularly limited as long as the density distribution in the first region D1 is higher than that in the second region D2. In addition, the first base layer 23A and the second base layer 23B are separately formed in the first region D1 and the second region D2, respectively. However, the present invention is not limited to this, and the first region D1 and the second region Underlayers having different concentrations from D2 may be collectively formed.

  In addition to the thin film transistor 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 the 1st 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. It is sectional drawing showing the metal thin film which concerns on the 1st Embodiment of this invention. It is sectional drawing for demonstrating the formation method of the metal thin film shown in FIG. 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, 21 ... Metal thin film, 10a ... Gate electrode, 10b ... Source electrode, 10c ... Drain electrode, 11, 15 ... Substrate, 12 ... Adhesion layer, 13A, 23A ... 1st base layer, 13B, 23B ... Second base layer, 14, 24 ... plating layer, 16 ... buffer layer, 17 gate insulating film, 18 ... α-Si (n +) layer, 19 ... α-Si (i) layer, 20 ... passivation film.

Claims (6)

Forming a base layer containing a catalyst material for electroless plating in a first region on the substrate and a second region in the vicinity of the first region;
Forming a plating layer by applying an electroless plating treatment to the substrate on which the foundation layer has been formed, using the foundation layer as a catalyst,
The method for forming a metal thin film, wherein the underlayer is formed so that the concentration distribution of the catalyst material is higher in the first region than in the second region. The step of forming the underlayer includes
After forming a first underlayer on the entire surface of the first region and the second region on the substrate,
2. The method for forming a metal thin film according to claim 1, wherein a second underlayer is formed in a region facing the second region on the first underlayer. The method for forming a metal thin film according to claim 2, wherein the first underlayer and the second underlayer have the same concentration of the catalyst material. The step of forming the underlayer includes
After forming a first underlayer in the first region on the substrate,
The method for forming a metal thin film according to claim 2, wherein a second underlayer having a lower concentration of the catalyst material than the first underlayer is formed in the second region on the substrate. 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 base layer containing a catalyst material for electroless plating in a first region on the substrate and a second region in the vicinity of the first region;
Forming a plating layer by applying an electroless plating treatment to the substrate on which the foundation layer has been formed, using the foundation layer as a catalyst,
The method of manufacturing a thin film transistor, wherein the underlayer is formed so that a concentration distribution of the catalyst material is higher in the first region than in the second region. A first underlayer provided in a region on the substrate and containing a catalyst material for electroless plating;
A second underlayer provided in a central region on the first underlayer and containing a catalyst material of an electroless plating material;
A metal thin film comprising: a plating layer formed so as to cover the first and second underlayers and having an inclined surface in an end region.

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