JP2008216947A - Polymer chain/thin film growing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate feed-rate control of reactive molecular gas in polymer chain/thin film growth, to improve growth controllability by excluding byproducts from a growth region, to increase utilization efficiency of the reactive molecule, and to attain the high speed of molecular switching speed. <P>SOLUTION: Effective means are: CG-MLD/OCVD; MLD/OCVD using a solution; FC-MLD/OCVD using a flow passage circuit; and MLD/OCVD using a seed core. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

Detailed Description of the Invention

    The present invention relates to a polymer chain / thin film growth method including a step of supplying a plurality of reactive molecules to a substrate, and a polymer chain / thin film growth method including a step of sequentially supplying a plurality of reactive molecules to a substrate and controlling the molecular arrangement. (MLD: Molecular Layer Deposition), in particular, a polymer chain / thin film growth method in which reactive molecules are transported by a carrier gas and supplied to a substrate, and a polymer chain / thin film that is dissolved in a solvent and transported to the substrate. Polymer chain supplying a reactive molecule to a substrate by a growth method, a flow path circuit arranged on the substrate, and a reactive molecule and / or a mixed gas of a reactive molecule and a carrier gas and / or a solution of the reactive molecule flowing. / Thin film growth method, and polymer chain / thin film growth in which a molecule having a group that reacts with at least one kind of reactive molecule is arranged on at least a part of the substrate Regarding the law.

  FIG. 1 shows the principle of MLD (Non-patent Documents 1 and 2, Patent Document 3). In the following, the case where a plate-like substrate is used as the growth substrate will be described. In this example, four types of molecules (molecules A1a, B1b, C1c, D1d) are used. Each molecule has two or more (in this example, two) reactive groups, the same type of molecule does not react, and different types of molecules are set to react and bond. By supplying multiple types of reactive molecules to the surface of the substrate in sequence, polymer chains with molecular arrangements grow. When a molecule having three or more reactive groups is introduced, the molecular wire can be branched. MLD is also possible by using ionic molecules. In this case, an electron donating molecule and an electron accepting molecule are alternately supplied to perform molecular arrangement controlled growth. Further, vapor deposition polymerization (organic CVD) is known in which a polymer thin film is grown by simultaneously introducing a plurality of gasified reactive molecules on a substrate placed in a vacuum. Conventionally, as a method for embodying MLD / organic CVD, a substrate is placed in a vacuum chamber, and gasified reactive molecules are supplied from the cell to the surface (Non-Patent Documents 1 and 2). . When the reactive molecular gas is evaporated from the cell, it is necessary to precisely control the gas supply rate by feedback from various monitoring in order to improve the controllability of polymer growth. Usually, a by-product is generated near the substrate with the reaction. This sometimes hindered the controllability of polymer growth. As another technique, a reactive molecule is dissolved in a solvent and supplied to the substrate surface as a solution (Patent Document 4). In this case, there were problems in manufacturing such as utilization efficiency of reactive molecules and molecular switching speed.

  T.A. Yoshimura, S .; Tatsuura, and W.H. Sotoyama, "Polymer films formed with monolayer growth steps by molecular layer deposition," Appl. Phys. Lett. , Vol. 59, no. 4, pp. 482-484, 1991.   T.A. Yoshimura, S .; Tatsuura, W. et al. Sotoyama, A .; Matsuura, and T.M. Hayano, “Quantum wire and dot formation by chemical vapor deposition and molecular layer deposition of one-dimensional conjugated polymer,” Appl. Phys. Lett. , Vol. 60, no. 3, pp. 268-270, 1992.   T.A. Yoshimura, E .; Yano, S .; Tatsuura, and W.H. Sotoyama, “Organic functional optical thin film, fabrication and use thereof,” US Patent 5,444,811, 1995.   T.A. Yoshimura, “Liquid Phase Deposition,” Japan Disclosure: Tokukaihei 3-60487, 1991. (In Japan)

Problems to be solved by the invention

  The object of the present invention is to facilitate the control of the reactive molecular gas supply rate and improve the controllability of polymer chain / thin film growth in MLD / organic CVD, and to eliminate the by-products accompanying the reaction from the growth region. It is to improve the controllability of chain / thin film growth, to improve the utilization efficiency of reactive molecules, and to improve the molecular switching speed.

Means for solving the problem

  The polymer chain / thin film growth according to the first aspect of the present invention is characterized in that reactive molecules are carried by a carrier gas and supplied to a substrate. Thereby, the reactive gas can be efficiently guided to the substrate with good controllability. Also, by-products can be excluded from the polymer chain / thin film growth region by the carrier gas.

  The polymer chain / thin film growth according to the second aspect of the present invention is characterized in that the reactive molecules are dissolved in a solvent and are supplied to the substrate. As a result, reactive molecules can be efficiently introduced to the substrate, the utilization efficiency of the reactive molecules can be improved, and the reaction rate can be controlled by adding a catalyst to the solution.

  In the polymer chain / thin film growth according to the third aspect of the present invention, a flow path circuit is arranged on a substrate, and a reactive molecule and / or a mixed gas of a reactive molecule and a carrier gas is provided in the flow path circuit, and / or The reactive molecule is supplied to the substrate by flowing a solution of the reactive molecule. As a result, the required amount of molecular gas and solution can be significantly reduced, so that the utilization efficiency of reactive molecules and the molecular switching speed can be improved.

  The polymer chain / thin film growth according to the fourth aspect of the present invention is characterized in that a molecule having a substituent that reacts with at least one kind of reactive molecule is disposed on at least a part of the substrate. As a result, the polymer chain / thin film can be selectively grown on the necessary portion of the substrate.

  The present embodiment will be described below with reference to the drawings. In each figure, the same reference numerals indicate the same elements, and duplicate descriptions are omitted. The following description explains an embodiment to which the present invention is applicable, and the scope of the present invention is not limited to this description. For clarity of explanation, the following description has been omitted and simplified as appropriate. Further, those skilled in the art will be able to easily change, add, and convert each element of the following embodiments within the scope of the present invention.

[First Embodiment]
FIG. 2 is a schematic diagram of carrier gas type MLD (CG-MLD) and carrier gas type organic CVD (CG-OCVD) according to the present invention. An example in which a polymer chain is constructed by CG-MLD using four types of reactive molecules A1a, B1b, C1c, and D1d will be described. Reactive molecules are loaded into the cell and each is heated (or cooled) to the appropriate temperature and partially gasified. An inert gas such as Ar, N ₂ or He is introduced into these cells as a carrier gas. As a result, the reactive molecular gas is supplied to the surface of the substrate 3 in the chamber 6 by the carrier gas. The reactive molecular gas to be supplied is switched by valves A2a, B2b, C2c, and D2d. Further, the supplied gas becomes a gas flow 5 by a pump and is removed out of the chamber 6. Although not shown, a purge with an inert gas or a surface modification process with an active gas can be inserted in the middle of switching the reaction gas.

FIG. 3 shows examples of reaction molecules used and reactions. Poly-azomethine (AM), which is a conjugated polymer chain, grows by the reaction of p-phenylenediamine (PPDA) and terephthalaldehyde (TPA). A by-product is H ₂ O. Further, a polymer chain grows by the reaction of oxalic dihydrazide (OD) and oxalic acid (OA), and becomes a conjugated polymer poly-oxadiazole (OXD) by heat treatment at 200-300 ° C. FIG. 4 shows an example of molecular chain growth by MLD. A self-assembled monolayer (SAM) of aminoalkanethiol (11-Amino-1-undecanethiol) is formed on the gold film. The surface is covered with —NH ₂ groups. When TPA is supplied thereon, the —CHO group is bonded to the —NH ₂ group of the SAM, and the surface is covered with the —CHO group. When PPDA is supplied thereon, the —NH ₂ group is bonded to the —CHO group of SAM, and the surface is covered with the —NH ₂ group. Further, when a molecule having two —CHO groups is supplied on PPDA, the —CHO group is bonded to the —NH ₂ group, and the surface is covered with the —CHO group. Supplying molecular group -NH ₂ with two thereon -NH ₂ group is bound to the surface and -CHO are covered with -NH ₂ group. By repeating this, a molecularly arranged polymer chain is formed. Here, PPDA and TPA are heated to about 50 to 150 ° C., whereby gasification is promoted, and molecular introduction is efficiently performed. In CG-MLD, H ₂ O as a by-product is removed from the growth surface by the carrier gas. For this reason, the reactive molecule comes to react only with the reactive group at the end of the polymer. As a result, a desired polymer chain structure can be grown (when H ₂ O is present in the growth region, reactive molecules are adsorbed there, which becomes a nucleus and unnecessary growth occurs). The orientation of poly-AM grown by CG-MLD was examined by FTIR-RAS. Since the intensity ratio of the in-plane vibration of the benzene ring to the out-of-plane vibration is larger than that without 11-Amino-1-undecanethiol, it is understood that the polymer chain growth as shown in FIG. It was.

In organic CVD in which TPA and PPDA are supplied simultaneously, a by-product H ₂ O exists on the surface. This becomes an adsorption site and becomes a nucleus, and poly-AM grows randomly. For this reason, film quality deteriorates. On the other hand, in CG-OCVD, H ₂ O is removed from the growth surface by the carrier gas. For this reason, the reactive molecule adsorption site is only the reactive group at the end of the polymer chain. As a result, high-quality poly-AM can be formed. This can also be confirmed from the saturation phenomenon of film growth that is specifically observed in CG-OCVD. That is, in CG-CVD, when poly-AM is formed on SiO ₂ under conditions of a molecular cell temperature of 50 ° C. and a flow rate of 4 NL / min, a saturation tendency is observed in the film growth after a film formation time of 20 minutes or more, and 80 nm. The film thickness reached a certain level. This is presumably because the density of the reactive group at the end of the polymer chain, which is the reactive site, decreases as the film grows, and the growth rate decreases. This was confirmed from the fact that the hydrophobicity of the membrane surface became stronger with the deposition time. In normal organic CVD, the saturation phenomenon as described above is not observed, and the film thickness of poly-AM increases with the growth time.

[Second Embodiment]
In CG-MLD and CG-OCVD shown in FIG. 2, growth can be performed using a cell into which a solution of reactive molecules A, B, C, and D is injected instead of the gasification cell. In the case of CG-MLD, one of these solutions is introduced into a reactor in which a substrate is arranged. As a result, reactive molecules are supplied and bonded to the substrate surface. After draining the solution, the valve is switched to introduce another type of solution into the reactor. As a result, molecules are bonded and molecular chains grow. Similarly, MLD is performed by switching reactive molecules. When the solution is switched, it is possible to insert a purge with a cleaning solvent or a surface modification process with an active liquid in the middle. It is also possible to introduce a plurality of types of solutions into the reactor at the same time. This corresponds to CG-OCVD.

[Third Embodiment]
FIG. 5 is a schematic diagram of a channel circuit type MLD (FC-MLD) and a channel circuit type OCVD (FC-OCVD) according to the present invention. A solution is prepared by dissolving four types of reactive molecules A1a, B1b, C1c, and D1d in a solvent. Load this into the cell. In the case of FC-MLD, these solutions are introduced into a reactor composed of the flow path circuit 11 one by one using, for example, a twin pump or electrophoresis. As a result, reactive molecules are supplied to the surface of the substrate 8 constituting a part of the reactor. Switching of reactive molecules is performed by valves A7a, B7b, C7c, and D7d. Further, the supplied solution becomes a liquid flow 10 and is removed out of the flow path circuit 11. When the solution is switched, it is possible to insert a purge with a cleaning solvent or a surface modification process with an active liquid in the middle. In the case of FC-OCVD, multiple types of solutions are introduced simultaneously. The flow path is formed by, for example, forming a flow path pattern substrate using a photocurable resin such as SU8, forming a flow path pattern by molding or imprinting, forming a flow path pattern by etching, or the like. This can be achieved by pressure bonding or bonding to the substrate surface. The depth of the flow path is typically in the range of about 1 μm-1 mm.

  Further, instead of a solution, a reactive molecular gas or a mixed gas of a reactive molecular gas and a carrier gas can be introduced into the flow path circuit. In this case, it is necessary to adjust the temperature of the flow path circuit so that the gas does not solidify and precipitate.

  FIG. 6 shows that in FC-MLD and FC-OCVD, channel-type flow paths 11a, 11b, 11c, and 11d are assigned to each reactive molecule supply, and these are merged into the film-forming flow path 11e to obtain a necessary amount of solution. This is a further reduced example. A cleaning solvent channel (or purge gas channel) 9 'is provided for each channel.

[Fourth Embodiment]
FIG. 7 shows an example of three-dimensional selective orientation growth by the polymer chain / thin film growth method of the present invention. A SAM 24 is formed on the gold surface and / or wall surface to produce a seed core 22. A place where SAM is not desired to be formed on gold is covered with, for example, SiO ₂ 23. Polymer wires 25 grow upward from the seed core surface and laterally from the wall surface. A desired polymer wire network 26 is constructed by distributing the seed cores in a pre-designed pattern.

  FIG. 8 shows an example of an optical modulator / optical switch that can be constructed using the polymer chain / thin film growth method according to the present invention. In a Waveguide Prism Reflector (WPD) type optical switch, a prism type electrode 30 is formed on an electro-optic (EO) slab waveguide 31, and the waveguide light is deflected by induction of the waveguide prism by voltage application. In the total reflection (TIR) type optical switch, the EO waveguide 32 is crossed and the optical path is switched by the electrode 31 thereon. In a high-index-contrast (HIC) waveguide ring resonator, an electrode is provided in the ring waveguide portion of the EO waveguide, and switching is performed by inducing a change in the resonance state. In a photonic crystal, an electrode is placed on an EO material to generate a switching phenomenon. In the EO waveguide and EO material, preferably, the conjugated polymer 34 is selectively grown by molecular arrangement by MLD.

  This is the concept of MLD.   It is a schematic diagram of carrier gas type MLD (CG-MLD) and carrier gas type organic CVD (CG-OCVD) according to the first embodiment of the present invention.   This is an example of the molecules and reactions used.   It is a schematic diagram of polymer wire growth from SAM.   It is a schematic diagram of channel circuit type MLD (FC-MLD) and channel circuit type OCVD (FC-OCVD) according to a third embodiment of the present invention.   It is a schematic diagram of FC-MLD and FC-OCVD according to a third embodiment of the present invention.   It is a schematic diagram of polymer wire growth from a seed core according to a fourth embodiment of the present invention.   It is a schematic diagram of the optical modulator and optical switch that can be constructed using the MLD according to the first to fourth embodiments of the present invention.

Explanation of symbols

Molecule A 1a, molecule B 1b, molecule C 1c, molecule D 1d, valve A 2a, valve B 2b, valve C 2c, valve D 2d, substrate 3, carrier gas 4, gas flow 5, chamber 6, valve A 7a, Valve B 7b, Valve C 7c, Valve D 7d, Substrate 8, Cleaning solvent 9, Cleaning solvent micro flow path 9 ', Liquid flow 10, Flow path circuit 11, Molecular A flow path 11a, Molecular B flow path 11b, flow path for molecule C 11c, flow path for molecule D 11d, flow path for film formation 11e, substrate for flow path circuit 12, seed core 22, SiO ₂ 23, SAM 24, polymer wire 25, polymer wire network 26, electrode 30 , EO slab waveguide 31, EO waveguide 32, EO material 33, conjugate polymer wire 34, guided light 35

Claims (6)

  A polymer chain / thin film growth method comprising a step of supplying a plurality of reactive molecules to a substrate, wherein the reactive molecules are carried by a carrier gas and supplied to the substrate.   In a polymer chain / thin film growth method including a step of sequentially supplying a plurality of reactive molecules to a substrate and controlling the molecular arrangement, the reactive molecules are carried by a carrier gas and supplied to the substrate. Thin film growth method.   A polymer chain / thin film growth method comprising a step of supplying a plurality of reactive molecules to a substrate, wherein the reactive molecules are dissolved in a solvent, and are supplied to the substrate. .   In a polymer chain / thin film growth method including a step of sequentially supplying a plurality of reactive molecules to a substrate and controlling the molecular arrangement, the reactive molecules are dissolved in a solvent and are supplied to the substrate. Polymer chain / thin film growth method.   5. The polymer chain / thin film growth method according to claim 1-4, wherein a flow path circuit is disposed on a substrate, and in the flow path circuit, a reactive molecule and / or a mixed gas of a reactive molecule and a carrier gas, and / or Alternatively, a polymer chain / thin film growth method characterized in that the reactive molecule is supplied to the substrate by flowing a solution of the reactive molecule.   6. The polymer chain / thin film growth method according to claim 1, wherein a molecule having a group that reacts with at least one kind of reactive molecule is disposed on at least a part of the substrate. .

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