JP2018169240A - Sensor manufacturing system, method for manufacturing sensor, and sensor - Google Patents

Abstract

To provide a sensor in which the variation in the measured value is made smaller.SOLUTION: A sensor manufacturing system 100 includes: a film forming device 110 for forming, on a substrate, a graphite layer and a nano structure layer made of a plurality of carbon nano walls; and a laser emission device 120 for making the nano structure layer ablated while leaving the graphite layer by emitting a laser with a pulse width of less than 10seconds in a specific region of the nano structure layer. The thus obtained sensor has reduced noise and an improved S/N ratio.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a sensor manufacturing system, a sensor manufacturing method, and a sensor for manufacturing a sensor using carbon nanowalls.

  A carbon nanowall (Carbon Nano Wall: CNW) is a nanostructure having a fine shape of nanometer size (several nm to several tens of nm) (for example, Patent Document 1). Carbon nanowalls have characteristics that dramatically improve the characteristics of conventional materials, or characteristics that are not found in conventional materials. Therefore, carbon nanowalls are expected as next-generation functional materials such as electromagnetic wave absorbing materials, battery electrode materials, catalyst materials, semiconductor materials, electron-emitting device materials, optical materials, strength reinforcing materials, and sensors.

  For example, Non-Patent Document 1 discloses a biosensor in which a number of carbon nanowalls are formed on an electrode.

Japanese Patent No. 5987546

Shun Mao et al. SCIENTIFIC REPORTS 3: 1696 DOI: 10.1038 / srep01696

  In the conventional sensor described in Non-Patent Document 1, since a large number of carbon nanowalls are in contact with the electrodes, a plurality of paths through which current flows are formed. Therefore, the conventional sensor has a problem that the fluctuation range of the measured value is large.

  An object of the present disclosure is to provide a sensor manufacturing system, a sensor manufacturing method, and a sensor capable of reducing a fluctuation range of a measurement value.

In order to solve the above problems, a sensor manufacturing system according to one embodiment of the present disclosure includes a film formation apparatus that forms a graphite layer and a nanostructure layer including a plurality of carbon nanowalls on a substrate. And a laser irradiation apparatus for irradiating a predetermined region of the nanostructure layer with a laser having a pulse width of less than 10 ⁻¹² seconds to ablate the nanostructure layer while leaving the graphite layer.

  Further, the film forming apparatus may dope a metal into one or both of the graphite layer and the carbon nanowall.

  The laser irradiation apparatus may irradiate the laser on two regions of the nanostructure layer that are separated from each other.

  Further, the laser irradiation apparatus may include a beam homogenizer.

In order to solve the above problem, a sensor manufacturing method according to an aspect of the present disclosure includes a step of forming a graphite layer on a substrate, and a nanostructure including a plurality of carbon nanowalls on the graphite layer. Forming a structural layer; and irradiating a predetermined region of the nanostructure layer with a laser having a pulse width of less than 10 ⁻¹² seconds to ablate the nanostructure layer while leaving the graphite layer remaining And including.

  In order to solve the above problems, a sensor according to one embodiment of the present disclosure includes a substrate, a graphite layer provided on the substrate, and a plurality of carbons formed in a predetermined region of the graphite layer. A nanostructure layer including a nanowall.

  It is possible to reduce the amplitude of the measured value.

It is a figure explaining a sensor manufacturing system. It is a figure explaining the specific structure of the film-forming apparatus. It is a figure explaining carbon nanowall. It is a flowchart explaining the flow of a process of a sensor manufacturing method. It is a figure explaining each process of a sensor manufacturing method. It is a figure explaining the sensor manufactured using the sensor structure, and the conventional sensor. FIG. 7A is a first diagram illustrating the height from the substrate in the embodiment. FIG. 7B is a second diagram for explaining the height from the substrate in the embodiment. FIG.7 (c) is an image which shows the result of having observed the Example with the scanning electron microscope (SEM). FIG. 7D is a partially enlarged image of the laser irradiation region in FIG. It is a figure explaining the sensor of a modification.

  Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiment are merely examples for facilitating understanding, and do not limit the present disclosure unless otherwise specified. In the present specification and drawings, elements having substantially the same functions and configurations are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present disclosure are not illustrated. To do.

(Sensor manufacturing system 100)
FIG. 1 is a diagram for explaining a sensor manufacturing system 100. As shown in FIG. 1, the sensor manufacturing system 100 includes a film forming apparatus 110 and a laser irradiation apparatus 120. The film forming apparatus 110 forms a graphite layer and a nanostructure layer including a plurality of carbon nanowalls on a substrate.

  FIG. 2 is a diagram for explaining a specific configuration of the film forming apparatus 110. As shown in FIG. 2, the film forming apparatus 110 is a so-called plasma CVD (Chemical Vapor Deposition) apparatus, and includes a chamber 210, a substrate holder 220, a target holding unit 230, and a plasma gun 240. .

A gas supply port 212 is formed in the chamber 210. A reactive gas is supplied into the chamber 210 through the gas supply port 212. The reaction gas is a gas that can form carbon nanowalls such as methane (CH ₄ ). Further, a vacuum pump (not shown) is connected to the chamber 210, and the inside is maintained at a predetermined pressure by the vacuum pump.

  The substrate holder 220 is disposed in the chamber 210 and holds the substrate S. The substrate S includes an element that easily forms a carbide such as silicon (Si).

  The target holding unit 230 is disposed in the chamber 210 and holds the sputtering target T. The sputtering target T includes lithium (Li), beryllium (Be), sodium (Na), magnesium (Mg), aluminum (Al), potassium (K), calcium (Ca), scandium (Sc), titanium (Ti), Vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), rubidium (Rb), Strontium (Sr), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), Indium (In), tin (Sn), cesium (Cs), barium (Ba), lanthanum (La), cerium (Ce) Praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), Ytterbium (Yb), lutetium (Lu), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), It is composed of one metal selected from the group consisting of mercury (Hg), thallium (Tl), lead (Pb), and bismuth (Bi), or a plurality of alloys. Further, the target holding unit 230 allows a pulse current (DC) to flow through the sputtering target T at a predetermined frequency.

  The plasma gun 240 emits a plasma flow PF into the chamber 210. Since the plasma gun 240 can use various existing technologies (for example, Japanese Patent Application Laid-Open No. 2008-056546), detailed description thereof is omitted here. When the plasma gun 240 releases the plasma flow PF, the plasma constituting the plasma flow PF decomposes the reaction gas and collides with the sputtering target T. As a result, a graphite layer is formed on the substrate S, and a plurality of carbon nanowalls are formed on the graphite layer. In addition, atoms constituting the sputtering target T are released from the sputtering target T (sputtering), and are doped into one or both of the graphite layer and the plurality of carbon nanowalls.

  FIG. 3 is a diagram for explaining a carbon nanowall (CNW). In FIGS. 3B and 3D of the present embodiment, the X axis, the Y axis, and the Z axis that intersect perpendicularly are defined as illustrated. The carbon nanowall is composed of a graphene sheet as shown in FIG. 3A (the carbon atom (C) is indicated by a white circle in FIG. 3A), and the surface of the substrate S as shown in FIG. It stands up from the top (growth vertically). When the carbon nanowall is formed on the substrate S, as shown in FIGS. 3C and 3D, first, a graphite layer (hereinafter referred to as “graphite layer”) is formed on the surface of the substrate S. Is formed). The graphite layer is formed on the surface of the substrate S along the in-plane direction of the surface of the substrate S. For example, the graphite layer is formed on the surface of the substrate S in parallel with the in-plane direction of the surface of the substrate S.

  A plurality of carbon nanowalls extend (extend) through the graphite layer in a direction perpendicular to the surface of the substrate S (the Y-axis direction in FIGS. 3B and 3D). It is formed. Here, the thickness of the carbon nanowalls in the direction parallel to the substrate S (X-axis direction in FIG. 3B) is 1 nm or more and 100 nm or less, and the X-axis in FIG. 3B between the carbon nanowalls. The distance in the direction is also 1 nm or more and 10 μm or less.

  Since carbon nanowalls have a self-organizing function, a nanometer-sized void is formed between a plurality of carbon nanowalls simply by generating plasma in the atmosphere of the reaction gas in the film forming apparatus 110. However, the carbon nanowall grows so as to extend in the direction perpendicular to the surface of the substrate S (the Y-axis direction in FIG. 3). Here, the nanometer size refers to 1 nm or more and 10 μm or less. Hereinafter, a layer including a plurality of carbon nanowalls is referred to as a nanostructure layer.

Referring back to FIG. 1, the laser irradiation device 120 irradiates a predetermined region of the nanostructure layer with a laser having a pulse width of less than 10 ⁻¹² seconds. Laser irradiation device 120, for example, pulse width laser and femtosecond ^{(10 -15} seconds), the pulse width is irradiated with a laser attosecond ^{(10 -18} seconds).

The energy density of the laser irradiated by the laser irradiation device 120 is an energy density for ablating the nanostructure layer while leaving the graphite layer on the substrate S remaining (without breaking). The energy density is determined based on the thickness of the nanostructure layer. The energy density is, for example, 5 × 10 ¹³ W / cm ² or more. Note that there is no limitation on the wavelength of the laser irradiated by the laser irradiation device 120.

  The laser irradiation device 120 includes a beam homogenizer. A beam homogenizer is an optical system that homogenizes the energy distribution of a laser. The beam homogenizer includes, for example, a lens array, an aspheric lens, and a diffractive optical element (DOE). Since the beam homogenizer configured to include the lens array can use various existing technologies (for example, Japanese Patent No. 5446618), detailed description thereof is omitted here. In addition, a beam homogenizer configured to include an aspheric lens can use various existing technologies (for example, Japanese Patent Laid-Open No. 2013-29748), and thus detailed description thereof is omitted here. A beam homogenizer configured to include a diffractive optical element can use various existing techniques (for example, Japanese Patent Application Laid-Open No. 2008-69066), and thus detailed description thereof is omitted here. When the laser irradiation device 120 includes a beam homogenizer, the smoothness of the laser irradiation region can be improved.

(Sensor manufacturing method)
Subsequently, a sensor manufacturing method using the sensor manufacturing system 100 will be described. FIG. 4 is a flowchart for explaining the flow of processing of the sensor manufacturing method. FIG. 5 is a diagram for explaining each step of the sensor manufacturing method. In FIG. 5 of the present embodiment, the X axis, the Y axis, and the Z axis that intersect perpendicularly are defined as illustrated.

  As shown in FIG. 4, the sensor manufacturing method of the present embodiment includes a first film forming step S110, a second film forming step S120, and a laser irradiation step S130. Hereinafter, the details of the first film forming step S110, the second film forming step S120, and the laser irradiation step S130 will be described.

(First film formation step S110)
The first film forming step S110 is a step of doping the graphite layer with a metal while forming the graphite layer on the substrate S using the film forming apparatus 110.

  First, the substrate S is held by the substrate holder 220, and the reaction gas is supplied into the chamber 210 through the gas supply port 212. Then, the plasma gun 240 is driven, and at the same time, supply of a pulse current to the sputtering target T by the target holding unit 230 is started. That is, simultaneously with the start of film formation of the graphite layer on the substrate S, the graphite layer is doped with metal.

  Then, after the first predetermined time has elapsed from the start of driving of the plasma gun 240, the supply of the pulse current to the sputtering target T is stopped. The driving of the plasma gun 240 is continued. Here, the first predetermined time is a time for forming the graphite layer on the substrate S and a time until the carbon nanowall (nanostructure layer) is formed.

  Then, as shown in FIG. 5A, a graphite layer (hereinafter referred to as “underlayer”) 310 doped with metal is formed on the substrate S. The foundation layer 310 is a layer formed along the in-plane direction of the surface of the substrate S.

(Second film formation step S120)
The second film formation step S120 is a step of forming a nanostructure layer on the base layer 310 using the film formation apparatus 110.

  Specifically, after the completion of the first film forming step S110, the driving of the plasma gun 240 is maintained for a second predetermined time. Here, the second predetermined time is a time during which a carbon nanowall having a thickness (the height in the Y-axis direction in FIG. 5) that can be used as a sensor is formed.

  Then, as shown in FIG. 5B, the sensor material 330 in which the nanostructure layer 320 is formed on the underlayer 310 is manufactured. The nanostructure layer 320 is a layer including a plurality of carbon nanowalls 322. The carbon nanowall 322 extends from the base layer 310 in a direction (Y-axis direction in FIG. 5) perpendicular to the surface (in-plane direction) of the substrate S. In the nanostructure layer 320, the carbon nanowall 322 extends from the base layer 310 while maintaining a nanometer-size gap 322 a between the adjacent carbon nanowalls 322.

(Laser irradiation step S130)
In the laser irradiation step S130, the laser irradiation apparatus 120 is used to irradiate a predetermined region of the nanostructure layer 320 with a laser having a pulse width of less than 10 ⁻¹² seconds to leave the base layer 310, and the nanostructure layer This is a step of ablating 320.

  Here, the laser irradiation apparatus 120 irradiates two regions 324A and 324B spaced apart from each other in the nanostructure layer 320. Then, the regions 324A and 324B irradiated with the laser are in a state where only the base layer 310 remains on the substrate S.

  Thus, a sensor including the substrate S, the base layer 310 provided on the substrate S, and the nanostructure layer 320 formed in a predetermined region (a region other than the regions 324A and 324B) in the base layer 310. A structure 400 is manufactured.

  FIG. 6 is a diagram illustrating the sensor 500 manufactured using the sensor structure 400 and the conventional sensor 10.

  As shown in FIG. 6A, a metal paste 410 (for example, a gold paste) is applied to the regions 324A and 324B in the sensor structure 400. Then, the metal pastes 410 are connected to each other through the wiring 420. In addition, a measuring device 430 is provided on the wiring 420. The measuring device 430 measures a potential difference between the metal pastes 410 by passing a predetermined amount of current. That is, the regions 324A and 324B function as electrodes. Thus, the sensor 500 including the sensor structure 400, the metal paste 410, the wiring 420, and the measuring device 430 is manufactured.

  The upper part of the carbon nanowall 322 constituting the nanostructure layer 320 is not physically or electrically connected. On the other hand, as described above, the base layer 310 is continuously formed between the substrate S and the nanostructure layer 320 (carbon nanowall 322). Therefore, the carbon nanowalls 322 are physically and electrically communicated with each other through the base layer 310 (graphite layer) at the bottom thereof.

  A gap 322 a is disposed between the carbon nanowalls 322 constituting the nanostructure layer 320. The gap 322a is an insulator. For this reason, when nothing is attached to the nanostructure layer 320 (hereinafter referred to as “initial state”), the resistance value of the nanostructure layer 320 becomes extremely large. Therefore, in the initial state, the current flowing between the metal pastes 410 by the measuring device 430 almost passes through the base layer 310.

  On the other hand, when the object M adheres between the carbon nanowalls 322 (hereinafter referred to as “attachment state”), the carbon nanowalls 322 are electrically connected to each other (the electrical characteristics of the nanostructure layer 320 change), The resistance value of the nanostructure layer 320 is lowered. Therefore, the current flowing between the metal pastes 410 by the measuring device 430 passes through the base layer 310 and the carbon nanowall 322.

  That is, the potential difference (voltage value) in the initial state is different from the potential difference in the attached state. Therefore, by comparing the potential difference measured by the measuring device 430, it is possible to estimate whether or not the object M has adhered and what the object M is.

  Here, the object M is, for example, a gas such as hydrogen or methane, a protein, or the like, and the sensor 500 can be used as a gas sensor or a biosensor.

  As described above, the sensor manufacturing system 100 and the sensor manufacturing method can form the regions 324A and 324B of only the underlayer 310 (graphite layer) on both sides of the nanostructure layer 320 only by irradiating the laser. . Therefore, by using the regions 324A and 324B as electrodes, the main path through which current flows in the initial state can be the base layer 310.

  On the other hand, in the conventional sensor 10 shown in FIG. 6B, a metal paste 410 is applied on the nanostructure layer 320. Therefore, in the conventional sensor 10, the current flowing between the metal pastes 410 in the initial state passes through the carbon nanowall 322, the base layer 310, and the carbon nanowall 322. Here, in the conventional sensor 10, there are a plurality of carbon nanowalls 322 in contact with the metal paste 410. For this reason, the number of carbon nanowalls 322 in which current flows and the flow path are not stable. Therefore, in the conventional sensor 10, the fluctuation range of the measured value measured by the measuring device 430 becomes large. That is, the conventional sensor 10 has a problem that the noise of the measurement value increases and the signal-to-noise ratio (SNR) decreases.

  However, as described above, in the sensor 500 of the present embodiment, in the initial state, the current flowing between the metal pastes 410 by the measuring device 430 almost passes through the base layer 310. That is, the current flowing between the metal pastes 410 does not pass through the carbon nanowall 322. Therefore, the sensor 500 can reduce the fluctuation range of the measurement value measured by the measurement device 430. Thereby, the sensor 500 can reduce the noise of a measured value, and can improve an S / N ratio.

  Further, as described above, the underlayer 310 is a layer in which a metal is doped into graphite. Bondability between graphite and metal is not high. However, the bonding property between the regions 324A and 324B and the metal paste 410 can be improved by including the metal in the base layer 310. In addition, when the metal paste 410 is a gold paste, the metal doped into graphite is preferably gold.

(Example)
A silicon substrate was employed as the substrate S, and the graphite layer and the nanostructure layer 320 were formed using the film forming apparatus 110. Then, the laser was irradiated to the nano structure layer 320 (carbon nanowall 322) using the laser irradiation apparatus 120. The wavelength of the laser was 800 nm. The laser pulse width was 40 femtoseconds. The energy density of the laser was 1.3 × 10 ¹⁴ W / cm ² . The laser irradiation atmosphere was air, and the pressure of the irradiation atmosphere was atmospheric pressure.

  FIG. 7 is a diagram for explaining the results of the example. FIG. 7A and FIG. 7B are diagrams for explaining the height from the substrate S in the embodiment. FIG.7 (c) is an image which shows the result of having observed the Example with the scanning electron microscope (SEM). FIG. 7D is a partially enlarged image of the laser irradiation region in FIG.

  As shown in FIGS. 7A and 7B, the area irradiated with the laser (laser irradiation area) had a height from the substrate S of about 2.000 μm. On the other hand, the height from the substrate S was 3.000 μm or more and 4.000 μm or less at a location where the laser was not irradiated (location where the nanostructure layer 320 was maintained). Moreover, as shown in FIG.7 (c) and FIG.7 (d), it was confirmed that the graphite layer is maintained in the laser irradiation area | region.

  As mentioned above, although embodiment was described referring an accompanying drawing, it cannot be overemphasized that this indication is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims and that they naturally fall within the technical scope.

  For example, in the above-described embodiment, the case where the film forming apparatus 110 is a plasma CVD apparatus has been described as an example. However, the film forming apparatus 110 only needs to be able to form the graphite layer and the nanostructure layer 320 on the substrate S. For example, the film forming apparatus 110 may be configured with a CVD apparatus.

  Moreover, in the said embodiment, it demonstrated taking the case of the structure in which the board | substrate S contains the element which is easy to form a carbide | carbonized_material. However, there is no limitation on the material of the substrate.

  In the above-described embodiment, the configuration in which metal is doped only in the graphite layer has been described as an example. However, in addition to the graphite layer, the nanostructure layer 320 (carbon nanowall 322) may be doped with metal. Further, depending on the object M, the metal doped into the nanostructure layer 320 may be different from the metal doped into the graphite layer. Further, only the carbon nanowall (nanostructure layer) may be doped with metal. Furthermore, the graphite layer and the carbon nanowall (nanostructure layer) may not be doped with metal.

Further, according to the object M, the nanostructure layer 320 (carbon nanowall 322) may be doped with a nonmetallic element (including a metalloid element). For example, boron (B), carbon (C), nitrogen (N), silicon (Si), phosphorus (P), sulfur (S), germanium (Ge), arsenic (As), selenium (Se), bromine (Br ), Antimony (Sb), tellurium (Te), and iodine (I) may be doped into the nanostructure layer 320. Of the non-metallic elements, elements other than nitrogen (N) can be doped into the nanostructure layer 320 by sputtering in the second film-forming step S120, for example. Nitrogen (N) can be doped into the nanostructure layer 320 by, for example, mixing nitrogen gas (N ₂ ) with the reaction gas in the plasma CVD process (second film formation step S120).

  Moreover, in the said embodiment, in 1st film-forming process S110, it demonstrated and demonstrated the structure which dopes a metal to a graphite layer by sputtering. However, the metal doping is not limited to sputtering, but a vapor deposition process using an organic metal, a process of heating and depositing a metal, a CVD process, an organometallic gas (trimethylgallium, trimethylaluminum, etc.) or a metal chloride gas ( You may perform using the process made to react with a gallium chloride gas etc. and the intercalation process (process which immerses a graphite layer in the solution containing a metal).

  In the above-described embodiment, the configuration in which the carbon nanowall 322 is erected in the vertical direction from the surface of the substrate S has been described as an example. However, the carbon nanowall 322 only needs to be erected from the substrate S, and the angle is not limited.

  Moreover, in the said embodiment, the measuring apparatus 430 demonstrated and demonstrated the structure which measures the electrical potential difference between the metal paste 410 as an example. However, the measuring device 430 may measure the value of current flowing between the metal pastes 410.

  Moreover, in the said embodiment, the laser irradiation apparatus 120 demonstrated and demonstrated the structure which irradiates the laser to two area | region 324A, 342B spaced apart from each other in the nanostructure layer 320 as an example. However, the laser irradiation device 120 may irradiate the laser on one area. FIG. 8 is a diagram illustrating a sensor 600 according to a modified example. When the laser irradiation device 120 irradiates only one region 324C with a laser, the sensor 600 is manufactured by applying a metal paste 410 to the region 324C and the base layer 310 as shown in FIG. Similarly to the sensor 500, the sensor 600 of the modified example can use the region 324C as an electrode, so that the main path through which the current flows can be the base layer 310 in a state where the object M is not attached.

  Moreover, in the said embodiment, the laser irradiation apparatus 120 demonstrated as an example the structure provided with a beam homogenizer. However, a beam homogenizer is not essential.

  The present disclosure can be used for a sensor manufacturing system, a sensor manufacturing method, and a sensor that manufacture a sensor using carbon nanowalls.

DESCRIPTION OF SYMBOLS 100 Sensor manufacturing system 110 Film-forming apparatus 120 Laser irradiation apparatus 500 Sensor 600 Sensor

Claims (6)

A film forming apparatus for forming a graphite layer and a nanostructure layer including a plurality of carbon nanowalls on a substrate;
A laser irradiation apparatus for ablating the nanostructure layer while irradiating a predetermined region of the nanostructure layer with a laser having a pulse width of less than 10 ⁻¹² seconds to leave the graphite layer;
A sensor manufacturing system comprising:   2. The sensor manufacturing system according to claim 1, wherein the film forming apparatus is configured to dope a metal into one or both of the graphite layer and the carbon nanowall.   The sensor manufacturing system according to claim 1, wherein the laser irradiation device irradiates the laser to two regions of the nanostructure layer that are separated from each other.   The sensor manufacturing system according to claim 1, wherein the laser irradiation device includes a beam homogenizer. Forming a graphite layer on the substrate;
Forming a nanostructure layer comprising a plurality of carbon nanowalls on the graphite layer;
Irradiating a predetermined region of the nanostructure layer with a laser having a pulse width of less than 10 ⁻¹² seconds to ablate the nanostructure layer while leaving the graphite layer;
A method for manufacturing a sensor comprising: A substrate,
A graphite layer provided on the substrate;
A nanostructure layer comprising a plurality of carbon nanowalls formed in a predetermined region of the graphite layer;
Comprising a sensor.