EP0429296A2 - Dielektrischer Heterofilm mit extrem niedrigem spezifischem Widerstand - Google Patents

Dielektrischer Heterofilm mit extrem niedrigem spezifischem Widerstand Download PDF

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Publication number
EP0429296A2
EP0429296A2 EP90312659A EP90312659A EP0429296A2 EP 0429296 A2 EP0429296 A2 EP 0429296A2 EP 90312659 A EP90312659 A EP 90312659A EP 90312659 A EP90312659 A EP 90312659A EP 0429296 A2 EP0429296 A2 EP 0429296A2
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EP
European Patent Office
Prior art keywords
heterofilm
film
polarized
thin
dielectric
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP90312659A
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English (en)
French (fr)
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EP0429296B1 (de
EP0429296A3 (en
Inventor
Taro Hino
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pioneer Corp
SWCC Corp
Original Assignee
Pioneer Electronic Corp
Showa Electric Wire and Cable Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Pioneer Electronic Corp, Showa Electric Wire and Cable Co filed Critical Pioneer Electronic Corp
Publication of EP0429296A2 publication Critical patent/EP0429296A2/de
Publication of EP0429296A3 publication Critical patent/EP0429296A3/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/02—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient
    • H01C7/021—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient formed as one or more layers or coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/10—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material voltage responsive, i.e. varistors

Definitions

  • the present invention relates to an ultra-low resistivity heterofilm which has a hetero-structure.
  • an ultra-low resistivity heterofilm having a hetero-­structure composed of polarized and non-polarized Langmuir-­Blodgett (LB) films stacked on one another and sandwiched between conductive films, the ultra-low resistivity heterofilm having a resistance value not higher than that of metal in the direction of the film surface thereof at a temperature not lower than room temperature.
  • LB Langmuir-­Blodgett
  • the polarized film(s) may be stacked on the non-­polarised film(s) or vice-versa and the hetero-structure sandwiched between conductive films so that the resistance of the film in the direction of the film surface becomes much lower than that of metal films.
  • a dielectric is also an insulator.
  • a dielectric material according to the invention which shows a resistivity much lower than metals at a temperature no lower than room temperature has nor previously existed.
  • a two-­dimensional potential well having a depth of several tens of Angstroms ( ⁇ ) can be formed by polarised and non-­polarised heterofilms and the potential well filled with an electron gas, generation of a two-dimensional low resistivity potential well can be expected.
  • the Z-type or A-type LB film can be used as a polarized film. It has large polarization substantially the same as saturation polarization of a ferroelectric even if no voltage is applied. In order to form a uniform potential well over a large area, it is necessary to smooth a surface on which a film is deposited. To this end, a SiO2 film on a silicon wafer can be used. Also, Ta2O5 film, ZrO2 film, glass substrate, and plastic substrate can be used.
  • Fig. 1 is a schematic view showing an embodiment of the dielectric ultralow resistivity heterofilm according to the present invention
  • Fig. 2 is a sectional view taken on line II-II of Fig. 1
  • Fig. 3 is a schematic view of the resistance measurement of the ultralow resistivity heterofilm according to the present invention
  • Fig. 4 is a view showing the voltage drop characteristics of the ultralow resistivity heterofilm according to the present invention
  • Fig. 5 is a view showing the voltage characteristics of a sample in which the ultralow resistivity heterofilm according to the present invention is not existing
  • Fig. 6 is a view showing the resistance characteristics of the ultralow resistivity heterofilm according to the present invention
  • Fig. 1 is a schematic view showing an embodiment of the dielectric ultralow resistivity heterofilm according to the present invention
  • Fig. 2 is a sectional view taken on line II-II of Fig. 1
  • Fig. 3 is a schematic view of the resistance measurement of the ultralow resistivity heterofilm according to the present invention
  • Fig. 7 is a view showing a comparison of the resistivity between the ultralow resistivity heterofilm according to the present invention and metal;
  • Fig. 8 is a view showing the temperature characteristics of the ultralow resistivity heterofilm according to the present invention; and
  • Fig. 9 is a view showing the switching characteristics of the ultralow resistivity heterofilm according to the present invention.
  • a thin evaporated film 3 of aluminum is formed on a silicon wafer 1 having, on its surface, an insulating SiO2 film 2 (thickness: about 5000 ⁇ ) as shown in Figs. 1 and 2.
  • the thickness and width of the evaporated Al film 3 are several hundreds ⁇ and 10 mm respectively, and the resistance value thereof measured across its opposite ends separated away by 30 mm from each other is about 600 ⁇ .
  • the evaporated Al film 3 is coated, by an LB method, with an LB heterofilm 4 which is composed of an arachidic acid LB film 4-a constituted by 4-6 single molecular layers and an LB film 4-b of 2-pentadecyl-7,7′,8,8′ tetracyanoquinodimethane (C15 ⁇ TCNQ) constituted by 4-6 single molecular layers.
  • the LB heterofilm 4 is coated with a thin evaporated film 5 of gold so that the dielectric ultralow resistivity heterofilm having a structure of [Al / LB heterofilm / Au] is formed with respect to the perpendicular to the LB heterofilm 4 according to the present invention.
  • the evaporated Al film and Au film are short-circuited so that potentials of the Al and Au films are maintained in equipotentially.
  • nine gold electrodes 6 are evaporated on the Au film 5, as the measurement terminals.
  • the arachidic acid LB film non-polarized Y-type film
  • the LB film of C15 ⁇ TCNQ polarized Z-type film
  • Fig. 3 shows a circuit for measuring resistivity by using a four-point probe technique.
  • a current is made to flow into/from a power source 8 through the outermost pair of electrodes 6-1 and 6-9 of the nine gold electrodes formed, through evaporation, on the dielectric ultra low resistivity heterofilm of the present invention, and a voltage drop v across another pair of electrodes 6-a and 6-b is measured by a voltmeter 10 to thereby obtain the resistance value of the dielectric ultralow resistivity heterofilm across the electrodes 6-a and 6-b.
  • the internal resistance of the voltmeter 10 is sufficiently high, and therefore the voltage drop v across the electrodes 6-a and 6-b can be accurately measured.
  • An ammeter 9 measures a current I flowing across the outermost electrodes 6-1 and 6-9.
  • Fig. 4 shows voltage drops among nine electrodes with currents of 0.16, 0.55 and 1.1 A as parameters, measured with respect to samples (Si-5L) of the dielectric ultralow resistivity heterofilm using the LB heterofilm constituted by the arachidic acid LB film and the C15 ⁇ TCNQ LB film each constituted by five single molecular layers (5L) according to the present invention.
  • the voltage drop is generally small, and when the voltage drop across adjacent electrodes is converted into a resistance value by using the expression (1), the resistance value is about 10 ⁇ 2 to 10 ⁇ 3 ⁇ while the value varies slightly depending on specific positions of the adjacent. electrodes.
  • the voltage drop is large across the electrodes 6-1 and 6-2 and across the electrodes 6-8 and 6-9, which may be caused by the contact resistance between the electrode and the LB film.
  • Fig. 5 shows voltage drops measured with respect to samples (Si-0L) in which only the LB heterofilm is eliminated from the sample shown in Figs. 1 and 2.
  • the resistance is about 28 ⁇ and the resistance value across adjacent electrodes is 4.4 ⁇ . This resistance value is substantially equal to that of the evaporated film of Al/Au just underneath the electrodes.
  • Fig. 6 shows a comparison of the resistance value across adjacent electrode terminals obtained from the results of Figs. 4 and 5 between the Si-0L having no LB heterofilm and Si-3L, Si-4L, and Si-5L each having the LB heterofilm.
  • the resistance value is reduced to 10 ⁇ 3 times only by interposition of the LB film having only a thickness of 189 ⁇ (Si-3L), 252 ⁇ (Si-4L), or 315 ⁇ (Si-5L) between the Al and Au evaporated films. This fact shows that the current passes in the inside of the surface of the very thin LB heterofilm.
  • the resistivity of the LB heterofilm can be obtained from the thickness, the width of the electrode, and the interval between the electrodes.
  • Fig. 7 shows the values of the resistivity plotted with respect to the current flowing in the LB film. The values within a range of 10 ⁇ 8 to 10 ⁇ 9 ⁇ cm were obtained, and each of the values was 10 ⁇ 3 ⁇ 10 ⁇ 4 times the illustrated value of metal (M) (about 10 ⁇ 5 ⁇ cm).
  • the dielectric heterofilm having the LB film according to the present invention has a resistance value much lower than that of metal.
  • Fig. 8 shows an example as to the sample of Si-4L.
  • the temperature of the silicon substrate was measured a thermocouple.
  • the resistivity is about 8.6 x 10 ⁇ 8 ⁇ cm (4L-1).
  • the temperature rise is caused by heat generated from the sample in a way of making an applied voltage high.
  • current values at various temperatures are shown (4L-2). From this experiment, it can clearly be seen that no current passes the silicon wafer of the substrate. This is because the resistivity of silicon rapidly decreases with temperature and therefore if the current passes in the silicon wafer, the resistivity cannot be kept constant as illustrated in the drawing but it must decrease with the temperature.
  • a current of about 1A is flowing in the LB ultralow resistivity heterofilm according to the present invention as shown in Fig. 8, and if converted, the current value corresponds to a current density having a large value of 400,000 A/cm2. Further, at this time, the temperature rises to 80 °C as shown in Fig. 8. This LB heterofilm, however, was never damaged. Moreover, even if the applied voltage was further increased in order to increase the current, a switching phenomenon as shown in Fig. 9 was caused to thereby rapidly decrease the current, and the current did not increase more.
  • Fig. 9 shows an example of the switching phenomenon, and shows a current I (5L-8) and a voltage drop (5L-9) between the adjacent electrode terminals 6-8 and 6-9, with respect to an applied voltage V.
  • the current rapidly falls from 1.3A to 3 x 10 ⁇ 4A, and at the same time the voltage drop rises to 15.5V.
  • the voltage drop is substantially equal to a voltage applied from the power source to the sample at this point of time. If the applied voltage is lowered, the current rapidly increases again (at the point of the applied voltage of 2V) so as to return to the original value. At the same time, also the resistance value decreases so as to return to the original one.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Ceramic Engineering (AREA)
  • Physical Vapour Deposition (AREA)
  • Non-Insulated Conductors (AREA)
  • Thermistors And Varistors (AREA)
EP19900312659 1989-11-20 1990-11-20 Dielektrischer Heterofilm mit extrem niedrigem spezifischem Widerstand Expired - Lifetime EP0429296B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP299563/89 1989-11-20
JP1299563A JP2884357B2 (ja) 1989-11-20 1989-11-20 誘電体へテロ超低抵抗膜

Publications (3)

Publication Number Publication Date
EP0429296A2 true EP0429296A2 (de) 1991-05-29
EP0429296A3 EP0429296A3 (en) 1992-04-29
EP0429296B1 EP0429296B1 (de) 1996-01-10

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EP19900312659 Expired - Lifetime EP0429296B1 (de) 1989-11-20 1990-11-20 Dielektrischer Heterofilm mit extrem niedrigem spezifischem Widerstand

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EP (1) EP0429296B1 (de)
JP (1) JP2884357B2 (de)
DE (1) DE69024760T2 (de)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013000028A (ja) 2011-06-14 2013-01-07 Makita Corp 電動芝刈機
JP5694065B2 (ja) 2011-06-14 2015-04-01 株式会社マキタ 電動芝刈機
JP5689753B2 (ja) 2011-06-14 2015-03-25 株式会社マキタ 電動芝刈機

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0165111A1 (de) * 1984-05-10 1985-12-18 Commissariat A L'energie Atomique Elektrisch leitfähige Folien mit zumindest einer monomolekularen Schicht eines organischen Energieüberführungskomplexes und Verfahren zur Herstellung desselben
JPS63280460A (ja) * 1987-05-13 1988-11-17 Hitachi Ltd 記憶素子
JPH01209767A (ja) * 1988-02-18 1989-08-23 Canon Inc 電気・電子デバイス素子

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0165111A1 (de) * 1984-05-10 1985-12-18 Commissariat A L'energie Atomique Elektrisch leitfähige Folien mit zumindest einer monomolekularen Schicht eines organischen Energieüberführungskomplexes und Verfahren zur Herstellung desselben
JPS63280460A (ja) * 1987-05-13 1988-11-17 Hitachi Ltd 記憶素子
JPH01209767A (ja) * 1988-02-18 1989-08-23 Canon Inc 電気・電子デバイス素子

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 13, no. 109 (E-727)15 March 1989 & JP-A-63 280 460 ( HITACHI ) 17 November 1988 *
WORLD PATENTS INDEX LATEST Derwent Publications Ltd., London, GB; AN 89-288225 & JP-A-1 209 767 (CANON) 23 August 1989 *

Also Published As

Publication number Publication date
EP0429296B1 (de) 1996-01-10
JPH03160759A (ja) 1991-07-10
DE69024760T2 (de) 1996-08-29
JP2884357B2 (ja) 1999-04-19
DE69024760D1 (de) 1996-02-22
EP0429296A3 (en) 1992-04-29

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