US3443311A - Thin film distributed rc network - Google Patents

Thin film distributed rc network Download PDF

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Publication number
US3443311A
US3443311A US590805A US3443311DA US3443311A US 3443311 A US3443311 A US 3443311A US 590805 A US590805 A US 590805A US 3443311D A US3443311D A US 3443311DA US 3443311 A US3443311 A US 3443311A
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Prior art keywords
layer
tantalum
film
thin film
low density
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Expired - Lifetime
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US590805A
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English (en)
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Walter Worobey
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AT&T Corp
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Bell Telephone Laboratories Inc
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/01—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate comprising only passive thin-film or thick-film elements formed on a common insulating substrate
    • H01L27/016—Thin-film circuits
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/40—Structural combinations of fixed capacitors with other electric elements, the structure mainly consisting of a capacitor, e.g. RC combinations
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N97/00—Electric solid-state thin-film or thick-film devices, not otherwise provided for
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/49082—Resistor making
    • Y10T29/49099—Coating resistive material on a base

Definitions

  • This invention relates to thin film structures. More particularly, the present invention relates to a novel thin film distributed RC structure.
  • trim anodization technique is not readily applicable to thin film distributed RC networks (which offer several advantages over the lumped thin film RC network, namely, ease in synthesizing a function by the elimination of components, etc.) in which a film capacitor is superpositioned upon a film resistor due to the fact that the superposed counterelectrode prevents trim anodization of the underlying resistor path.
  • this prior art limitation is effectively obviated by a novel structure comprising a thin film capacitor having a low density tantalum counterelectrode of a desired resistive configuration.
  • the described structure readily lends itself to precise adjustment of the RC product by trim anodization of the low density tantalum layer, so resulting in the desired frequency response.
  • the novel structures described herein are obtained by preparing a thin film capacitor by conventional techniques, the counterelectrode comprising low density tantalum obtained by cathodic sputtering techniques. Thereafter, conventional photolithographic methods are employed to generate the desired resistive configuration.
  • FIG. 1 is a cross-sectional view of a substrate with a layer of a film-forming metal deposited thereon;
  • FIG. 2 is a perspective view of the body of FIG. 1 after the generation therein of a desired pattern
  • FIG. 3 is a cross-sectional view of the body of FIG. 2 after anodization
  • FIG. 4 is a cross-sectional view of the body of FIG. 3 after deposition thereon of a counterelectrode and the generation therein of a desired pattern;
  • FIG. 5 is a cross-sectional view of the body of FIG. 4 after the trim anodization of the top layer thereof;
  • FIG. 6 is a plan view of the body of FIG. 5.
  • FIG. 1 there is shown a substrate upon which a metallic pattern is to be produced in accordance with the present invention.
  • Preferred substrate materials suitable for this purpose are glazed ceramics, glasses and so forth.
  • the first step in fabricating a structure in accordance with the invention involves cleansing the substrate by conventional techniques well known to those skilled in the art. Following the cleansing step, a layer of a film-forming metal 12 is deposited upon a substrate 11 by any conventional procedure as, for example, cathodic sputtering, vacuum evaporation and so forth, as described by L. Holland in Vacuum Deposition of Thin Films, J. Wiley & Sons, 1956.
  • the film-forming metals of interest herein are those whose oxides are known to be excellent dielectric ice materials and include tantalum, aluminum, niobium, titanium zirconium and hafnium.
  • the minimum thickness of the layer deposited upon the substrate is dependent upon two factors. The first of these is the thickness of the metal which is converted into the oxide form during the subsequent anodizing step. The second factor is the minimum thickness of unoxidized metal remaining after anodization commensurate with the maximum resistance which can be tolerated in the film-forming metal electrode. It has been determined that the preferred minimum thickness of the metal electrode is approximately 1000 A. There is no maximum limit on this thickness, although little advantage is gained by the increase above 10,000 A.
  • a suitable pattern is generated in layer 12 by conventional photoengraving techniques, so resulting in the structure shown in perspective in FIG. 2.
  • a suitable procedure is employed to mask out terminal area 13 such as the use of a grease.
  • FIG. 2 is anodized in an appropriate electrolyte, so resulting in the formation of a dielectric oxide layer 14 on the bottom electrode 12.
  • the voltage at which the anodizing is conducted is primarily determined by the voltage at which the structure is to be operated. Suitable electrolytes for this purpose are oxalic acid, citric acid, and so forth. Backetching and reanodizing may then be employed for the purpose of eliminating defects in the dielectric film.
  • the grease is removed from terminal area 13, so resulting in the structure shown in FIG. 3.
  • the next step in the fabrication of a distributed RC network in accordance with the invention involves the deposition of a low density tantalum layer upon the structure of FIG. 3.
  • the term low density tantalum is defined as tantalum evidencing a density considerably less than the bulk density of 16 grams cm.
  • An optimum has been found to correspond with the range of 10- 12 grams cm. It has been determined that tantalum of normal density results in structures evidencing high leakage currents and numerous short circuits. It has been theorized that such behavior is caused by damage done to the dielectric oxide layer by the impinging high energy tantalum atoms. Accordingly, it is essential that the tantalum film deposited be of low density, that is, produced by means such that essentially no damage occurs to the anodic oxide film.
  • the low density tantalum films required herein may only be obtained by cathodic sputtering techniques utilizing sputtering voltages ranging from 8002500 volts and partial pressures of sputtering gases ranging from 10-100 millitorr. Deviations from the noted extrema fail to generate the required glow discharge or result in the production of normal density tantalum. It will be understood by those skilled in the art that in addition to an inert gas such as argon, reactive gases may be employed in the sputtering reaction, oxygen and nitrogen being prime examples thereof.
  • a resistor pattern 15 (FIG. 4) is generated therein by conventional photoengraving techniques and terminals 16 defined.
  • FIG. 4 is subjected to trim anodization in order to obtain the desired frequency response, conventional anodization techniques being employed.
  • the resultant structure including oxide film 17 is shown in cross-sectional view in FIG. 5 and in plan view in FIG. 6.
  • Example A 1" x 3" glass microscope slide was cleaned with ultrasonic detergent washes and boiling hydrogen peroxide in accordance with conventional techniques. Thereafter, the substrate was positioned in a cathodic sputtering apparatus and a layer of tantalum 4000 A. in thickness deposited at 5000 volts and 300 milliamperes employing conventional techniques. Next, the substrate was subjected to conventional photoengraving techniques to define the desired pattern. Following, the tantalum layer was anodized in a 0.01 percent aqueous solution of citric acid, a constant current phase of 1 milliampere cm. being employed until a voltage of 130 volts was attained. At this point the assembly was left to anodize for 30 minutes at this maximum voltage.
  • the assembly was backetched for five seconds at 75 volts in a 0.01 percent solution of aluminum chloride in methanol in order to eliminate defects in the tantalum pentoxide dielectric layer. Then the assembly was reanodized for 30 minutes at the original anodizing voltage. Next, low density tantalum was deposited upon the anodized layer by cathodic sputtering techniques at 1500 volts and 300 milliamperes with an argon pressure of 35 millitorr. Sputtering was continued for 40 minutes, so resulting in a low density counterelectrode 1800 A. in thickness.
  • the next step in the fabrication of the distributed network involved defining the resistor pattern including terminals in the counterelectrode coating by conventional photoengraving techniques, thereby resulting in a structure similar to that shown in FIG. 4.
  • the resultant structure evidenced a capacitance of 0.10 microfarad Cm. a forward breakdown voltage of 23 volts, a reverse breakdown voltage of 22 volts (breakdown voltage being defined as the voltage at which the current drawn while charging the device at 1 volt per second reaches twice its initial charge current), and a leakage current of 1.5 X amperes at volts.
  • the frequency response of the network is next measured typically in terms of output voltage/ input voltage against frequency or in terms of phase difference between output and input against frequency. As the frequency response will not necessarily be that desired at a given frequency,
  • anodization of the top resistor may be effected until the frequency response measured equals that desired.
  • a method for the fabrication of a thin film distributed RC network which comprises the steps of (a) depositing a layer of a film-forming metal upon a substrate by condensation techniques, (b) anodizing said film-forming metal whereby there is formed an anodic oxide layer, (c) depositing a layer of low density tantalum evidencing a density less than 14 grams cm? upon said anodic oxide layer by cathodic sputtering techniques, the voltages ranging from 8002500 volts and partial pressures of sputtering gas ranging from 10-100 millitorr, and (d) generating a desired resistor pattern in said low density tantalum layer.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Manufacturing & Machinery (AREA)
  • Fixed Capacitors And Capacitor Manufacturing Machines (AREA)
  • Physical Vapour Deposition (AREA)
US590805A 1966-10-31 1966-10-31 Thin film distributed rc network Expired - Lifetime US3443311A (en)

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US59080566A 1966-10-31 1966-10-31

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US3443311A true US3443311A (en) 1969-05-13

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US (1) US3443311A (xx)
BE (1) BE705351A (xx)
DE (1) DE1639061B1 (xx)
FR (1) FR1541382A (xx)
GB (1) GB1209781A (xx)
MY (1) MY7400043A (xx)
NL (1) NL6714773A (xx)
SE (1) SE318648B (xx)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3615760A (en) * 1969-04-14 1971-10-26 Bell Telephone Labor Inc Calcium oxide-aluminum oxide-silicon dioxide ceramic substrate material for thin film circuits
US3784951A (en) * 1968-05-22 1974-01-08 Bell Telephone Labor Inc Thin film resistors
US3993967A (en) * 1975-03-31 1976-11-23 Western Electric Company, Inc. Resistance-capacitance network
US4280889A (en) * 1976-03-11 1981-07-28 Honeywell Inc. Solid state ion responsive and reference electrodes
EP0117008A2 (en) * 1983-02-22 1984-08-29 Philips Electronics Uk Limited Analogue wave filter device
US5311710A (en) * 1992-03-11 1994-05-17 Eaton Jay S Portable curing cell
US5598131A (en) * 1995-11-16 1997-01-28 Emc Technology, Inc. AC coupled termination
CN106024379A (zh) * 2016-05-12 2016-10-12 中国电子科技集团公司第四十研究所 一种梁式引线电容的加工方法

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2513859C2 (de) * 1975-03-27 1981-11-12 Siemens AG, 1000 Berlin und 8000 München Verfahren zum Herstellen eines Kondensator-Widerstands-Netzwerks
DE3024030A1 (de) * 1980-06-26 1982-01-14 Siemens AG, 1000 Berlin und 8000 München Rc-netzwerk in form einer folienschaltung
FR2505070B1 (fr) * 1981-01-16 1986-04-04 Suwa Seikosha Kk Dispositif non lineaire pour un panneau d'affichage a cristaux liquides et procede de fabrication d'un tel panneau d'affichage

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2694185A (en) * 1951-01-19 1954-11-09 Sprague Electric Co Electrical circuit arrangement
US3109983A (en) * 1957-05-02 1963-11-05 Glenn F Cooper Circuits with distributed characteristics
US3205555A (en) * 1961-11-07 1965-09-14 Western Electric Co Methods of making printed circuit components
US3239731A (en) * 1964-04-21 1966-03-08 Hughes Aircraft Co Self-healing thin-film capacitor
US3330696A (en) * 1967-07-11 Method of fabricating thin film capacitors

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3330696A (en) * 1967-07-11 Method of fabricating thin film capacitors
US2694185A (en) * 1951-01-19 1954-11-09 Sprague Electric Co Electrical circuit arrangement
US3109983A (en) * 1957-05-02 1963-11-05 Glenn F Cooper Circuits with distributed characteristics
US3205555A (en) * 1961-11-07 1965-09-14 Western Electric Co Methods of making printed circuit components
US3239731A (en) * 1964-04-21 1966-03-08 Hughes Aircraft Co Self-healing thin-film capacitor

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3784951A (en) * 1968-05-22 1974-01-08 Bell Telephone Labor Inc Thin film resistors
US3615760A (en) * 1969-04-14 1971-10-26 Bell Telephone Labor Inc Calcium oxide-aluminum oxide-silicon dioxide ceramic substrate material for thin film circuits
US3993967A (en) * 1975-03-31 1976-11-23 Western Electric Company, Inc. Resistance-capacitance network
US4280889A (en) * 1976-03-11 1981-07-28 Honeywell Inc. Solid state ion responsive and reference electrodes
EP0117008A2 (en) * 1983-02-22 1984-08-29 Philips Electronics Uk Limited Analogue wave filter device
EP0117008A3 (en) * 1983-02-22 1986-05-14 Philips Electronics Uk Limited Analogue wave filter device
US5311710A (en) * 1992-03-11 1994-05-17 Eaton Jay S Portable curing cell
US5598131A (en) * 1995-11-16 1997-01-28 Emc Technology, Inc. AC coupled termination
CN106024379A (zh) * 2016-05-12 2016-10-12 中国电子科技集团公司第四十研究所 一种梁式引线电容的加工方法

Also Published As

Publication number Publication date
DE1639061B1 (de) 1971-08-26
SE318648B (xx) 1969-12-15
BE705351A (xx) 1968-03-01
FR1541382A (fr) 1968-10-04
GB1209781A (en) 1970-10-21
MY7400043A (en) 1974-12-31
NL6714773A (xx) 1968-05-01

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