US3798141A - Technique for electroetching thin film metallization - Google Patents

Technique for electroetching thin film metallization Download PDF

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Publication number
US3798141A
US3798141A US00298856A US3798141DA US3798141A US 3798141 A US3798141 A US 3798141A US 00298856 A US00298856 A US 00298856A US 3798141D A US3798141D A US 3798141DA US 3798141 A US3798141 A US 3798141A
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Prior art keywords
platinum
etching
gold
thin film
rhodium
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Expired - Lifetime
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US00298856A
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English (en)
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J Yahalom
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AT&T Corp
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Bell Telephone Laboratories Inc
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/02—Apparatus or processes for manufacturing printed circuits in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding
    • H05K3/06—Apparatus or processes for manufacturing printed circuits in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding the conductive material being removed chemically or electrolytically, e.g. by photo-etch process
    • H05K3/07—Apparatus or processes for manufacturing printed circuits in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding the conductive material being removed chemically or electrolytically, e.g. by photo-etch process being removed electrolytically
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F3/00—Electrolytic etching or polishing
    • C25F3/02—Etching
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • 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

Definitions

  • This invention relates to a technique for electrochemically etching thin film metallizations. More particularly, the present invention relates to a technique for selectively etching thin film metallization including noble metals by electrochemical means.
  • platinum has not proven as convenient to use as palladium, it has not evidenced the interdiffusion problem with gold.
  • platinum was found to be very diflicult to etch and the only material found suitable for this purpose has been aqua regia, a material which attacks photoresists. Further investigation revealed that pattern delineation of the platinum containing composite could only be effected by back sputtering, a technique which is economically undesirable and which often results in the deposition of residues. Still further, back sputtering could not be used in the fabrication of MOS devices due to the likelihood of damaging the dielectric. Accordingly, the platinum composites have been utilized primarily in the fabrication of bipolar devices. Recognizing these limitations, workers in the art have focused their interest upon the development of a technique suitable for pattern delineating all noble metals with a universal etchant.
  • the invention involves etching at least one thin film material selected from among gold, rhodium and platinum in a non-oxidizing electrolyte having a pH less than one by applying a potential difference between the sample to be etched and an auxiliary electrode so as to develop a potential on the sample with respect to a reference electrode which varies periodically between anupper and a lower value.
  • etching of a gold-transition metal metallization composite having a barrier layer selected from the group consisting of platinum and rhodium is effected selectively in an electrolyte comprising a non-oxidizing acid having a pH less: than one.
  • Composites may be etched in the described nianner in controllable fashion at a significantly higher rate than that attainable by conventional electroetching techniques, the metals being removed selectively by adjusting the height of the potential.
  • FIG. l is a schematic representation of a typical system suitable for use in the practice of the present invention.
  • FIG. 2 is a graphical representation on coordinates of pulse duration in seconds against etching rate in Angstroms per minute for a titanium-platinum-gold composite pulse etched in accordance with the present invention.
  • an etching vessel 11 having disposed therein thin filmj composite 12 comprising an insulating substrate 13 having deposited thereon a transition metal or glue layer 14; a noble metal 15 selected from among platinum and rhodium, and patterned gold layer 16.
  • An electrolyte 17 is employed in an amount sufiicient to cover the metallized composite.
  • Electrolyte 17 is a non-oxidizing acid having a pH less than one. Typical acids suitable for use in the practice of the present invention are hydrochloric, sulphuric, hydrofluoric, phosphoric and the like.
  • the electrical system employed includes contacting electrode 18 which is connected to layer 14, electrode 18 being insulated from electrolyte 17 by means of insulating sheath 19.
  • a second electrode 20 functions as the counter or auxiliary electrode in the system and is immersed in electrolyte 17.
  • the third electrode 21 is a conventional reference electrode, typically a calomel electrode, which serves to maintain the composite 12 at a controlled potential with respect to the electrolyte, thereby permitting control of the etching process.
  • Each of the electrodes is shown connected to a pulsing means 22, typically a potentiostat including a pulse generator.
  • the apparatus depicted in FIG.-;l is set up and etching initiated by applyingv a difference of potential between the sample and the auxiliary electrode so as to develop a potential on the sample with respect 'to the reference electrode which varies periodically between an upper and lower value.
  • this potential may range from 1450 to 1600 mv. (hydrogen scale) at the upper value and from 550 to 60 mv. (hydrogen scale) at the lower value.
  • the lower value may range from 55.0 to 240 mv. and from 240 to 60 mv. for rapid etching.
  • the described technique may be used selectively with respect to platinum, gold and rhodium.
  • the use of higher potentials ranging from 1450 to 1600 mv. results in the etching of gold, platinum and rhodium.
  • the use of higher potentials ranging from 1450 to 1600 mv. results in the etching of gold, platinum and rhodium.
  • the use of higher potentials ranging from 1450 to 1600 mv
  • rhodium may be etched selectively with respect to platinum and gold by maintaining the upper value of potential between 900 and 1100 mv. and rhodium and platinum selectively etched with respect to gold at upper potential values ranging from 1100 to 1450 mv. (all potential being on the hydrogen scale).
  • the upper limit of 1600 mv. is dictated by considerations relating to undesirable gas evolution.
  • the lower potential limit is determined by etching rate considerations.
  • the period of time 'that the sample is maintained at either the upper or lower potential may conveniently range from 1 to milliseconds, the shorter time periods corresponding with the higher etching rates and the converse. It has been found that platinum may he etched at 1 millisecond durations at the rate of 4000 A. per minute and rhodium at 2000 A. per minute. However at 10 millisecond durations etching of platinum may be effected at the rate of 500 A. per minute and rhodium at the rate of 250 A. per minute.
  • FIG. 2 there is shown a graphical representation on coordinates of duration of time that the sample is maintained at either the upper or lower potential with respect to the reference electrode versus etching rate in Angstroms per minute for a titaniumplatinum-gold thin film composite etched in a 25 percent hydrochloric acid solution to potentials (on the hydrogen scale) from -60 to 240 mv.
  • a one millisecond duration results in etching of platinum at 4000 A. per minute and at 10 milliseconds at 500 A. per minute.
  • removal of the base or glue layer may also be effected by lowering the potential to a constant negative value, or by etching to a potential between 500 and 300 mv. at durations ranging from 1 to 10 milliseconds, so resulting in a universal etching bath.
  • a final chemical etching step will, of course, be used as required to remove detached residues.
  • EXAMPLE 1 A composite comprising successively 500 A. titanium, 500 A. platinum and 10,000 A. of gold deposited upon a ceramic substrate member was immersed in an apparatus of the type shown in FIG. 1, a 25 weight percent hydrochloric acid solution having a pH of about 1 being employed as the electrolyte.
  • the auxiliary electrode was comprised of carbon and the reference electrode was a calomel electrode.
  • Etching was then effected by establishing a potential of -60 mv. on the sample with respect to the reference electrode for a duration of 1 millisecond and then establishing a potential of 1600 mv. for a duration of 1 millisecond. The procedure was continued successively until the gold was removed. Then, the procedure was repeated using a lower potential value of 60 mv. and an upper value of 1240 mv. to remove the platinum at a rate of 4000 A. per minute.
  • Example 2 The procedure of Example 1 was repeated using a duration of 10 milliseconds. The platinum was etched controllably at the rate of 500 A. per minute.
  • EXAMPLE 3 The procedure of Example 2 was repeated using a composite comprising 500 A. of rhodium rather than platinum, the rhodium being etched using a duration of 10 milliseconds at a rate of 250 A. per minute.
  • Technique for electrochemical etching of a thin film selected from the group consisting of gold, platinum and rhodium which comprises immersing said thin film together with an auxiliary electrode and a reference electrode in an electrolyte comprising an acid having a pH less than one and etching the thin film by applying a difference of potential between the thin film and the auxiliary electrode so as to devlop a potential on the thin film with respect to the reference electrode which varies periodically between an upper value ranging up to 1600 mv. and a lower value ranging down to 60 mv., the potentials being on the hydrogen scale, the upper value of the potential ranging from 900 to 1100 mv.
  • Technique for electrochemical etching of a goldtransition metal thin film composite having a noble metal selected from the group consisting of platinum and rhodium deposited intermediate the gold and the transition metal which comprises immersing the composite together with an auxiliary electrode and a reference electrode in an electrolyte comprising an acid having a pH less than one and etching the composite by applying a difference of potential between the composite and the auxiliary electrode so as to develop a potential on the composite with respect to the reference electrode which varies periodically between an upper value ranging up to 1600 mv. and a lower value ranging down to -60 mv., the potentials being on the hydrogen scale, the upper value of the potential ranging from 900 to 1100 mv.
  • a technique for pattern delineation of a thin film composite comprising an insulating substrate having deposited thereon a transition metal, a noble metal selected from the group consisting of platinum and rhodium and a patterned gold layer which comprises immersing the composite together with an auxiliary electrode and a reference electrode in an electrolyte comprising an acid having a pH less than one and etching the composite by applying a difference of potential between the composite and the auxiliary electrode so as to develop a potential on the composite with respect to the reference electrode which varies periodically between an upper value ranging up to 1600 mv. and a lower value ranging down to -60 mv., the potentials being on the hydrogen scale, the upper value of the potential ranging from 900 to 1100 mv.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Computer Hardware Design (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • ing And Chemical Polishing (AREA)
  • Weting (AREA)
  • Manufacturing Of Printed Circuit Boards (AREA)
US00298856A 1972-10-19 1972-10-19 Technique for electroetching thin film metallization Expired - Lifetime US3798141A (en)

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US29885672A 1972-10-19 1972-10-19

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US (1) US3798141A (enrdf_load_stackoverflow)
JP (1) JPS4974140A (enrdf_load_stackoverflow)
BE (1) BE806230A (enrdf_load_stackoverflow)
CA (1) CA1026704A (enrdf_load_stackoverflow)
DE (1) DE2351664B2 (enrdf_load_stackoverflow)
FR (1) FR2203890B1 (enrdf_load_stackoverflow)
GB (1) GB1408352A (enrdf_load_stackoverflow)
IT (1) IT999661B (enrdf_load_stackoverflow)
NL (1) NL157062B (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3898141A (en) * 1974-02-08 1975-08-05 Bell Telephone Labor Inc Electrolytic oxidation and etching of III-V compound semiconductors
US4125444A (en) * 1976-12-14 1978-11-14 Inoue-Japax Research Incorporated Electrochemical polishing method
US4206028A (en) * 1976-12-14 1980-06-03 Inoue-Japax Research Incorporated Electrochemical polishing system
WO2002030401A2 (en) 2000-10-11 2002-04-18 Microchips, Inc. Microchip reservoir devices and facilitated corrosion of electrodes
US20030217930A1 (en) * 2002-05-24 2003-11-27 Yufeng Luo Method and apparatus for electrochemical machining
US6875208B2 (en) 2001-05-31 2005-04-05 Massachusetts Institute Of Technology Microchip devices with improved reservoir opening

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL7609816A (nl) * 1976-09-03 1978-03-07 Philips Nv Werkwijze voor het vervaardigen van een lichaam voorzien met een goudpatroon en lichaam ver- vaardigd volgens de werkwijze.
DE3029277C2 (de) * 1980-08-01 1983-10-20 Siemens AG, 1000 Berlin und 8000 München Aufbau von Metallschichten

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3566358A (en) * 1968-03-19 1971-02-23 Bevier Hasbrouck Integrated multi-computer system

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3898141A (en) * 1974-02-08 1975-08-05 Bell Telephone Labor Inc Electrolytic oxidation and etching of III-V compound semiconductors
US4125444A (en) * 1976-12-14 1978-11-14 Inoue-Japax Research Incorporated Electrochemical polishing method
US4206028A (en) * 1976-12-14 1980-06-03 Inoue-Japax Research Incorporated Electrochemical polishing system
WO2002030401A2 (en) 2000-10-11 2002-04-18 Microchips, Inc. Microchip reservoir devices and facilitated corrosion of electrodes
WO2002030401A3 (en) * 2000-10-11 2003-01-16 Microchips Inc Microchip reservoir devices and facilitated corrosion of electrodes
US6773429B2 (en) 2000-10-11 2004-08-10 Microchips, Inc. Microchip reservoir devices and facilitated corrosion of electrodes
US6875208B2 (en) 2001-05-31 2005-04-05 Massachusetts Institute Of Technology Microchip devices with improved reservoir opening
US20030217930A1 (en) * 2002-05-24 2003-11-27 Yufeng Luo Method and apparatus for electrochemical machining
US7175752B2 (en) 2002-05-24 2007-02-13 Federal-Mogul Worldwide, Inc. Method and apparatus for electrochemical machining
US20070051618A1 (en) * 2002-05-24 2007-03-08 Yuefeng Luo Method and apparatus for electrochemical machining
US7850831B2 (en) 2002-05-24 2010-12-14 Federal Mogul World Wide, Inc. Method and apparatus for electrochemical machining

Also Published As

Publication number Publication date
DE2351664A1 (de) 1974-05-02
DE2351664B2 (de) 1975-09-18
BE806230A (fr) 1974-02-15
CA1026704A (en) 1978-02-21
IT999661B (it) 1976-03-10
GB1408352A (en) 1975-10-01
JPS4974140A (enrdf_load_stackoverflow) 1974-07-17
FR2203890B1 (enrdf_load_stackoverflow) 1976-07-23
NL157062B (nl) 1978-06-15
FR2203890A1 (enrdf_load_stackoverflow) 1974-05-17
NL7314162A (enrdf_load_stackoverflow) 1974-04-23

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