US3546036A - Process for etch-polishing sapphire and other oxides - Google Patents

Process for etch-polishing sapphire and other oxides Download PDF

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Publication number
US3546036A
US3546036A US556977A US3546036DA US3546036A US 3546036 A US3546036 A US 3546036A US 556977 A US556977 A US 556977A US 3546036D A US3546036D A US 3546036DA US 3546036 A US3546036 A US 3546036A
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Prior art keywords
etch
polishing
sapphire
gas
substrate
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US556977A
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English (en)
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Harold M Manasevit
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Boeing North American Inc
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North American Rockwell Corp
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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/16—Oxides
    • C30B29/22—Complex oxides
    • C30B29/26—Complex oxides with formula BMe2O4, wherein B is Mg, Ni, Co, Al, Zn, or Cd and Me is Fe, Ga, Sc, Cr, Co, or Al
    • 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
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S148/00—Metal treatment
    • Y10S148/051—Etching
    • 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
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S148/00—Metal treatment
    • Y10S148/15—Silicon on sapphire SOS

Definitions

  • the invention is directed to a process for improving the quality of surfaces of refractory inorganic oxide materials comprising etch-polishing of the surfaces of the material by the steps of heating the material to an elevated temperature and exposing the surface of the material to a fluoride containing gas.
  • This invention relates to a process for etch-polishing sapphire and other oxides and more particularly to a process using a gaseous fluoride etchant for etch-polishing sapphire and other oxides.
  • the quality of epitaxial films grown on substrate materials is determined by the quality of the substrate surface.
  • Previous processes for improving the surface includes the use of a diamond paste to polish the surface.
  • various size scratches, visible at high magnification (e.g. X400) remained on the surface of the sapphire after polishing. The presence of these scratches affects the nucleation mechanism, and hence, the quality of epitaxially grown silicone or other material deposited on the substrate surface.
  • An alumina buff process often is used to augment the diamond polishing for the purpose of removing the fine scratches.
  • the deeper scratches sometimes are filled with alumina powder, rather than being removed.
  • the surface appears to have a good quality, but during subsequent hydrogen etching and/or film growth the unremoved surface defects are exposed.
  • Some gas phase etchants previously have been used partially to etch the surface so as to improve its quality.
  • these prior art gaseous etchants removed the substrate material slowly and had a tendency to react with the material so as to degrade, rather than improve the substrate.
  • hydrogen gas has been used, but during time intervals which might be considered practical (perhaps up to one hour) the etch rate is very small.
  • Etching with hydrogen chloride also requires long time periods, and should a polycrystalline spacer be used to support a monocrystalline substrate, mass transfer has been noticed to occur from the spacer to the substrate.
  • etch-polish with a gas phase etchant at a relatively rapid rate just prior to forming the epitaxial growth layer on the substrate, and to accomplish this in the deposition chamber, so as to eliminate the need for handling the substrate between the etchpolishing and deposition steps.
  • etch-polishing process also can be used for purposes other than the cleaning of substrate materials. For example, it can be used to etchpolish the sides and ends of ruby laser rods.
  • the invention comprises etch-polishing the surface of a (single crystal) refractory inorganic oxide substarates such as sapphire, beryllium oxide, thorium oxide, zirconium oxide, spinels, chrysoberyl, etc. by exposing the material to a fluoride containing gas such as SP and SP During the period of exposure, the substrate is maintained at elevated temperature, most commonly between 1300 and 1600 (3., although lower temperatures may be used, depending upon the material to be etch-polished.
  • Carrier gases such as hydrogen helium argon or nitrogen as the diluent of the SP or SP gas, may be used to conduct the etchant to the substrate surface. Other inert gases also may be used as the diluent.
  • Yet another object of this invention is to provide a gas-phase process for etch-polishing the sides and ends of ruby (or other refractory inorganic oxide) laser rods.
  • FIG. 1 is an illustration of an apparatus which may be used in practicing the process described herein.
  • FIGS. 2, 3 and 4 are graphs showing typical values of Weight loss per unit area as a function of time for three different concentrations of SP etchant.
  • the refractory material 1 to be etchpolished is placed inside a vertical reactor 2, on a pedestal 3 and separated therefrom by spacer 4.
  • Pedestal 3 may be composed of a high density carbon, although silicon, molybdenum, or other materials which can be heated inductively and which will not introduce undesired impurities into the system could be substituted.
  • the spacer 4 optimally is composed of a form of the material to be etchpolished; this minimizes interaction between the spacer and the material to be etch-polished.
  • use of a spacer of alumina (A1 0 would be appropriate.
  • Pedestal 3 is suspended in an area surrounded by coil 5 which coil is activated by an RF source (not shown) to cause inductive heating of pedestal 3.
  • the system includes channel 6 opening into the chamber of reactor 2, which channel interconnects a source 7 of gas-phase etchant SP or SF The rate of flow of the etchant is controlled by valve 8 and monitored by flow-meter 9.
  • Channel 6 also connects a source 10 of carrier gas, which could be hydrogen, helium, argon or nitrogen or an inert gas. When SP is used, an inert gas such as He is the preferred carrier.
  • Valve 11 is used to control the flow of carrier gas, and the rate of flow is monitored on flow meter 12 gases from the reaction chamber 2 exit via exhaust channel 13 which is connected to exhaust means (not shown).
  • Channel 14 and associated valve 15 are provided to allow introduction of semiconductor deposition materials into chamber 2 subsequent to the etch-polishing process.
  • the invention is not limited to the particular apparatus shown and described but may include various reactor channel arrangements well known in the art for exposing substrates to gaseous environments.
  • the pedestal be located downstream from the material to be etch-polished to prevent reaction products of the pedestal material and the gaseous etchant from contaminating the material being etchpolished.
  • the above processes also can be used effectively to etch-polish fine-ground sapphire surfaces (about a 30 microinch finish) rather than diamond polished substrate materials. This has the dual advantages of minimizing work damage due to polishing and of reducing substrate costs considerably. Experience has indicated that exposure times in the order of five times that required for etchpolishing diamond polished surfaces are needed to accomplish such etch-polishing of fine-ground sapphire.
  • Table I below is included to indicate typical values of weight loss observed when 0.3 percent by volume SF in a helium diluent as used to etch-polish materials other than sapphire. As before, the data included are to be considered typical, and will vary depending on the configuration of the chamber, the type of carrier gas, flow rate, and exposure time used, the crystalline surface exposed to be etch-polished, and so forth.
  • SP sulfur hexafiuoride
  • a hydrogen diluent is used with SF very little etch-polishing of sapphire can be obtained under the same conditions which yield excellent etch-polishing by SP in a helium diluent.
  • FIGS. 2, 3 and 4 contain graphs showing the typical valves of sapphire weight loss per unit area as a function of time for three concentrations (0.22, 0.34, and 0.60 percent by volume, respectively) of SF in helium diluent, for pedestal temperatures of 1350 C., 1450 C. and 1550" C. in each case, arbitrary fiow rates of 2.5 liters per minute were used, with a reactor chamber 2 having a diameter of mm. a 1.5 inch diameter high density carbon pedestal 3, and a polycrystalline alumina spacer 4.
  • the material to be etch-polished should be exposed to the gaseous etchant for a period of time sufficient to remove a layer at least equal in thickness to the maximum depth scratch observed on the material subsequent to rough-or diamond-polishing.
  • an etch-polishing period may be selected to remove that thickness of material containing a substantial percentage of the defects.
  • a process for improving the quality of surfaces of a high temperature refractory inorganic oxide material selected from the group consisting of beryllium oxide, thorium dioxide, spinel or chrysoberyl comprising the steps of:
  • sulfur fluoride gas is selected from the group consisting of sulfur tetrafiuoride or sulfur hexafiuoride.
  • sulfur fluoride gas is selected from the group consisting of sulfur tetrafluoride or sulfur hexafluoride, said gas being in a diluent which is selected from the class consisting of helium, argon, nitrogen or an inert gas.
  • a process for improving the quality of the surfaces of an aluminum oxide material comprising the steps of: heating said material to an approximate temperature ranging between ll50 C. and 1600 C.; and exposing at least one of the surfaces of said material to a sulfur fluoride gas for a period of time sufl'icient to etch-polish same.
  • said sulfur fluoride gas is selected from the group consisting of sulfur tetrafluoride or sulfur hexafluoride. 6.
  • said sulfur fluoride gas is selected from the group consisting of sulfur tetrafluoride or sulfur hexafluoride, said gas being in a diluent which is selected from the group consisting of helium, argon, nitrogen or an inert gas.
  • a process for improving the quality of surfaces of a high temperature refractory aluminum oxide material comprising the steps of:
  • a process for improving the quality of surfaces of a high temperature refractory aluminum oxide material comprising the steps of:

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Mechanical Treatment Of Semiconductor (AREA)
  • Drying Of Semiconductors (AREA)
US556977A 1966-06-13 1966-06-13 Process for etch-polishing sapphire and other oxides Expired - Lifetime US3546036A (en)

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US55697766A 1966-06-13 1966-06-13

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US (1) US3546036A (ref)
BE (1) BE697181A (ref)
DE (1) DE1646804B2 (ref)
GB (1) GB1191172A (ref)
NL (1) NL6706449A (ref)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3661637A (en) * 1969-01-02 1972-05-09 Siemens Ag Method for epitactic precipitation of silicon at low temperatures
US3971684A (en) * 1973-12-03 1976-07-27 Hewlett-Packard Company Etching thin film circuits and semiconductor chips
US4011099A (en) * 1975-11-07 1977-03-08 Monsanto Company Preparation of damage-free surface on alpha-alumina
US4033743A (en) * 1974-03-22 1977-07-05 General Electric Company Chemically polished polycrystalline alumina material
US4038117A (en) * 1975-09-04 1977-07-26 Ilc Technology, Inc. Process for gas polishing sapphire and the like
US4052251A (en) * 1976-03-02 1977-10-04 Rca Corporation Method of etching sapphire utilizing sulfur hexafluoride
US4131496A (en) * 1977-12-15 1978-12-26 Rca Corp. Method of making silicon on sapphire field effect transistors with specifically aligned gates
US4425415A (en) 1981-08-03 1984-01-10 General Electric Company Etched beta"-alumina ceramic electrolyte
US4509990A (en) * 1982-11-15 1985-04-09 Hughes Aircraft Company Solid phase epitaxy and regrowth process with controlled defect density profiling for heteroepitaxial semiconductor on insulator composite substrates
US4753895A (en) * 1987-02-24 1988-06-28 Hughes Aircraft Company Method of forming low leakage CMOS device on insulating substrate
US4826300A (en) * 1987-07-30 1989-05-02 Hughes Aircraft Company Silicon-on-sapphire liquid crystal light valve and method
US20070188717A1 (en) * 2006-02-14 2007-08-16 Melcher Charles L Method for producing crystal elements having strategically oriented faces for enhancing performance

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040014327A1 (en) * 2002-07-18 2004-01-22 Bing Ji Method for etching high dielectric constant materials and for cleaning deposition chambers for high dielectric constant materials

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3366520A (en) * 1964-08-12 1968-01-30 Ibm Vapor polishing of a semiconductor wafer
US3392069A (en) * 1963-07-17 1968-07-09 Siemens Ag Method for producing pure polished surfaces on semiconductor bodies

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3392069A (en) * 1963-07-17 1968-07-09 Siemens Ag Method for producing pure polished surfaces on semiconductor bodies
US3366520A (en) * 1964-08-12 1968-01-30 Ibm Vapor polishing of a semiconductor wafer

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3661637A (en) * 1969-01-02 1972-05-09 Siemens Ag Method for epitactic precipitation of silicon at low temperatures
US3971684A (en) * 1973-12-03 1976-07-27 Hewlett-Packard Company Etching thin film circuits and semiconductor chips
US4033743A (en) * 1974-03-22 1977-07-05 General Electric Company Chemically polished polycrystalline alumina material
US4038117A (en) * 1975-09-04 1977-07-26 Ilc Technology, Inc. Process for gas polishing sapphire and the like
US4011099A (en) * 1975-11-07 1977-03-08 Monsanto Company Preparation of damage-free surface on alpha-alumina
US4052251A (en) * 1976-03-02 1977-10-04 Rca Corporation Method of etching sapphire utilizing sulfur hexafluoride
US4131496A (en) * 1977-12-15 1978-12-26 Rca Corp. Method of making silicon on sapphire field effect transistors with specifically aligned gates
US4425415A (en) 1981-08-03 1984-01-10 General Electric Company Etched beta"-alumina ceramic electrolyte
US4509990A (en) * 1982-11-15 1985-04-09 Hughes Aircraft Company Solid phase epitaxy and regrowth process with controlled defect density profiling for heteroepitaxial semiconductor on insulator composite substrates
US4753895A (en) * 1987-02-24 1988-06-28 Hughes Aircraft Company Method of forming low leakage CMOS device on insulating substrate
US4826300A (en) * 1987-07-30 1989-05-02 Hughes Aircraft Company Silicon-on-sapphire liquid crystal light valve and method
US20070188717A1 (en) * 2006-02-14 2007-08-16 Melcher Charles L Method for producing crystal elements having strategically oriented faces for enhancing performance

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Publication number Publication date
NL6706449A (ref) 1967-12-14
DE1646804B2 (de) 1972-03-02
DE1646804A1 (de) 1971-09-02
GB1191172A (en) 1970-05-06
BE697181A (ref) 1967-10-02

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