USRE29336E - Method of etching a surface of a substrate comprising LiTaO3 and chemically similar materials - Google Patents
Method of etching a surface of a substrate comprising LiTaO3 and chemically similar materials Download PDFInfo
- Publication number
- USRE29336E USRE29336E US05/751,926 US75192676A USRE29336E US RE29336 E USRE29336 E US RE29336E US 75192676 A US75192676 A US 75192676A US RE29336 E USRE29336 E US RE29336E
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- United States
- Prior art keywords
- etching
- mixture
- substrate
- litao
- molal
- Prior art date
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/53—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone involving the removal of at least part of the materials of the treated article, e.g. etching, drying of hardened concrete
- C04B41/5338—Etching
- C04B41/5353—Wet etching, e.g. with etchants dissolved in organic solvents
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
- C04B41/91—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics involving the removal of part of the materials of the treated articles, e.g. etching
Definitions
- This invention relates to a method of etching a surface of a substrate comprising LiTaO 3 and chemically similar materials and more particularly, to a method of etching LiTaO 3 with a mixture comprising hydrofluoric acid and sulfuric acid.
- LiTaO 3 lithium tantalate
- LiTaO 3 lithium tantalate
- An inherent problem in the use of LiTaO 3 has been the etching and polishing of this material.
- Lithium tantalate (LiTaO 3 ) can be etched with an aqueous mixture consisting of HNO 3 and HF.
- the etching can only be carried out at a reasonable rate at the boiling temperature of the mixture.
- the polishing of LiTaO 3 the HNO 3 -HF mixture does not polish a surface of LiTAO 3 so that optical inspection thereof for surface and interior defects is possible.
- An etchant which both etches the LiTaO 3 and polishes a surface thereof at a reasonable rate at a moderate temperature is therefore desirable and a method of employing such an etchant is an object of this invention.
- the present invention is directed to a method of etching a surface of a substrate comprising LiTaO 3 and chemically similar materials and more particularly, to a method of etching LiTaO 3 with a mixture comprising hydrofluoric acid and sulfuric acid.
- the method comprises contacting a surface of a substrate, comprising lithium tantalate (LiTaO 3 ) with a mixture comprising hydrofluoric acid and sulfuric acid whereby etching thereof occurs. Additionally, the mixture has a polishing effect on the etched surface.
- a substrate comprising lithium tantalate (LiTaO 3 )
- a mixture comprising hydrofluoric acid and sulfuric acid whereby etching thereof occurs. Additionally, the mixture has a polishing effect on the etched surface.
- the present invention is based upon the discovery of a unique chemical system for etching lithium tantalate and chemically similar compounds such as lithium niobate (LiNbO 3 ) and barium titanate.
- the etching system comprises a mixture comprising hydrofluoric acid, HF and sulfuric acid, H 2 SO 4 , contained in at least one suitable liquid solvent carrier.
- the solvent carrier may be either an aqueous or nonaqueous liquid.
- a preferred carrier solvent is water.
- concentrations of the respective components, HF and H 2 SO 4 employed depend on the rate of etch desired at a particular temperature.
- a preferred mixture concentration for 49 weight percent aqueous HF and 97 weight percent aqueous H 2 SO 4 typically ranges from about 0.40 to about 0.90 volume fraction of 49 weight percent aqueous HF (about 42.172 moles of HF/1000 gms. H 2 O, 40.173 moles of H 2 SO 4 /1000 gms. H 2 O to about 47.535 moles/1000 gms. H 2 O and 3.354 moles/1000 gms. H 2 O, respectively).
- a substrate to be treated i.e., comprising LiTaO 3
- the temperature of the etching solution is maintained at a temperature between room temperature to the boiling point of the particular mixture employed. In this regard, the temperature selected depends upon the parameters such as the etching mixture employed and the etch rate desired.
- a suitable solvent e.g., water
- exposure to the HF-H 2 SO 4 mixture leads to polishing of the LiTaO 3 substrate surfaces.
- exposure of LiTaO 3 to 100 percent of 97 weight percent aqueous H 2 SO 4 does not lead to etching thereof (within experimental error) at 90° C. even after 40 hours of exposure thereto.
- 149 slices (AT cut) comprising LiTaO 3 were ground to a 12 ⁇ finish.
- the samples were then immersed at 90° C., in an etching solution comprising 65 volume percent of an aqueous 49 weight percent HF solution and 35 volume percent of an aqueous 97 weight percent H 2 SO 4 solution.
- the samples were maintained in the etching solution for two hours to etch the surfaces thereof, i.e., to remove surface blemishes, damages and irregularities. After about two hours and a removal of 24 microns from the surfaces thereof, the samples were removed from the etchant solution and water rinsed.
- polishing a LiTaO 3 substrate are as follows:
- a lithium tantalate (LiTaO 3 ) slice (AT cut) was ground to a 12 ⁇ finish. The slice was then immersed at 90° C. for 30 minutes, in an aqueous mixture comprising 65 volume percent HF (49 weight percent) and 35 volume percent H 2 SO 4 (97 weight percent). The thus treated slice was rendered semi-opaque thereby enabling optical examination by conventional apparatus and means for gross defects therein.
- LiTaO 3 lithium tantalate
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- ing And Chemical Polishing (AREA)
Abstract
A method of etching a surface of a substrate comprising lithium tantalate (LiTaO3) and chemically similar materials is disclosed. The method includes contacting the surface with a mixture comprising hydrofluoric acid and sulfuric acid. In addition to its etching action, the mixture is also capable of polishing the thus treated surface.
Description
1. Field of the Invention
This invention relates to a method of etching a surface of a substrate comprising LiTaO3 and chemically similar materials and more particularly, to a method of etching LiTaO3 with a mixture comprising hydrofluoric acid and sulfuric acid.
2. Description of the Prior Art
Recently, lithium tantalate (LiTaO3) has become of great interest in the electrical device industry. An inherent problem in the use of LiTaO3 has been the etching and polishing of this material. Lithium tantalate (LiTaO3) can be etched with an aqueous mixture consisting of HNO3 and HF. However, the etching can only be carried out at a reasonable rate at the boiling temperature of the mixture. With respect to the polishing of LiTaO3, the HNO3 -HF mixture does not polish a surface of LiTAO3 so that optical inspection thereof for surface and interior defects is possible. An etchant which both etches the LiTaO3 and polishes a surface thereof at a reasonable rate at a moderate temperature is therefore desirable and a method of employing such an etchant is an object of this invention.
The present invention is directed to a method of etching a surface of a substrate comprising LiTaO3 and chemically similar materials and more particularly, to a method of etching LiTaO3 with a mixture comprising hydrofluoric acid and sulfuric acid.
Briefly, the method comprises contacting a surface of a substrate, comprising lithium tantalate (LiTaO3) with a mixture comprising hydrofluoric acid and sulfuric acid whereby etching thereof occurs. Additionally, the mixture has a polishing effect on the etched surface.
The present invention is based upon the discovery of a unique chemical system for etching lithium tantalate and chemically similar compounds such as lithium niobate (LiNbO3) and barium titanate.
The etching system comprises a mixture comprising hydrofluoric acid, HF and sulfuric acid, H2 SO4, contained in at least one suitable liquid solvent carrier. The solvent carrier may be either an aqueous or nonaqueous liquid. A preferred carrier solvent is water.
The concentrations of the respective components, HF and H2 SO4, employed depend on the rate of etch desired at a particular temperature. In this regard, it is to be noted that a preferred mixture concentration for 49 weight percent aqueous HF and 97 weight percent aqueous H2 SO4 typically ranges from about 0.40 to about 0.90 volume fraction of 49 weight percent aqueous HF (about 42.172 moles of HF/1000 gms. H2 O, 40.173 moles of H2 SO4 /1000 gms. H2 O to about 47.535 moles/1000 gms. H2 O and 3.354 moles/1000 gms. H2 O, respectively).
A substrate to be treated, i.e., comprising LiTaO3, is immersed in or exposed in some conventional manner to the etching solution mixture wherein the LiTaO3 is etched. The temperature of the etching solution is maintained at a temperature between room temperature to the boiling point of the particular mixture employed. In this regard, the temperature selected depends upon the parameters such as the etching mixture employed and the etch rate desired. After the substrate has been immersed in the etching solution mixture for the requisite period of time, it is removed therefrom and rinsed with a suitable solvent, e.g., water, and then dried. It is to be noted that exposure to the HF-H2 SO4 mixture leads to polishing of the LiTaO3 substrate surfaces. It is also to be noted that exposure of LiTaO3 to 100 percent of 97 weight percent aqueous H2 SO4 does not lead to etching thereof (within experimental error) at 90° C. even after 40 hours of exposure thereto.
Specific examples of the etching of a LiTaO3 substrate are as follows:
149 slices (AT cut) comprising LiTaO3 were ground to a 12μ finish. The samples were then immersed at 90° C., in an etching solution comprising 65 volume percent of an aqueous 49 weight percent HF solution and 35 volume percent of an aqueous 97 weight percent H2 SO4 solution. The samples were maintained in the etching solution for two hours to etch the surfaces thereof, i.e., to remove surface blemishes, damages and irregularities. After about two hours and a removal of 24 microns from the surfaces thereof, the samples were removed from the etchant solution and water rinsed.
Different samples from among the 149 etched slices were then subjected to varying volume fractions of aqueous 49 weight percent HF and aqueous 97 weight percent H2 SO4 solutions at varying temperatures and time intervals. An etching rate for each sample was then determined by measuring the weight change thereof and the area of each sample, using standard techniques and equipment. The rate was then calculated from this data and the density of LiTaO3 [ 7.454 g/cm3 as reported by R. T. Smith, Applied Physics Letters, 11, 1461 (1967)] using a conventional procedure. The various experimental rates are given in Tables I to VI.
TABLE I ______________________________________ (Temperature = 25° C) Volume Molality of Molality of Etching Fraction HF (moles/ H.sub.2 SO.sub.4 (moles/ Rate of HF 1000 g. H.sub.2 O) 1000 g. H.sub.2 O) (μm/hr.) ______________________________________ 0.00 0.000 329.684 -- 0.10 26.206 149.783 -- 0.20 35.053 89.045 0.60939 0.30 39.498 58.530 0.04695 0.30 39.498 58.530 0.04695 0.35 40.983 48.336 0.09793 0.35 40.983 48.336 0.08854 0.40 42.172 40.173 0.12074 0.40 42.172 40.173 0.11672 0.45 43.146 33.490 0.17440 0.45 43.146 33.490 0.16099 0.47 43.487 31.143 0.18782 0.47 43.487 31.143 0.17843 0.50 43.957 27.916 0.21063 0.50 43.957 27.916 0.23746 0.60 45.234 19.151 0.21465 0.60 45.234 19.151 0.23880 0.65 45.745 15.643 0.23343 0.65 45.745 15.643 0.22807 0.70 46.192 12.572 0.22404 0.70 46.192 12.572 0.22672 0.75 46.587 9.862 0.20123 0.75 46.587 9.862 0.19050 0.80 46.938 7.452 0.17440 0.80 46.938 7.452 0.16904 0.90 47.535 3.354 0.10732 0.90 47.535 3.354 0.10598 1.00 48.024 0.000 0.05098 1.00 48.024 0.000 0.03354 ______________________________________
TABLE II ______________________________________ (Temperature = 38° C) Volume Fraction Etching Rate of HF (μm/hr.) ______________________________________ 0.00 0.00671 0.00 0.00939 0.10 0.00671 0.10 0.00402 0.20 0.02817 0.20 0.03354 0.30 0.07915 0.30 0.13684 0.35 0.20123 0.35 0.19318 0.40 0.26831 0.40 0.29514 0.45 0.30856 0.45 0.37027 0.47 0.45345 0.47 0.40783 0.50 0.46150 0.60 0.59968 0.65 0.56346 0.70 0.59029 0.75 0.55004 0.75 0.51382 0.80 0.46955 0.80 0.34478 0.90 0.23343 1.00 0.18782 1.00 0.13818 ______________________________________
TABLE III ______________________________________ (Temperature = 51° C) Volume Fraction Etching Rate of HF (μm/hr.) ______________________________________ 0.00 0.05366 0.10 0.02683 0.20 0.03622 0.30 0.36893 0.30 0.43467 0.35 0.40247 0.40 0.80494 0.40 0.81030 0.45 0.93104 0.47 1.01556 0.60 1.34156 0.60 1.51731 0.65 1.32815 0.65 1.51596 0.70 1.22082 0.75 1.37778 0.75 1.30131 0.80 1.03300 0.80 1.28253 0.90 0.63053 0.90 0.72713 1.00 0.42930 1.00 0.39710 ______________________________________
TABLE IV ______________________________________ (Temperature = 64° C) Volume Fraction Etching Rate of HF (μm/hr.) ______________________________________ 0.00 0.07379 0.00 0.07513 0.10 0.02415 0.10 0.02146 0.20 0.13416 0.40 2.14650 0.45 2.16796 0.47 2.54897 0.47 2.62275 0.47 2.19479 0.50 2.03917 0.60 2.95144 0.65 3.48806 0.70 3.21975 0.75 2.95144 0.80 2.68312 0.90 1.87819 0.90 1.41266 1.00 0.83311 ______________________________________
TABLE V ______________________________________ (Temperature = 77° C) Volume Fraction Etching Rate of HF (μm/hr.) ______________________________________ 0.00 0.22807 0.10 0.04025 0.10 0.02281 0.20 0.18782 0.20 0.24551 0.30 1.51731 0.35 1.91441 0.40 3.08559 0.40 3.33110 0.45 3.78052 0.47 4.31580 0.50 4.65790 0.60 6.43950 0.60 6.30400 0.65 6.03703 0.65 6.17655 0.70 5.98336 0.70 6.28522 0.75 5.76871 0.75 4.77998 0.80 5.90287 0.90 4.42715 0.90 3.74966 1.00 1.74403 1.00 1.72122 ______________________________________
TABLE VI ______________________________________ (Temperature = 90° C) Volume Fraction Etching Rate of HF (μm/hr.) ______________________________________ 0.0 0.09659 0.20 0.60370 0.20 0.35149 0.30 1.74403 0.30 1.80977 0.35 2.95144 0.35 3.28817 0.40 3.89053 0.40 5.57553 0.45 7.78106 0.45 6.89697 0.47 7.07003 0.50 8.98846 0.50 8.65576 0.60 11.40327 0.60 9.45667 0.65 12.20821 0.65 10.82506 0.70 11.13496 0.70 10.05500 0.75 11.40327 0.75 10.19453 0.80 10.46418 0.90 7.51274 0.90 7.34773 1.00 4.42715 1.00 5.08452 1.00 4.25007 ______________________________________
Specific examples of polishing a LiTaO3 substrate are as follows:
1. A lithium tantalate (LiTaO3) slice (AT cut) was ground to a 12μ finish. The slice was then immersed at 90° C. for 30 minutes, in an aqueous mixture comprising 65 volume percent HF (49 weight percent) and 35 volume percent H2 SO4 (97 weight percent). The thus treated slice was rendered semi-opaque thereby enabling optical examination by conventional apparatus and means for gross defects therein.
2. The procedure of (1) above was repeated except that the slice was immersed in the mixture for four hours. The slice was rendered almost transparent as well as having the surfaces thereof polished.
Claims (4)
1. A method of etching a surface of a substrate comprising LiTaO3, which comprises contacting the surface with a mixture comprising HF present in an amount ranging from about 42.172 to about 47.535 molal and H2 SO4 present in an amount ranging from about 40.173 to about 3.354 molal.
2. A method of treating a body comprising lithium tantalate to obtain a polished surface thereof, which comprises contacting the surface with a mixture comprising HF present in an amount ranging from about 42.172 to about 47.535 molal and H2 SO4 present in an amount ranging from about 40.173 to about 3.354 molal.
3. A method of optically examining a substrate comprising LiTaO3 which comprises treating the substrate with a mixture comprising HF present in an amount ranging from about 42.172 molal to about 47.535 molal and H2 SO4 present in an amount ranging from about 40.173 to about 3.354 molal.
4. The method as defined in claim 3 which further comprises directly examining said treated substrate with optical means. .Iadd. 5. A method of etching a surface of a substrate comprising lithium tantalate, which comprises contacting the surface with a mixture comprising HF and H2 SO4. .Iaddend. .Iadd. 6. A method of treating a body comprising lithium tantalate to obtain a polished surface thereof, which comprises contacting the surface with a mixture comprising HF and H2 SO4. .Iaddend. .Iadd. 7. A method of etching a surface of a substrate comprising lithium niobate, which comprises contacting the surface with a mixture comprising HF and H2 SO4..Iaddend.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US05/751,926 USRE29336E (en) | 1974-02-22 | 1976-12-17 | Method of etching a surface of a substrate comprising LiTaO3 and chemically similar materials |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US445039A US3860467A (en) | 1974-02-22 | 1974-02-22 | Method of etching a surface of a substrate comprising LITAO{HD 3 {B and chemically similar materials |
US05/751,926 USRE29336E (en) | 1974-02-22 | 1976-12-17 | Method of etching a surface of a substrate comprising LiTaO3 and chemically similar materials |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US445039A Reissue US3860467A (en) | 1974-02-22 | 1974-02-22 | Method of etching a surface of a substrate comprising LITAO{HD 3 {B and chemically similar materials |
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USRE29336E true USRE29336E (en) | 1977-08-02 |
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US05/751,926 Expired - Lifetime USRE29336E (en) | 1974-02-22 | 1976-12-17 | Method of etching a surface of a substrate comprising LiTaO3 and chemically similar materials |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6270688B1 (en) * | 1994-04-07 | 2001-08-07 | Raytheon Company | Chemical polishing of barium strontium titanate |
US20190275565A1 (en) * | 2018-03-06 | 2019-09-12 | GM Global Technology Operations LLC | Method of selectively removing a contaminant from an optical component |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1777321A (en) * | 1928-09-24 | 1930-10-07 | Meth Isaac | Glass-polishing solution and method of polishing glass |
US2847287A (en) * | 1956-07-20 | 1958-08-12 | Bell Telephone Labor Inc | Etching processes and solutions |
US3546037A (en) * | 1965-05-26 | 1970-12-08 | Saelzle Erich | Polishing crystal glass |
-
1976
- 1976-12-17 US US05/751,926 patent/USRE29336E/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1777321A (en) * | 1928-09-24 | 1930-10-07 | Meth Isaac | Glass-polishing solution and method of polishing glass |
US2847287A (en) * | 1956-07-20 | 1958-08-12 | Bell Telephone Labor Inc | Etching processes and solutions |
US3546037A (en) * | 1965-05-26 | 1970-12-08 | Saelzle Erich | Polishing crystal glass |
Non-Patent Citations (3)
Title |
---|
Applied Physics Letters, vol. 6, No. 11, 6-1-1965, by K. Nassau et al., pp. 228 and 229, (Etching of LiNbO.sub.3). * |
Applied Physics Letters, vol. 6, No. 11, 6-1-1965, by K. Nassau et al., pp. 228 and 229, (Etching of LiNbO3). |
Journal of Applied Physics, Domain Structure and Curie Temperature of Single-Crystal Lithium Tantalate by H. J. Levinstein et al., 6-22-1966, pp. 4585 and 4586. * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6270688B1 (en) * | 1994-04-07 | 2001-08-07 | Raytheon Company | Chemical polishing of barium strontium titanate |
US20190275565A1 (en) * | 2018-03-06 | 2019-09-12 | GM Global Technology Operations LLC | Method of selectively removing a contaminant from an optical component |
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