Method for anisotropic etching of structures in conducting materials
First Claim
1. A method for anisotropic etching of a structure in an electrically conductive substance by means of an etchant which in a first solution at a first concentration and in the absence of an electric field will isotropically etch structures in the substance by spontaneous chemical reaction with the substance, said method comprising the steps of:
- contacting the substance with a second solution of the etchant which is diluted to a second concentration lower than said first concentration and which will isotropically etch structures in the substance by spontaneous chemical reaction with the substance in the absence of an electric field at a maximum etching rate of 5 nm/s; and
subjecting the second solution adjacent to the area of the substance to be etched to an electric field of such a strength that anisotropic etching of said structure in the substance is accomplished.
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Abstract
In a method for anisotropic etching of a structure in an electrically conductive substance to be etched, use is made of an etchant which in concentrated solution is usable for isotopic etching of structures in the substance to be etched. The substance to be etched is contacted with the etchant in a solution which is so diluted that the etchant is unusable for isotropic etching. The etchant is subjected, adjacent to the substance to be etched, to an electric field of such a strength that anisotropic etching of the substance to be etched is accomplished. Moreover, an etching fluid is described, comprising an etchant in dilute solution, in which the etchant is present in a concentration of 200 mM at most, and use of such an etching fluid for making structures which are 50 μm or less is also described.
56 Citations
23 Claims
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1. A method for anisotropic etching of a structure in an electrically conductive substance by means of an etchant which in a first solution at a first concentration and in the absence of an electric field will isotropically etch structures in the substance by spontaneous chemical reaction with the substance, said method comprising the steps of:
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contacting the substance with a second solution of the etchant which is diluted to a second concentration lower than said first concentration and which will isotropically etch structures in the substance by spontaneous chemical reaction with the substance in the absence of an electric field at a maximum etching rate of 5 nm/s; and
subjecting the second solution adjacent to the area of the substance to be etched to an electric field of such a strength that anisotropic etching of said structure in the substance is accomplished. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification