The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 24, 1995
Filed:
May. 20, 1994
Monte A Douglas, Coppell, TX (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
An anisotropic liquid phase photochemical etch is performed by submersing a substrate 30 (e.g. copper) in a liquid 34 containing an etchant (e.g. hydrochloric acid) and a passivant (e.g. iodine), the passivant forming an insoluble passivation layer 36 (e.g. Cul) on the surface, preventing the etchant from etching the surface. The passivant and its concentration are chosen such that the passivation layer 36 has a solubility which is substantially increased when it is illuminated with radiation 38 (e.g. visible/ultraviolet light). Portions of the surface are then illuminated with radiation 38, whereby the passivation layer 36 is removed from those illuminated portions of the surface, allowing the etch to proceed there. Portions of the surface not illuminated are not etched, resulting in an anisotropic etch. Preferably, an etch mask 32 is used to create the unilluminated areas. This etch mask 32 may be formed on the surface or it may be interposed between the surface and the radiation source.