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:
Jun. 22, 1976
Filed:
Sep. 30, 1974
Robert J Walsh, Ballwin, MO (US);
Monsanto Company, St. Louis, MO (US);
Abstract
Circular wafers of semiconductor (silicon) are chemically treated, e.g., etched, by supporting the wafers vertically by contacting their edges with annularly grooved drive rollers, immersing the supported wafers in a body of chemical medium (e.g., etchant solution) for treatment, and rotating the wafers by rotation of the drive rollers while the wafers are immersed in the body of medium to uniformly and precisely treat the surfaces of the wafers. Apparatus for effecting such precision etching includes an etchant tank, a wafer rack including the drive rollers which support the edges of the wafers in vertical face-to-face relationship, the rack being lowered into the etchant to immerse the wafers. Means is disclosed for rotating the drive rollers for rotation of the immersed wafers and provision is included for circulating the etchant for causing uniform flow thereof past the rotating wafers. A heat exchanger maintains the etchant substantially at a predetermined temperature.