| 摘要 |
1,188,507. Anodizing semi-conductors. WESTERN ELECTRIC CO. Inc. April 18, 1967 [May 11, 1966], No.17721/67. Heading C7B. [Also in Division H1] . A mask is formed on a semi-conductor body e. g. a silicon wafer by forming first and second dielectric films on a face of the body, the first film e. g. of silicon oxide or organic photo-resist forming a mask pattern and the second film e.g. of silicon nitride or aluminium oxide or silicate or SiC being co-extensive with the face, anodizing the films so that portions of the second film not contiguous with the first have their solubility changed the first being of sufficient thickness to withstand anodizing, and etching away portions of altered solubility e.g. in buffered HF solution. The first film may be in contact with the face, the second film overlying the first and unmasked portions of that face; or the second film may be in contact with the face, the first film overlying portions of the second. A silicon nitride film may be anodized in an electrolyte solution of pyrophosphoric acid or KNO 2 in tetrahydrofurfuryl alcohol, and a crystalline aluminum oxide film in an ammonium pentaborate solution. The semiconductor body itself may isolate the electrolyte into catholyte and anolyte in which are immersed Pt electrodes. The D.C. voltage may be allowed to rise to a predetermined value while passing a constant current, or a constant voltage may be applied and the current allowed to decay. |
