Thin film transistor films made with anodized film and reverse-anodized etching technique

Abstract

Anodising treatments are used to form insulating films (12) in the manufacture of a flat-panel display or other large-area thin-film electronic device. A first film (1,101) of anodisable material (e.g Al) is anodised through a part of its thickness to form an anodic second film (2). A mask pattern (4), e.g of photoresist, is provided at least on the second film (2) to define an area (5) where the second film (2) is etched away through at least a part of its thickness and where a further anodising step is carried out to form an anodic third film (3) contiguous with a remaining part of the anodic second film (2). The manufacture is simplified by using reverse-anodising in an electrolyte solution (20) to carry out the etching of the second film (2). The first film (1,101) is biased negatively as a cathode to carry out the reverse-anodising, after which the further anodising step is carried out by biasing the first film (1,101) positively as an anode in the same electrolyte solution (20) to form the anodic third film (3). A remaining part (11a, 11b) of the first film (1) may provide a conductor track or gate electrode over which there is an insulating film (12) comprising a part of the anodic second film (2) on top of the track/electrode (11a, 11b) and a part of the anodic third film (3) on a sloping side-wall of the track/electrode (11a, 11b). A crossing track (C2,18) or TFT channel region 15 may be deposited over the insulated track/electrode (11a, 11b).

Dependencies are inferred from the claim text.