| 摘要 |
1,182,422. Etching. PLESSEY CO. Ltd. 9 June, 1967 [15 June, 1966; 1 March, 1967], Nos. 26666/66 and 9772/67. Heading B6J. [Also in Division H1] Different metals in a multi-layer structure are etched by applying a positive working photo-resist to the outer layer of metal; exposing a first pattern and developing to remove the exposed resist; exposing a second pattern in the remaining resist; etching the outer layer of metal under the exposed first pattern; and then at some stage after this first etching step, developing the second pattern is permit the outer layer of metal under the exposed second pattern to be etched. In an example, successive layers (5, 6, 7) (Fig. 3, not shown) of aluminium nickel and aluminium are deposited on a glass substrate 4 and covered with a positiveworking photo-resist (8). The resist is exposed and developed to leave unexposed resist over areas 1, 2 and 3, Fig. 2, and then a second pattern is formed by exposing resist over area 3 only. The exposed aluminium is etched away with an ammonium persulphate/orthophosphoric acid mixture and then the second pattern is developed (Fig. 6, not shown). The exposed nickel layer is removed with dilute nitric acid (Fig. 7, not shown), and then the persulphate/phosphoric acid mixture is again used to not only remove the lowest layer (5) of exposed aluminium, but also to remove the top layer (6) in area 3. The remaining photo-resist, i.e. on areas 1 and 2, is then removed to leave a three layer metal pad on areas 1 and 2 and a twolayer interconnecting part in area 3. The process is applicable to more than two patterns. |
