| 摘要 |
1416633 Integrated circuits HUGHES AIRCRAFT CO 17 July 1973 [17 July 1972] 33927/73 Heading H1K Batch production of complex logic circuits from a semiconductor wafer containing a number of basic logic circuit cells provided with terminal connection pads involves depositing a first layer of insulation leaving the pads exposed, and a first level of metallization interconnecting the cells into groups, testing the cells and mapping the properly functioning ones, depositing a second layer of insulation exposing contact pads of these and a second level of metallization relocating these pads to standard positions. The components of the basic cells may be formed by diffusion in junction isolated regions of an eptaxial layer over buried regions and interconnected by aluminium metallization or silica passivation. The terminal pads of the cells are then covered with mushrooms of aluminium-coated magnesium, glass deposited overall by sputtering and the mushrooms removed to leave tapered holes in the glass. A layer of aluminium is deposited overall and etched to interconnect the cells to form complex circuits. After testing and mapping properly functioning circuits a further apertured layer of glass is provided as above and another layer of aluminium deposited and etched via a mask to relocate the terminal pads of the circuits in standard positions on the wafer. Faults arising from etching of the lowermost aluminium via pinholes in the glass by the etchant used to patten the next aluminium layer are largely avoided if, prior to depositing that next layer, layers of magnesium and aluminium are deposited, the aluminium etched via a reversal mask, and the thus exposed magnesium removed with a selective etch with a degree of undercutting. The aluminium layer is then deposited and patterned by removal of the remaining magnesium and hence the aluminium overlying it. |
