| 摘要 |
1305236 Semi-conductor devices INTERNATIONAL BUSINESS MACHINES CORP 16 June 1970 [30 June 1969] 29114/70 Heading H1K Electromigration in and environmental damage to conductive tracks of silver in integrated circuits is reduced by surrounding the tracks with a layer consisting of one or more refractory metals, such as nickel, chromium, tantalum, titanium, molybdenum and tungsten. Typically the tracks extend to platinum silicide contacts located in apertures in a silicon dioxide passivating layer on a silicon wafer. In one preferred embodiment layers of chromium, silver and chromium are vapour deposited overall to thicknesses of 700, 7000 and 500 Š respectively and then etched or back-sputtered using photoresist masking to form conductive tracks but with the lower chromium layer maintained intact. Nickel is then deposited by electroplating, the tracks protected by photoresist, and excess nickel and underlying chromium removed by etching or back-sputtering to leave nickel only on the edges of the silver tracks. In another embodiment, Fig. 6D, the wafer, carrying a Cr-Ag-Cr sandwich track produced as above, is coated by evaporation or sputtering with chromium to a thickness of 1000 Š and the chromium between tracks removed. In yet another case a silver coated chromium track is coated with 200 Š of nickel by electroplating overall followed by back etching of unwanted nickel. Finally in a simpler method the tracks are made by coevaporation of silver and chromium (1-5% by weight) at <200‹ C. followed by patterning. Heating, e.g. for from 10 sees. to 2 hours at 700-500‹ C. causes the chromium, which is in supersaturated solution, to diffuse to the surfaces of the track to form the protective layer. |
