| 摘要 |
PURPOSE:To contrive the improvement in throughput by enabling the collective formation of minute wirings. CONSTITUTION:Polyimide 12 fills up the intervals between a chip 2 and a package substrate 11 and its surface is on a level with the chip and substrate so as to make the surface flat. If a copper thin film is vapor-deposited on that, there is not possibility of disconnection due to the unevenness of height so that it is possible to spread a copper film of 1mum to a few mum followed by patterning by photo process. For the etching the copper film, ferric chloride is used. At this time, the package substrate preferably has a thermal expansion coefficient approximate to that of the chip and accordingly a substrate of silicon carbide (SiC) is suitable. In addition, as the SiC substrate also has a good heat conductivity, it is the optimum material. As the chip and the polyimide have the approximate thermal expansion coefficient with each other and also approximate to that of the package substrate, there is no possibility of disconnection of the thin film pattern 13 even if the temperature increases to the high degree during the operation and the reliability of wiring is improved. |
