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Processability of organic material for semiconductor packaging by 248 nm excimer laser

High performance, high speed processing, and miniaturization of electronic devices are advancing, due to the rapid development of highly advanced information society in recent years. Semiconductors continue to be highly integrated according to Moore's law, and semiconductor package substrates are also required to be miniaturized and highly densified. The build-up method is one of the methods for miniaturization and high density of semiconductor package substrates. The build-up method is method of alternately forming insulation layers and conductor layers on both sides of a glass epoxy substrate. In general, an organic build-up film is used for the insulation layers, and a via is formed in the insulation layers by laser processing. However, the miniaturization of the organic build-up film process by the commonly used 355 nm UV laser has almost reached the limit due to its long wavelength. Therefore, to miniaturize the build-up film process, it is necessary to use excimer laser with shorter wavelength than the UV laser. We are developing the processing of organic build-up film by 248 nm excimer laser with free spectrum operation. The organic build-up films are processed directly by the irradiation using the mask by 248 nm excimer laser. We processed using Ajinomoto build-up films (ABF) as organic material. The type of ABF was GY50. We confirmed that it is possible to process via of 3 μm in build-up film and the DOF can be increased depending on the process conditions. We will report on the processability of build-up film using 248 nm excimer laser.