Plasma treatment methods to improve indium bump bonding via indium oxide removal

摘要

Flip chip hybridization, also known as bump bonding, is a packaging technique for microelectronic devices which directly connects an active element or a detector to a substrate readout face down, eliminating the need for wire bonding. Indium bump technology has been a part of hybridization for many years and has been extensively employed in the infrared imager industry. However, obtaining a reliable, high yield process for high density patterns of bumps can be quite difficult in part due to the tendency of the indium bumps to oxidize during exposure to air. In this study, plasma, thermal, and wet chemical methods were screened to determine their ability to remove indium oxide from indium bumps. A novel two-step plasma process using methane, argon, and hydrogen was developed that removes indium oxide from indium bumps after prolonged air exposure while maintaining a low sample temperature. This method was tested by fabricating a fully hybridized scientific grade visible complementary metal oxide semiconductor detector and imaging a standard test pattern.