A study on the interconnection properties of 3D TSV chip using non-conductive films(NCFs) with thermal acid generator(TAG)

Abstract

Much research has been made for the TSV(Through Silicon Via) technology to be realized in the 3D chip stacking technology. A vertical chip interconnection method using Cu/SnAg bumps and NCFs(non-conductive films) has been gaining a lot of interest as one of the most promising ways for 3D TSV vertical interconnection. In this thesis, the effects of NCF on the joint interconnection of TSV chips to compensate the role of flux and under-fill were investigated. NCF contains thermal acid generator (TAG) to remove the solder ox-ide layer. The effects of TAG on the stable joint interconnection were studied. The relation between the viscosity of pre-applied NCFs and loading forces was investigated to predict the gap change between a TSV chip and a substrate chip. The existing theories of squeezing flow are adapted to predict the gap change of a real TSV chip and a substrate chip during TSV bonding using a simplified model. Real gap measured by bonding of test dies were matched to check the validity of the prediction model. Through the studies on the material properties of NCFs, the effects of NCF properties on the reliability of assembled chips us-ing NCF were investigated. As a result, not only the properties of NCF with TAG were closely studied in terms of solder oxide removing and flow kinetics, but also the NCF suc-cessfully substitute the flux and underfill for the fine pitch TSV chip interconnection.