Yoichi Shinba

Fine-pitch hybrid bonding with Cu/Sn microbumps and adhesive for high density 3D integration

In this study, we developed single-pitch hybrid bonding technology for high density 3D integration. To realize the single-pitch, smaller than 10-μm pitch, hybrid bonding, 8 μm-pitch Cu/Sn microbumps and nonconductive film (NCF) were used. The planar structure to simultaneously bond was formed by chemical mechanical polishing (CMP). After the planarization, the Cu/Sn bumps and NCF were simultaneously bonded at 250 °C for 60 s. Cross sectional observation of the bonded sample by scanning electron microscope (SEM) indicated that 8 μm-pitch bump bonding was carried out successfully and the NCF filled the 2.5-μm gap between the chip and substrate without significant voids. In addition, a tensile test was performed as a mechanical reliability test. The tensile strength was 3.86 MPa. From SEM observation of the fractured surface after the tensile test, the fractured surface of the bumps was intermetallic compound (IMC) layer between Cu and Sn. These results indicated that hybrid bonding was effective method for single-pitch bonding and underfilling.

Development of thermal conductive sheet with low interfacial heat resistance

Abstract In order to reduce total heat resistance, we focused on reducing an interfacial heat resistance between high thermal conductive sheet composed of resin and heat conductive filler and metal such as Cu or Al. The interfacial heat resistance was determined by dispersion of high heat conductive filler and interfacial residual stress. The good dispersed sheet shows lower interfacial resistance than poor dispersed sheet, The interfacial residual stress causes an poor contact to metal to make void in the interface. To consider the effect of those facts, we successfully developed the high thermal conductive sheet with extremely low interfacial resistance. The interface heat resistance is below 0,009W/C.

Fine-pitch interconnection by hybrid Cu/Sn-adhesive bonding for 3D integration

In this study, we developed 8 μm-pitch microbump bonding and encapsulating by hybrid Cu/Sn-adhesive bonding technology. As an adhesive material, we used a non-conductive film (NCF). To realize simultaneous bonding of a metal and an adhesive, planar structure was formed by chemical mechanical polishing (CMP). After the planarization, hybrid bonding was carried out at 250 °C for 60 s. From scanning electron microscopic (SEM) observation of the bonded sample, it was confirmed that 8 μm-pitch bump bonding and the NCF filling 2.5-μm gap between the chip and substrate were performed at the same time. This result indicated that hybrid bonding was effective in fine-pitch bonding and encapsulating for future three-dimensional (3D) integration.