High density and reliable packaging technology with Non Conductive Film for 3D/TSV

Abstract

The innovative flip chip assembly process with Non Conductive Film (NCF) contributes to high density and reliable 3D/TSV integrations has been developed and demonstrated. The target package had two tier structure which consisted of a logic device and Wide I/O DRAM. The logic device was fabricated by via-middle process and accompanied with 1200 TSVs, a thickness of 50 μm and 40 μm / 50 μm bump pitch layout. Thermalcompression bonding method with Cu pillar was applied to both connections between the memory die and the logic die and between the logic die and an organic substrate so that the high reliability could be achieved. In this work, NCF laminated on substrates was selected as an underfill material to establish robust process for 3D integrations and to realize the cost effective assembly. As reliability test items, 1500-cycle temperature cycling test, 1000h high temperature storage test, 1000h high humidity test, 500h unbiased highly accelerated stress test and 300h pressure cooker test were performed. Furthermore, 28 nm logic device and Wide I/O DRAM were assembled into the 3D structure with this new technology and 12.8 GB/s transmission and 89 % reduction of I/O power compared to LPDDR3 were demonstrated.

Challenges of design and packaging for 3D stacking with logic and DRAM dies

“…PACKAGING TECHNOLOGY [7,10] The selection of the material for underfill resin is one of the keys in 3D packaging. Widely used pre-applied underfill materials such as Non-Conductive Paste (NCP) and Capillary Underfill (CUF) has some risks of underfill creep or voids as shown in Fig 10. From our experience, Non-Conductive Film (NCF) on substrate is chosen for void-free underfill formation.…”

Implementation of Flip-Chip Microbump Bonding between InP and SiC Substrates for Millimeter-Wave Applications

“…On the other hand, μ-bump bonding consisting of electro-plated copper (Cu) pillar bumps and solder bonding [ 13 , 14 ] is a mature process technology that has been used in commercial 3D stacking memory products [ 14 , 15 ], and thereby it can be introduced to implement mmW 3D MICs and transceiver systems reproducibly. With the improvement of the alignment accuracy of bonding equipment, it is possible to densely form μ-bumps with a diameter (or width) of only a few to a few tens of micrometers [ 14 , 16 ]. Recently, heterogeneous μ-bump bonding technologies concerning various substrates, such as InP-to-SiC [ 5 ], InP-to-Si [ 17 ], and AlN/diamond-to-Si [ 18 ], have been reported for utilization in mmW wireless communication applications.…”