Electronic Packaging and Interconnection: Advanced Microelectronic Packaging Materials
Sponsored by: TMS Functional Materials Division, TMS: Electronic Packaging and Interconnection Materials Committee
Program Organizers: Kazuhiro Nogita, University of Queensland; Mohd Arif Mohd Salleh, Universiti Malaysia Perlis; Dan Li, Beijing University of Technology; David Yan, San Jose State University; Fan-Yi Ouyang, National Tsing Hua University; Patrick Shamberger, Texas A&M University; Tae-Kyu Lee, Cisco Systems; Christopher Gourlay, Imperial College London; Albert T. Wu, National Central University

Wednesday 2:00 PM
March 22, 2023
Room: Sapphire E
Location: Hilton

Session Chair: David Yan, San Jose State University; Tae-Kyu Lee, Cisco Systems


2:00 PM Introductory Comments

2:05 PM  Invited
Effects of Diameter on Copper Pillar with Solder Cap Interconnections during Reflow Soldering Process: Lee Jing Rou1; Mohd Sharizal Abdul Aziz1; Mohd Arif Anuar Mohd Salleh2; Khor Chu Yee3; Mohammad Hafifi Hafiz Ishak4; 1School of Mechanical Engineering, Universiti Sains Malaysia; 2Center of Excellence Geopolymer & Green Technology (CeGeoGTech), Universiti Malaysia Perlis; 3Faculty of Mechanical Engineering Technology, Universiti Malaysia Perlis; 4School of Aerospace Engineering, Universiti Sains Malaysia
    Recently, the copper pillar with solder cap interconnection has been introduced as an alternative for the solder bump interconnection in order to tackle the limitations, such as the collapsing nature of the solder bump and larger pitch size. This paper presents an effective simulation tool to evaluate the effects of different diameters of the copper pillar with solder cap during the reflow soldering process. A three-dimensional numerical approach is used to investigate the thermal behaviour of the copper pillar with solder cap with different diameters. The interconnection bump diameters are 150, 200, 250, 300 and 350μm. The model is developed and meshed using the Computational Fluid Dynamics (CFD) software. The temperature distributions of the copper pillar with solder cap with different diameters are predicted. The paper aims to provide an understanding of the effect of diameters on the temperature distribution of copper pillars with solder cap during reflow soldering.

2:30 PM  
Current-enhanced Presureless Sintering of Cu Nanoparticles at Room Temperature: Tzu-Hao Shen1; Albert T. Wu1; 1National Central University
    Low-temperature sintering of Cu nanoparticles is an attractive approach to realize joint in devices for high-temperature applications. This study presents a low current-enhanced sintering method for Cu nanoparticles without applying pressure at low temperature. Commercial Cu nanoparticles with an average diameter of 300 nm were mixed with polyethylene glycol (PEG) as Cu paste, which was then filled in V-grooves on Si substrate. After pre-sintered the Cu paste at low temperature, a low current density was applied to further densified the Cu nanoparticles. The effect of the current on the sintering of Cu nanoparticles was investigated. Mathematical models are proposed to discuss the kinetics of growth of the particle necks. The model suggested that along with the curvature-driven ripening, current crowding contribute an additional driving force for sintering.

2:50 PM  
In-situ Observation of the Ga and Cu/Cu6Ni Reaction by Synchrotron Microradiography: Qichao Hao1; Xin Fu Tan1; Shiqian Liu2; Stuart McDonald1; Hideyuki Yasuda3; Kazuhiro Nogita1; 1The University of Queensland; 2The University of Queensland;Shenzhen Technology University; 3Kyoto University
    Gallium (Ga) and Ga-based alloys have attracted attention in the microelectronic packaging industry due to their low melting points. However, the intermetallic compounds (IMC) grow slowly between Ga and Cu-based substrates hindering some practical applications of these alloys. The reaction between Ga and Cu-based substrates is essential for understanding the mechanism of the IMCs formation. In this study, the reaction between the liquid Ga and Cu/Cu-6wt%Ni substrates during heating and cooling processes was investigated by in-situ synchrotron 2D imaging. Comparing the in-situ results with the ex-situ experiments, the influence of the heating temperature and cooling process on the IMCs formation was studied, and the IMCs formed during each stage were investigated to identify the properties such as growth speed, morphology, grain sizes, and preferred grain orientation. The growth kinetics of CuGa2 are different during the heating and cooling processes, and this paper provides new insight into the IMC formation mechanisms.

3:10 PM  
No-Flow Electroless Connections for Die-to-Wafer Attach: Jeng-Hau Huang1; Po-Shao Shih2; Vengudusamy Renganathan1; Simon Gräfner1; Chang-Hsien Shen1; Yu-Chun Lin1; Po-Yu Kung1; C. Robert Kao1; 1National taiwan university; 2National Taiwan University
    Hybrid bonding is considered the most promising technology to realize high interconnection density in 3D packaging. Nevertheless, some challenges such as high temperature and extremely low surface roughness need to be concerned. To solve the following problems, a novel, simple 3D packaging process is developed. Adding a small amount of the high copper concentration electroless Cu plating solution, high uniformity electroless interconnections are achieved in several minutes with very low temperature and no pressure. This process has great potential to apply to micro and nanoscale technology. Owing to its simplicity, it can be expected to use in the wafer-to-wafer level package in the future.

3:30 PM Break

3:50 PM  
Influences of Deposition Speed on Void Formation in Electroless Copper Plating Film for Micro-vias: Ming Chun Hsieh1; Zheng Zhang1; Masahiko Nishijima1; Chuantong Chen1; Katsuaki Suganuma1; Hidekazu Honma2; Yu Shimizu2; Koji Kita2; Joonhaeng Kang2; Takashi Matsunami2; Kuniaki Otsuka2; 1SANKEN, Osaka University; 2Okuno Chemical Industries Co., Ltd
    Micro-via, that connects electrical components to each other, is essential in electrical devices. However, together with the decrease in its size, which has become one-tenth to what it was in late 20th century, nowadays micro-via faces quality problems as delamination and cracks, and “weak micro-via” issue raises high concerns. One of the reasons that causes weak micro-via problem is formation of nano- to micro-sized voids in electroless plating layer in micro-via structure. However, mechanism of void formation is not sufficiently studied yet. In order to identify the reason(s) that is related to void formation, we investigated the influence of Cu deposition speed on void formation in electroless Cu plating layer for micro-vias by adjust deposition speed to 3 different rates. Electroless plating Cu layer deposited with the 3 different deposition speeds are observed by FE-SEM and TEM and their morphological and numerical differences of voids will be discussed.

4:10 PM  
Phase-field Simulation of Deposition Profile and Microstructure of Thin Film on Nonplanar Substrate: Hwanwook Lee1; Ahmad Nadeem1; Kiran Raj1; Yongwoo Kwon1; 1Hongik University
    Almost all current nano-devices, such as gate-all-around(GAA)-FETs, DRAM, and 3D NAND, require high aspect ratio(HAR). In all these cases, the deposition profile and microstructure of thin films should be well controlled. Polycrystalline structures are difficult to be dealt with atomic-scale simulations due to the large number of atoms and long-time scale. On the other hand, the topological changes of grain boundaries cannot be dealt with by continuum-scale TCAD process simulation. Therefore, a mesoscale simulation, phase-field method (PFM) is the right choice. In this presentation, we will present our development status of phase-field model for a vapor-film-substrate system that can simulate the deposition profile and microstructure on nanostructures, along with nanoscale size effects.

4:30 PM  
Network Structure and Viscoelasticity of Flexible Electronic Interconnects based on Linear Low-density Polyethylene (LLDPE) and Liquid Silicone Rubber (LSR) Conductive Polymer Composites: Khairul Anwar Abdul Halim1; Mohd Arif Anuar Mohd Salleh1; Mohd. Firdaus Omar1; Azlin Fazlina Osman1; Muhammad Salihin Zakaria1; 1Faculty of Chemical Engineering Technology, Universiti Malaysia Perlis
    Flexible conductive polymer composites (CPCs) had become area of interest as electronic interconnect. The ability of a polymer matrix to conduct electric depends upon the conductive filler concentrations and formation of network path. Furthermore, interconnects are deemed to have the ability to maintain high conductivity whilst flexible following the movement of the electronic device at various operating temperature and conditions. The main aim of this research works was to establish and understand the correlation between the network structure and viscoelastic properties of a linear low-density polyethylene (LLDPE) and liquid silicone rubber (LSR) compounded with various conductive fillers. The resulting CPC samples were characterized and tested using various techniques such as synchrotron micro-X-Ray Fluorescence (XRF) technique, electron microscopy, dynamic mechanical analysis, thermal studies, 4-point probe, and tensile testing. The data obtained revealed the potential of utilizing CPCs as flexible interconnects suitable for advance electronic applications.

4:50 PM  
On the Thermal Aging of the Nanoporous Structure of Sintered Ag on a Cu Substrate: Xavier Milhet1; Jerome Colin1; Azdine Nait-Ali1; Kokouvi N'Tsouaglo1; Loic Signor1; 1Pprime Institute Cnrs Ensma
    As power modules are a complex assembly of different materials a fine evaluation of the evolution of the materials and interfaces is necessary during aging. In this work, time resolved evolution (4D) of the nanoporous microstructure of sintered Ag (s-Ag) and sintered Ag on Cu (s-Ag/Cu) during thermal aging was monitored at high temperature using in-situ X-ray nanotomography. For both types of specimen, the density remains constant, the evolution is driven by the bigger pores and the pore growth follows the Ostwald ripening mechanism leading to a decrease of the smaller pore number. Faster kinetics of growth is observed for s-Ag/Cu before deviating from Ostwald ripening after a critical time. Furthermore, complex evolutions in small pores clusters can be observed in both type of specimens. Those behaviors are discussed based on diffusion mechanisms in relation with a competition between local stresses relaxation and surface energy during diffusion.

5:10 PM Concluding Comments