2024

Vol.30 No.4

Editorial Office

Current Issue

Journal of the Microelectronics and Packaging Society 2023;30(4):
A Review on the Bonding Characteristics of SiCN for Low-temperature Cu Hybrid Bonding

Yeonju Kim, Sang Woo Park, Min Seong Jung, Ji Hun Kim, and Jong Kyung Park

Department of Semiconductor Engineering, Seoul National University of Science and Technology, 232, Gongneung-ro, Nowon-gu, Seoul, 01811, Korea

Journal of the Microelectronics and Packaging Society Vol. 30, No. 4, pp. 8-16.

Abstract

The importance of next-generation packaging technologies is being emphasized as a solution as the miniaturization of devices reaches its limits. To address the bottleneck issue, there is an increasing need for 2.5D and 3D interconnect pitches. This aims to minimize signal delays while meeting requirements such as small size, low power consumption, and a high number of I/Os. Hybrid bonding technology is gaining attention as an alternative to conventional solder bumps due to their limitations such as miniaturization constraints and reliability issues in high-temperature processes. Recently, there has been active research conducted on SiCN to address and enhance the limitations of the Cu/ SiO2 structure. This paper introduces the advantages of Cu/SiCN over the Cu/SiO2 structure, taking into account various deposition conditions including precursor, deposition temperature, and substrate temperature. Additionally, it provides insights into the core mechanisms of SiCN, such as the role of Dangling bonds and OH groups, and the effects of plasma surface treatment, which explain the differences from SiO2. Through this discussion, we aim to ultimately present the achievable advantages of applying the Cu/SiCN hybrid bonding structure.

Keywords

3D IC Package, Hybrid bonding, SiCN Dielectric, Cu/SiCN

Copper-Based Electrochemical CO2 Reduction and C2+ Products Generation: A Review

Jiwon Heo1 , Chaewon Seong1 , Vishal Burungale2 , Pratik Mane1 , Moo Sung Lee1†, and Jun-Seok Ha1,2†

1Department of Advanced Chemicals & Engineering, Chonnam National University, Gwangju, Republic of Korea, 2Optoelectronics Convergence Research Center, Chonnam National University, Gwangju, Republic of Korea

Journal of the Microelectronics and Packaging Society Vol. 30, No. 4, pp. 17-31.

Abstract

Amidst escalating global warming fueled by indiscriminate fossil fuel consumption, concerted efforts are underway worldwide to mitigate atmospheric carbon dioxide (CO2) levels. Electrochemical CO2 reduction technology is recognized as a promising and environmentally friendly approach to convert CO2 into valuable hydrocarbon compounds, deemed essential for achieving carbon neutrality. Copper, among the various materials used as CO2 reduction electrodes, is known as the sole metal capable of generating C2+ compounds. However, low conversion efficiency and selectivity have hindered its widespread commercialization. This review highlights diverse research endeavors to address these challenges. It explores various studies focused on utilizing copper-based electrodes for CO2 reduction, offering insights into potential solutions for advancing this crucial technology.

Keywords

Carbon dioxide reduction, Electrochemical catalysis, Copper-based electrodes, C2+ compound generation

Research Trends on Interface-type Resistive Switching Characteristics in Transition Metal Oxide

Dong-eun Kim, Geonwoo Kim, Hyung Nam Kim, and Hyung-Ho Park

Department of Materials Science and Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea

Journal of the Microelectronics and Packaging Society Vol. 30, No. 4, pp. 32-43.

Abstract

Resistive Random Access Memory (RRAM), based on resistive switching characteristics, is emerging as a next-generation memory device capable of efficiently processing large amounts of data through its fast operation speed, simple device structure, and high-density implementation. Interface type resistive switching offer the advantage of low operation currents without the need for a forming process. Especially, for RRAM devices based on transition metal oxides, various studies are underway to enhance the memory characteristics, including precise material composition control and improving the reliability and stability of the device. In this paper, we introduce various methods, such as doping of heterogeneous elements, formation of multilayer films, chemical composition adjustment, and surface treatment to prevent degradation of interface type resistive switching properties and enhance the device characteristics. Through these approaches, we propose the feasibility of implementing high-efficient next-generation non-volatile memory devices based on improved resistive switching properties.

Keywords

Interface-type, RRAM, Resistive switching, Transition metal oxide

A Study on the Development of a Program for Predicting Successful Welding of Electric Vehicle Batteries Using Laser Welding

Cheol-Hwan Kim1*, Chan-Su Moon1*, Kwan-Su Lee1 , Jin-Su Kim2 , Ae-Ryeong Jo3 , and Bo-Sung Shin1†

1Department of Optics and Mechatronics engineering, Pusan National University, 2, Busandaehak-ro 63beon gil, Geumjeong-gu, Busan, Republic of Korea, 2Department of Cogno-Mechatronics Engineering, Pusan National University, 2, Busandaehak-ro 63beon gil, Geumjeong-gu, Busan, Republic of Korea, 3Solution Division of Soft-Tech Internationl,Inc3, 168, Gasandigital1-ro, Geumcheon-gu, Seoul, Republic of Korea

Journal of the Microelectronics and Packaging Society Vol. 30, No. 4, pp. 44-49.

Abstract

In the global pursuit of carbon neutrality, the rapid increase in the adoption of electric vehicles (EVs) has led to a corresponding surge in the demand for batteries. To achieve high efficiency in electric vehicles, considerations of weight reduction and battery safety have become crucial factors. Copper and aluminum, both recognized as lightweight materials, can be effectively joined through laser welding. However, due to the distinct physical characteristics of these two materials, the process of joining them poses technical challenges. This study focuses on conducting simulations to identify the optimal laser parameters for welding copper and aluminum, with the aim of streamlining the welding process. Additionally, a Graphic User Interface (GUI) program has been developed using the Python language to visually present the results. Using machine learning image data, this program is anticipated to predict joint success and serve as a guide for safe and efficient laser welding. It is expected to contribute to the safety and efficiency of the electric vehicle battery assembly process.

Keywords

Laser welding, Battery, Random Forest, CFD, Heterojunction

A Numerical Study on the Effect of Initial Shape on Inelastic Deformation of Solder Balls under Various Mechanical Loading Conditions

Da-Hun Lee1 , Jae-Hyuk Lim1 , and Eun-Ho Lee1,2,3†

1School of Mechanical Engineering, Sungkyunkwan University, Seobu-ro 2066, Suwon-si, Gyeonggi-do, 16419, Republic of Korea, 2Department of Smart Fab. Technology, Sungkyunkwan University, Seobu-ro 2066, Suwon-si, Gyeonggi-do, 16419, Republic of Korea, 3Department of Intelligent Robotics, Sungkyunkwan University, Seobu-ro 2066, Suwon-si, Gyeonggi-do, 16419, Republic of Korea

Journal of the Microelectronics and Packaging Society Vol. 30, No. 4, pp. 50-60.

Abstract

Ball Grid Array (BGA) is a widely used package type due to its high pin density and good heat dissipation. In BGA, solder balls play an important role in electrically connecting the package to the PCB. Therefore, understanding the inelastic deformation of solder balls under various mechanical loads is essential for the robust design of semiconductor packages. In this study, the geometrical effect on the inelastic deformation and fracture of solder balls were analyzed by finite element analysis. The results showed that fracture occurred in both tilted and hourglass shapes under shear loading, and no fracture occurred in all cases under compressive loading. However, when bending was applied, only the tilted shape failed. When shear and bending loads were combined with compression, the stress triaxiality was maintained at a value less than zero and failure was suppressed. Furthermore, a comparison using the Lagrangian-Green strain tensor of the critical element showed that even under the same loading conditions, there was a significant difference in deformation depending on the shape of the solder ball.

Keywords

Numerical analysis, Inelastic deformation, Fracture, Solder, Packaging

Study on Sn-Ag-Fe Transient Liquid Phase Bonding for Application to Electric Vehicles Power Modules

Byungwoo Kim1 , Hyeri Go1 , Gyeongyeong Cheon2 , Yong-Ho Ko2 , and Yoonchul Sohn1†

1Dept. of Welding & Joining Science Engineering, Chosun University 309 Pilmoon-daero, Dong-gu, Gwangju 61452, Korea, 2Advanced Joining & Additive Manufacturing R&D Department, Korea Institute of Industrial Technology, 156 Gaetbeol-ro, Yeonsu-gu, Incheon 21999, Korea

Journal of the Microelectronics and Packaging Society Vol. 30, No. 4, pp. 61-68.

Abstract

In this study, Sn-3.5Ag-15.0Fe composite solder was manufactured and applied to TLP bonding to change the entire joint into a Sn-Fe IMC(intermetallic compound), thereby applying it as a high-temperature solder. The FeSn2 IMC formed during the bonding process has a high melting point of 513℃, so it can be stably applied to power modules for power semiconductors where the temperature rises up to 280℃ during use. As a result of applying ENIG surface treatment to both the chip and substrate, a multi-layer IMC structure of Ni3Sn4/FeSn2/Ni3Sn4 was formed at the joint. During the shear test, the fracture path showed that cracks developed at the Ni3Sn4/FeSn2 interface and then propagated into FeSn2. After 2hours of the TLP joining process, a shear strength of over 30 MPa was obtained, and in particular, there was no decrease in strength at all even in a shear test at 200°C. The results of this study can be expected to lead to materials and processes that can be applied to power modules for electric vehicles, which are being actively researched recently.

Keywords

Sn-Ag-Fe, composite solder, TLP bonding, power module

MAGICal Synthesis: Memory-Efficient Approach for Generative Semiconductor Package Image Construction

Yunbin Chang1 , Wonyong Choi2 , and Keejun Han1†

1School of Computer Engineering, Hansung University, 116, Samseongyo-ro 16-gil, Seongbuk-gu, Seoul, Republic of Korea, 2R&D Center, Genesem, 24, Songdogwahak-ro 84beon-gil, Yeonsu-gu, Incheon, Republic of Korea

Journal of the Microelectronics and Packaging Society Vol. 30, No. 4, pp. 69-78.

Abstract

With the rapid growth of artificial intelligence, the demand for semiconductors is enormously increasing everywhere. To ensure the manufacturing quality and quantity simultaneously, the importance of automatic defect detection during the packaging process has been re-visited by adapting various deep learning-based methodologies into automatic packaging defect inspection. Deep learning (DL) models require a large amount of data for training, but due to the nature of the semiconductor industry where security is important, sharing and labeling of relevant data is challenging, making it difficult for model training. In this study, we propose a new framework for securing sufficient data for DL models with fewer computing resources through a divide-and-conquer approach. The proposed method divides high-resolution images into pre-defined sub-regions and assigns conditional labels to each region, then trains individual sub-regions and boundaries with boundary loss inducing the globally coherent and seamless images. Afterwards, full-size image is reconstructed by combining divided sub-regions. The experimental results show that the images obtained through this research have high efficiency, consistency, quality, and generality.

Keywords

Data Augmentation, Generative Adversarial Networks, Artificial Intelligence, Performance Optimization

A Study on the Phase Change of Cubic Bi1.5Zn1.0Nb1.5O7(c-BZN) and the Corresponding Change in Dielectric Properties According to the Addition of Li2CO3

Yuseon Lee1 , Yunseok Kim1 , Seulwon Choi1 , Seongmin Han1 , and Kyoungho Lee1,2†

1Department of Electronic Materials, Devices and Equipment Engineering, Soonchunhyang University, 22 Soonchunhyang-ro, Asan-si, Chungcheongnam-do 31538, Korea, 2Department of Display and Materials Engineering, Soonchunhyang University, 22 Soonchunhyang-ro, Asan-si, Chungcheongnam-do 31538, Korea

Journal of the Microelectronics and Packaging Society Vol. 30, No. 4, pp. 79-85.

Abstract

A novel low-temperature co-fired ceramic (LTCC) dielectric, composed of (1-4x)Bi1.5Zn1.0Nb1.5O7-3xBi2Zn2/3Nb4/3O7-2xLiZnNbO4 (x=0.03-0.21), was synthesized through reactive liquid phase sintering of Bi1.5Zn1.0Nb1.5O7-xLi2CO3 ceramic at temperatures ranging from 850℃ to 920℃ for 4 hours. During sintering, Li2CO3 reacted with Bi1.5Zn1.0Nb1.5O7, resulting in the formation of Bi2Zn2/3Nb4/3O7, and LiZnNbO4. The resulting sintered body exhibited a relative sintering density exceeding 96% of the theoretical density. By altering the initial Li2CO3 content (x) and consequently modulating the volume fraction of Bi1.5Zn1.0Nb1.5O7, Bi2Zn2/3Nb4/3O7, and LiZnNbO4 in the final sintered body, a sample with high dielectric constant (εr), low dielectric loss (tan δ), and the temperature coefficient of dielectric constant (TCε) characterized by NP0 specification (TCε ≤ ±30 ppm/℃) was achieved. As the Li2CO3 content increased from x=0.03 mol to x=0.15 mol, the volume fraction of Bi2Zn2/3Nb4/3O7 and LiZnNbO4 in the composite increased, while the volume fraction of Bi1.5Zn1.0Nb1.5O7 decreased. Consequently, the dielectric constant (εr) of the composite materials varied from 148.38 to 126.99, the dielectric loss (tan δ) shifted from 5.29×10-4 to 3.31×10-4, and the temperature coefficient of dielectric constant (TCε) transitioned from -340.35 ppm/℃ to 299.67 ppm/℃. A dielectric exhibiting NP0 characteristics was achieved at x=0.09 for Li2CO3, with a dielectric constant (εr) of 143.06, a dielectric loss (tan δ) value of 4.31×10-4, and a temperature coefficient of dielectric constant (TCε) value of -9.98 ppm/℃. Chemical compatibility experiment with Ag electrode revealed that the developed composite material exhibited no reactivity with the Ag electrode during the co-firing process.

Keywords

Bi1.5Zn1.0Nb1.5O7, Li2CO3, Bi2Zn2/3Nb4/3O7, LiZnNbO4, LTCC, NP0

A Study on the Control of Hygroscopicity and Hardness in Polymer Surfaces

Jinil Kim1 , Young Nam Jung2 , Doa Kim3 , and Myung Yung Jeong1,2†

1Department of Cogno-Mechatronics Engineering, Pusan National University, Geumjeong-gu, Busan 46241, Korea, 2Department of Opto-Mechatronics Engineering, Pusan National University, Busan 46241, Korea, 3Materials and Components Research Division, Electronics and Telecommunications Research Institute (ETRI), 218 Gajeongno, Yuseong-gu, Daejeon, 34129 Republic of Korea

Journal of the Microelectronics and Packaging Society Vol. 30, No. 4, pp. 86-90.

Abstract

The packaging of electronic devices performs a protective function to ensure that their durability and reliability are not affected by changes in the operating environment caused by external factors. Recent advances in materials have led to ongoing research into bonded packaging of heterogeneous materials such as polymers and inorganic materials in electronic devices. In this packaging process, it is important to have a binding that joins the materials and ensures the operating environment, which includes adhesion to the substrate, corrosion and oxidation resistance through moisture removal, and durability. In this study, the hygroscopicity of the coating layer by modifying the polymer surface based on PVA was evaluated by controlling and measuring the contact angle, and the adhesion was confirmed by applying water-based ink and testing according to ASTM_D3363. For the durability of the polymer surface, the IPL post-treatment process was used to improve the hardness and toughness against applied voltage, and the pencil hardness test and nanoindentation test were conducted. Through this, we analyzed and proposed solutions to ensure the reliability and durability of polymer devices in polymer microfabrication against environmental factors such as moisture, temperature fluctuations and adhesion, and surface abrasion.

Keywords

Packaging, Hygroscopicity, Adhesion, IPL, Gradient Hardness

Tin Oxide-modulated to Cu(OH)2 Nanowires for Efficient Electrochemical Reduction of CO2 to HCOOH and CO

Chaewon Seong1 , Hyojung Bae2 , Sea Cho1 , Jiwon Heo1 , Eun Mi Han1†, and Jun-Seok Ha1†

1Department of Chemicals & Engineering, Chonnam National University, 77 Yong-bong-ro, Buk-gu, Gwangju 61186, Korea, 2Photonics Energy Materials Research Center, Korea Photonics Technology Institute (KOPTI), Cheomdanbencheo-ro 108 beon-gil 9, Buk-gu, Gwangju 61007, Korea

Journal of the Microelectronics and Packaging Society Vol. 30, No. 4, pp. 91-97.

Abstract

Electrochemical (EC) CO2 reduction is a promising method to convert CO2 into valuable hydrocarbon fuels and chemicals ecofriendly. Here, we report on a facile method to synthesize surface-controlled SnO2/Cu(OH)2 nanowires (NWs) and its EC reduction of CO2 to HCOOH and CO. The SnO2/Cu(OH)2 NWs (-16 mA/cm2 ) showed superior electrochemical performance compared to Cu(OH)2 NWs (-6 mA/cm2 ) at -1.0 V (vs. RHE). SnO2/Cu(OH)2 NWs showed the maximum Faradaic efficiency for conversion to HCOOH (58.01 %) and CO (29.72 %). The optimized catalyst exhibits a high C1 Faradaic efficiency stable electrolysis for 2 h in a KHCO3 electrolyte. This study facilitates the potential for the EC reduction of CO2 to chemical fuels.

Keywords

Electrochemical (EC), CO2 reduction (CO2RR), Copper-based catalysts, Tin oxide (SnO2)

Fabrication of Porous Cu Layers on Cu Pillars through Formation of Brass Layers and Selective Zn Etching, and Cu-to-Cu Flip-chip Bonding

Wan-Geun Lee1 , Kwang-Seong Choi2 , Yong-Sung Eom2 , and Jong-Hyun Lee1†

1Department of Materials Science & Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea, 2Low-Carbon Integration Tech, Creative Research Section, ETRI, Daejeon 34129, Republic of Korea

Journal of the Microelectronics and Packaging Society Vol. 30, No. 4, pp. 98-104.

Abstract

The feasibility of an efficient process proposed for Cu-Cu flip-chip bonding was evaluated by forming a porous Cu layer on Cu pillar and conducting thermo-compression sinter-bonding after the infiltration of a reducing agent. The porous Cu layers on Cu pillars were manufactured through a three-step process of Zn plating-heat treatment-Zn selective etching. The average thickness of the formed porous Cu layer was approximately 2.3 µm. The flip-chip bonding was accomplished after infiltrating reducing solvent into porous Cu layer and pre-heating, and the layers were finally conducted into sintered joints through thermo-compression. With reduction behavior of Cu oxides and suppression of additional oxidation by the solvent, the porous Cu layer densified to thickness of approximately 1.1 µm during the thermo-compression, and the CuCu flip-chip bonding was eventually completed. As a result, a shear strength of approximately 11.2 MPa could be achieved after the bonding for 5 min under a pressure of 10 MPa at 300 ℃ in air. Because that was a result of partial bonding by only about 50% of the pillars, it was anticipated that a shear strength of 20 MPa or more could easily be obtained if all the pillars were induced to bond through process optimization.

Keywords

Porous Cu layer, Flip-chip bonding, Zn plating, Zn selective etching, Thermo-compression sinter-bonding

Reliability of Cu Interconnect under Compressive Fatigue Deformation Varying Interfacial Adhesion Treatment

Min Ju Kim, Jeong A Heo, Jun Hyeok Hyun, and So-Yeon Lee

Department of Materials Science and Engineering, Kumoh National Institute of Technology, Gumi, Gyeongbuk 39177, Korea

Journal of the Microelectronics and Packaging Society Vol. 30, No. 4, pp. 105-111.

Abstract

Electronic devices have been evolved to be mechanically flexible that can be endured repetitive deformation. This evolution emphasizes the importance of long-term reliability in metal wiring connecting electronic components, especially under bending fatigue in compressed environments. This study investigated methods to enhance adhesion between copper (Cu) and polyimide (PI) substrates, aiming to improve the reliability of copper wiring under such conditions. We applied oxygen plasma treatment and introduced a chromium (Cr) adhesion layer to the polyimide substrate. Our findings revealed that these adhesion enhancement methods significantly affect compression fatigue behavior. Notably, the chromium adhesion layer, while showing weaker fatigue characteristics at 1.5% strain, demonstrated superior performance at 2.0% strain with no delamination, outperforming other methods. These results offer valuable insights for improving the reliability of flexible electronic devices, including reducing crack occurrence and enhancing fatigue resistance in their typical usage environments.

Keywords

Flexible device, Reliability, Interface adhesion, Metal film, Polyimide

Error Correction

Journal of the Microelectronics and Packaging Society Vol. 30, No. 4, pp. 112-112.

Abstract

Keywords