Nanotwinning-assisted structurally stable copper for fine-pitch redistribution layer in 2.5D/3D IC packaging

Cong Chen; Sheng-Jye Cherng; Chuan He; Chih-Chun Chung; Sijia Wang; Yu-Ting Huang; Shien Ping Feng

doi:10.1016/j.jmrt.2023.11.011

Nanotwinning-assisted structurally stable copper for fine-pitch redistribution layer in 2.5D/3D IC packaging

Cong Chen, Sheng-Jye Cherng, Chuan He, Chih-Chun Chung, Sijia Wang, Yu-Ting Huang^*, Shien Ping Feng^*

^*Corresponding author for this work

Department of Systems Engineering

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

5 Citations (Scopus)

116 Downloads (CityUHK Scholars)

Abstract

The redistribution layer (RDL) is crucial for fanning out circuits and for 2.5D/3D IC packaging. As device density increases, RDL CD/pitch must shrink. During RDL circuit fabrication, the etching process is necessary to remove the exposed sputtered Cu seed layer and Ti barrier layer. Unfortunately, this process unavoidably etches and roughens the Cu surface of the RDL. As the post-plating resting time (q-time) increases, the Cu surface oxidizes, resulting in even worse surface roughness after etching. This roughness causes contact resistance and electromigration issues when the RDL linewidth shrinks. This paper presents a composite Cu structure that combines fine grains and nanotwins, which is structurally stable and can effectively resist surface damage even after extended periods, offering a promising solution for achieving finer RDL in advanced packaging technologies with a longer electromigration lifetime than regular coarse-grain lines. © 2023 The Authors.

Original language	English
Pages (from-to)	4883-4890
Journal	Journal of Materials Research and Technology
Volume	27
Online published	7 Nov 2023
DOIs	https://doi.org/10.1016/j.jmrt.2023.11.011
Publication status	Published - Nov 2023

Funding

The authors acknowledge the financial support received from the startup grant in City University of Hong Kong and the General Research Fund of the Research Grants Council of Hong Kong Special Administrative Region, China under Award Number 17207422. The authors would also like to express their gratitude for the material and technical support provided by Doctech HK Ltd.

Research Keywords

3D IC package
Composite copper
Fine-pitch RDL

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This full text is made available under CC-BY-NC-ND 4.0. https://creativecommons.org/licenses/by-nc-nd/4.0/

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title = "Nanotwinning-assisted structurally stable copper for fine-pitch redistribution layer in 2.5D/3D IC packaging",

abstract = "The redistribution layer (RDL) is crucial for fanning out circuits and for 2.5D/3D IC packaging. As device density increases, RDL CD/pitch must shrink. During RDL circuit fabrication, the etching process is necessary to remove the exposed sputtered Cu seed layer and Ti barrier layer. Unfortunately, this process unavoidably etches and roughens the Cu surface of the RDL. As the post-plating resting time (q-time) increases, the Cu surface oxidizes, resulting in even worse surface roughness after etching. This roughness causes contact resistance and electromigration issues when the RDL linewidth shrinks. This paper presents a composite Cu structure that combines fine grains and nanotwins, which is structurally stable and can effectively resist surface damage even after extended periods, offering a promising solution for achieving finer RDL in advanced packaging technologies with a longer electromigration lifetime than regular coarse-grain lines. {\textcopyright} 2023 The Authors.",

keywords = "3D IC package, Composite copper, Fine-pitch RDL",

author = "Cong Chen and Sheng-Jye Cherng and Chuan He and Chih-Chun Chung and Sijia Wang and Yu-Ting Huang and Feng, {Shien Ping}",

year = "2023",

month = nov,

doi = "10.1016/j.jmrt.2023.11.011",

language = "English",

volume = "27",

pages = "4883--4890",

journal = "Journal of Materials Research and Technology",

issn = "2238-7854",

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TY - JOUR

T1 - Nanotwinning-assisted structurally stable copper for fine-pitch redistribution layer in 2.5D/3D IC packaging

AU - Chen, Cong

AU - Cherng, Sheng-Jye

AU - He, Chuan

AU - Chung, Chih-Chun

AU - Wang, Sijia

AU - Huang, Yu-Ting

AU - Feng, Shien Ping

PY - 2023/11

Y1 - 2023/11

N2 - The redistribution layer (RDL) is crucial for fanning out circuits and for 2.5D/3D IC packaging. As device density increases, RDL CD/pitch must shrink. During RDL circuit fabrication, the etching process is necessary to remove the exposed sputtered Cu seed layer and Ti barrier layer. Unfortunately, this process unavoidably etches and roughens the Cu surface of the RDL. As the post-plating resting time (q-time) increases, the Cu surface oxidizes, resulting in even worse surface roughness after etching. This roughness causes contact resistance and electromigration issues when the RDL linewidth shrinks. This paper presents a composite Cu structure that combines fine grains and nanotwins, which is structurally stable and can effectively resist surface damage even after extended periods, offering a promising solution for achieving finer RDL in advanced packaging technologies with a longer electromigration lifetime than regular coarse-grain lines. © 2023 The Authors.

AB - The redistribution layer (RDL) is crucial for fanning out circuits and for 2.5D/3D IC packaging. As device density increases, RDL CD/pitch must shrink. During RDL circuit fabrication, the etching process is necessary to remove the exposed sputtered Cu seed layer and Ti barrier layer. Unfortunately, this process unavoidably etches and roughens the Cu surface of the RDL. As the post-plating resting time (q-time) increases, the Cu surface oxidizes, resulting in even worse surface roughness after etching. This roughness causes contact resistance and electromigration issues when the RDL linewidth shrinks. This paper presents a composite Cu structure that combines fine grains and nanotwins, which is structurally stable and can effectively resist surface damage even after extended periods, offering a promising solution for achieving finer RDL in advanced packaging technologies with a longer electromigration lifetime than regular coarse-grain lines. © 2023 The Authors.

KW - 3D IC package

KW - Composite copper

KW - Fine-pitch RDL

UR - http://www.scopus.com/inward/record.url?scp=85177205770&partnerID=8YFLogxK

UR - https://www.scopus.com/record/pubmetrics.uri?eid=2-s2.0-85177205770&origin=recordpage

U2 - 10.1016/j.jmrt.2023.11.011

DO - 10.1016/j.jmrt.2023.11.011

M3 - RGC 21 - Publication in refereed journal

SN - 2238-7854

VL - 27

SP - 4883

EP - 4890

JO - Journal of Materials Research and Technology

JF - Journal of Materials Research and Technology

ER -

Nanotwinning-assisted structurally stable copper for fine-pitch redistribution layer in 2.5D/3D IC packaging

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Research Keywords

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GRF: Development of Ionic-thermoelectric Material and Device for Converting Low-grade Heat to Electricity

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Nanotwinning-assisted structurally stable copper for fine-pitch redistribution layer in 2.5D/3D IC packaging

Abstract

Funding

Research Keywords

Publisher's Copyright Statement

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GRF: Development of Ionic-thermoelectric Material and Device for Converting Low-grade Heat to Electricity

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