Low-Temperature Al-Al Thermocompression Bonding with Sn Oxidation Protect Layer for Wafer-Level Hermetic Sealing

Shiro Satoh; Hideyuki Fukushi; Masayoshi Esashi; Shuji Tanaka

doi:10.1002/ecj.11975

Low-Temperature Al-Al Thermocompression Bonding with Sn Oxidation Protect Layer for Wafer-Level Hermetic Sealing

Shiro Satoh, Hideyuki Fukushi, Masayoshi Esashi, Shuji Tanaka

Research output: Contribution to journal › Article › peer-review

Abstract

This paper describes hermetic seal wafer bonding using Al covered with thin Sn as an antioxidation layer. The bonding temperature is below 400 °C, which is the maximum temperature of CMOS-LSI backend process. Gas tightness over 3000 h at room temperature and sealing stability through heat treatment under a typical reflow condition of 260 °C for 10 min were confirmed for samples bonded at 370 °C and 380 °C. A key for successful hermetic seal bonding is relatively high bonding pressure and stress concentration on sealing frames as narrow as several micrometers. The results of SEM and EDX analysis suggested that the bonding was due to direct Al-Al bonding, while Sn was diffused sparsely among Al grain boundaries. The developed bonding technology is usable for wafer-level integration of LSI and MEMS in conjunction with hermetic sealing.

Original language	English
Pages (from-to)	43-50
Number of pages	8
Journal	Electronics and Communications in Japan
Volume	100
Issue number	8
DOIs	https://doi.org/10.1002/ecj.11975
Publication status	Published - 2017 Aug

Keywords

Al-Al thermocompression bonding
CMOS-LSI backend process
Sn antioxidation layer
hermetic seal

ASJC Scopus subject areas

Signal Processing
Physics and Astronomy(all)
Computer Networks and Communications
Electrical and Electronic Engineering
Applied Mathematics

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10.1002/ecj.11975

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title = "Low-Temperature Al-Al Thermocompression Bonding with Sn Oxidation Protect Layer for Wafer-Level Hermetic Sealing",

abstract = "This paper describes hermetic seal wafer bonding using Al covered with thin Sn as an antioxidation layer. The bonding temperature is below 400 °C, which is the maximum temperature of CMOS-LSI backend process. Gas tightness over 3000 h at room temperature and sealing stability through heat treatment under a typical reflow condition of 260 °C for 10 min were confirmed for samples bonded at 370 °C and 380 °C. A key for successful hermetic seal bonding is relatively high bonding pressure and stress concentration on sealing frames as narrow as several micrometers. The results of SEM and EDX analysis suggested that the bonding was due to direct Al-Al bonding, while Sn was diffused sparsely among Al grain boundaries. The developed bonding technology is usable for wafer-level integration of LSI and MEMS in conjunction with hermetic sealing.",

keywords = "Al-Al thermocompression bonding, CMOS-LSI backend process, Sn antioxidation layer, hermetic seal",

author = "Shiro Satoh and Hideyuki Fukushi and Masayoshi Esashi and Shuji Tanaka",

note = "Funding Information: This study was supported by ?Creation of Innovation Center for Advanced Interdisciplinary Research Areas Program?, the Ministry of Education, Culture, Sports, Science and Technology. We are also thankful to a Chief Engineer Hirofumi Watanabe at RICOH Institute of Technology, and Mr. Yukihito Satoh and Mr. Kasuke Anzai at RICOH Fundamental Technology Research Center to advise and support us. Publisher Copyright: {\textcopyright} 2017 Wiley Periodicals, Inc.",

year = "2017",

month = aug,

doi = "10.1002/ecj.11975",

language = "English",

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AU - Satoh, Shiro

AU - Fukushi, Hideyuki

AU - Esashi, Masayoshi

AU - Tanaka, Shuji

N1 - Funding Information: This study was supported by ?Creation of Innovation Center for Advanced Interdisciplinary Research Areas Program?, the Ministry of Education, Culture, Sports, Science and Technology. We are also thankful to a Chief Engineer Hirofumi Watanabe at RICOH Institute of Technology, and Mr. Yukihito Satoh and Mr. Kasuke Anzai at RICOH Fundamental Technology Research Center to advise and support us. Publisher Copyright: © 2017 Wiley Periodicals, Inc.

PY - 2017/8

Y1 - 2017/8

N2 - This paper describes hermetic seal wafer bonding using Al covered with thin Sn as an antioxidation layer. The bonding temperature is below 400 °C, which is the maximum temperature of CMOS-LSI backend process. Gas tightness over 3000 h at room temperature and sealing stability through heat treatment under a typical reflow condition of 260 °C for 10 min were confirmed for samples bonded at 370 °C and 380 °C. A key for successful hermetic seal bonding is relatively high bonding pressure and stress concentration on sealing frames as narrow as several micrometers. The results of SEM and EDX analysis suggested that the bonding was due to direct Al-Al bonding, while Sn was diffused sparsely among Al grain boundaries. The developed bonding technology is usable for wafer-level integration of LSI and MEMS in conjunction with hermetic sealing.

AB - This paper describes hermetic seal wafer bonding using Al covered with thin Sn as an antioxidation layer. The bonding temperature is below 400 °C, which is the maximum temperature of CMOS-LSI backend process. Gas tightness over 3000 h at room temperature and sealing stability through heat treatment under a typical reflow condition of 260 °C for 10 min were confirmed for samples bonded at 370 °C and 380 °C. A key for successful hermetic seal bonding is relatively high bonding pressure and stress concentration on sealing frames as narrow as several micrometers. The results of SEM and EDX analysis suggested that the bonding was due to direct Al-Al bonding, while Sn was diffused sparsely among Al grain boundaries. The developed bonding technology is usable for wafer-level integration of LSI and MEMS in conjunction with hermetic sealing.

KW - Al-Al thermocompression bonding

KW - CMOS-LSI backend process

KW - Sn antioxidation layer

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Low-Temperature Al-Al Thermocompression Bonding with Sn Oxidation Protect Layer for Wafer-Level Hermetic Sealing

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Keywords

ASJC Scopus subject areas

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