Hydrophilic thermocompression bonding of single-crystalline 3C-SiC thin film on sapphire substrate

Microelectronic devices for harsh environment applications require new wafer bonding methods that can overcome the large thermal mismatch between functional layer and supporting substrate during bonding process. This paper presents a bonding strategy that leverages the thermocompression bond formati...

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Main Authors: Abdul Ahad Khan, Tuan-Khoa Nguyen, Abbhiraj Singh, Takahiro Namazu, Dzung Viet Dao, Yong Zhu
Format: Article
Language:English
Published: Elsevier 2025-07-01
Series:Next Materials
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Online Access:http://www.sciencedirect.com/science/article/pii/S2949822825002631
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author Abdul Ahad Khan
Tuan-Khoa Nguyen
Abbhiraj Singh
Takahiro Namazu
Dzung Viet Dao
Yong Zhu
author_facet Abdul Ahad Khan
Tuan-Khoa Nguyen
Abbhiraj Singh
Takahiro Namazu
Dzung Viet Dao
Yong Zhu
author_sort Abdul Ahad Khan
collection DOAJ
description Microelectronic devices for harsh environment applications require new wafer bonding methods that can overcome the large thermal mismatch between functional layer and supporting substrate during bonding process. This paper presents a bonding strategy that leverages the thermocompression bond formation between a wide band gap semiconductor (i.e., silicon carbide (SiC)) and a robust substrate (i.e., sapphire) for the first time for harsh environment applications. The wafer bonding process was executed through chemical bonding, facilitated with the hydrophilic surfaces on both silicon carbide and sapphire surfaces. The enhanced hydrophilicity was obtained by plasma treatment, resulting in the formation of hydroxyl groups (-OH) on the bonding surfaces. The bonding was done immediately after oxygen plasma activation steps to avoid any loss of the generated -OH groups. To further assist bonding through the hydrophilic surfaces, the bonding temperature of 250 °C and pressing force of 10 kN were applied on a 20 mm x 20 mm bonding sample for 30 minutes to form strong chemical bonds (Si-C-O-Al). The bonding results of this study revealed a bonding strength of 0.6 MPa at the SiC/sapphire interface. This strength is attributed to the presence of an ∼25 nm amorphous transition layer formed at the interface between sapphire and SiC. Furthermore, high-resolution STEM results showed that both surfaces were atomically bonded through the transition layer with enriched carbon element. Our thermocompression bonding technique enables the formation of single-crystalline SiC thin-film on Sapphire (SiCOS) heterostructures, which offers great potentials for power electronics and MEMS devices in harsh environment applications.
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spelling doaj-art-4e53de0f13d644e4b3b0b8b144b157df2025-08-20T03:48:14ZengElsevierNext Materials2949-82282025-07-01810074510.1016/j.nxmate.2025.100745Hydrophilic thermocompression bonding of single-crystalline 3C-SiC thin film on sapphire substrateAbdul Ahad Khan0Tuan-Khoa Nguyen1Abbhiraj Singh2Takahiro Namazu3Dzung Viet Dao4Yong Zhu5School of Engineering and Built Environment, Griffith University, Gold Coast Campus, Gold Coast, QLD 4222, Australia; Corresponding author.Queensland Micro and Nanotechnology Centre (QMNC), Griffith University, Brisbane, QLD 4111, AustraliaKyoto University of Advanced Science, 18 Yamanouchigotanda-cho, Ukyo, Kyoto 615-8577, JapanKyoto University of Advanced Science, 18 Yamanouchigotanda-cho, Ukyo, Kyoto 615-8577, JapanSchool of Engineering and Built Environment, Griffith University, Gold Coast Campus, Gold Coast, QLD 4222, Australia; Queensland Micro and Nanotechnology Centre (QMNC), Griffith University, Brisbane, QLD 4111, AustraliaSchool of Engineering and Built Environment, Griffith University, Gold Coast Campus, Gold Coast, QLD 4222, Australia; Queensland Micro and Nanotechnology Centre (QMNC), Griffith University, Brisbane, QLD 4111, AustraliaMicroelectronic devices for harsh environment applications require new wafer bonding methods that can overcome the large thermal mismatch between functional layer and supporting substrate during bonding process. This paper presents a bonding strategy that leverages the thermocompression bond formation between a wide band gap semiconductor (i.e., silicon carbide (SiC)) and a robust substrate (i.e., sapphire) for the first time for harsh environment applications. The wafer bonding process was executed through chemical bonding, facilitated with the hydrophilic surfaces on both silicon carbide and sapphire surfaces. The enhanced hydrophilicity was obtained by plasma treatment, resulting in the formation of hydroxyl groups (-OH) on the bonding surfaces. The bonding was done immediately after oxygen plasma activation steps to avoid any loss of the generated -OH groups. To further assist bonding through the hydrophilic surfaces, the bonding temperature of 250 °C and pressing force of 10 kN were applied on a 20 mm x 20 mm bonding sample for 30 minutes to form strong chemical bonds (Si-C-O-Al). The bonding results of this study revealed a bonding strength of 0.6 MPa at the SiC/sapphire interface. This strength is attributed to the presence of an ∼25 nm amorphous transition layer formed at the interface between sapphire and SiC. Furthermore, high-resolution STEM results showed that both surfaces were atomically bonded through the transition layer with enriched carbon element. Our thermocompression bonding technique enables the formation of single-crystalline SiC thin-film on Sapphire (SiCOS) heterostructures, which offers great potentials for power electronics and MEMS devices in harsh environment applications.http://www.sciencedirect.com/science/article/pii/S2949822825002631Silicon CarbideSapphireHydrophilicityPlasma activationSiC on Sapphire (SiCOS)Thermocompression bonding mechanisms
spellingShingle Abdul Ahad Khan
Tuan-Khoa Nguyen
Abbhiraj Singh
Takahiro Namazu
Dzung Viet Dao
Yong Zhu
Hydrophilic thermocompression bonding of single-crystalline 3C-SiC thin film on sapphire substrate
Next Materials
Silicon Carbide
Sapphire
Hydrophilicity
Plasma activation
SiC on Sapphire (SiCOS)
Thermocompression bonding mechanisms
title Hydrophilic thermocompression bonding of single-crystalline 3C-SiC thin film on sapphire substrate
title_full Hydrophilic thermocompression bonding of single-crystalline 3C-SiC thin film on sapphire substrate
title_fullStr Hydrophilic thermocompression bonding of single-crystalline 3C-SiC thin film on sapphire substrate
title_full_unstemmed Hydrophilic thermocompression bonding of single-crystalline 3C-SiC thin film on sapphire substrate
title_short Hydrophilic thermocompression bonding of single-crystalline 3C-SiC thin film on sapphire substrate
title_sort hydrophilic thermocompression bonding of single crystalline 3c sic thin film on sapphire substrate
topic Silicon Carbide
Sapphire
Hydrophilicity
Plasma activation
SiC on Sapphire (SiCOS)
Thermocompression bonding mechanisms
url http://www.sciencedirect.com/science/article/pii/S2949822825002631
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