Metallization-free silver sinter bonding to silicon via in situ decomposition of silver oxalate

• Published in: Materials letters 2021-10, Vol.300, p.130205, Article 130205
• Main Authors: Kawabata, Rei, Matsuda, Tomoki, Seo, Ryotaro, Hirose, Akio
• Format: Article
• Language: English
• Subjects: Bonding strength; Decomposition; Electronic materials; Materials science; Metallizing; Nanomaterial; Shear strength; Silicon; Silicon dioxide; Silicon substrates; Silver; Silver oxalate; Sinter Bonding; Thermal decomposition
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2021.130205

[Display omitted] •Ag oxalate started to decompose to pure Ag at approximately 200 °C.•Ag oxalate decomposition enabled direct sinter joining of Si-based materials.•Atomic-scale Ag can be responsible for the large-scale adhesion to SiO2.•Bonding strength achieved 29 MP at a bonding temperature of 250 °C. Metallization-free Ag sinter bonding to Si and SiO2 substrates was achieved via the thermal decomposition of Ag oxalate. Ag oxalate generated atomic-scale Ag through decomposition at approximately 200 °C and transformed into sintered Ag. Ag derived from Ag oxalate successfully bonded to Si substrates through close contact formation with Si surface oxide. Similarly, amorphous and α-quartz SiO2 substrates were directly bonded with Ag. These results indicate that the atomic-scale Ag generated on SiO2 contributed to interface formation over a large area. Moreover, the joints of the bare Si chip and metal substrate showed a maximum shear strength of 29 MPa at a bonding temperature of 250 °C and a bonding pressure of 5 MPa. The in-situ generation of Ag through the decomposition of Ag precursors can facilitate the direct bonding of electronic materials, making the proposed method a promising one for electronics applications.