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

Abstract

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.