A Si-Interposer with Buried Cu Metal Stripes and Bonded to Si-Substrate Backside for Security IC Chips

IC secure packaging physically protects cryptographic processors against implementation attacks. A Si substrate of a CMOS IC chip in a 0.13 μm technology is thinned to 20 μm from its backside and bonded with a Si interposer buried with Cu stripes of 50 μm and 20 μm in depth and in width, respectively, to form “Backside Bonded Buried Metal (TBM).” The IC chips with TBM stripes form the internally hidden, physically unbreakable, electromagnetic and optical shielding structures. Although their presence is observable once an attacker uses an infrared microscope, the TBM stripes can obviate the inherent vulnerability of flip-chip assembly against Si backside attacks through spontaneous side-channel emission as well as intentional fault injection.