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For high-volume production of 3D-stacked chips with through-silicon-vias (TSVs), wafer-scale bonding offers lower production cost compared with bump bond technology and is promising for interconnect pitches smaller than 5 µ using available tooling. Prior work has presented wafer-scale integration with tungsten TSV for low-power applications. This paper reports the first use of low-temperature oxide bonding and copper TSV to stack high performance cache cores manufactured in 45 nm Silicon On Insulator-Complementary Metal Oxide Semiconductor (SOI-CMOS) embedded DRAM (EDRAM) having 12 to 13 copper wiring levels per strata and upto 11000 TSVs at 13 µm pitch for power and signal delivery. The wafers are thinned to 13 µm using grind polish and etch. TSVs are defined post bonding and thinning using conventional alignment techniques. Up to four additional metal levels are formed post bonding and TSV definition. A key feature of this process is its compatibility with the existing high performance POWER7™ EDRAM core requiring neither modification of the existing CMOS fabrication process nor re-design since the TSV RC characteristic is similar to typical 100–200 µm length wiring load enabling 3D macro-to-macro signaling without additional buffering Hardware measurements show no significant impact on device drive and off-current. Functional test at wafer level confirms 2.1 GHz 3D stacked EDRAM operation.

For the first time, we have demonstrated a 32nm high-k/metal gate (HK-MG) low power CMOS platform technology with low standby leakage transistors and functional high-density SRAM with a cell size of 0.157 μm2. Record NMOS/PMOS drive currents of 1000/575 μA/μm, respectively, have been achieved at 1 nA/μm off-current and 1.1V Vdd with a low cost process. With this high performance transistor, Vdd can be further scaled to 1.0V for active power reduction. Through aggressive EOT scaling and band-edge work-function metal gate stacks, appropriate Vts and superior short channel control has been achieved for both NMOS and PMOS at L gate=30nm. Compared to SiON-Poly, 30% RO delay reduction has been demonstrated with HK-MG devices. 40% Vt mismatch reduction has been shown with the Tinv scaling. Furthermore, it has been shown that the 1/f noise and transistor reliability exceed the technology requirements. © 2008 IEEE.