IBM’s High Performance 65 nm SOI Process
Figure 8 – Ion versus Ioff distribution curve for the high performance 65 nm SOI process
In technical session 3.3 at IEDM 2005, the IBM-Sony-Toshiba-AMD (ISTA) alliance disclosed some intriguing details about its high performance 65 nm SOI process, targeted for applications such as IBM’s POWERPC and CELL processors. The high performance 65 nm SOI process is said to contain advanced features such as four silicon stressors: the NMOS stress liner, the PMOS stress liner, stress memorization, and embedded SiGe. The reported DC Idsat drive currents as seen in Figure 8 are 700/1137 uA/um for PMOS/NMOS and Ioff leakage current of 200 nA/um at 1.0 V nominal. The reported AC Idsat drive currents are 735/1259 uA/um for PMOS/NMOS and Ioff leakage current of 200 nA/um at 1.0 V nominal. These reported values are slightly different from the values reported in the paper on silicon stressors, paper 10.5. In that paper, the Idsat current as reported as follows:
At 1.0V, NMOS Idsat = 1080 uA/um and PMOS Idsat = 710uA/um at Ioff = 200nA/um have been achieved for the full 4 way stress CMOS integration. Correcting for self-heating the values correspond to an Idsat of 1145 uA/um for NMOS and 740 uA/um for PMOS.
The reported Idsat drive currents are roughly comparable to those reported by Intel on its 65 nm high performance CMOS process when adjusted for the same Ioff leakage levels (Idsat = 710/1210 uA/um PMOS/NMOS at Ioff = 100 nA/um). However, paper 10.5 states that the PMOS transistor drive current in the high performance SOI process can be further increased with improvements in the embedded SiGe integration technique. Since embedded SiGE is designed to provide compressive stress in PMOS transistors, it can only enhance the performance of PMOS transistors. Nevertheless, paper 10.5 reports that with successive improvements in SiGe integration, PMOS Idsat of 820 uA/um have been measured at Ioff of 200 nA/um. The increase in PMOS Idsat is the highest PMOS drive current reported to date, and the CV/I performance of 1.25 ps is also the best reported to date. As a result, the 65 nm SOI process from the ISTA alliance should be able to experience a quick jump in performance once the improvements in the embedded SiGe integration process are successfully introduced into the manufacturing process.
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