Sug-hun Hong

Fabrication of body-tied FinFETs (Omega MOSFETs) using bulk Si wafers

Nano scale body-tied FinFETs have been firstly fabricated. They have fin top width of 30 nm, fin bottom width of 61 nm, fin height of 99 nm, and gate length of 60 nm. This Omega MOSFET shows excellent transistor characteristics, such as very low subthreshold swing, Drain Induced Barrier Lowering (DIBL) of 24 mV/V, almost no body bias effect, and orders of magnitude lower I/sub SUB//I/sub D/ than planar type DRAM cell transistors.

Improvement of Performance and Data Retention Characteristics of Sub-50nm DRAM by HfSiON Gate Dielectric

For the first time, we have successfully integrated HfSiON gate dielectric to DRAM and obtained excellent data retention time. Lower gate leakage current and better mobility of HfSiON than plasma nitrided oxide resulted in a 22% smaller propagation delay measured at CMOS inverter as well as one order of magnitude lower stand-by current for DRAM. Optimized gate poly-Si reoxidation and high Vt of HfSiON cell Tr increased DRAM data retention time as much as 2 times longer than plasma nitrided oxide. We demonstrated that HfSiON could enhance performance and be beneficial to date retention time of high thermal budget DRAM at the same time.

The development of dual gate poly scheme with plasma nitrided gate oxide for mobile high performance DRAMs: plasma process monitoring and the correlation with electrical results

The in-line plasma process monitoring was successfully performed with non-contact direct measurement (NCDM) tool and its results were well matched with those from devices. Using this monitoring method, we developed a plasma nitrided gate oxide process for mobile DRAMs with low operating voltage. We confirm that plasma nitrided gate oxide can block the boron penetration in DRAMs, which has higher thermal budget than other devices, and that the NCDM tool can be used for checking the degree of plasma nitridation. We assure that the NCDM tool is a time-effective tool for plasma nitridation process development.