Random Telegraph Signal in Flash Memory: Its Impact on Scaling of Multilevel Flash Memory Beyond the 90-nm Node

Threshold-voltage (Vth) fluctuation due to random telegraph signal (RTS) in flash memory was observed for the first time. A large amount of data of Vth fluctuation was acquired by using a 90-nm-node memory array, and it was confirmed that a few memory cells have large RTS fluctuation exceeding 0.2 V. It was found that program-and-erase cycles increase Vth amplitude in a flash memory. It was also found by simulation and measurement that tail-bits are generated due to RTS in multilevel flash operation. The amount of Vth broadening due to the tail-bits was estimated to become larger as the scaling of memory cells advances and reaches more than 0.3 V in the 45-nm node. These results thus demonstrate that RTS will become a prominent issue in designing multilevel flash memory in the 45-nm node and beyond.     

A Novel Strain Method for Enhancement of 90-nm Node and Beyond FUSI-Gated CMOS Performance

A novel strain engineering technique for a fully silicided (FUSI) metal gate called contact etch stop layer (CESL)-enveloped FUSI was developed for the first time. A CESL was deposited prior to the FUSI RTP2 (the second rapid thermal process of FUSI gate formation) to confine the Ni_xSi FUSI. Then, the phase transfer and volume change of the enveloped FUSI after RTP2 induced a tensile stress to enhance I_ON. For example, 500 degC RTP2 induced 1-GPa tensile stress on a blanket wafer test and gained 10% improvement in the I_ON of the n-channel metal-oxide-semiconductor. The mechanisms of the improvement were also nicely supported by transmission-electron-microscope cross-section analysis, X-ray-diffraction spectrum, and simulation confirmation data     

Shallow Trench Isolation for the 45-nm CMOS Node and Geometry Dependence of STI Stress on CMOS Device Performance

In the present work, a high aspect ratio process (HARP) using a new O₃/TEOS based sub atmospheric chemical vapor deposition process was implemented as STI gapfill in sub-65-nm CMOS. Good gapfill performance up to aspect ratios greater than 10:1 was demonstrated. Since the HARP process does not attack the STI liner as compared to HDP, a variety of different STI liners can be implemented. By comparing HARP with HDP, the geometry dependence of nand p-FET performance due to STI stress is discussed     

A High Gain and Low Supply Voltage LNA for the Direct Conversion Application With 4-KV HBM ESD Protection in 90-nm RF CMOS

A 2.4-GHz low noise amplifier (LNA) for the direct conversion application with high power gain, low supply voltage and plusmn4 KV human body model (HBM) electrostatic discharge (ESD) protection level implemented by a 90-nm RF CMOS technology is demonstrated. At 12.9 mA of current consumption with a supply voltage of 1.0 V, the LNA delivers a power gain of 21.9 dB and the noise figure (NF) of 3.2 dB, while maintaining the input and output return losses below -11 dB and -18.3 dB, respectively. The power gain and NF are only 0.2 dB lower and 0.64 dB higher than those of LNA without ESD protection