Study of a Negative Threshold Voltage Shift in Positive Bias Temperature Instability and a Positive Threshold Voltage Shift the Negative Bias Temperature Instability of Yttrium-Doped HfO2Gate Dielectrics

2010 ◽  
Vol 49 (4) ◽  
pp. 04DC24 ◽  
Author(s):  
Motoyuki Sato ◽  
Satoshi Kamiyama ◽  
Takeo Matsuki ◽  
Dai Ishikawa ◽  
Tetsuro Ono ◽  
...  
Author(s):  
S Suvarna ◽  
K Rajesh ◽  
T Radhu

High speed digital multipliers are most efficiently used in many applications such as Fourier transform, discrete cosine transforms, and digital filtering. The throughput of the multipliers is based on speed of the multiplier, and then the entire performance of the circuit depends on it. The pMOS transistor in negative bias cause negative bias temperature instability (NBTI), which increases the threshold voltage of the transistor and reduces the multiplier speed. Similarly, the nMOS transistor in positive bias cause positive bias temperature instability (PBTI).These effects reduce the transistor speed and the system may fail due to timing violations. So here a new multiplier was designed with novel adaptive hold logic (AHL) using Radix-4 Modified Booth Multiplier. By using Radix-4 Modified Booth Encoding (MBE), we can reduce the number of partial products by half. Modified booth multiplier helps to provide higher throughput with low power consumption. This can adjust the AHL circuit to reduce the performance degradation. The expected result will be reduce threshold voltage, increase throughput and speed and also reduce power. This modified multiplier design is coded by Verilog and simulated using Xilinx ISE 12.1 and implemented in Spartan 3E FPGA kit.


2007 ◽  
Vol 17 (01) ◽  
pp. 129-141
Author(s):  
N. A. CHOWDHURY ◽  
D. MISRA ◽  
N. RAHIM

This work studies the effects of negative bias temperature instability (NBTI) on p-channel MOSFETS with TiN/HfSi x O y (20% SiO 2 based high-κ gate stacks under different gate bias and elevated temperature conditions. For low bias conditions, threshold voltage shift (ΔVT) is most probably due to the mixed degradation within the bulk high-κ. For moderately high bias conditions, H-species dissociation in the presence of holes and subsequent diffusion may be initially responsible for interface state and positively charged bulk trap generation. Initial time, temperature and oxide electric field dependence of ΔVT in our devices shows an excellent match with that of SiO 2 based devices, which is explained by reaction-diffusion (R-D) model of NBTI. Under high bias condition at elevated temperatures, due to higher Si - H bond-annealing/bond-breaking ratio, the experimentally observed absence of the impact ionization induced hot holes at the interfacial layer (IL)/ Si interface probably limits the interface state generation and ΔVT as they quickly reach saturation.


2008 ◽  
Vol 22 (05) ◽  
pp. 337-341
Author(s):  
YONG K. LEE ◽  
SUNG-HOON CHOA

The a- Si:H thin film transistors TFT with silicon nitride as a gate insulator have been stressed with negative and positive bias to realize the instability mechanisms. With proposed BT-TFT and FB-TFT devices, it is found that the threshold voltages of both BT-TFT and BT-TFT devices are positively shifted under positive bias stress and then negatively shifted for negative bias stress. The positive threshold voltage shift is due to the electron trapping in the silicon nitride or at the a- Si:H /silicon nitride interface. The negative threshold voltage shift is mainly due to hole trapping and/or electron de-trapping in the silicon nitride or at the a- Si:H /silicon nitride interface. The positive or negative threshold voltage shift keeps increasing with increasing positive or negative gate bias for both BT-TFT and FB-TFT devices. However, as far as the threshold voltage shift slope is concerned, under positive bias stress, both BT-TFT and FB-TFT devices are similar to each other. On the other hand, under negative bias stress, BT-TFT shift amount is much less than one for the FB-TFT device.


2008 ◽  
Vol 1066 ◽  
Author(s):  
Chyuan-Haur Kao ◽  
W. H. Sung

ABSTRACTThis paper studies the impact of LTPS (low temperature polycrystalline silicon) TFTs with fluorine implantation under NBTI (Negative bias temperature instability) stress. The fluorinated TFTs' devices can obtain better characteristics with samller threshold voltage shift, lower trap states and lower subthreshold swing variation. Therefore, the fluorine implantation does not only improve initial electrical characteristics, but also suppresses the NBTI-induced degradation.


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