Mahdi Moeen

Optimization of SiGe selective epitaxy for source/drain engineering in 22 nm node complementary metal-oxide semiconductor (CMOS)

SiGe has been widely used for source/drain (S/D) engineering in pMOSFETs to enhance channel mobility. In this study, selective Si1−xGex growth (0.25 ≤ x ≤ 0.35) with boron concentration of 1–3 × 1020 cm−3 in the process for 22 nm node complementary metal-oxide semiconductor (CMOS) has been investigated and optimized. The growth parameters were carefully tuned to achieve deposition of high quality and highly strained material. The thermal budget was decreased to 800 °C to suppress dopant diffusion, to minimize Si loss in S/D recesses, and to preserve the S/D recess shape. Two layers of Si1−xGex were deposited: a bottom layer with high Ge content (x = 0.35) which filled the recess and a cap layer with low Ge content (x = 0.25) which was elevated in the S/D regions. The elevated SiGe cap layer was intended to be consumed during the Ni-silicidation process in order to avoid strain reduction in the channel region arising from strain relaxation in SiGe S/D. In this study, a kinetic gas model was also applied to...

Single crystal diamond for infrared sensing applications

The synthesis of new materials for thermal infrared (IR) detection has been an intensive research area in recent years. Among new semiconductor materials, synthetic diamond has the ability to function even under very high temperature and high radiation conditions. In the present work, diamond Schottky diodes with boron concentrations in the range of 1014 < B < 1017 cm−3 are presented as candidates for IR thermal sensors with an excellent temperature coefficient of resistance (−8.42%/K) and very low noise levels around 6.6 × 10−15 V2/Hz. This enables huge performance enhancements for a wide variety of systems, e.g., automotive and space applications.

Impact of pattern dependency of SiGe layers grown selectively in source/drain on the performance of 22 nm node pMOSFETs

Pattern dependency of selective epitaxy of Si1 xGex (0.20 6 x 6 0.45) grown in recessed source/drain regions of 22 nm pMOSFETs has been studied. A complete substrate mapping over 200 mm wafers was performed and the transistors’ characteristics were measured. The designed SiGe profile included a layer with Ge content of 40% at the bottom of recess (40 nm) and capped with 20% Ge as a sacrificial layer (20 nm) for silicide formation. The induced strain in the channel was simulated before and after silicidation. The variation of strain was localized and its effect on the transistors’ performance was determined. The chips had a variety of SiGe profile depending on their distance (closest, intermediate and central) from the edge of the 200 mm wafer. SiGe layers with poor epi-quality were observed when the coverage of exposed Si of the chip was below 1%. This causes high Ge contents with layer thicknesses above the

Characterization of SiGe/Si multi-quantum wells for infrared sensing

SiGe epitaxial layers are integrated as an active part in thermal detectors. To improve their performance, deeper understanding of design parameters, such as thickness, well periodicity, quality, and strain amount, of the layers/interfaces is required. Oxygen (2–2500 × 10−9 Torr) was exposed prior or during epitaxy of SiGe/Si multilayers. In this range, samples with 10 nTorr oxygen were processed to investigate layer quality and noise measurements. Temperature coefficient of resistance was also measured to evaluate the thermal response. These results demonstrate sensitivity of SiGe-based devices to size and location of defects in the structure.

Combined Si Schottky barriers and SiGe/Si multi quantum wells for infrared detection

Un-cooled bolometer arrays have been considered as good choices for detection of infrared waves in the ranges of 3–5μm (MWIR: mid wavelength infrared) and 8–12μm (LWIR: long wavelength infrared). Advantages are found in their relative simplicity of mechanism and design, hence, fabrication cost, when compared to detectors working based on photon detection mechanisms. A temperature dependent resistor (or thermistor) is the core element of a bolometer. The rate of resistance dependency to temperature is a figure-of-merit for thermistor material, acting as the active element in a bolometer. This property is characterized by temperature coefficient of resistance (TCR). At the same time, for the better IR detection and imaging quality, high signal-to-noise ratio (SNR) is also sought. Different materials have been proposed and/or implemented commercially to work as thermistor materials. Among them are VOx, amorphous silicon, amorphous and poly SiGe.