Julius Hållstedt

Application of high-resolution x-ray diffraction for detecting defects in SiGe(C) materials

The application of high-resolution x-ray diffraction for detecting and distinguishing defects in SiGe(C) layers is presented. A depth profile of the defects in SiGe/Si multilayers has been performed by using high-resolution reciprocal lattice mapping at different asymmetric reflections. Transmission electron microscopy was also applied in order to observe defects in the layers and these results were linked with the x-ray analysis. The substitutional C or B concentration in SiGe was measured by the shift of layer peak compared to the intrinsic layers. The thermal stability of the SiGe layers was investigated in order to rank the epitaxial quality of the SiGe below the detection limit of x-ray technique. It has also been demonstrated that x-ray analysis can be used for in-line process monitoring of layers grown in small device openings on patterned substrates. These types of analysis have also been used routinely for the evaluation of processed samples.

The effect of carbon and germanium on phase transformation of nickel on Si1−x−yGexCy epitaxial layers

The influence of carbon and germanium on phase transformation and sheet resistance of Ni on epitaxially grown Si1−x−yGexCy (0⩽x⩽0.24 and 0⩽y⩽0.01) layers annealed in a temperature range of 360 to 900 °C has been investigated. The role of strain relaxation or compensation in the reaction of Ni on Si1−x−yGexCy layers due to Ge or C out-diffusion to the underlying layer during the phase transformation has also been investigated. The formed NiSiGe layers were crystalline, with strong (020)/(013) growth orientation in the direction, but the thermal stability decreased rapidly with increasing Ge amount due to agglomeration. However, this thermal behavior was shifted to higher annealing temperatures when carbon was incorporated in the SiGe layers. A carbon accumulation at the interface of NiSiGeC/SiGeC has been observed even at low-temperature annealing, which is suggested to retard the phase transformation and agglomeration of Ni/SiGeC system.

Comprehensive Evaluation and Study of Pattern Dependency Behavior in Selective Epitaxial Growth of B-Doped SiGe Layers

The influence of chip layout and architecture on the pattern dependency of selective epitaxy of B-doped SiGe layers has been studied. The variations of Ge-, B-content, and growth rate have been investigated locally within a wafer and globally from wafer to wafer. The results are described by the gas depletion theory. Methods to control the variation of layer profile are suggested.

Pattern dependency in selective epitaxy of B-doped SiGe layers for advanced metal oxide semiconductor field effect transistors

This study presents investigations about the physical mechanisms, origin, and methods to control the pattern dependency in selective epitaxial growth of Si1-xGex (x=0.14-0.32) layers. It is shown ...

Design and analysis of efficient and compact antenna for paper based UHF RFID tags

Paper substrate is one of the paramount nominees for radio frequency identification (RFID) tags but at the same time it is extremely prone towards environmental changes. In this paper, antennas for UHF RFID tags on paper based substrate are investigated and analyzed for the first time to evaluate the effect of change in dielectric constant on the antenna parameters and performance. On the basis of analysis a concrete meander line antenna is proposed, designed and evaluated which has tremendous immunity towards variation in dielectric constant.

Development and experimental verification of analytical models for printable interdigital capacitor sensors on paperboard

Printed interdigital capacitor (IDC) on paperboard is a promising solution for low-cost sensors in intelligent packaging applications. The currently available analytical models of multi-layered IDCs are targeted to those fabricated by conventional semiconductor process. For this reason, we have adapted two promising models and assessed their accuracies by comparison with experimental data. We modified these models by treating the paper as non-infinite thick substrate and taking the effect of printed metal thickness into account. The models are studied further to reveal the relationship between the response of capacitance change and various geometric parameters which enables a quick way of obtaining the optimum IDC structure design. The modified Gevorgian model fits our experimental data best, and the sensitivity of IDCs is largely affected by its spatial wavelength and the thickness of sensing material layer, while the finger number, length and metallization ratio have minor impact.

Hole mobility in ultrathin body SOI pMOSFETs with SiGe or SiGeC channels

The hole mobilities of SiGe and SiGeC channel pMOSFETs fabricated on ultrathin silicon-on-insulator substrates are investigated and compared with reference Si channel devices. The total thickness of the fully depleted Si/SiGe(C)/Si body structure is /spl sim/ 25 nm. All devices demonstrated a near ideal subthreshold behavior, and the drive current and mobility were increased with more than 60% for SiGe and SiGeC channels. When comparing SIMOX and UNIBOND substrates, no significant difference could be detected.

Selective Epitaxial Growth with Full Control of Pattern Dependency Behavior for pMOSFET Structures

This study presents a way to design chips to obtain uniform selective epitaxial growth of SiGe layers in p-type metal-oxide-semiconductor field-effect transistor (pMOSFET) structures. The pattern d ...

Low‐frequency Noise in SiGe Channel pMOSFETs on Ultra‐Thin Body SOI with Ni‐Silicided Source/Drain

The low‐frequency noise in buried SiGe channel pMOSFETs fabricated on ultra‐thin body silicon‐on‐insulator (SOI) substrates is investigated. The total thickness of the Si/SiGe/Si body structure, which is fully depleted (FD), is 20 nm. The low‐frequency noise properties are compared with FD SOI pMOSFETs with a 20 nm Si body. The effect of the Ni‐silicide used in the Source/Drain were also studied, especially the case of Schottky‐Barrier (SB) MOSFETs when the Ni‐silicide is formed at the edges of the channel.

Influence of a Si layer intercalated between Si0.75Ge0.25 and Ni on the behavior of the resulting NiSi1−uGeu film

The interaction of Ni films with epitaxially grown Si-capped and not capped Si0.75Ge0.25 layers on Si(100) at 500°C leads to the formation of NiSi1−uGeu films as a bilayer NiSi on NiSi0.75Ge0.25 with a rather clear compositional boundary. In the absence of a Si cap at the surface, NiSi0.75Ge0.25 is formed on NiSi. Epitaxy of NiSi on NiSi0.75Ge0.25, and vice versa, occurs across the compositional boundary. The crystallographic orientation of the NiSi1−uGeu films is strongly affected by the initial layer thicknesses and the layer sequence. Without a Si cap, the NiSi1−uGeu films show an increased fiber texture with increasing Si0.75Ge0.25 thickness. In the presence of a Si cap, on the other hand, the texture collapses into a random orientation already for thin caps. Rapid diffusion of Ge at 500°C results in the presence of some Ge at the NiSi∕Si interface for a NiSi0.75Ge0.25∕NiSi∕Si structure. This diffusion is accompanied by an increased roughness at the NiSi∕Si interface, as compared to the quite flat NiS...