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Temporary permissions are often granted for track use on peatlands. However, even when peatland track designs attempt to minimise environmental impacts via use of mesh systems, such linear disturbances may have persistent impacts. We evaluated the surface peatland structure of five abandoned tracks (four with a mesh surface, one unsurfaced) with varying past usage frequencies, at an upland site in northern England. Simplification of the surface nanotopography was found on all tracks compared to surrounding control areas, with increased micro-erosion patterns in rutted areas, and invasive species on some treatments. The frequency of previous usage was not found to be a significant factor controlling nano-topographic loss. Edge effects and hillslope position were influential in places, but these effects were not consistent across treatments. Nano-topographic recovery was found to be inhibited when track usage commenced within a short time frame after track construction. Mesh tracks appear to create a spatial constraint leading to poor development of plants and a reduced ability to form characteristic structures which are integral to mire function.

Background Older patients undergoing allogeneic stem cell transplant (SCT) have inferior outcomes. They have limited physiological reserves, which makes them more susceptible to toxic effects of conditioning regimens. Supportive care directed at maintaining and augmenting their limited functional reserve may reduce non-relapse mortality (NRM). We studied impact of a multidisciplinary supportive care and prehabilitation program (ER-SCT) and compared one-year NRM with a historical control group. Methods Between 1/1/15 and 9/30/18, 204 patients ≥ 65 years old underwent allogeneic SCT at our institution. ER-SCT program started on 10/1/17 and 57 of 64(89%) eligible patients participated during the first year. All 64 patients were included in the ER-SCT cohort, while patients treated between 1/1/15-9/30/17 were in the control group. ER-SCT program consisted of a prehabilitation phase prior to admission. Patients were evaluated by a multidisciplinary team consisting of a geriatrician, physical medicine and rehabilitation physician, physical therapist, occupation therapist, dietician, nurse, and a pharmacist specializing in SCT. Preexisting chronic conditions were optimized and recommendations were made for nutrition, exercise, and coping strategies. During hospitalization, fluid usage and medication choice / doses were optimized for older patients to prevent side effects such as fluid overload and delirium. Physical therapy, occupational therapy and nutrition counselling was continued. The team continued to follow and intervene as needed after discharge from the hospital. Results Median age was 68 (65-79) with 36 (18%) patients >than 70 years. Diagnoses included AML 96 (47%), MDS 57(28%), MPD 26 (13%), ALL 8(4%), and other 17 (8%). 103 (51%) had high or very high disease risk index (DRI). HCT-CI score was >3 in 80 (39%). Donor types included 127 (62%) matched unrelated, 57(28%) matched related and 20(10%) haploidentical. The NRM at 1 year was 13% in ER-SCT cohort vs 26% (p=0.03) in the control cohort. Multivariate analysis adjusting for GVHD prophylaxis and conditioning regimen, age, DRI, HCT-CI, donor type and graft source showed that ER-SCT HR=0.4 (0.2-0.9, P=0.02), comorbidity score Conclusion Although the data from this retrospective sequential cohort analysis cannot be conclusive, they do suggest that a multidisciplinary supportive care program (ER-SCT) may reduce NRM in older patients undergoing allogeneic SCT.

Material issues that impact the applicability of Ni based silicides to CMOS flows were studied, including the excessive silicidation of narrow features, the growth kinetics of Ni 2 Si and NiSi on single-crystalline and poly-crystalline silicon and the thermal degradation mechanisms. Ni 2 Si was found to grow by diffusion controlled kinetics with an activation energy of about 1.55 eV on single-crystalline Si. As a result, the excessive silicidation in small features can be reduced in a 2-step Ni-silicide process by reducing the thermal budget of the first RTP step. The mechanisms of thermal degradation of NiSi were studied. Thin NiSi films were found to degrade morphologically while still in the monosilicide phase. Thick NiSi films degrade morphologically at low temperatures and by transformation to NiSi 2 at high temperatures. The reaction of Ni with SiGe substrates and the effect of Ge on the thermal degradation of the Ni-germanosilicide were investigated. Activation energies for the thermal degradation of Ni(SiGe) on SiGe were found to be significantly smaller than the values found for the thermal degradation of NiSi on pure Si. The effect of alloying Ni with Pt or Ta was studied. NiSi films alloyed with Pt or Ta are found to be thermally more stable compared to pure NiSi. Alloying with Pt was found to improve the thermal stability of NiSi on narrow poly-Si gates. The kinetics of Ni 2 Si and NiSi formation on poly silicon were determined as well as their dependence on dopants. The presence of B in high doses was found to slow down the silicide formation significantly. Dopant segregation to the NiSi/oxide interface was observed, which is believed to be responsible for the observed shifts in work function. The sheet resistance of fully Ni-silicided 100 nm poly Si/oxide stacks is found to be stable up to 800 °C.

The reaction of Ni films with a Si"0"."8Ge"0"."2 alloy is studied in the temperature range of 200-750 ^oC from the point of view of process window, morphology of the resulting silicide, and mechanisms of degradation at high temperatures. The effect on the reaction of substrate crystallinity (single crystal and polycrystalline Si"0"."8Ge"0"."2), dopants (arsenic and boron) and process parameters is investigated. Sheet resistance measurements, X-ray diffraction and scanning electron microscopy were used for film characterization. Ni-rich germanosilicide is formed at low (

Excessive Ni-silicide formation is observed at the edges of poly gates and source/drain lines. The excessive silicidation results in locally completely silicided poly gates and in very high junction leakage in small source/drain islands. It was studied whether the excessive Ni-silicide formation in narrow features can be reduced in a two-step Ni-silicide process in which the thermal budget of the first RTP step is just enough to fully react the Ni. It was found that the excessive silicidation can be avoided either by reducing the anneal temperature or by reducing the anneal time. Reducing the thermal budget of the first RTP step was found to significantly improve the junction leakage in small source/drain islands for As junctions. No improvement was observed for B junctions. The latter is thought to be related to the presence of NiSi"2 pyramids.

Current techniques for definition of the junction recess suffer from degradation of the Si crystal quality. We demonstrate the suitability of in situ chemical vapour etching (CVE) by HCl as an alternative Si etch back technique. The process has been developed in a standard epitaxial growth system and allows Si thinning without defect creation and without contamination of the remaining Si surface. In situ combination of Si etch back with facet free selective epitaxial in situ doped SiGe re-growth, makes the technique very attractive. It is a suitable technology for the fabrication of ultra-shallow source/drain junctions. The replacement of Si by SiGe might be a possible route to reduce source/drain contact resistance.

The scaling behavior of Co, Co-Ni and Ni silicides to sub-40 nm gate length CMOS technologies with sub-100 nm junction depths was evaluated. Limitations were found for Co and Co-Ni alloy silicides, which exhibited an increase in sheet resistance at gate lengths below 40 nm and required high processing temperatures to achieve low junction leakage. Ni silicide was shown, in contrast, to have good scaling behavior, with a decrease in sheet resistance for decreasing gate lengths down to 30 nm, lower diode leakage (at similar sheet resistance) and lower silicide to p+ Si contact resistance than Co silicide. Key material issues impacting the applicability of NiSi to CMOS technologies were investigated. Studies of the kinetics of Ni2Si growth were used to design a process that avoids excessive silicidation of small features. The thermal degradation mechanisms of NiSi films were also studied. Thin films degraded morphologically with activation energies of ∼ 2.4 eV. Thick films degraded morphologically at low temperatures and by transformation to NiSi2 at high temperatures, suggesting a higher activation energy for the latter mechanism. Pt alloying was shown to help stabilize NiSi films against morphological degradation.

To get an insight in the diffusion behavior of boron after annealing and in particular its segregation characteristics towards the interface in oxide structures on silicon, it is necessary to probe the boron profile with very high accuracy and depth resolution. Sputter depth profiling as employed in secondary ion mass spectrometry (SIMS) is frequently used as the most suited tool for dopant profiling in view of its sensitivity and depth resolution. However, in order to determine the segregated boron peak, sub-nm depth resolution is required and artifacts such as beam induced broadening effects, potential ionization yield changes at interfaces, transient sputter yields need to be considered in detail. When reducing the primary beam energy the depth resolution can be improved and sub-nm depth sensitivity can be demonstrated. However, comparisons with high-resolution elastic recoil detection analysis demonstrate that even under those conditions no reliable depth profile can be obtained in the first nm near the surface nor even in the oxide part of the profile, where no ionization nor sputter yield transients are expected. Enhanced beam induced migration of boron during the initial phase of the bombardment needs to be invoked to explain the results.

As scaling progresses, conventional Co/Ti silicidation is facing difficulties related to the nucleation of the low resistive Co-disilicide phase during the second RTP step of silicidation. When linewidths, junction depths and silicide thicknesses are being reduced, the RTP2 thermal process window narrows down rapidly. It is expected that the process window can be widened by alloying the Co film with Ni, because the presence of Ni lowers the nucleation barrier for the Co-disilicide phase. Replacing Co-disilicide by Ni-monosilicide is a promising alternative because the same silicide sheet resistance can be obtained with 35% less silicon consumption.

CoSi2 formed using a Ti cap has been shown to reduce any oxide or contaminants present during silicide growth to improve the uniformity of the silicide. However, as transistor dimensions shrink, a concern in using CoSi2 is the thermal process window for the second RTP step (RTP2). Thinner silicides agglomerate at lower temperatures but a minimum temperature is required for a uniform silicide with low junction leakage. This paper describes the results of a detailed investigation into the thermal processing of thin Ti-capped CoSi2 compatible with 0.13 μm CMOS technology. Ti-capped CoSi2 films of varying thickness on both poly and active regions were studied for three junction dopants, As, BF2, and B. The parameters investigated in the thermal processing were the temperature, time and ramp rates for RTP2. Sheet resistance, diode leakage, and interface roughness were measured as a function of the thermal processing. The results show that the optimal RTP2 thermal budget for thin Ti-cap CoSi2 on devices is 800°C for 120 s with high ramp rates giving possible leakage improvement.

In this work, the phase formation is compared for Ni- and Co-silicidation with and without Ti cap. In addition, the electrical performance of Ni-silicidation with and without Ti-cap is investigated and compared to the performance of a Co-silicidation process with a Ti cap that has the same Si consumption. The lateral confinement of the silicide in the active areas is also studied.