C.J. Vriezema

On some factors limiting depth resolution during SIMS profiling

Abstract The claim that the systematics observed in high-energy ion-beam-mixing experiments applies equally well to broadening observed in low-energy sputter depth profiling studies is addressed. Taking the expression for energetic mixing derived by the Caltech group at face value, it is shown that under fairly general assumptions this can be cast into a more tractable analytical formula. Essentially the final result reads that the broadening at low impact energy E is proportional to E 1 2 cos ϑ for not too glancing angles of incidence (ϑ

An effective barrier against the interdiffusion of iron and zinc dopants in InP

The diffusion of iron and zinc in InP is studied with secondary‐ion mass spectrometry (SIMS). Intentionally doped metalorganic‐vapor‐phase‐epitaxy‐ (MOVPE‐) grown layers as well as ion‐implanted samples were investigated. In addition, resistivity measurements were performed on MOVPE‐grown, iron‐doped InP layers. The diffusion behavior of iron is strongly influenced by the presence of zinc and vice versa. In adjacent regions of iron and zinc‐doped layers of InP there is a dramatic interdiffusion of both dopants. The interdiffusion process can be described with a kick‐out mechanism in which iron interstitials kick out substitutional zinc. The diffusion of the iron interstitials is an extremely fast transport process in InP, but the concentration of iron interstitials remains below 5×1014 at cm−3. Due to this fast transport, the interdiffusion process proceeds even through barrier layers of (undoped) InP, while in the barrier layer itself the iron concentration remains below the SIMS detection limit (<5×1014...

Oxygen bleed-in during SIMS depth profiling: curse or blessing?

Abstract Oxygen flooding of the target during SIMS depth profiling finds widespread application foranumber of reasons. Among others it enhances the (positive) secondary ionization efficiency, helps in suppressing bombardment-induced surface topography development and reduces the transition time to steady-state erosion conditions. These attractive properties are offset by a number of artefacts that may be introduced by O2 inlet. A summary of vices and virtues, largely based on existing knowledge, is presented. Then one of the few open questions is addressed, namely to what extent O2 bleed-in ffects depth resolution. This is examined in some detail by studying ultrashallow dopant profiles of B, P, Ga or Sb in Si by SIMS with and without O2 leak.

Heterojunction bipolar transistors with Si1−xGex base

Mesa-isolated bipolar transistors with strained Si1-xGez-base layers, grown by molecular beam epitaxy end atmospheric pressure chemical vapour deposition, have been fabricated. Results of structural and electrical analysis of transistors with implanted emitters and with phosphorus and arsenic-doped polysilicon emitters are presented.

Isotopical ranges: 10,11B ion implantation in Si

Abstract SIMS depth profiling has been done on Si targets implanted with both 10 B and 11 ions at the same energy of 25 keV, 75 keV, 170 keV or 400 keV. Relative projected range differences could be determined with high accuracy. It was found that the projected range of 11 B exceeds that of 10 B and more pronounced so with higher energy. This observation is in broad agreement with the analytical theory, although a detailed comparison reveals minor but highly significant discrepancies. Consequences for the results of recently published NRA data on boron ranges in silicon will be discussed.

Co diffusion and precipitation in Si/SiGe heterostructures

Several Si/Si1−xGex multilayer structures, grown by molecular‐beam epitaxy (MBE) or synthesized by high‐dose Ge implantation into Si substrates, have been implanted with Co atoms at doses of typically 1.0×1015 and 1.0×1016 ions/cm2. These samples are annealed at elevated temperatures (typically 850 °C) to study the diffusion and precipitation of the Co atoms. Depth distributions of Co atoms are measured with secondary‐ion mass spectrometry. X‐ray diffraction is used to measure the strain evolution of the Si/Si1−xGex MBE multilayers during processing. Channeling Rutherford backscattering spectrometry is used to study the lattice position of the Co atoms after heat treatment. Upon annealing, Co atoms are observed to diffuse out of the Si1−xGex layers. The efficiency of this outdiffusion process strongly depends on the implantation dose. The released Co atoms are gettered by the Si layers adjacent to the Si1−xGex layers and, in case of the MBE samples, at the interface between the substrate and MBE‐grown buf...

Tilted angle implantations of B, Al and Ga in single crystalline Si

Abstract Boron, aluminium and gallium ions were implanted at 600 keV in a crystalline Si-(001) target for tilt angles 11.6 °, 33.7 °, 63 °, 73 ° and 83 °. The depth profiles of the implanted impurities were measured with secondary ion mass spectrometry. These experimental data are compared with simulated impurity distributions from the Monte Carlo code MARLOWE (version 12). Projected range, lateral and longitudinal spread are discussed.