Robert Otto Schwenker

Arsenic Clustering in Silicon

Large decreases in the conductivity of arsenic‐doped silicon have been observed during 500–970°C heat treatments. The rate of conductivity change depends upon the prior quenching rate from diffusion temperature to room temperature. These conductivity changes are reversed by higher‐temperature treatments. The relationship between the electrically active arsenic, as calculated from the conductivity, and the total arsenic is shown to be consistent with a model of substitutional arsenic atoms being nonionized when in a cluster or in a complex involving one or more vacancies.

Dislocation propagation and emitter edge defects in silicon wafers

Some transistor defects show a tendency to occur near the edges of emitters. Like ’’area defects’’, these ’’edge defects’’ occur in silicon wafers in a distribution pattern reminiscent of thermal‐stress‐induced dislocations. A peculiar feature is that often a number of edge defects which are close replicas of one another occur in a string, each in one of the neighboring emitters. Such edge defects are preponderant in transistors having silicon nitride surface films. In our proposed model, these emitter edge defects are generated when thermal‐stress‐induced dislocations glide through a row of emitters and interact with the emitter edge stresses, thereby, and under appropriate conditions, casting off small dislocation half‐loops which straddle the edges. The model is shown to be consistent with all the observed phenomena pertaining to the emitter edge defect. To provide a foundation for the discussion of the finer details of the emitter edge defects, we also present an analysis of the nature and distributio...

Effects of ion implantation on substrate hardening and film stress reduction and their effect on the yield of bipolar transistors

We report evidence of the occurrence, and some salient features, of two phenomena arising from ion implantation of silicon: one is a hardening effect of the silicon substrate; the other is a stress‐reduction effect in silicon nitride films. The method of indentation dislocation rosettes (IDR) was the tool used for this study. The ion species investigated included boron, arsenic, argon, oxygen, and nitrogen, as well as oxygen from recoil implantation by arsenic into a film of thermal SiO2. Arsenic is the least effective among the ions studied, producing an ∼70% increase in the critical stress‐of‐dislocation movement (τc), whereas boron brought about an order‐of‐magnitude increase in τc. Other ions are comparable to boron. A plausible explanation is that the 1×1016 ions/cm2 boron implantation at room temperature was below the critical dose for silicon amorphization (∼2×1016 ions/cm2), so that rapid defect annealing via epitaxial regrowth could not occur, leaving much residual damage. The arsenic implantatio...

Diffusion of arsenic along dislocations in epitaxial silicon films

Abstract 76 As isotope has been diffused along stair rod dislocations associated with stacking faults in Si epitaxial layers. Diffusions were performed in a two-temperature zone furnace using neutron-activated elemental As as the diffusion source. Uniform densities of dislocations (>10 6 /cm 2 ), with axes intercepting the diffusion surface, were obtained following the growth of epitaxial layers on Si substrates whose surfaces were damaged by ion implantation to high dosages. Sections were taken by an anodizing and stripping technique and their activity was determined by liquid scintillation methods. The resulting profiles revealed a composite shape indicative of normal lattice diffusion near the surface together with a deeply penetrating portion which can be unambiguously associated with rapid diffusion along dislocations. For temperatures in the range 950°–1050°C, the intrinsic diffusivity of As in the lattice is given by D i =(0.51 +0.19 −0.14 cm 2 / sec ) exp (3.53±0.03 eV / kT ) and for the dislocations KδD d =((9.4±1.6) x 10 −8 cm 3 / sec ) exp (2.56±0.02 eV /kT)

Design tradeoffs for beyond 20 Gb/in.2: Using a merged notched head on advanced low noise media (invited)

Design considerations for areal densities beyond 20 Gb/in.2 are discussed, and in particular a demonstration at 24.8 Gb/in.2 is shown. The demonstrations used a single combined write and read head (Merge, Notched head). In this article we will discuss the tradeoffs in kilobytes per inch (KBPI) and tracks-per-inch in obtaining areal densities at 25 Gb/in.2 densities. The KBPI is limited by both the total signal-to-noise ratio and the nonlinear-transition shift. Simple estimates of the increase in channel performance from class IV partial response (PR4), extended partial response 4 (EPR4), and modified EEPR4, as well as the addition of codes which eliminate bit shift and tribit errors are discussed as large contributors to the increase in the areal density.

Effects of conductor passivation on bubble propagation in contiguous disk devices

The present work investigated the impact of conductor passivation on 1 μm bubble propagation in contiguous disk devices. Without conductor passivation, devices with overlying AlCu stripes showed good propagation margins. When the devices were passivated with a thick layer of SiO2, the elastically ’’hard’’ dielectric material imposes a constraint to AlCu deformation and increases the conductor edge force. Furthermore, the edge force of the SiO2 passivation at the conductor edges, being in the same sign as that of the AlCu stripe, contributes to the total force acting on the underlying garnet. This intensifies the lcoal stress fields in the magnetic devices and seriously reduces the bubble propagation margin. To alleviate this passivation‐enhanced stress problem, contiguous disk devices were passivated by elastically ’’soft’’ polyimide instead of sputtered SiO2.