Eisuke Mitani

MeV-energy B+, P+ and As+ ion implantation into Si

Abstract Annealing behavior of secondary defects in 2 MeV B + and P + , and 1 MeV As + ion implanted (100) Si has been investigated in terms of their structure, nature and depth distribution. This is done mainly through cross-sectional TEM observations at doses of 2 × 10 13 , 1 × 10 14 and 5 × 10 14 ions/cm 2 . The critical dose for generating secondary defects is between 2 × 10 13 and 1 × 10 14 ions/cm 2 , independent of ion species. A characteristic of B + and P + ion implanted layers is that buried secondary defects are formed beneath the substrate surface, with their maximum densities at depths of around 3.2 μm (B) and 2.1 μm (P) below the surface. These defect peak positions in the crystal are constant under all annealing conditions (e.g., a temperature range of 700 to 1250°C, annealing time of up to 6780 min at 1000°C). In contrast, the defects in the layers implanted with As + ions have an almost constant density in their depth distribution and change their depth position with annealing time and temperature. The peaks (B and P) and the central position (As) of these secondary defects are positioned deeper than both the projected range and the primary defect peak of each ion species.

Depth distribution of secondary defects in 2‐MeV boron‐implanted silicon

Annealing behavior of secondary defects in 2‐MeV boron ion‐implanted (100) silicon has been investigated mainly through cross‐sectional TEM observations. The maximum defect density is located at a mean depth of 3.2 μm from the surface and the location is 0.3 μm deeper than that of the projected range of boron ions. This defect position in the crystal is constant under all annealing conditions (e.g., a temperature range of between 700 and 1000 °C, annealing time of up to 6780 min at 1000 °C), although the vertical distribution width of defects changes with both annealing temperature and time.

An 18O study of oxygen exchange phenomena during microwave‐discharge plasma oxidation of silicon

The mechanism of oxygen migration during microwave‐discharge plasma oxidation of Si is investigated using secondary ion mass spectroscopy depth‐profile analysis and 18O as a tracer. The exchange phenomenon between migrating oxygen and its counterpart in SiO2 is observed. When the plasma‐grown oxide (Si16O2) is reoxidized in 18O plasma, the 18O is observed both at the Si/SiO2 interface and in the bulk of the Si16O2. In a reverse example, when Si18O2 is reoxidized in 16O plasma, the total amount of pre‐existing 18O in Si18O2 decreases. The suppression of 18O is more distinct near the surface region. These oxygen distributions indicate that oxygen migrates toward the interface accompanied by oxygen exchange. Since the exchange phenomenon is not observed in dry thermal oxidation, in which oxygen molecules migrate, active oxygen atoms or atom ions should induce the exchange by breaking the Si–O bond during migration.

Determination of traces of boron in semiconductor amorphous silicon film by filament-vaporization inductively-coupled plasma/atomic emission spectrometry

Abstract Silicon is dissolved from the platinum substrate by nitric/hydrofluoric acids. The recovery of boron on direct analysis was poor, but was increased to >95% by the addition of 500–5000 μg ml −1 phosphorus as phosphoric acid. The results compared well with the molar ratio of the gases (B 2 H 6 /(Ar + H 2 ) used to form the film and the intensity ratio of 11 B + and 30 Si + obtained by secondary-ion mass spectrometry.

Oxygen Exchange Phenomena in SIO2 During Microwave-Discharge Plasma Oxidation

The oxygen migration process during microwave-discharge plasma oxidation of Si is investigated using 18 O as a tracer. The exchange phenomena between migrating oxygen and its counterpart in SiO 2 are observed. When plasma grown oxide (Si 18 O 2 ) is further oxidized in 18 O-enriched plasma. 18 O is observed both at the SiO 2 /Si interface and in the bulk of Si 16 O 2 . For the reversed case. i.e. Si 18 O 2 is oxidized in 18 O plasma, the total amount of pre-existing 18 O decreases. The suppression of 18 O is more drastic in the surface region. These oxygen distributions indicate that oxygen migrates toward the interface accompanied by oxygen exchange.

Display device for ion beam profile

A display device for ion beam profiles which permits the study of mass spectrometer ion source performance is presented. In this device the ion beam from the source is deflected by two pairs of plate electrodes, and a small portion of the beam’s cross section is directed through a 50‐μm aperture. Thus, the sampling spot of the beam’s cross section is scanned as in a TV. The analog signal of the detected ion current is fed into an equistrength signal generator and converted into pulses, which are used to modify the brightness of a CRT. At the same time, the flying spot on the CRT is synchronized with the ion beam scanning. Thus, the intensity distribution of the beam’s cross section is displayed as equistrength lines on the CRT.