Hitoshi Tsuyama

A stigmatic, second-order, double-focusing mass spectrometer

Abstract A double-focusing mass spectrometer of second order was constructed and the focusing property was examined. The ion optical system was determined by computer calculations in order to correct all second-order image aberrations. In the calculations the influences of the fringing field were taken into account. This ion optical system has velocity focusing, radial focusing and axial focusing properties. The instrument is composed of an electric toroidal sector ( r e = 212 mm, φ e = 85.2°, c = 0.5, ρ′ = −106 mm), and a uniform magnetic sector of non-zero entrance and exit angles ( r m = 200 mm, φ m = 90°, ϵ′ = 30°, ϵ″ = −10°). In experimental results, a maximum resolving power of 83 000 at 10% valley separation, and a total transmission of 43% were obtained. Axial focusing action and correction of the crescent shape resulting from second-order aberrations were observed from the shape of spectral lines taken on photographic plates.

Analyses of silicon wafers by a high-resolution secondary ion mass spectrometer

Abstract A high-resolution secondary ion mass spectrometer (SIMS) was constructed for solid surface analyses. The instrument is composed of a Hitachi IMA-2 ion probe and a stigmatic, second-order, double focusing mass spectrometer. Commercially available silicon wafers (p-type, 20 Ω cm) were analyzed as test samples. The highest mass resolving power was 11,000 (10% valley). The analytical sensitivity of this SIMS permits detection of boron to silicon at an ion ratio of 10 −7 . The inorganic and hydrocarbon element ions were accurately resolved.

Second-order image aberration correction of double-focusing mass spectrometers by electrostatic hexapole lens

Abstract Ion optical properties of an electrostatic hexapole lens are described. The correction methods for second-order image aberrations of double-focusing mass spectrometers are also examined. As an experimental example, the second-order image aberration of a Hitachi double-focusing mass spectrometer are observed, and reduced by the electrostatic hexapole lens of 40 mm length. It is confirmed by photographic plates that the second-order image aberration of curved image lines is corrected by this hexapole lens.

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.

Identification of Apparent Mass 80 Peak of Argon in Mass Spectrum Obtained with Static Operation

In the mass spectrum of argon obtained by a static operation, an abnormal peak appeared at the position corresponding to M/e=80. In order to identify whether this peak can be defined as diatomic ions Ar2+ or atomic ions Ar+2-1 produced by charge transfer, the yield curves were made as functions of the gas pressure, the ion energy and the electron energy. It was concluded from the curve obtained against electron energy that the ions are Ar2+ for electron energy below the appearance potential of Ar++ while above that energy, most of the ions are Ar+2-1 formed by the charge transfer process A+++Ar→Ar++Ar+ which occurred in the space between the ion source and the magnetic analyzer. This interpretation is in agreement with the observed shape of the peak at M/e=80.