Hiroyuki Shinada

Tungsten Schottky emitters with reservoirs of metal oxide or nitride

Abstract To obtain highly stable electron emission with a narrow energy width, we have investigated the electron emission characteristics of tungsten Schottky emitters made with various reservoir materials. The work functions of the adsorbed layers were calculated by using a simple electric dipole model, and we found that M1/O/W (M1=Sc, V, Y, Nb or La) and M2/N/W (M2=Ti, V, Y, Zr, Nb or La) compositions were expected to have a lower work function than that of the conventional Zr/O/W Schottky emitter. We formed M1/O/W and M2/N/W Schottky emitters and measured their electron emission properties. The Sc/O/W, Nb/O/W, and Y/N/W Schottky emitters produced a continuous and confined electron beam at tip temperatures below 1800 K of the Zr/O/W Schottky emitter, and the energy widths of their Schottky-emitted electrons were equal to or narrower than the 0.4 eV of the Zr/O/W Schottky emitter. The Sc/O/W Schottky emitter had the narrowest width at 0.25 eV.

Aberration corrected 1.2-MV cold field-emission transmission electron microscope with a sub-50-pm resolution

Atomic-resolution electromagnetic field observation is critical to the development of advanced materials and to the unveiling of their fundamental physics. For this purpose, a spherical-aberration corrected 1.2-MV cold field-emission transmission electron microscope has been developed. The microscope has the following superior properties: stabilized accelerating voltage, minimized electrical and mechanical fluctuation, and coherent electron emission. These properties have enabled to obtain 43-pm information transfer. On the bases of these performances, a 43-pm resolution has been obtained by correcting lens aberrations up to the third order. Observations of GaN [411] thin crystal showed a projected atomic locations with a separation of 44 pm.

Dynamic micromagnetic field measurement by stroboscopic electron beam tomography

A stroboscopic electron beam tomography system for measuring the dynamic micromagnetic field of recording heads is presented. A pulsed electron beam, which is synchronized with the recording head driver, is scanned along the recording head surface from all directions. Integration of the magnetic field intensity along the beam path is calculated from the electron beam deflection angle. Intensity distributions of the dynamic magnetic field are calculated using a tomographic reconstruction algorithm. To obtain enough current even in pulsed electron beam operation, a high-brightness Ti/W thermal field emitter is used. This system was successfully applied in measuring the field distributions of a thin-film recording head, with 0.1 mu m spatial resolution and 1 ns time resolution at an operation frequency of 30 MHz. >

New voltage-contrast imaging method for detection of electrical failures

A new voltage contrast imaging method using single scan of high current electron beam has been developed. This method achieved the automatic inspection system, which detects electrical failures in acceptable amount of time. The sensitivity of the system is evaluated using open failure of via holes. First, the image contrast of poly-Si deposited on defective via holes is measured. Then the cross section of the defects is examined to obtain the correlation between contrast and the thickness of resistive residue at the bottom of the defective via holes. The result shows that this imaging method is capable of detecting 2 nm oxide remaining at the bottom of via.

Time resolved measurement of dynamic micro-magnetic field by stroboscopic electron beam tomography

Stroboscopic electron-beam tomography has been achieved for time-resolved measurement of the magnetic recording thin-film head. The transition characteristics of magnetic field distributions were compared; the driving current was found to have a temporal resolution of 1 ns. Both the driving current waveforms and the magnetic field distributions are measured by a pulsed electron beam with the same timing pulse gate. This measurement was successfully applied to Ni-Fe and CoTaZr amorphous thin-film disk heads. It was found that the magnetic field distribution change with time is not uniform and that the peak field is a few nanoseconds behind the driving current for Ni-Fe heads. The frequency characteristics of these heads correspond for the magnetic field delay to the driving current. The frequency characteristics of the head whose magnetic field delay is longer are inferior to those of the head whose magnetic field delay is shorter. >

Multi-sampling method in an EBT for logic waveform measurement

Abstract A multi-sampling method is applied to logic waveform measurement. In this method, a number of pulses are generated in one logic cycle; these pulses are synchronized with the device clock. It offers a rise-time resolution as high as that of the stroboscopic method and a measurement time shorter than that of the stroboscopic method by a factor equal to the number of pulses generated in the logic cycle. A developed SE detector with an 8ns response time is able to measure a logic waveform with a 50MHz clock rate and 100k clock cycles within a measurement time of 100 seconds which is 1/100,000 as that by a stroboscopic method.

Observation of Magnetic Head Fields Using Distorted Transmission Electron Microscopy Images

We have observed magnetic fields generated from a thin film magnetic head using transmission electron microscopy (TEM) images. The image in which the shadow of the head appears together with the projected pattern of a reference film is acquired with the use of appropriate defocus. From the pattern distortion in the image, both strong and weak components of the head field can be detected. Furthermore, this method makes it possible to quantitatively analyze, with high spatial resolution, the magnetic field strength which depends on distance from the air bearing surface of the head.

E-beam fault diagnosis system for logic VLSIs

Abstract This paper describes the E-beam fault diagnosis system for logic VLSIs which is characterized by the capability of probing long sequential logical waveforms and by software tools on workstations supporting for guided probe diagnosis. The system was applied to analyzing a fault in the logic VLSI having 40Kgates. It took 4 days to identify the faults. The 4 days are a quarter of the term in case of using a conventional E-beam tester. Through modeling a block of combinational circuits, equations to evaluate the number of probing points are proposed. As the result, even in the 40Kgate logic VLSI, it is evaluated 202 at maximum which is considered as practical value.

A study on the field distribution of thin-film heads

The field distribution of a thin-film inductive head and its relationship to pole configurations are examined. Three components of the field distribution at high frequencies are measured using a newly developed electron beam tomography method. Focused ion beam etching is used for the processing of the pole configuration. A comparison between the measured field distribution and the results of three-dimensional computer simulation shows that a sharp field distribution suitable for high-density recording is produced to promote magnetization at the tip region. Furthermore, the optimum design of the pole configuration clarifies the feasibility of 1- mu m track recording. >

Resolution Assessment of an Aberration Corrected 1.2-MV Field Emission Transmission Electron Microscope

Observations of the structure and electromagnetic field at atomic resolution are critical for developing advanced materials. A lot of efforts are being made for achieving atomic resolution and for constantly improving it in transmission electron microscopes (TEMs) not only at the conventional in-lens specimen position (HR position) but also at a field-free specimen position (Lorentz position). In the last decade, 1/0.05 nm information transfer for 300-kV TEM has been demonstrated [1], and 0.5-nm resolution in Lorentz microscopy has been reported [2,3]. We developed an atomic-resolution holography electron microscope (1.2-MV TEM) equipped with a cold field-emission gun and a CEOS hexapole Cs-corrector. In this paper, we report on the resolution assessment of the developed 1.2-MV TEM. We found that the resolution reached 0.043 nm at the HR position and 0.24 nm at the Lorentz position.