Scanning electron beams

Scanning electron beam systems are available commercially, and are commonly used for mask generation. Electron projection systems are also used to obtain resolution over a large field. Current cathode sources have a short lifetime, limiting use in production processes. 

Figure 26. Three-dimensional electron scattering model for a resist on a thick substrate with a scanning electron beam of zero diameter.

Figure 21. Scanning electron beam micrographs of COP negative electron resist patterns developed in two different ketone-alcohol mixtures.

Figure 22. Scanning electron beam micrographs of a typical negative resist developed in different solvents. The dose was similar in both cases.

Radiation cross-linking of polyethylene requires considerably less overall energy and less space, and is faster, more efficient, and environmentally more acceptable. Chemically cross-linked PE contains chemicals, which are by-products of the curing system. These often have adverse effects on the dielectric properties and, in some cases, are simply not acceptable. The disadvantage of electron beam cross-linking is a more or less nonuniform dose distribution. This can happen particularly in thicker objects due to intrinsic dose-depth profiles of electron beams. Another problem can be a nonuniformity of rotation of cylindrical objects as they traverse a scanned electron beam. However, the mechanical properties often depend on the mean cross-link density. ... 

The most obvious way to improve throughput in scanning electron beam systems is to combine a variable shaped beam column, with a continuously moving table. The shaped beam ensures maximum beam current, and the continuously moving table potentially eliminates many overhead times. Registration can be accomplished without stopping the table, either by means of a laser interferometer, or through direct beam to sample reference. 

Petroff and Lang (1977) combined DLTS with scanning electron microscopy in a method that allows spatial imaging of deep states in the plane of a junction. The scanned electron beam is pulsed on and off and the resulting thermally stimulated current or capacitance transient is analyzed using the usual DLTS methods. 

In the direct method, an X-ray-sensitive vidienn TV camera direedy converts the X-ray image into an electronic charge pattern on a photoconductive target, which is read out by a scanning electron beam and displayed visually on a TV monitor. 

For calibrating the accelerator, poly(vinyl chloride) films and a simple water calorimeter are used in addition to monitoring and controlling the electrical parameters of the accelerator which affect the dose output and, in turn, the absorbed dose. The poly(vinyl chloride) is used primarily for establishing the depth dose in samples irradiated with the scanned electron beam. This film is relatively thin when compared with the range of 10... 

In contrast to the image dissector, which measures the photon flux, the vidicon is an integrating device, where the target serves as a memory buffer, storing information until the scanning electron beam reads and erases it. 

Fig. 14. Scanning Auger electron micrograph of a pattern in a-Si H previously irradiated by an interrupted scanning electron beam. [After Schade and Hockings (1983).]...

Exposing a predesigned pattern in the resist with a scanning electron beam (step 3). 

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