Automatic measurement of scanning beam diameter using an on‐line digital computer

Abstract

A method for the measurement of electron probe beam diameter by digital image processing has recently been published. The purpose of the present report is to describe the development of an automatic system for beam diameter measurement. To complete this system, a method based on a theory which combines automation and high-resolution conditions is proposed. In practice, the beam diameter is measured from the STEM image of a crystalline hole in a gold thin film, utilizing an on-line computer system equipped with newly developed digital processing programs linked to a SEM in the transmission mode. The functions of the programs include statistical processing, matching, noise removal, interpolation, selection, and rotation. By combining these functions, the scanning beam diameter is accurately measured, in spite of difficulties, under most electron microscope operating conditions. The user simply appoints the edge included in the STEM image.

Measurement of the parameters of the electron beam of a scanning electron microscope

“…In Ref. [5], parameter r 3 is used as the radius of the electron probe (see expression (4)), which characterizes the Gaussian form of the electron distribution. Then the size (diameter) of the beam is 3 GDED 2r d = .…”

“…(1). As a first approximation (see expression (5)) this solution can be obtained by performing the differentiation of the SEM signal. This idea was tested on a low-voltage SEM, which is a part of an electron optical metrology system (EOMS, PTB, Germany) for the electron beam energy E = 1 keV.…”

“…At present there are a few methods to measure the electron beam diameter [3][4][5]. However, these methods are not widely used.…”

The conversion of a field‐emission scanning electron microscope to a high‐resolution, high‐performance scanning transmission electron microscope, while maintaining original functions

“…The details of the computer system have been described elsewhere (Oho et al, 1986a). In addition, an off-line digital image processing system used for filtering the CTEM image has been reported by Kanaya et al (1982a,b).…”

“…The computer system utilized in the present paper consisted of an analogue-to-digital converter (1,024 x 1 x 8 bit), microcomputer (CPU 6800, LSI-ll), image memory (1,024 x 1,024 x 8 bit; 1 frame, 512 x 512 x 8 bit; 16 frames), black and white video monitor and color monitor (512 x 512 x 8 bit), hard and floppy disk, and magnetic tape. The details of the computer system have been described elsewhere (Oho et al, 1986a). In addition, an off-line digital image processing system used for filtering the CTEM image has been reported by Kanaya et al (1982a,b).…”