Browse Prior Art Database

Large Field E-Beam Spot Shape Measurement Technique

IP.com Disclosure Number: IPCOM000050309D
Original Publication Date: 1982-Oct-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Golladay, SD: AUTHOR [+3]

Abstract

A Faraday cup arrangement is employed, under the scanning cross-wires used for periodic E-beam inspection tool calibration, to aid in capturing all the electrons which bypass the cross-wires.

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Large Field E-Beam Spot Shape Measurement Technique

A Faraday cup arrangement is employed, under the scanning cross-wires used for periodic E-beam inspection tool calibration, to aid in capturing all the electrons which bypass the cross-wires.

In E-beam systems, it is important to know the size, shape and current density of the beam over all positions of the addressable field. In particular, for multilayer ceramic (MLC) inspection tool applications where the field size is in the order of 10 x 10 cm, a real time continuous display of the spot shape is required so that proper dynamic corrections may be applied.

In this regard, the technique of scanning cross-wires (or other sharp edges) in the X and Y directions and then differentiating the signal collected below the wires (or backscattered from the target) provides good results when operating at high beam energies (for example, greater than 5 KV) and small deflection angles. On the other hand, in MLC testing, the E-beam operates at approximately 1.5 KV which, for many materials (including Cu, Al and brass commonly used in target construction) is near the unity secondary electron emission point. Consequently, at this E-beam accelerating potential the net signal collected is zero or, at very best, noisy.

In order to capture all electrons which bypass the cross-wires, a Faraday cup configuration may be employed under each wire crossing where the orthogonal X-Y L-scan is performed. Fig. 1 shows the basic prior art cro...