<title>New submicron dimension reference for electron-beam metrology system</title>

Abstract

A novel submicron dimension reference for calibrating electron-beam metrology systems has been developed. A fine rectangular-profile diffraction grating fabricated by laser interferometer lithography and anisotropic chemical etching of (1 10) crystalline silicon satisfies any conditions for submicron dimension reference. In this reference, pitch size of about 0.2 im is easily obtained by laser interferometer lithography with an accuracy, shown by optical diffraction measurement, of within 1 nm. This reference also satisfies several requirements for electron-beam metrology systems. It is stable and free from build-up of charge under electron-beam irradiation because it is fabricated from a conductive silicon single crystal. Also it generates high-contrast secondary electron signals due to high-aspect ratio grating profile.Evaluation of this reference by optical diffraction measurement and electron-beam CD measurements show high performance for submicron dimension calibration. In electron-beam CD measurements, the deviation of repeated measurements is under 5 nm within 3.

Highly Accurate Grating Reference Fabricated by EB Cell Projection Lithography

“…CD-SEM (S-9260, Hitachi High-Technologies) was used for pitch size evaluation, which accuracy was within 1 nm after calibration using 240-nm pitch standard reference grating. 1,2) 3. Results and Discussions…”

“…For example, k ¼ 0:468 for 20 measurement points. Then the calibration accuracy within 1 nm would be obtained over 20 measurement points in case of the calibration of CD-SEM using 240-nm pitch standard reference grating, 1,2) as the standard deviation was 2.2 nm by the CD-SEM measurement. Moreover by using grating reference fabricated by EB cell projection lithography and silicon dry etching, more accurate calibration within 0.5 nm in error or convenient calibration with small measurement points less than 10 will be expected.…”

“…In order to calibrate electron-beam (EB) metrology systems, a fine 240-nm pitch reference grating 1,2) fabricated by laser-interferometer lithography and anisotropic chemical etching is widely used. However, a pitch grating finer than 200 nm is required for sub-100 nm device manufacture, because one pitch of the conventional reference goes over the frame of scanning field of the critical-dimension scanning electron microscope (CD-SEM) in higher magnification for sub-100 nm device evaluation.…”

Submicrometre-pitch intercomparison between optical diffraction, scanning electron microscope and atomic force microscope

“…According to the above conditions, three samples of standard microscales (nominal pitch value: 240 nm) for the calibration of SEM magnification made by Hitachi Science Systems were selected as the standard samples for the intercomparison [8,9]. Grating patterns were fabricated over the entire surface of the (110)Si substrate (4 mm × 4 mm × 0.3 mm).…”

Effective Linewidth Measurement of 45-nm-Half-Pitch Ultraviolet Nanoimprint Lithography Patterns by Scanning Electron Microscope Inspection and Extremely Shallow Si Etching

“…Si is used for standard microscale samples of SEM owing to the fact that Si can produce high-contrast signals of EB and enables stable measurement at high acceleration voltages without causing any charge buildup; moreover, there are almost no aginginduced changes in this process. 19) In this study, we first describe in detail the shrinkage problem encountered during SEM inspection of sub-100 nm patterns fabricated by UV nanoimprint. Next, we evaluate the pattern widths by the proposed method using sequential dry etching for residual layer removal and pattern transfer.…”