Linewidth measurement on IC masks and wafers by grating test patterns

Abstract

Test patterns in the form of diffraction gratings are used for testing and monitoring linewidths on integrated circuit structures. The first and second diffraction orders produed by a laser beam are evaluated to give the width of the grating lines. Measurements on chrome masks show that this technique is accurate to 5% down to linewidths of 0.5 microm. The design of a test set for factory type mask testing is presented. Also, experiments are reported on the testing of patterns on Si wafers directly after. photoresist development and after various etching steps, and an-automatic setup for rapid testing of wafers is described.

Normal-incidence spectroscopic ellipsometry for critical dimension monitoring

“…Optical reflection techniques employing quantitative analysis of diffraction from gratings have been explored as possible supplementary measurements to CD SEMs. [2][3][4] The scattered light from gratings produces strong structures ͑Wood's anomalies 5 ͒ in reflectance spectra-both as a function of angle of incidence ͑AOI͒ ͑Refs. 6 and 7͒ and wavelength [8][9][10] which are very sensitive to the topography of the grating.…”

Study on the feasibility of measuring relief grating parameters through the transmission spectrum

“…Theoretical analysis and numerical simulation results demonstrate the feasibility and validity of the proposed method. This method not only provides a new and promising way to measure microstructure parameters in the field of grating manufacture but also will be used in other microstructure application such as critical dimension measurement in integrated circuit production of semiconductor industry [12] .…”

Diffractive optics calibrator: measurement of etching variations for binary computer-generated holograms

“…The common range of the grating periods is from 5 to 30 μm, which is well within the limits of scalar diffraction theory [6]. Therefore, one can write an analytical expression for the diffraction efficiency as a function of the duty cycle and the etching depth [7,8]. This relationship is applied to a new device: the diffractive optics calibrator (DOC).…”