Method for Determining the Angle in Two Dimension Nanoscale: Pitch Grating

Pitch calibration of standard nanoscale for uncertainty reduction of certified reference materials for SEM image sharpness evaluation and magnification calibration

“…Standard nanoscales are produced by various techniques such as laser interferometer lithography [14], electron beam (EB) cell projection lithography [17,18], and fabrication from multilayer structures [19], depending on their pitch size. Standard nanoscales are usually traceably calibrated to the International System of Units (SI) using diffractometers [22][23][24][25][26][27][28][29][30][31] and/or atomic force microscopes (metrological AFMs) [32][33][34][35][36][37][38][39][40] equipped with laser interferometers. The measurand is an average pitch.…”

“…This commercial standard nanoscale has the advantage of being easy to use in the routine management of SEM, since it also contains the measurement results of single pitches. On the other hand, it is difficult to perform pitch calibration with a smaller uncertainty using an optical diffractometer [22][23][24][25][26][27][28][29][30][31] because the periodic structure is not formed over the entire surface of the sample. To reduce the uncertainty of the certified value of the CRM for image sharpness evaluation and magnification calibration, it is necessary to calibrate the pitch of the standard nanoscale with a metrological AFM as shown in figure 1(b).…”

Natural square ruler at nanoscale

“…T wo-dimensional (2D) nanoscale gratings can be used not only as a transfer standard to calibrate the xy-plane of almost all types of microscopes, [1][2][3][4] but also as a key component in planar encoders to measure 2D displacements. [5][6][7] The fundamental pitch distance along two directions, pitch uniformity, and orthogonality accuracy are the most crucial qualities of the 2D nanogratings for calibration.…”