| 摘要 |
<p>An electron beam (10) transversely scans a planar surface (18) having a longitudinal structure (20) projecting therefrom. Two Everhart-Thomley detectors (30, 32) are positioned on transversely opposite sides, respectively, of the structure (20). During a first scan, only one detector (30) is turned ON to produce a first electric signal having a pronounced amplitude dip corresponding to the structure's bottom edge (28) which is facing away from the ON detector (30). During the next scan, only the other detector (32) is turned ON to produce a second electric signal having a pronounced amplitude dip corresponding to the structure's other bottom edge (24) which is now facing away from the ON detector (32). The two signals are combined to produce a composite signal whose waveform comprises two enhanced and segmented dips corresponding to the locations of the structure's two bottom edges (24, 28).</p> |
