title: High speed nano-metrology.
abstract: For manufacturing at the nanometre scale a method for rapid and accurate measurement of the resultant functional devices is required. Although atomic force microscopy (AFM) has the requisite spatial resolution, it is severely limited in scan speed, the resolution and repeatability of vertical and lateral measurements being degraded when speed is increased. Here we present a new approach to AFM that makes a direct and feedback-independent measurement of surface height using a laser interferometer focused onto the back of the AFM tip. Combining this direct height measurement with a passive, feedback-free method for maintaining tip-sample contact removes the constraint on scan speed that comes from the bandwidth of the z-feedback loop. Conventional laser reflection detection is used for feedback control, which now plays the role of minimising tip-sample forces, rather than producing the sample topography. Using the system in conjunction with a rapid scanner, true height images are obtained with areas up to (36 × 36) μm(2) at 1 image/second, suitable for in-line applications.
authors.affiliation: Infinitesima Ltd, Oxford Centre for Innovation, Mill St., Oxford OX2 0JX, United Kingdom.
authors.forename: Andrew D L
authors.initials: AD
authors.lastname: Humphris
authors.forename: Bin
authors.initials: B
authors.lastname: Zhao
authors.forename: David
authors.initials: D
authors.lastname: Catto
authors.forename: Jeremy P
authors.initials: JP
authors.lastname: Howard-Knight
authors.forename: Priyanka
authors.initials: P
authors.lastname: Kohli
authors.forename: Jamie K
authors.initials: JK
authors.lastname: Hobbs
mesh_terms: D002138:Calibration; D020342:Finite Element Analysis; D018625:Microscopy, Atomic Force / Q000295:instrumentation / Q000379:methods*; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D012666:Semiconductors; D012825:Silicon; D013997:Time Factors
chemical_list: D012825:Silicon