"Design of an Atomic Force Microscope with Interferometric Position Control."

Schneir, J.; McWaid, T.H.; Alexander, J.; Wilfley, B.P.

(38th International Symposium on Electron Ion and Photon Beams (EIPB'94), New Orleans, LA, USA, 31 May-3 June 1994).

Journal of Vacuum Science & Technology B (Microelectronics and Nanometer Structures), Nov.-Dec. 1994, vol.12, (no.6):3561-6.

Abstract: Advances in the manufacture of integrated circuits, x-ray optics, magnetic read-write heads, optical data storage media, and razor blades require advances in ultraprecision metrology. Each of these industries is currently investigating the use of atomic force microscopy (AFM) to improve the precision and accuracy of their manufacturing process control. To facilitate the use of AFMs for manufacturing we have developed an AFM capable of making accurate dimensional measurements. We call this system the calibrated AFM (C-AFM). The C-AFM has been constructed as much as possible out of commercially available components. We use a flexure stage driven by piezoelectric transducers for scanning, a heterodyne interferometer to measure the X and Y displacements of the sample, a capacitance sensor to measure the Z displacement of the sample, and a commercially available AFM control system. The control system has two feedback loops, which read from the X and Y interferometers, respectively, and adjust the piezoelectric voltages to keep the X-Y scan position accurate. The critical electromechanical and metrology issues involved in the construction and operation of such a system will be discussed in detail.

"Nanometer-scale Lithography using the Atomic Force Microscope. "

Majumdar, A.; Oden, P.I.; Carrejo, J.P.; Nagahara, L.A.; Graham, J.J.; Alexander, J.

Applied Physics Letters, 9 Nov. 1992, vol.61, (no.19):2293-5.

Abstract: The authors demonstrate a new use of the atomic force microscope (AFM) for nanometer-scale lithography on ultrathin films of poly(methylmethacrylate) (PMMA). The PMMA films were chemically modified as both positive and negative resists due to energy transfer from a highly localized electron source provided by metallized AFM tips. The authors were able to fabricate a line pattern with 68 nm line periodicity with about 35 nm line widths.

"A Study of Surface Reactions and Adhesion Using IETS "

P. N. Henriksen, R. D. Ramsier, J. D. Alexander

Surface and Interface Analysis Vol. 11, 283-286 (1988)

Abstract: Can not locate abstract at this time.

"Resistive and Transverse Magnetoresistance in Ultrathin Films of Pure Bismuth."

Chu, H.T.; Henriksen, P.N.; Alexander, J.

Physical Review B (Condensed Matter), 15 March 1988, vol.37, (no.8):3900-5.

Abstract: Electrical resistivity and transverse magnetoresistance were measured at liquid-helium temperatures in thin films of pure bismuth ranging from 101 to 4504 A in magnetic fields up to a maximum of 80 kG. The films could be divided into two groups, above and below a thickness of about 250 A. The resistivity (in zero magnetic field) and the magnetoresistance were found to be drastically different, both in magnitude and variation as a function of field strength, for the two groups. Interpretation is given in terms of a transition, due to the quantum size effect, of the charge carriers from states of three-dimensional motion in the thicker films to states of two-dimensional motion in the thinner films.

"Inelastic Electron Tunneling Spectroscopy of Silane Coupling Agents Adsorbed on Alumina. "

Alexander, J.D.; Gent, A.N.; Henriksen, P.N.

Journal of Chemical Physics, 1 Dec. 1985, vol.83, (no.11):5981-7.

Abstract: Inelastic electron tunneling spectroscopy (IETS) has been used to obtain vibrational spectra of alkoxysilanes adsorbed on aluminum oxide. The spectra reveal that: (1) monoalkoxysilanes are not adsorbed whereas trialkoxysilanes are readily adsorbed, (2) the reaction mechanism of triethoxysilanes and trimethoxysilanes is the same, and (3) the reaction mechanism under anhydrous conditions utilizes surface OH or OD groups present on alumina. These results support the hypothesis that the alkoxy groups exchange with OH groups on the surface to form siloxane bonds, and that these bonds are stabilized with trialkoxysilanes. For monoalkoxysilanes, either the bonds do not form so readily, or they are not stabilized by further condensation of the adsorbed species. Instead, the monoalkoxysilanes appear to catalyze further oxidation of the alumina surface.