Accession Number : ADA311032

Title :   Scanning Probe Lithography. 4. Effect of Scanning Tunneling Microscope Tip Parameters on Lithographic Patterns in Self-Assembling Monolayers.

Descriptive Note : Technical rept. 1 Jun 95-31 May 96,

Corporate Author : TEXAS A AND M UNIV COLLEGE STATION DEPT OF CHEMISTRY

Personal Author(s) : Schoer, Jonathan K. ; Crooks, Richard M.

PDF Url : ADA311032

Report Date : 24 JUN 1996

Pagination or Media Count : 55

Abstract : Here we examine the effect of an STM tip on a Au-confined n-octadecyl mercaptan, HS(CH2)17CH3, SAM in air. We have determined that STM-induced lithography is controlled by a complex combination of parameters defined by both the instrument and the chemical and physical properties of materials in the vicinity of the tip. We have identified conditions that permit accurate control of the tip position during patterning, so we are able to prevent large tip excursions that lead to mixed patterning mechanisms. We propose a multi-step model in which the n-octadecyl mercaptan monolayer is: (1) disrupted by the tip, (2) electrochemically desorbed, and (3) removed by the scanning action of the tip. Once the passivating SAM is removed, additional patterning etches the exposed Au substrate. In addition to the primary pattern, we observe an irregularly shaped region of the surface that is disordered for 1 - >500 nm beyond the primary pattern. This disordered region represents an early stage of the patterning and indicates that the resolution of this technique is limited by the electrochemical nature of the patterning process. In some cases it is possible to form secondary patterns from protrusions on the tip. Patterns on n-octadecyl mercaptan coated-Au(111) defined in this manner are dimensionally stable for several days. The results provide further insight into this alternative approach to conventional lithography.

Descriptors :   *ETCHING, *LITHOGRAPHY, CONTROL, SCANNING ELECTRON MICROSCOPES, TUNNELING(ELECTRONICS), ACCURACY, ORDER DISORDER TRANSFORMATIONS, ALKANES, POLYMERIC FILMS, PATTERNS, THIOLS.

Subject Categories : Mfg & Industrial Eng & Control of Product Sys

Distribution Statement : APPROVED FOR PUBLIC RELEASE