SBIR Phase I: Batch Wafer-Scale Fabrication of Improved Probe Tips for Scanned Probe Microscopy

This Small Business Innovation Research Phase I project will focus on the development and scale-up of a new process for fabricating probe tips for atomic force microscopy (AFM). In AFM, images of surfaces with atomic-scale resolution are created by rastering a probe across the surface. The probe itself consists of a tip (which interacts with the surface) and a body (which supports the tip and provides an externally-readable signal). The tip radius of curvature determines the size of the smallest surface feature that may be imaged, and the tip composition establishes its hardness and thus its wear resistance. One of the main impediments to wider adoption of AFM has been the poor durability of probe tips. This project will lead to the first batch process to fabricate tips that are both extremely sharp and hard. The new process involves two steps. First, chemical vapor deposition (CVD) is used to coat the tips with a chemically inert and extremely hard material. Second, field directed sputter sharpening (FDSS) sharpens the probe tip to atomic dimensions. The broader impacts/commercial potential of this project are significant. At present, the CVD/FDSS process has been implemented for coating and sharpening only one tip at a time in a laboratory setting. The current project, which will develop batch wafer-scale processing so that dozens or hundreds of tips can be coated and sharpened at once, will form the basis for a process to manufacture and sell AFM probe tips that are ultra-sharp, very hard, and relatively inexpensive. The availability of such probe tips could lead to a significant expansion of the market for AFM probe tips, which is currently approximately $35 million per year and growing rapidly. The results will significantly enhance the capabilities of all probe microscopy methods, including AFM and related techniques such as scanning spreading resistance microscopy (SSRM) and electrochemical imaging (ECAFM). The research will also be of benefit to those who image insulating surfaces, such as polymers and other soft materials where static charge build-up limits efficacy. In addition, the results of this project could be extended to multi-tip probe arrays for lithographic and nanomanufacturing applications, and to the on-board testing of integrated circuits for delay faults, a capability of great interest to the microelectronics industry.