Kinoshita Yukinori, Naitoh Yoshitaka, Li Yan Jun, Sugawara Yasuhiro
Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
Rev Sci Instrum. 2011 Nov;82(11):113707. doi: 10.1063/1.3663069.
Tungsten (W) is significantly suitable as a tip material for atomic force microscopy (AFM) because its high mechanical stiffness enables the stable detection of tip-sample interaction forces. We have developed W sputter-coating equipment to compensate the drawbacks of conventional Si cantilever tips used in AFM measurements. By employing an ion gun commonly used for sputter cleaning of a cantilever tip, the equipment is capable of depositing conductive W films in the preparation chamber of a general ultrahigh vacuum (UHV)-AFM system without the need for an additional chamber or transfer system. This enables W coating of a cantilever tip immediately after sputter cleaning of the tip apex and just before the use in AFM observations. The W film consists of grain structures, which prevent tip dulling and provide sharpness (<3 nm in radius of curvature at the apex) comparable to that of the original Si tip apex. We demonstrate that in non-contact (NC)-AFM measurement, a W-coated Si tip can clearly resolve the atomic structures of a Ge(001) surface without any artifacts, indicating that, as a force sensor, the fabricated W-coated Si tip is superior to a bare Si tip.
钨（W）非常适合作为原子力显微镜（AFM）的针尖材料，因为其高机械刚度能够稳定检测针尖与样品之间的相互作用力。我们开发了钨溅射镀膜设备，以弥补原子力显微镜测量中使用的传统硅悬臂梁针尖的缺点。通过使用常用于悬臂梁针尖溅射清洗的离子枪，该设备能够在普通超高真空（UHV）-AFM系统的制备室中沉积导电钨膜，而无需额外的腔室或传输系统。这使得在对针尖顶端进行溅射清洗后且即将用于AFM观察之前，能够立即对悬臂梁针尖进行钨镀膜。钨膜由晶粒结构组成，可防止针尖变钝，并提供与原始硅针尖顶端相当的尖锐度（顶端曲率半径<3 nm）。我们证明，在非接触（NC）-AFM测量中，涂有钨的硅针尖能够清晰地分辨Ge(001)表面的原子结构，且无任何伪像，这表明，作为力传感器，制备的涂有钨的硅针尖优于裸硅针尖。
