Su Chanmin, Huang Lin, Kjoller Kevin, Babcock Ken
Digital Instruments/Veeco Metrology Group, 112 Robin Hill Road, Santa Barbara, CA 93117, USA.
Ultramicroscopy. 2003 Oct-Nov;97(1-4):135-44. doi: 10.1016/s0304-3991(03)00038-x.
Tip integrity is crucial to atomic force microscope image quality. Tip wear not only compromises image resolution but also introduces artifacts. However, the factors that govern wearing have not been systematically studied. The results presented here of tip wearing on a rough titanium surface were determined by monitoring changes in tip shape and the evolution of histograms of complex surface curvatures under different control parameters. In contrast with the common assumption that operating at a low set point (the ratio of tapping amplitude to free oscillation amplitude) wears the tip quickly, we observed that a low set point actually minimizes tip wear on a hard surface regardless of the free amplitude. The results can be interpreted qualitatively with theoretical calculations based on momentum exchange at tapping impact. Operating at a low set point allows more robust scanning than with a high set point (tapping near free amplitude), providing a method to slow down tip wear. Another advantage of a low set point is that amplitude error grows faster than with a high set point by nearly an order of magnitude, permitting an increase in scanning speed.
针尖完整性对于原子力显微镜图像质量至关重要。针尖磨损不仅会降低图像分辨率，还会引入伪像。然而，影响磨损的因素尚未得到系统研究。此处呈现的在粗糙钛表面上针尖磨损的结果是通过监测针尖形状的变化以及在不同控制参数下复杂表面曲率直方图的演变来确定的。与通常认为在低设定点（轻敲幅度与自由振荡幅度之比）下操作会使针尖快速磨损的假设相反，我们观察到，无论自由幅度如何，低设定点实际上能使硬表面上的针尖磨损最小化。这些结果可以通过基于轻敲撞击时动量交换的理论计算进行定性解释。与高设定点（在接近自由幅度处轻敲）相比，在低设定点下操作能实现更稳健的扫描，提供了一种减缓针尖磨损的方法。低设定点的另一个优点是，幅度误差的增长速度比高设定点快近一个数量级，从而可以提高扫描速度。
