Critical dimension measurement using new scanning mode and aligned carbon nanotube scanning probe microscope tip

We have developed a new scanning mode and an aligned carbon nanotube tip for atomic force microscopy (AFM) for measuring the critical dimension of deep structures. The aligned carbon nanotube (A-CNT) was assembled in the scanning electron microscope (SEM) chamber. The diameter of the tip is uniformly around 20 nm and the tip attachment angle is within +/- 1.5 degrees to the sample normal. The aspect ratio (length/diameter) of the tip is greater than 30. The new scanning mode is composed of two functions, namely transporting the tip along the steep trench structure and detecting the sample surface. This mode can faithfully trace the steep side wall using a flexible CNT tip without damaging the tip. The critical dimension (CD) measurements of the shallow trench isolation (STI) were performed using the newly developed scanning mode and the A-CNT tip.