Surface measurements in three dimensional (3D)-Nanometrology become more complex and demanding. 3D geometries of dense structures, narrow trenches and vias with steep sidewalls cannot be measured completely in one orientation, which enlarges the measurement uncertainty. A small measurement uncertainty is desirable because accurate and absolute measurements allow the development of novel products and control processes around the world which leads to prosperity of mankind. As the complexity of small structures reaches the level of macroscopic parts, measurement tasks or processes that seem to be state of the art in the macroscopic world cannot be fulfilled or applied at the nanoscale, simply because the specific sensors required for those measurements are not developed. The workhorse in dimensional nanometrology is the atomic force microscope (AFM) and modifications of it. This measurement tool uses a small bendable probe, which interacts with the surface of a sample. The surface forces deflect the cantilever probe elastically. The deformation of the probe is detected and used to trace the surface topography point by point. Multiple traces are usually rendered to a 3D appearing image of the topography of the sample surface. Without further data processing this image contains image artifacts such as the dilation with the apparent tip apex geometry, which is immanent to the principle of probing with a tip. Consequently, sharp features appear rounded, trenches appear narrower and sidewall angles of structures appear with the cone angle of the tip of the probe. Especially for narrow trenches, critical dimensions (CD) and steep sidewalls the CD-AFM was invented. Despite the use of a special probe with flared tip apex and dual-axis tip control this AFM shows limits and cannot probe in true 3D.

Within this thesis a novel sensor is developed which can be applied to measure 3D topographies at the nanoscale in one measurement. Based on the CD-AFM working principle a new cantilever based probe is modified to be sensitive for three orthogonal spatial directions (3D), enhancing state of the art probing by and additional degree of freedom. The novel cantileverbased probe is denoted as the 3D-Nanoprobe. It is optimized for isotropic stiffness to reduce tip-slipping during probing and its overall stiffness is adapted to the compliant flared tip, to improve sensitivity for slender and small tip geometries. Essential for the 3D-Nanoprobe is, it is selective for 3D by means of the developed and optimized structure. The 3D-Nanoprobe consists of two head sections, optimized for an optical detection system. The head sections are connected by flexure hinge structures, to balance the mechanical properties of the probe. In this work, the 3D Nanoprobe is used in contact mode for true 3D-probing. The resonance frequencies of the 3D Nanoprobe are separable and above 70 kHz for fast probing and allows other operating modes in the future. The 3D-Nanoprobe is applied in a novel 3D-AFM head and verified to be a true 3D sensor for 3D-Nanometrology.

The optical detection system of the 3D-AFM head is a hybrid combination of a differential working interferometer and a dual optical lever. The interferometer mainly detects the first head section’s displacement of the 3D-Nanoprobe in vertical z-direction. The dual optical lever detects the inclination angles of the second head section induced by bending and torsion of the flexure hinges due to tip apex displacements in horizontal x- and y-directions. After calibration the developed true 3D-AFM head shows a selectivity ratio to register 3D tip apex displacements in spatial directions of about 50:1 and a probing repeatability of <1 nm in x-, y-, z-directions.