Method and apparatus for aligning a probe for scanning probe microscopy to the tip of a pointed sample

An SPM apparatus comprising:

• an SPM probe mounted on a cantilever, wherein the cantilever has a fixed end and a free end, wherein the SPM probe is mounted on the free end of the cantilever, and wherein the SPM probe has a base and a tip;
• a sample holder;
• a drive mechanism for driving a movement of the SPM probe relative to the sample holder;
• and
• detection, control, and representation tools for acquiring and representing an image of a surface scanned in two dimensions by the SPM probe, wherein the SPM apparatus is configured to automatically perform the following steps for aligning the SPM probe to a tip of a pointed sample mounted in the sample holder and configured so that an electric field or a magnetic field appears around the tip of the pointed sample with a field strength being highest at the tip of the pointed sample and deteriorating radially away from the tip of the pointed sample:
• performing an SPM acquisition scan of the SPM probe in a 2-dimensional area so that the tip of the pointed sample is positioned in the projection of the 2-dimensional area along a longitudinal direction of the pointed sample, wherein the SPM acquisition scan is performed in a contactless SPM acquisition mode suitable for detecting the field;
• evaluating the acquired image;
• if the field is not detected, repeating the scanning and evaluation steps at consecutive smaller distances from the tip of the pointed sample;
• detecting the field by observing an area in the acquired image, wherein the area in the acquired image exhibits a gradient of a measured SPM probe parameter, thereby allowing an estimation of a position of the tip of the pointed sample;
• further repeating the scanning and evaluating steps at consecutive smaller distances, each time obtaining a more accurate determination of a position of an apex area of the tip of the pointed sample, until the position of the apex area of the tip of the pointed sample is determined with an accuracy that allows placing the SPM probe in a position where a probe tip of the SPM probe is aligned to the apex area of the tip of the pointed sample;
• and
• placing the SPM probe in the position where the probe tip of the SPM probe is aligned to the apex area of the tip of the pointed sample, either:
• at the end of the repeated scanning and evaluation steps;
• or
• by repositioning the SPM probe one or more times after one or more respective scanning steps and progressively reducing a scanning area around the position of the tip of the pointed sample.

A Scanning Probe Microscopy (SPM) probe aligned to an apex area of a free-standing tip of a pointed sample, wherein the SPM probe is aligned using a method comprising:

• providing an SPM apparatus comprising:
• the SPM probe mounted on a cantilever, wherein the cantilever comprises a fixed end and a free end, wherein the SPM probe is mounted on the free end of the cantilever, and wherein the SPM probe has a base and a tip;
• a sample holder;
• a drive mechanism for driving a movement of the SPM probe relative to the sample holder;
• and
• detection, control, and representation tools for acquiring and representing an image of a surface scanned in two dimensions by the SPM probe, wherein the image is based on values of a SPM probe parameter measured during the scan;
• mounting the sample on the sample holder with the free-standing tip of the pointed sample pointed towards the cantilever and the SPM probe, wherein the pointed sample is configured so that an electric field or a magnetic field appears around the free-standing tip of the pointed sample, and wherein a field strength is highest at the free-standing tip and deteriorates radially away from the free-standing tip;
• positioning a probe tip of the SPM in a first position at a distance from the free-standing tip of the pointed sample;
• determining a 2-dimensional area so that the free-standing tip of the pointed sample is positioned in the projection of the 2-dimensional area along a longitudinal direction of the pointed sample;
• performing an SPM acquisition scan of the SPM probe in the 2-dimensional area, wherein the SPM acquisition scan is performed in a contactless SPM acquisition mode suitable for detecting the field;
• evaluating the acquired image;
• if the field is not detected, repeating the scanning and evaluation steps at consecutive smaller distances from the free-standing tip of the pointed sample;
• detecting the field by observing an area in the acquired image, wherein the area in the acquired image exhibits a gradient of the measured SPM probe parameter, thereby allowing an estimation of a position of the free-standing tip of the pointed sample;
• further repeating the scanning and evaluating steps at consecutive smaller distances, each time obtaining a more accurate determination of a position of the apex area of the free-standing tip of the pointed sample, until the position of the apex area is determined with an accuracy that allows placing the SPM probe in a position where the probe tip of the SPM is aligned to the apex area of the free-standing tip of the pointed sample;
• and
• placing the SPM probe in the position where the probe tip of the SPM is aligned to the apex area of the free-standing tip of the pointed sample, either:
• at the end of the repeated scanning and evaluation steps;
• or
• by repositioning the SPM probe one or more times after one or more respective scanning steps and progressively reducing a scanning area around a position of the free-standing tip of the pointed sample.