Three-dimensional imaging with enhanced resolution

An imaging system comprising:

• an imaging metrology tool, wherein aberration correction of the imaging metrology tool is adjustable within three or more degrees of freedom, wherein the imaging metrology tool comprises:
• a translation stage for securing a sample;
• an illumination source;
• one or more illumination optics to direct illumination from the illumination source to the sample;
• a detector;
• one or more collection optics to image the sample onto the detector;
• and
• one or more aberration-controlling components providing aberration correction for imaging the sample onto the detector according to the three or more degrees of freedom, wherein the one or more aberration-controlling components are integrated with at least one of the one or more illumination optics, the one or more collection optics, the detector, or the translation stage, wherein the one or more aberration-controlling components are adjustable in both position and rotation;
• and
• a controller including one or more processors configured to execute program instructions causing the one or more processors to:
• determine configurations of the one or more aberration-controlling components associated with the three or more degrees of freedom providing imaging of the sample onto the detector with a quality metric above a selected threshold for a plurality of imaging depths;
• and
• direct the imaging metrology tool to image at least a portion of the sample at two or more imaging depths in the plurality of imaging depths using the determined configurations of the imaging metrology tool, wherein the imaging metrology tool is configured for sub-surface imaging at a range of sample depths, wherein the one or more aberration-controlling components are configured to maintain imaging quality across all depths within the range of sample depths by adjusting at least one of the three or more degrees of freedom for aberration control.

An imaging method comprising:

• determining configurations of one or more aberration-controlling components associated with three or more degrees of freedom providing imaging of a sample with a quality metric above a selected threshold for a plurality of imaging depths with an imaging metrology tool, wherein the imaging metrology tool comprises:
• an illumination source to generate an illumination beam;
• one or more illumination optics to direct the illumination beam to the sample;
• a translation stage, wherein the three or more degrees of freedom include a sample defocus position corresponding to a position of the translation stage along an optical axis of the one or more illumination optics;
• an imaging detector;
• and
• one or more collection optics to collect light from the sample as collected light and direct at least a portion of the collected light to the imaging detector, wherein the collection optics include one or more adjustable optical elements, wherein the three or more degrees of freedom include configurations of the one or more adjustable optical elements, wherein the one or more aberration-controlling components are adjustable in both position and rotation;
• and
• imaging at least a portion of the sample at two or more imaging depths using the determined configurations of the imaging metrology tool, wherein the imaging comprises sub-surface imaging at a range of sample depths, wherein the one or more aberration-controlling components are configured to maintain imaging quality across all depths within the range of sample depths by adjusting at least one of the three or more degrees of freedom for aberration control.