Abstract: A structure formed on a wafer can be examined by directing an incident pulse at the structure, the incident pulse being a sub-picosecond optical pulse. A diffraction pulse resulting from the incident pulse diffracting from the structure is measured. A characteristic of the profile of the structure is then determined based on the measured diffraction pulse.

Abstract: Edge roughness and deterministic profile of a structure formed on a semiconductor wafer are measured using optical metrology by directing an incident beam on the structure using a source and receiving the diffracted beam from the structure using a detector. The received diffracted beam is processed using a processor to determine a deterministic profile of the structure and to measure an edge roughness of the structure.

Abstract: The profile of a single feature formed on a wafer can be determined by obtaining an optical signature of the single feature using a beam of light focused on the single feature. The obtained optical signature can then be compared to a set of simulated optical signatures, where each simulated optical signature corresponds to a hypothetical profile of the single feature and is modeled based on the hypothetical profile.

Abstract: A simulated diffraction signal to be used in measuring shape roughness of a structure formed on a wafer using optical metrology is generated by defining an initial model of the structure. A statistical function of shape roughness is defined. A statistical perturbation is derived based on the statistical function and superimposed on the initial model of the structure to define a modified model of the structure. A simulated diffraction signal is generated based on the modified model of the structure.

Abstract: The top-view profiles of repeating structures in a wafer are characterized and parameters to represent variations in the top-view profile of the repeating structures are selected. An optical metrology model is developed that includes the selected top-view profile parameters of the repeating structures. The optimized optical metrology model is used to generate simulated diffraction signals that are compared to measured diffraction signals.

Abstract: Overlay measurements for a semiconductor wafer are obtained by forming a periodic grating on the wafer having a first set of ridges and a second set of ridges. The first and second sets of ridges are formed on the wafer using a first mask and a second mask, respectively. After forming the first and second sets of gratings, zero-order cross polarization measurements of a portion of the periodic grating are obtained. Any overlay error between the first and second masks used to form the first and second sets of gratings is determined based on the obtained zero-order cross polarization measurements.

Abstract: A structure formed on a semiconductor wafer is examined by directing an incident beam at the structure at an incidence angle and a azimuth angle. The incident beam is scanned over a range of azimuth angles to obtain an azimuthal scan. The cross polarization components of diffracted beams are measured during the azimuthal scan.

Abstract: Overlay measurements for a semiconductor wafer are obtained by forming a periodic grating on the wafer having a first set of ridges and a second set of ridges. The first and second sets of ridges are formed on the wafer using a first mask and a second mask, respectively. After forming the first and second sets of gratings, zero-order cross polarization measurements of a portion of the periodic grating are obtained. Any overlay error between the first and second masks used to form the first and second sets of gratings is determined based on the obtained zero-order cross polarization measurements.

Abstract: A resolution enhanced optical metrology system to examine a structure formed on a semiconductor wafer includes a source configured to direct an incident beam at the structure through a coupling element. The coupling element is disposed between the source and the structure with a gap having a gap height defined between the coupling element and the structure.

Abstract: Edge roughness and deterministic profile of a structure formed on a semiconductor wafer are measured using optical metrology by directing an incident beam on the structure using a source and receiving the diffracted beam from the structure using a detector. The received diffracted beam is processed using a processor to determine a deterministic profile of the structure and to measure an edge roughness of the structure.

Abstract: The profile of a single feature formed on a wafer can be determined by obtaining an optical signature of the single feature using a beam of light focused on the single feature. The obtained optical signature can then be compared to a set of simulated optical signatures, where each simulated optical signature corresponds to a hypothetical profile of the single feature and is modeled based on the hypothetical profile.

Abstract: Overlay measurements for a semiconductor wafer are obtained by forming a periodic grating on the wafer having a first set of ridges and a second set of ridges. The first and second sets of ridges are formed on the wafer using a first mask and a second mask, respectively. After forming the first and second sets of gratings, zero-order cross polarization measurements of a portion of the periodic grating are obtained. Any overlay error between the first and second masks used to form the first and second sets of gratings is determined based on the obtained zero-order cross polarization measurements.

Abstract: Eigensolutions for use in determining the profile of a structure formed on a semiconductor wafer can be approximated by obtaining a known set of eigenvectors associated with a first section of a hypothetical profile of the structure, where the known set of eigenvectors is used to generate a simulated diffraction signal for the hypothetical profile. A known characteristic matrix associated with a second section of a hypothetical profile is obtained, and an approximated set of eigenvalues for the second section is determined based on the known set of eigenvectors associated with the first section and the known characteristic matrix associated with the second section.

Abstract: The profile of a single feature formed on a wafer can be determined by obtaining an optical signature of the single feature using a beam of light focused on the single feature. The obtained optical signature can then be compared to a set of simulated optical signatures, where each simulated optical signature corresponds to a hypothetical profile of the single feature and is modeled based on the hypothetical profile.

Abstract: Overlay measurements for a semiconductor wafer are obtained by forming a periodic grating on the wafer having a first set of gratings and a second set of gratings. The first and second sets of gratings are formed on the wafer using a first mask and a second mask, respectively. The first and second sets of gratings are intended to be formed on the wafer with an intended asymmetrical alignment. A diffraction signal of the first and second sets of gratings is measured after the first and second sets of gratings are formed on the wafer. The misalignment between the first and second sets of gratings formed on the wafer is determined based on the measured diffraction signal.

Abstract: One or more simulated diffraction signals for use in determining the profile of a structure formed on a semiconductor wafer can be generated, where the profile varies in more than one dimension. Intermediate calculations are generated for variations in a hypothetical profile of the structure in a first dimension and a second dimension, where each intermediate calculation corresponds to a portion of the hypothetical profile of the structure. The generated intermediate calculations are then stored and used in generating one or more simulated diffraction signals for one or more hypothetical profiles of the structure.

Abstract: The profile of a single feature formed on a wafer can be determined by obtaining an optical signature of the single feature using a beam of light focused on the single feature. The obtained optical signature can then be compared to a set of simulated optical signatures, where each simulated optical signature corresponds to a hypothetical profile of the single feature and is modeled based on the hypothetical profile.

Abstract: Overlay measurements for a semiconductor wafer are obtained by forming a periodic grating on the wafer having a first set of gratings and a second set of gratings. The first and second sets of gratings are formed on the wafer using a first mask and a second mask, respectively. The first and second sets of gratings are intended to be formed on the wafer with an intended asymmetrical alignment. A diffraction signal of the first and second sets of gratings is measured after the first and second sets of gratings are formed on the wafer. The misalignment between the first and second sets of gratings formed on the wafer is determined based on the measured diffraction signal.

Abstract: Overlay measurements for a semiconductor wafer are obtained by forming a periodic grating on the wafer having a first set of ridges and a second set of ridges. The first and second sets of ridges are formed on the wafer using a first mask and a second mask, respectively. After forming the first and second sets of gratings, zero-order cross polarization measurements of a portion of the periodic grating are obtained. Any overlay error between the first and second masks used to form the first and second sets of gratings is determined based on the obtained zero-order cross polarization measurements.