Generating a library of simulated-diffraction signals and hypothetical profiles of periodic gratings

A method of generating a library of simulated-diffraction signals and hypothetical profiles of a periodic grating, said method comprising:

• generating diffraction calculations for a plurality of blocks of hypothetical layers,
• wherein each block of hypothetical layers includes two or more hypothetical layers;
• storing the diffraction calculations generated for the blocks of hypothetical layers;
• and
• generating simulated-diffraction signals for a plurality of hypothetical profiles of the periodic grating, wherein for each hypothetical profile:
• at least one block of hypothetical layers is selected that characterizes the hypothetical profile,
• the diffraction calculation associated with the selected block of hypothetical layers is retrieved,
• a simulated-diffraction signal for the hypothetical profile is generated based on the retrieved diffraction calculation, and
• the hypothetical profile and the generated simulated-diffraction signal are stored.

A method of generating a library of simulated-diffraction signals for a periodic grating, said method comprising:

• generating diffraction calculations for a plurality of hypothetical layers;
• forming a plurality of blocks of hypothetical layers,
• wherein two or more hypothetical layers are grouped together to form each block of hypothetical layers, and
• wherein for each block of hypothetical layers:
• the diffraction calculations of the hypothetical layers within the block of hypothetical layers is aggregated to generate a diffraction calculation for the block of hypothetical layers;
• storing the diffraction calculations generated for the blocks of hypothetical layers;
• generating a plurality of hypothetical profiles of the periodic grating;
• generating a simulated-diffraction signal for each hypothetical profile based on the stored diffraction calculations for the blocks of hypothetical layers;
• and
• storing the generated simulated-diffraction signal.

A system for generating a library of simulated-diffraction signals for a periodic grating, said system comprising:

• a processor configured to generate diffraction calculations for a plurality of blocks of hypothetical layers,
• wherein each block of hypothetical layers includes two or more hypothetical layers;
• a memory configured to store the diffraction calculations generated for the blocks of hypothetical layers;
• and
• wherein the processor is further configured to:
• generate simulated-diffraction signals for a set of hypothetical profiles of the periodic grating based on the diffraction calculations stored in the memory.

A computer-readable storage medium containing computer executable instructions for causing a computer to generate a library of simulated-diffraction signals to be used in obtaining profiles of a periodic grating, comprising instructions for:

• generating diffraction calculations for a plurality of hypothetical layers;
• forming a plurality of blocks of hypothetical layers,
• wherein two or more hypothetical layers are grouped together to form each block of hypothetical layers, and
• wherein the diffraction calculations of the two or more hypothetical layers are aggregated together to generate a diffraction calculation for each block of hypothetical layers;
• storing the diffraction calculations generated for the blocks of hypothetical layers;
• generating a plurality of hypothetical profiles of the periodic grating;
• and
• generating simulated-diffraction signals for each of the hypothetical profiles, further comprising:
• selecting at least one block of hypothetical layers that characterizes the hypothetical profile,
• retrieving the diffraction calculation associated with the selected block of hypothetical layers,
• generating a simulated-diffraction signal for the hypothetical profile utilizing the retrieved diffraction calculation, and
• storing the hypothetical profile and the generated simulated-diffraction signal.