Methods And Systems For Scatterometry Based Metrology Of Structures Fabricated On Transparent Substrates

A method comprising:

• generating an amount of illumination light including wavelengths in a range from 150 to 2,500 nanometers;
• directing the amount of illumination light to a measurement spot including one or more structures disposed on an optically transparent substrate with Numerical Aperture (NA) of at least 0.15 and an image demagnification from an illumination field stop to the measurement spot of at least 10, wherein the amount of illumination light is directed to the one or more structures at one or more angles of incidence, one or more azimuth angles, or a combination thereof;
• collecting an amount of collected light from the measurement spot, wherein the collecting involves a collection mask disposed at or near an image plane of a collection optics subsystem, the collection mask including an aperture having a dimension of less than one millimeter in a direction aligned with a direction of changing angle of incidence;
• detecting the amount of collected light;
• and
• generating an estimated value of a first parameter of interest characterizing the one or more structures under measurement based on the detected amount of collected light.

A spectroscopic metrology system comprising:

• an illumination source configured to generate an amount of illumination light including wavelengths in a range from 150 to 2,500 nanometers;
• an illumination optics subsystem configured to direct the amount of illumination light from the illumination source to one or more structures disposed on an optically transparent substrate at a measurement spot at one or more angles of incidence, one or more azimuth angles, or a combination thereof, the illumination optics subsystem having a Numerical Aperture (NA) of at least 0.15 and an image demagnification from an illumination field stop to the measurement spot of at least 10;
• a collection optics subsystem configured to collect an amount of collected light from the measurement spot on the surface of the specimen, the collection optics subsystem including a collection mask disposed at or near an image plane of the collection optics subsystem, the collection mask including an aperture having a dimension of less than one millimeter in a direction aligned with a direction of changing angle of incidence;
• at least one detector having a planar, two-dimensional surface sensitive to incident light, the at least one detector configured to detect the amount of collected light and generate output signals indicative of the detected light;
• and
• a non-transitory, computer-readable medium storing instructions that, when executed by one or more processors, causes the one or more processors to:
• generate an estimated value of a first parameter of interest characterizing the one or more structures under measurement based on an analysis of the output signals.