Analysis of isolated and aperiodic structures with simultaneous multiple angle of incidence measurements
AssigneeTherma-Wave, Inc.
InventorsAllan Rosencwaig, Jon Opsal
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Abstract
A method is disclosed for evaluating isolated and aperiodic structure on a semiconductor sample. A probe beam from a coherent laser source is focused onto the structure in a manner to create a spread of angles incidence. The reflected light is monitored with an array detector. The intensity or polarization state of the reflected beam as a function of radial position within the beam is measured. Each measurement includes both specularly reflected light as well as light that has been scattered from the aperiodic structure into that detection position. The resulting output is evaluated using an aperiodic analysis to determine the geometry of the structure.
Claims15
A method for evaluating the geometry of an aperiodic structure formed on a sample, said method comprising the steps of:
- generating a probe beam of radiation from a coherent light source;
- focusing the probe beam substantially normal onto the aperiodic structure to create a spread of angles of incidence that extends from the normal to at least sixty degrees;
- monitoring the light from the probe beam diffracted from the structure with an array of photodetecting elements and simultaneously generating a plurality of independent output signals corresponding to a range of angles of incidence from the normal of sixty degrees;
- and
- evaluating the geometry of the structure based on the output signals using an analysis which treats the structure as being aperiodic.
A method for evaluating the geometry of a structure formed on a sample, said method comprising the steps of:
- generating a probe beam of radiation from a coherent light source;
- focusing the probe beam substantially normal onto the structure to create a spread of angles of incidence that extends from the normal to at least sixty degrees where the illuminated field is aperiodic;
- monitoring the light from the probe beam diffracted from the structure with an array of photodetecting elements and simultaneously generating a plurality of independent output signals corresponding to a range of angles of incidence from the normal of sixty degrees;
- and
- evaluating the geometry of the structure based on the output signals using an analysis which treats the structure as being aperiodic.
A method for evaluating the geometry of a structure formed on a sample, said structure being defined by ten or fewer longitudinally extending lines, with the width of the structure extending perpendicular to the extending lines, said method comprising the steps of:
- generating a probe beam of radiation from a coherent light source;
- focusing the probe beam substantially normal onto the sample to create a spread of angles of incidence that extends from the normal to at least sixty degrees, wherein the diameter of the focused spot is at least twice the size of the width of the structure;
- monitoring the light from the probe beam diffracted from the structure with an array of photodetecting elements and simultaneously generating a plurality of independent output signals corresponding to a range of angles of incidence from the normal of sixty degrees;
- and
- evaluating the geometry of the structure based on the output signals.
A method for evaluating the geometry of an aperiodic structure formed on a sample, said method comprising the steps of:
- generating a probe beam of radiation from a coherent light source;
- focusing the probe beam substantially normal onto the aperiodic structure to create a spread of angles of incidence that extends from the normal to at least sixty degrees;
- monitoring the light from the probe beam diffracted from the structure along two orthogonal axes and generating an output that integrates the intensity of the rays having different angles of incidence that extends from the normal to at least sixty degrees;
- and
- evaluating the geometry of the structure based on the output signals using an analysis which treats the structure as being aperiodic.
Dependencies are inferred from the claim text.