Abstract: Methods and systems disclosed herein can measure thin film stacks, such as film on grating and bandgap on grating in semiconductors. For example, the thin film stack may be a 1D film stack, a 2D film on grating, or a 3D film on grating. One or more effective medium dispersion models are created for the film stack. Each effective medium dispersion model can substitute for one or more layers. A thickness of one or more layers can be determined using the effective medium dispersion based scatterometry model. In an instance, three effective medium dispersion based scatterometry models are developed and used to determine thickness of three layers in a film stack.

Abstract: A spectroscopic metrology system includes a spectroscopic metrology tool and a controller. The controller generates a model of a multilayer grating including two or more layers, the model including geometric parameters indicative of a geometry of a test layer of the multilayer grating and dispersion parameters indicative of a dispersion of the test layer. The controller further receives a spectroscopic signal of a fabricated multilayer grating corresponding to the modeled multilayer grating from the spectroscopic metrology tool. The controller further determines values of the one or more parameters of the modeled multilayer grating providing a simulated spectroscopic signal corresponding to the measured spectroscopic signal within a selected tolerance. The controller further predicts a bandgap of the test layer of the fabricated multilayer grating based on the determined values of the one or more parameters of the test layer of the fabricated structure.

Abstract: Methods and systems for performing optical, model based measurements of a small sized semiconductor structure employing an anisotropic characterization of the optical dispersion properties of one or more materials comprising the structure under measurement are presented herein. This reduces correlations among geometric parameters and results in improved measurement sensitivity, improved measurement accuracy, and enhanced measurement contrast among multiple materials under measurement. In a further aspect, an element of a multidimensional tensor describing the dielectric permittivity of the materials comprising the structure is modelled differently from another element. In a further aspect, model based measurements are performed based on measurement data collected from two or more measurement subsystems combined with an anisotropic characterization of the optical dispersion of the materials under measurement.

Abstract: The disclosure is directed to nondestructive systems and methods for simultaneously measuring active carrier concentration and thickness of one or more doped semiconductor layers. Reflectance signals may be defined as functions of active carrier concentration and thickness varying over different wavelengths and over different incidence angles of analyzing illumination reflected off the surface of an analyzed sample. Systems and methods are provided for collecting a plurality of reflectance signals having either different wavelengths or different incidence angle ranges to extract active carrier density and thickness of one or more doped semiconductor layers.

Abstract: The disclosure is directed to nondestructive systems and methods for simultaneously measuring active carrier concentration and thickness of one or more doped semiconductor layers. Reflectance signals may be defined as functions of active carrier concentration and thickness varying over different wavelengths and over different incidence angles of analyzing illumination reflected off the surface of an analyzed sample. Systems and methods are provided for collecting a plurality of reflectance signals having either different wavelengths or different incidence angle ranges to extract active carrier density and thickness of one or more doped semiconductor layers.

Abstract: Performing modulation spectroscopy by directing a probe beam and a pump beam at a strained semiconductor sample, modulating the pump beam, and reflecting the probe beam into a detector. The detector produces a direct current signal proportional to reflectance R of the probe beam and an alternating current signal proportional to the modulation of the reflectance ?R of the probe beam. Both R and ?R are measured at a multiplicity of probe beam photon energies, to provide a spectrum having at least one line shape. The spectrum is analyzed to measure energy differences between interband electronic transitions of the sample, and the strain of the sample is determined from the energy differences.

Abstract: In one embodiment, a modulation spectroscopy method comprises the steps of directing a probe beam and a pump beam at a sample, modulating the pump beam, and the probe beam is reflected from the sample into a detector. The sample may include a strained semiconductor. The detector may produce as output an electrical signal which comprises a large d.c. signal proportional to reflectance R of the probe beam and a small a.c. modulated signal at the modulation frequency proportional to the modulation of the reflectance ?R of the probe beam. Both the reflectance R of the probe beam and the modulation of the reflectance ?R of the probe beam are measured at a multiplicity of probe beam photon energies arising from different wavelengths of the probe beam, to provide a photoreflectance spectrum comprising at least one photoreflectance lineshape.