Abstract: In systems and methods measure overlay error in semiconductor device manufacturing based on target image asymmetry. As a result, the advantages of using very small in-chip targets can be achieved, while their disadvantages are reduced or eliminated. Methods for determining overlay error based on measured asymmetry can be used with existing measurement tools and systems. These methods allow for improved manufacturing of semiconductor devices and similar devices formed from layers.

Abstract: A method for correlating a structural parameter of a plurality of gratings acquires images from a plurality of gratings, which have different structural parameters. A focus metrics algorithm is then performed to find the off-focus offset of the orders of each grating from the intensity variation of these images, and the variation ratio of the off-focus offset to the order for each grating is calculated later. Consequently, the structural parameters of these gratings can be correlated based on the variation ratio of the off-focus offset to the order. The present method acquires images from an unknown grating at different off-focus offsets, and performs a focus metrics algorithm to find the off-focus offset of the orders of the unknown grating. The variation ratio is calculated and the structural parameter of the unknown grating is determined based on the variation ratio.

Abstract: A method for correlating line width roughness of gratings first performs a step (a) generating a characteristic curve of a predetermined grating having a known line width, and a step (b) performing a comparing process to select a matching spectrum from a plurality of simulated diffraction spectrum of known line width, and setting the known line width of the matching spectrum as the virtual line width of the predetermined grating. Subsequently, the method performs a step (c) changing a measuring angle and repeating the steps (a) and (b) to generate a virtual line width curve, and calculating the deviation of the virtual line width curve. The method then performs a step (d) changing the line width roughness of the predetermined grating and repeating the steps (a), (b) and (c), and a step (e) correlating the line width roughness and the deviation of the virtual line width curve to generate a correlating curve.

Abstract: In an overlay metrology method used during semiconductor device fabrication, an overlay alignment mark facilitates alignment and/or measurement of alignment error of two layers on a semiconductor wafer structure, or different exposures on the same layer. A target is small enough to be positioned within the active area of a semiconductor device combined with appropriate measurement methods, which result in improved measurement accuracy.

Abstract: A method for correlating line width roughness of gratings first performs a step (a) generating a characteristic curve of a predetermined grating having a known line width, and a step (b) performing a comparing process to select a matching spectrum from a plurality of simulated diffraction spectrum of known line width, and setting the known line width of the matching spectrum as the virtual line width of the predetermined grating. Subsequently, the method performs a step (c) changing a measuring angle and repeating the steps (a) and (b) to generate a virtual line width curve, and calculating the deviation of the virtual line width curve. The method then performs a step (d) changing the line width roughness of the predetermined grating and repeating the steps (a), (b) and (c), and a step (e) correlating the line width roughness and the deviation of the virtual line width curve to generate a correlating curve.

Abstract: In an overlay metrology method used during semiconductor device fabrication, an overlay alignment mark facilitates alignment and/or measurement of alignment error of two layers on a semiconductor wafer structure, or different exposures on the same layer. A target is small enough to be positioned within the active area of a semiconductor device combined with appropriate measurement methods, which result in improved measurement accuracy.

Abstract: A method for inspecting a grating biochip comprises the steps of irradiating a grating biochip using a light beam, measuring a diffracted light using a photodetector, selecting a plurality of parameters of the grating biochip, and optimizing the parameters to enhance the detection sensitivity, wherein the diffracted light is generated by the light beam passing the grating biochip. The grating biochip comprises a grating structure including a semiconductor substrate, a grating positioned on the semiconductor substrate and a dielectric layer covering the grating and the semiconductor substrate. The sample of the biochip is positioned on the grating structure.

Abstract: A method for designing a grating comprises steps of (a1) generating a first diffraction spectrum based on calculation values of a plurality of structural parameters, (a2) calculating a first difference value between the first diffraction spectrum and a first nominal spectrum, (a3) setting a default difference value with the first difference value and default structural parameter values with the structural parameter values, (b1) changing one of the structural parameter values to generate a second diffraction spectrum, (b2) calculating a second difference value between the second diffraction spectrum and a second nominal spectrum, and (c) comparing the default difference value and the second difference value, updating a default difference value with the smaller one, and updating the default structural parameter values with the structural parameter values corresponding to the smaller one.

Abstract: A method of measuring dimensions for an optical system to measure the critical dimension of a sample object according to this aspect of the present invention includes the steps of preparing a plurality of standard objects, selecting a predetermined focus metric algorithm, performing an analyzing process on each standard object to generate a plurality of focus metric distributions using the predetermined focus metric algorithm, analyzing the focus metric distributions to determine a target order, generating a reference relation, acquiring a measured characteristic value from the sample object, and determining the critical dimension of the sample object based on the measured characteristic value and the reference relation. Each standard object has a grating-shaped standard pattern with a predetermined pitch and line width. The focus metric algorithm is a gradient energy method, a Laplacian method, a standard deviation method, or a contrast method.

Abstract: A method for inspecting a grating biochip comprises the steps of irradiating a grating biochip using a light beam, measuring a diffracted light using a photodetector, selecting a plurality of parameters of the grating biochip, and optimizing the parameters to enhance the detection sensitivity, wherein the diffracted light is generated by the light beam passing the grating biochip. The grating biochip comprises a grating structure including a semiconductor substrate, a grating positioned on the semiconductor substrate and a dielectric layer covering the grating and the semiconductor substrate. The sample of the biochip is positioned on the grating structure.

Abstract: In systems and methods measure overlay error in semiconductor device manufacturing based on target image asymmetry. As a result, the advantages of using very small in-chip targets can be achieved, while their disadvantages are reduced or eliminated. Methods for determining overlay error based on measured asymmetry can be used with existing measurement tools and systems. These methods allow for improved manufacturing of semiconductor devices and similar devices formed from layers.

Abstract: In an overlay metrology method used during semiconductor device fabrication, an overlay alignment mark facilitates alignment and/or measurement of alignment error of two layers on a semiconductor wafer structure, or different exposures on the same layer. A target is small enough to be positioned within the active area of a semiconductor device combined with appropriate measurement methods, which result in improved measurement accuracy.

Abstract: A system and method for efficiently and accurately determining grating profiles uses characteristic signature matching in a discrepancy enhanced library generation process. Using light scattering theory, a series of scattering signatures vs. scattering angles or wavelengths are generated based on the designed grating parameters, for example. CD, thickness and Line:Space ratio. This method selects characteristic portions of the signatures wherever their discrepancy exceeds the preset criteria and reforms a characteristic signature library for quick and accurate matching. A rigorous coupled wave theory can be used to generate a diffraction library including a plurality of simulated diffraction spectrums based on a predetermined structural parameter of the grating. The characteristic region of the plurality of simulated diffraction spectrums is determined based on if the root mean square error of the plurality of simulated diffraction spectrums is larger than a noise level of a measuring machine.

Abstract: Precision in scatterometry measurements is improved by designing the reticle, or the target grating formed by the reticle, for greater overlay measurement sensitivity. Parameters of the structure and material of the substrate are first determined. These parameters may include the material composition, thickness, and sidewall angles of the sample substrate. The target grating is then designed so that the overlay measurement, on the sample substrate, is made more sensitive. A suitable measurement wavelength is selected, optionally via computer simulation, to further improve the sensitivity. This method increases the change of reflective signatures with overlay offsets, and thus improves the sensitivity of overlay measurement.