摘要:
A lithographic apparatus is calibrated by reference to a primary reference substrate. Using an apparatus which need not be the same as the one being calibrated, there is obtained an apparatus-specific fingerprint of the primary reference substrate. Using the same set-up there is then obtained an apparatus-specific fingerprint of a secondary reference substrate. The apparatus-specific fingerprint of the primary reference substrate is subtracted from the apparatus-specific fingerprint of the secondary reference substrate to obtain and store an apparatus-independent fingerprint of the secondary reference substrate. The secondary reference substrate and stored apparatus-independent fingerprint are subsequently used together in place of the primary reference substrate as a reference for the calibration of the lithographic apparatus to be calibrated. Initial set-up for a cluster of lithographic tools can be performed with less use of the costly primary reference substrate, and with less interruption to normal production. The initial set-up can be integrated with on-going monitoring and re-calibration of the apparatuses.
摘要:
A lithographic apparatus is calibrated by reference to a primary reference substrate. Using an apparatus which need not be the same as the one being calibrated, there is obtained an apparatus-specific fingerprint of the primary reference substrate. Using the same set-up there is then obtained an apparatus-specific fingerprint of a secondary reference substrate. The apparatus-specific fingerprint of the primary reference substrate is subtracted from the apparatus-specific fingerprint of the secondary reference substrate to obtain and store an apparatus-independent fingerprint of the secondary reference substrate. The secondary reference substrate and stored apparatus-independent fingerprint are subsequently used together in place of the primary reference substrate as a reference for the calibration of the lithographic apparatus to be calibrated. Initial set-up for a cluster of lithographic tools can be performed with less use of the costly primary reference substrate, and with less interruption to normal production. The initial set-up can be integrated with on-going monitoring and re-calibration of the apparatuses.
摘要:
A lithographic exposure process is performed on a substrate using a scanner. The scanner comprises several subsystems. There are errors in the overlay arising from the subsystems during the exposure. The overlay errors are measured using a scatterometer to obtain overlay measurements. Modeling is performed to separately determine from the overlay measurements different subsets of estimated model parameters, for example field distortion model parameters, scan/step direction model parameters and position/deformation model parameters. Each subset is related to overlay errors arising from a corresponding specific subsystem of the lithographic apparatus. Finally, the exposure is controlled in the scanner by controlling a specific subsystem of the scanner using its corresponding subset of estimated model parameters. This results in a product wafer being exposed with a well controlled overlay.
摘要:
A method produces at least one monitor wafer for a lithographic apparatus. The monitor wafer is for use in combination with a scanning control module to periodically retrieve measurements defining a baseline from the monitor wafer thereby determining parameter drift from the baseline. In doing this, allowance and/or correction can be to be made for the drift. The baseline is determined by initially exposing the monitor wafer(s) using the lithographic apparatus, such that the initial exposure is performed while using non-standard alignment model settings optimized for accuracy, such as those used for testing the apparatus. An associated lithographic apparatus is also disclosed.
摘要:
A lithographic apparatus operates by moving a substrate and a patterning device relative to each other in a sequence of movements such that a pattern is applied at a successive portions on the substrate. Each portion of the substrate is patterned by a scanning operation in which the patterning device is scanned through the radiation beam while synchronously scanning the substrate through the patterned radiation beam so as to apply the pattern to the desired portion on the substrate. An intrafield correction is applied during each scanning operation so as to compensate for distortion effects which vary during the scanning operation. The intrafield correction includes corrective variations of one or more properties of the projection system, and optionally out-of-plane movements of the patterning device and/or substrate table.
摘要:
A method controls a scanning function of a lithographic apparatus. A first alignment strategy is used. A monitor wafer is exposed to determine baseline control parameters pertaining to the scanning function. The baseline control parameters are periodically retrieved from the monitor wafer. Parameter drift is determined from the baseline control parameters. Corrective action is taken based on the determination. A production wafer is exposed using a second alignment strategy, different to the first alignment strategy. The corrective action is modified so as to be substantially closer to the correction that would have been made had the second alignment strategy been used in exposing the monitor wafer.
摘要:
A method produces at least one monitor wafer for a lithographic apparatus. The monitor wafer is for use in combination with a scanning control module to periodically retrieve measurements defining a baseline from the monitor wafer, thereby determining parameter drift from the baseline. In doing this, allowance and/or correction can be to be made for the drift. The baseline is determined by initially exposing the monitor wafer(s) using the lithographic apparatus to perform multiple exposure passes on each of the monitor wafer(s). An associated lithographic apparatus is also disclosed.
摘要:
System parameters are checked through self-assessment of a production wafer without a reference or a monitor wafer. In particular, exposure errors and substrate table positioning errors can be corrected for.
摘要:
A method controls a scanning function of a lithographic apparatus. A first alignment strategy is used. A monitor wafer is exposed to determine baseline control parameters pertaining to the scanning function. The baseline control parameters are periodically retrieved from the monitor wafer. Parameter drift is determined from the baseline control parameters. Corrective action is taken based on the determination. A production wafer is exposed using a second alignment strategy, different to the first alignment strategy. The corrective action is modified so as to be substantially closer to the correction that would have been made had the second alignment strategy been used in exposing the monitor wafer.
摘要:
System parameters are checked through self-assessment of a production wafer without using a reference or a monitor wafer. In particular, the wafer is exposed at different orientations, the data from which provides for the calibration of system parameters.