Abstract: An e-beam lithographic system capable of in situ registration. The system has an optics section such as a VAIL lens. A controllable stage moves a substrate with respect to the beam axis to place substrate writing fields beneath the beam. A field locking target between the optics section and the stage has an aperture sized to permit the beam to write a target field on the substrate. The field locking target includes alignment or registration marks around the aperture. A differential interferometric system measures the relative positions of the field locking target and the stage and controls stage position. The beam patterns the substrate on a field by field basis. As the stage is moving into position for each field, the beam is swept until it hits the alignment marks, thereby checking system alignment. The beam control data, i.e., coil currents necessary to hit the marks are stored, and drift correction values calculated from the beam control data.

Abstract: An e-beam lithographic system capable of in situ registration. The system has an optics section such as a VAIL lens. A controllable stage moves a substrate with respect to the beam axis to place substrate writing fields beneath the beam. A field locking target between the optics section and the stage has an aperture sized to permit the beam to write a target field on the substrate. The field locking target includes alignment or registration marks around the aperture. A differential interferometric system measures the relative positions of the field locking target and the stage and controls stage position. The beam patterns the substrate on a field by field basis. As the stage is moving into position for each field, the beam is swept until it hits the alignment marks, thereby checking system alignment. The beam control data, i.e., coil currents necessary to hit the marks are stored, and drift correction values calculated from the beam control data.

Abstract: An e-beam system for making masks corrects the beam for pattern-dependent errors by executing the bulk of the post-processing program only once, with two sets of output data being generated by the encode routine. A first output file of the encode routine generates the beam control data without pattern-dependent corrections. A second output file merges the beam control data with the data for metrology marks. A test wafer is patterned using the second output file and measured to generate a set of pattern correction data. Production wafers are written using the beam control data corrected on the fly by the pattern correction data.

Abstract: Process steps are provided to analyze image placement on a pre-distorted lithographic mask produced by a lithographic system. Obtain metrology data, form a reference array equal to the design coordinates of the metrology sites. Align the metrology data grid coordinate system to remove rigid body components from the metrology data offsets. Parse the metrology data into one or more correction areas. If the mask is to have its disposition provided according to the statistics of the residual errors in the correction areas, then compute the statistics and compare them to the specifications. Otherwise concatenate the local reference arrays summed with their corresponding correction area center coordinates to form reference mark design location arrays. Concatenate temporary arrays with the mask offsets free of pre-distortion into an array of mask offsets corresponding to desired disposition areas and compute statistical distribution of residual errors in array(s) of mask offsets for disposition.

Abstract: A digitally stepped deflection raster system and a method of operation thereof are disclosed. The digitally stepped deflection raster system operates to provide horizontal and vertical scans of an area of interest. The total length of each of the horizontal and vertical scans is proportioned into segments to provide non-continuous scanning signals that are arranged into predetermined raster patterns each of which reduces the deflection placement error of the digitally stepped deflection raster system.

Abstract: A method is disclosed for improving the electron beam apparatus lithography process wherein the calibration procedure for the apparatus is improved by using the product pattern and stepping sequence used to make the mask on a calibration plate and/or calibration grid and to determine improved apparatus correction errors which errors are used to control the apparatus for making an improved mask. The well-known EMULATION procedure is improved by calculating additional field correction errors based on a two step registration procedure to determine X/Y apparatus stepping errors. The LEARN procedure based on a static calibration grid procedure is improved by employing the duty cycle of the product pattern to calibrate the apparatus to determine deflection beam errors.

Abstract: A method for correcting placement errors in a lithography system, and a system therefor, are disclosed. The method comprises the steps of obtaining metrology data of sufficient density to smoothly map an error to be corrected, deriving a metrology data grid coordinate system from the data, aligning the metrology data grid coordinate system to remove rigid body components, and for each of a plurality of lithographic fields: identifying a number of metrology sites nearest to the center of the field; establishing a reference grid coordinate system coinciding with the lithographic field; determining at least one correction factor which minimizes the residual errors; and applying at least one correction factor for at least one field to the first lithography system to correct a placement error. Such a method and system are particularly useful for error correction in e beam lithography tools.