Abstract: For irradiating a target with a charged-particle beam, a plurality of stripes are written using the beam at respective stripe locations (y0-y15). In order to reduce charging effects during irradiation, the time sequence of the stripes, expressed as a function y(k) of a time index k, is different from a direct linear order. Based on a pre-determined integer number w (“stripe wing number”) which is not larger than the number of stripes divided by at least 4, the time sequence for writing the stripe of location y(k) at time index k is rearranged so as to comply with the condition that the stripe at a location y(k) is at most w stripe locations before the stripe location yk and at most w stripe locations behind the stripe location yk, and/or between each pair of spatially directly neighboring stripes, at most 2w different stripes are written.

Abstract: A pattern writing method for charged-particle lithography apparatuses using an improved correction for thermal distortion of the substrate includes determining an exposure position where the beam impinges on the substrate and the power of the beam at the exposure position; calculating heating of the substrate at the exposure position, and calculating, for a plurality of locations over the substrate, and the thermal diffusion and radiative cooling; calculating, for the same or a reduced plurality of locations on the substrate, the positional change of the substrate due to thermal expansion; determining a displacement distance which compensates the positional change at the exposure position, updating the structure to be written by shifting the exposure position of the beam by said displacement distance, and writing the updated structures on the substrate with the beam. These steps are repeated as a function of time and/or varying exposure position of the beam substrate position.

Abstract: In order to compensate for undesired effects of varying elevation of a target with respect to a nominal target plane, during writing a desired pattern on the target in a charged-particle beam apparatus, the pattern is re-calculated in each of a number of segments of the target plane by: determining an elevation of the target in the segment from the nominal target plane; determining a local blur value which represents the actual value of blur corresponding to the elevation, with regard to a dependence of the blur upon the elevation of the target; calculating a convolution kernel which represents a point spreading function realizing a local blur value; and re-calculating a nominal exposure pattern by applying the kernel to the pattern. The convolution kernel corresponds to introducing an additional blur into the pattern in the segment, increasing the blur to a given target blur value which is uniform to all segments.

Abstract: A method for determining parameters of an imaging transfer function (point spread function) is presented. With regard to a model that describes the imaging transfer function including a number of model parameters, a test substrate is exposed and developed using a test pattern which comprises multiple sub-patterns that are based on the same sub-pattern template but with varying control width of a feature in the template, such as the width of a line or a distance between lines. On the test substrate, isofocal dose measurements are performed using the structures thus formed on a test substrate with varying control and imaging parameters. The isofocal dose thus determined are utilized to determine the model parameters of the imaging transfer function.

Abstract: A method for determining focal properties in a target beam field of a charged-particle multi-beam processing apparatus is presented, where the focal properties relate to aperture images formed by the beamlets at or near the target within this apparatus, such as height of focus, astigmatic length, or size of blur. By modifying an electrostatic voltage of a lens or another suitable operating parameter of the projection optics, the landing angles of the beamlets are tilted by a small tilting angle, causing a small displacement of the positions where the beamlets hit the target surface. Using the amounts of displacement and the change of landing angles a map is generated that describes a mapping from the change of landing angles to the amounts of displacement as a function of the position, for instance by using a best fit to a predefined model; this map is then used to extract the focal properties, which in turn can be used to correct for imaging errors in the processing apparatus.

Abstract: A pattern writing method for charged-particle lithography apparatuses using an improved correction for thermal distortion of the substrate includes determining an exposure position where the beam impinges on the substrate and the power of the beam at the exposure position; calculating heating of the substrate at the exposure position, and calculating, for a plurality of locations over the substrate, and the thermal diffusion and radiative cooling; calculating, for the same or a reduced plurality of locations on the substrate, the positional change of the substrate due to thermal expansion; determining a displacement distance which compensates the positional change at the exposure position, updating the structure to be written by shifting the exposure position of the beam by said displacement distance, and writing the updated structures on the substrate with the beam. These steps are repeated as a function of time and/or varying exposure position of the beam substrate position.

Abstract: A method for irradiating a target with a beam of energetic electrically charged particles, wherein the target comprises an exposure region where an exposure by said beam is to be performed, and the exposure of a desired pattern is done employing a multitude of exposure positions on the target. Each exposure position represents the location of one of a multitude of exposure spots of uniform size and shape, with each exposure spot covering at least one pattern pixel of the desired pattern. The exposure positions are located within a number of mutually separate cluster areas which are defined at respective fixed locations on the target. In each cluster area the exposure position are within a given neighboring distance to a next neighboring exposure position, while the cluster areas are separated from each other by spaces free of exposure positions, which space has a width, which is at least the double of the neighboring distance.

Abstract: In a charged-particle lithography apparatus, during writing a desired pattern, the duration of exposure slots is adapted to compensate for fluctuations of the particle beam. In the writing process the aperture images are mutually overlapping on the target so each pixel is exposed through a number of aperture images overlapping at the respective pixel, which results in an exposure of the respective pixel through an effective pixel exposure time, i.e.

Abstract: In order to compensate for undesired effects of varying elevation of a target with respect to a nominal target plane, during writing a desired pattern on the target in a charged-particle beam apparatus, the pattern is re-calculated in each of a number of segments of the target plane by: determining an elevation of the target in the segment from the nominal target plane; determining a local blur value which represents the actual value of blur corresponding to the elevation, with regard to a dependence of the blur upon the elevation of the target; calculating a convolution kernel which represents a point spreading function realizing a local blur value; and re-calculating a nominal exposure pattern by applying the kernel to the pattern. The convolution kernel corresponds to introducing an additional blur into the pattern in the segment, increasing the blur to a given target blur value which is uniform to all segments.

Abstract: In a charged-particle lithography apparatus, during writing a desired pattern, the duration of exposure slots is adapted to compensate for fluctuations of the particle beam. In the writing process the aperture images are mutually overlapping on the target so each pixel is exposed through a number of aperture images overlapping at the respective pixel, which results in an exposure of the respective pixel through an effective pixel exposure time, i.e.

Abstract: A rasterized exposure method implementing a position correction for edge positions to correct for a non-linear relationship between the position of a feature edge (dCD) of a pattern element boundary and the nominal position of the boundary as expressed through the dose of exposure (d) of the edge pixel is provided. The position correction includes: determining a position value of the edge position, determining a corrected position value based on the position value using a predefined non linear function, and modifying the pattern to effectively shift the pattern element boundary in accordance with the corrected position value. The non linear function describes the inverse of the relationship between a nominal position value (d), which is used as input value during exposure of the pattern, and a resulting position (dCD) of the pattern element boundary generated when exposed with the nominal position value.

Abstract: A method for re-calculating a pattern to be exposed on a target by means of a charged-particle multi-beam writing apparatus is presented. The pattern elements of a pattern, initially associated with a respective assigned dose, are recalculated in view of obtaining reshaped pattern elements which have a nominal dose as assigned dose. The nominal dose represents a predefined standard value of exposure dose to be exposed for pixels during a scanning stripe exposure within the multi-beam apparatus.

Abstract: In a rasterized exposure method, in order to correct for a non-linear relationship between the position of a feature edge (dCD) of a pattern element boundary and the nominal position of the boundary as expressed through the dose of exposure (d) of the edge pixel, a position correction for edge positions is employed. The position correction includes: determining a position value describing said edge position, determining a corrected position value based on the position value using a predefined non-linear function, and modifying the pattern to effectively shift the pattern element boundary in accordance with the corrected position value. The non-linear function describes the inverse of the relationship between a nominal position value (d), which is used as input value during exposure of the pattern, and a resulting position (dCD) of the pattern element boundary generated when exposed with said nominal position value.

Abstract: A method for irradiating a target with a beam of energetic electrically charged particles, wherein the target comprises an exposure region where an exposure by said beam is to be performed, and the exposure of a desired pattern is done employing a multitude of exposure positions on the target. Each exposure position represents the location of one of a multitude of exposure spots of uniform size and shape, with each exposure spot covering at least one pattern pixel of the desired pattern. The exposure positions are located within a number of mutually separate cluster areas which are defined at respective fixed locations on the target. In each cluster area the exposure position are within a given neighboring distance to a next neighboring exposure position, while the cluster areas are separated from each other by spaces free of exposure positions, which space has a width, which is at least the double of the neighboring distance.

Abstract: A method for re-calculating a pattern to be exposed on a target by means of a charged-particle multi-beam writing apparatus is presented. The pattern elements of a pattern, initially associated with a respective assigned dose, are recalculated in view of obtaining reshaped pattern elements which have a nominal dose as assigned dose. The nominal dose represents a predefined standard value of exposure dose to be exposed for pixels during a scanning stripe exposure within the multi-beam apparatus.