Ims Nanofabrication Gmbh

Ims Nanofabrication Ag

Christoph Spengler

Elmar Platzgummer

Wolf Naetar

Mattia Capriotti

Johannes Leitner

Gottfried Hochleitner

Markus Wagner

Stefan Eder-Kapl

Samuel Kvasnica

Werner Rupp

Stefan Gerhold

Hanns Peter Petsch

Dietmar Puchberger

Michael Haberler

Theodor Adaktylos

A fine-adjustable electromagnetic lens for a charged-particle optical apparatus comprises a magnetic circuit assembly including one or more ring magnets, and a sleeve insert of generally rotational symmetry around a longitudinal axis. The sleeve insert surrounds a passage opening extending along the longitudinal axis, and comprises several electrically conductive electrode elements configured to generate an electrostatic field within the passage opening. The ring magnets are arranged circumferentially around an inner yoke shell and surrounded by an outer yoke shell; the inner yoke shell in turn surrounds a central portion of the sleeve insert. The ring magnets are magnetized such that the two magnetic poles are oriented towards the inner and outer yoke shell, respectively. The inner and outer yoke shell together with the ring magnets form a magnetic circuit having at least one gap, in order to generate a magnetic field reaching inwards into the passage opening and spatially overlapping with the electrostatic field generated by the sleeve insert.

Electromagnetic lens

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.

Correction of blur variation in a multi-beam writer

In a writing process in a charged-particle multi-beam apparatus, a desired pattern is written onto a target wherein said desired pattern is provided as input pattern data (INPDAT) in a vector format and processed through a pattern data processing flow. A data preprocessing system receives the input pattern data (INPDAT) and preprocesses the input pattern data independently of the writing process, preferably in advance to it, using writing parameter data provided to the data preprocessing system, and writes the intermediate pattern data (IMDAT) thus obtained to a data storage. When a writing process is carried out using the apparatus, its writing control system reads the intermediate pattern data from the data storage, converts them into pattern streaming data (SBUF), and streams the pattern streaming data to the apparatus for writing the pattern to the target.

Pattern data processing for programmable direct-write apparatus

A charged-particle source for generating a charged-particle comprises a sequence of electrodes, including an emitter electrode with an emitter surface, a counter electrode held at an electrostatic voltage with respect to the emitter electrode at a sign opposite to that of the electrically charged particles, and one or more adjustment electrodes surrounding the source space between the emitter electrode and the counter electrode. These electrodes have a basic overall rotational symmetry along a central axis, with the exception of one or more steering electrodes which is an electrode which interrupts the radial axial-symmetry of the electric potential of the source, for instance tilted or shifted to an eccentric position or orientation, configured to force unintended, secondary charged particles away from the emission surface.

Charged-particle source

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.

Method for irradiating a target using restricted placement grids

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., the sum of durations of contributing exposure slots, and the exposure slot durations are adjusted by: The durations in step (iii) are calculated in accordance with a predetermined set of allowed durations, wherein at least one of the durations thus calculated is different from the other durations selected for said set of exposure slots.

Adapting the duration of exposure slots in multi-beam writers

A charged-particle source for emission of electrons or other electrically charged particles comprises, located between the emitter electrode having an emitter surface and a counter electrode, at least two adjustment electrodes; a pressure regulator device is configured to control the gas pressure in the source space at a pre-defined pressure value. In a first cleaning mode of the particle source, applying a voltage between the emitter and counter electrodes directs gas particles towards the counter electrode, generating secondary electrons which ionize particles of the gas in the source space, and electrostatic potentials are applied to at least some of the adjustment electrodes, generating an electric field directing the ionized gas particles onto the emitter surface.

Charged-particle source and method for cleaning a charged-particle source using back-sputtering

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.

Non-linear dose- and blur-dependent edge placement correction

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. For the pattern elements associated with an assigned dose deviating from the nominal dose, the pattern element is reshaped by determining a reshape distance from the value of the assigned dose using a predefined dose slope function forming a reshaped pattern element, whose boundary is offset with regard to boundary of the initial pattern element by an offset distance equaling said reshape distance, assigning the nominal dose to the reshaped pattern element, and replacing the pattern element by the reshaped pattern element.

Dose-related feature reshaping in an exposure pattern to be exposed in a multi beam writing apparatus

In a charged-particle multi-beam writing method a desired pattern is written on a target using a beam of energetic electrically charged particles, by imaging apertures of a pattern definition device onto the target, as a pattern image which is moved over the target. Thus, exposure stripes are formed which cover the region to be exposed in sequential exposures, and the exposure stripes are mutually overlapping, such that each area of said region is exposed by at least two different areas of the pattern image at different transversal offsets (Y). For each pixel, a corrected dose amount is calculated by dividing the value of the nominal dose amount by a correction factor (q), wherein the same correction factor (q) is used with pixels located at positions which differ only by said transversal offsets (Y) of overlapping stripes.

Advanced dose-level quantization of multibeam-writers

Method for computing an exposure pattern for exposing a desired pattern on a target in a charged-particle lithography apparatus, in which a particle beam is directed to and illuminates a pattern definition device comprising an aperture array composed of a plurality of blanking apertures through which said particle beam penetrates for writing said desired pattern by exposing a multitude of pixels within an exposure area on the target, said method taking into account a spatially dependent distortion of the target within the exposure area, with respect to dislocations transversal to the direction of the particle beam.

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Vienna, Austria

Christoph Spengler