Methods and systems for clamping a substrate

#The disclosed embodiments relate to methods and systems for clamping a substrate to a support.

#In semiconductor lithography small structures are formed with high accuracy and reliability. In charged particle multiple beam lithography charged particles are directed onto the surface of a target, typically a wafer, to form patterns forming the basis of integrated circuits and components thereof. Such patterns usually comprise details within the nanometer range. In multiple beam lithography the pattern formed on the surface is determined by the position where each beam interacts with the resist on the surface. Lithography generally involves exposures of multiple subsequent layers, so that features formed in subsequent layers may be connected to create integrated circuits. Therefore, not only a pattern within one layer has to meet the required accuracy, but a pattern exposed in a subsequent exposure session has to be aligned with the one or more patterns created in previous exposure sessions in a sufficiently accurate manner.

#This requires a highly accurate and stable positioning of the substrate during processing, in particular during lithographic patterning.

#Embodiments will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

#FIG. 1 shows a conceptual illustration of a substrate clamped to a support according to embodiments of the present disclosure;

#FIG. 2 shows a schematic illustration of a distribution of adhesive material forming support locations according to embodiments of the present disclosure;

#The figures are intended for illustrative purposes only, and do not serve as restriction of the scope or the protection as laid down by the claims.

#FIG. 1 illustrates a cross section of a clamp 1 comprising a substrate 2 clamped to a support 4 by means of adhesive material 6. The substrate 2 is typically a semiconductor substrate, such as a silicon wafer, whereby the support 4 may be referred to as wafer table. The support 4 comprises a first surface 8 defining a plane 10, also referred to as support plane. The substrate 2 is supported on the first surface 8 via the adhesive material 6, which forms a plurality of support locations.

#When clamped the substrate extends within a second plane 12, referred to substrate plane, substantially parallel to the support plane 10. The plane 10 defined by the first surface and the adhesive material 6 provided thereon enables the substrate to be clamped such as to be substantially flat within the substrate plane 12. The support locations are arranged such that the substrate does not sag under its own weight, and such as to allow thermal expansion of the substrate within the plane.