Abstract: A method for focusing an object plane (42) through an objective (30) and an optical assembly (10), with which the method can be carried out, are disclosed. A geometric reference structure (21) is positioned in a plane (36) conjugate to a field plane (34) of the objective (30) and is imaged onto the object plane (42). The geometric reference structure (21) is illuminated with a light beam (24), which encloses a non-zero angle (?) with a normal direction (38) of the conjugate plane (36). Therefore a position (Y) of an image (22) of the geometric reference structure (21) in the object plane (42) depends on the signed distance (37) between the object plane (42) and the field plane (34), and correspondingly is evaluated for the determination of the focus position. The optical assembly (10) preferentially may be a metrology tool (100) for measuring structures (120) on masks (100), wherein the objective (30) is the measurement objective of the metrology tool (100).

Abstract: An image (30) of a disc-shaped object (100) is recorded, wherein the entire surface (100O) is captured with a plurality of fields (60). A difference image (31) is formed, by subtracting a reference from each field (60) of the surface (100O) of the disc-shaped object (100), and subject to a color transformation, wherein by a suitable choice of transformation signals in one channel are maximized, while at the same time undesired variations, caused by production, of the fields (60) are moved to a different channel. That combination of transformation and detection channel is chosen for which the largest number of pixels of a field (60) with the defect to be found are located outside the spread of the pixels of the respective field (60) on the surface (100O) of the respective disc-shaped object (100) from production and provide the largest signals for the defect.

Abstract: A device for determining the position of a structure on an object in relation to a coordinate system is disclosed. The object is placed on a measuring table which is movable in one plane, wherein a block defines the plane. At least one optical arrangement is provided for transmitted light illumination and/or reflected light illumination. The optical arrangement comprises an illumination apparatus for reflected light illumination and/or transmitted light illumination and at least one first or second optical element, wherein at least part of the at least one optical element extends into the space between the block and an optical system support. At least one encapsulation is provided, encapsulating at least one optical component of at least one optical arrangement and/or at least one optical element.

Abstract: An apparatus (1) for the optical inspection of wafers is disclosed, which comprises an assembly unit (10) which carries optical elements (30, 31, 32, 33) of at least one illumination path (3) for a bright field illumination and optical elements (50, 51, 52, 60, 61, 62, 70, 71, 72, 80, 81, 82) of at least one illumination path (5, 6, 7, 8) for a dark field illumination. The assembly unit (10) furthermore carries plural optical elements (91, 92, 93, 94, 95, 96, 97, 98, 99, 100) of at least one detection path (91, 92). An imaging optical element (32) of the at least one illumination path (3) for the bright field illumination (30), imaging optical elements (51, 61, 71, 81) of the at least one illumination path for the dark field illumination, and imaging optical elements (91, 95, 96) of the at least one detection path (9) are designed in such a way that all illumination paths (3, 5, 6, 7, 8) and all detection paths (91, 92) are telecentric.

Abstract: A method for the reproducible determination of the positions of structures (3) on a mask (2) is disclosed. A pellicle frame (30) is firmly attached to the mask (2). A theoretical model of the bending of the mask (2) with the firmly attached pellicle frame (30) is calculated, wherein material properties of the mask (2), of the pellicle frame (30), and of the attaching means between the pellicle frame (30) and the mask (2) are taken into account in the calculation of the bending of the mask (2). For the calculation of the bending of the mask (2) its contact with three support points is considered. The positions of the structures (3) on the mask (2) are measured with a metrology tool (1). The measured positions of each structure are corrected with the theoretical model of the bending of the mask at the position of the respectively measured structure.

Abstract: A metrology tool (1) for measuring the positions of structures (32) on a mask surface (31) is disclosed. On a measuring stage (33) a reflector (36) selective with respect to the wavelength is provided, which essentially reflects light within a first wavelength region emitted from a first illumination device (10), and essentially does not reflect light within a second wavelength region emitted from a second illumination device (20). The reflector (36) selective with respect to the wavelength preferentially is a dichroic mirror. By detecting the light within the first wavelength region reflected by the reflector (36) the position of predefined sections of outer edges (37) of the mask is determined. The light from the second wavelength region is used for determining the coordinates of structures on the mask.

Abstract: An image (30) of a disc-shaped object (100) is recorded, wherein the entire surface (100O) is captured with a plurality of fields (60). A difference image (31) is formed, by subtracting a reference from each field (60) of the surface (100O) of the disc-shaped object (100), and subject to a color transformation, wherein by a suitable choice of transformation signals in one channel are maximized, while at the same time undesired variations, caused by production, of the fields (60) are moved to a different channel. That combination of transformation and detection channel is chosen for which the largest number of pixels of a field (60) with the defect to be found are located outside the spread of the pixels of the respective field (60) on the surface (100O) of the respective disc-shaped object (100) from production and provide the largest signals for the defect.

Abstract: A method for the reproducible determination of the positions of structures (3) on a mask (2) is disclosed. A pellicle frame (30) is firmly attached to the mask (2). A theoretical model of the bending of the mask (2) with the firmly attached pellicle frame (30) is calculated, wherein material properties of the mask (2), of the pellicle frame (30), and of the attaching means between the pellicle frame (30) and the mask (2) are taken into account in the calculation of the bending of the mask (2). For the calculation of the bending of the mask (2) its contact with three support points is considered. The positions of the structures (3) on the mask (2) are measured with a metrology tool (1). The measured positions of each structure are corrected with the theoretical model of the bending of the mask at the position of the respectively measured structure.

Abstract: A method for focusing an object plane (42) through an objective (30) and an optical assembly (10), with which the method can be carried out, are disclosed. A geometric reference structure (21) is positioned in a plane (36) conjugate to a field plane (34) of the objective (30) and is imaged onto the object plane (42). The geometric reference structure (21) is illuminated with a light beam (24), which encloses a non-zero angle (?) with a normal direction (38) of the conjugate plane (36). Therefore a position (Y) of an image (22) of the geometric reference structure (21) in the object plane (42) depends on the signed distance (37) between the object plane (42) and the field plane (34), and correspondingly is evaluated for the determination of the focus position. The optical assembly (10) preferentially may be a metrology tool (100) for measuring structures (120) on masks (100), wherein the objective (30) is the measurement objective of the metrology tool (100).

Abstract: A metrology tool (1) for measuring the positions of structures (32) on a mask surface (31) is disclosed. On a measuring stage (33) a reflector (36) selective with respect to the wavelength is provided, which essentially reflects light within a first wavelength region emitted from a first illumination device (10), and essentially does not reflect light within a second wavelength region emitted from a second illumination device (20). The reflector (36) selective with respect to the wavelength preferentially is a dichroic mirror. By detecting the light within the first wavelength region reflected by the reflector (36) the position of predefined sections of outer edges (37) of the mask is determined. The light from the second wavelength region is used for determining the coordinates of structures on the mask.

Abstract: A metrology system (1) and a method for determining low order errors are disclosed. At least one measurement objective (9) for the determination of the position of structures (3) on a substrate (2) is provided. The substrate (2) to be measured rests in a support on three points of support (52). The support exhibits an opening (53) for measuring the substrate (2). At least two marks (54) are provided on the support for the mask (2) in such a way that the marks (54) are capturable with the measurement objective (9) by moving the measurement table (20). Furthermore the substrate (2) in the support does not screen the marks (54) on the support.

Abstract: An apparatus (1) for the optical inspection of wafers is disclosed, which comprises an assembly unit (10) which carries optical elements (30, 31, 32, 33) of at least one illumination path (3) for a bright field illumination and optical elements (50, 51, 52, 60, 61, 62, 70, 71, 72, 80, 81, 82) of at least one illumination path (5, 6, 7, 8) for a dark field illumination. The assembly unit (10) furthermore carries plural optical elements (91, 92, 93, 94, 95, 96, 97, 98, 99, 100) of at least one detection path (91, 92). An imaging optical element (32) of the at least one illumination path (3) for the bright field illumination (30), imaging optical elements (51, 61, 71, 81) of the at least one illumination path for the dark field illumination, and imaging optical elements (91, 95, 96) of the at least one detection path (9) are designed in such a way that all illumination paths (3, 5, 6, 7, 8) and all detection paths (91, 92) are telecentric.

Abstract: The invention relates to a method of learning a knowledge-based database used in automatic defect classification. According to this method, the user is spared a series of entries as the system carries out an automatic learn mode, which requires a reduced number of user entries.