Asml Netherlands B.v.

Asm Lithography B.v.

Cornelis J Van Der Laan

Josephus J M Braat

A plate with substantially constant thickness is used to compensate for the residual distortion in the image projected by a high-quality projection lens for lithography. The two surfaces of the plate have an identical aspherical profile, whose shape has been calculated using the measured distortion map of the lithographic objective. The figuring process applied to the plate uses the principle of polishing in the presence of an elastic deformation, so as to achieve the desired aspherical shape on both sides.

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Maasluis, Netherlands

Cornelis J Van Der Laan