Patent ID: 7015487

Claim:
A projection apparatus for imaging a pattern of a mask onto a substrate having a radiation sensitive layer by using a beam of charged particles, the mask comprising a membrane layer made of a first material, scattering regions forming the pattern and made of a second material scattering the charged particles more than the membrane layer, a plurality of straightly extending supporting struts spaced apart from one another and supporting the membrane layer together with the scattering regions, and at least one mark region, wherein the projection apparatus comprises: a beam shaping device for producing the beam of charged particles with a predetermined cross-section in a plane in which the mask extends; a deflector for scanning the cross-section of the beam of charged particles in the plane in which the mask extends along a predetermined path over the mask parallel to the direction into which the struts extend; a sensor for detecting, concurrently with the imaging of the pattern of the mask onto the substrate, a number of the charged particles impinging on the at least one mark region provided on the mask; and a controller responsive to a measuring signal dependent on the number of charged particles detected by the sensor and configured to control the deflector so as to reduce deviations from the predetermined path.