Patent DE-102009016608-A1 (DE)
Title: Illumination optic for a microlithography projection exposure system for illuminating an object field with illumination light of a radiation source, comprises an optical beam forming element, and a group of beam formation sections
Inventor: FIOLKA DAMIAN
IPC: G03F7/20
Filed: 2009-04-08
Abstract: The illumination optic (5) comprises an optical beam forming element, a group of beam formation sections for producing a first beam angular distribution of the illumination light, a further group of beam forming sections for producing a further beam angular distribution of the illumination light that differs from the first beam angular distribution, an optical group control element for subjecting exactly one of the two groups of the beam forming sections of the optical beam formation element with the illumination light, and a beam diversion arrangement. The illumination optic (5) comprises an optical beam forming element, a group of beam formation sections for producing a first beam angular distribution of the illumination light, a further group of beam forming sections for producing a further beam angular distribution of the illumination light that differs from the first beam angular distribution, an optical group control element for subjecting exactly one of the two groups of the beam forming sections of the optical beam formation element with the illumination light, a beam diversion arrangement arranged before the beam formation element for the illumination light, and an expanding optical system for the illumination light before the control element. The beam diversion arrangement is transposable between scanning positions and distracts in each of the scanning position of the illumination light to one of the group of the beam formation section of the optical beam formation element, which is formed as diffractive optical element. The beam diversion arrangement is implemented so that a different wave angle of the illumination light results on the optical ray formation element. The groups of the optical beam formation element comprise elements for compensation of different angle of incidence. The compensation element is implemented as compensation wedge element. The beam diversion arrangement is implemented as a deflection mirror. The beam diversion arrangement is implemented so that an angle of incidence of the illumination light is independent on the optical beam formation element from the scanning position. The beam diversion arrangement comprises two opposite deflection mirrors. The beam diversion arrangement is implemented as lens shifting diagonal to the beam direction. The beam diversion arrangement comprises a polarization-rotating element that produces first and second polarization conditions of the illumination light in first and second polarization positions, a birefringent optical deflection element that is mounted downstream to the polarization-rotating element and distracts dependent on the polarization condition adjusted by the polarization-rotating element with different angle of deflection. The polarization-rotating element is subdivided into two polarization-rotating element areas and is revolved around an axis that passes parallel to the beam direction. The deflection element is formed as transverse prism from an optical crystal with an optical crystal axis that lies in the deflection plane of the illumination light. The beam diversion element is arranged between the control element and the optical beam formation element. The optical group control element is implemented as micro lens array. The beam formation section is guided vertical to the beam direction as rectangular sections with long and short length. The optical group control element is implemented as micro lens array with cylinder lens that is oriented parallel to the longitudinal side of the rectangular section of the beam formation sections. The beam formation element is subdivided vertical to beam direction of the illumination light in a first optical beam formation element area with two groups of beam formation sections and in a further beam formation element area with two groups of beam formation sections. The beam formation section groups produce the optical beam formation element area of the same illumination angle distribution. The beam diversion arrangement is subdivided into first diversion element that distracts a part of the illumination light on the first optical beam formation element area and into a further diversion element that distracts a further part of the illumination light on the further optical beam formation element area. The beam formation section of the different optical beam formation element area is arranged diagonal to the beam direction against each other. The diversion elements are actuated during shifting between the diversions positions in such a way that the position of the focal point does not change the illumination light. The illumination optic is implemented in such a way that the different illumination angle distributions are assigned respectively different linear polarization condition of the illumination light after the optical beam formation element. A polarization filter is arranged after the optical beam formation element and before the object field for the suppression of selected linear polarization condition of the illumination light. The polarization filter is arranged in the area of pupils plain of the illumination object and is subdivided vertically to the beam direction in quadrant. The polarization filter has a pyramid shape and the pyramid side walls are guided as dielectrically coated thin layer polarizations. The polarization filter is revolvably guided around an axis parallel to beam direction. The polarization rotation element is implemented as static rotor or as rotatable Lambda/2-plates. Independent claims are included for: (1) projection exposure system; and (2) method for the production of structured component.