Phase mask for projection lithography and method for the manufacture thereof
AssigneeSiemens Aktiengesellschaft
InventorsChristoph Noelscher, Leonhard Mader
Life of this patent
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Abstract
A carrier of light-transmissive material has a mask pattern of light-absorbent material arranged thereon. The carrier comprises first regions and second regions that are not covered by the absorbent material. An optical thickness of the carrier in the first regions differs from an optical thickness in the second regions such that a phase difference of 180.degree..+-.60.degree. exists between light that has traversed the first regions and light that has traversed the second regions. For manufacturing the phase mask, the first regions are produced by isotropic etching of the light-absorbent material and the second regions are produced by anisotropic etching into the carrier.
Claims11
A method for manufacturing a phase mask for projection photolithography having at least a first region and a second region wherein light of wavelength .lambda. which has passed through the first and second regions are phase-shifted by 180.degree..+-.60.degree. relative to one another, comprising the steps of:
- providing a carrier of light-transmissive material with a light-absorbing layer and with a photoresist layer;
- structuring the photoresist layer by mask lithography, and then producing the first region by isotropic etching of the light-absorbing layer down onto a surface of the carrier, an under-etching beneath the structured photoresist layer being produced in the isotropic etching of the light-absorbing layer;
- and
- producing the second region by anisotropic etching of the carrier to a depth d=.lambda.(1.+-.1/3)/(2(n.sub.2 -n.sub.1), where n.sub.2 is a refractive index in the first region and n.sub.1 is a refractive index of a surrounding medium, the anisotropic etching occurring in edge alignment with the structured photoresist layer.
A method for manufacturing a phase mask for projection photolithography having at least a first region and a second region wherein light of wavelength .lambda. which has passed through the first and second regions are phase-shifted by 180.degree..+-.60.degree. relative to one another, comprising the steps of:
- providing a carrier of light-transmissive material with a light-absorbing layer and with a photoresist layer;
- structuring the photoresist layer by mask lithography, and then producing a first opening and the first region by isotropic etching of the light-absorbing layer down onto a surface of the carrier;
- covering the first region with a further, structured photoresist layer;
- producing the second region by anisotropic etching of the carrier through said first opening to a depth d=.lambda.(1.+-.1/3)/(2(n.sub.2 -n.sub.1)), where n.sub.2 is a refractive index in the first region and n.sub.1 is a refractive index of a surrounding medium;
- and
- removing the further photoresist layer at said first region.
A method for manufacturing a phase mask for projection photolithography having at least a first region and a second region wherein light of wavelength .lambda. which has passed through the first and second regions are phase-shifted by approximately 180.degree. relative to one another, comprising the steps of:
- providing a carrier of light-transmissive material with a non-light transmissive layer and with a photoresist layer;
- structuring the photoresist layer, and then producing the first region by etching of the light-absorbing layer down onto a surface of the carrier, an under-etching beneath the structured photoresist layer being produced in the isotropic etching of the light-absorbing layer;
- and
- producing the second region by etching of the carrier to a depth d=.lambda.(1.+-.1/3)/(2(n.sub.2 -n.sub.1)), where n.sub.2 is a refractive index in the first region and n.sub.1 is a refractive index of a surrounding medium, the etching occurring in edge alignment with the structured photoresist layer.
A method for manufacturing a phase mask for projection photolithography having at least a first region and a second region wherein light of wavelength .lambda. which has passed through the first and second regions are phase-shifted by approximately 180.degree. relative to one another, comprising the steps of:
- providing a carrier of light-transmissive material with a non-light transmissive layer and with a photoresist layer;
- structuring the photoresist layer, and then producing a first opening and the first region by etching of the light-absorbing layer down onto a surface of the carrier;
- covering the first region with a further, structured photoresist layer;
- producing the second region by etching of the carrier through said first opening to a depth d=.lambda.(1.+-.1/3)/(2(n.sub.2 -n.sub.1)), where n.sub.2 is a refractive index in the first region and n.sub.1 is a refractive index of a surrounding medium;
- and
- removing the further photoresist layer at said first region.
Dependencies are inferred from the claim text.