Abstract: During a calculation technique, a modification to a reflective photo-mask is calculated. In particular, using information specifying a defect associated with a location on a top surface of the reflective photo-mask, the modification to the reflective photo-mask is calculated. For example, the calculation may involve an inverse optical calculation in which a difference between a pattern associated with the reflective photo-mask at an image plane in a photo-lithographic process and a reference pattern at the image plane in the photo-lithographic process is used to calculate the modification at an object plane in the photo-lithographic process. Note that the modification includes a material added to the top surface of the reflective photo-mask using an additive fabrication process. Moreover, the modification is proximate to the location.

Abstract: During a calculation technique, a modification to a reflective photo-mask is calculated. In particular, using information specifying a defect associated with a location on a top surface of the reflective photo-mask, the modification to the reflective photo-mask is calculated. For example, the calculation may involve an inverse optical calculation in which a difference between a pattern associated with the reflective photo-mask at an image plane in a photo-lithographic process and a reference pattern at the image plane in the photo-lithographic process is used to calculate the modification at an object plane in the photo-lithographic process. Note that the modification includes a material added to the top surface of the reflective photo-mask using an additive fabrication process. Moreover, the modification is proximate to the location.

Abstract: During a calculation technique, a modification to a reflective photo-mask is calculated. In particular, using information specifying a defect associated with a location on a top surface of the reflective photo-mask, the modification to the reflective photo-mask is calculated. For example, the calculation may involve an inverse optical calculation in which a difference between a pattern associated with the reflective photo-mask at an image plane in a photo-lithographic process and a reference pattern at the image plane in the photo-lithographic process is used to calculate the modification at an object plane in the photo-lithographic process. Note that the modification includes a material added to the top surface of the reflective photo-mask using an additive fabrication process. Moreover, the modification is proximate to the location.

Abstract: During a calculation technique, a modification to a reflective photo-mask is calculated. In particular, using information specifying a defect associated with a recessed area on a top surface of the reflective photo-mask, the modification to the reflective photo-mask is calculated. For example, the calculation may involve an inverse optical calculation in which a difference between a pattern associated with the reflective photo-mask at an image plane in a photo-lithographic process and a reference pattern at the image plane in the photo-lithographic process is used to calculate the modification at an object plane in the photo-lithographic process. Note that the modification includes a negative feature in which one or more pairs of layers in a multilayer stack in the reflective photo-mask are removed using a subtractive fabrication process. Moreover, the modification is proximate to the recessed area.

Abstract: A technique for determining a set of surface profiles in a multilayer stack during a fabrication process may be determined using a model of this fabrication process, a geometry of the multilayer stack (such as a pre-defined geometry of the multilayer stack) and a surface profile in the multilayer stack (such as a measured surface profile of the top surface or a bottom surface of the multilayer stack). For example, the model of the fabrication process may be based on a generalized Eikonal equation. In conjunction with deposition rates and/or physical properties of the layers in the multilayer stack, deposition or growth of the multilayer stack may be simulated. Based on the determined set of surface profiles, an acceptance condition of the multilayer stack (such as a multilayer stack in a photo-mask for use in extreme ultra-violet photolithography) may be determined and/or a remedial action may be recommended.

Abstract: A technique for inspecting, qualifying and repairing photo-masks for use at extreme ultra-violet (EUV) wavelengths is described. In this technique, multiple images of a substrate and/or a blank that includes multiple layers deposited on the substrate are measured and compared to identify first potential defects. Using information associated with the first potential defects, such as locations of the first potential defects, another image of the EUV photo-mask that includes a mask pattern defined in an absorption layer, which is deposited on top of the multiple layers, is measured. Based on the other image and the first potential defects, second potential defects in the EUV photo-mask are identified. Next, a qualification condition of the EUV photo-mask is determined based on the first potential defects and the second potential defects.