Abstract: A method of photomask inspection uses available technology in a novel fashion to detect defects on a photomask. The method involves inspecting a photomask using a modified microscope, image comparison software, and a CCD camera. The microscope is modified to view the photomask out of focus and at low magnifications. The photomask may be scanned at multiple focuses to implement the inspection. This image is then compared with a reference image, such as an image from another die or a database. Any discrepancies between the images indicate a defect in the photomask. Alternatively, the photomask is inspected using a low magnification, low NA objective in dark field image of the optical microscope.

Abstract: A method for repairing bump and divot defects in phase shifting masks is performed by first identifying the locations of defects. Then, whether the defect is in a phase shift well or non-phase shift area is determined. The mask is then coated with photoresist. The immediate area surrounding each defect to be repaired (depending upon whether the defect is in a phase shift well or non-phase shift area), is then exposed to ultraviolet light. Additional defects are then identified and corresponding areas of the resist exposed. The resist is then developed such that the defect areas are not covered by the resist. Then SOG (spin on glass) material is deposited in the defect areas. The thickness of the SOG material at the areas to be repaired is measured. The SOG material is then etched to the surface of the substrate, thereby repairing both bump and divot defects.

Abstract: A method of repairing defects on a MoSi phase shifting template such as a mask or reticle that includes the steps of directing an ultraviolet light source over region of the template that includes an opaque defect. Clear defects caused by the removal of the opaque defect in the template are then repaired by a focused ion beam (FIB). The template may be exposed to a strongly basic solution to remove ion stains produced by the FIB. According to this method, the defect is removed with high edge placement accuracy and high quality of geometry reconstruction.

Abstract: A method of repairing opaque defects on a phase shifting template such as a mask or reticle that includes the steps of directing a focused ion beam (FIB) to scan a small region including an opaque defect. By monitoring a change in the intensity of a secondary signal, the end of the etching process is detected, and the template is exposed to a strongly basic solution to remove ion stains and repair residue produced by the FIB sputtering process. Suitable bases include sodium hydroxide, potassium hydroxide, ammonium hydroxide, tetramethyl ammonium hydroxide, and the like. According to this method, an opaque defect is removed with high accuracy of edge placement and high quality of geometry reconstruction, and the phase shifting amount and the transmission of the opaque defect area are adjusted to their proper levels with high precision.

Abstract: A method and apparatus for calibrating the coordinate systems of photomask processing machines improves processing efficiency and the quality of resulting photomasks. A test pattern is printed on an unproductive area of the photomask. The test pattern is used to calibrate the coordinate system of each processing machine on which the photomask is mounted. Using the test pattern as a common reference point enables points located using one processing machine to be quickly and accurately found on a second processing machine. The test pattern is also used as a reference for other metrology measurements.

Abstract: A method for repairing bump and divot defects in phase shifting masks is performed by first identifying the locations of defects. Then, whether the defect is in a phase shift well or non-phase shift area is determined. The mask is then coated with photoresist. The immediate area surrounding each defect to be repaired (depending upon whether the defect is in a phase shift well or non-phase shift area), is then exposed to ultraviolet light. Additional defects are then identified and corresponding areas of the resist exposed. The resist is then developed such that the defect areas are not covered by the resist. Then SOG (spin on glass) material is deposited in the defect areas. The thickness of the SOG material at the areas to be repaired is measured. The SOG material is then etched to the surface of the substrate, thereby repairing both bump and divot defects.

Abstract: A method of repairing quartz bump defects on an alternating phase shifting template such as a mask or reticle that includes the steps of locating a defect by either SEM scanning or low energy FIB scanning; directing a FIB at the bump defect, and irradiating the bump detect with high energy ions from the FIB. After the bump has been thoroughly stained with ions, the template is exposed to a strongly basic solution to remove the stained bump. Suitable bases include sodium hydroxide, potassium hydroxide, ammonium hydroxide, to tetramethyl ammonium hydroxide, and the like. According to this method, a quartz bump defect is removed with high precision and less damage to the substrate.

Abstract: A method and apparatus for calibrating the coordinate systems of photomask processing machines improves processing efficiency and the quality of resulting photomasks. A test pattern is printed on an unproductive area of the photomask. The test pattern is used to calibrate the coordinate system of each processing machine on which the photomask is mounted. Using the test pattern as a common reference point enables points located using one processing machine to be quickly and accurately found on a second processing machine. The test pattern is also used as a reference for other metrology measurements.

Abstract: A method of repairing clear defects on a template such as a mask or reticle that includes the steps of directing a focused ion beam (FIB) to fill the clear defect with a carbon film and directing a FIB in the presence of a water containing gas to remove the carbon halo from around the clear defect repair area. The end of the carbon halo removal process may be detected by monitoring a change in the intensity of a secondary signal. The template is exposed to a basic solution to remove ion stains produced by the FIB. According to this method, clear defects are repaired and the carbon halo formed around the clear defect repair area of the template are removed.

Abstract: A method and apparatus for calibrating the coordinate systems of photomask processing machines improves processing efficiency and the quality of resulting photomasks. A test pattern is printed on an unproductive area of the photomask. The test pattern is used to calibrate the coordinate system of each processing machine on which the photomask is mounted. Using the test pattern as a common reference point enables points located using one processing machine to be quickly and accurately found on a second processing machine. The test pattern is also used as a reference for other metrology measurements.