Photomask correction method using composite charged particle beam, and device used in the correction method
View Patent ↗The object of the present invention is to provide a method for solving the problem of surface damage due to gallium ion irradiation that poses a problem when carrying out mask repair using currently established FIB techniques, and the problem of residual gallium, and to provide a device realizing this method. The device of the present invention has an electron beam lens barrel that can carry out processing, as well as an FIB lens barrel, provided inside the same sample chamber, which means that a mask repair method of the present invention, in correction processing to remove redundant sections such as a mask opaque defect, phase shift film bump defect or a glass substrate cut remnant defect, comprises a step of coarse correction by etching using a focused ion beam and a step of finishing processing using an electron beam, to remove surface damage due to gallium irradiation, and residual gallium.
1. A method of correcting a redundant defect in a mask using a composite charged particle beam device, comprising the steps of:
providing a composite charged particle beam device having a focused ion beam lens barrel for producing a focused ion beam and an electron beam lens barrel for producing an electron beam;
scanning an electron beam produced by the electron beam lens barrel over a mask having a redundant defect to acquire an image of the mask;
identifying the position of the redundant defect from the image;
carrying out coarse correction of the redundant defect by etching using a focused ion beam produced by the focused ion beam lens barrel; and
carrying out finishing correction of the coarsely corrected redundant defect by etching using an electron beam produced by the electron beam lens barrel.
2. A method of correcting according to claim 1 ; wherein the finishing correction is carried out while directing an etching assist gas to the coarsely corrected redundant defect being irradiated by the electron beam.
3. A method of correcting according to claim 1 ; wherein the redundant defect is an opaque defect; the coarse correction is carried out to completely remove the opaque defect while incidentally injecting ions of the focused ion beam into the mask; and the finishing correction is carried out to remove the injected ions from the mask.
4. A method of correcting according to claim 1 ; wherein the focused ion beam is comprised of gallium ions.
5. A method of correcting according to claim 1 ; further including the steps of detecting secondary ions generated during coarse correction of the redundant defect and, when the type of detected secondary ions changes, terminating the coarse correction.
6. A method of correcting according to claim 1 ; further including the steps of detecting secondary ions generated during coarse correction of the redundant defect and, when the type of detected secondary ions changes, terminating the coarse correction and automatically switching to finishing correction to repair damage to the mask that occurred during coarse correction.