Method for applying back-exposure to embedded phase-shifting mask focused ion beam etching

Abstract

This invention provides one method to focus ion beam etching by use of imbed phase move mask mode, wherein, current process for MoSiOx mask imbed phase move mode is easy for pattern falling out problem which cannot be clear defined on quartz glass base materials outline and cannot be effectively removed by focus ion beam. This invention can accurately define deficiency area outline through negative resistant exposure to avoid above problems.

Description

technical field [0001] The invention relates to a mask process used in photolithography in the semiconductor industry, in particular to a method for manufacturing an embedded phase shift mask (EPSM) with a molybdenum silicide (MoSiOx) film. Background technique [0002] In the masking process of the semiconductor manufacturing process, in order to improve the lithography performance, the continuous demand for high-performance masks makes all aspects of the masking process must be revised and updated. In the current industry, most of the masks used are traditional chromium-baSed binary masks, or embedded phase-shift masks (EPSM, Embedded Phase-ShiftingMask) with molybdenum silicide (MoSiOx) films. ), the latter uses the principle of phase inversion interference of light waves for imaging, which has the advantages of strong optical imaging contrast and high exposure depth of field. [0003] For embedded phase shift masks, the main defect is that the pattern features formed by...

AI Technical Summary

Problems solved by technology

The boundary contour of the chromium film and the substrate quartz glass can be clearly distinguished by scanning electron microscopy. However, since the molybdenum-silicon phase shift layer has completely different chemical and physical properties from the traditional chromium binary mask layer, the focused ion beam The manufactured secondary ion analysis is difficult to accurately identify the molybdenum-silicon oxide film and quartz glass, so for the embedded phase shift mask of the molybdenum-silicon oxide film, the defect profile with high contrast cannot be obtained under the focused ion beam, and another On the one hand, the scanning electron microscope image itself can only get a clear outline of the surface with obvious height difference, but cannot get a clear outline of the thin residual film on the edge. image 3 A scanning electron microscope image obtained by scanning the mask surface with a focused ion beam is shown, Figure 4 On the basis of it, the actual defect area under the optical lens is drawn with a white line, and it can be seen that there is a large error between the defined focused ion beam etching area and the actual defect area

If the focused ion beam etching area defined by the scanning electron microscope exceeds the actual defect area, the ion beam will damage the quartz glass and cause gallium contamination; if the focused ion beam etching area defined by the scanning electron microscope is smaller than the actual defect area, then use After focused ion beam treatment, some defects must still exist

[0004] Due to the limitations of the characteristics of the machines used in the industry, the above-mentioned problems are unavoidable when the current mask manufacturing process involves embedded phase-shift masks with molybdenum silicide (MoSiOx) films

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