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With the rapid progress of high-precision reticle process technology, trial production of 4M DRAM and 16M DRAM memory chips has already started, as has mass production of 1M DRAM chips. The progress of microlithographic technology that has made this possible has improved process resolution from l um to 0.5um and now to 0.2um to 0.3um. These advances are largely due to better pattern-forming steppers, which have been improved by turning lenses to high NA, using shorter wavelengths (such as the i-line instead of g-line), and use of the excimer laser. Improved materials and processes — better resist and developer, CEL (Contrast Enhanced Layer), a new multi-layer resist technology, and the spread of simulation technology — have all helped the development of submicron pattern technology. In the patterning of the stepper, the reticle is a negative. Reticle provide various magnification such as 10X, 5X, IX, but the 5X reticle is the current choice. The reticle is usually used to make CAD design data with electron beam exposure equipment but, for the submicron patterns as described above, the reticle requires a precision like master mask precision of +/- 0.1um, nil independent defect of 0.5um and intrusion and protrusion of less than 0.2um. In making reticle, a quartz glass substrate is generally used on which Cr is coated and exposed to electron beam. But because of the use of such easily chargeable materials as glass and resist, precision and position of pattern cannot be guaranteed. The present study is made from the standpoint of process technology to investigate charging prevention and heat in reticle making. Although many studies have been done on charging of resist in electron beam exposure, little progress has been made regarding mask processes. This is the reason for the present study of making high-precision reticles.
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