No abstract

A joint Motorola/IBM experiment was performed in mix-and-match lithography across widely separated locations. A simple pattern placement metrology data set was created, and x-ray masks were manufactured according to this data at the IBM Advanced Mask Facility in Burlington, VT. The same data was converted into a 5x reticle and optically stepped on wafers at the Motorola Advanced Product R&D Lab in Austin, TX. The x-ray mask was designed to print upon two optical fields with one x-ray exposure. The x-ray mask was aligned to the wafers at the IBM Advanced Lithography Facility in East Fishkill, NY, to produce box-in-box images for overlay metrology.The main overlay problems encountered were systematic offsets between xray and optical images, and average magnification error of -8 ppm. The magnification error is substantial because of the 3°C temperature difference between the optical stepper stage and the x-ray mask-writer. In an actual device run, the magnification differences will be removed by compensation in the e-beam writing of the x-ray mask. Offsets will be removed by use of a send-ahead wafer to determine the correct offset alignment in the x-ray stepper. It should then be possible to obtain excellent overlay on both of the paired optical fields, since the optical tool is blind-stepping a very reliable grid.

A commercially available positive photoresist, Polychrome 129 SF, has been evaluated as both a positive electron beam resist and photoresist. The photoresist sensitivity, measured uniquely for a given developer based upon image dimensional control, is determined to be less than that of AZ 1350, under as nearly equivalent conditions as possible.The E -beam resist sensitivity is lower than that of PMMA reference, but the resist possesses good resolution.Near vertical edge wall profiles are obtained for 1-micrometer lines, but no undercutting is ever achieved regardless of electron charge density magnitude.The resist is capable of submicron line and space E -beam resolution, and 0.50 -0.75 micrometer wide isolated line patterns can be routinely achieved.

No abstract

No abstract