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Fixed Gap for Proximity Printing

IP.com Disclosure Number: IPCOM000078754D
Original Publication Date: 1973-Mar-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Forslund, DC: AUTHOR

Abstract

This arrangement provides a fixed gap between a semiconductor wafer and a photographic mask for proximity printing. As shown in Fig. 1 a photolithographic mask 1 is carried by mask support 2, which has a circular hole 3 to allow exposure light 4 to pass to and through the mask, then through the stretched thin-optical film 5 (such as nylon) to the semiconductor wafer 6. The wafer is carried by pedestal 7. Exposure takes place when the mask and thin-optical film are in contact with the reference plane 8 and the wafer is in contact with the thin film.

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Fixed Gap for Proximity Printing

This arrangement provides a fixed gap between a semiconductor wafer and a photographic mask for proximity printing. As shown in Fig. 1 a photolithographic mask 1 is carried by mask support 2, which has a circular hole 3 to allow exposure light 4 to pass to and through the mask, then through the stretched thin-optical film 5 (such as nylon) to the semiconductor wafer 6. The wafer is carried by pedestal 7. Exposure takes place when the mask and thin-optical film are in contact with the reference plane 8 and the wafer is in contact with the thin film.

The thin film is dispensed from a feed roll 9 which is housed in a dust proof enclosure 10, which is attached to the movable mask support 2. Take up roll 11 is also attached to the mask support.

The thin film is stretched evenly by a preloading on the feed rollers and by suitable tensioning mechanisms 12 and 13.

The object of this device is to protect the mask from damage by wafer contaminants and protrusions. By sandwiching the film between the wafer and mask, contaminants are picked up and are removed by rolling in a new sheet section for the alignment and exposure operations.

Thin films having an index of refraction near that of glass, the emulsion and photoresist create a shorter effective optical path length than that of air, with subsequent higher print resolution.

A second means of obtaining the objective is to employ a pellicle shown in Fig. 2. This pellicle is constructed of tw...