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45-Degree Aperture Pair for E-Beam Spot Shaping

IP.com Disclosure Number: IPCOM000049710D
Original Publication Date: 1982-Jul-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 3 page(s) / 40K

Publishing Venue

IBM

Related People

Davis, DE: AUTHOR

Abstract

This aperture pair allows the generation of both horizontally - and vertically terminated 45(degrees) pattern segments in addition to rectangles in a single, straightforward fashion. It requires minimum offset voltage to do so and is superior to other methods.

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45-Degree Aperture Pair for E-Beam Spot Shaping

This aperture pair allows the generation of both horizontally - and vertically terminated 45(degrees) pattern segments in addition to rectangles in a single, straightforward fashion. It requires minimum offset voltage to do so and is superior to other methods.

Scanning electron(E)-beam lithography tools are going to use variable spot shaping in pattern writing. This concept increases throughput and avoids double exposures of certain pattern segments. Commonly used is the dual aperture shaping method [1, 2, 3, 4. The apertures for this dual aperture method have been primarily either square or of a pentagon 33 shape. Although horizontal and vertical shapes can be written with no overlapping, neither type of aperture is ideal for a commonly desired pattern element, i.e., 45 degrees, or shape. The square aperture can only write the 45 degree elements as a staircase approximation of small rectangular shapes that is both imprecise and time consuming as it contains many small pattern elements. The pentagon shape can generate 45(degree) segments in a more efficient manner but cannot join these segments to vertical or horizontal pattern elements without some degree of undesirable overlapping that results in pattern blooming. A pair of six-sided shaping apertures that allow the writing of both rectangular and 45 degree pattern segments that can be terminated either vertically or horizontally is proposed.

Fig. 1 shows the aperture pair A and B used in the dual shaping method. Although the shapes would be as shown, the relative sizes of these apertures would be such that the image of the first shaping aperture A, when projected on the second shaping aperture B, has the same size.

Figs. 2, 3 and 4 illustrate how the various main pattern segments are formed. The rectangles and the 45(degree) segments are continuously e variable in width. The 45 degree segments can be both horizontally and vertically terminated, which represents an important advantage achievable with this aperture pair.

As an application example, Fig. 5 show...