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Multicolumn Electron Beam Lithography (MEBL), a proprietary technology platform developed by Multibeam Corporation, is being applied to enable Security Lithography – a maskless embedding of unique security information into each IC during routine wafer fabrication. This paper focuses on ensuring Secure Chip ID, which provides traceability of a chip throughout its lifecycle and enables confirmation of its unique identity and provenance. The complete MEBL embedding process is disclosed – from chip design to IC fab to verification test. This paper also shows how MEBL hardcoding of the Secure Chip ID “at the silicon level” makes the embedding process cost-efficient and tamperproof.

Image contrast of line-cut and contact hole features patterned using Complementary E-Beam Lithography (CEBL) at advanced technology nodes are analyzed. The study assumes one beam in each column is used to pattern features less than 20 nm (Full Width Half Maximum, FWHM), consistent with Multibeam’s multi-column vector-scan approach for CEBL patterning. When the feature size approaches the resolution of the e-beam column design, the dose intensity profile follows a Gaussian model. Using Gaussian profiles, the image contrast of line cut or contact hole features can be studied as a function of beam FWHM size, spacing between features, and proximity effect. As expected, the image contrast was dominated by contact hole stepping distance (i.e., spacing between neighboring contact holes) and proximity effect. The plot of image contrast versus contact position becomes very useful in studying the impact of contact spacing, proximity effect and process window in writing line-cut or contact features in CEBL applications. Based on a given design rule of contact hole size and spacing, we can determine the appropriate e-beam size and resist contrast to achieve good image contrast. The relationship between resist contrast and image contrast is discussed to estimate the process window in CEBL applications. Finally, the impact of electron forward scattering in resist is analyzed, including the effects of resist thickness and beam voltage selections. We determined that the influence of back scattered electrons is not a significant factor in CEBL applications when feature pattern density is less than 11%.

Developers of e-beam lithography systems are pursuing diverse strategies to bolster throughput. To achieve parallelism, some e-beam efforts focus on building multiple-columns, and others focus on developing columns with multiple beamlets. In this paper, we discuss the benefits and throughput of a multiple column approach for a particular application: Complementary E-Beam Lithography (CEBL). CEBL is a novel approach where the e-beam lithography system is used only to pattern the smallest features. Everything else is patterned with existing optical lithography equipment. By working hand-in-hand with optical lithography, CEBL provides an urgently needed solution to create next-generation microchips. Moreover, CEBL is extendable for multiple technology generations. We show how a multiple column approach is the best way to meet the requirements for CEBL, including high throughput, high resolution and overlay accuracy, without excess complexity or cost.

193nm Optical lithography has powered the industry's growth for the last 10 years and multiple patterning is poised to extend 193nm even further. There is a growing trend in Logic design for manufacturing, with high-volume manufacturing (HVM) firms adopting a layout style using unidirectional single-pitch straight lines in poly and metal layers. These layouts lend themselves to a complementary lithography approach. First, unidirectional lines are patterned with Optical lithography. Second, these lines are "cut" to form the desired layout. In this paper, we present EBDW as a complement to optical lithography for line-cutting. We show how e-beam multiple-column architecture, optimized for line-cutting, is the best for patterning critical layers at advanced nodes as Complementary Lithography.