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Author: Admin | 2025-04-27
Focuses heavily on the ideas of chemoepitaxy and graphoepitaxy. In chemoepitaxy, brushes or molecules are grafted, or covalently bonded, to existing features on the target. These existing features would commonly be fabricated with a typical lithography/deposition/etch process. Graphoepitaxy then relies upon confinement created by the patterned features to self-assemble the block copolymer in a prescribed manner. This self-assembly is dictated by the phase diagram of the BCP system, the confinement, and the Flory-Huggins chi parameter. By altering the geometry, the ratio of the components in the BCP, or the chi value, it is possible to generate spheres, cylinders, gyroidal, or lamellae features in the self-assembled BCP. Selective chemical etches exist for the BCP components and various process flows have been proposed to utilize these behaviors for the formation of nanoscale features.DSA does have numerous integration challenges. One main concern is in regard to finding a BCP system with sufficiently high chi value. Self-assembled geometries are also highly sensitive to defects or geometry fluctuations which can produce, in some cases, geometries and patterns that fluctuate dramatically both laterally and in the thickness dimension.1.7.7.4 Electron Beam LithographyElectron beam lithography is occasionally touted as a replacement for optical lithography. This process scans a focused electron beam onto a photoresist covered surface to pattern features. The chief advantage of e-beam lithography is that sub-10 nm resolution is possible. Indeed, e-beam lithography is used to pattern the masks used in other forms of optical lithography. However, this comes at a severe cost in throughput. A modern stepper or scanner can process hundreds of wafers per hour, while an e-beam tool would require many hours to expose a single wafer which makes these systems impractical for high-volume manufacturing (HVM) use. Attempts to productize these systems for HVM manufacturing have been undertaken in the past with very limited success.1.8 Metalization and Contact FormationFabricated transistors require metal contacts and metal routing to form CMOS or VLSI circuitry. A modern CPU may contain more than 60 miles of metal wires within a package that is roughly the size of your thumbnail. This metal wiring distributes power, clock, and signal
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