Technology path-finding for directed self-assembly for via layers

Abstract

Directed Self Assembly (DSA) is a very promising patterning technology for the sub-7nm technology nodes, especially for via/contact layers. In the Graphoepitaxy type of DSA, a complementary lithography technique is used to print the guiding templates, where the Block Copolymer (BCP) phase-separates into regular structures. Accordingly, the design-friendliness of a DSA-based technology is affected by several factors: the complementary lithography technique, the legal guiding templates, the number of masks/exposures used to print the templates, the related design rules, the forbidden patterns (hotspots) and the characteristics of the BCP. Thus, foundries have a huge number of choices to make for a future DSA-based technology, affecting the design-friendliness and the cost of the technology. In this paper, we propose a framework for DSA technology path-finding, for via layers, to be used by the foundry as part of Design and Technology Co-optimization (DTCO). The framework optimally evaluates a DSA-based technology where an arbitrary lithography technique is used to print the guiding templates, possibly using many masks/exposures and provides a design-friendliness metric. The framework is used to evaluate technologies like DSA+193nm Immersion (193i) Lithography, DSA+Extreme Ultraviolet (EUV) and DSA+ Self-Aligned Double Patterning. For example, one study showed that one mask of EUV in a DSA+EUV technology can replace three masks of 193i in a DSA+193i technology.