Until recent years, dimensional scaling allowed for the fabrication of smaller and faster devices with increasing capacity. Currently, the limited area and the high density of the features in such devices have made self-aligned contacts/vias (SAC or SAV) a standard technique to overcome the decreasing distance between electrically functional elements in integrated circuits. In SAV schemes, the use of hard masks to define the effective transferred patterns allows for more relaxed via patterning conditions and overlay requirements. In this work, we explore a DSA-based fully self-aligned vias (FSAV) flow to further improve on traditional SAV processes. We use directed self-assembly (DSA) of block copolymers (BCP) to generate topographic features between the metal lines, which in combination with SAV, extend the benefits of this method to both X-Y directions, while maximizing the distance between the contacts and the adjacent not-connected metal lines to avoid potential shorts, as shown in Figure 1. In order to achieve this, patterned metal and/or dielectric lines are selectively functionalized using homopolymer brushes, to form a 1:1 chemical nano-pattern of specific surface energy, such that, when a BCP layer is coated and annealed on these samples, each block will align to the metal (or dielectric) lines underneath, as shown on Figure 2. We subsequently use one of the blocks as a template to generate topographic features between the metal lines. In addition, different hard masks are characterized to find the optimal material for the current scheme. Finally, we define the design rules for integration of the proposed flow into electrical devices.
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