Author: He Yi

Publisher:

Published: 2015

Total Pages:

ISBN-13:

For more than 50 years, the size of the semiconductor devices has been scaling by approximately a factor of two every 1.5-2 years. This has brought tremendous benefits for the industry including lower cost per transistor, more computing power and higher speed. However, it has been recently observed that the scaling of devices is approaching fundamental (i.e. atomic scale) and economic (i.e. cost per fabrication facility) limits, in large part because traditional lithography is facing substantial challenges for printing the shrinking features while maintaining a reasonable cost. In response to this urgent need, researchers are actively searching for alternative patterning approaches as the next generation lithography. Potential solutions such as extreme ultraviolet lithography, electron beam lithography, and multiple patterning lithography have attracted much attention from the lithography community. However, each one of these solutions has its own drawbacks, such as extremely high cost or low throughput. Among these solutions, block copolymer directed self-assembly (DSA) stands out due to its low cost, high throughput, well-controlled sub-20 nm features, and experimentally demonstrated potential to scale below 14 nm. Block copolymers are unique soft materials that can self-assemble through microphase separation into various periodic nanostructures such as cylinders, spheres and lamellas, driven by the incompatibility between the different blocks. The feature size of these nanostructures is dependent on the molecular weight of the block copolymers and therefore not limited by the same factors that limit optical lithography such as ultraviolet light wavelength. In addition, the self-assembly could be controlled by a simple thermal annealing process, which significantly reduces the cost and improves the throughput. Among all the varieties of nanostructures, the cylindrical self-assembled patterns are especially suitable for patterning contacts and vias in integrated circuits (ICs). This dissertation focuses on the application of block copolymer DSA for contact hole patterning in ICs. This work first demonstrates the flexible control of aperiodic DSA patterns using small physical guiding templates, using both experiments and computational simulations. This is followed by the first patterning example of memory and random logic circuit contacts using DSA. To enable practical technology adoption, I introduce an alphabet approach that uses a minimal set of small physical templates to pattern all contact configurations on integrated circuits. This work also illustrates, through experiments, a general and scalable template design strategy that links the DSA material properties to the technology node requirements. Last but not least, the dissertation introduces a method to reduce DSA defectivity by using sub-DSA-resolution Assist Features (SDRAFs).