Pattern fidelity improvement of DSA hole patterns

Abstract

Directed Self-Assembly (DSA) has been reported many times in the past decade as a technique for forming fine patterns^{1- 12}. As processes for application to the semiconductor process, the grapho-epitaxy process forms a desired pattern in an isolated area using a physical guide, and the chemical-epitaxy process forms a single pitch over a wide range using a chemical guide are typical. There are many reports regarding the line pattern formation using a lamellar phase to meet the demand for miniaturization from the mass production of semiconductors, and this is partly because the lamellar phase is relatively stable. However, for fine line pattern formation, multiplication techniques such as SADP (self-aligned double patterning) and SAQP (self-aligned quadruple patterning) have matured, and in recent years, the number of cases where EUV (extreme ultra-violet) single exposure is used is increasing. For this reason, DSA is rarely used in mass production of semiconductors. On the other hand, when miniaturizing high-density hole patterns, methods such as multiple exposure and etching, and methods of forming holes by crossing line patterns formed by SADP are relatively expensive. In addition, it is difficult to maintain the uniformity of hole CD (critical dimension) and pitch. In addition, when EUV is applied, it is not easy to suppress defects and form a wide range of patterns due to stochasticity, which has become a problem in recent years. Therefore, the formation of high-density hole patterns using DSA is attracting attention. In DSA, the hole diameter can be controlled by the molecular weight of BCP (block co-polymer), and the pitch tends to be uniform spontaneously. Also, if the chemical-epitaxy process is used, the pattern can be formed over a wide range. However, hole patterns using a cylinder phase tend to have large fluctuations in hole diameter and placement due to the high degree of freedom in placement. It is also important to what extent the established process can be extended to further miniaturization. In this presentation, we report on the hole pattern formation method by the chemo-epitaxy method and efforts to improve the fidelity for application to the semiconductor process.