Fluorinated Polymethacrylates as Highly Sensitive Non-chemically Amplified E-beam Resists

In an effort to improve upon the sensitivity of commercial non-chemically amplified e-beam resists, four polyacrylates functionalized with alpha-CF3 and/or CH2CF3 alkoxy substituents were studied. The alpha-CF3 substituent is known to increase backbone-scission efficiency while simultaneously eliminating acidic out-gassing and cross-linking known to occur in alpha-halogen substituted polyacrylates. Contrast curves for the polymeric alpha-CF3 acrylates, generated through e-beam exposure, showed the resists required an order of magnitude less dose than the current industry-standards, PMMA and ZEP. The fundamental sensitivity of these materials to backbone scissioning was determined via Co-60 gamma-ray irradiation. The chain scissioning, G(s), and cross-linking, G(x), values calculated from the resulting change in molecular weight demonstrated that all fluorinated resists possess higher G(s) values than either PMMA or ZEP and have no detectable G(x) values. Utilizing e-beam and EUV interference lithographies, the photospeed of PMTFMA was found to be 2.8x and 4.0x faster, respectively, than PMMA.Chemistr

Influence of block copolymer composition in grapho-epitaxy directed self-assembly for contact hole multiplication

status: publishe

Controlling placement error and dimensional variability in templated DSA

Directed self-assembly (DSA) of block-copolymers (BCP) is considered as a complementary patterning technique to Extreme ultra violet (EUV) lithography at dimensions below 20nm half-pitch. Critical challenges on DSA hole shrink and multiplication include critical dimension uniformity (CDU) and placement errors. In this study we will demonstrate the impact of the conventional lithography step and variations in the template shape on the pattern placement and CDU of the DSA holes. We will focus on the formation of singlets (i.e. contact hole shrink), and doublets. Conventional lithography techniques (ArF or EUV) are used to create a pre-pattern that guides the phase separation process. After surface modification, a polystyrene-b-methyl methacrylate (PS-b-PMMA) is deposited in the templates and annealed at elevated temperature. Annealing results in a phase separation of the polymer into cylindrical patterns (Figure 1). After removing the minority block (in this case PMMA), this pattern is transferred in an underlying SiN layer for pattern placement and CDU characterization. The higher resolution of EUV enables template shape control. This is expected to give a pattern placement improvement. In addition, the templates can be pre-shaped to more commensurate shapes than ellipses (e.g. in peanuts), which is expected to further reduce placement errors.status: submitte