Arjun Singh

Rectification of EUV-patterned contact holes using directed self-assembly

One critical problem with EUV patterning is the local CD variation of contact holes. The issue is especially problematic for patterning of sub-30nm hole dimensions. Although the EUV wavelength enables resolution of fine contact patterns, shot noise effects (both chemical and optical) result in high levels of CD non-uniformity. Directed self-assembly (DSA) offers the possibility of rectifying this non-uniformity. Since the resulting CD in this patterning approach is typically dictated by the polymer size, application of this technology in conjunction with an EUV-defined pre-pattern can theoretically improve the local CD uniformity. Integration approaches using both chemo- and grapho-epitaxy integration may be used to achieve DSA enabled uniformity improvement. The drawbacks and benefits of both approaches will be discussed. Finally, these types of DSA flows also enable frequency multiplication to achieve dense arrays from an initially sparse pattern. In this study, we will report on a variety of schemes to attain rectification and frequency multiplication.

Using chemo-epitaxial directed self-assembly for repair and frequency multiplication of EUVL contact-hole patterns

The patterning potential of block copolymer materials via various directed self-assembly (DSA) schemes has been demonstrated for over a decade. At cost-effective low printing doses, extreme ultra-violet lithography (EUVL) suffers from shot noise effects while patterning sub 30 nm contact hole dimensions. As the critical dimension (CD) of DSA systems is largely determined by polymer dimensions, it is theoretically expected that the local CD uniformity (LCDU) of EUVL pre-patterns can be improved by the DSA of pitch matched block co-polymers. In this work we demonstrate continued improvements on our previously reported chemo-epitaxy DSA integration flow. Also, we achieve dense arrays of contact holes via 3x and 4x frequency multiplication of EUVL patterned contact hole arrays.

Patterning sub-25nm half-pitch hexagonal arrays of contact holes with chemo-epitaxial DSA guided by ArFi pre-patterns

The patterning potential of block copolymer (BCP) materials via various directed self-assembly (DSA) schemes has been demonstrated for over a decade. We have previously reported the HONEYCOMB flow; a process flow where we utilize Extreme Ultraviolet Lithography and Oxygen plasma to guide the assembly of cylindrical phase BCPs into regular hexagonal arrays of contact holes [1, 2]. In this work we report the development of a new process flow, the CHIPS flow, where we use ArFi lithography to print guiding patterns for the chemo-epitaxial DSA of BCPs. Using this process flow we demonstrate BCP assembly into hexagonal arrays with sub-25 nm half-pitch and discuss critical steps of the process flow. Additionally, we discuss the influence of under-layer surface energy on the DSA process window and report contact hole metrology results.

Manufacturability of dense hole arrays with directed self-assembly using the CHIPS flow

Directed self-assembly (DSA) of block copolymers (BCP) has attracted significant interest as a patterning technique over the past few years. We have previously reported the development of a new process flow, the CHIPS flow (Chemo-epitaxy Induced by Pillar Structures), where we use ArFi lithography and plasma etch to print guiding pillar patterns for the DSA of cylindrical phase BCPs into dense hexagonal hole arrays of 22.5 nm half-pitch and 15 nm half-pitch [1]. The ability of this DSA process to generate dense regular patterns makes it an excellent candidate for patterning memory devices. Thus, in this paper we study the applicability of the CHIPS flow to patterning for DRAM storage layers. We report the impact of various process conditions on defect density, defect types and pattern variability. We also perform detailed analysis of the DSA patterns, quantify pattern placement accuracy and demonstrate a route towards excellent LCDU after pattern transfer into a hard mask layer.

Development and evaluation of a-SiC:H films using a dimethylsilacyclopentane precursor as a low-k Cu capping layer

Scaling of the Cu interconnect structures requires Cu capping layers with an increasingly lower dielectric constant (K) that still have adequate Cu and moisture barrier properties. In this work, we study the plasma enhanced chemical vapour (PE-CVD) deposition of amorphous silicon carbide films using dimethyl silacyclopentane (DMSCP) as a precursor, resulting in the incorporation of Si-(CH2)n-Si bridges. The effect of process parameters on film characteristics like K, mass density (p), and leakage behaviour is investigated, as well as their relation with the chemical bonding structure. Finally, Cu barrier properties and hermeticity are evaluated.