In this work, we investigated the self-assembly of a lamellar block copolymer (BCP) under different wetting conditions. We explored the influence of the chemical composition of under-layers and top-coats on the thin film stability, self-assembly kinetics and BCP domain orientation. Three different chemistries were chosen for these surface affinity modifiers and their composition was tuned in order to provide either neutral wetting (i.e. an out-of-plane lamellar structure), or affine wetting conditions (i.e. an in-plane lamellar structure) with respect to a sub-10 nm PS- b -PDMSB lamellar system. Using such controlled wetting configurations, the competition between the dewetting of the BCP layer and the self-organization kinetics was explored. We also evaluated the spreading parameter of the BCP films with respect to the configurations of surface-energy modifiers and demonstrated that BCP layers are intrinsically unstable to dewetting in a neutral configuration. Finally, the dewetting mechanisms were evaluated with respect to the different wetting configurations and we clearly observed that the rigidity of the top-coat is a key factor to delay BCP film instability.

Different self-segregation behavior of ABA triblock copolymers with central PBD or PBD H blocks and semi-crystalline or amorphous PCL-like external blocks.

Results for the self-assembly of lamellar silicon-containing high-χ block copolymers (BCP) with innovative neutral top-coat design are presented. We demonstrate that these materials and associated processes are compatible with a standard lithographic process, and oriented toward a potential high volume manufacturing. We show that this dedicated technology is able to guarantee the stability and planarity of the stack even at elevated self-assembly bake temperatures, and opens new opportunity in the fields of 3D BCPs stacks. Finally, we show interesting results for the etch-transfer of a lamellar BCP in silicon.

The directed self-assembly (DSA) of block copolymers (BCPs) is a powerful method for the manufacture of high-resolution features. Critical issues remain to be addressed for successful implementation of DSA, such as dewetting and controlled orientation of BCP domains through physicochemical manipulations at the BCP interfaces, and the spatial positioning and registration of the BCP features. Here, we introduce novel top-coat (TC) materials designed to undergo cross-linking reactions triggered by thermal or photoactivation processes. The cross-linked TC layer with adjusted composition induces a mechanical confinement of the BCP layer, suppressing its dewetting while promoting perpendicular orientation of BCP domains. The selection of areas of interest with perpendicular features is performed directly on the patternable TC layer via a lithography step and leverages attractive integration pathways for the generation of locally controlled BCP patterns and nanostructured BCP multilayers.

Directed self-assembly (DSA) of block copolymers (BCPs) is an advanced patterning technique being investigated to obtain small and dense patterns for future technological nodes. In order to demonstrate the potential of DSA to extend optical lithography, poly(styrene-b-methyl methacrylate) (PS-b-PMMA) has been the most commonly used block copolymer in different applications, such as line/space and contact hole patterning as well as uniformity repair. However, the minimum pitch for the PS-b-PMMA system is limited to around 24 nm due to its relatively weak segregation strength. Therefore, block copolymers with stronger microphase segregation have been developed to enable sub-10 nm patterning, thus obtaining the so-called “high chi” BCPs. In this article, the silicon-containing high chi system investigated is the poly(styrene-b-1,1-dimethylsilacyclobutane) (PS-b-PDMSB) presenting a pitch of 18 nm. A one-step top coat and PS removal based on H2/N2 plasma that presents good selectivity and profile has been studied. The H2/N2 gas ratio has been investigated to understand the trade-off between obtaining high selectivity and avoiding pattern collapse. Using this approach, the pattern transfer into different underlayers is demonstrated for the high chi PS-b-PDMSB.

A concept of patternable top-coats dedicated to directed self-assembly of high- χ block copolymers is detailed, where the design enables a crosslinking reaction triggered by thermal or photo-activation. Nanostructured BCP areas with controlled domains orientation are selected through a straightforward top-coat lithography step with unique integration pathways. Additionally, the crosslinked nature of the material enables the suppression of the BCP dewetting, while exhibiting exceptional capabilities for the construction of 3D stacks.

Directed Self-Assembly of block copolymers is a lithographic technique being developed to reach sub-10 nm technological nodes. Recently, high chi block copolymers have been developed to achieve higher resolution. In this paper, the high chi system investigated is a modified polystyrene-b-poly(methyl methacrylate)(PS-b-PMMA) presenting a pitch of 18 nm. One critical step for its integration is the PMMA removal selectively to the PS. Two approaches to remove the PMMA phase are presented, highlighting the challenges encountered due to its smaller dimensions. The first one is a full dry approach based on a CH4/N-2 chemistry, which presents some bridge formation due to intensive sidewalls passivation and to a species confinement effect accentuated by the small 9nm critical dimension of the lines. Therefore, the main high chi PS-b-PMMA dry etching difficulties come from the trade-off between obtaining high selectivity and avoiding bridge formation. The second approach is a mixed wet and dry PMMA removal process based on UV exposure followed by solvent rinse. An Ar/O-2 dry brush layer opening was developed and the pattern transfer into the SiO2 and Si underlayers is demonstrated for the high chi PS-b-PMMA.

Directed Self-Assembly (DSA) of Block Copolymers (BCP) by chemo-epitaxial alignment is a promising high resolution lithography technique compatible with CMOS high-volume manufacturing. It allows overcoming limitations in resolution and local stochasticity by conventional, imaging based, lithography. However, for BCP with pitches below 20 nm and guide patterning by immersion lithography (193i), multiplication factors ≥ 4 become necessary, imposing stringent requirements on the guides and defectivity becomes hard to control. The Arkema-CEA (ACE) process flow overcomes this limit by creating the guides by a self-aligned double patterning (SADP) process flow, followed by the deposition of a cross-linkable neutral mat and selective grafting of the guides. This paper reports on the transfer of the process flow to immersion lithography, details challenges encountered in process optimization, notably the dependence of the wetting of the neutral layer on the surface energy and the morphology of the spacers. Last, the paper presents a metrology and defectivity roadmap combined with preliminary, promising results.

This paper introduces line roughness characterization non-straight patterns made of block copolymers (fingerprint patterns). Line Width Roughness have been determined using Power Spectral Density based on a special edge detection developed at CEA-LETI to extract edges contours. We investigated several process parameters impact on LWR such as the degree of polymerization of different BCPs and the impact of UV irradiation on the roughness of the PS block.

In this work, an evaluation of various adhesion promoters (or primers) for soft ultra-violet (UV) nanoimprint lithography (NIL) is reported. The evaluation is performed using 200 mm wafer scale in the HERCULES® NIL equipment platform available at the CEA-Leti. First, surface energies of the primers are determined through contact angle measurements. Next, atomic force microscope (AFM) measurements were carried out to evaluate the surface uniformity and roughness of the primed wafers. Thin film thickness measurements were performed by spectroscopic ellipsometry in order to select the most promising primer processes for high resolution etch mask and permanent applications. Afterwards, the adhesion layer performances of the selected primer processes were evaluated by an imprint test using a dedicated patterned master (critical dimension down to 30 nm and aspect ratios up to 1.5). Optical and scanning electron microscope (SEM) defect reviews were systematically performed. This evaluation enabled to benchmark several adhesion promotor solutions based on the grafted technology developed by ARKEMA in order to identify an efficient adhesive layer compatible with various NIL resists and substrates, such as silicon based materials or glass.

Directed Self-Assembly (DSA) of Block Copolymer (BCP) is a promising lithography approach to achieve high resolution pattern dimensions. The current chemo-epitaxy process used to induce block copolymer self-alignment is showing today its limitations. This is due to the resolution limitation of conventional lithography technics needed for the guide formation, used to achieve BCP alignment. This paper introduces a new chemo-epitaxy process, named ACE (Arkema-CEA), which is based on sidewall image transfer (SIT) patterning. This process has the great advantage to offer guides of small critical dimension (CD) and pitch that allows the integration of high chi BCP. In this paper, different parameters of the ACE process are investigated (commensurability, spacer CD ... ) in order to precisely determine the DSA process window defining the best conditions for BCP alignment. Process window with multiplication factor ranging from 2 to 4 are obtained on BCP under investigation.

Directed Self-Assembly (DSA) of block-copolymers, which is an affordable, simple and versatile lithography technique, is still highly investigated as a potential solution for the next generation node in the CMOS industry. DSA graphoepitaxy approach provides physical confinement between two “sidewalls” of fixed surface energy, which will generate well defined line/space structures with a variety of block copolymer materials and process environment [1,2,3]. However, most pilot-line compatible processes found in literature use Electron Beam Lithography (EBL) to generate the guiding structures because non-preferential grafted polymer layers can be incorporated between the HSQ resist (oxide guiding templates) and an inorganic transfer layer [4]. When using a 193nm-immersion lithography, such integration flow is not advised because the 193nm resists are acrylate-based resists that flow during the different annealing steps (CD uniformity and roughness performances impacted). Guiding templates made of standard immersion “hardmask” stack material with proper surface functionalization (sidewalls attractive to one block, bottom non-preferential) are rare.

CH (Contact hole) patterning by DSA (Directed Self-Assembly) of BCP (Block Copolymer) is still attracting interest from the semiconductor industry for its CH repair and pitch multiplication advantages in sub-7nm nodes. For several years, extensive studies on DSA CH patterning have been carried out and significant achievements have been reported in materials and process optimization, CMOS integration and design compatibility and advanced characterization [1-4]. According to these studies, if a common agreement was clearly made for the use of PS-b-PMMA material as a potential candidate for DSA CH patterning integration in advanced nodes, the associated guiding template material was not yet selected and is still under investigation. Whereas the most reported guiding template materials for DSA PS-b-PMMA CH patterning are organic-based (resist or organic hard mask), we propose in this work to investigate a DSA process based on inorganic template material (silicon oxide based). Indeed, this latter offers some advantages over organic template: better surface affinity control, higher thermal stability during BCP self-assembly annealing, easier 3D-morphology imaging of DSA patterns and the possibility of wafer rework after the DSA step. The inorganic template based DSA process was first optimized using the planarization approach [5]. We demonstrated that the silicon oxide thickness should be properly adjusted to allow a good control of the BCP thickness over different guiding template densities. Afterwards, we compared the DSA performances (critical dimension: CD; CD uniformity: CDU, contact misalignment and defectivity) between both inorganic and organic template approaches. Equivalent results were obtained as shown in Figure 1. Finally, we demonstrated that inorganic template allows the rework of DSA wafers: similar CD and CDU for both guiding and DSA patterns were obtained after 3 cycles of rework (Figure 2).

Polybutyrolactone tri- and diblock copolymers with well-defined structures and narrow molar distributions were prepared by trifluoromethanesulfonic acid-organocatalyzed ring-opening polymerization of β-butyrolactone initiated with dihydroxylated poly(hydrogenated butadiene) and hydroxylated polystyrene. Study of the phase separation behavior of these block copolymers in the bulk and in thin film shows their ability to segregate even for low molecular weights, giving rise to spherical, cylindrical, and lamellar morphologies with periodicities in the range 10–20 nm. The Flory–Huggins interaction parameters estimated from the order-to-disorder transition temperatures are in the same range or higher than those of other block copolymers associating biodegradable and polyolefin blocks.

In this work, an evaluation of various ASL processes for 200 mm wafer scale in the HERCULES® NIL equipment platform available at the CEA-Leti through the INSPIRE program is reported. The surface and adherence energies were correlated to the AFM and defectivity results in order to select the most promising ASL process for high resolution etch mask applications. The ASL performances of the selected process were evaluated by multiple working stamp fabrication using unpatterned and patterned masters though defectivity monitoring on optical based-inspection tools. Optical and SEM defect reviews were systematically performed. Multiple working stamps fabrication without degradation of the master defectivity was witnessed. This evaluation enabled to benchmark several ASL solutions based on the grafted technology develop by ARKEMA in order to reduce and optimize the soft stamp defectivity prior to its replication and therefore considerably reduce the final imprint defectivity for the Smart NIL process.