Analysing trimethylaluminum infiltration into polymer brushes using a scalable area selective vapor phase process

Snelgrove, Matthew; McFeely, Caitlin; Shiel, Kyle; Hughes, Greg; Yadav, Pravind; Woicik, J. C.; Mani-González, P.G.; Lundy, Ross; Morris, Michael A.; McGlynn, Enda; O’Connor, Robert

doi:10.1039/d0ma00928h

Cited by 15 publications

(9 citation statements)

References 71 publications

(70 reference statements)

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“… 26 Each repeating unit in MH has two ether oxygen atoms, or 13 per molecule, while there is only one carbonyl group per molecule. Another possibility is the interaction between TMA and the nitrogen atoms, which occurs, e.g., for infiltration in poly(vinyl pyridine), 53 since there are four nitrogen atoms per molecule. These functional groups are all located on the MH side of the molecule.…”

Section: Resultsmentioning

confidence: 99%

Poly(styrene)-block-Maltoheptaose Films for Sub-10 nm Pattern Transfer: Implications for Transistor Fabrication

Löfstrand

Jam

Mothander

et al. 2021

ACS Appl. Nano Mater.

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Sequential infiltration synthesis (SIS) into poly(styrene)- block -maltoheptaose (PS- b -MH) block copolymer using vapors of trimethyl aluminum and water was used to prepare nanostructured surface layers. Prior to the infiltration, the PS- b -MH had been self-assembled into 12 nm pattern periodicity. Scanning electron microscopy indicated that horizontal alumina-like cylinders of 4.9 nm diameter were formed after eight infiltration cycles, while vertical cylinders were 1.3 nm larger. Using homopolymer hydroxyl-terminated poly(styrene) (PS–OH) and MH films, specular neutron reflectometry revealed a preferential reaction of precursors in the MH compared to PS–OH. The infiltration depth into the maltoheptaose homopolymer film was found to be 2.0 nm after the first couple of cycles. It reached 2.5 nm after eight infiltration cycles, and the alumina incorporation within this infiltrated layer corresponded to 23 vol % Al 2 O 3 . The alumina-like material, resulting from PS- b -MH infiltration, was used as an etch mask to transfer the sub-10 nm pattern into the underlying silicon substrate, to an aspect ratio of approximately 2:1. These results demonstrate the potential of exploiting SIS into carbohydrate-based polymers for nanofabrication and high pattern density applications, such as transistor devices.

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Section: Resultsmentioning

confidence: 99%

Poly(styrene)-block-Maltoheptaose Films for Sub-10 nm Pattern Transfer: Implications for Transistor Fabrication

Löfstrand

Jam

Mothander

et al. 2021

ACS Appl. Nano Mater.

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“…This process has previously been studied for a number of materials, such as of the precursor trimethyl aluminum (TMA) into poly(metyl methacrylate) (PMMA) [8], poly(2-vinylpyridine) (P2VP) [9], hydroxyl-terminated poly(styrene) (PS-OH) [10], and maltoheptaose (MH) [10]. Functional groups that have been identified to react with TMA precursor are, e.g., hydroxyl groups (-OH) [11], carbonyl groups (>C=O) [8], and pyridines [12]. Some of the characterization techniques for SIS are Fourier transform infrared spectroscopy (FTIR) [13], quartz crystal microbalance (QCM) [14], scanning transmission electron microscopy (STEM) tomography [15], ellipsometry [16], grazing incidence small angle X-ray scattering (GISAXS) [8], and grazing incidence small angle neutron scattering (GISANS) [17].…”

Section: Introductionmentioning

confidence: 99%

Sequential Infiltration Synthesis into Maltoheptaose and Poly(styrene): Implications for Sub-10 nm Pattern Transfer

et al. 2022

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Vapor phase infiltration into a self-assembled block copolymer (BCP) to create a hybrid material in one of the constituent blocks can enhance the etch selectivity for pattern transfer. Multiple pulse infiltration into carbohydrate-based high-χ BCP has previously been shown to enable sub-10 nm feature pattern transfer. By optimizing the amount of infiltrated material, the etch selectivity should be further improved. Here, an investigation of semi-static sequential infiltration synthesis of trimethyl aluminum (TMA) and water into maltoheptaose (MH) films, and into hydroxyl-terminated poly(styrene) (PS-OH) films, was performed, by varying the process parameters temperature, precursor pulse duration, and precursor exposure length. It was found that, by decreasing the exposure time from 100 to 20 s, the volumetric percentage on included pure Al2O3 in MH could be increased from 2 to 40 vol% at the expense of a decreased infiltration depth. Furthermore, the degree of infiltration was minimally affected by temperature between 64 and 100 °C. Shorter precursor pulse durations of 10 ms TMA and 5 ms water, as well as longer precursor pulses of 75 ms TMA and 45 ms water, were both shown to promote a higher degree, 40 vol%, of infiltrated alumina in MH. As proof of concept, 12 nm pitch pattern transfer into silicon was demonstrated using the method and can be concluded to be one of few studies showing pattern transfer at such small pitch. These results are expected to be of use for further understanding of the mechanisms involved in sequential infiltration synthesis of TMA/water into MH, and for further optimization of carbohydrate-based etch masks for sub 10 nm pattern transfer. Enabling techniques for high aspect ratio pattern transfer at the single nanometer scale could be of high interest, e.g., in the high-end transistor industry.

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“…ASD has been defined as a process by which film formation is allowed on certain areas of a substrate while not depositing on adjacent regions. 14 This is achieved through the chemical activation 9,15,16 or deactivation [17][18][19] of particular substrate regions. ASD has been shown to have the capacity to fabricate high-resolution patterned substrates, which have the potential to overcome the technical and financial limitations that photolithography currently faces.…”

Section: Introductionmentioning

confidence: 99%

“…29,31,32 Similar to SAMs, certain polymer brushes can be used to selectively deactivate particular regions on a substrate, but as well as this, they can selectively activate based on the polymer's chemistry. 15,33,34 A polymer brush can be defined as an end grafted polymer chain bound to a surface whereby the chains stretch away from the substrate. 35,36 These polymer chains are typically covalently bonded to the surface of the substrate.…”

Section: Introductionmentioning

confidence: 99%

Rapid area deactivation for blocking atomic layer deposition processes using polystyrene brush layers

et al. 2022

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Analysing trimethylaluminum infiltration into polymer brushes using a scalable area selective vapor phase process

Abstract: This work identifies the critical factors when developing a polymer brush vapor phase infiltration process, while also demonstrating the use of novel pyridines for area selective purposes.

Cited by 15 publications

References 71 publications

Poly(styrene)-block-Maltoheptaose Films for Sub-10 nm Pattern Transfer: Implications for Transistor Fabrication

Poly(styrene)-block-Maltoheptaose Films for Sub-10 nm Pattern Transfer: Implications for Transistor Fabrication

Sequential Infiltration Synthesis into Maltoheptaose and Poly(styrene): Implications for Sub-10 nm Pattern Transfer

Rapid area deactivation for blocking atomic layer deposition processes using polystyrene brush layers

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