| 1. |
- Löfstrand, Anette, et al.
(författare)
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Poly(styrene)- block-Maltoheptaose Films for Sub-10 nm Pattern Transfer : Implications for Transistor Fabrication
- 2021
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 4:5, s. 5141-5151
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Tidskriftsartikel (refereegranskat)abstract
- 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 % Al2O3. 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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| 2. |
- Löfstrand, Anette, et al.
(författare)
-
Sequential infiltration synthesis and pattern transfer using 6 nm half-pitch carbohydrate-based fingerprint block copolymer
- 2021
-
Ingår i: Advances in Patterning Materials and Processes XXXVIII. - : SPIE. - 1996-756X .- 0277-786X. - 9781510640573 - 9781510640580 ; 11612
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Konferensbidrag (refereegranskat)abstract
- This study presents how sequential infiltration synthesis of trimethyl aluminium and water into a carbohydrate-based block copolymer was used to enable pattern transfer of 6 nm half-pitch horizontal cylinders into silicon. Specular neutron reflectometry measurements of poly(styrene)-block-maltoheptaose self-assembled into horizontal cylinders indicate an increasing content of alumina after each sequential infiltration cycle, comparing 0, 1, 2, and 4 cycles, with alumina content reaching 2.4 vol% after four infiltrations cycles. Dry etching processes in inductively coupled plasma reactive ion etching for sub-10 nm patterns were developed, using a two-step technique: O2-plasma for polymer removal and a reactive ion etching of Si using a mixture of SF6 and C4F8 gases. Etch selectivity of more than 2:1 of silicon over alumina-like etch mask material was achieved. To evaluate the etching process, the etched Si structures were measured and characterized by scanning electron microscopy. These results are expected to be of use for nanofabrication and applications in the sub-10 nm regime.
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| 3. |
- Löfstrand, Anette, et al.
(författare)
-
Sequential Infiltration Synthesis into Maltoheptaose and Poly(styrene): Implications for Sub-10 nm Pattern Transfer
- 2022
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Ingår i: Polymers. - : MDPI AG. - 2073-4360. ; 14:4, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- 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. Mul- tiple 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 selectiv- ity 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, precur- sor 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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