期刊
ACS APPLIED MATERIALS & INTERFACES
卷 13, 期 27, 页码 32381-32392出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.1c04405
关键词
area-selective ALD; atomic-layer deposition; amorphous carbon; halogenation; plasma treatment
资金
- European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program [716472, 875577]
- Research Foundation Flanders (FWO Vlaanderen) [G85720N, 1501618N, G0E6319N, G0H0716N]
- KU Leuven [C32/18/056]
- European Research Council (ERC) [875577] Funding Source: European Research Council (ERC)
This study demonstrates the selective deposition of TiO2 by plasma halogenation of amorphous carbon, addressing the alignment issue in integrated circuits. By utilizing cyclic fluorination, defect-free deposition of TiO2 is achieved, with better growth inhibition compared to chlorination.
As critical dimensions in integrated circuits continue to shrink, the lithography-based alignment of adjacent patterned layers becomes more challenging. Area-selective atomic layer deposition (ALD) allows circumventing the alignment issue by exploiting the chemical contrast of the exposed surfaces. In this work, we investigate the selective deposition of TiO2 by plasma halogenation of amorphous carbon (a-C:H) acting as a growth-inhibiting layer. On a-C:H, a CF4 or Cl-2 plasma forms a thin halogenated layer that suppresses the growth of TiO2, while nucleation remains unaffected on plasma-treated SiO2. The same halogenating plasmas preferentially etch TiO2 nuclei over films and thus enable the restoration of the halogenated surface of amorphous carbon. By embedding the intermediate plasma treatments in the ALD TiO2 sequence, an 8 nm TiO2 layer could be deposited with a selectivity of 0.998. The application of the cyclic process on a 60 nm half-pitch line pattern resulted in the defect-free deposition of TiO2 at the bottom of the trenches. Cyclic fluorination demonstrated better growth inhibition compared to chlorination due to more efficient defect removal and retention of the favorable surface composition during plasma exposure. While exploring the TiO2 nucleation defects at the limit of detection for conventional elemental analysis techniques (<1 x 10(14) at/cm(2)), we additionally highlight the value of imaging techniques such as atomic force microscopy for understanding defect formation mechanisms and accurately assessing growth selectivity.
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