Friday, February 26, 2021

Area-selective MLD of nylon 6: Growth on carbon and inhibition on silica for a-carbon hardmask repair

Here one of the Editor pic out of the JVSTA Special Topic Collection on Area Selective Deposition. Marcel Junige, is one of Dresden´s top-notch ALD and MLD scientists that went over there to the University of Colorado Boulder to S M Geroge´s famous lab. In this demonstration, it is illustrated the capability of area-selective MLD to repair RIE-eroded aC hard masks and to maintain the critical dimension, which is key in all leading etch semiconductor manufacturing processing schemes. It is a fairly typical situation in this business, the CMP or Etch guys brutally destroy stuff that has to be repaired by ALD or Wet processing, sometimes even by E-Beam single exposure repair. That is maybe one of the drivers behind the more precise and gentle ALE method. Yeah E-CMP ever made it.

Area-selective molecular layer deposition of nylon 6,2 polyamide: Growth on carbon and inhibition on silica

Journal of Vacuum Science & Technology A 39, 023204 (2021);
Marcel Junige and Steven M. George

In microelectronic or nanoelectronic manufacturing, pattern transfer by directional reactive ion etching (RIE) progressively erodes amorphous carbon (aC) hard masks. To maintain critical dimensions and tolerances of high-aspect-ratio device structures, new carbonaceous materials may be added repeatedly to replace the eroded aC hard mask. Such a mask repairing step during RIE needs self-aligning growth of organic materials. Area selectivity is required to deposit the organic material on the aC hard mask exclusively. Deposition on the dielectric or semiconductor device structures underlying the mask would complicate their precise etching or later cleaning. When ashing the aC hard mask, all-organic materials are preferable to organic-inorganic hybrid materials because they leave no residue. In this work, area-selective molecular layer deposition (MLD) was developed for the all-organic polyamide nylon 6,2. The monomer reactants for nylon 6,2 MLD were ethylene diamine and adipoyl chloride. Nylon 6,2 MLD was studied in the homogeneous, steady-state growth regime and during nucleation on various starting surfaces utilizing in situ spectroscopic ellipsometry. Area-selective MLD of nylon 6,2 was achieved on the “growth” carbon surface in the presence of silica by functionalizing aC via mild oxidation. In addition, a surface passivant was selectively attached to silica by using an amine-catalyzed coupling chemistry. The passivant inhibited the nylon 6,2 MLD on the “nongrowth” silica surface. A single passivation pretreatment was sufficient to restrict the MLD on the silica surface. The passivant, however, did not substantially impact the MLD nucleation and growth on the aC surface. This strategy yielded area selectivity with exceptionally high quality and over a wide range of MLD cycles. The area-selective MLD of nylon 6,2 was further applied on industrial test features with aC patterns masking trenches in silica. This demonstration illustrated the capability of area-selective MLD to repair RIE-eroded aC hard masks and to maintain the critical dimension.

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