Filling of Nanometric Pores with Polymer by Initiated Chemical Vapor Deposition

Abstract

The integration of porous thin films using microelectronic compatible processes sometimes requires the protection of the interior of the pores during the critical integration steps. In this paper, the polymerization of neo‐pentyl methacrylate (npMA) is performed via initiated chemical vapor deposition (iCVD) on a porous organosilicate (SiOCH) and on a dense SiOCH. The characterizations by Fourier‐transform infrared spectroscopy, spectroscopic ellipsometry, and time‐of‐flight secondary ion mass spectrometry of the different stacks show that iCVD is a powerful technique to polymerize npMA in the nanometric pores and thus totally fill them with a polymer. The study of the pore filling for very short iCVD durations shows that the polymerization in the pores is complete in less than ten seconds and is uniform in depth. Then, the poly(npMA) film growth continues on top of the filled SiOCH layer. These characteristics make iCVD a straightforward and very promising alternative to other infiltration techniques in order to fill the porosity of microporous thin films.

Condensation‐Controlled Toposelective Vapor Deposition in Nano‐ and Microcavities: Theory, Methods, Applications, and Related Technologies

“…[36] Surface geometry directs both condensation and film flow, and sometimes it is difficult to distinguish which one is the dominant mechanism: for example, when single particles were evenly coated in the same circumstances where particle agglomerates were coated selectively in the cavities [15] or when reagents and the substrates were mixed together before equilibration. [69] Relatively complex pores have been perfectly filled, as seen in cross-sectional images of a CC-based VD process between nanopillar bundles [31] and 100 nm thick nanoporous substrate after only 3 min of exposure, [32] as long as the initiation was triggering fixation deep in the cavities. [30] It is essential to realize that cavities do not need to be concave pores but also spaces between convex surfaces are sufficient for CC and can be treated as cavities, even if the surfaces are not touching each other as shown experimentally [31,70] and mathematically.…”

“…[68] Therefore the selective deposition process, including the delayed fixation period, can be kept short. [32] A slightly delayed yet rapid initiation is probably required for high toposelectivities. If the mass transfer is efficient and initiation power is low, the process becomes effectively traditional CVD during initiation, and the film growth gains conformal or slightly subconformal characteristics.…”

“…If the mass transfer is efficient and initiation power is low, the process becomes effectively traditional CVD during initiation, and the film growth gains conformal or slightly subconformal characteristics. [31,32] However, the reagent may form oligomers or other nonvolatile intermediates during a slowly progressing fixation. The film could flow into pores instead of having the reagents condense directly inside them.…”

“…Furthermore, if the reaction is initiated thermally, the gas-liquid equilibrium is changed. Continuous gas flow systems [31,32,66] would be superior methods in most cases because they help to even out any thermal and concentration gradients making the equilibration quicker, more controllable, and more homogenous throughout the chamber.…”

“…[31] On the other hand, CC-based deposition was confirmed to work on a commercial initiated chemical vapor deposition (iCVD) reactor by simply adjusting the initiation parameters. [32] Until now, there has not been a review on VD methods utilizing CC. The literature on CC-based vapor deposition is sparse and scattered, and sometimes the observations, theory, and conclusions are contradictory in the same paper.…”