The scientific team of the Moscow State Institute of Electronic Technology has developed a method of producing a nanoporous aluminum oxide, which allows you to create a range of contemporary materials for semiconductor devices, including photonic crystals. Currently, semiconductor microelectronic devices are set up mainly by optical lithography — a universal method of imaging element of the chip-on-chip semiconductor.
However, lithographic techniques are quite expensive, their development is constrained by a number of physical and technological limitations. So now actively developing methods based on the use of self-organization and self-formation.
One of these methods — nanoprofilirovanie (creating topography with nanoscale elements) of semiconductor by using the etching mask solid porous anodic alumina. Visually this fascinating scientific process can be represented as follows: pattern with the photosensitive resin material is transferred to the respective semiconductor layers of the structure are removed during the unmasked portions of polymer (in fact, this method is called etching). To optimize this process in the mask structure of alumina introduced metallic sublayer, in particular a thin film of titanium. Currently, however, the literature is almost no evidence to find the optimal design parameters of a two-layer hard mask and monitor the process nanoprofilirovaniya semiconductors with its use.
To solve this problem, scientists from the Moscow State Institute of Electronic Technology under the guidance of A. Belova investigated the process of creating a solid porous alumina mask for nanoprofilirovaniya silicon.
As starting researchers chose wafers, which by means of magnetron sputtering caused layered titanium film with a thickness of 10 to 50 nm and 2 mm thick aluminum. Two-step anodization (anodizing — electrochemical oxidation of aluminum to form on the surface of the metal oxide) aluminummask film formed of porous alumina. Thereafter, the resultant structure was subjected to install ion etching in an argon atmosphere. Using a consistent and gradual structure analysis revealed their status at different stages of the anodizing process, and after the bombing of neutral particles of argon.
The authors identified the optimal time for anodizing an effective hard mask porous alumina revealed the optimal thickness of the auxiliary sub-layer of titanium. Furthermore, they showed that the plasma etching through a mask of silicon oxide aluminum lateral dimensions recessed in the silicon depend on the aspect ratio of the alumina pores. Scientists in the course of these studies failed to achieve such conditions under which the silicon substrate nanoprofilirovanie passes so that the indentations therein have exactly repeated pattern hard mask alumina.
Source of information:
AN Belov, SA Gavrilov, Yuri Demidov, VI Shevjakov "Peculiarities of forming a mask of porous anodic aluminum oxide for the local plasma etching of silicon." Nanotechnologies in Russia, № № 11-12, 2011.