MODIFICATION OF DIAMOND SURFACE DURING PHOTOLITHOGRAPHY, PLASMA-CHEMICAL CLEANING, AND MAGNETRON DEPOSITION

Abstract

An influence of the conventional planar technology of the semiconductor surface treatment operations (photolithography, plasma-chemical surface cleaning in radio frequency low-pressure oxygen discharge, and thin metal films growth) on monocrystalline diamond surface topography and roughness is investigated. It is preliminary shown that photolithography without the plasma cleaning and magnetron deposition of an aluminum film do not induce any diamond surface changes which could be found by the optical profilometry, electron and optical microscopy. However, as a result of the lithography some organic contaminants can decrease the adhesion of the aluminum film and have to remove from the surface. Further, the influence of the above-listed surface treatment operations separately and in combinations on the synthetic diamond surface is investigated. It is found that an even short oxygen plasma cleaning during 5 min with a low bias power of 20 W leads to etching the grooves on the diamond surface The depth of the etching grooves varies by more than an order of magnitude in different experiments (0.3 - 19 nm), and by 10-20% within the same substrate under the influence of the poorly controlled external factors. Also, oxygen plasma treatment changes its secondary electron emission coefficient. Deposition of aluminum film after plasma cleaning does not induce noticeable changes in the diamond surface topography. The quality of diamond surface polishing (in “hard” of “soft” direction), the diamond’s type (IIa or IIb) as well as producing method (HPHT or homoepitaxial CVD) do not affect the result of grooves formation.