Besides these theoretical considerations, attempts to use this inhibited CVD to deposit B-C films in narrow, deep trenches were made using both digital random-access memory (DRAM) structures and on a PillarHall® test chip. The DRAM structures consisted in 110-nm-wide holes with aspect ratio of 60:1. As shown in Figure the holes were coated with a BxC film down to the bottom of the feature, without pinch-off of the openings. The film was deposited for 60 minutes and its thickness varies from 30 to around 15 nm from top to bottom showing that the deposition is not perfectly conformal under these conditions. Attempts to evaluate the limits of the deposition process in terms of maximal aspect ratio were done using a LHAR (lateral high aspect ratio) test chip from PillarHall®. It consists of horizontal trenches with different aspect ratio ranging from 2:1 to 10048:1. With 120 min deposition at the same conditions as for the DRAM structures, it was possible to deposit a film in a lateral trench of aspect ratio as high as 2000:1, the film was 47 nm at the opening and 28 nm at the bottom, as shown on Figure ). It was also possible to deposit a film into a lateral trench with aspect ratio 10048:1 (Figure ) where the film was 50 nm thick at the inlet and too thin to accurately measure by SEM at the bottom. After removal of the PillarHall® membrane, XPS measurements (Figure ) in the middle of the 10048:1 trench without sputtering show a B/C ratio of 0.45. Measurement outside the trenches show a similar B/C ratio of 0.50 prior to sputtering and a B/C ratio of 0.69 after sputtering of the adventitious carbon, which is consistent with the values reported in reference 8 .