V. P. Gavrilenko

Measurements of linear dimensions of silicon nanorelief elements with a near-rectangular profile by defocusing the electron probe of a scanning electron microscope

Solitary silicon nanorelief elements with different widths are studied with the use of a scanning electron microscope (SEM). From the video signal curves obtained in the secondary-slow-electron mode of SEM measurements, the dependences of the length of check segments Gp(Def) and Lp(Def), where Def is the effective diameters of the SEM probe, are determined. The dependences are found to be linear for all four solitary protrusions, and as Def is increased, the length Gp increases and the length Lp decreases. It is shown that the method of defocusing the SEM electron probe provides a means for determining the linear dimension of nanorelief elements with a near-rectangular profile by extrapolating the linear dependences Gp(Def) and Lp(Def) to Def = 0. It is established that the invariant check segment representative of the linear dimension of a particular relief element is at the level (sl)aver = 0.80 ± 0.03 for silicon elements with different widths.

Measurement of the native oxide thickness on a reference relief pitch structure on a single-crystal silicon substrate

A reference relief pitch structure formed on a single-crystal silicon surface is investigated. The structure consists of trapezoidal elements (protrusions) with a pitch of 2 μm. The protrusions with upper bases of about 100 and 10 nm are located in one chip. The lateral surface of the element is tilted relative to its base by an angle of 54.7°. The entire structure is coated with the native oxide formed at room temperature. The oxide thickness is measured on an atomic-resolution transmission electron microscope in the mode of direct resolution of the crystal structure. In the measurements, the known distance between the {111} planes was used. It is established that the native oxide thickness depends on the sizes of both the protrusion’s upper base and bottom profile between the neighboring protrusions. It is demonstrated experimentally that in the region of the bottom, the native oxide thickness increases from 2.4 nm in the center of the bottom to 5 nm at the left and right bottom edges.

Natural oxide thickness measurements on the test silicon relief pitch structure

The study was performed on a test step relief structure of monocrystalline silicon. There was experimentally measured the thickness of the natural oxide on this structure consisting of a set of elements (protrusions) with a trapezoidal profile and 2.0 μm step size, upper base about 10 nm, height about 500 nm. The tilt angle of side face with respect to the lower base was 54.7°. The entire structure was covered with a natural oxide film that appeared at room temperature, the thickness of which is being measured using a transmission electron microscope with atomic resolution by the observed pattern in the direct mode resolution of the crystal structure. In order to calibrate the measurements a distance between {111} planes was used. It was shown experimentally, that in the area of this bottom the natural oxide thickness increases from 2.3 ± 0.2 nm in the middle of the bottom to 3.0 ± 0.2 nm and 4.5 ± 0.2 nm at the left and right edges of the bottom, respectively.

Scanning electron microscopy used to measure the feature dimensions of a nanoscale test pattern on a silicon surface

A method is proposed for nanoscale dimensional metrology with the scanning electron microscope in the case of an array of trapezoidal ridges on a silicon surface, the minimum feature size being comparable with the effective beam diameter. The method is tested by measuring the top width of an individual ridge, which lies between 14 and 24 nm. The method works at accelerating voltages higher than 15 kV.