SU456197A2 - Waveguide cell for measuring the electromagnetic characteristics of a substance - Google Patents

Description

one

The invention relates to a test technique and can be used for contactless, non-destructive testing of semiconductor or dielectric films on low-resistance semiconductor and conductive substrates.

A waveguide cell is known for measuring the electromagnetic characteristics of a substance according to the author. St. No. 240775 is formed by a waveguide section with a short-circuiting piston, inside which a quarter-wave dielectric insert is placed to increase the measurement accuracy at a distance equal to an even number of half-waves. In this case, the test sample must be introduced into the space between the liner and the short-circuiting piston.

The purpose of the invention is to change the thickness of semiconductor and dielectric films on heavily doped substrates.

For this waveguide cell, the liner radius is made equal to the radius of the cell cavity, which meets the condition of 0.49A, .0.5Ko, and Yao is the critical wavelength; d is the radius of the cell, and is made of a material with small dielectric losses, and its end is intended to contact with the film and the substrate.

The drawing schematically depicts the described cell.

To measure the thickness of films on heavily doped substrates, the waveguide cell 1 with a quarter-wave dielectric pad 2 with high accuracy forms a resonant volume excited from the side by waveguides 3.

The liner with small dielectric losses and a radius equal to the radius of the cell is located at a distance multiple to an odd number of quarters of wavelengths from the shorting piston 4, and one end of it

intended for contacting the sample. The sample is alternately in contact with the dielectric face: M cells with the side of the substrate 5 and the film 6. To increase the sensitivity, the cell radius is chosen from the condition 0, 5Ао, where r is the radius of the cell;

Yao is the critical wavelength of a cell.

When replacing the end wall of a cell with a sample from the side of the film, the position of the liner is changed by the thickness of the film compared to its position when replacing the end wall with a sample from the side of the substrate. This changeable when operating at a constant frequency leads to the need for an increased in (pr / pO)

By shifting the position of the piston in the empty part of the cell, it is tuned to resonance. Here, | 32 is the constant distribution in the dielectric insert; | 3i - constant distribution in the unfilled part of the cell.

The determination of the thickness and film is made by the formula h (pi / p2) A, where D is the film-induced shift in the resonant position of the piston in the empty part of the cell compared to its position when the measuring end is replaced with a sample from the substrate side. The operating frequency should be chosen such that 1 percent of the substrate is significantly greater than the depth of the skin layer.

Subject invention

Waveguide cell for measuring the electromagnetic characteristics of a substance according to ed. St. N ° 240775, characterized in that, in order to measure also the thickness of epitaxial nalunoduction and dielectric films on doped substrates, the liner radius is equal to the cell cavity radius, which meets the condition 0, 5А, o, where K o is the critical cell wavelength; d is the radius of the cell, and is made of a material with small dielectric losses, and its end is intended for contact with the film and substrate.