RU2598698C1 - METHOD OF MAKING THIN LAYERS OF OXIDES OF Ni, Nb WITH HOLE CONDUCTIVITY FOR MAKING COMPONENTS OF VERY LARGE SCALE INTEGRATED CIRCUITS - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention relates to electronic engineering and describes obtaining hole conductivity of an amorphous oxide film on the surface of a metal glass of Ni-Nb system by artificial oxidation. Method of making thin layers of oxides of Ni and Nb with hole conductivity for making components of very large scale integrated circuits provides for production of a thin amorphous film of the composition described by formula Nb_xNi_100-x (where x=40-60 wt%) by magnetron sputtering onto a copper water-cooled substrate at the rate of 50 nm/min at the magnetron power of 70 W and subsequent production of the composition in the thin film described by formula Nb_xNi_100-x (where x=40-60 wt%), hole conduction by annealing in an oxidizing atmosphere at the temperature of 200-300 °C during 30-60 minutes.

EFFECT: proposed is a method of making thin layers of oxides of Ni and Nb with hole conductivity.

1 cl, 4 dwg

Description

The invention relates to the field of electronic technology and describes the possibility of obtaining hole conductivity of an amorphous oxide film on the surface of a metal glass of a Ni-Nb system by artificial oxidation.

One of the promising areas of materials science is the development of functional materials based on metal glasses, including thin films with unique properties. Thus, thin films based on the Pd-Zr system obtained by magnetron sputtering have high corrosion resistance and good biocompatibility (Ketov CB, D. Luzgin), Ni-Nb films have high tribological characteristics (Caron A., Inoue,. , D. Luzgin) and magneto-optical properties in the form of partially transparent thin films.

Analysis of patent information showed that the following patents are closest to the present invention:

1. Patent US 20140015021 A1 (publ. 16.01.2014), which describes a semiconductor transistor consisting of three gates with high K-dielectric insulation and a metal gate with an operating voltage of 4.6 to 5.2 eV. The disadvantage of this invention is the low adhesive strength of semiconductor materials.

2. Patent US 4,089,710 (publ. 05.16.1978), describing the method of phosphating a metal surface by exposure to acid, to change the type of conductivity. The disadvantage of this invention is the difficulty of implementing this method due to the need to use acid.

3. Patent RU 2229755 (publ. May 27, 2004), which describes the technology of creating an ohmic contact by excluding from the manufacturing process of a thin-film device on hydrogenated amorphous semiconductors the operation of doping the film under contact with the use of toxic and explosive gases phosphine and diborane, which are replaced by the operation of annealing the film before by applying a layer of masking dielectric and metal electrodes. The disadvantage of this technology is the need to use additional technology for applying a masking dielectric.

4. Patent RU 2435251 (publ. 02.11.2006), which describes an electrode with a layer of a thin metal film and a buffer layer with high work function for use in a photovoltaic device. The disadvantage of this invention is the impossibility of a controlled change in the type of conductivity in a thin layer of a metal film.

5. Patent RU 2392688 (published on 06/20/2010), which describes a method for creating ohmic contacts in thin-film devices on amorphous undoped semiconductors, which consists in depositing a semiconductor film on a substrate, forming a masking dielectric layer, photolithography for opening windows in a dielectric layer and sputtering metal electrodes followed by photolithography for metal. The disadvantage of this invention is the need to use expensive photolithography technology for metal.

The prototype of this invention is the technology described in patent RU 2392688. The main difference between the present invention and the prototype is that when different oxidation modes are selected on the surface of an amorphous NiNb film, oxide layers with different types of conductivity are formed: when oxidized under natural conditions, an oxide film with an electronic type of conductivity, and during artificial oxidation in an oxygen atmosphere and temperatures from 250 to 350 ° C, an oxide film with a hole type of conductivity is formed.

The technical result of the invention is the possibility of obtaining hole conductivity in a thin film is achieved as follows:

1) Obtaining a thin amorphous film with the composition described by the formula Nb _x Ni _100-x (where x = 40-60 atomic%), by magnetron sputtering on a copper water-cooled substrate at a speed of 50 nm / min with a magnetron power of 70 W;

2) Annealing the film in an oxidizing atmosphere at a temperature of 200-300 ° C for 30-60 minutes.

Drawings and illustrations

FIG. 1 - X-ray film Ni ₅₇ Nb ₄₃ . Sharp diffraction peaks correspond to a copper substrate.

FIG. 2 - A family of local current-voltage characteristics with different loads for the artificial oxide film Ni-Nb. The curves are stably reproduced during measurements in different places of the film.

FIG. 3 - X-ray photoemission spectroscopy spectra for pure Nb; line: Nb 3d. Dotted line: experimental data; Solid line: calculation.

FIG. 4 - X-ray photoemission spectroscopy spectra for artificial Ni-Nb oxide; line: Nb3d. Dotted line: experimental data; Solid line: calculation.

The invention is carried out as follows: a thin film with the composition described by the formula Nb _x Ni _100-x (where x = 40-60 at.%) Is obtained by magnetron sputtering on a copper water-cooled substrate at a speed of 50 nm / min with a magnetron power of 70 watts. When heated to a temperature of 200-300 ° C in an oxidizing atmosphere, Nb is completely oxidized to Nb ₂ O ₅ , and all of Ni goes under the oxidized surface. At the boundary between the oxide and Ni, an electron-deficient layer forms; the d-band of the Ni metal is less than half full. This leads to hole type conductivity. The choice of the temperature range and processing time is determined by the type of oxides that appear: below 200 ° C, natural niobium oxide remains, above 300 ° C nickel oxide appears. The effect can be used in the manufacture of elements of ultra-large integrated circuits as elements of complex diodes.

Example.

Alloy composition Ni ₅₇ Nb ₄₃ was obtained as follows.

Nickel and niobium with a purity of 99.9% were used to prepare the alloy. Melting was conducted in an electric arc furnace in an argon atmosphere. A target 2 mm thick and 50 mm in diameter was cut from the obtained ingot and subjected to magnetron sputtering on a copper substrate at a speed of 50 nm / min into a film 100 nm thick at room temperature.

The initial film structure was completely amorphous (Fig. 1). After that, the method of atomic force spectroscopy was used to measure local current-voltage characteristics with different cantilever clamping forces (Fig. 2). We used standard conductive cantilevers coated with a platinum layer with a radius of curvature of the probe tip of 20 nm. The samples were annealed in an oxidizing atmosphere of dry air at a temperature of 300 ° C for 30 minutes, which led to a significant change in the local current-voltage characteristics (Fig. 2) and hole conductivity was observed in the oxide film.

To explain the differences in the type of conductivity, we consider how the degree of oxidation of metals in the oxide layer changes. The oxidation state was determined using x-ray photoemission spectroscopy (Fig. 3-4).

When oxidized in dry air at 300 ° C, the higher oxide Nb ₂ O _{5 is formed} . At the boundary between the Nb ₂ O ₅ oxide and the electron-deficient Ni-Nb metal layer, a negative 3d shift of the Nb line is observed, which can be interpreted as a surface shift of the binding energy. The Ni d-band is not completely filled, as a result of which p-type conductivity appears. The estimated thickness of the oxide layer of Nb ₂ O ₅ 10.5 nm.

Schematically, the system can be considered as consisting of two Schottky barriers (Pt / NIO _x and NiO _x / NiNb metal matrix) separated by a tunnel barrier NiNb-oxide. The absence of conductivity at voltages less than 4 V from both polarities is due to the inability of the current to overcome the tunnel barrier. With an increase in the applied voltage, the barrier is suppressed, which allows charge carriers - holes - to flow through the system under study.

Claims (1)

A method of creating thin layers of hole and conductivity of Ni and Nb oxides for the manufacture of elements of ultra-large integrated circuits, which is to obtain a thin amorphous film with the composition described by the formula Nb _x Ni _100-x (where x = 40-60 atomic%), by magnetron sputtering a water-cooled copper substrate at a speed of 50 nm / min with a magnetron power of 70 W and subsequent annealing of the film in an oxidizing atmosphere at a temperature of 200-300 ° C for 30-60 minutes.

Images