US-12618140-B2 - Method for surface coating according to the sputtering principle

US12618140B2US 12618140 B2US12618140 B2US 12618140B2US-12618140-B2

Abstract

There is a method for surface coating using a plasma coating device. The plasma coating device has a vacuum chamber; at least one sputtering source arranged in the vacuum chamber with a target of a solid material; a substrate to be coated; and at least one carrier gas source opening into the vacuum chamber. The method has the following steps: evacuating the vacuum chamber and supplying a carrier gas stream from the carrier gas source to the target such that a plasma with ions from atoms of the carrier gas is produced. The plasma ions dissolve particles out of the solid material of the target, and the dissolved particles are supplied to the surface of the substrate. The carrier gas stream is discontinuously supplied to the target of the sputtering source by modulating the gas flow of the carrier gas stream.

Inventors

Marc Strämke

Assignees

ELTRO GMBH

Dates

Publication Date: 20260505
Application Date: 20240826
Priority Date: 20230911

Claims (16)

1 . A method for surface coating according to the sputtering principle using a plasma coating device, the plasma coating device comprising: a vacuum chamber adapted to be evacuated by a vacuum pump, at least one sputtering source arranged in the vacuum chamber with a target made of a solid material, a substrate to be coated in the vacuum chamber, and at least one carrier gas source opening into the vacuum chamber, which is configured to produce a carrier gas stream directed towards the sputtering source, comprising the following steps: evacuating the vacuum chamber, supplying a carrier gas stream from the carrier gas source to the target such that a plasma with ions from atoms of the carrier gas is produced inside the vacuum chamber in an area of the target, wherein the plasma ions dissolve particles out of the solid material of the target and the dissolved particles are supplied to the surface of the substrate as a particle flow, wherein the carrier gas stream is discontinuously supplied to the target of the sputtering source by modulating the gas flow of the carrier gas stream without increasing an average gas flow of the carrier gas stream over time.
2 . The method according to claim 1 , wherein the carrier gas flow is modulated by varying an amplitude of the carrier gas flow.
3 . The method according to claim 1 , wherein the modulation is carried out in recurring phases such that an amplitude of at least one phase of the carrier gas flow is increased or reduced by at least a factor of 3 compared to an amplitude in another phase.
4 . The method according to claim 1 , wherein the modulation of the carrier gas flow with a modulation frequency is carried out such that a pressure inside the vacuum chamber does not increase by more than 50% during a period of the modulation.
5 . The method according to claim 1 , wherein the modulation of the carrier gas has a frequency is larger than 0.1 Hz.
6 . The method according to claim 1 , wherein the carrier gas flow is modulated by actuating at least one valve in a supply line of the carrier gas source.
7 . The method according to claim 1 , wherein the plasma coating device comprises several sputtering sources, wherein the carrier gas stream supplied to each sputtering source is modulated.
8 . The method according to claim 1 , wherein each sputtering source has an assigned separate carrier gas source, and wherein the carrier gas stream of each carrier gas source is supplied to the respective sputtering source.
9 . The method according to claim 1 , wherein the plasma coating device further comprises a reactive gas source opening into the vacuum chamber, from which a reactive gas is supplied to the vacuum chamber, which reactive gas reacts inside the vacuum chamber with a particle stream produced by the carrier gas.
10 . The method according to claim 1 , wherein the vacuum chamber is evacuated during surface coating to a pressure of less than 0.4 mbar.
11 . The method according to claim 1 , wherein the method is carried out according to the principle of cathode sputtering, and wherein the target forms a cathode.
12 . The method according to claim 1 , wherein the vacuum chamber has a housing that forms an anode and the substrate forms another cathode.
13 . The method according to claim 1 , wherein each sputtering source is configured as a hollow cathode.
14 . The method according to claim 1 , further comprising an electrical supply of the sputtering source and/or of the substrate that is modulated.
15 . The method according to claim 1 , wherein the surface coating is carried out by a magnetic sputtering method or according to the principle of ion beam sputtering, atom beam sputtering, high-frequency sputtering or direct current sputtering.
16 . The method according to claim 1 , wherein the carrier gas stream is supplied during surface coating at a velocity increased in phases without increasing the average velocity of the carrier gas stream.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority under 35 U.S.C. § 119 to German patent application DE 10 2023 124 377.2, filed Sep. 11, 2023, the entire disclosure of which is incorporated herein by reference. BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure The disclosure relates to a method for surface coating according to the sputtering principle using a plasma coating device. 2. Description of Related Art In plasma coating according to the sputtering principle, also referred to as “sputtering”, a solid, referred to as a target, is evaporated, which solid can be a metal, for example, thereby producing a plasma to deposit particles of the solid on a substrate, thereby coating the substrate. SUMMARY OF THE DISCLOSURE A plasma coating device for surface coating according to the sputtering principle comprises a vacuum chamber which is evacuated by a vacuum pump and in which the substrate to be coated is placed. At least one sputtering source comprising a target made of a solid material is disposed in the vacuum chamber. In a method referred to as “gas flow sputtering”, a carrier gas supplied to the vacuum chamber is used for sputtering. The carrier gas is usually a noble gas, such as argon. For this purpose, the plasma coating device comprises at least one carrier gas source opening into the vacuum chamber, with which a carrier gas stream directed towards the sputtering source is produced. A plasma is produced from atoms of the carrier gas in the area of the target. The ions of the plasma dissolve particles out of the solid material of the target. The dissolved particles are supplied to the surface of the substrate as a preferably directed particle flow, so that the particles are deposited on a surface of the substrate and form a layer thereon. The coating of surfaces according to the sputtering principles typically requires a low pressure in the coating space, i.e. within the vacuum chamber, to enable collision-free transport of the produced vapor onto the substrate. Higher pressures lead to the formation of larger particles and to a scattering of the vapor in all spatial directions and thus to material loss. Gas flow sputtering using a carrier gas is described in DE 42 10 125 C2, for example. In addition to cathode sputtering, arc evaporation is used for coating in prior art. In this respect, it is advantageous to generate a current of charged particles which lead to improved layer properties and increased layer adhesion in the coating process. Furthermore, prior art describes the superimposition of the discharge with a magnetic field in case of a glow discharge to increase the current density (“magnetron sputtering”). To increase the degree of ionization during magnetron sputtering, EP 1 038 045 B1, for example, describes a method referred to as high-power impulse magnetron sputtering (HIPIMS), in which the discharge is electrically modulated with the aim of increasing the current density and thus the degree of ionization. EP 1 038 045 B1 describes the modulated discontinuous supply of a reactive gas to the vacuum pump. In gas flow sputtering, an increase in the carrier gas flow leads to an increase in the deposition rate. However, high carrier gas velocities require particularly powerful vacuum pumps to maintain the required vacuum pressure inside the vacuum chamber. Against this background, the object of the present disclosure is to provide an improved method for surface coating according to the principle of gas flow sputtering with high deposition rate. The method according to the disclosure is defined by the features of claim 1. Accordingly, the surface coating is carried out with a plasma coating device, comprising: a vacuum chamber adapted to be evacuated by a vacuum pump,at least one sputtering source arranged in the vacuum chamber with a target made of a solid material,a substrate to be coated in the vacuum chamber, andat least one carrier gas source opening into the vacuum chamber, which is configured to produce a carrier gas stream directed towards the sputtering source. According to the method of the disclosure, the vacuum chamber is evacuated and a carrier gas stream is supplied from the carrier gas source to the vacuum chamber to the target such that a plasma with ions from atoms of the carrier gas is produced inside the vacuum chamber in the area of the target (“gas flow sputtering”), wherein the plasma ions dissolve particles out of the solid material of the target and the dissolved particles are supplied to the surface of the substrate as a particle flow, preferably in a directed manner. The dissolved particles are thus deposited on the surface of the substrate where they form a layer. The peculiarity of the disclosure is that the carrier gas stream is discontinuously supplied to the target of the sputtering source by modulating the gas flow of the carrier gas stream. This means that the carrier gas is supplied with modulated gas flow. Whereas conventionally