Method for plasma-assisted reactive electron beam vaporization

• US 5,614,248 A
• Filed: 05/30/1995
• Issued: 03/25/1997
• Est. Priority Date: 10/27/1992
• Status: Expired due to Fees

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Schiller, Nicolas, Zeissig, Gerhard, Neumann, Manfred, Kirchhoff, Volker, Schiller, Siegfried, Goedicke, Klaus
• Primary Examiner(s): PADGETT, MARIANNE L
• Application Number:
  US08/424,418
• Time in Patent Office: 665 Days
• Field of Search: 427/527, 427/529, 427/566, 427/567, 427/570, 427/576, 427/585, 427/596, 427/8, 427/10, 427/574, 204/192.1, 204/192.13, 204/192.16, 204/192.22, 204/192.23, 204/192.26, 204/192.27, 204/192.28, 204/192.29
• US Class Current: 427/8
• CPC Class Codes: C23C 14/0021 Reactive sputtering or evaporation
• CPC Class Codes: C23C 14/54 Controlling or regulating the coating process

Abstract

Certain non-optical characteristics and, in particular, mechanical characteristics are not measurable in situ in the industrial production of layers using plasma-assisted reactive electron beam vaporization, particularly if high demands are made on the hardness, wear resistance and barrier action, so as to be able to reproducibly apply the layers. The values of the optical layer characteristics are to be used as a control signal. In this method, immediately after the substrate has passed through the vaporizing zone, the reflection and/or transmission and absorption capacity are measured in the wavelength range Δ_k =150 to 800 nm and from this are determined the refractive index and optical absorption coefficient. These determined values are compared with an experimentally determined desired value. A control signal obtained therefrom, in the case of a constant reactive gas partial pressure, controls the plasma and maintains constant the optical characteristics of the layer. The method is used in the vapor-deposition of wear-resistance, hard layers or barrier layers, e.g. of metal oxide on glass, plastic and other materials, e.g. in the building industry for facade glass and in the packaging industry.

Claims

1. A method for coating a substrate with a layer having defined mechanical characteristics by plasma-assisted reactive electron beam vaporization producing a controllable plasma in a process zone between a vaporizing material and the substrate so as to deposit a coating layer on said substrate, and providing in situ measurement of optical characteristics of the coating layer deposited on the substrate, the method comprising the steps of:

experimentally determining a correlation between optical characteristics and mechanical characteristics of the coating layer;

measuring in a wavelength range Δ

_k =150 nm to 800 nm at least one of a reflection, transmission and absorption capacity of the coating layer on the substrate immediately after the substrate passes through a vaporizing zone;

separately determining from said measuring step a refractive index n and an optical absorption coefficient k;

deriving initial mechanical characteristics of the coating layer corresponding to said index n and said coefficient k;

comparing said derived initial mechanical characteristics with the defined mechanical characteristics to obtain a control signal; and

using the control signal to control operating parameters of the plasma in a case of a constant reactive gas partial pressure in such a manner that said measured optical characteristics of the coating layer are maintained constant to achieve the defined mechanical characteristics, and in a case of constant plasma parameters, using the control signal to control the reactive gas partial pressure in such a manner that the measured optical characteristics of the coating layer are kept constant to achieve the defined mechanical characteristics.

2. Method according to claim 1, wherein for ensuring a fundamental stability of a plasma generating source, an intensity of a plasma emission in the process zone is measured and an operation of the plasma generating source is regulated by regulating one of an electric power and gas flow.

3. Method according to claim 1, wherein the reactive gas partial pressure is regulated by regulating a reactive gas flow.

4. Method according to claim 1, wherein the reactive gas partial pressure is regulated by regulating a suction capacity of a vacuum pump.

5. A method according to claim 1, wherein the mechanical characteristics are related to at least one of a hardness, a wear-resistance, and a barrier action of said coating layer.

6. A method according to claim 1, further comprising the step of using one of a glass material and a plastic material as said substrate.

7. A method according to claim 1, further comprising the step of operating said plasma-assisted reactive electron beam vaporization at a coating rate of 0.5 μ

m/s.

8. A method according to claim 1, further comprising the step of operating said plasma-assisted reactive electron beam vaporization at a coating rate of about 800 nm/s.

9. A method for coating a substrate with a wear-resistant layer and/or a layer with barrier characteristics by plasma-assisted reactive electron beam vaporization producing a controllable plasma in a process zone between a vaporizing material and the substrate to be coated, and providing in situ measurement of optical characteristics of the coating layer deposited on the substrate, the method comprising the steps of:

measuring in a wavelength range Δ

_k =150 nm to 800 nm at least one of a reflection, transmission and absorption capacity of the coating layer on the substrate immediately after the substrate passes through a vaporizing zone;

separately determining from said measuring step a refractive index n and an optical absorption coefficient k;

comparing said values n and k with an experimentally determined value corresponding to a predetermined wear-resistant layer and/or a predetermined layer with barrier characteristics to obtain a control signal; and

using the control signal to control operating parameters of the plasma in a case of a constant reactive gas partial pressure in such a manner that said measured optical characteristics of the coating layer are maintained constant, and in a case of constant plasma parameters, using the control signal to control the reactive gas partial pressure in such a manner that the measured optical characteristics of the coating layer are kept constant.