DD203075A1 - PROCESS FOR REACTIVE DC PLASMATRON DISTORTION - Google Patents

Abstract

The invention relates to a method for reactive DC-Plasmatron Zerstaeuben for grozzflächige substrates such. Flat glass. The goal is to achieve a defined layer thickness distribution, and the task is to control the Zerstäubungsrate without mechanical apertures. According to the invention, the width of the discharge zone is varied at the target in accordance with the required atomization rate in such a way that the reaction gas is distributed along the discharge zone of the plasmatron in a distributed manner near the target.

Description

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Process for reactive DC-Plasmatron sputtering

Field of application of the invention

The invention is used in sputtering with extended sources of piasmatron, especially when large areas, e.g. Flat glass, coated.

Characteristic of the known technical solutions

Reactive DC Plasmatron sputtering is a well known vacuum coating process for producing thin films formed by the reaction of metal particles with the reaction gas on the substrate. Layer thickness distributions arise on the substrate, which are essentially dependent on the geometry of the plasmatron, i. the sputtering rate distribution, as well as the distance and the relative movement between plasmatron and substrate are dependent.

In order to achieve the required layer thickness distribution, correcting diaphragms are arranged between the coating source and the substrate. However, the use of correction diaphragms has the disadvantage that in the course of the coating, stray layers deposit on them, which due to their high internal mechanical stresses can flake off even after relatively short coating times. This deficiency has a negative effect, in particular in highly productive continuous coating plants, in which the uninterrupted coating times are determined by the target service lives. Depending on the arrangement can

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fall off from the correcting apertures vagrant layers on the target or on the substrate. As a result, flashovers or layer defects are caused which disturb the process flow and lead to the breakage of the coating.

It is also known to guide the reaction gas into the vicinity of the substrates by means of a special gas guidance system. This is intended to reduce the formation of compound layers on the target, increase the metal atomization rate at the target and the coating rate for the compound on the substrate. By reducing the bonding layer on the target surface reduces the flashover frequency. Another solution is the gas supply for the noble gas through openings in the target (DD-PS 150 480). To improve the gas separation between the target and the substrate, the attachment of getter surfaces for the reaction gas was also proposed. If they are used to create certain layer thickness distributions, then they have the same function and also the same disadvantages as the correction diaphragms.

Object of the invention

The aim of the invention is to provide a method for reactive DC-Plasmatron sputtering for extended Plasmatronquellen and large areas to be coated, in which a defined layer thickness distribution is achieved on the substrates. It should be eliminated the shortcomings of the known methods, which are essential especially at coating times that are in the order of the target life.

Explanation of the essence of the invention

The invention has for its object to provide a method for reactive DC-Plasmatron sputtering, in which the distribution of the sputtering rate on the extended target is controlled defined without mechanical Xorrekturb! Ends.

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According to the invention, the object is achieved in that the width of the discharge zone or the microscopic Eedekkung with connecting layers within the discharge zone is influenced by a defined pressure distribution of the reaction gas at the target so that the sputtering rate at each point of the target for a given layer thickness distribution on the target has the value necessary for the substrate.

In reactive DC-Plasmatron sputtering, the inhomogeneous distribution of the current density means that certain target areas, called the discharge zone, are free of macroscopic connecting layers. This achieves the typically high sputtering rate compared to conventional reactive sputtering. Within the discharge zone, naturally microscopically thin cover layers may exist which, however, do not impede the electron emission of the target surface. As the reaction gas pressure decreases / increases, the macroscopic and microscopic coverage of the target with interconnect layers increases in a direct and sometimes extremely sensitive relationship with the increase / Decrease in sputtering rate,

In contrast to known technical solutions, which are to keep the reaction gas from the target or to avoid the sorption of reaction gas and thus the formation of compound layers on the target by heating the same, the invention uses this effect. The total amount of reaction gas supplied is adjusted depending on the stoichiometry of the bonding layers on the substrate in a manner known per se. An expedient procedure is to introduce only a portion of the required reaction gas quantity, preferably 20 to 5Q ^c ß>, at the target and. to use for controlling the atomization rate.

Exemplary embodiment . ,

For the reactive coating of large-area, perpendicular to Plasmatronausdehnung moving glass substrates (heat radiation-reflecting discs) up to 2 m long Plasmatrons

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used. The discharge ring "consists essentially of two parallel, linear discharge zones, which are arcuately closed at the two ends of the target.When coating a 1.90 m wide glass pane at 200 nm distance from the target, a homogeneous distribution of inert gas and reaction gas is required The reaction gas is therefore introduced via a gas supply system in such a way that a lower reaction gas pressure is created at the ends of the plasmatron, thereby increasing the width of the charge zone there or reducing the microscopic connection layer coverage Finally, the sputtering rate is increased so that the film thickness on the entire substrate is constant The gas feed system consists of 46 pieces of 1.50 m long, thin (3 mm inner diameter) tubes whose reaction gas exit ends are distributed along the discharge ring Ind. In the middle target area, the tubes are arranged gleichabständig. Toward the ends of the target, the distances between the tubes are increasingly greater in accordance with the desired sputter rate increase.

Claims (2)

235861 6 invention claim 1. A method for reactive DC-Plasmatron sputtering in the noble gas-reactive gas mixture by locally controlled gas conduction in Beschitchungsraum, characterized in that the width of the discharge zone and / or their microscopic coverage with connecting layers is adjusted according to the required sputtering rate such that the reaction gas is distributed along the discharge zone of the Plasmatrons supplied near the target. 2. The method according to item 1, characterized in that only a portion of the total necessary for the reactive Beschientungsprozeß reaction gas amount, preferably 2QfO to 50fo, is supplied to the vicinity of the target.