DD284486A5 - PROCESS FOR PREPARING DEFECTIVE, PLASMA-ASSISTED SEPARATE LAYERS - Google Patents

Abstract

The invention relates to a method for producing low-defect, plasma-deposited layers. The invention is used in particular where defects within the layer are to be avoided by deposits or installation of tinsel or dust particles from the working space. The invention has for its object to provide a method in which the continuous and unavoidable deposits on the Plasmabegrenzungsflaechen and installations in the plasma chamber adherent, so that no unwanted spalling occur that affect the actual coating process of the substrates unfavorable. According to the invention, the object is achieved such that during the coating a negative voltage which has a value of 50-90% of the substrate voltage is applied to at least part of the plasma chamber. {Plasma coating; Plasma chamber; Deposition, adherent; defects; Substrate voltage; Cleaning}

Description

Field of application of the invention

The invention relates to a method for producing low-defect, plasma-supported deposited layers. The invention is used in particular where defects within the layer are to be avoided by deposition or incorporation of flake or dust particles from the working space.

Characteristic of the known state of the art The plasma-assisted layer deposition is known in many variants. According to their mechanism, the Processes in plasma CVD (chemical vapor deposition) and plasma PVD (physical layer deposition)

distinguished.

In the case of thin plasma CVD processes, the goal is to form the plasma polymer layers or the corresponding ones

to deposit modified decomposition products on the partially lying also at a negative potential substrate. The

Specificity of the plasma processes leads forcibly but also for the coating of all the plasma space limiting other Components with condensates or polymers. These undesirable coatings are particularly troublesome when

they accidentally peel off or be rinsed by gas streams, get into the plasma chamber and on the layer structure at

Substrate act. In this case, disturbing defects in the layer arise. It is similar in the plasma PVD method. The only partially ionized steam jet knows! considerable quantities Neutral particles, which are also deposited on the plasma barriers and other components. Also these deposits

are not very adherent, can flake off and get on the substrates disturbing. In the case of all plasma processes, therefore, there is the permanent task of producing the unwanted deposits on the plasma walls or built-in components from the ones to be produced

Keep layers on the substrates. The simplest means is the constant intensive and expensive cleaning of the system before each batch. Deposits to the Plasma walls that are formed during the coating can still have a damaging effect on the coating. In the DD-WP210080 a solution is provided which provides a lining of the plasma chamber with a metal foil. This is not the plasma chamber coated as a stable component, but only the film, the technological rhythm

is replaced. The disadvantage here is the material and time required by changing the film.

Attempts have also been made to concentrate the plasma within the vacuum chamber in a narrow space,

to avoid the high expense of cleaning the vacuum chamber.

In EP140125 a flushing device is described in which by means of a focusing device is attempted, the plasma

to focus on a space between the target and the substrate. Only an incomplete spatial demarcation is achieved with respect to the Vakuumxammerwandungen so that sputtered particles can achieve this and unwanted

Deposits lead, which flake off after some time. JP58-164782 indicates a solution with which the depositions occurring should not flake off. These are the Chamber walls lined with a tissue. Thus, the unwanted deposited layer is heavily structured, has

thus less residual stress and does not burst so easily. The disadvantage here is the high cleaning effort after some time with still existing imperfection. Deposits of neutral particles can be whirled up even with slight gas flows and the covering of all complicated installations in the plasma chamber is hardly possible.

The DD-WP141168 provides a solution in which the plasma space from the coating chamber through a separate vessel

which has a positive potential with respect to the recipient is separated. The layer deposition takes place on the

Ground lying, d. H. negatively biased substrates. Also in this solution it comes to the deposition of evaporated Neutral particles, or substances decomposed in the plasma, without coherent layer formation on the positive Vascular walls with the consequences already described. Object of the invention The invention has the goal of effectively producing low-defect layers by means of plasma-assisted coating methods. Explanation of the essence of the invention

The invention has for its object to provide a method in which the permanent and unavoidable deposits on the plasma boundary surfaces and internals in the plasma chamber adherent, so that no unwanted spalling occur, which adversely affect the actual coating process of the substrates. According to the invention, the object is achieved in such a way that during the coating, a negative voltage is applied to at least part of the plasma chamber, which has a value of 50-90% of the substrate voltage.

With this process according to the invention, the unwanted layer deposits, similar to the substrate whose coating is not affected by the method according to the invention, deposited under ionic action and thus typically correspondingly tight and adherent. This has the consequence that these unwanted layers do not flake off or only at large layer thicknesses and thus cause no damage to the substrate layer. The selective adjustment of the potential of the plasma boundary surfaces, between 50-90% of the substrate potential, allows a targeted effect on the density and adhesion of this layer depending on the type of substances used. In particular, the potential number of batches can thus be optimized until the next time the plasma chamber is cleaned, ie. H. as many batch coatings as possible without spalling while still offering relatively good cleaning options. Furthermore, if the plasma chamber is made optically dense, almost no neutral particles can deposit on the recipient wall, and the cleaning of the recipient is largely unnecessary. Depending on the substances present and the plasma parameters, it may also be sufficient to apply the voltage to the plasma chamber, or the parts thereof and the internals, only in pulses. In this case, the simple deposits are subsequently adhered to the substrate by the subsequent pulse-like ion bombardment. With this process variant, a considerable energy saving can sometimes be achieved. If, in the course of the plasma-assisted coating, the substrates are cleaned prior to coating with ion bombardment, then it is advantageous to place the plasma chamber or parts thereof at the same voltage as the substrates, so that the same cleaning effect, especially of contamination, also occurs. With the process control according to the invention, it is possible for a long time, or many batches without cleaning the plasma chamber, to prevent any spalling or whirling of undesirable deposited on the plasma boundary walls substances without the actual film formation process is affected on the substrate.

Ausführungsbelsplel Below, the invention will be explained in more detail by way of example. A 14 "-Magnetspeicherplatte as a substrate is for the purpose of wear and corrosion protection on both sides with an approximately

100 nm thick iC layer (hard ion-supported deposited carbon) to coat. The layer must be uniform

Layer thickness and they must not show any defects due to foreign inclusions or defects. The stratification

carried out by the process of plasma coating. There is a hydrocarbon gas, e.g. Benzen, introduced into the plasma zone within a recipient and decomposed in the plasma. In this case, carbon is deposited on all adjacent surfaces. Ancestry-typical, a negative potential is applied to the substrate, so that there runs off the carbon deposition with simultaneous ion bombardment and deposits a hard iC layer.

In the example, the substrate is arranged on a substrate carrier, which is centered in the recipient between two Plasma sources is located. Substrate carriers and plasma sources are radially surrounded by a cylindrical radial shield,

which acts as a plasma chamber. "According to obc η, the plasma chamber is bounded by a plasma cover and at the bottom of the bottom of the plasma chamber

Recipients. In this arrangement, it is particularly the deposits on the upper plasma cover that reach the substrates

can and cause disturbances there. Therefore, the plasma covering method of the present invention is applied and a potential of 80% of the substrate potential is applied.

In the example, to achieve a hard iC layer, -500V is applied to the substrates. To the plasma cover

-400 V applied. In this procedure, without the layer structure is affected on the substrate, takes place at the

Plasma coverage, the inevitable carbon deposition also under ion action, but less than on Substrate. In contrast to the layer on the substrate, which is adherent and hard deposited, the layer deposition takes place

the upper plasma coverage at -400 V bias adherent but with relatively low hardness, so that there is no unwanted delamination. Anriarprseits the layer after some time, which is about a factor of 10, are relatively easy to remove.

With this procedure, magnetic storage disks in series operation without the occurrence of impurities by Foreign inclusions are produced with good effectiveness.

Claims (3)

1. A method for producing low-defect, plasma-supported deposited layers within a coating chamber, characterized in that during the coating, a negative voltage is applied to at least a portion of the plasma chamber, which has a value of 50 to 90% of the substrate voltage. 2. The method according to claim 1, characterized in that the negative voltage is applied pulse-like to the plasma chamber. 3. The method according to claim 1, characterized in that, during the ion bombardment of the substrates, the voltage across the plasma chamber is up to 100% of the substrate voltage.