DE102012110927A1 - Vacuum processing of substrates for treating substrate, comprises igniting magnetron discharge by supplying e.g. inert working gas, displacing first plasma zone, igniting additional magnetron discharge and concentrating second plasma zone - Google Patents

Abstract

Vacuum processing of substrates for treating a substrate (1) by a plasma device, comprises: igniting a magnetron discharge by supplying inert working gas and reactive gas; displacing first plasma zone (5) on a self-contained web over the substrate; igniting an additional magnetron discharge within the dark-field shielding; and concentrating the second plasma zone on the surface of the substrate facing the counter electrode by a second magnet system, which is associated with the counter electrode. The pair of electrodes is operated with a voltage. Vacuum processing of substrates for treating a substrate (1) by a plasma device, which comprises a magnetron electrode having a first magnet system (4) and electrode disposed adjacent to a substrate, a substrate as an electrode which are collectively referred to a substrate electrode (2), at least one counter electrode, and a dark-field shield for limiting the extent of plasma, comprises: igniting a magnetron discharge by supplying inert working gas and reactive gas; displacing first plasma zone (5) on a self-contained web over the substrate; igniting an additional magnetron discharge within the dark-field shielding; and concentrating the second plasma zone on the surface of the substrate facing the counter electrode by a second magnet system, which is associated with the counter electrode. The pair of electrodes is operated with a voltage, such that the plasma burns alternately across the substrate and the counter electrode. An independent claim is also included for a device for vacuum processing of substrates with a plasma device, comprising a magnetron electrode comprising a first magnetic system, electrode disposed adjacent to a substrate, a substrate as an electrode which are collectively referred to substrate electrode, at least one counter electrode, a power source for the counter electrode and/or the electrode or the substrate electrode, a dark field shield for limiting the plasma expansion, and a gas supply means for supplying working gas or reactive gas. The dark-field shield and a second magnet system having at least a north and a south pole are disposed after the counter-electrode, which is on the a substrate side remote from the concentration of plasma on the surface of the counter electrode.

Description

The invention generally relates to a plasma-assisted process for the vacuum treatment of substrates. In particular, it relates to a treatment method in which a plasma is ignited by means of a plasma device with supply of inert working gas or under supply of inert working gas and reactive gas, the plasma zone is forced to a self-contained path over the surface to be treated of the substrate. The plasma device comprises a magnetron electrode with a first magnet system and with an electrode arranged adjacent to the substrate or with a substrate as electrode, both of which are collectively referred to as substrate electrode, at least one counter electrode and a dark field shield for limiting the plasma expansion.

The invention also relates to a device for carrying out such a method.

Different substrates, for example for architectural or photovoltaic applications are subjected to different treatments. As treatment, the known modifying, additive and subtractive treatments should be understood here, i. Processes in which the effect of a plasma burning over the substrate is used to structurally or energetically alter the substrate or layers present on the substrate, to deposit material on the substrate or to remove it from the substrate. The term "plasma above the substrate" or "on the substrate" generally refers to that basic process variant in which the substrate to be treated is directly exposed to the plasma, in contrast to the spatial separation between plasma generation and substrate (remote method).

In addition to the substrate coating with different layers and layer systems, the process described below is understood to mean, for example, plasma treatments or sputter etching. The latter method can also be supported by appropriate reactive gases, wherein the device used for this purpose can also be carried out by PECVD when precursor gases are introduced. It is also possible to influence the layer properties of a layer to be deposited by a suitable method by means of a magnetron discharge near the substrate.

The treatment takes place in large-scale industrial plants in one pass and thus in a vacuum sequence, whereby different treatments can be required in succession in one pass.

For the plasma-assisted vacuum treatment of substrates, a plasma is ignited by means of the electrode arrangement in a vacuum with the aid of a working gas, and the electrons are enclosed by means of a magnetic field provided by a magnetic system at the cathode. As is known, such a magnet system is arranged on the side of the cathode facing away from the plasma and consists of a central magnetic pole which surrounds a second, opposite magnetic pole in an annular manner, so that magnets with locally alternating polarity, viewed in cross-section, are arranged next to one another. Due to the thus formed as a ring, tunnel-shaped magnetic field, the plasma zone over the gap between two magnetic poles, where the magnetic field lines are parallel to the target surface, concentrated and form a self-contained plasma ring.

The positive charge carriers of the plasma cause the so-called sputtering effect by which the upper layers of a surface, a substrate or a target are removed. Depending on the method, the counter electrode opposite to the substrate electrode cathode or anode. In the deposition of layers, the substrate to be coated may be placed at relative (with respect to the potential of the other electrode) anode potential, while it is at the removal of layers or impurities or surface activation at a relatively cathode potential.

A device which can be used for this purpose generically comprises a plasma device which has a magnetron electrode with a substrate electrode, at least one counterelectrode over the substrate electrode, a power supply for at least one of the electrodes, a dark field shield for limiting the plasma expansion and a gas supply device optionally having a plurality of gas inlets for the supply of Working gas or reactive gas or working and reactive gas.

The counter electrode is often plate-shaped or box-shaped. In order to prevent unwanted discharges, eg to the chamber wall when the substrate electrode is grounded, earthed shields are used. Such dark field shields must be so close to the parts to be shielded that their distance is less than the time required for firing the discharge length of the dark space in front of the electrode surface. Such a dark field shield of an anode box used for dry etching is, for example, in U.S. Pat DE 10 2008 023 027 A1 described.

In the named treatment method, the above the substrate electrode burning Magnetron charge often operated so that the substrate electrode and the counter electrode alternately serve as the cathode and the anode of the discharge. In this way it should be prevented that the unintended on all components of the treatment device and in particular on the counter electrode layer deposition interferes with the process or brings to a standstill. Due to the alternating wiring, an uncoated counterelectrode should be available for as long as possible. However, it has been found that such reverse polarity of the discharge is not effective to free sputtering of the counter electrode.

The invention is therefore based on the object of specifying a method and a device which can be used for this, which permit long-term stable operation of the generic objects, even in the deposition of insulating layers by reactive and CVD processes.

According to the invention, a further plasma is ignited within a dark field shielding of a counterelectrode which burns on the surface of the counterelectrode facing the substrate by a further magnetic field. For this purpose, behind, i. the side facing away from the substrate of the counter electrode another magnet system arranged with at least one north and one south pole. Thus, the counter electrode is in a magnetic field, which is sufficiently strong enough to stably ignite and obtain a further magnetron discharge in front of the counter electrode.

According to the invention, this further discharge is operated alternately with the discharge across the substrate by a suitable voltage control. According to one embodiment of the method, a pulsed or sinusoidal alternating voltage is applied to the counterelectrode for the alternating discharge, so that in one sub-period the magnetron discharge burns over the substrate and in the subsequent subperiod over the counterelectrode. The term "above" describes a position relative to the substrate, which faces the process area and thus that plasma area which serves for the substrate treatment. Depending on the position of the substrate, this may differ from a horizontal reference.

Also, as is known from the magnetron targets for sputtering, the magnet system of the counterelectrode is designed in such a way that an annular plasma zone is formed above the counterelectrode so that a racetrack, i. a racetrack-shaped erosion trench according to the course of the strongest parallel component of the magnetic field, on the counter electrode is stable and controllable and controllable form. By separating the two processes, the one above the substrate and that for removing layers above the counter electrode, the influence of this complementary plasma zone on the actual treatment process and the cleaning effect for the counter electrode can be influenced in a targeted manner.

This supplemental magnetron discharge also allows for very low pressure ranges, e.g. used in magnetron sputtering, the removal of surface layers on the counter electrode for significantly longer operating times, as with the known methods. In addition, the additional discharge in the treatment area leads to an increased plasma density and thus to an effective treatment.

The named effects can be used in addition to various methods for plasma or sputter etching, in particular also for coating methods by means of PECVD, in which the layer growth on the components of the device is very high. In addition, the process according to the invention can also be used with the addition of reactive gas for those processes in which the reactive gas serves to effectively remove certain layers. Thus, a plasma assisted pretreatment process is e.g. Oxygen supplied, which in particular organic layers or contaminants are easy to remove.

The inventive method is applicable for different potential conditions. Thus, the electrode voltage of the counter electrode can be operated with respect to ground potential. According to one embodiment of the invention, the substrate electrode may be at ground potential and the potential of the counter electrode may be the only one, other potential, relative to ground. If the counter electrode is operated opposite another potential, the dark field shield includes further measures to prevent spread of the plasma discharge to the chamber wall or other grounded components of the treatment device. For example, a shielding immediately below the substrate electrode is advantageous for such potential conditions.

According to one embodiment of the method, the plasma zone is annularly operated on the counterelectrode in such a way that it encompasses the plasma zone above the substrate, lying above it. For this purpose, the counterelectrode and its magnet system, both of which lie above the substrate electrode within the space lying in the dark field shielding, can be designed to surround the magnet system of the magnetron electrode in a ring-like manner when viewed in plan view. In this case, the magnet system can be formed in one or more parts. Such an arrangement allows one homogeneous circumferential plasma zone, which can avoid areas of poorer material removal.

If, according to a further embodiment of the method, the power components attributable to the substrate electrode and counterelectrode are set with an applied alternating voltage by a superimposed DC voltage or pulse voltage by pulse height and / or pulse duration, the treatment processes on the substrate and on the counter electrode of the respective situation in the treatment chamber and to be adapted to each other.

In one embodiment of the treatment device, the counter electrode is arranged at an angle of its electrode surface of equal to or greater than 90 ° to the substrate. Such an inclination of the counter electrode away from the substrate prevents the sputtered from the counter electrode material is dusted in the direction of the substrate. Thus, an influence on the treatment of the substrate can be avoided by this material or at least significantly reduced. It is often sufficient that the plasma-exposed surface of the counter electrode has an angle between 90 ° and 100 ° to the substrate surface. Of course, larger angles can be advantageous.

In addition, diaphragms which delimit the exposed surface of the substrate, e.g. be arranged on the surface of the burning thereon magnetron discharge, keep away from the counter electrode sputtered and / or scattered particles from the substrate.

In a further embodiment of the invention, the magnet systems of both electrodes can be arranged such that the north pole of one electrode faces the south pole of another electrode. In this way, a magnetic barrier for the electrons of the plasma and thus for the plasma is formed, which bridges the lateral space between the substrate electrode and the overlying counter electrode. Thus, burn-out of the plasma from the space above the substrate electrode can be suppressed and the usable parameter range of the process parameters of the treatment area can be increased. For example, methods with higher gas pressures and / or greater distances between the counter electrode and the substrate electrode, for example for curved substrates or comparable applications of the invention, can be stably realized, for example on treatment devices in which a belt-shaped substrate is treated during its travel via a drum or roller ,

If, in a further embodiment of the device, the gas supply device has a working gas inlet spatially above the counterelectrode and a suction in the substrate environment, i. Under the counter electrode, in addition, a flushing of the counter electrode by the working gas and thus to achieve the reduction of the deposits on the counter electrode. In addition, an increase in concentration of the reactive gas or precursor can be achieved from the counter electrode to the substrate. The latter is favored in particular by an inlet of the reactive gas or precursor close to the substrate, which is e.g. can be realized by means of directed to the substrate nozzles.

In addition or as an alternative to the described embodiments of the device, the counterelectrode may be designed in such a way that it is electrically divisible. This makes it possible to select one or more regions of the counterelectrode for locally differentiated variation of the treatment process, which actively participate in their magnetron discharge and / or which are at a differentiable potential. Such a locally differentiable treatment process allows the formation of treatment profiles over the substrate surface or their compensation if they are undesirable.

According to a further embodiment of the device, the counterelectrode may at least partially comprise a material which exerts a beneficial effect on the substrate treatment. For this purpose, portions of the counter electrode may consist of this material or be coated with this material. Such an advantageous effect may e.g. a purely technologically related material component, which alone or primarily relates to the process implementation and thus has only an indirect effect on the surface quality of the treated substrate. However, it is also possible to use materials which precipitate on the substrate and thus have a direct influence on the treatment result. By way of example only, without limitation, mention may be made of titanium as a primer which may be applied to the substrate simultaneously with substrate pretreatment. Or an aluminum counter electrode is used in a PECVD process where aluminum oxide is to be deposited.

In a further embodiment, the substrate electrode can be formed as a perforated electrode, for example a screen plate. By their arrangement adjacent to and above the substrate burns on the counter electrode facing surface of the sieve electrode plasma. The ions are accelerated towards the sieve electrode, pass partially through it, continue to move towards the substrate and cause their on the substrate kinetic energy an etching effect. In this way it is possible, for example, to extract ions for the CVD or sputtering process.

The described method and apparatus are applicable to the various embodiments in the continuous process. Various pass-through machines are known in which the substrates are standing or lying, with or without a substrate holder, by means of a transport device or in the case of belt-shaped substrates, via a system of rollers, drums and rollers by a, e.g. arrangement of chambers from an entrance lock to an exit lock and between at least one process chamber and at least one substrate treatment device, such as a coating or etching device are moved uniformly in a Substrattransportrichtung over. Likewise, the technical solutions described are applicable to single-end systems in which the substrates are introduced into the system through a lock, transported back through at least one process chamber past at least one substrate treatment device and back to the lock through which the substrates finally pass also leave the plant again.

The invention will be explained below with reference to exemplary embodiments. The accompanying drawing shows in

1 a treatment room for carrying out the method according to the invention,

2A . 2 B Variants of the wiring of the electrode arrangement,

3 An embodiment of the device according to the invention with a substrate electrode arranged adjacent to the substrate and

4 a further embodiment of the device according to the invention with perforated return plate of the magnet system.

In 1 Fig. 12 is a processing apparatus used for plasma etching in the presence of a reactive gas and disposed within a vacuum chamber (not shown).

The treatment becomes a substrate 1 by means of a transport device, the successive rolls 17 below the substrate 1 has, in a transport direction 3 transported through the device and treated. The substrate 1 is at ground potential and used with respect to the counter electrode 8th as a substrate electrode 2 ,

The device further comprises a first magnet system 4 for generating the first annular plasma zone 5 the magnetron discharge over the substrate 1 , The first magnet system 4 includes for this purpose a central north pole N, which is annularly enclosed by a south pole S. Above the poles, a self-contained magnetic tunnel is formed whose magnetic field lines 6 are shown by dashed lines.

Above the substrate 1 , in the region of said first magnet system 4 , is a trough-shaped, to the substrate 1 towards open anode box 7 arranged. The anode box 7 includes the arranged in its interior, electrically with the anode box 7 connected counterelectrode 8th circulating and with some angles deviation parallel to the sidewalls of the anode box 7 runs. The counter electrode 8th encloses the through the first plasma zone 5 above the substrate 1 continuous treatment area formed. The anode box 7 and thus the counterelectrodes 8th are with a power supply 9 connected, which puts both on positive high voltage potential, so that the counter electrode 8th as the anode and the substrate 1 in the embodiment as a substrate electrode 2 serves as the cathode of the plasma discharge acts.

The possible wiring of the counter electrode 8th by means of the power supply 9 is in 2A and 2 B represented by the voltage-time characteristic. Accordingly, the feeding of the discharge current is carried out either via a sinusoidal AC voltage ( 2A ) or a pulsed AC voltage ( 2 B ) of the counter electrode 8th opposite to the substrate electrode 2 as a mass.

The outside of the anode box 7 is from a likewise trough-shaped shielding box 10 envelops. The distance of the shielding box 10 to the anode box 7 everywhere is smaller than the darkening field length which arises at the prevailing process pressure in the working gas. The shielding box 10 is at a distance of a few centimeters above the substrate 1 arranged and is the substrate through an aperture 11 completed.

On the aperture 11 at her to said first plasma zone 5 pointing edge another gas inlet 12 arranged, which is the supply of reactive gas, for example oxygen, and a plurality of distributed over the width of the substrate nozzle-like outputs. The outputs are towards the substrate 1 directed, so that the reactive gas (represented by arrows) to the substrate 1 and through the first plasma zone 5 flows.

Inside the anode box 7 is an axially located gas inlet 12 for the working gas of the process, such as argon, formed whose output above a baffle plate 13 empties. The baffle plate is above the counter electrode 8th close to the wall of the anode box 7 and substantially parallel to the substrate 1 such that incoming argon gas (represented by arrows) laterally towards the counter electrode 8th distributed and made available to the process.

In the gap between the panel 11 and the substrate 1 is a suction 14 arranged, which comprises a plurality of lamella-shaped baffles, which are substantially parallel to the aperture 11 and to the substrate 1 run. Due to the location of the baffle plate 13 the gas inlet 12 and the suction 14 the working gas is at the entire counter electrode 8th passed and rinsed with it. This flushing action of the counterelectrode can be realized in addition to the generation of the process gas by the described introduction of the working gas above the counterelectrode and the reactive gas near the substrate in connection with the suction near the substrate.

The shielding box 10 , the aperture 11 , the fins of the suction 14 and the flapper 13 are at ground potential. Alternatively, these components may also be designed floating.

Inside the anode box 7 is behind the counter electrode 8th and thus by the counter electrode 8th the substrate 1 concealed and within the dark field shielding of the shield box 10 a second magnet system 15 arranged. It has one along the counter electrode 8th around the first plasma zone 5 extending north pole N and a parallel extending south pole S on. Due to this circumferential arrangement of the two poles of the second magnet system 15 an encircling magnetic field tunnel (magnetic field lines shown in dashed lines) forms and therein at each circuit of the counter electrode 8th as cathode, a second plasma zone 16 , The second plasma zone 16 includes the first plasma zone 5 extensively.

The north pole of the second magnet system 15 lies the substrate 1 facing and thus the south pole of the first magnet system 4 opposite, so that a magnetic field between these two poles and thus forms lying in front of the suction. This magnetic field (magnetic field lines shown in dashed lines) serves as a magnetic barrier to the charge carriers such as electrons of the plasma discharges, as described above.

To perform the treatment, a plasma alternately turns into a sub-period of a period of the AC voltage across the substrate 1 and over the counter electrode 8th ignited, namely where the magnetic field lines are parallel to the target surface, thus in each case centrally between two magnetic poles of each magnet system 4 . 15 , In these areas, the Abtragsoberflächen form, in which material from the surface of the substrate 1 and the counter electrode 8th is sputtered. In this way, there is always free electrode surface of the counter electrode 8th available for a stable process.

About the power supply, the treatment method according to the invention is to be linked in a known manner with a scheme. For this purpose, a measuring device that analyzes the substrate surface after the plasma treatment, connected via a control loop with the power supply of the discharge, so that on the one hand on the effective power in the positive half-wave or in the positive pulse and the reactive gas inlet, the desired layer property is kept constant. On the other hand, the effective power in the negative half-wave or in the negative pulse is adjusted so that disturbing impurities are minimized while monitoring the electrical discharge parameters.

3 represents an embodiment of the treatment device, in which the substrate electrode 2 separate to the substrate 1 and at a small distance above the substrate 1 is arranged. The substrate electrode 2 is formed like a sieve and lies like the rollers 17 and thus also the substrate resting on them 1 at ground potential. The electric field prevailing in the plasma chamber is formed such that the electric field lines in the region of the substrate electrode 2 perpendicular to the substrate electrode 2 stand. The magnetic field lines 6 of the first magnet system 4 and the second magnet system 15 proceed as above 1 described. The plasma burns on the counter electrode 8th facing surfaces of the substrate electrode 2 , The ions become the substrate electrode 2 accelerates, sometimes pass through them and cause on the substrate 1 by their kinetic energy an etching effect.

The device according to 4 has over the embodiment according to 3 the peculiarity of having the first magnet system 4 between the substrate electrode 2 and the substrate 1 is arranged, wherein the return plate of the first magnet system 4 Having openings through which the positive charge carriers to the substrate 1 to be accelerated.

LIST OF REFERENCE NUMBERS

1

substratum

2

substrate electrode

3

transport direction

4

first magnet system

5

first plasma zone

6

magnetic field lines

7

anode box

8th

counter electrode

9

power supply

10

shielding box

11

cover

12

gas inlet

13

flapper

14

suction

15

second magnet system

16

second plasma zone

17

roller

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008023027 A1 [0009]

Claims (14)

Method for the vacuum treatment of substrates, wherein for the treatment of a substrate ( 1 ) by means of a plasma device, which has a magnetron electrode with a first magnet system ( 4 ) and with one adjacent to the substrate ( 1 ) or with a substrate ( 1 ) as an electrode, both are summarized below as a substrate electrode ( 2 ), at least one counterelectrode ( 8th ) and a dark field shield for limiting the plasma expansion, and is ignited under supply of inert working gas or under supply of inert working gas and reactive gas, a magnetron charge whose first plasma zone ( 5 ) on a self-contained web over the substrate ( 1 ), characterized in that within the dark field shield ignited another magnetron discharge and the second plasma zone ( 16 ) by means of a second magnet system ( 15 ), which of the counter electrode ( 8th ), above which the substrate ( 1 ) facing surface of the counter electrode ( 8th ), wherein the electrode pair is operated with a voltage such that the plasma alternately over the substrate ( 1 ) and over the counter electrode ( 8th ) burns. Method for the vacuum treatment of substrates according to claim 1, characterized in that the pair of electrodes is operated with a pulsed or sinusoidal AC voltage, so that the plasma in a sub-period above the substrate ( 1 ) and in the subsequent sub-period over the counter electrode ( 8th ) burns. Method for the vacuum treatment of substrates according to one of the preceding claims, characterized in that the second plasma zone ( 16 ) on the counterelectrode ( 8th ) is operated ring-shaped in such a way that it blocks the first plasma zone ( 5 ) above the substrate ( 1 ) surrounds. Method for the vacuum treatment of substrates according to one of claims 2 or 3, characterized in that the substrate electrode ( 2 ) and counterelectrode ( 8th ) attributable power components with applied AC voltage by a superimposed DC voltage or pulse voltage by pulse height and / or pulse duration Method for the vacuum treatment of substrates according to one of the preceding claims, characterized in that the substrate ( 1 ) is coated by PECVD or treated by plasma or sputter etching. Device for the vacuum treatment of substrates with a plasma device, which has a magnetron electrode with a first magnet system ( 4 ) and with an electrode or with a substrate ( 1 ) as an electrode, subsequently as a substrate electrode ( 2 ), at least one overlying a substrate position counter electrode ( 8th ), a power supply ( 9 ) for the counterelectrode ( 8th ) and / or the electrode or substrate electrode, a dark field shield for limiting the plasma expansion and a gas supply device for working gas or working and reactive gas, characterized in that within the dark field shield and behind the counter electrode ( 8th ), that is on its one substrate ( 1 ) side facing away, a second magnet system ( 15 ) with at least one north and one south pole for the concentration of plasma over the surface of the counterelectrode ( 8th ) is arranged. Device for the vacuum treatment of substrates according to claim 6, characterized in that the electrode or the substrate electrode ( 2 ) is at ground potential. Device for the vacuum treatment of substrates according to one of claims 6 or 7, characterized in that the counterelectrode ( 8th ) and its second magnet system ( 15 ) in plan view, the first magnet system ( 4 ) of the magnetron electrode are annular and formed in one or more parts. Device for the vacuum treatment of substrates according to one of claims 6 to 8, characterized in that the counterelectrode ( 8th ) with an angle of its electrode surface of equal to or greater than 90 ° to the surface of a substrate to be treated ( 1 ) is arranged. Device for the vacuum treatment of substrates according to one of claims 6 to 9, characterized in that the first and the second magnet system ( 4 . 15 ) are arranged such that a north pole of the one magnet system faces a south pole of the other. Device for the vacuum treatment of substrates according to one of claims 6 to 10, characterized in that the gas supply device comprises a gas inlet ( 12 ) for working gas over the counter electrode ( 8th ) and a suction ( 14 ) in substrate environment. Device for the vacuum treatment of substrates according to one of claims 6 to 11, characterized in that the counterelectrode ( 8th ) is formed in such a multi-part, that it is electrically divisible. Device for the vacuum treatment of substrates according to one of claims 6 to 12, characterized in that the counterelectrode ( 8th ) at least in sections consists of a material that exerts a beneficial effect on the substrate treatment. Device for the vacuum treatment of substrates according to one of claims 6 to 13, characterized in that a substrate electrode ( 2 ) is formed as a perforated electrode.

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