DE102022000838A1 - System for producing at least one thinnest layer - Google Patents

Abstract

The invention relates to a system for producing at least one thinnest layer, the thinnest layer being formed from a gas phase deposited on a substrate. The invention is based on the object of providing a system with which the thinnest layers, such as graphene, can be manufactured very efficiently. This task is solved with a system of the type mentioned by the feature mentioned in the characterizing part of patent claim 1. According to the invention it is therefore provided that the substrate is arranged adjacent to at least one rotatably mounted roller.

Description

The invention relates to a system for producing at least one thinnest layer, the thinnest layer being formed from a gas phase deposited on a substrate.

The thinnest layer can consist of graphene, for example. Graphene is an allotropic form of carbon, which consists of a two-dimensional layer of carbon atoms arranged in a hexagonal lattice, similar to honeycombs. Graphene is increasingly being used as a semiconductor material and has unique optical, thermal and electrical properties. For example, graphene can be produced by mechanical exfoliation, chemical exfoliation using organic solvents, or chemical vapor deposition. Ideal graphene only has one atomic layer of carbon, but even a thin layer of graphene with two to ten atomic layers is still referred to as graphene. Alternatively, the thinnest layer can also be any other material that can be formed on a substrate by chemical vapor deposition, for example silicene or other materials made of atoms in a hexagonal lattice, for example boron and nitrogen or boron, nitrogen and silicon.

A system of the type mentioned at the beginning is, for example, from the WO 2020/187896 A1 known. There, a system for producing graphene on a substrate is shown, which has a chamber for providing a gas atmosphere. In the chamber there is a first substrate roll for the substrate before coating with graphene and a second substrate roll for the substrate after coating with graphene. The reaction zone in which the coating of the substrate with graphene takes place is arranged between the substrate rolls. The deposition of graphene from the gas phase takes place at atmospheric pressure. A mixture of carbon source gas, hydrogen and inert gas serves as the reaction gas. Methane, ethane, propane, ethene, propene, benzene, naphthalene or anthracene are mentioned in particular as possible carbon sources. In particular, argon, xenon, helium or nitrogen are suggested as inert gas. Various metals are suggested as materials for the substrate, such as nickel, cobalt, iron, platinum, gold, aluminum, chromium, copper, magnesium, manganese, molybdenum, rhodium, silicon, tantalum, titanium, tungsten, uranium, vanadium, zirconium, brass , bronze or steel.

After EP 3 632 846 A1 On the other hand, in order to form graphene by chemical vapor deposition, it is known to treat a surface of a substrate arranged in a reaction chamber with plasma while a voltage is applied to the substrate. According to this publication, a pressure of 0.02-5 Torr applies during vapor deposition. The plasma can be generated, for example, by a radio frequency generator (RF plasma) or by a microwave (MW plasma).

The invention is based on the object of providing a system with which the thinnest layers, such as graphene, can be manufactured very efficiently.

This task is solved with a system of the type mentioned by the feature mentioned in the characterizing part of patent claim 1.

According to the invention it is therefore provided that the substrate is arranged adjacent to at least one rotatably mounted roller. The roller is positioned relative to the substrate in such a way that the roller does not touch the substrate, but is arranged at a distance from the substrate. The roller is mounted so that it can rotate, so it can rotate. It is advantageous here if the roller is rotatable in such a way that a central axis of the roller is oriented parallel to the substrate and the distance of the central axis of the roller to the substrate remains constant during rotation.

The role is particularly advantageously designed to be subjected to an electrical potential to form a plasma. This means that in a system according to the invention, the plasma is preferably formed by a high electrical potential and not by applied microwaves, radio frequency or inductive coupling. Alternatively, a system according to the invention can also be designed in such a way that the plasma is generated by a microwave generator to form a MW plasma or by a radio frequency generator to form an RF plasma or by a coil to form an inductively coupled plasma or ICP.

Particularly advantageously, at least two rollers are provided, which are arranged in such a way that the substrate is positioned centrally between the rollers. Here too, the rollers are arranged so that they do not touch the substrate - even when rotating. In this case, both rollers can be subjected to an electrical potential to form a plasma, namely one role as an anode and one role as cathode, when DC voltage is applied to the rollers. Alternatively, alternating voltage can also be applied to the two rollers, whereby the two rollers can also be switched as opposite poles. This arrangement is particularly recommended if the substrate is band-shaped. Then the rollers, which can ideally be imagined as cylinders, can have one circumferential side parallel to each other be arranged on a flat surface of the band- or film-shaped substrate.

Alternatively, only one roller can be present, which according to the invention can also be subjected to an electrical potential, either direct voltage or alternating voltage. In this case, a housing of the system, for example, can serve as a counterpoint. On the other hand, a sheet metal can also be provided in the system, which can be subjected to electrical potential as a counterpole to the roller.

In the case of a band-shaped substrate, it is advantageous if the roller or rollers are shaped as a cylinder, with a base surface of the cylinder being oriented perpendicular to the substrate and a central axis of the cylinder being arranged parallel to the substrate. It is advantageous here if a height of the cylinder corresponds at least to the width of the substrate. The roll is therefore at least as wide as the substrate, ideally the roll is even wider than the substrate. This results in the plasma being formed across the entire width of the substrate, ideally even beyond it.

A metal foil, for example made of aluminum, chromium, gold, palladium, rhodium, vanadium or another metal, can serve as the band-shaped substrate. Alternatively, the substrate can also be a plastic film, for example made of polyethylene, polypropylene or another polymer. It is also conceivable that the substrate is formed by a liquid film, which is delimited, for example, by threads or wires. It is also conceivable to use the substrate only initially to support a deposition, so that after starting a deposition process, the thinnest layer that forms from then on itself forms the further substrate. It is also conceivable that the substrate contains seed structures for the deposition process.

It is also conceivable that the substrate is designed in the form of a wire or thread. In this case, it is conceivable that more than 2 rollers, for example 3 or 4 or 5 rollers, to arrange the wire-shaped substrate. In this case too, the rollers can be designed as cylinders, the base of which is oriented perpendicular to the substrate. Depending on the number of rollers, there are different options for applying electrical potential to one, several or all of the rollers. For example, a voltage source with more than two phases can be used and each role is assigned a phase of the voltage source. For example, three-phase three-phase current can be used and with three rolls around a wire-shaped substrate, a different phase can be connected to each roll, with the phases being offset from one another by 120°. There are numerous other options that can obviously be implemented by a person skilled in the art, not all of which need to be listed individually here.

It has also proven to be advantageous if the roller has elevations and/or notches. A surface of the peripheral side of the roller is therefore not smooth, but has mountain and/or valley-like structures. These, together with a rotation of the roller around the central axis arranged parallel to the substrate, help to transport reactive components of the plasma to the substrate, with the effect being similar to a paddle wheel.

It has proven to be advantageous if at least one gas inlet is arranged adjacent to the roller on a side opposite the substrate. A gas, which is required for a deposition on the substrate, can therefore be introduced next to the roller and can flow around it in order to be excited into a plasma in the vicinity of the roller and then hit the substrate in the form of a plasma.

Preferably, at least one gas outlet is arranged adjacent to the roller and adjacent to the substrate. This means that after the gas has passed through the substrate, it flows directly to the gas outlet. The gas inlet and gas outlet are arranged in such a way that, if possible, the gas is only directed to the substrate and can then be pumped out directly or led out of the system.

According to an advantageous development of the invention, there is at least one plane adjacent to the roller, which, at a distance from the roller, encloses the roller in a curved manner starting from the gas inlet to just before the substrate, forming a distance from the substrate. The plane can be made of sheet metal, for example. The plane thus acts like a flow baffle, which directs the gas from the gas inlet to the substrate and ensures that the gas can be excited into a plasma near the roller. So a flow channel is formed between the plane and the roller from the gas inlet to the substrate. The plane further prevents the plasma from expanding everywhere in the system and thus also serves to protect, for example, the housing of the system from plasma and excessive deposition of the thinnest layer - for example graphene - in places in the system where deposition is undesirable. Thus, the presence of the plane promotes concentrated layer formation on the substrate.

It has proven to be advantageous to design the level to be electrically grounded. Thus can A plasma can form cleanly, decoupled from a deposition site, ie without Ares. This avoids an electric arc through the plasma. The necessary gaseous, partially ionized molecules or ions can thus be generated in advance for the deposition, ie before the gas or plasma hits the substrate. The plasma thus remains stable within a defined area, i.e. in the flow channel delimited by the plane and the roller.

Preferably, a first substrate roll is arranged on a side opposite the gas inlet and the gas outlet, while a second substrate roll is arranged on a same side as the gas inlet and the gas outlet. The first substrate roll is designed to unroll the substrate and the second substrate roll is designed to roll up the substrate. Thus, the substrate can be conveyed taut by the first and second substrate rollers past the roller where the deposition takes place. For example, both the first substrate roll and the second substrate roll can be driven in rotation. Alternatively, the first substrate roll can also be mounted to rotate freely and only the second substrate roll is designed to be rotationally driven.

The system according to the invention, including its advantageous developments according to the dependent claims, is explained in more detail below using drawings.

• 1 schematisch eine erfindungsgemäße Anlage in einem Querschnitt;
• 2 schematisch zwei verschiedene Ausführungsformen für die Rolle.

It shows:

• 1 schematically a system according to the invention in a cross section;
• 2 schematically two different embodiments for the role.

In 1 A possible embodiment of system 1 is shown schematically in cross section. The system 1 has two roles 5. The substrate 4 is arranged centrally between the rollers 5 in such a way that the substrate 4 does not touch any of the rollers 5. The substrate 4 extends from the first substrate roll 8 to the second substrate roll 9, whereby the substrate 4 can be unrolled from the first substrate roll 8 and rolled onto the second substrate roll 9. The thinnest layer 2 is formed on the substrate 4.

Such an arrangement as in 1 is particularly advantageous for a band-shaped substrate 4. Alternatively, system 1 is also conceivable with only one role 5.

On the same side as the second substrate roll 9 there are - per roll - a gas inlet 6 and a gas outlet 7. The gas inlet 6 is arranged on the side of the roll 5 facing away from the substrate 4 and the gas outlet 7 is on the side of the substrate 4 facing side of the roller 5 arranged. The two gas outlets 7 are thus arranged adjacent to one another close to the substrate 4 or the second substrate roll 9.

Furthermore, the plane 10 can be seen, which, starting from the gas inlet 6, extends around the roller 5 following a curvature of the roller 5 until just before the substrate 4, forming a distance from the substrate 4. This forms a flow channel between the level 10 and the roller 5 from the gas inlet 6 to the substrate 4.

In the 1 The system 1 shown works as follows: The system 1 can be evacuated via the gas outlet or gas outlets 7, that is to say a pressure of, for example, 0.0001 to 100 mbar can be specifically set. Alternatively, a pressure of 100 to 2000 mbar can also be set. A gas can be introduced into the system 1 via the gas inlet or gas inlets 6. The gas may be a carbon-containing compound, such as methane, ethane, ethene, acetylene, propene, propane, benzene or another carbon compound. Furthermore, the gas can contain an inert component, such as a noble gas such as helium, neon, argon, xenon or krypton or another inert gas such as nitrogen. Furthermore, the gas can also contain a reducing component, such as hydrogen gas. Various possible compositions of these components for graphene vapor deposition are known in the art.

The introduced gas passes through at least one roller 5 and the flow channel formed by the roller 5 and the level 10. The roller 5 has a high electrical potential, whereby the gas forms a plasma. A first role 5 can be acted upon with cathodic potential and a second role 5 with anodic potential. Alternatively, the two can 1 The rollers 5 shown are also subjected to alternating voltage, the first roller 5 forming a counterpole to the second roller 5.

The roles 5 according to 1 have surveys 12 on their peripheral surfaces. By rotating the rollers 5 about their respective central axis 11, the elevations 12 are also rotated, so that the rollers 5 act similarly to paddle wheels and can transport the gas or plasma in the direction of the substrate 4. The rotation of the at least one roller 5 advantageously takes place in such a way that the roller 5 or the elevations 12 or depressions 13 on the roller 5 are rotated from the gas inlet 6 to the gas outlet 7. In the in 1 In the embodiment shown, this means that the rollers 5 rotate in opposite directions.

According to the invention, the at least one roller 5 serves both to generate the plasma and to transport the plasma to the substrate 4, in particular to a reaction zone between the plane 10 and the gas outlet 7. In an area of this reaction zone takes place adjacent to the at least one roller 5 the deposition of the thinnest layer 2 on the substrate 4 takes place, for example graphene. Since this deposition is supported by a plasma, this is a plasma-assisted chemical vapor deposition or plasma-enhanced physical vapor deposition, PE-CVD.

In 2 Two different embodiments for the roller 5, 5 'are shown schematically. The right-hand embodiment with elevations corresponds to the role 5 with elevations 12, as shown in 1 you can see. The left embodiment of the roller 5 'represents a cylinder in cross section which has notches 13. The notches 13 therefore correspond to recesses or dents on the peripheral side of the cylinder. Alternatively, rollers 5, 5' are also conceivable, which have both elevations and notches.

Reference symbol list

1

Attachment

2

thinnest layer

3

gas phase

4

Substrate

5

role

5'

role

6

Gas inlet

7

Gas outlet

8th

first substrate roll

9

second substrate roll

10

level

11

Central axis

12

surveys

13

Notches

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was 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

• WO 2020/187896 A1 [0003]
• EP 3632846 A1 [0004]

Claims (11)

Plant (1) for producing at least one thinnest layer (2), the thinnest layer (2) being formed from a gas phase (3) deposited on a substrate (4), characterized in that the substrate (4) is adjacent to at least a rotatably mounted roller (5) is arranged. Plant according to Claim 1 , characterized in that the roller (5) is designed to be acted upon with an electrical potential to form a plasma. Plant according to Claim 1 or 2 , characterized in that at least one gas inlet (6) is arranged adjacent to the roller (5) on a side opposite the substrate (4). System according to one of the preceding claims, characterized in that at least one gas outlet (7) is arranged adjacent to the roller (5) and adjacent to the substrate (4). Plant according to the Claims 3 and 4 , characterized in that a first substrate roll (8) is arranged on a side opposite the gas inlet (6) and the gas outlet (7). Plant according to the Claims 3 and 4 , characterized in that a second substrate roll (9) is arranged on a same side as the gas inlet (6) and the gas outlet (7). System according to one of the preceding claims, characterized in that the roller (5) has elevations (12) and/or notches (13). System according to one of the preceding claims, characterized in that the first substrate roll (8) is designed to unroll the substrate (4) and the second substrate roll (9) is designed to roll up the substrate (4). System according to one of the preceding claims, characterized in that adjacent to the roller (5) there is at least one plane (10) which, at a distance from the roller (5), curves the roller (5) starting from the gas inlet (6) until just before the substrate (4) encloses a distance from the substrate (4). Plant according to Claim 9 , characterized in that the plane (10) is designed to be electrically grounded. System according to one of the preceding claims, characterized in that at least two rollers (5) are provided, which are arranged such that the substrate (4) is positioned centrally between the rollers (5).

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