DE102020122679A1 - Process for depositing a two-dimensional layer - Google Patents

Abstract

The invention relates to a method for depositing a two-dimensional layer on a substrate (5) in a process chamber (6) of a CVD reactor (1) by feeding one or more reactive gases into the process chamber, the method comprising a plurality of process steps that follow one another in time, each characterized by a set of process parameters, which process parameters include at least a temperature, a total gas pressure in the process chamber (6), the type of reactive gas and a partial pressure of the reactive gas in the process chamber (6) or a mass flow of the reactive gas are in the process chamber (6), and the process steps (A, B, C) which follow one another in terms of time differ by a difference in at least one of the process parameters. In order to improve the layer quality of the deposited layer, the process parameters are selected such that in a first process step (A) spaced crystalline zones (10) are deposited on the surface of the substrate (5), in a second process step (A) following the first Process step (B) the number and/or the total area of the crystalline zones (10) is reduced and in a third process step (C) following the second process step (B) the areas of the crystalline zones (10) are increased.

Description

field of technology

The invention relates to a method for depositing a two-dimensional layer on a substrate in a process chamber of a CVD reactor by feeding one or more reactive gases into the process chamber, the method comprising a plurality of sequential process steps, each of which is characterized by a set of process parameters , which process parameters are at least a temperature, a total gas pressure in the process chamber, the type of reactive gas and a partial pressure of the reactive gas in the process chamber or a mass flow of the reactive gas into the process chamber, and the sequential process steps are different at least one of the process parameters differ.

State of the art

A method for depositing two-dimensional layers with two consecutive process steps is from U.S. 10,593,546 B2 famous. To deposit graphene layers on a substrate, which is arranged on a susceptor in a process chamber of a CVD reactor, a carrier gas and a reactive gas, for example CH ₄ , are fed into the process chamber through a gas inlet element. The two consecutive process steps are carried out with individual sets of process parameters. In a first process step, adsorbates are adsorbed on the surface. In the second process step, the adsorbates coalesce into a two-dimensional layer. Other methods for depositing two-dimensional layers disclose the US 9,394,599 B2 and U.S. 9,150,417 B2 .

Summary of the Invention

The object of the invention is to improve the process of the method described at the outset and/or to specify measures with which the layer quality of the deposited layer is improved.

The method according to the invention includes at least three steps that follow one another in time, with adsorbates being deposited on the surface of the substrate in the first step. In the process, crystalline zones form at a distance from one another. The crystalline zones are island-like areas in which a two-dimensional layer is formed from a two-dimensional material, with the process parameters in the first process step also being able to be selected in such a way that the island-like areas overlap. The island-like regions can have different shapes depending on the crystalline structure of the two-dimensional material. The shapes are typically geometric and exhibit symmetry, for example, they are triangular, square, rectangular, pentagonal, hexagonal, or polygonal. However, the island-like areas can also have no special structure. It is essential that the deposited material is inherently two-dimensional, i.e. consists of molecules that connect to one another on one level. In a second process step following the first process step, the number and/or the total area of the crystalline zones are reduced. The second process step can thus be an etching step. The essentially island-like crystalline zones deposited in the first process step are reduced in the second process step. The aim of the second process step is to reduce the areal density of the crystalline zones deposited during the first process step, which are nucleation zones. This is done on the one hand by etching the crystalline zones, ie by removing material. On the other hand, the process parameters in the second process step can also be chosen such that the crystalline zones formed during the first process step combine with one another, so that a first number of small crystalline zones becomes a second, smaller number of larger crystalline zones. This can be accompanied by a reduction in the total area of the crystalline zones. In a third process step following the second process step, the areas of the crystalline zones are enlarged. The aim of the third process step is to enlarge the crystalline zones without increasing the number of crystalline zones. The crystalline zones formed in the second process step should preferably become larger in the third process step until a completely closed layer has formed at the end of the third process step. In particular, it can be provided that in the first process step, which can last from one to 10 minutes, a surface density of the crystalline zones as nucleation zones is set that is greater than one nucleation zone per square micrometer. However, the areal density can also be more than 10 nuclei per square micron, more than 100 nuclei per square micron, or more than 1000 nuclei per square micron. In the second process step, this areal density can decrease to less than 0.01 crystalline zone per square micron, 0.1 crystalline zone per square micron, or less than one crystalline zone per square micron. During the second process step, the areal density can be reduced by a factor of at least 2, 5, 10, 20, 50, 100, 500 or 1000. A substrate temperature or a susceptor temperature can be selected end of the second process step must be greater than in the first process step. The substrate temperature or susceptor temperature can be higher during the third process step than during the second process step. When depositing WS ₂ using a tungsten-containing reactive gas and a sulfur-containing reactive gas, for example W(CO) ₆ , S(C ₄ H ₉ ) ₂ [DTBS] or S(CH ₃ ) ₂ [DMS], S (C ₂ H ₅ ) ₂ [DES] or H2S, the temperature of the first process step can range between 400°C and 800°C. During the second process step the temperature can range between 600°C and 1000°C and in the third process step between 700°C and 1000°C. When depositing graphene using CH ₄ , the temperature in the first process step can be between 1200°C and 1400°C. In the second process step, the temperature can range between 1200°C and 1600°C. In the third process step, the temperature can be in the range of 1400°C and 1600°C. While the deposition of WS ₂ takes place at total pressures in the range between 50 and 400 mbar, the deposition of graphene takes place at total pressures in the range from 50 to 900 mbar. When depositing WS ₂ , a bubbler can be used through which a carrier gas flows, which can contain nitrogen, argon, but also hydrogen. The substance stored in the bubbler is transported as a gas with the carrier gas. In the first process step, the carrier gas flow is about 0.1% to 10% of the total gas flow. The molar ratio between sulfur and tungsten can range between 50 to 55,000. When depositing graphene, the CH ₄ fraction of the total flux can range from 0.03% to 0.5%. If hydrogen is fed in in addition to CH ₄ , the H ₂ /CH ₄ ratio can be in the range between 1% and 90%. In the second process step, preferably only hydrogen can be fed into the process chamber, since hydrogen develops a corrosive effect. When hydrogen is fed in, the size of the total area of the crystalline zones deposited in the first process step is reduced. The second process step can be shorter than 10 minutes. In the second process step, hydrogen can be fed in as a component of a carrier gas, which can contain nitrogen or argon, with a proportion of between 0 and 100% of the total carrier gas flow. The process parameters in the third process step can essentially only differ from the other process steps in terms of the process temperature, with the duration of the third process step preferably being longer than 10 minutes. In particular, it is provided that the duration of the first process step is longer than the duration of the second process step, that the duration of the third process step is longer than the duration of the second process step and that the duration of the third process step is longer than the duration of the first process step . The first process step is preferably a nucleation step, the second process step is an etching step and the third process step is a growth step. In a development of the method, it is proposed that the process parameters also include a distance between a gas outlet surface of a gas inlet element and the substrate, with this distance being smaller in the first process step than in the third process step. The distance between the substrate or susceptor and the gas outlet surface of the gas inlet element can be in the range between 9 mm and 15 mm in the first process step and in a range between 15 mm and 25 mm in the third process step. Provision can furthermore be made for the first process step to be preceded by a preparatory process step in which the substrate is heated to a temperature in the range between 800° C. and 1400° C.

character list

• 1 schematisch einen CVD-Reaktor 1,
• 2 schematisch einen Temperaturverlauf während der drei Prozessschritte A, B, C,
• 3 schematisch den Gasfluss Q des reaktiven Gases in den drei Prozessschritten A, B, C,
• 4 schematisch den Gasfluss von H2 in den drei Prozessschritten A, B, C,
• 5a schematisch einen Schnitt durch ein Substrat 5 vor Beginn des ersten Prozessschrittes A,
• 5b schematisch das Substrat 5 während des ersten Prozessschrittes A,
• 5c schematisch das Substrat 5 beim Ende des ersten Prozessschrittes A,
• 5d schematisch das Substrat 5 beim Ende des zweiten Prozessschrittes B,
• 5e schematisch das Substrat 5 während des dritten Prozessschrittes C und
• 5f schematisch das Substrat 5 beim Ende des dritten Prozessschrittes C.

An embodiment of the invention is explained below with reference to the accompanying drawings. Show it:

• 1 schematically a CVD reactor 1,
• 2 a schematic of a temperature curve during the three process steps A, B, C,
• 3 schematically the gas flow Q of the reactive gas in the three process steps A, B, C,
• 4 schematically the gas flow of H2 in the three process steps A, B, C,
• 5a schematically a section through a substrate 5 before the start of the first process step A,
• 5b schematically the substrate 5 during the first process step A,
• 5c schematically the substrate 5 at the end of the first process step A,
• 5d schematically the substrate 5 at the end of the second process step B,
• 5e schematically the substrate 5 during the third process step C and
• 5f schematically the substrate 5 at the end of the third process step C.

Description of the embodiments

the 1 shows schematically a CVD reactor 1, which is suitable for carrying out the method according to the invention. In the housing of the CVD reactor 1, which can be made of stainless steel and is stable enough that the housing cavity can be evacuated, there is a Gas inlet element 2. The gas inlet element 2 is a hollow body which can be supplied with a reactive gas from outside the housing 1. The reactive gas is fed into the gas inlet element 2 through a feed line together with a carrier gas, which can be hydrogen, nitrogen and argon. As a reactive gas, CH ₄ can be used to deposit graphene and tungsten/sulfur compounds to deposit WS ₂ . However, other gases, for example gases containing molybdenum, can also be used in order to deposit layers with different layer compositions. According to the invention, the reactive gas, which can consist of one or more components, is chosen such that a two-dimensional layer is formed on a substrate 5 within a process chamber 6 . The gas inlet element 2 has a flat gas outlet surface 3 facing the process chamber 6 through which the gas fed into the gas inlet element can enter the process chamber 6 . The upper side of a susceptor 4, which can be made of graphite or another temperature-resistant material, extends parallel to the gas outlet surface 3. A heating device 7 is located below the susceptor 4 in order to bring the susceptor 4 to a process temperature. The process temperature can be measured using optical or other suitable measuring instruments on the surface of the substrate or in the gas phase in the process chamber 6 . However, the process temperature can also be measured on the rear side of the susceptor 4 pointing towards the heating device 7 . The susceptor 4 preferably carries crystalline substrates 5 on its surface facing the process chamber 6. Sapphire substrates, silicon substrates, graphite substrates or the like can be used as substrates. SiC substrates or the like can be used, these or other substrates can also have a layer of SiO ₂ , SiC, graphene or the like. In the gas outlet surface 3 there are gas outlet openings distributed essentially uniformly over the entire surface, which give the gas inlet element the appearance of a shower head. Two feed lines 8 ′, 9 can open into the gas inlet element 2 . The reactive gas can be fed into the gas inlet element 2 through a first feed line 8 ′, and a carrier gas or an inert gas can be fed into the gas inlet element 2 through a second feed line 9 . In a first variant, W(CO) ₆ from a bubbler 8 can be fed into the gas inlet element 2 through a first supply line 8'. For this purpose, the carrier gas or the inert gas is introduced into the bubbler 8 . While nitrogen or argon act as true inert gases, hydrogen can influence the growth rate of the two-dimensional layer or even have an etching effect. A second bubbler, not shown, can contain S(C ₄ H ₉ ) ₂ . With a carrier gas, S(C ₄ H ₉ ) ₂ can be fed into the process chamber through a second feed line. In a second variant, CH ₄ is fed into the process chamber instead of W(CO) ₆ . Here, too, the addition of hydrogen can have an effect on the growth rate of the two-dimensional layer, or even an etching effect. Other etching gases can also be used in the second step, for example O ₂ , O ₃ , Cl ₂ , F ₂ or other halides. Etching gases cannot consist of just one element. It is also provided that etching gases consist not only of one element but of chemical compounds, for example the following substances come into consideration: NH ₃ , HCl, CO ₂ , CO, H ₂ O ₂ , N ₂ O, SOCl ₂ . It is further envisaged that hydrides, halocarbons, reducing or oxidizing substances can be used as etchants.

With the method according to the invention, connected two-dimensional monolayers are deposited on preferably crystalline substrates, a CVD method, preferably an MOCVD method, being used. The method of the present invention can be used to deposit continuous layers of one element at a time, with the atoms forming the layer arranged in a two-dimensional array. In particular, graphene, silicene, germanes, borophene or phosphorene can be deposited. In addition, the method according to the invention can also be used to deposit coherent layers each consisting of a plurality of elements, with the atoms or molecules forming the layers being arranged in a two-dimensional arrangement. In particular, it is envisaged that elements of III. and V. main group, for example hexagonal boron nitride or elements of VI. Main group, e.g. oxides are deposited. Provision can also be made for transition metal dichalcogenides to be deposited, for example MXenes, for example metal sulfides, selenides or tellurides. Three process steps A, B, C are carried out one after the other, with the process steps A, B, C differing from one another by at least one process parameter. The following process parameters can be considered: The temperature, which can be a substrate temperature, a susceptor temperature or a gas temperature in the process chamber 5, the total pressure in the process chamber 5, the partial pressure of the reactive gas or the partial pressures of various reactive gases that simultaneously fed into the process chamber 5, the mass flow of the reactive gas or the mass flow of the carrier gas, the ratio of the flows of the reactive gas and the carrier gas to one another, the duration of the process steps A, B, C and/or the distance d from the susceptor 4 to the gas outlet surface 3.

The three process steps A, B, C are carried out at temperatures T1, T2, T3 and gas flows into the process chamber 6 that are typical for them. These process parameters are selected in such a way that adsorbates 11 are deposited on the surface 5 of the substrate during the first process step, which is a nucleation step. The adsorbates are molecules of the reactive gases or reaction products of the reactive gases or molecular assemblies of the reaction products. The substrate uncoated before the first process step A ( 5a) is heated to a temperature which is between 400°C and 800°C when depositing WS2 and between 1200°C and 1400°C when depositing graphene. One or more reactive gases, for example W(CO) ₆ , S(C ₄ H ₉ ) ₂ [DTBS] or S(CH ₃ ) ₂ [DMS], S(C ₂ H ₅ ) ₂ [DES], are injected into the process chamber. , H ₂ S etc. are fed in. Initially, individual island-shaped adsorbates 11 are formed (see Fig 5b) . The area of the substrate that is covered with the adsorbates 11 increases during the first process step A, with individual larger crystalline zones 10 being formed at a distance from one another. The temperature of the susceptor 4 is high enough for the gaseous starting materials to decompose and nuclei or crystalline zones 10 to form. To modulate the growth rate, hydrogen can also be fed into the process chamber during the first process step A, which hydrogen can have a corrosive effect.

In the second process step B, the temperature is raised, for the growth of WS ₂ to a temperature T ₂ in the range between 600°C and 1000°C, for the growth of graphene in the range between 1200°C and 1600°C. The second process step B is preferably carried out without a flow of the reactive starting material, ie for example W(CO) ₆ etc. or CH ₄ into the process chamber. The process parameters in the second process step B are set in such a way that the total area of the crystalline zones 10 or the number of the crystalline zones 10 is reduced. Provision can be made for feeding into the process chamber during the second process step H2. This is preferably done with an inert gas, which can be N ₂ or Ar. During the second process step B, the density of the two-dimensional crystals deposited during the first process step on the surface of the substrate 5 decreases. The second process step B is therefore a annealing or etching step. the 5d shows schematically the substrate at the end of the second process step. The number of crystalline zones 10 may have increased or decreased. However, the total area of the crystalline zones 10 has decreased. Some of the crystalline zones 10 formed during the first process step A have connected to other crystalline zones 10 .

In the third process step C, the temperature is increased further, for example to a temperature in the range between 700° C. and 1000° C. when depositing WS ₂ or to a temperature in the range from 1400° C. to 1600° C. when depositing graphene. During the third process step C, the reactive starting material, ie for example W(CO) ₆ plus the above-mentioned sulphur-containing compounds or CH ₄ is fed into the process chamber. The H ₂ flow into the process chamber is reduced or completely suppressed, so that during the third process step C the surface coverage of the substrate with deposited crystals increases. The H2 flow is preferably adjusted in such a way or the ratio between the H ₂ flow and the reactive gas flow is adjusted in such a way that no new crystalline zones 10 form during the third process step C, but only the crystalline zones 10 formed in the second process step B enlarge (see 5e) until a completely closed two-dimensional layer is reached (see 5e) .

the 2 until 4 show the temperature T ( 2 ), the total flow Q of the reactive starting material ( 3 ) and the total flux of hydrogen ( 4 ) into the process chamber. It can be seen that in the first process step A for the duration of a time t ₁ a larger mass flow of the reactive gas is fed into the process chamber than in the third process step C. In the second process step B, however, no reactive gas is fed into the process chamber, but instead a greater mass flow of H ₂ than in the first process step A or in the third process step C. The 2 shows that the temperatures gradually increase during the three consecutive process steps A, B, C.

During the first process step, the distance d between the gas outlet surface 3 and the susceptor 4 can be 5 to 15 mm. During the third process step C, the distance d can be in the range between 15 mm and 25 mm.

The above explanations serve to explain the inventions covered by the application as a whole, which also independently develop the state of the art at least through the following combinations of features, whereby two, several or all of these combinations of features can also be combined, namely:

A method, which is characterized in that the process parameters are chosen so that in a first process step A on the surface of the substrate 5 spaced apart kristal line zones 10 are deposited, in a second process step B following the first process step B the number and/or the total area of the crystalline zones 10 is reduced and in a third process step C following the second process step B the areas of the crystalline zones 10 are increased.

A method which is characterized in that in the second process step B several crystalline zones 10 connect to each other and/or that the areal density of the crystalline zones 10 during the second process step B from initially more than one crystalline zone 10 per square micron, more than ten crystalline zones 10 per square micron, more than one hundred crystalline zones 10) per square micron, or more than one thousand crystalline zones 10 per square micron down to less than 0.001 crystalline zones 10 per square micron, less than 0.1 crystalline zones 10 per square micron, or less than 1 crystalline zone 10 per square micrometer and/or that the areal density of the crystalline zones 10 is reduced by at least a factor of 2, 5, 10, 20, 50 or 100 or 1000 during the second process step.

A method which is characterized in that the process parameters in the third process step C are selected in such a way that no new crystalline zones 10 are formed there, but only existing crystalline zones 10 grow together.

A method which is characterized in that the partial pressure of the reactive gas or the mass flow of the reactive gas in the third process step C is lower than in the first process step A and/or that the time duration of the first process step A is longer than the time duration of the second process step B and/or that the duration of the third process step C is longer than the duration of the second process step B and/or that the duration of the third process step C is longer than the duration of the first process step A.

A method characterized in that the deposited two-dimensional material consists of a chemical element and/or is graphene, silicene, germanen, borophene or phosphorene and/or that the deposited two-dimensional material consists of chemical compounds and/or a III-V compound and/or hexagonal boron nitride and/or a II-VI compound and/or a metal oxide and/or a transition metal dichalcogenide and/or MXenes and/or a metal sulfide, a metal selenide or a metal telluride.

A method which is characterized in that the temperature T ₁ in the first process step A is lower than in the second process step B and/or that the temperature T ₂ in the second process step B is lower than in the third process step C and/or that when used of W(CO) ₆ , DTBS, DMS, DES or H2S as the reactive gas, the temperature T ₁ in the first process step A is in the range between 400 to 800°C and/or the temperature T ₂ in the second process step B is in the range between 600 to 1000° C. and/or the temperature T ₃ in the third process step C is in the range between 700 and 1000° C. or that when CH ₄ is used as the reactive gas the temperature T ₁ in the first process step A is in the range between 1200 and 1400° C and/or the temperature T ₂ in the second process step B is in the range between 1200 and 1600°C and/ or the temperature T ₃ in the third process step C is in the range between 1400 and 1600°C.

A process characterized in that the total pressure when using W(CO), DTBS, DMS, DES or H ₂ S ₆ is in the range between 50 and 400 mbar and when using CH ₄ in the range between 50 and 900 mbar.

A method which is characterized in that in the second process step B essentially exclusively a carrier gas or a mixture of an inert gas and hydrogen is fed into the process chamber and/or that in the first and in the third process step C a carrier gas is fed into the process chamber together with the reactive gas Process chamber is fed and / or that a fed in the process steps carrier gas contains hydrogen.

A method which is characterized in that the process parameters also include a distance d between a gas outlet surface 3 of a gas inlet element 2 and the substrate 5 and this distance d is smaller in the first process step A than in the third process step C and/or that the distance d between a gas outlet surface 3 of a gas inlet element 2 to the substrate in the first process step A is in the range between 5 and 15 mm and in the third process step C in a range between 15 and 25 mm.

A method characterized in that the first process step A is preceded by a preparatory process step in which the substrate 5 is heated to a temperature in the range between 800 to 1400°C.

A method characterized in that during the second process step BH ₂ , O ₂ , O ₃ , Cl ₂ , F ₂ or another halide or NH ₃ , HCl, CO ₂ , CO, H ₂ O ₂ , N ₂ O or SOCl ₂ or another hydride or halocarbon or a reducing or oxidizing substance is fed into the process chamber.

A method which is characterized in that a plurality of two-dimensional layers are deposited one on top of the other, the layers consisting of the same or different materials and/or wherein in repetitive process steps A, B, C layers according to one of claims 1 to 11 are each applied to one previously deposited layer are deposited and / or wherein starting materials are changed between the steps.

All disclosed features are essential to the invention (by themselves, but also in combination with one another). The disclosure of the application also includes the disclosure content of the associated/attached priority documents (copy of the previous application) in full, also for the purpose of including features of these documents in claims of the present application. The subclaims, even without the features of a referenced claim, characterize with their features independent inventive developments of the prior art, in particular for making divisional applications on the basis of these claims. The invention specified in each claim can additionally have one or more of the features specified in the above description, in particular with reference numbers and/or specified in the list of reference numbers. The invention also relates to designs in which some of the features mentioned in the above description are not implemented, in particular if they are clearly unnecessary for the respective application or can be replaced by other technically equivalent means.

Reference List

1

CVD reactor, housing

2

gas inlet element

3

gas exit surface

4

susceptor

5

substrate

6

process chamber

7

heating

8th

bubblers

8th'

supply line

9

supply line

10

crystalline zone

11

adsorbate

12

adsorbate

i.e

distance

t1

Time

t2

Time

t3

Time

A

first process step, nucleation step

B

second process step, intermediate step, etching step

C

third process step, coalescence step, growth step

T1

first temperature

T2

second temperature

T3

third temperature

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited 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.

Patent Literature Cited

• US10593546B2 [0002]
• US9394599B2 [0002]
• US9150417B2 [0002]

Claims (13)

Method for depositing a two-dimensional layer on a substrate (5) in a process chamber (6) of a CVD reactor (1) by feeding one or more reactive gases into the process chamber, the method comprising a plurality of process steps that follow one another in terms of time, each of which is Set of process parameters are characterized, which process parameters at least a temperature, a total gas pressure in the process chamber (6), the type of reactive gas and a partial pressure of the reactive gas in the process chamber (6) or a mass flow of the reactive gas in the process chamber ( 6) and the sequential process steps (A, B, C) differ in that at least one of the process parameters differs, characterized in that the process parameters are selected such that in a first process step (A) on the surface of the substrate (5) spaced apart crystalline zones (10) are deposited in one the second process step (B) following the first process step (A) the number and/or the total area of the crystalline zones (10) is reduced and in a third process step (C) following the second process step (B) the areas of the crystalline zones (10 ) can be enlarged. procedure after claim 1 , characterized in that in the second process step (B) several crystalline zones (10) connect to one another and/or that the areal density of the crystalline zones (10) during the second process step (B) from the beginning more than one crystalline zone ( 10) per square micron, greater than ten crystalline zones (10) per square micron, greater than one hundred crystalline zones (10) per square micron, or greater than one thousand crystalline zones (10) per square micron down to less than 0.001 crystalline zones (10) per square micron, less than 0.1 crystalline zone (10) per square micrometer or less than 1 crystalline zone (10) per square micrometer and/or that the areal density of the crystalline zones (10) during the second process step changes by at least a factor of 2, 5, 10, 20, 50 or 100 or 1000 diminished. Method according to one of the preceding claims, characterized in that the process parameters in the third process step (C) are selected in such a way that no new crystalline zones (10) are formed there, but only existing crystalline zones (10) grow together. Method according to one of the preceding claims, characterized in that the partial pressure of the reactive gas or the mass flow of the reactive gas in the third process step (C) is lower than in the first process step (A) and/or that the duration of the first process step (A) is longer than the duration of the second process step (B) and/or that the duration of the third process step (C) is longer than the duration of the second process step (B) and/or that the duration of the third process step (C) is longer is than the duration of the first process step (A). Method according to one of the preceding claims, characterized in that the deposited two-dimensional material consists of a chemical element and / or graphene, silicene, germanes, borophene or phosphorus and / or that the deposited two-dimensional material consists of chemical compounds and / or a III -V compound and/or hexagonal boron nitride and/or a II-VI compound and/or a metal oxide and/or a transition metal dichalcogenide and/or MXenes and/or a metal sulfide, a metal selenide or a metal telluride. Method according to one of the preceding claims, characterized in that the temperature (T ₁ ) in the first process step (A) is lower than in the second process step (B) and/or that the temperature (T ₂ ) in the second process step (B) is lower than in the third process step (C) and/or that when using W(CO) ₆ , S(C ₄ H ₉ ) ₂ [DTBS], S(CH ₃ ) ₂ [DMS], S(C ₂ H ₅ ) ₂ [DES] or H ₂ S as a reactive gas, the temperature (T ₁ ) in the first process step (A) is in the range between 400 and 800 ° C and / or the temperature (T ₂ ) in the second process step (B) in the range between 600 to 1000 ° C and / or the temperature (T ₃ ) in the third process step (C) in the range between 700 to 1000 ° C or that when using CH ₄ as a reactive gas, the temperature (T ₁ ) in the first process step (A) in the range between 1200 to 1400°C and/or the temperature (T ₂ ) in the second process step (B) in the range between 1200 to 1600°C and/or the temperature (T ₃ ) in the third process step (C) is in the range between 1400 to 1600°C. Method according to one of the preceding claims, characterized in that the total pressure when using W(CO), S(C ₄ H ₉ ) ₂ [DTBS], S(CH ₃ ) ₂ [DMS], S(C ₂ H ₅ ) ₂ [DES] or H ₂ S ₆ in the range between 50 and 400 mbar and when using CH ₄ in the range between 50 and 900 mbar. Method according to one of the preceding claims, characterized in that in the second process step (B) essentially exclusively a carrier gas or a Mixture of an inert gas and hydrogen is fed into the process chamber and/or that in the first and in the third process step (C) a carrier gas is fed into the process chamber together with the reactive gas and/or that a carrier gas fed in during the process steps contains hydrogen. Method according to one of the preceding claims, characterized in that the process parameters also include a distance (d) between a gas outlet surface (3) of a gas inlet element (2) and the substrate (5) and this distance (d) in the first process step (A) is less than in the third process step (C) and/or that the distance (d) between a gas outlet surface (3) of a gas inlet element (2) to the substrate in the first process step (A) is in the range between 9 and 15 mm and in the third process step (C) in one range between 15 and 25 mm. Method according to one of the preceding claims, characterized in that the first process step (A) is preceded by a preparatory process step in which the substrate (5) is heated to a temperature in the range between 800 and 1400°C. Method according to one of the preceding claims, characterized in that during the second process step (B) H ₂ , O ₂ , O ₃ , Cl ₂ , F ₂ or another halide or NH ₃ , HCl, CO ₂ , CO, H ₂ O ₂ , N ₂ O or SOCl ₂ or another hydride or halocarbon or a reducing or oxidizing substance is fed into the process chamber. Method according to one of the preceding claims, characterized in that a plurality of two-dimensional layers are deposited one on top of the other, the layers consisting of the same or different materials and / or wherein in repetitive process steps (A, B, C) layers according to one of Claims 1 until 11 are each deposited on a previously deposited layer and/or wherein starting materials are changed between the steps. Method, characterized by one or more of the characterizing features of one of the preceding claims.

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