Method for pyrolyzing graphene by etching SiC surface with metal Ag nanoparticles and application

Abstract

The invention relates to a method for pyrolyzing graphene by etching a SiC surface through metal Ag nanoparticles and application, and belongs to the technical field of two-dimensional material patterning. According to the method, SiC pyrolytic graphene with a metal nano Ag film growing on the surface is placed in a closed confined container, vacuum high-temperature annealing is carried out, and metal Ag nano particles can etch a graphene layer in the volatilization process. The confinement type annealing etching technology is simple and effective, has no requirement on the surface polarity of the SiC substrate, is expected to promote large-scale uniform patterning preparation of SiC pyrolytic graphene, and provides guidance and reference values for practical application of a two-dimensional material in the field of microelectronics.

Description

Technical Field

[0001] The present invention belongs to the technical field of two-dimensional material patterning, and specifically is a method and application of etching SiC surface pyrolyzing graphene by using metal Ag nanoparticles. Background Art

[0002] According to Moore's Law, the channel size of traditional silicon-based transistors has reached the physical limit of less than 5 nm. Therefore, the development of integrated circuits has faced technical bottlenecks in manufacturing. From the perspective of new material research and development, it is urgent to seek new alternatives to single-crystalline silicon materials for the development and application of future microelectronic devices. SiC pyrolytic graphene is produced by high-temperature pyrolysis of a single-crystalline SiC matrix and has excellent electron mobility, thermal conductivity, etc. Due to the semiconductor properties of the SiC matrix, SiC pyrolytic graphene can be directly applied to electronic devices without transfer, and its manufacturing process is integrated with traditional silicon-based processes. SiC pyrolytic graphene is expected to become an ideal candidate semiconductor material for the silicon-based post-Moore era, and has shown broad application prospects in the field of microelectronics. Since its discovery, SiC pyrolytic graphene has attracted much attention. The collaborative research between Professor Ma Lei's team at Tianjin University and Professor Walter A. de Heer's team at Georgia Institute of Technology has made a major breakthrough. Based on the quasi-equilibrium annealing technology, a regular and ordered single-layer graphene can be prepared on the SiC surface, creating the world's first functional SiC-based graphene semiconductor, thus opening up the practical application of SiC pyrolytic graphene in the semiconductor field.

[0003] The nanoscale width of graphene strips can regulate its surface electron migration characteristics and open its energy band gap, laying the foundation for the application of high-performance electronic devices. In the past decade, the patterning research on SiC pyrolytic graphene surface has been relatively active and has become a striking research branch. Scientists have provided a variety of strategies for graphene structure regulation and patterning, and various graphene etching methods have been born. Catalytic cutting of metal nanoparticles is a very promising technical method. Metal nanoparticles "bite off" edge carbon atoms through the synergistic action of multiple metal atoms, and use the "Pac-Man" cutting mechanism to create smooth-edged and orderly arranged graphene nanostructures. According to the size effect of metal nanoparticles, the reaction rates of different types of edge sites are different, and the overall carbon atom etching rate is linearly dependent on the surface area of ​​the nanoparticles. The exploration of these mechanisms has opened up new ways to improve the controllability of graphene cutting. However, the patterning of SiC pyrolytic graphene has always been difficult. It is difficult to uniformly and effectively regulate the graphene pattern on the SiC surface, and related exploration is worth in-depth. Summary of the invention

[0004] The purpose of the present invention is to address the problems existing in the above-mentioned prior art, combine the catalytic cutting mechanism of metal nanoparticles, and provide a method for etching pyrolytic graphene on the surface of SiC using metal Ag nanoparticles, thereby solving the problem of large-scale uniform etching of pyrolytic graphene on SiC in the prior art.

[0005] The present invention is achieved through the following technical solutions: A method for pyrolyzing graphene on a SiC surface by etching with metal Ag nanoparticles comprises the following steps: S1: heat-treating a single crystal SiC substrate to obtain SiC pyrolytic graphene.

[0006] S2: grow a layer of metal nano-Ag film on the surface of SiC pyrolysis graphene.

[0007] S3: placing the SiC pyrolytic graphene with a metal nano-Ag film grown on the surface upside down in a confined annealing container for vacuum high-temperature annealing treatment to achieve etching of the SiC pyrolytic graphene surface by the metal Ag nanoparticles.

[0008] The method of the present invention is based on the "eating beans" mechanism of metal Ag atoms during annealing, crystallization and volatilization, and can simply and quickly achieve uniform etching of pyrolytic graphene on the SiC surface. The inverted placement of the sample can construct a confined space in a limited space, and the rapid volatilization of metal Ag atoms can be suppressed under heating annealing conditions, increasing the probability of interaction between metal Ag atoms and C atoms.

[0009] As a preferred technical solution, in step S1, the single crystal SiC substrate is pretreated before heat treatment, and the pretreatment is to heat the single crystal SiC substrate to 600-700°C under vacuum conditions and keep the temperature for 8 hours.

[0010] As a preferred technical solution, in step S1, the heat treatment temperature is 1300-1400°C, and the heat treatment time is 10-20 min, so that a thin layer of graphene can be grown on the surface of the SiC substrate.

[0011] As a preferred technical solution, in step S2, a metal nano-Ag film is grown on the surface of SiC pyrolytic graphene using molecular beam epitaxial growth technology. During the molecular beam epitaxial growth process, the heating temperature of the metal Ag source material is 700-900°C and the growth time is 10-20 min.

[0012] As a preferred technical solution, in step S3, when the SiC pyrolytic graphene with a metal nano-Ag film grown on the surface is placed upside down, a small gap is set on the contact surface.

[0013] As a preferred technical solution, in step S3, during the vacuum high temperature annealing treatment, the vacuum degree range is 1×10 -1 – 5×10 -1 Torr; the heating rate is 20-30 ℃ / min, and the sum of the heating time and the holding time does not exceed 1h; the annealing temperature is 800-900 ℃, and the annealing time is 30-60 min, which can allow the metal Ag particles to etch the SiC pyrolytic graphene.

[0014] As a preferred technical solution, in step S2, the thickness of the grown metal nano-Ag film is 10-20 nm, which can make the surface of SiC pyrolytic graphene uniformly covered with Ag atoms.

[0015] Furthermore, the present invention also provides a SiC pyrolytic graphene whose surface is etched by metal Ag nanoparticles, and the graphene pattern is prepared by the above-mentioned method of etching SiC surface pyrolytic graphene by metal Ag nanoparticles.

[0016] Furthermore, the present invention also provides the use of the SiC pyrolytic graphene whose surface is etched by metal Ag nanoparticles in integrated circuits.

[0017] In summary, the method of the present invention is to place SiC pyrolytic graphene with a metal nano-Ag film on the surface in a closed confined container, and after vacuum high-temperature annealing, the metal Ag nanoparticles can etch the graphene layer during the volatilization process. The confined annealing and etching technology of the present invention is simple and effective, has no requirements for the surface polarity of SiC, and is expected to promote the large-scale uniform patterning preparation of SiC-based graphene, providing guidance and reference value for the practical application of two-dimensional materials in the field of microelectronics. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments of the present invention are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 It is a schematic diagram of the metal Ag atom confined annealing process technology in Example 1 of the present invention.

[0020] Figure 2 It is a schematic diagram of the principle of etching the surface of SiC pyrolytic graphene by metal Ag atoms in the method of the present invention.

[0021] Figure 3This is the SEM characterization result of the surface morphology of SiC pyrolytic graphene after metal Ag atom etching in Example 2 of the present invention.

[0022] Figure 4 This is the Raman characterization result of SiC pyrolyzed graphene after metal Ag atom etching in Example 3 of the present invention. DETAILED DESCRIPTION

[0023] The embodiments of the technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and the protection scope of the present invention cannot be limited thereto. It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should be the common meanings understood by those skilled in the art to which the present invention belongs.

[0024] The present invention provides a method for etching pyrolytic graphene on the surface of SiC using metal Ag nanoparticles. The method mainly realizes large-scale and uniform etching of pyrolytic graphene on SiC by a confined volatilization process of metal Ag atoms, and specifically comprises the following steps: S1: Pre-treat the single crystal SiC substrate first, then perform a high temperature annealing heat treatment, and finally obtain SiC pyrolytic graphene.

[0025] In this step, the SiC substrate is a grade A sample, and both the Si surface and the C surface are acceptable, and single-side polishing is performed.

[0026] The pretreatment process is as follows: the clean single crystal SiC substrate is introduced into the vacuum chamber, and the single crystal SiC substrate is heated and degassed by direct current under vacuum conditions to remove impurities such as water vapor and adsorbed substances on its surface. The direct current used for pretreatment is 0.5-0.7 A, the heating temperature is 600-700 °C, and the degassing holding time is 8 h. In this step, the background vacuum value of the sample preparation chamber is less than 5×10 -9 Torr.

[0027] The heat treatment process of high temperature annealing is: using direct current to heat the single crystal SiC substrate, the direct current is 2.0-2.5 A, the heat treatment temperature is 1300-1400°C, and the heating time is 10-20 min.

[0028] S2: grow a layer of metal nano-Ag film on the surface of SiC pyrolysis graphene.

[0029] The specific process is as follows: a layer of metal nano-Ag film is grown on the surface of SiC pyrolytic graphene using molecular beam epitaxial growth technology; during the molecular beam epitaxial growth process, a K-Cell evaporation source is used to heat the metal Ag source material to 700-900°C through a direct current of 1.9-2.3 A and a growth time of 10-20 min; the thickness of the finally grown metal nano-Ag film is 10-20 nm.

[0030] S3: The SiC pyrolytic graphene with a metal nano-Ag film grown on the surface is placed upside down in a confined annealing container for vacuum high-temperature annealing to achieve etching of the surface of the SiC pyrolytic graphene by the metal Ag nanoparticles, such as Figure 1 and Figure 2 As shown; when the SiC pyrolytic graphene with a metal nano-Ag film grown on the surface is placed upside down, a small gap is set between the contact surface of the metal nano-Ag film and the bottom of the container, forming only a tiny gap.

[0031] The vacuum high temperature annealing process is as follows: the vacuum range of the confined annealing container is 1×10 -1 – 5×10 -1 Torr; the heating rate is 20 – 30 ℃ / min, and the sum of the heating time and the holding time does not exceed 1h; the annealing temperature is 800 – 900 ℃, and the annealing time is 30 – 60 min.

[0032] The present invention utilizes the confined etching technology of confined metal Ag atoms to simply and quickly achieve large-area uniform etching of SiC pyrolytic graphene. The sample inverted placement method can construct a confined space in a limited space, which can inhibit the rapid volatilization of metal Ag atoms under heating annealing conditions and increase the probability of interaction between metal Ag atoms and C atoms. The etching technology of the present invention is simple and effective, and can be extended to the surface etching of various types of SiC pyrolytic graphene, providing guidance and reference for promoting the practical application of SiC pyrolytic graphene in the fields of microelectronics and the like.

[0033] Combined with the etching principle and the accompanying drawings, the etching technology in the method of the present invention is described in detail: Etching principle: Figure 1 As shown in the figure, the SiC pyrolytic graphene with a metal nano-Ag film grown on the surface is placed upside down in a confined annealing container. This method can construct a confined space in a limited space, which can effectively suppress the volatilization rate of the metal Ag atoms under heating annealing conditions and increase the probability of mutual rental of metal Ag atoms and C atoms; the pre-deposited metal Ag atoms recrystallize into larger particles during the high-temperature annealing process, and volatilize under continuous annealing conditions, forming an etch on the surface of the SiC pyrolytic graphene, as shown in the figure. Figure 2 shown.

[0034] Furthermore, the present invention also provides a SiC pyrolytic graphene whose surface is etched by metal Ag nanoparticles, and the graphene pattern is prepared by the above-mentioned method of etching SiC surface pyrolytic graphene by metal Ag nanoparticles.

[0035] Furthermore, the present invention also provides the use of the SiC pyrolytic graphene whose surface is etched by metal Ag nanoparticles in integrated circuits.

[0036] The technical solution of the present invention mainly utilizes the confined intercalation technology to realize large-scale uniform intercalation of metal Ag atoms in SiC pyrolytic graphene. The following lists several specific preparation method implementation cases to further illustrate the technical solution of the present invention: Example 1

[0037] The Si-terminated single crystal 6H-SiC (0001) substrate was heated to 600 °C under a DC condition of 0.61 A and degassed for 8 h. The vacuum degree of the sample preparation chamber was maintained at 2.5×10 -9 Torr, the single crystal SiC substrate was quickly heated to 1300 °C with a direct current of 2.0 A for 20 mins, and the sample was cooled and set aside.

[0038] The metal Ag source material was heated to 700 °C by a K-Cell evaporation device, the heating current was 1.9 A, and the growth time was 20 mins; The sample is transferred out of the growth chamber and placed upside down in a confined annealing container. The placement method and principle are as follows Figure 1 As shown in the figure, the confined annealing container was heated to 800 °C at a heating rate of 20 °C / min, the annealing time was maintained for 60 mins, and the vacuum degree was maintained at 5.0×10 -1 Torr. Example 2

[0039] The single crystal 6H-SiC (0001) substrate was heated to 650 °C under a DC condition of 0.69 A and degassed for 8 h. The vacuum degree of the sample preparation chamber was maintained at 4.5×10 -9 Torr, the single crystal SiC substrate was quickly heated to 1350 °C with a direct current of 2.1 A for 15 mins, and the sample was cooled and set aside.

[0040] The metal Ag source material was heated to 750 °C using a K-Cell evaporation device, with a heating current of 2.0 A and a growth time of 13 mins. The sample is transferred out of the growth chamber and placed upside down in a confined annealing container. The placement method and principle are as follows Figure 1As shown in the figure, the confined annealing container was heated to 800 °C at a heating rate of 30 °C / min, the annealing time was maintained for 40 mins, and the vacuum degree was maintained at 1.0×10 -1 Torr.

[0041] Figure 3 The SEM characterization results show that the SiC pyrolytic graphene surface presents a uniform circular pattern through the etching of confined metal Ag atoms. SEM characterization shows that during the volatilization of metal Ag nanoparticles, the C atoms in the area combined with metal Ag are etched, thereby leaving a circular etching pattern on the surface of SiC pyrolytic graphene. After high-temperature annealing, the metal Ag nanoparticles evaporate more thoroughly, and there are no metal particles remaining on the surface. The edges of the graphene etched by metal Ag are smooth and clean, with a certain degree of warping. This embodiment illustrates that metal Ag atoms can simply and quickly realize the etching of SiC pyrolytic graphene under confined annealing conditions to obtain a uniform circular pattern. Example 3

[0042] The single crystal 6H-SiC (000-1) substrate with C termination surface was heated to 680 °C under 0.70 A DC condition and degassed for 8 h. The vacuum degree of the sample preparation chamber was maintained at 3.5×10 -9 Torr, the single crystal SiC substrate was quickly heated to 1370 °C with a direct current of 2.2 A for 12 mins, and the sample was cooled and set aside.

[0043] The metal Ag source material was heated to 800 °C using a K-Cell evaporation device with a heating current of 2.3 A and a growth time of 10 mins.

[0044] The sample is transferred out of the growth chamber and placed upside down in a confined annealing container. The placement method and principle are as follows Figure 1 As shown in the figure, the confined annealing container was heated to 850 °C at a heating rate of 25 °C / min, the annealing time was maintained for 35 mins, and the vacuum degree was maintained at 1.5×10 -1 Torr.

[0045] Figure 4 The results of Raman spectroscopy characterization are shown. A circular pattern can be obtained under the etching process conditions, and Raman spectroscopy test was performed at an excitation wavelength of 633 nm. The results show that in the etched area, the characteristic peaks of SiC are mainly presented, as shown in curve B, and there is no Raman characteristic information of graphene; in the unetched area, the Raman characteristic information of graphene is very obvious, as shown in curve A, where the D peak (~1350 cm -1 )、G peak(~1580 cm -1 ), 2D (~2700 cm -1) all show good symmetry and strong strength. This example shows that metal Ag nanoparticles can effectively etch SiC pyrolytic graphene. Example 4

[0046] The single crystal 6H-SiC (000-1) substrate with C termination surface was heated to 680 °C under 0.5 A DC condition and degassed for 8 h. The vacuum degree of the sample preparation chamber was maintained at 3.5×10 -9 Torr, the single crystal SiC substrate was quickly heated to 1350 °C with a direct current of 2.2 A for 15 mins, and the sample was cooled and set aside.

[0047] The metal Ag source material was heated to 850 °C using a K-Cell evaporation device with a heating current of 2.1 A and a growth time of 10 mins.

[0048] The sample is transferred out of the growth chamber and placed upside down in a confined annealing container. The placement method and principle are as follows Figure 1 As shown in the figure, the confined annealing container was heated to 850 °C at a heating rate of 28 °C / min, the annealing time was maintained for 35 mins, and the vacuum degree was maintained at 1.7×10 -1 Torr. Example 5

[0049] The single crystal 6H-SiC (0001) substrate with Si termination surface was heated to 700 °C under 0.70 A DC condition and degassed for 8 h. The vacuum of the sample preparation chamber was maintained at 2.8×10 -9 Torr, the single crystal SiC substrate was quickly heated to 1400 °C with a direct current of 2.5 A for 10 mins, and the sample was cooled and set aside.

[0050] The metal Ag source material was heated to 900 °C using a K-Cell evaporation device with a heating current of 2.2 A and a growth time of 10 mins.

[0051] The sample is transferred out of the growth chamber and placed upside down in a confined annealing container. The placement method and principle are as follows Figure 1 As shown in the figure, the confined annealing container was heated to 900 °C at a heating rate of 22 °C / min, the annealing time was maintained for 30 mins, and the vacuum degree was maintained at 2.7×10 -1 Torr.

[0052] The present invention utilizes the etching technology of metal Ag atoms on the surface of SiC pyrolytic graphene under confined annealing conditions to achieve large-area and uniform etching of graphene on the SiC-based surface. The present invention can solve the technical difficulties of etching Si-face and C-face pyrolytic graphene, and provide ideas for the practical modification and application of SiC pyrolytic graphene.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for etching SiC surface pyrolyzing graphene using metal Ag nanoparticles, characterized in that: The steps include: S1: heat-treating a single crystal SiC substrate to obtain SiC pyrolytic graphene; S2: growing a metal nano-Ag film on the surface of SiC pyrolyzed graphene; S3: placing the SiC pyrolytic graphene with a metal nano-Ag film grown on the surface upside down in a confined annealing container for vacuum high-temperature annealing treatment to achieve etching of the SiC pyrolytic graphene surface by the metal Ag nanoparticles.

2. The method for pyrolyzing graphene on SiC surface by etching with metal Ag nanoparticles according to claim 1, characterized in that: In step S1, the single crystal SiC substrate is pretreated before heat treatment. The pretreatment is to heat the single crystal SiC substrate to 600-700°C under vacuum conditions and keep the temperature for 8 hours.

3. The method for pyrolyzing graphene on SiC surface by etching with metal Ag nanoparticles according to claim 1, characterized in that: In step S1, the heat treatment temperature is 1300-1400°C, and the heat treatment time is 10-20 min.

4. The method for pyrolyzing graphene on SiC surface by etching with metal Ag nanoparticles according to claim 1, characterized in that: In step S2, a metal nano-Ag film is grown on the surface of SiC pyrolytic graphene using a molecular beam epitaxial growth technique. During the molecular beam epitaxial growth process, the heating temperature of the metal Ag source material is 700-900° C., and the growth time is 10-20 min.

5. The method for pyrolyzing graphene on SiC surface by etching with metal Ag nanoparticles according to claim 1, characterized in that: In step S3, when the SiC pyrolytic graphene with a metal nano-Ag film grown on the surface is placed upside down, a small gap is set on the contact surface.

6. The method for pyrolyzing graphene on SiC surface by etching with metal Ag nanoparticles according to claim 1, characterized in that: In step S3, during vacuum high temperature annealing, the vacuum degree range is 1×10 -1 – 5×10 -1 Torr; the heating rate is 20 – 30 ℃ / min, and the sum of the heating time and the holding time does not exceed 1h; the annealing temperature is 800 – 900 ℃, and the annealing time is 30 – 60 min.

7. The method for pyrolyzing graphene on SiC surface by etching with metal Ag nanoparticles according to claim 4, characterized in that: In step S2, the thickness of the grown metal nano-Ag film is 10-20 nm.

8. A SiC pyrolytic graphene with its surface etched by metal Ag nanoparticles, characterized in that: Prepared by the method according to any one of claims 1 to 7.

9. Application of the SiC pyrolytic graphene whose surface is etched by metal Ag nanoparticles as claimed in claim 8 in integrated circuits.

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