Method for removing residual adhesive on surface of two-dimensional material after mechanical cleavage of adhesive tape

Abstract

The invention provides a method for removing residual adhesive on the surface of a two-dimensional material after mechanical cleavage of an adhesive tape, which comprises the following steps: annealing the two-dimensional material with the residual adhesive on the surface after mechanical cleavage of the adhesive tape, carrying out programmed heating on the to-be-treated two-dimensional material at a preset heating speed until a preset temperature is reached, and carrying out heat preservation; and then rapidly cooling to the room temperature at the cooling speed of 5 DEG C / min or above. By means of the annealing process, the residual glue remaining on the surface of the two-dimensional material in the mechanical mechanism process can be effectively removed, the removal effect of large-particle residual glue is good, the removal effect of small-particle residual glue can be remarkably improved, and the problem that the residual glue removal effect of a natural cooling annealing process is poor is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of removing residual adhesive on the surface of two-dimensional materials, and specifically relates to a method for removing residual adhesive on the surface of two-dimensional materials after mechanical cleavage of an adhesive tape. Background Art

[0002] Two-dimensional material / semiconductor contact diodes have become the preferred materials for the next generation of semiconductor diodes and a wider range of electronic devices due to their excellent electrical properties, promoting the innovation of electronic and optoelectronic technologies. In order to obtain high-quality two-dimensional materials, it is usually necessary to use tape mechanical cleavage technology to cleave block or thick layer two-dimensional materials (such as graphene, boron nitride, etc.) into single-layer or few-layer two-dimensional materials for research and application. Although this cleavage technology can quickly obtain large blocks of almost defect-free thin layers of two-dimensional materials, it is very easy to leave residual glue on the surface of the two-dimensional material after cleavage with tape, and it is difficult to remove. At present, tubular furnace heat treatment is usually used to remove residual colloid on the surface of two-dimensional materials, but the effect is not good. Summary of the invention

[0003] In order to solve all or part of the above technical problems, the present invention provides the following technical solutions:

[0004] One of the purposes of the present invention is to provide a method for removing residual adhesive on the surface of a two-dimensional material after mechanical cleavage of a tape, comprising annealing the two-dimensional material having residual adhesive on the surface after mechanical cleavage of a tape, wherein the annealing comprises: in a first mixed atmosphere containing hydrogen and argon, heating the two-dimensional material to be treated at a preset heating rate until a preset temperature is reached and the temperature is kept constant; and then rapidly cooling the temperature to room temperature at a cooling rate of more than 5°C / min.

[0005] After systematic research, the present invention has found that the effect of removing residual glue on the surface of two-dimensional materials by annealing process is related to the cooling rate in the cooling stage. If it is naturally cooled to room temperature after the insulation is completed, it usually takes 10-14 hours. Not only is the time cost high, but there is still a lot of residual glue on the surface of the two-dimensional material, and the removal effect is poor. The present invention unexpectedly found that the effect of removing residual glue by annealing process can be improved by speeding up the cooling rate, especially when the cooling rate is increased to more than 5°C / min, the residual glue on the surface of the two-dimensional material can be significantly removed.

[0006] In some embodiments, the cooling rate is 5 to 25°C / min, for example, 5 to 10°C / min, 10 to 15°C / min, or 20 to 25°C / min.

[0007] In some preferred embodiments, the cooling rate is 10-15° C. / min.

[0008] The present invention compares the residual glue removal effects in three temperature ranges of cooling rates of 5-10°C / min, 10-15°C / min, and 20-25°C / min, and finds that, although compared with natural cooling, the residual glue removal effect can be improved when the cooling rate is controlled at 5-25°C / min, the effect in the cooling range of 10-15°C / min is better, and the surface of the two-dimensional material can be basically free of residual glue.

[0009] In some embodiments, the heating rate is 5 to 15° C. / min, such as 5 to 8° C. / min, 10 to 15° C. / min.

[0010] In some preferred embodiments, the heating rate is 5-8°C / min.

[0011] The program heating at a rate of 5 to 15°C / min can reduce the large particles of residual glue on the surface of the material, and the subsequent program cooling can further remove the small particles of residual glue, so that the overall residual glue removal effect is excellent. However, the present invention further found that if the speed of the heating stage is fast, although the large particles of residual glue can be effectively removed, the fast heating speed will make the small particles of residual glue more closely combined with the two-dimensional material, which increases the difficulty of removing the small particles of residual glue in the subsequent cooling stage. Therefore, the heating speed of the heating stage should not be too fast, and 5 to 8°C / min is preferred.

[0012] In some embodiments, the volume ratio of hydrogen to argon in the first mixed atmosphere is 3-4:7-6, such as 3:7, 3.5:6.5, 4:6. The hydrogen in the first mixed atmosphere can effectively decompose organic colloids as a reducing agent and convert them into simpler compounds and gases (such as water vapor).

[0013] In some embodiments, during the annealing process, the first mixed atmosphere is continuously introduced at a gas flow rate of 1 to 1.5 L / min.

[0014] In some embodiments, the preset temperature is 300-450° C., that is, the temperature is increased to 300-450° C. at a preset heating rate and then kept warm.

[0015] In some embodiments, the insulation time is more than 2 hours.

[0016] In some embodiments, the method specifically includes: placing the two-dimensional material to be processed in a tubular furnace, and introducing an inert atmosphere into the tubular furnace to exhaust the air therein, and then evacuating the tubular furnace; introducing the first mixed gas into the tubular furnace, raising the temperature to 300-450°C at a heating rate of 5-8°C / min and keeping it warm for more than 2 hours; then cooling down to room temperature at a cooling rate of 10-15°C / min to remove residual glue on the surface of the two-dimensional material.

[0017] In some embodiments, the method specifically includes: placing the two-dimensional material to be treated in a tube furnace, and introducing an inert atmosphere into the tube furnace to exhaust the air therein, and then evacuating the tube furnace; introducing the first mixed atmosphere into the tube furnace, heating the temperature to 300-450°C at a heating rate of 5-8°C / min and keeping it warm for 1.5-2h; after the insulation time is reached, the first mixed atmosphere is quickly replaced with an argon atmosphere within 5min, and then oxygen is introduced to form a second mixed atmosphere with an oxygen-argon content of 1:10-1:5 within 10min; then the temperature is reduced to room temperature at a cooling rate of 10-15°C / min to remove the residual glue on the surface of the two-dimensional material. Before the rapid cooling, the first mixed atmosphere is replaced with the second mixed atmosphere, and the low concentration of oxygen in the second mixed atmosphere can be used to oxidize the residual organic matter at high temperature, and the hydrogen adsorbed by the two-dimensional material is also removed, so as to prevent hydrogen from causing changes in the properties of the two-dimensional material. Especially when the two-dimensional material is graphene, this specific operation step is preferably adopted to prevent the graphene from generating hydrogenated graphene under the action of hydrogen, which may cause performance changes.

[0018] In some embodiments, the residual adhesive on the surface of the two-dimensional material may be a photoresist such as PVA, PMMA, or a blue film tape, a transparent tape, or a combination of more.

[0019] In some embodiments, the two-dimensional material is graphene, boron nitride or molybdenum disulfide.

[0020] In some embodiments, the number of layers of the two-dimensional material is 1 to 20, or the thickness of the two-dimensional material is less than 6.5 nm. That is, the method provided by the present invention is applicable to a few layers and thinner two-dimensional material after mechanical cleavage, and effectively removes the residual adhesive on its surface without damaging the two-dimensional material.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects: the annealing process provided by the present invention can effectively remove the residual glue remaining on the surface of the two-dimensional material during the mechanical mechanism process, and not only has a good removal effect on large-particle residual glue, but can also significantly improve the removal effect of small-particle residual glue, thereby solving the problem of poor removal effect of residual glue by the natural cooling annealing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1a, Figure 1b are the AFM images of the two-dimensional material without annealing after mechanical cleavage of the tape at different magnifications;

[0024] Figure 2 is an AFM image of the two-dimensional material after annealing treatment in Example 1;

[0025] Figure 3 is an AFM image of the two-dimensional material after annealing treatment in Example 2;

[0026] Figure 4 is an AFM image of the two-dimensional material after annealing treatment in Example 3;

[0027] Figure 5 is an AFM image of the two-dimensional material after annealing treatment in Example 4;

[0028] Figure 6 is an AFM image of the two-dimensional material after annealing treatment in Comparative Example 1;

[0029] Figure 7 is an AFM image of the two-dimensional material after annealing treatment in Comparative Example 2;

[0030] Figure 8 is a partially enlarged AFM image of residual adhesive on the surface of the two-dimensional material after annealing in Comparative Example 2;

[0031] Fig. 9 , Fig.10 is an AFM image of the two-dimensional material after annealing treatment in Comparative Example 2 under 100 nm scale conditions;

[0032] Fig.11 This is the AFM image of the two-dimensional material after annealing treatment in Comparative Example 3. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is described in detail below in conjunction with specific embodiments so that those skilled in the art can better understand and implement the technical solution of the present invention. The specific functional details disclosed herein should not be interpreted as limiting, but only as the basis for the claims and as a representative basis for teaching those skilled in the art to adopt the present invention in different ways in any appropriate detailed embodiment.

[0034] In addition, unless otherwise specified, the various raw materials used in the following examples can be purchased from the market and other channels, and the various production and testing equipment used are also equipment known in the art.

[0035] Example 1

[0036] This embodiment provides a method for removing residual adhesive on the surface of a two-dimensional material after mechanical cleavage of an adhesive tape, which specifically includes the following steps:

[0037] The boron nitride with residual glue on the surface was placed in a tubular furnace, the tubular furnace was evacuated, and argon gas was introduced into the tubular furnace for 15 minutes; then a mixed gas of hydrogen and argon was introduced into the tubular furnace at a flow rate of 1L / min, and the volume ratio of hydrogen to argon was 3:7. The temperature was programmed to rise at a rate of 5°C / min until the temperature reached 300°C, and the temperature was kept in the mixed atmosphere for 2 hours; then the temperature was rapidly cooled at a cooling rate of 10°C / min.

[0038] Figure 1a , Figure 1b These are AFM images of the two-dimensional material before annealing at different magnifications. Figure 2 This is an AFM image of the two-dimensional material after annealing treatment in this embodiment. It can be seen that after annealing treatment in this embodiment, there is basically no white spot on the surface of the two-dimensional material, that is, there is basically no residual glue.

[0039] Example 2

[0040] Example 2 is substantially the same as Example 1, except that the cooling rate of Example 2 is 15° C. / min. The rest is implemented in the same manner as Example 1, and will not be described in detail herein.

[0041] Figure 3 This is an AFM image of the two-dimensional material after annealing treatment in this embodiment. It can be seen that the surface of the two-dimensional material is relatively clean, with basically no residual glue remaining, and the effect is equivalent to that of Example 1.

[0042] Example 3

[0043] Example 3 is substantially the same as Example 1, except that the cooling rate of Example 3 is 20° C. / min. The rest is implemented in the same manner as Example 1, and will not be described in detail herein.

[0044] Figure 4 This is an AFM image of the two-dimensional material after annealing treatment in this embodiment. It is found that when the cooling rate is faster, although a part of the residual glue can be removed, compared with Embodiment 1 and Embodiment 2, more residual glue remains on the surface of the two-dimensional material treated in this embodiment.

[0045] The present invention also tested the effect of a cooling rate of 25°C / min and found that the effect was equivalent to that of a cooling rate of 20°C / min, that is, although a portion of the residual glue could be removed, the effect was reduced compared with Examples 1 and 2.

[0046] Example 4

[0047] Example 4 is substantially the same as Example 1, except that the cooling rate of Example 4 is 5°C / min. The rest is implemented in the same manner as Example 1, and will not be described in detail herein.

[0048] Figure 5 This is an AFM image of the two-dimensional material after annealing treatment in this embodiment. It is found that when the cooling rate is slow, although a part of the residual glue can be removed, compared with Embodiment 1 and Embodiment 2, more residual glue remains on the surface of the two-dimensional material treated in this embodiment.

[0049] By comparing the effects of Examples 1-4, it is found that the residual adhesive removal effect is better when the temperature is lowered at a rate of 10-15°C / min.

[0050] Example 5

[0051] Example 5 is substantially the same as Example 1, except that the heating rate of Example 5 is 8° C. / min. The rest is implemented in the same manner as Example 1, and will not be described again.

[0052] The residual adhesive removal effect of Example 5 is equivalent to that of Example 1.

[0053] Example 6

[0054] Example 6 is substantially the same as Example 1, except that the heating rate of Example 6 is 10° C. / min. The rest is implemented in the same manner as Example 1, and will not be described in detail herein.

[0055] By comparing Example 1 and Example 6, it is found that although this example can remove a portion of the residual glue, compared with Example 1, more residual glue remains on the surface of the two-dimensional material treated by this example.

[0056] Example 7

[0057] Example 7 is substantially the same as Example 1, except that the heating rate of Example 7 is 15° C. / min. The rest is implemented in the same manner as Example 1, and will not be described in detail herein.

[0058] By comparing Example 1 and Example 7, it is found that although this Example can remove a portion of the residual adhesive, more residual adhesive remains on the surface of the two-dimensional material treated by this Example than in Example 1. The effects of Example 7 and Example 6 are basically equivalent.

[0059] Example 8

[0060] Example 8 is substantially the same as Example 1, except that the volume ratio of hydrogen to argon in the mixed gas of Example 8 is 4:6. The rest is implemented in the same manner as Example 1 and will not be described in detail herein.

[0061] The residual adhesive removal effect of Example 8 is equivalent to that of Example 1.

[0062] Example 9

[0063] Example 9 is basically the same as Example 1, except that the annealing temperature of Example 9 is 450° C., that is, the temperature is programmed to rise at a rate of 5° C. / min until the temperature reaches 450° C. and then maintained. The rest is implemented in the same manner as Example 1 and will not be described again.

[0064] The residual adhesive removal effect of Example 9 is equivalent to that of Example 1.

[0065] Example 10

[0066] Example 10 is basically the same as Example 1, except that the annealing temperature of Example 10 is 400° C., that is, the temperature is programmed to rise at a rate of 5° C. / min until the temperature reaches 400° C. and then maintained. The rest is implemented in the same manner as Example 1 and will not be described again.

[0067] The residual adhesive removal effect of Example 10 is equivalent to that of Example 1.

[0068] Embodiment 11

[0069] The graphene with residual glue on the surface was placed in a tube furnace, the tube furnace was evacuated, and argon gas was introduced into the tube furnace for 15 minutes; then a mixed gas of hydrogen and argon was introduced into the tube furnace at a flow rate of 1L / min, the volume ratio of hydrogen to argon was 3:7, and the temperature was programmed at a rate of 5℃ / min until the temperature reached 300℃, and the temperature was kept in the mixed atmosphere for 1.5 hours;

[0070] After the holding time is reached, the mixed gas of hydrogen and argon is quickly replaced with an argon atmosphere within 5 minutes, and then oxygen is introduced to form a mixed atmosphere with an oxygen-argon content of 1:10 within 10 minutes; then the temperature is rapidly cooled at a cooling rate of 10°C / min.

[0071] Example 12

[0072] The graphene with residual glue on the surface was placed in a tube furnace, the tube furnace was evacuated, and argon gas was introduced into the tube furnace for 15 minutes; then a mixed gas of hydrogen and argon was introduced into the tube furnace at a flow rate of 1L / min, the volume ratio of hydrogen to argon was 4:6, and the temperature was programmed at a rate of 8℃ / min until the temperature reached 450℃, and the temperature was kept in the mixed atmosphere for 2 hours;

[0073] After the holding time is reached, the mixed gas of hydrogen and argon is quickly replaced with an argon atmosphere within 5 minutes, and then oxygen is introduced to form a mixed atmosphere with an oxygen-argon content of 1:5 within 10 minutes; then the temperature is rapidly cooled at a cooling rate of 10°C / min.

[0074] Embodiment 11 and Embodiment 12 can utilize low concentration of oxygen in the oxygen-argon mixed atmosphere to oxidize the organic matter remaining on the graphene at high temperature and remove hydrogen adsorbed by the graphene to prevent hydrogen from causing changes in the properties of the graphene.

[0075] Comparative Example 1

[0076] The two-dimensional material with residual glue on the surface is placed in a tubular furnace, the tubular furnace is evacuated, and argon gas is introduced into the tubular furnace for 15 minutes; the temperature is programmed to rise at a rate of 5°C / min until the temperature reaches 300°C, and is kept in the mixed atmosphere for 2 hours; then the temperature is naturally cooled to room temperature (the time required for natural cooling is about 10 hours).

[0077] Figure 6 This is the residual glue remaining on the surface of the two-dimensional material after annealing treatment in Comparative Example 1. It is found that there are still a lot of white dot-shaped residual glue that cannot be removed.

[0078] Comparative Example 2

[0079] The two-dimensional material with residual glue on the surface is placed in a tubular furnace, the tubular furnace is evacuated, and argon gas is introduced into the tubular furnace for 15 minutes; the temperature is programmed to rise at a rate of 10°C / min until the temperature reaches 300°C, and is kept in a mixed atmosphere for 2 hours; then the temperature is naturally cooled to room temperature (the time required for natural cooling is about 10 hours).

[0080] Figure 7 This is the AFM image of the two-dimensional material surface after annealing treatment in Comparative Example 2. Figure 8 It is a local image of the residual glue on the surface of the two-dimensional material. Figure 7 , Figure 8 It can be seen that compared with Comparative Example 1, the large particles of residual adhesive on the surface of the two-dimensional material are reduced, but there are still some fine granular residual adhesive remaining.

[0081] Fig. 9 , Fig.10 This is an AFM image observed under 100nm scale conditions. It is found that compared with heating at a rate of 5℃ / min, program heating at a rate of 10℃ / min causes the granular residual adhesive to adhere more closely to the surface of the two-dimensional material. By comparing Example 5, Example 6 and Comparative Example 2, it can be seen that compared with Comparative Example 2, although the granular residual adhesive in Examples 5 and 6 is reduced after rapid program cooling, the overall residual adhesive removal effect is inferior to that in Example 1. This may be due to the fast heating stage, which causes the granular residual adhesive to adhere closely to the material, affecting the removal effect of the residual adhesive in the cooling stage.

[0082] Comparative Example 3

[0083] The two-dimensional material with residual glue on the surface is placed in a tubular furnace, the tubular furnace is vacuumed, and argon gas is introduced into the tubular furnace for 15 minutes; a mixed gas of hydrogen and argon is introduced into the tubular furnace, and the volume ratio of hydrogen to argon is 3:7. The temperature is programmed to rise at a rate of 5°C / min until the temperature reaches 300°C, and then the temperature is naturally cooled to room temperature (the natural cooling time required is about 10 hours).

[0084] Fig.11 This is an AFM image of the two-dimensional material surface after annealing treatment in Comparative Example 3. It is found that compared with Comparative Example 1, the amount of residual glue remaining is reduced, but compared with Example 1, there are still more granular residual glue that has not been removed.

[0085] The various aspects, embodiments, features and examples of the present invention should be considered as illustrative in all aspects and are not intended to limit the present invention, the scope of the present invention is defined only by the claims. Other embodiments, modifications and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.

[0086] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0087] Although the present invention has been described with reference to illustrative embodiments, it will be appreciated by those skilled in the art that various other changes, omissions and / or additions may be made without departing from the spirit and scope of the present invention and that the elements of the embodiments may be replaced by substantial equivalents. In addition, many modifications may be made without departing from the scope of the present invention to adapt specific circumstances or materials to the teachings of the present invention. Therefore, it is not intended herein to limit the present invention to the disclosed specific embodiments for performing the present invention, but it is intended that the present invention will include all embodiments within the scope of the appended claims. In addition, unless specifically stated, any use of the terms first, second, etc. does not indicate any order or importance, but rather uses the terms first, second, etc. to distinguish one element from another.

Claims

1. A method for removing residual adhesive on the surface of a two-dimensional material after mechanical cleavage of an adhesive tape, characterized in that: The method comprises annealing a two-dimensional material having residual adhesive on the surface after mechanical cleavage of an adhesive tape, wherein the annealing comprises: in a first mixed atmosphere containing hydrogen and argon, heating the two-dimensional material to be treated at a preset heating rate until a preset temperature is reached and the temperature is kept constant; and then the temperature is rapidly cooled to room temperature at a cooling rate of more than 5°C / min.

2. The method according to claim 1, characterized in that: The cooling rate is 5 to 25° C. / min.

3. The method according to claim 2, characterized in that: The cooling rate is 10-15°C / min.

4. The method according to claim 1, characterized in that: The heating rate is 5 to 15° C. / min.

5. The method according to claim 4, characterized in that: The heating rate is 5 to 8°C / min.

6. The method according to claim 1, characterized in that: The volume ratio of hydrogen to argon in the first mixed atmosphere is 3-4:7-6; And / or, during the annealing process, the first mixed atmosphere is continuously introduced at a gas flow rate of 1 to 1.5 L / min.

7. The method according to claim 1, characterized in that: The preset temperature is 300-450° C.; and / or the heat preservation time is more than 2 hours.

8. The method according to claim 1, characterized in that: Specifically include: placing the two-dimensional material to be processed in a tube furnace, introducing an inert atmosphere into the tube furnace to exhaust the air therein, and then evacuating the tube furnace; The first mixed atmosphere is introduced into the tubular furnace, and the temperature is raised to 300-450°C at a heating rate of 5-8°C / min and kept at this temperature for more than 2 hours; then the temperature is lowered to room temperature at a cooling rate of 10-15°C / min to remove residual glue on the surface of the two-dimensional material.

9. The method according to claim 1, characterized in that: Specifically include: placing the two-dimensional material to be processed in a tube furnace, introducing an inert atmosphere into the tube furnace to exhaust the air therein, and then evacuating the tube furnace; The first mixed atmosphere is introduced into the tubular furnace, and the temperature is raised to 300-450° C. at a heating rate of 5-8° C. / min and kept at this temperature for 1.5-2 hours; After the holding time is reached, the first mixed atmosphere is quickly replaced with an argon atmosphere within 5 minutes, and then oxygen is introduced to form a second mixed atmosphere with an oxygen-argon content of 1:10 to 1:5 within 10 minutes; Then, the temperature is lowered to room temperature at a rate of 10 to 15° C. / min to remove residual glue on the surface of the two-dimensional material.

10. The method according to any one of claims 1 to 9, characterized in that: The two-dimensional material is graphene, boron nitride or molybdenum disulfide.

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