A method for preparing a graphite island slider array

Abstract

A method for batch-producing graphite island slider arrays incorporates a grain structure detection step during the manufacturing process. By controlling the subsequent etching step, the sliders have a single, single crystal interface. When sheared, the sliders slide away from this single interface. The slider arrays produced using this method exhibit uniform slip planes and heights, resulting in excellent consistency.

Description

Technical Field

[0001] The present invention relates to the field of super-slip solid structures, and in particular to a method for batch preparing graphite island slider arrays. Background Art

[0002] Friction and wear have long been closely linked not only to the manufacturing industry but also to energy, the environment, and health. According to statistics, approximately one-third of the world's energy is consumed by friction, and approximately 80% of machine component failures are caused by wear. Structural superlubricity is one of the ideal solutions to address friction and wear. Structural superlubricity refers to the phenomenon of near-zero friction and wear between two atomically smooth, incommensurate van der Waals solid surfaces (such as those of two-dimensional materials like graphene and molybdenum disulfide). In 2004, Dutch scientist J. Frenken's research group experimentally measured the friction force of a graphite flake several nanometers (approximately 100 carbon atoms) adhered to a probe sliding on a highly oriented pyrolytic graphite (HOPG) crystal plane, demonstrating the existence of nanoscale superlubricity for the first time. In 2013, Professor Zheng Quanshui first observed superlubricity between HOPG flakes at the micrometer scale, marking the transition of superlubricity from fundamental research to practical technological advancement.

[0003] In the existing process of preparing graphite island slider arrays, since highly oriented pyrolytic graphite (HOPG) has a polycrystalline structure and often contains multiple grain boundaries, the graphite island slider can undergo cleavage and superslip at any of these grain boundaries, making it difficult to determine the position of the slider's slip plane. Due to this factor, the consistency of graphite island slider arrays produced in batches using existing methods is poor. Specifically, this will lead to the following two problems:

[0004] 1. Due to the polycrystalline structure of graphite, during the machining of graphite island sliders, it is possible that one slider may be machined at a location that crosses a grain boundary. In this case, due to the presence of a longitudinal grain boundary within the slider, when the sliders are pushed apart to form a super-slip pair, this longitudinal grain boundary will cause extreme friction, preventing the slider from achieving super-slip sliding and causing failure.

[0005] Furthermore, even if the slider is machined precisely within a single crystal region, the uncertainty of the etching depth may result in the slider containing several horizontal grain boundaries that extend through the slider. These horizontal grain boundaries act as easy slip planes within the slider. When the slider is pushed, it can slide away from any of these horizontal grain boundaries, making the position of these slip planes unknown. When mass-producing large quantities of graphite island sliders, the position and height of their slip planes are inconsistent, making it difficult to consistently control slider quality.

[0006] Technical issues

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for adding a grain structure detection step in the process of preparing a graphite island slider array, and by controlling the subsequent etching steps, there is only one crystal interface inside the slider. When these sliders are sheared, they will slide away from the only crystal interface.

[0008] Technical Solutions

[0009] To achieve the above-mentioned purpose, the present invention provides a technical solution: a method for preparing a graphite island slider array, comprising the following steps:

[0010] Step 1: Covering the highly oriented pyrolytic graphite with at least a photoresist;

[0011] Step 2: patterning the photoresist to retain a plurality of photoresist islands;

[0012] Step 3: etching the highly oriented pyrolytic graphite to remove portions of the highly oriented pyrolytic graphite not protected by the photoresist, thereby forming a plurality of island structures;

[0013] Step 4: removing the residual photoresist to obtain the graphite island slider array;

[0014] It is characterized by:

[0015] Before step 1, the three-dimensional grain structure near the surface of the highly oriented pyrolytic graphite is detected to obtain grain information of the polycrystalline structure near the graphite surface;

[0016] In step three, based on the detected grain information of the polycrystalline structure, the etching time is controlled so that the graphite island slider after etching includes only one layer of horizontal grain boundaries.

[0017] Furthermore, the photoresist in step 1 is preferably covered by spin coating.

[0018] Furthermore, the average diameter of the photoresist islands formed in step 2 is preferably 1 μm to 30 μm, and the average interval between the photoresist islands is preferably 1 μm to 100 μm.

[0019] Furthermore, the etching in step three is reactive ion etching.

[0020] Further said detection is electron backscatter diffraction, X-ray scattering or ellipsometry detection.

[0021] Furthermore, the grain information is grain thickness.

[0022] Furthermore, the etching time is controlled so that the etching depth is just greater than the thickness of a graphite grain on the outermost layer and less than the height from the outermost layer to the bottom of the second grain.

[0023] Furthermore, each graphite island slider (7) has a graphite island top connection layer (9) on its top.

[0024] Furthermore, the connection layer (9) on the top of the graphite island is formed by depositing the connection layer (8) on the highly oriented pyrolytic graphite by plasma chemical vapor deposition.

[0025] Furthermore, the material of the connecting layer (8) is preferably SiO2, and the thickness is preferably 50nm to 500nm.

[0026] Beneficial effects

[0027] As can be seen from the technical solution of the present invention, existing methods for fabricating graphite island slider arrays do not include pre-processing grain structure testing, making it impossible to strictly control the etching depth based on this testing information. As a result, the resulting graphite island slider arrays contain a large number of intergranular interfaces (easy slip planes). As a result, these sliders are not uniform. The slider array fabricated by the present invention has uniform slip planes and heights. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of typical expected results of non-destructive three-dimensional testing of highly oriented pyrolytic graphite of the present invention;

[0029] Figure 2 A schematic diagram of a sample after coating and patterning photoresist according to the present invention;

[0030] Figure 3 This is a schematic diagram of a sample after etching a substrate to form an island array according to the present invention;

[0031] Figure 4 This is a schematic diagram of the sample after the residual photoresist is removed and the graphite island array has a uniform high-slip surface after processing;

[0032] Figure 5 Schematic diagram of a sample with a connecting layer after coating and patterning photoresist according to the present invention;

[0033] Figure 6 This is a schematic diagram showing a sample after etching the connecting layer and the substrate to form an island array;

[0034] Figure 7 Schematic diagram of a sample with a connecting layer after processing according to the present invention.

[0035] Reference numerals:

[0036] Longitudinal grain boundaries extending from the graphite surface to the inside 1 Horizontal grain boundaries inside graphite 2

[0037] Large single crystal area 3 Patterned photoresist 4

[0038] Easy slip surface in graphite islands 5 Graphite island base 6

[0039] Graphite island slider 7 connection layer 8

[0040] Connecting layer 9 on top of graphite islands

[0041] Best Mode for Carrying Out the Invention

[0042] The preparation method of the graphite island slider of the present invention will be described in detail below with reference to the accompanying drawings.

[0043] Step 1: Select highly oriented pyrolytic graphite (HOPG), so that the highly oriented pyrolytic graphite material has a relatively flat surface and a layered structure, and has a large single crystal size and thickness.

[0044] Step 2: Detect the grains near the graphite surface by non-destructive testing of materials, especially the three-dimensional grain structure near the surface, to obtain the polycrystalline structure near the graphite surface. The non-destructive testing method can be, for example, electron backscatter diffraction technology, X-ray scattering technology, elliptical polarization technology, etc. The expected measurement results are as follows: Figure 1 As shown, highly oriented graphite has a polycrystalline, brick-like mosaic structure, comprising several longitudinal grain boundaries 1 extending from the graphite surface into the interior, as well as several horizontal grain boundaries 2 within the graphite. The positions of these grain boundaries can be precisely measured using non-destructive 3D testing techniques. Based on the grain structure information provided by these testing results, a large single crystal region 3 can be accurately selected from the surface of the highly oriented pyrolytic graphite for subsequent preparation steps.

[0045] Step 3: Cover the HOPG with photoresist in sequence. The photoresist can be covered by spin coating.

[0046] Step 4, patterning the photoresist to retain multiple photoresist islands. The step of patterning the photoresist determines the layout of the island structure formed in the subsequent steps. For example, the photoresist can be patterned using an electron beam etching method. The photoresist islands formed can be, for example, a square or circular array with an average diameter of 1 μm to 30 μm and an average spacing of 1 μm to 100 μm between the photoresist islands. In this way, the island structure after etching also has the corresponding average diameter and average spacing, such as Figure 2 shown.

[0047] Step 5, etching the substrate to remove the portion of the substrate not protected by the photoresist, thereby forming a plurality of island structures. The etching method may be, for example, reactive ion etching. Based on the measurement data in step 2, especially the grain thickness data of the region where the island structure is located, the time of reactive ion etching is strictly controlled during the etching process so that the etching depth is just greater than the thickness of a grain of the outermost layer of graphite, such as Figure 3 shown.

[0048] Step 6: Remove the remaining photoresist and complete the processing to obtain a group of graphite island slider arrays. The horizontal grain boundaries inside the graphite have now become a unified slip surface within the graphite island array. Figure 4 Different graphite islands within the same batch of arrays will slide away from the same height when sliding, so they are consistent.

[0049] In particular, each graphite island slider may also have a connecting layer, such as SiO2. The specific preparation method is:

[0050] Step 1: Select highly oriented pyrolytic graphite, which has a flat surface and layered structure, and a large single crystal size and thickness.

[0051] Step 2: Using non-destructive testing methods, the grains near the graphite surface are tested, especially the three-dimensional grain structure near the surface is tested, and the polycrystalline structure near the graphite surface is obtained, such as Figure 1 As shown, a large single crystal region 3 can be accurately selected from the surface of the highly oriented pyrolytic graphite for subsequent preparation.

[0052] Step 3: depositing a connecting layer and applying photoresist on the HOPG layer. The connecting layer may be SiO2, and may have a thickness of, for example, 50 nm to 500 nm. The SiO2 connecting layer may be deposited by plasma chemical vapor deposition. The photoresist may be applied by spin coating.

[0053] Step 4, patterning the photoresist to retain multiple photoresist islands. For example, the photoresist can be patterned using an electron beam etching method. The photoresist islands formed can be, for example, with an average diameter of 1 μm to 30 μm, and an average spacing between the photoresist islands of 1 μm to 100 μm. In this way, the island structure after etching also has a corresponding average diameter and average spacing. The sample after completing the patterning of the photoresist is as follows Figure 5 shown.

[0054] Step 5, sequentially etching the connecting layer and the graphite substrate to remove the connecting layer and part of the graphite that is not protected by the photoresist, thereby forming a plurality of island structures with connecting layers. The etching can be, for example, reactive ion etching. When etching the graphite substrate, the time of reactive ion etching is strictly controlled, and based on the measurement data in step 2, the etching depth is just greater than the thickness of a grain of the surface layer of graphite and less than the height from the surface layer to the bottom of the second grain. Figure 6 shown.

[0055] Step 6: Remove the residual photoresist and complete the processing to obtain a batch of graphite island slider arrays with connecting layers, which have a uniform sliding surface, such as Figure 7 shown.

[0056] Industrial Applicability

[0057] The above descriptions are merely preferred embodiments of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention shall fall within the scope of the claims of the present invention.

Claims

1. A method for preparing a graphite island slider array, comprising the following steps: Step 1: Covering the highly oriented pyrolytic graphite with at least a photoresist; Step 2: patterning the photoresist to retain a plurality of photoresist islands; Step 3: etching the highly oriented pyrolytic graphite to remove portions of the highly oriented pyrolytic graphite not protected by the photoresist, thereby forming a plurality of island structures; Step 4: removing the residual photoresist to obtain the graphite island slider array; It is characterized in that Before step 1, the three-dimensional grain structure near the surface of the highly oriented pyrolytic graphite is detected to obtain grain information of the polycrystalline structure near the graphite surface; In step three, based on the grain information of the polycrystalline structure detected above, the etching is controlled so that the graphite island slider (7) after etching includes only one layer of horizontal grain boundaries.

2. The preparation method according to claim 1, characterized in that The photoresist in step 1 is preferably covered by spin coating.

3. The preparation method according to claim 1, characterized in that The average diameter of the photoresist islands formed in step 2 is 1 μm to 30 μm, and the average interval between the photoresist islands is 1 μm to 100 μm.

4. The preparation method according to claim 1, characterized in that The etching in step three is reactive ion etching.

5. The preparation method according to claim 1, characterized in that The detection is electron backscatter diffraction, X-ray scattering or ellipsometry detection.

6. The preparation method according to claim 1, characterized in that The grain information is the grain thickness.

7. The preparation method according to claim 6, characterized in that The etching time is controlled so that the etching depth is just greater than the thickness of a graphite grain on the outermost layer and less than the height from the outermost layer to the bottom of the second grain.

8. The preparation method according to any one of claims 1 to 7, characterized in that Each graphite island slider (7) has a graphite island top connection layer (9) on its top.

9. The preparation method according to claim 8, characterized in that The connection layer (9) on the top of the graphite island is formed by depositing the connection layer (8) on the highly oriented pyrolytic graphite through a plasma chemical vapor deposition method.

10. The preparation method according to claim 9, characterized in that The material of the connecting layer (8) is preferably SiO2, and the thickness is 50nm to 500nm.

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