A low-cost large-area graphene patterning method

Abstract

The present invention belongs to the field of semiconductor processing technology, and specifically relates to a low-cost large-area graphene patterning method, comprising the following steps: S1, depositing a layer of aluminum metal as a mask on the surface of a substrate to which a graphene film has been transferred; S2, spin coating a layer of photoresist and photolithography to pattern the aluminum metal mask; S3, etching graphene; S4, cleaning the remaining photoresist and corroding the remaining aluminum metal mask. The present invention uses a metal mask to separate graphene from the photoresist, thereby avoiding direct contact between graphene and photoresist to cause photoresist residue. The obtained graphene surface is cleaner and more consistent. In large-area graphene, the clean and consistent surface ensures the consistency of its electrical, mechanical and other properties, so it is suitable for large-area graphene patterning. The present invention uses aluminum metal material as a mask material, and its material cost is low, and the additional material cost in large-area graphene patterning is limited.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor processing, and in particular relates to a low-cost large-area graphene patterning method. Background Art

[0002] Graphene film is a new type of two-dimensional material with a single layer of carbon atoms tightly stacked into a honeycomb lattice structure. It has many excellent properties in mechanics, electricity, thermodynamics, etc., which are manifested in its high strength, good toughness, high carrier mobility, high thermal conductivity, etc. Utilizing these excellent properties of graphene film materials, a variety of new sensors and high-performance transistors have been developed.

[0003] The production of these devices requires graphene patterning. Graphene patterning is usually done by spin coating photoresist on graphene, then using a mask plate for photolithography and plasma patterning. Since the photoresist is in direct contact with graphene and graphene has strong adsorption properties, the photoresist will inevitably remain on the graphene, seriously affecting the performance of the device.

[0004] At present, in order to clean the residual photoresist on graphene, ultraviolet ozone treatment, plasma cleaning and other methods are used, but these methods are not only costly, but also unable to completely remove the residual photoresist, and some may even cause defects in the graphene film. In order to avoid photoresist residue and graphene damage, many new methods have been proposed, no longer focusing on how to clean graphene to remove photoresist, but avoiding contact between photoresist and graphene. The invention patent with patent number: ZL201610546722.6 discloses a method for controlling the directional movement of oxygen excitons, thereby regulating the etching of graphene to obtain graphene graphics. Although this method does not require the use of photolithography to process graphene, it effectively avoids the residue of photoresist, but oxygen excitons have the disadvantages of low control accuracy and slow patterning rate, resulting in low graphene graphics accuracy and even damage to graphene. In addition, this method requires additional etching equipment, which increases costs and has great limitations. Summary of the invention

[0005] In view of the technical problems that the above-mentioned existing graphene etching methods easily lead to low graphene pattern accuracy and even cause damage to graphene, and the method requires additional etching equipment, which increases the cost and has great limitations, the present invention provides a low-cost large-area graphene patterning method with low cost, simple process, large-area graphene patterning, and a cleaner and more consistent graphene surface.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A low-cost large-area graphene patterning method comprises the following steps:

[0008] S1, depositing a layer of aluminum metal as a mask on the surface of the substrate to which the graphene film is transferred;

[0009] S2, spin-coating a layer of photoresist and photolithography to pattern the aluminum metal mask;

[0010] S3, etching graphene;

[0011] S4, cleaning the remaining photoresist and corroding the remaining aluminum metal mask.

[0012] The method of depositing a layer of aluminum metal as a mask in S1 is: transferring the graphene film to the substrate, and depositing a layer of aluminum metal mask on the graphene film by evaporation.

[0013] The evaporation method is electron beam evaporation or thermal evaporation, and the deposition thickness of the aluminum metal mask is in the range of 5-40 nm.

[0014] The substrate in S1 is made of silicon, glass, quartz, sapphire, silicon carbide or flexible material, and a silicon dioxide layer or a silicon nitride layer is deposited on the substrate.

[0015] The method of spin coating a layer of photoresist and performing photolithography in S2 is: spin coating a layer of photoresist on the surface of the aluminum metal mask, photolithographing and developing the photoresist to obtain a photoresist pattern, and then etching the aluminum metal mask to obtain an aluminum metal mask pattern.

[0016] The photoresist is AZ5214E ​​positive photoresist or AZ P4620 positive photoresist, and the developing photoresist is a composite organic alkali developer that slows down aluminum corrosion.

[0017] The method for etching the aluminum metal mask is: using boron trichloride and chlorine metal dry method to etch the aluminum metal mask to obtain the aluminum metal mask pattern.

[0018] The method for etching graphene in S3 is: using oxygen plasma to etch the graphene film to obtain a graphene pattern.

[0019] The method for cleaning the remaining photoresist in S4 is: using acetone to heat in a 50° C. water bath for 5 minutes and using anhydrous ethanol to heat in a 50° C. water bath for 3 minutes to clean the photoresist pattern.

[0020] The method for corroding the remaining aluminum metal mask in S4 is: using an aluminum corrosion solution to corrode the remaining aluminum metal mask, wherein the aluminum corrosion solution is diluted hydrochloric acid, phosphoric acid or diluted tetramethylammonium hydroxide.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention uses a metal mask to separate graphene from photoresist, thereby avoiding direct contact between graphene and photoresist and causing photoresist residue. The obtained graphene surface is cleaner and more consistent. In large-area graphene, the clean and consistent surface ensures the consistency of its electrical, mechanical and other properties, so it is applicable to large-area graphene patterning.

[0023] 2. The present invention uses aluminum metal material as the mask material, which has low material cost and has limited additional material cost in large-area graphene patterning.

[0024] 3. The present invention uses electron beam evaporation, thermal evaporation and other methods to deposit aluminum metal. This method is not only suitable for metal growth on the surface of various sizes including large-sized wafers, but also has simple equipment operation, low cost, and will not damage the graphene surface.

[0025] 4. The present invention uses boron trichloride and chlorine metal dry etching of the aluminum mask, which can effectively avoid side etching and improve device accuracy.

[0026] 5. The present invention uses dilute acid or dilute tetramethylammonium hydroxide to corrode the remaining aluminum. The dilute acid and dilute tetramethylammonium hydroxide solutions will not react with graphene and affect the performance of graphene, and are widely used in process processing with low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0028] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0029] Figure 1 A schematic diagram of depositing an aluminum metal mask and spin-coating a photoresist on graphene on a substrate of the present invention;

[0030] Figure 2 is a schematic diagram of a patterned metal mask of the present invention;

[0031] Figure 3 A schematic diagram of etching graphene according to the present invention;

[0032] Figure 4 This is a schematic diagram of patterning graphene after removing the photoresist and the metal mask according to the present invention.

[0033] Among them: 1 is a substrate, 2 is a graphene film, 3 is an aluminum metal mask, 4 is a photoresist, 5 is a photoresist image, 6 is an aluminum metal mask pattern, and 7 is a graphene pattern. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. These descriptions are only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0035] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0036] The present invention provides a low-cost large-area graphene patterning method, which can be used for graphene patterning in devices such as graphene sensors and graphene transistors. The method uses metal as a mask to isolate photoresist, thereby preventing the photoresist from directly contacting the graphene and causing photoresist residues to affect device performance.

[0037] A graphene patterning method according to an embodiment of the present invention, as Figure 1 As shown, the graphene film 2 is transferred to the silicon dioxide substrate 1. A layer of aluminum metal mask 3 is deposited on the graphene film 2, and in particular, a 20 nm aluminum metal mask 3 is deposited on the graphene film 2 by evaporation. Preferably, the evaporation method includes but is not limited to electron beam evaporation and thermal evaporation. A photoresist 4 is spin-coated on the aluminum metal mask 3. In particular, a positive photoresist can be spin-coated on the surface of the aluminum mask 3. Preferably, the positive photoresist includes but is not limited to AZ 5214E ​​and AZP4620.

[0038] like Figure 2 As shown, after photolithography and development of the photoresist 4, a photoresist pattern 5 is obtained. In particular, a composite organic alkali developer that slows down aluminum corrosion can be used to develop the photoresist 4. Boron trichloride and chlorine metal dry etching are used to obtain an aluminum metal mask pattern 6.

[0039] like Figure 3 As shown, the graphene film 2 is etched using oxygen plasma to obtain a graphene pattern 7.

[0040] like Figure 4As shown, the remaining photoresist pattern 5 is cleaned, and in particular, acetone is heated in a water bath at 50° C. for 5 minutes and anhydrous ethanol is heated in a water bath at 50° C. for 3 minutes to clean the photoresist pattern 5. The remaining aluminum metal mask pattern 6 is corroded, and preferably, the aluminum etching solution includes but is not limited to dilute hydrochloric acid, phosphoric acid and dilute tetramethylammonium hydroxide. The entire graphene patterning process is completed.

[0041] The graphene patterning method provided by the embodiment of the present invention can avoid the direct contact between the photoresist and the graphene, which causes the graphene residue and leads to the performance degradation of the graphene sensitive unit. The method can be used to pattern the graphene and obtain a cleaner and more consistent graphene surface. In large-area graphene, the cleaner and more consistent surface ensures the consistency of the electrical, mechanical and other properties of each unit graphene, so it is also applicable to large-area graphene patterning.

[0042] The present invention uses aluminum metal as the mask material, and its metal coating equipment is simple and low-cost, and can be used for metal growth on the surface of various sizes including large-sized wafers. Moreover, its material cost is also low, and the additional cost in large-area patterned graphene is limited.

[0043] The silicon dioxide substrates in the embodiments of the present invention can be replaced by silicon nitride, quartz, etc., and the aluminum metal masks can be replaced by aluminum oxide masks, etc. Various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and purpose of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

[0044] Only the preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention, and various changes should be included in the protection scope of the present invention.

Claims

1. A low-cost large-area graphene patterning method, characterized in that: The following steps are involved: S1, depositing a layer of aluminum metal as a mask on the surface of the substrate to which the graphene film is transferred; S2, spin-coating a layer of photoresist and photolithography to pattern the aluminum metal mask; S3, etching graphene; S4, cleaning the remaining photoresist and corroding the remaining aluminum metal mask; The method of spin coating a layer of photoresist and performing photolithography in S2 is: spin coating a layer of photoresist on the surface of the aluminum metal mask, photolithography and developing the photoresist to obtain a photoresist pattern, and then etching the aluminum metal mask to obtain an aluminum metal mask pattern; The method for etching the aluminum metal mask is: using boron trichloride and chlorine metal dry etching to obtain an aluminum metal mask pattern; The method for etching graphene in S3 is: using oxygen plasma to etch the graphene film to obtain a graphene pattern.

2. A low-cost large-area graphene patterning method according to claim 1, characterized in that: The method of depositing a layer of aluminum metal as a mask in S1 is: transferring the graphene film to the substrate, and depositing a layer of aluminum metal mask on the graphene film by evaporation.

3. A low-cost large-area graphene patterning method according to claim 2, characterized in that: The evaporation method is electron beam evaporation or thermal evaporation, and the deposition thickness of the aluminum metal mask is in the range of 5-40 nm.

4. A low-cost large-area graphene patterning method according to claim 1, characterized in that: The substrate in S1 is made of silicon, glass, quartz, sapphire, silicon carbide or flexible material, and a silicon dioxide layer or a silicon nitride layer is deposited on the substrate.

5. The low-cost large-area graphene patterning method according to claim 1, characterized in that: The photoresist adopts AZ5214E ​​positive photoresist or AZP4620 positive photoresist, and the developing photoresist adopts a composite organic alkali developer that slows down aluminum corrosion.

6. A low-cost large-area graphene patterning method according to claim 1, characterized in that: The method for cleaning the remaining photoresist in S4 is: using acetone to heat in a 50° C. water bath for 5 minutes and using anhydrous ethanol to heat in a 50° C. water bath for 3 minutes to clean the photoresist pattern.

7. The low-cost large-area graphene patterning method according to claim 1, characterized in that: The method for corroding the remaining aluminum metal mask in S4 is: corroding the remaining aluminum metal mask with an aluminum corrosion solution, wherein the aluminum corrosion solution is dilute hydrochloric acid, phosphoric acid or dilute tetramethylammonium hydroxide.

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