A method for manufacturing a diamond-based thin film circuit and a circuit thereof

Abstract

The present application belongs to the technical field of diamond-based thin film circuit, and particularly relates to a diamond-based thin film circuit manufacturing method and the circuit. The method comprises the following steps: selecting a bottom silicon material; manufacturing a diamond film above the bottom silicon material; cleaning the upper surface of the diamond film; plating a film on the upper surface of the diamond film to form a film layer, and the upper surface of the film layer is a gold layer; coating a photoresist on the upper surface of the film layer and performing a pre-baking treatment; using a UV exposure machine and a corresponding mask to process the photoresist to form a process window; electroplating gold on the process window to form a thin film circuit pattern, and plating a protective layer on the upper surface of the thin film circuit pattern; removing the photoresist; removing the protective layer; according to the circuit shape, performing a slotting treatment to form a shape processing slot; injecting a silicon etching solution into the shape processing slot to remove the bottom silicon material; and cleaning to obtain the diamond-based thin film circuit. The silicon material is used as a support body to avoid the phenomenon of fragments in the processing process.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of diamond-based thin film circuit, and particularly relates to a diamond-based thin film circuit manufacturing method and the circuit. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] Diamond has the highest thermal conductivity among all materials, plus its high resistivity and high breakdown field strength, so diamond film can be used as the substrate or insulating layer of integrated circuits and the heat-conducting insulating layer of solid-state lasers. It has been applied to microwave, millimeter wave and terahertz wave devices and integrated circuits, which can solve the heat dissipation problem of high-drive-power diodes, avoid the failure of diodes due to temperature rise, and expand its application field. The characteristics of diamond film itself, the small thickness and slender shape of the diamond-based thin film circuit are the main reasons for the slow popularization of this application.

[0004] At present, the diamond-based thin film circuit generally adopts the traditional manufacturing method, that is, through ten processes and dozens of steps such as substrate processing, cleaning, vacuum coating, photoetching circuit pattern, electroplating, and shape processing. The whole manufacturing process is very long. Temporary bonding and debonding technology can be used in the process to provide support for the diamond film and prevent it from breaking to some extent, but the breaking probability is very high during temporary bonding and debonding, which cannot well solve the problem of manufacturing difficulty. The processing of diamond film includes the growth, thinning, rough grinding, and fine polishing of diamond film layer; cleaning is to remove organic or inorganic pollution on the surface of diamond film to improve the surface activity and prepare for subsequent coating; vacuum coating is to make the required film layer on the surface of diamond film by vacuum sputtering, evaporation, etc.; photoetching is to transfer the circuit pattern to the photoresist coated on the surface of diamond film by exposure and development, form a corrosion window, and then use wet or dry etching technology to remove the unnecessary film layer to obtain the circuit pattern; electroplating is a method to thicken the circuit pattern to reduce the on-resistance; for the high-hardness substrate of diamond, shape processing is generally carried out by laser processing. Through the above super-long manufacturing process, the required circuit is obtained.

[0005] With the increase of the use frequency, the thickness of diamond film needs to be gradually reduced into the terahertz wave field, and the thickness of diamond film needs to be less than 50 microns, and the aspect ratio of the circuit shape is greater than 5:1, and in some cases it will be higher than 10:1. These requirements make the diamond film circuit extremely easy to break during manufacturing, and the micron-level shape size precision is out of the question, so the manufacturing difficulty and cost are very high, and the yield is low. SUMMARY

[0006] The present application discloses a diamond-based thin film circuit manufacturing method and a circuit thereof.

[0007] According to some embodiments, the present application adopts the following technical solutions:

[0008] In a first aspect, the present application provides a diamond-based thin film circuit manufacturing method.

[0009] A diamond-based thin film circuit manufacturing method comprises the following steps:

[0010] (1) selecting a bottom silicon material;

[0011] (2) manufacturing a diamond film above the bottom silicon material;

[0012] (3) cleaning the upper surface of the diamond film;

[0013] (4) coating a film layer on the upper surface of the diamond film, and the upper surface of the film layer is a gold layer;

[0014] (5) coating a photoresist on the upper surface of the film layer and performing a pre-baking treatment;

[0015] (6) using an ultraviolet exposure machine to process the photoresist using a corresponding mask to form a process window;

[0016] (7) electroplating gold on the process window to form a thin film circuit pattern, and coating a protective layer on the upper surface of the thin film circuit pattern;

[0017] (8) removing the photoresist;

[0018] (9) removing the film layer not protected by the protective layer, and then removing the protective layer;

[0019] (10) performing slotting processing according to the circuit shape to form a shape processing slot;

[0020] (11) injecting a silicon etching solution into the shape processing slot to remove the bottom silicon material;

[0021] (12) cleaning to obtain a diamond-based thin film circuit.

[0022] Further, the step (2) specifically comprises cleaning the upper surface of the diamond film by a cleaning process including chromium acid solution immersion, DI water ultrasonic cleaning, centrifugal spin-drying, and baking.

[0023] Further, the film layer comprises an adhesion layer and a conductive layer from bottom to top.

[0024] Further, the film layer comprises, from bottom to top, a resistance layer, an adhesion layer and a conductive layer.

[0025] Further, the step (5) specifically comprises: using an ultraviolet exposure machine, using a corresponding mask to perform exposure, development and film hardening treatment on the coated photoresist, to form a process window for gold plating.

[0026] Further, in the step (9), the protective layer is removed by using an etching liquid.

[0027] Further, the width of the profile processing groove should be not less than the thickness of the diamond film, and the depth of the profile processing groove is greater than the thickness of the diamond film.

[0028] Further, the step (10) comprises compensating the processing track of the profile processing groove.

[0029] Further, in the step (11), the bottom layer silicon material is removed by using a silicon etching liquid.

[0030] Further, the step (12) specifically comprises: performing DI water flushing, DI water ultrasonic cleaning and acetone dehydration treatment in sequence, to obtain the diamond-based thin film circuit.

[0031] In a second aspect, the present application provides a diamond-based thin film circuit.

[0032] A diamond-based thin film circuit is made by the diamond-based thin film circuit manufacturing method of the first aspect, comprising: a diamond film, a film layer and a thin film circuit pattern connected in sequence from bottom to top.

[0033] Compared with the prior art, the present application has the following beneficial effects:

[0034] (1) The present application proposes a diamond-based thin film circuit manufacturing method, which uses silicon-based diamond film as a substrate for circuit manufacturing. After the circuit pattern is manufactured, a profile processing groove is manufactured along the circuit profile by using laser processing technology, and then the silicon material under the diamond film is etched by using an etching liquid through the profile processing groove, to obtain a diamond-based thin film circuit meeting the requirements. In the process, the silicon material is used as a support body, which can improve the overall strength of the substrate, effectively avoid the fragmentation phenomenon in the process, and reduce the manufacturing difficulty. In addition, when the profile is processed by laser, the silicon material at the bottom of the diamond film not only has a supporting effect, but also is a heat transfer channel. Compared with the diamond film without a support body, the heat generated during laser processing can be relatively timely conducted to the workbench, avoiding the fracture of the diamond film caused by local overheating.

[0035] (2) The application proposes a method for removing the bottom silicon material, which adopts the method of slotting nearby, the slotting is defined as the profile processing slot, and the width and depth of the profile processing slot are required to be greater than or not less than the thickness of the diamond film, so that the silicon material etching liquid can exert the etching effect nearby, compared with the method of completely etching the entire back silicon material to obtain the required circuit, the scheme of the application can more efficiently remove the bottom silicon material, and also reduces the risk of the diamond-based thin film circuit caused by long-term soaking in the etching liquid.

[0036] (3) The profile processing method proposed by the application can effectively guarantee the accuracy of the profile of the diamond-based thin film circuit, and the method of process compensation according to the laser spot is proposed, and the process compensation amount is fine-tuned through actual measurement data in the process to meet the requirement of higher accuracy.

[0037] (4) The application proposes a method of increasing a protective layer metal after electroplating gold, which can effectively avoid the damage to the thin film circuit pattern during the removal of the bottom silicon material of the diamond film.

[0038] (5) The method of using the etching liquid with high etching selectivity in the patent is used to remove the bottom silicon material and the protective layer metal, which is a necessary condition for the success of the circuit manufacturing method. BRIEF DESCRIPTION OF DRAWINGS

[0039] The drawings accompanying the specification of the application form part of the application and serve to further understand the application, the illustrative embodiments of the application and the description thereof serve to explain the application and do not constitute an improper limitation of the application.

[0040] Figure 1 is a schematic diagram of a diamond substrate thin film circuit structure shown in the embodiment of the application;

[0041] Figure 2 is a schematic diagram of a unit circuit array shown in the embodiment of the application;

[0042] Figure 3 is a schematic diagram of a diamond substrate shown in the embodiment of the application;

[0043] Figure 4 is a schematic diagram of the diamond substrate after cleaning shown in the embodiment of the application;

[0044] Figure 5 is a schematic diagram of the film formation shown in the embodiment of the application;

[0045] Figure 6 is a schematic diagram of the application of photoresist shown in the embodiment of the application;

[0046] Figure 7is a schematic view after exposure, development and other processing according to an embodiment of the present application;

[0047] Figure 8 is a schematic view after gold plating according to an embodiment of the present application;

[0048] Figure 9 is a schematic view after removal of photoresist according to an embodiment of the present application;

[0049] Figure 10 is a schematic view after etching of the gold layer according to an embodiment of the present application;

[0050] Figure 11 is a schematic view after laser slotting according to an embodiment of the present application;

[0051] Figure 12 is a schematic view after removal of the underlying silicon material according to an embodiment of the present application;

[0052] Figure 13 is a flow chart of a method for manufacturing a diamond-based thin film circuit according to an embodiment of the present application;

[0053] In the figure, 1-1 is the underlying silicon material, 1 is the diamond film, 2 is the thin film circuit pattern, 3 is the film layer, 4 is the photoresist, 5 is the process window, 6 is the protective layer, 7 is the circuit outline, 8 is the outline processing slot, and 9 is the etching cavity. DETAILED DESCRIPTION

[0054] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0055] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0056] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0057] In the present application, the terms such as "upper", "lower", "bottom", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only a relationship word determined for the purpose of describing the structural relationship of the components or elements of the present application, and cannot be understood as a limitation of the present application.

[0058] In the present application, terms such as "connection" should be understood broadly, which means fixed connection, integral connection or detachable connection; direct connection or indirect connection through intermediate medium. For relevant researchers or technicians in the field, the specific meaning of the above terms in the present application can be determined according to the specific circumstances, and should not be understood as a limitation on the present application.

[0059] Embodiment one

[0060] The present embodiment provides a diamond-based thin film circuit manufacturing method.

[0061] The diamond-based thin film circuit has a structure as shown in Figure 1 The diamond-based thin film circuit has a structure as shown in

[0062] The present embodiment takes the diamond-based thin film circuit manufacturing method as shown in Figure 1 In order to efficiently manufacture the required circuit, a large-size substrate is generally used to manufacture a unit circuit pattern array (as shown in Figure 2 The present embodiment takes the diamond-based thin film circuit manufacturing method as shown in

[0063] As shown in Figure 13 The flow of the diamond-based thin film circuit manufacturing method of the present embodiment is as follows:

[0064] (1) Substrate manufacturing

[0065] The present embodiment uses silicon-based diamond as the manufacturing material. The simple manufacturing principle is to grow and manufacture diamond film 1 on the silicon material by using chemical vapor deposition method. The thickness and accuracy of the diamond film 1 need to be determined according to the circuit design requirements. Generally, the thickness of the silicon material 1-1 below the diamond film 1 is required to be more than 5 times the thickness of the diamond film to improve the overall strength and avoid fragmentation during the manufacturing process, as shown in Figure 3

[0066] (2) Cleaning

[0067] It needs to go through cleaning processes such as chromium acid solution immersion, DI water ultrasonic cleaning, centrifugal drying and baking in sequence to improve the activity of the diamond surface and prepare for vacuum coating, as shown in Figure 4

[0068] (3) Vacuum coating ​​

[0069] Traditional methods are used to deposit a gold coating onto the surface of a diamond film to create film layer 3. Depending on the circuit design and manufacturing process, film layer 3 may include a resistive layer, an adhesion layer, and a conductive layer. In this technical solution, from bottom to top, it includes an adhesion layer (TiW) and a conductive layer (Au). If necessary, a resistive layer (such as TaN) can be added below the adhesion layer. Figure 5 As shown.

[0070] (4) Coating with photoresist

[0071] Photoresist 4 is coated onto the surface of the diamond film and pre-baking is performed, such as... Figure 6 As shown.

[0072] (5) Exposure and development

[0073] Using an ultraviolet exposure machine and a corresponding mask, the coated photoresist is exposed, developed, and hardened to form the electroplating gold process window 5, such as... Figure 7 As shown.

[0074] (6) Gold plating

[0075] Electroplating gold forms the thin-film circuit pattern 2. Generally, the gold plating layer thickness is required to be between 3 and 4 micrometers. After gold plating, a protective layer 6 needs to be plated. This protective layer is used when the outer film layer 3 of the thin-film circuit pattern 2 is etched away in a later process. In this embodiment, a nickel layer with a thickness of not less than 5 micrometers is generally electroplated as the protective layer. Figure 8 As shown.

[0076] (7) Remove photoresist

[0077] Remove photoresist, such as Figure 9 As shown.

[0078] (8) Corrosion of the unprotected film layer 3. Removal of the protective layer

[0079] Etching removes the film layer 3 outside the thin-film circuit pattern 2 and the protective layer 6. Many types of etching solutions are used, but those with high selectivity are necessary. For example, in this embodiment, the protective layer 6 is made of nickel, and the etching solution used is a 40%–60% ferric chloride aqueous solution. Figure 10 As shown.

[0080] (9) Laser grooving

[0081] like Figure 11As shown, the groove processing is performed along the circuit profile 7 by an infrared laser processing machine. The groove surrounds the circuit profile 7 in a ring shape, and the groove is referred to as a profile processing groove 8. The purpose of the profile processing groove is to define the profile of the diamond-based thin film circuit and to remove the underlying silicon material. In order to ensure the profile size accuracy, the processing track needs to be compensated, for example, when the laser spot is 0.005 mm, the processing track needs to be moved outward by 0.005 mm as a whole. In addition, the width of the profile processing groove 8 should be not less than the thickness of the diamond film 1, and the depth should be greater than the thickness of the diamond film, so as to efficiently remove the underlying silicon material 1-1. However, the depth should not penetrate the underlying silicon material 1-1, so that the diamond-based thin film circuit can maintain a good array formation before the underlying silicon material 1-1 is removed, and the effect of removing the underlying silicon material and the collection of the unit circuits after the underlying silicon material is removed can be observed at any time.

[0082] In this embodiment, the laser spot is about 0.008 mm, the average power of the selected laser is 5 W to 7 W, the laser pulse repetition frequency is 20,000 Hz to 30,000 Hz, the workbench running speed is 50 mm / sec to 70 mm / sec, the groove is processed by gradually expanding the processing track, each track is processed 80 times, the expansion feed amount is 0.008 mm / time, and the expansion times are not less than 5 times. As a process compensation for the profile size processing, the first track from the inside to the outside is moved outward by 0.008 mm relative to the circuit profile 7. For a higher requirement, the process compensation amount needs to be fine-tuned by actually measuring the offset amount in the process.

[0083] (10) Removing the silicon material

[0084] The silicon etching liquid is used to remove the underlying silicon material 1-1. The etching liquid with a high etching selectivity relative to each component of the diamond-based thin film circuit (including each component in the film layer 3) is selected. In this embodiment, a 20% to 50% concentration of potassium hydroxide aqueous solution is selected as the etching liquid. The etching progress needs to be observed under a microscope at any time, and the etching time is appropriately increased to completely etch the residual silicon material on the back of the diamond-based thin film circuit, so as to finally form an etching cavity 9, as shown. Figure 12 It should be noted that Figure 12 The drawings shown are not schematic diagrams during and after etching, but are only used to illustrate that the lower part of the diamond-based thin film circuit is gradually etched after etching.

[0085] (11) Cleaning

[0086] After the etching is completed, each unit circuit is carefully taken out and placed in a new container. The diamond-based thin film circuit is completed after DI water flushing, DI water ultrasonic cleaning, and acetone dehydration treatment.

[0087] The embodiment proposes a new manufacturing method, adopts silicon-based diamond film as a substrate, and uses silicon material as a support during the manufacturing process, so that the fragmentation phenomenon during operation, circulation and laser processing can be completely avoided, after the thin film circuit pattern is manufactured, the groove processing is performed along the circuit shape by using ultraviolet laser, the etching liquid can etch the silicon material at the bottom of the diamond film through the shape processing groove, so that the etching time is shortened and the influence of the etching liquid on the thin film circuit pattern is reduced; in addition, the process compensation method for the protective layer metal after the plating gold layer is added and the laser manufacturing shape processing groove plays an important role in meeting the requirements of the whole technical solution described in the embodiment. The method greatly reduces the manufacturing difficulty, guarantees the integrity of the diamond film during the manufacturing process, optimizes the circuit shape size manufacturing technology, and meets the demand of micron-level shape precision.

[0088] Embodiment two

[0089] The embodiment provides a diamond-based thin film circuit.

[0090] A diamond-based thin film circuit is manufactured by the diamond-based thin film circuit manufacturing method in embodiment one, and includes a diamond film, a film layer and a thin film circuit pattern connected in sequence from bottom to top.

[0091] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of fabricating a diamond-based thin-film circuit, comprising: The method comprises the following steps: (1) selecting a bottom silicon material; (2) making a diamond film above the bottom silicon material; (3) cleaning the upper surface of the diamond film; (4) coating a film layer on the upper surface of the diamond film, and the upper surface of the film layer is a gold layer; (5) coating a photoresist on the upper surface of the film layer and performing a pre-baking treatment, which specifically comprises: using a UV exposure machine and a corresponding mask to perform exposure, development and hardening treatment on the coated photoresist to form a gold plating process window; (6) using a UV exposure machine and a corresponding mask to process the photoresist to form a process window; (7) electroplating gold on the process window to form a thin film circuit pattern, and coating a protective layer on the upper surface of the thin film circuit pattern; (8) removing the photoresist; (9) removing the film layer not protected by the protective layer, and then removing the protective layer; (10) according to the circuit shape, performing slotting treatment to form a shape processing slot; (11) injecting a silicon etching solution into the shape processing slot to remove the bottom silicon material; (12) cleaning to obtain a diamond-based thin film circuit.

2. The diamond-based thin film circuit fabrication method according to claim 1, wherein The step (2) specifically comprises: performing cleaning treatment including chromium acid solution immersion, DI water ultrasonic cleaning, centrifugal spin-drying and baking on the upper surface of the diamond film.

3. The diamond-based thin film circuit fabrication method according to claim 1, wherein The film layer comprises an adhesion layer and a conductive layer from bottom to top; Or, the film layer comprises a resistance layer, an adhesion layer and a conductive layer from bottom to top.

4. The diamond-based thin film circuit fabrication method of claim 1, wherein, In the step (9), the protective layer is removed by using an etching solution.

5. The diamond-based thin film circuit fabrication method of claim 1, wherein, The width of the shape processing slot should be not less than the thickness of the diamond film, and the depth of the shape processing slot is greater than the thickness of the diamond film.

6. The diamond-based thin film circuit fabrication method of claim 1, wherein, In the step (10), the processing track of the shape processing slot is compensated.

7. The diamond-based thin film circuit fabrication method of claim 1, wherein, In the step (11), the bottom silicon material is removed by using a silicon etching solution.

8. The diamond-based thin film circuit fabrication method of claim 1, wherein, The step (12) specifically comprises: performing DI water rinsing, DI water ultrasonic cleaning and acetone dehydration treatment in sequence to obtain a diamond-based thin film circuit.

9. A diamond-based thin film circuit, characterized by, The diamond-based thin film circuit is made by the method of any one of claims 1-8, and comprises a diamond film, a film layer and a thin film circuit pattern connected in sequence from bottom to top.

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