Optical waveguide female die and processing method

Abstract

The invention provides an optical waveguide female die and a processing method, and the processing method comprises the steps: enabling a to-be-processed surface of a female die substrate to be covered with photoresist, and obtaining a first middle female die with a photoresist layer and the female die substrate; performing photoetching operation on the photoresist layer of the first middle female die to obtain a second middle female die with a hollow area in the photoresist layer; the position and the size of the hollow area are matched with the design position and the design size of the grating to be processed; performing tackifying evaporation on the second intermediate female mold, and coating the second intermediate female mold subjected to tackifying evaporation to obtain a third intermediate female mold with a female mold substrate, a photoresist layer and a coating layer; performing etching operation on the photoresist layer of the third middle female die to obtain an optical waveguide female die with surface embossment; the surface embossment is composed of the residual part of the coating layer after the etching operation. The method can simplify the processing technology of the optical waveguide female die and reduce the cost.

Description

Technical Field

[0001] This invention relates to the field of optical waveguide technology, and more specifically, to an optical waveguide master mold and its fabrication method. Background Technology

[0002] An optical waveguide is an optical structure that guides light propagation in a medium using the principle of total internal reflection. It is widely used in optical communication, augmented reality displays, and optical sensing. In diffraction grating-based optical waveguide devices, a precise grating structure is typically formed inside or on the surface of the waveguide to achieve functions such as light coupling, coupling out, or wavelength selection. Because the performance of an optical waveguide is highly dependent on the morphological accuracy and consistency of the grating, a master waveguide mold is often used for replication in mass production.

[0003] Optical waveguide master molds are mainly manufactured through a series of complex processes such as film deposition, photolithography, and dry etching. Due to the complexity of the manufacturing process and the high cost of equipment, the preparation cost of the master mold is very expensive. Furthermore, the complexity of the manufacturing process also leads to a decrease in the yield of the master mold, further increasing its manufacturing cost. Summary of the Invention

[0004] This application provides an optical waveguide master mold and a processing method to reduce the manufacturing cost and processing complexity of the optical waveguide master mold.

[0005] Firstly, a method for fabricating an optical waveguide master mold is provided, including:

[0006] Photoresist is applied to the surface to be processed on the master mold substrate to obtain a first intermediate master mold with a photoresist layer and a master mold substrate.

[0007] Photolithography is performed on the photoresist layer of the first intermediate master mold to obtain a second intermediate master mold with a hollowed-out area in the photoresist layer; the position and size of the hollowed-out area are matched with the design position and design size of the grating to be processed.

[0008] The second intermediate master mold is subjected to an adhesion-enhancing vapor deposition operation, and the second intermediate master mold after adhesion-enhancing vapor deposition is coated to obtain a third intermediate master mold having a master mold substrate, a photoresist layer and a coating layer.

[0009] The photoresist layer of the third intermediate master mold is etched to obtain an optical waveguide master mold with surface relief; the surface relief is composed of the remaining part of the coating layer after the etching operation.

[0010] In the above technical solution, by performing an adhesion-enhancing vapor deposition operation on the second intermediate master mold, the coating layer is connected to the master mold substrate in the hollow area using the adhesion-enhancing vapor deposition operation, thereby avoiding the use of dry etching, simplifying the processing flow of the optical waveguide master mold, and reducing processing costs.

[0011] In one possible implementation, the viscosity-enhancing vapor deposition operation includes:

[0012] The adhesive material is vapor-deposited onto the second intermediate master mold, and then the adhesive material is subjected to plasma activation treatment.

[0013] In one possible implementation, the plasma activation treatment is performed simultaneously with the vapor deposition process, or after the vapor deposition process is completed.

[0014] In one possible implementation, the plasma activation process includes:

[0015] An activation gas is introduced into the vapor deposition chamber, and the plasma source of the vapor deposition chamber is activated to ionize the activation gas, thereby activating the adhesion-enhancing material.

[0016] In one possible implementation, the activating gas includes at least one of the following: oxygen, argon, and nitrogen.

[0017] In one possible implementation, the plasma source includes a radio frequency plasma source or a DC glow discharge plasma source.

[0018] In one possible implementation, the coating process on the second intermediate master mold after viscosity-enhancing vapor deposition includes:

[0019] Based on the design dimensions of the grating to be processed, the coating rate and coating time of the coating equipment are determined; and the second intermediate master mold after viscosity-enhancing vapor deposition is placed in the coating equipment.

[0020] Based on the coating rate and coating time, the second intermediate master mold after the thickening vapor deposition is coated with a coating material.

[0021] In one possible implementation, the substrate of the master mold is made of a different material than the coating material.

[0022] In one possible implementation, the photolithography operation includes:

[0023] The photoresist layer is subjected to structural exposure using photolithography equipment; the exposed area of ​​the structural exposure matches the design position and design size of the grating to be processed.

[0024] The first intermediate master mold after structural exposure is developed to dissolve the photoresist in the exposed area, thereby obtaining the second intermediate master mold.

[0025] In one possible implementation, developing the first intermediate master mold after structural exposure includes:

[0026] The first intermediate master mold after exposure of the structure is placed on a spin coater; and, based on the design position and design size of the grating to be processed, the development time and developer flow rate of the spin coater are determined.

[0027] Based on the development time and the developer flow rate, the spin coater is controlled to spray developer to develop the first intermediate master mold after the structure has been exposed.

[0028] Secondly, an optical waveguide master mold is provided, wherein the optical waveguide master mold is prepared by any one of the optical waveguide master mold processing methods described in the present invention.

[0029] In the above technical solution, by performing an adhesion-enhancing vapor deposition operation on the second intermediate master mold, the coating layer is connected to the master mold substrate in the hollow area using the adhesion-enhancing vapor deposition operation, thereby avoiding the use of dry etching, simplifying the processing flow of the optical waveguide master mold, and reducing processing costs. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. These drawings are incorporated in and constitute a part of this specification. They illustrate embodiments conforming to the present invention and, together with the specification, serve to explain the technical solutions of the present invention. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 A flowchart of the optical waveguide master mold processing method provided in an embodiment of this application is shown;

[0032] Figure 2 A schematic diagram of the first intermediate master mold provided in an embodiment of this application is shown;

[0033] Figure 3 A top view of the second intermediate master mold provided in an embodiment of this application is shown;

[0034] Figure 4 A cross-sectional view of the second intermediate master mold provided in an embodiment of this application is shown;

[0035] Figure 5 A cross-sectional view of the third intermediate master mold provided in an embodiment of this application is shown;

[0036] Figure 6 A schematic diagram of an optical waveguide master mode provided in an embodiment of this application is shown. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the application will now be described in further detail with reference to the accompanying drawings.

[0038] It should be noted that, unless otherwise defined, the technical or scientific terms used in one or more embodiments of this specification should have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms "first," "second," and similar words used in one or more embodiments of this specification do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0039] To facilitate understanding of the optical waveguide master mold fabrication method provided in this application embodiment, its application scenario is first described. The optical waveguide master mold fabrication method provided in this embodiment is used to fabricate optical waveguide master molds. These master molds are molds used to replicate optical waveguide structures and typically have a structural shape opposite to the target optical waveguide. They are used to mass-produce micro / nano optical waveguide arrays made of materials such as polymers or glass. Optical waveguides are channels used to transmit optical signals in microstructures, confining light beams along a specific path and transmitting them with low loss. They are commonly found in fields such as optical communication, integrated photonic chips, sensors, and optical interconnects, such as augmented reality and mixed reality display devices.

[0040] Current methods for fabricating optical waveguide master molds involve a series of complex processes such as coating, photolithography, and dry etching. Due to the cumbersome processing and high equipment costs, the preparation cost of the master mold is extremely high. Furthermore, the complexity of the processing also leads to a decrease in the yield rate of the master mold, further increasing the processing cost.

[0041] Therefore, this application provides a method for fabricating an optical waveguide master mold to reduce the fabrication cost and the complexity of the fabrication process.

[0042] refer to Figure 1 As shown, Figure 1 A flowchart illustrating the optical waveguide master mold fabrication method provided in this application embodiment is shown. The optical waveguide master mold fabrication method provided in this application embodiment specifically includes the following steps:

[0043] Step 001: Cover the surface to be processed with photoresist onto the master mold substrate to obtain a first intermediate master mold with a photoresist layer and a master mold substrate.

[0044] The aforementioned photoresist is a photosensitive material used in semiconductor and micro / nano fabrication to transfer optical patterns onto a substrate. It can be processed through etching, deposition, or electroplating to form the desired three-dimensional pattern.

[0045] The aforementioned master mold substrate can be a clean, uncontaminated silicon wafer, used as the substrate for the substrate optical waveguide master mold. One side of the master mold substrate can be selected as the surface to be processed, and the grating structure can be processed on this surface.

[0046] Specifically, a spin coater can be used to coat the surface of the master mold substrate with photoresist. When using a spin coater, the parameters of the spin coater can be adjusted according to the required thickness of the photoresist, such as the coating thickness, acceleration, and rotation time, to ensure the coating thickness and uniformity.

[0047] For example, a spin coater can provide a rotatable stage on which a master mold substrate can be placed. Above the stage are pipes and nozzles, through which materials such as photoresist and developer can be sprayed from the nozzles and fall onto the master mold substrate.

[0048] The required thickness of the photoresist can be set according to the design dimensions of the grating to be processed. For example, if the design dimensions of the grating to be processed include the height of the grating structure, then the required thickness can be set to the height of the grating structure.

[0049] like Figure 2 The diagram shown is a schematic representation of the first intermediate master mold provided in an embodiment of this application. In the first intermediate master mold, the photoresist layer 20 is located on the upper layer of the master mold substrate 10.

[0050] Step 002: Perform photolithography on the photoresist layer of the first intermediate master mold to obtain a second intermediate master mold with a hollow area in the photoresist layer; the position and size of the hollow area match the design position and design size of the grating to be processed.

[0051] Specifically, photolithography can be performed on the photoresist layer of the first intermediate master mold to remove photoresist at specific locations, forming hollow areas (i.e., groove areas). This creates a grating structure within the photoresist layer, with the hollow areas representing the gaps between the grating structures. The hollow areas can have the same structure as the grating to be processed, and the grating structure is subsequently formed within these hollow areas. The grating to be processed refers to the grating structure to be fabricated on the optical waveguide master mold, having pre-designed positions and dimensions.

[0052] In one possible implementation, the photolithography operation may include:

[0053] The photoresist layer is structurally exposed using a photolithography device; the exposed area of ​​the structural exposure matches the design position and design size of the grating to be processed; the first intermediate master mold after structural exposure is developed to dissolve the photoresist in the exposed area, thereby obtaining the second intermediate master mold.

[0054] Photolithography equipment refers to precision manufacturing equipment commonly used in semiconductor manufacturing, micro-nano fabrication, and optical waveguide fabrication. It is used to transfer fine patterns onto the surface of a substrate coated with photoresist. It is one of the core pieces of equipment in the production of chips, microstructures, and optical devices.

[0055] For example, the lithography equipment can be an electron beam lithography (EBL) equipment or a deep ultraviolet lithography (DUV) equipment. Electron beam lithography is a micro / nano fabrication technique that uses a focused electron beam to directly "write" patterns onto the surface of photoresist, eliminating the need for a mask as in traditional lithography. Deep ultraviolet lithography is a lithography technique that uses a deep ultraviolet light source (wavelength approximately 193nm or 248nm) for pattern transfer. It uses deep ultraviolet light to project micron- or even submicron-scale patterns onto the surface of a wafer coated with photoresist through a mask, followed by development and etching to complete the pattern transfer.

[0056] When a photoresist layer is exposed using a photolithography device, the incident electron beam particles break the polymer chains of the photoresist, making the photoresist in the exposed area easier to dissolve and thus more readily dissolved during the development process.

[0057] The development process can employ a dynamic development method. During development, the first intermediate master mold after structural exposure is placed on a spin coater, with the stage rotating at low speed. Simultaneously, the spin coater uses centrifugal force to spray the developer onto the photoresist layer, dissolving the photoresist in the exposed areas. The development effect can be adjusted by controlling the development time and developer flow rate.

[0058] In one possible implementation, the first intermediate master mold after the structure has been exposed can be placed on a spin coater; and the development time and developer flow rate of the spin coater can be determined based on the design position and design size of the grating to be processed; then, based on the development time and developer flow rate, the spin coater can be controlled to spray developer to develop the first intermediate master mold after the structure has been exposed.

[0059] like Figure 3 and Figure 4 The figures shown are a top view and a cross-sectional view of the second intermediate master mold provided in the embodiments of this application, respectively. Figure 3 and Figure 4The grating structure region 21 may include a grating protrusion region 211 and a grating groove region 212.

[0060] Step 003: Perform an adhesion-enhancing vapor deposition operation on the second intermediate master mold, and then coat the second intermediate master mold after adhesion-enhancing vapor deposition to obtain a third intermediate master mold having a master mold substrate, a photoresist layer, and a coating layer.

[0061] In the third intermediate master mold, the grating structure formed by the coating material in the hollowed-out position of the photoresist layer is connected to the master mold substrate.

[0062] In this step, the second intermediate master mold can first be subjected to an adhesion-enhancing vapor deposition operation, whereby the adhesion-enhancing material is vapor deposited onto the second intermediate master mold, and then a coating is applied so that the coating material used for coating can be connected to the second intermediate master mold. The coating material is then deposited onto the surface of the second intermediate master mold to form the third intermediate master mold.

[0063] like Figure 5 The image shown is a cross-sectional view of the third intermediate master mold provided in an embodiment of this application. Figure 5 In the middle, the third intermediate master mold includes a master mold base 10, a photoresist layer 20, and a coating layer 30.

[0064] The aforementioned viscosity-enhancing vapor deposition process can improve the adhesion between the coating material and the master mold substrate. Furthermore, during the viscosity-enhancing vapor deposition process, the viscosity-enhancing material can be subjected to plasma activation treatment to further increase its viscosity and improve adhesion.

[0065] In one possible implementation, plasma activation treatment can be performed simultaneously with the vapor deposition process, or it can be performed after the vapor deposition process is completed.

[0066] When plasma activation treatment is performed simultaneously with the vapor deposition process, the surface can be activated instantly during the deposition of the vapor-deposited film, resulting in high efficiency. When plasma activation treatment is performed after the vapor deposition process, it can improve the surface adhesion of the second intermediate master mold after vapor deposition.

[0067] For example, vapor deposition can be performed using vapor deposition equipment (such as a vacuum vapor deposition chamber). The vapor deposition equipment has vapor deposition walls, and a plasma source (such as a radio frequency plasma source or a DC glow discharge plasma source) can be placed within the vapor deposition chamber. Specifically, a second intermediate master mold can be placed into the chamber of the vapor deposition equipment, and the chamber can be evacuated to avoid interference from air molecules. Then, the evaporation of the adhesion-enhancing material (such as chromium (Cr), titanium (Ti), silicon dioxide (SiO2), etc.) can begin, depositing it on the surface of the photoresist layer and the master mold substrate. During plasma activation, the plasma source can be turned on, a small amount of activating gas (such as oxygen, argon, nitrogen, etc.) can be introduced, and the process can be initiated to ionize the gas into plasma. The high-energy ions and active free radicals in the plasma bombard the surface of the newly deposited film, removing organic residues, breaking surface molecular chains, and forming active groups (such as hydroxyl, amino groups, etc.), enhancing the chemical bonding with subsequent coatings.

[0068] When coating the second intermediate master mold after viscosity-enhancing vapor deposition, the required coating thickness can be determined based on the design dimensions of the grating to be processed (such as the height of the grating), and the coating rate and coating time of the coating equipment can be determined based on the coating thickness; then, the second intermediate master mold after viscosity-enhancing vapor deposition is placed in the coating equipment. Afterwards, the second intermediate master mold after viscosity-enhancing vapor deposition can be coated with the coating material according to the determined coating rate and coating time.

[0069] In one possible implementation, the substrate of the master mold and the coating material can be made of different materials to achieve different etching ratios and improve the accuracy of the process.

[0070] Step 004: Etch the photoresist layer of the third intermediate master mold to obtain an optical waveguide master mold with surface relief; the surface relief is composed of the remaining part of the coating layer after the etching operation.

[0071] In this step, the photoresist in the photoresist layer can be etched away by an etching operation. After the photoresist is removed, the coating layer attached to the photoresist will fall off along with the photoresist, while the coating layer bonded to the master mold substrate will not fall off, thus forming a waveguide master mold with surface relief.

[0072] like Figure 6 The diagram shown is a schematic of an optical waveguide master mold provided in an embodiment of this application. The optical waveguide master mold includes a master mold substrate 10 and a surface relief 40, which is composed of the remaining portion of the coating layer, forming a grating structure.

[0073] Specifically, the etching operation can use oxygen ion etching to remove the photoresist.

[0074] In the above technical solution, by performing an adhesion-enhancing vapor deposition operation on the second intermediate master mold, the coating layer is connected to the master mold substrate in the hollow area using the adhesion-enhancing vapor deposition operation, thereby avoiding the use of dry etching, simplifying the processing flow of the optical waveguide master mold, and reducing processing costs.

[0075] This application also provides an optical waveguide master mold, which is an optical waveguide master mold prepared using any of the above-described optical waveguide master mold processing methods.

[0076] In the above technical solution, the master mold substrate and the grating structure of the optical waveguide master mold are connected together by adhesive vapor deposition, eliminating the need for complex processing techniques such as dry etching, thus greatly reducing the processing difficulty of the optical waveguide master mold. Furthermore, plasma can be used to activate the adhesive material during the adhesive vapor deposition process, which can effectively improve the connection strength between the master mold substrate and the grating structure, thereby improving the durability of the optical waveguide master mold.

[0077] This application also provides an optical waveguide, which is fabricated using the aforementioned optical waveguide master mold. As can be seen from the aforementioned optical waveguide master mold, the master mold has high durability, the grating structure is not easily detached from the master mold substrate, and the optical waveguide fabricated using the aforementioned optical waveguide master mold has higher precision and a higher yield.

[0078] One or more embodiments of this specification are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments of this specification should be included within the scope of protection of this disclosure.

[0079] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for fabricating an optical waveguide master mold, characterized in that, include; Photoresist is applied to the surface of the master mold substrate to be processed, resulting in a first intermediate master mold having a photoresist layer and a master mold substrate. Photolithography is performed on the photoresist layer of the first intermediate master mold to obtain a second intermediate master mold with a hollowed-out area in the photoresist layer; the position and size of the hollowed-out area are matched with the design position and design size of the grating to be processed. The second intermediate master mold is subjected to an adhesion-enhancing vapor deposition operation, and the second intermediate master mold after adhesion-enhancing vapor deposition is coated to obtain a third intermediate master mold having a master mold substrate, a photoresist layer and a coating layer. The photoresist layer of the third intermediate master mold is etched to obtain an optical waveguide master mold with surface relief; the surface relief is composed of the remaining part of the coating layer after the etching operation.

2. The method according to claim 1, characterized in that, The viscosity-enhancing vapor deposition operation includes: The adhesive material is vapor-deposited onto the second intermediate master mold, and then the adhesive material is subjected to plasma activation treatment.

3. The method according to claim 2, characterized in that, The plasma activation treatment is performed simultaneously with the vapor deposition process, or after the vapor deposition process is completed.

4. The method according to claim 2, characterized in that, The plasma activation process includes: An activation gas is introduced into the vapor deposition chamber, and the plasma source of the vapor deposition chamber is activated to ionize the activation gas, thereby activating the adhesion-enhancing material.

5. The method according to claim 4, characterized in that, The plasma source includes a radio frequency plasma source or a DC glow discharge plasma source.

6. The method according to claim 1, characterized in that, The coating process for the second intermediate master mold after viscosity-enhancing vapor deposition includes: Based on the design dimensions of the grating to be processed, the coating rate and coating time of the coating equipment are determined; and the second intermediate master mold after viscosity-enhancing vapor deposition is placed in the coating equipment. Based on the coating rate and coating time, the second intermediate master mold after the thickening vapor deposition is coated with a coating material.

7. The method according to claim 6, characterized in that, The substrate of the master mold is made of a different material than the coating material.

8. The method according to claim 1, characterized in that, The photolithography operation includes: The photoresist layer is subjected to structural exposure using photolithography equipment; the exposed area of ​​the structural exposure matches the design position and design size of the grating to be processed. The first intermediate master mold after structural exposure is developed to dissolve the photoresist in the exposed area, thereby obtaining the second intermediate master mold.

9. The method according to claim 8, characterized in that, The development of the first intermediate master mold after structural exposure includes: The first intermediate master mold after exposure of the structure is placed on a spin coater; and, based on the design position and design size of the grating to be processed, the development time and developer flow rate of the spin coater are determined. Based on the development time and the developer flow rate, the spin coater is controlled to spray developer to develop the first intermediate master mold after the structure has been exposed.

10. An optical waveguide master mode, characterized in that, The optical waveguide master mold is an optical waveguide master mold prepared using the optical waveguide master mold processing method as described in any one of claims 1 to 9.

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