Preparation method of waveguide device
By covering the waveguide structure with an organic protective layer and combining the organic protective layer with an isolation layer using a high etch selectivity, the problem of damage to the waveguide structure during the removal of the protective layer was solved, and high-quality and highly controllable waveguide device fabrication was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-12
- Publication Date
- 2026-03-13
AI Technical Summary
Existing technologies often damage the waveguide structure when removing the protective layer on top of it, resulting in poor process controllability and affecting the quality of the waveguide structure.
An organic protective layer is used to cover the waveguide structure. The high etch selectivity between the organic protective layer and the isolation layer protects the waveguide structure. Then, an ashing process is used to remove the organic protective layer to avoid damaging the waveguide structure.
It improves the quality and process controllability of waveguide structures, reduces the difficulty of fabricating waveguide devices, and avoids over-cutting and undercutting phenomena.
Smart Images
Figure CN121657205A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of waveguide device fabrication and relates to a method for fabricating waveguide devices. Background Technology
[0002] Silicon photonics devices consist of a device layer within a silicon-on-insulator (SOI) wafer. This wafer is separated from the substrate layer by a buried oxide layer. The device layer is etched to form a waveguide structure. Currently, in the fabrication of silicon photonics devices, the waveguide structure is typically etched into the device layer first, followed by the deposition of a hard mask layer to protect the waveguide across the entire wafer. Then, other structures required for the silicon photonics device are etched in areas outside the waveguide structure. After etching, a combination of dry and wet etching is used to remove the hard mask layer covering the waveguide structure. However, because wet etching has high selectivity and isotropic etching characteristics, while dry etching has poor selectivity and anisotropic etching characteristics, undercutting and over-etching are prone to occur when etching to the surface of the buried oxide layer. This results in poor process controllability, easily damages the waveguide structure, and affects the quality of the waveguide structure.
[0003] Therefore, there is an urgent need to find a method for fabricating waveguide devices that can avoid damaging the waveguide structure during the process of removing the protective layer on top of the waveguide structure. Summary of the Invention
[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for fabricating waveguide devices to solve the problem that the waveguide structure is easily damaged when removing the hard mask layer that protects the waveguide structure in the prior art.
[0005] To achieve the above and other related objectives, the present invention provides a method for fabricating a waveguide device, comprising the following steps:
[0006] A wafer with a device layer disposed on its upper surface is provided, the wafer comprising a first region and a second region;
[0007] A waveguide structure is formed in the device layer on the upper surface of the first region, and an organic protective layer is formed on the upper surface of the first region that at least covers the exposed surface of the waveguide structure.
[0008] An isolation layer is formed covering the exposed upper surface of the wafer and the exposed surface of the organic protective layer;
[0009] A microstructure is formed above the second region, and the isolation layer covering the organic protective layer is removed to expose the upper surface;
[0010] Remove the organic protective layer.
[0011] Optionally, the wafer further includes a substrate and a buried oxide layer stacked sequentially, with the device layer located on the upper surface of the buried oxide layer.
[0012] Optionally, forming the organic protective layer includes the following steps:
[0013] An organic protective material layer of a predetermined thickness is formed on the upper surface of the wafer after the waveguide structure is formed;
[0014] A patterned masking layer is formed on the upper surface of the organic protective material layer, and the organic protective material layer is etched based on the patterned masking layer to obtain an organic protective layer covering the exposed surface of the waveguide structure.
[0015] Optionally, the method for forming the organic protective material layer includes spin coating and chemical vapor deposition; the method for etching the organic protective material layer includes dry etching.
[0016] Optionally, the material of the organic protective layer includes, but is not limited to, at least one of photoresist, epoxy resin, PI, and PBO.
[0017] Optionally, the organic protective layer covers the exposed surface of the waveguide structure as well as the exposed upper surface of the first region.
[0018] Optionally, the material of the isolation layer includes silicon oxide.
[0019] Optionally, the microstructure is embedded in the isolation layer.
[0020] Optionally, the method for removing the isolation layer covering the organic protective layer and exposing the upper surface includes dry etching and wet etching.
[0021] Optionally, the method for removing the organic protective layer includes an ashing process.
[0022] As described above, the waveguide device fabrication method of the present invention improves the fabrication process of the waveguide device by first forming the waveguide structure in the device layer on the upper surface of the first region, and then protecting the waveguide structure with the organic protective layer. The organic protective layer is made of organic material to achieve a high etching selectivity between the organic protective layer and the isolation layer, while facilitating removal. Then, the microstructure is fabricated, the isolation layer above the waveguide structure is removed, and the organic protective layer is removed. Due to the protection of the organic protective layer, damage to the waveguide structure is avoided during the dry etching process of removing the isolation layer. The organic protective layer is then removed using an ashing process, which avoids damage to the waveguide structure during the removal of the organic protective layer, ensuring the quality of the waveguide structure, reducing the difficulty of fabricating the waveguide device, and providing high process controllability, thus possessing high industrial application value. Attached Figure Description
[0023] Figure 1The diagram shows a schematic of the fabrication process of the waveguide device of the present invention.
[0024] Figure 2 The diagram shows a cross-sectional structure of a wafer used in the fabrication method of the waveguide device of the present invention.
[0025] Figure 3 The diagram shown is a cross-sectional view of the waveguide structure after it has been formed, illustrating the fabrication method of the waveguide device of the present invention.
[0026] Figure 4 The diagram shows a cross-sectional structure after the formation of an organic protective material layer in the fabrication method of the waveguide device of the present invention.
[0027] Figure 5 The diagram shows a cross-sectional structure of the waveguide device fabrication method of the present invention after the formation of an organic protective layer.
[0028] Figure 6 The diagram shows a cross-sectional structure of the waveguide device fabrication method of the present invention after the formation of the isolation layer.
[0029] Figure 7 The diagram shown is a cross-sectional view of the waveguide device fabrication method of the present invention after the formation of the microstructure.
[0030] Figure 8 The diagram shows a cross-sectional structure of the waveguide device fabrication method of the present invention after removing the covering organic protective layer to expose the isolation layer on the upper surface.
[0031] Figure 9 The diagram shows a cross-sectional structure after removing the organic protective layer, which is a method for fabricating the waveguide device of the present invention.
[0032] Explanation of icon numbers
[0033] 1. Wafer
[0034] 11 Substrate
[0035] 12. Buried Oxygen Layer
[0036] 13 Device Layer
[0037] 14 First District
[0038] 15 Second District
[0039] 16 Waveguide Structure
[0040] 2 Organic protective layer
[0041] 21 Organic protective material layer
[0042] 3. Isolation layer
[0043] 4. Microstructure Detailed Implementation
[0044] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0045] Please see Figures 1 to 9 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.
[0046] This embodiment provides a method for fabricating a waveguide device, such as... Figure 1 The diagram shows a flowchart of the fabrication method for the waveguide device, including the following steps:
[0047] S1: A wafer with a device layer disposed on its upper surface is provided, the wafer including a first region and a second region;
[0048] S2: A waveguide structure is formed in the device layer on the upper surface of the first region, and an organic protective layer is formed on the upper surface of the first region that at least covers the exposed surface of the waveguide structure.
[0049] S3: Form an isolation layer covering the exposed upper surface of the wafer and the exposed surface of the organic protective layer;
[0050] S4: Form a microstructure above the second region and remove the isolation layer covering the organic protective layer to expose the upper surface;
[0051] S5: Remove the protective layer.
[0052] Please see Figures 2 to 6 The following steps are performed: Step S1, Step S2, and Step S3 are performed: A wafer 1 with a device layer 13 on its upper surface is provided, the wafer 1 including an adjacent first region 14 and a second region 15; a waveguide structure 16 is formed in the device layer 13 on the upper surface of the first region 14, and an organic protective layer 2 is formed on the upper surface of the first region 14 to at least cover the exposed surface of the waveguide structure 16; an isolation layer 3 is formed to cover the exposed upper surface of the wafer 1 and the exposed surface of the organic protective layer 2.
[0053] As an example, such as Figure 2The diagram shown is a cross-sectional view of the wafer 1. The wafer 1 also includes a substrate 11 and a buried oxide layer 12 stacked sequentially, and the device layer 13 is located on the upper surface of the buried oxide layer 12.
[0054] Specifically, while ensuring the performance of the waveguide device, the size, thickness and shape of the wafer 1 can be selected according to the actual situation, and are not limited here.
[0055] Specifically, the substrate 11 serves as a process platform for fabricating waveguide devices, and the buried oxide layer 12 is used to prevent the light field from leaking from the substrate 11, thereby improving the efficiency of the waveguide in the waveguide structure 16. While ensuring the performance of the waveguide device, the thickness of the substrate 11 can be selected according to the actual situation, and is not limited here; the thickness of the buried oxide layer 12 can be selected according to the actual situation, and is not limited here.
[0056] Specifically, the substrate 11 is made of silicon, silicon oxide, or other suitable materials; the buried oxide layer 12 is made of silicon oxide or other suitable materials. In this embodiment, a silicon layer is used as the substrate 11, and a silicon oxide layer is used as the buried oxide layer 12.
[0057] Specifically, the device layer 13 is mainly used to fabricate the waveguide structure 16 in the waveguide device, and the material of the device layer 13 includes silicon, silicon nitride, silicon oxynitride, lithium niobate, aluminum nitride, silicon carbide or other suitable materials.
[0058] Specifically, while ensuring the performance of the waveguide device, the thickness of the device layer 13 can be selected according to the actual situation, and is not limited here.
[0059] Specifically, such as Figure 3 The diagram shows a cross-sectional view of the waveguide structure 16 after its formation. The first region 14 is used to fabricate the waveguide structure 16 in the waveguide device, and the second region 15 is used to fabricate the non-waveguide structure in the waveguide device. While ensuring the performance of the waveguide device, the size and shape of the first region 14 can be selected according to the actual situation and are not limited here. The size and shape of the second region 15 can also be selected according to the actual situation and are not limited here. The first region 14 and the second region 15 can be arranged adjacent to each other or separated by a preset distance.
[0060] Specifically, the method for forming the waveguide structure 16 in the device layer 13 on the upper surface of the first region 14 includes the following steps: forming a patterned first masking layer on the upper surface of the device layer 13, and etching the device layer 13 based on the patterned first masking layer to obtain the waveguide structure 16 located on the upper surface of the buried oxide layer 12 in the first region 14.
[0061] Specifically, the first masking layer is usually a photoresist layer. The method for forming the patterned first masking layer is the commonly used photoresist layer coating, drying, exposure, and development process, which will not be elaborated here.
[0062] Specifically, the method for etching the device layer 13 based on the patterned first masking layer includes dry etching, wet etching, or other suitable methods.
[0063] Specifically, while ensuring the performance of the waveguide device, the length, shape, cross-sectional size and cross-sectional shape of the waveguide structure 16 can be selected according to the actual situation, and are not limited here.
[0064] Specifically, after forming the waveguide structure 16 and before forming the organic protective layer 2, the process also includes a step of removing the photoresist layer.
[0065] Specifically, the method for removing the photoresist layer is a commonly used photoresist stripping method, which will not be described in detail here.
[0066] As an example, forming the organic protective layer 2 includes the following steps: forming an organic protective material layer 21 of a predetermined thickness on the upper surface of the wafer 1 after forming the waveguide structure 16; forming a patterned masking layer on the upper surface of the organic protective material layer 21; and etching the organic protective material layer 21 based on the patterned masking layer to obtain the organic protective layer 2 covering the exposed surface of the waveguide structure 16.
[0067] Specifically, the organic protective layer 2 is used to protect the waveguide structure 16 after it has been formed, so as to prevent damage to the waveguide structure 16 when other related structures in the waveguide device are fabricated.
[0068] As an example, such as Figure 4 The diagram shown is a cross-sectional view of the organic protective material layer 21 after its formation. The methods for forming the organic protective material layer 21 include spin coating, chemical vapor deposition, or other suitable methods. Preferably, chemical vapor deposition is used to form the organic protective material layer 21.
[0069] Specifically, the masking layer is a commonly used mask layer, which is used to protect the organic protective material layer 21 of the non-etched part during the formation of the organic protective layer 2, so as to obtain the organic protective layer 2.
[0070] Specifically, since the organic protective material layer 21 is an organic material layer, if the organic protective material layer 21 is not a photoresist layer, a hard mask layer is usually provided between the organic protective material layer 21 and the photoresist layer. That is, the masking layer is a composite film layer composed of the photoresist layer and the hard mask layer. The method of patterning the masking layer is the commonly used photolithography process, which will not be described in detail here.
[0071] Specifically, the pattern in the patterned masking layer reveals the organic protective material layer that needs to be removed.
[0072] Specifically, if the organic protective material layer 21 is a photoresist layer, then the excess organic protective material layer 21 is removed using a common photolithography process, and there is no need to form the masking layer.
[0073] As an example, the method of etching the organic protective material layer 21 includes dry etching or other suitable methods.
[0074] As an example, such as Figure 5 The diagram shown is a cross-sectional view of the organic protective layer 2 after its formation. The organic protective layer 2 is made of at least one of photoresist, epoxy resin, PI (polyimide), and PBO (polybenzoxazole). It can be a film layer composed of a single organic material or a composite film layer composed of multiple organic film layers. Preferably, a single PI layer is used as the organic protective layer 2.
[0075] Specifically, the thickness of the organic protective layer 2 can be selected according to the actual situation, provided that the subsequent process does not damage the waveguide structure 16. There are no restrictions here.
[0076] As an example, the organic protective layer 2 covers the exposed surface of the waveguide structure 16 and also covers the exposed upper surface of the first region 14.
[0077] Specifically, while ensuring the performance of the waveguide device, the organic protective layer 2 may only cover the exposed surface of the waveguide structure 16 in the first region 14.
[0078] Specifically, before forming the organic protective layer 2 and the isolation layer 3 based on the masking layer, the process includes a step of removing the masking layer. The removal of the masking layer is done using a commonly used method for removing photoresist layers or photoresist layers and hard mask layers, which will not be elaborated here.
[0079] As an example, such as Figure 6 The diagram shown is a cross-sectional view of the isolation layer 3 after its formation. The material of the isolation layer 3 includes silicon oxide or other suitable materials.
[0080] Specifically, the method for forming the isolation layer 3 includes chemical vapor deposition, physical vapor deposition, or other suitable methods.
[0081] Specifically, while ensuring the performance of the waveguide device, the thickness and shape of the isolation layer 3 can be selected according to the actual situation, and are not limited here.
[0082] Please see again Figures 7 to 9 Perform steps S4 and S5: form a microstructure 4 above the second region 15 and remove the isolation layer 3 covering the exposed upper surface of the organic protective layer 2; remove the organic protective layer 2 using an ashing process.
[0083] Specifically, such as Figure 7 The diagram shown is a cross-sectional view of the microstructure 4 after its formation. The microstructure 4 is a non-waveguide component in the waveguide device. The size and structure of the microstructure 4 can be selected according to the actual situation and are not limited here.
[0084] As an example, the microstructure 4 is embedded in the isolation layer 3 above the second region 15.
[0085] Specifically, while ensuring the performance of the waveguide device, the microstructure 4 can also be located on the upper surface of the isolation layer 3. In this embodiment, the microstructure 4 is embedded in the isolation layer 3 above the second region 15.
[0086] Specifically, removing the isolation layer 3 covering the exposed upper surface of the organic protective layer 2 includes the following steps: forming a second masking layer on the upper surface of the isolation layer 3 covering the upper surface of the isolation layer 3 and the exposed surface of the microstructure 4, and patterning the second masking layer; etching the isolation layer 3 based on the patterned second masking layer.
[0087] Specifically, the process of forming and patterning the second masking layer is a commonly used photolithography process, which will not be elaborated here.
[0088] Specifically, the pattern in the patterned second masking layer reveals the upper surface of the isolation layer 3 covering a portion of the organic protective layer 2.
[0089] As an example, such as Figure 8 The diagram shown is a cross-sectional view of the structure after removing the isolation layer 3 covering the organic protective layer 2 and exposing the upper surface. The method for removing the isolation layer 3 covering the organic protective layer 2 and exposing the upper surface includes dry etching, wet etching, or other suitable methods.
[0090] Specifically, after removing the isolation layer 3 covering the exposed upper surface of the organic protective layer 2, but before removing the organic protective layer 2, the process also includes the step of removing the second masking layer.
[0091] Specifically, the method for removing the second masking layer is the commonly used photoresist layer or hard mask layer removal process, which will not be elaborated here.
[0092] Specifically, while ensuring the performance of the waveguide device, the second masking layer can also be removed simultaneously with the organic protective layer 2.
[0093] As an example, such as Figure 9 The diagram shown is a cross-sectional view of the structure after removing the organic protective layer 2. The method for removing the organic protective layer 2 includes an ashing process or other suitable methods. Preferably, an ashing process is used to remove the organic protective layer 2.
[0094] Specifically, since the organic protective layer 2 is made of organic material, an ashing process is used to allow the organic protective layer to react completely with oxygen in a high-temperature and oxygen-rich environment to generate gas, so that the organic protective layer 2 can be easily removed without residue, thus ensuring the quality of the waveguide structure 16.
[0095] Specifically, the waveguide structure 16 is first formed based on the device layer 13, and after the waveguide structure 16 is formed, an organic protective layer 2 is formed covering the exposed surface of the waveguide structure 16, wherein the organic protective layer 2 is an organic material. Then, the microstructure 4 is fabricated, and after the fabrication of the microstructure 4 is completed, the isolation layer 3 covering the upper surface of the organic protective layer 2 is removed. Finally, the organic protective layer 2 is removed by an ashing process. This avoids damage to the waveguide structure when removing the isolation layer 3 above the waveguide structure 16, and does not cause over-etching of the waveguide structure 16 or undercutting at the bottom of the waveguide structure 16, thus ensuring the morphology and quality of the waveguide structure 16.
[0096] Specifically, since the organic protective layer 2 is an organic material, it has a large selective etching ratio with the inorganic film layer used in the fabrication of the microstructure 4, which avoids damage to the waveguide structure 16 when removing the isolation layer 3 above the waveguide structure 16, resulting in better process controllability. Furthermore, the method for removing the organic protective layer 2 is simple, reducing the difficulty of fabricating the waveguide device.
[0097] In summary, the waveguide device fabrication method of the present invention improves the waveguide device fabrication process by first forming a waveguide structure based on a device layer, then protecting the waveguide structure with an organic material protective layer, followed by the fabrication of the microstructure and the removal of the isolation layer on top of the waveguide structure. Because the organic material protective layer and the isolation layer have a high etching selectivity, damage to the waveguide structure is avoided during the removal of the isolation layer. Furthermore, the ashing process used to remove the organic protective layer leaves no residue and causes no damage to the waveguide structure, ensuring the quality of the waveguide structure, reducing the difficulty of fabricating the waveguide device, improving process controllability, and simplifying the method for removing the protective layer. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.
[0098] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.
Claims
1. A method for fabricating a waveguide device, characterized in that, Includes the following steps: A wafer with a device layer disposed on its upper surface is provided, the wafer comprising a first region and a second region; A waveguide structure is formed in the device layer on the upper surface of the first region, and an organic protective layer is formed on the upper surface of the first region that at least covers the exposed surface of the waveguide structure. An isolation layer is formed covering the exposed upper surface of the wafer and the exposed surface of the organic protective layer; A microstructure is formed above the second region, and the isolation layer covering the organic protective layer is removed to expose the upper surface; Remove the organic protective layer.
2. The method for fabricating the waveguide device according to claim 1, characterized in that: The wafer also includes a substrate and a buried oxide layer stacked sequentially, with the device layer located on the upper surface of the buried oxide layer.
3. The method for fabricating the waveguide device according to claim 1, characterized in that, Forming the organic protective layer includes the following steps: An organic protective material layer of a predetermined thickness is formed on the upper surface of the wafer after the waveguide structure is formed; A patterned masking layer is formed on the upper surface of the organic protective material layer, and the organic protective material layer is etched based on the patterned masking layer to obtain an organic protective layer covering the exposed surface of the waveguide structure.
4. The method for fabricating the waveguide device according to claim 3, characterized in that: Methods for forming the organic protective material layer include spin coating and chemical vapor deposition; Methods for etching the organic protective material layer include dry etching.
5. The method for fabricating the waveguide device according to claim 1, characterized in that: The organic protective layer is made of at least one of the following materials: photoresist, epoxy resin, PI, and PBO.
6. The method for fabricating the waveguide device according to claim 1, characterized in that: The organic protective layer covers the exposed surface of the waveguide structure as well as the exposed upper surface of the first region.
7. The method for fabricating the waveguide device according to claim 1, characterized in that: The material of the isolation layer includes silicon dioxide.
8. The method for fabricating the waveguide device according to claim 1, characterized in that: The microstructure is embedded in the isolation layer.
9. The method for fabricating the waveguide device according to claim 1, characterized in that: Methods for removing the isolation layer covering the organic protective layer and exposing the upper surface include dry etching and wet etching.
10. The method for fabricating the waveguide device according to claim 1, characterized in that: The method for removing the organic protective layer includes an ashing process.