Preparation process of multi-height waveguide

Abstract

Disclosed are a preparation process of a multi-height waveguide. The preparation process comprises the following steps: providing a substrate, forming a first coating layer on one surface of the substrate, and forming a first waveguide layer on the surface of the first coating layer away from the substrate; performing a first photolithography and etching on the first waveguide layer to complete full-height region patterning of the multi-height waveguide; performing a secondary photolithography and etching on the first waveguide layer to shallow-layer region patterning of the multi-height waveguide; performing a third photolithography and etching on the first waveguide layer to complete deep-layer region patterning of the multi-height waveguide; wherein the etching is a gradually etching using a hard mask self-alignment mode. In the present invention, a hard mask self-alignment mode is used for gradual etching, the pattern of each height is self-aligned, the corresponding layout areas and the process are clear, designers can conveniently use automatic scripts for automatic drawing, and the performance and the design intuitiveness of the device are also improved.

Description

A preparation process for multi-height waveguide

[0001] Cross-references

[0002] This application claims priority to Chinese application No. 202311030422.9, filed on August 16, 2023. The contents of the above application are incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of chip preparation, and in particular to a preparation process of a multi-height waveguide. Background Art

[0004] With the rapid development of the information industry and the advent of the Internet of Things, cloud computing, and big data, people are increasingly demanding higher capacity and processing speed for information data. Although the development of Moore's Law has gradually reduced the size of traditional microelectronic devices and continuously improved their performance and power consumption, the huge demand for data applications has led to increasingly prominent shortcomings in speed and power consumption. Photonic integrated circuits (PICs) offer significant advantages in size, power consumption, cost, and reliability, making them the mainstream of future development.

[0005] Waveguides and various optical devices, as carriers for signal loading, transmission, and conversion, are key technologies in optical integrated chips. Different performance requirements require waveguides and optical devices of varying shapes, which in turn requires varying thicknesses of optical waveguide materials.

[0006] Currently, there are two approaches to processing optical waveguide materials of varying heights. One involves step-by-step etching, where each step etches a specific amount, cumulatively resulting in a full etch. A major issue with this approach is that shell deviations between steps can create unstable step heights, particularly between partial ET steps, impacting performance stability. The other involves completely independent etching. This approach is cumbersome to process, requiring careful consideration of the overlap between etching steps. This increases layout complexity and hinders layout design.

[0007] Summary of the Invention

[0008] In order to solve at least one technical problem of the prior art, the present invention provides a process for preparing a multi-height waveguide.

[0009] To achieve the above-mentioned object, the present invention adopts a technical solution: a process for preparing a multi-height waveguide, wherein the multi-height waveguide includes a full-height region, a shallow-engraved region, and a deep-engraved region, wherein the height of the full-height region from the substrate is greater than the height of the shallow-engraved region from the substrate, and the height of the shallow-engraved region from the substrate is greater than the height of the deep-engraved region from the substrate, comprising the following steps:

[0010] Step 1: providing a substrate, forming a first cladding layer on a surface of the substrate, and forming a first waveguide layer on a surface of the first cladding layer away from the substrate;

[0011] Step 2: performing a first photolithography and etching on the first waveguide layer to complete full-height area patterning of the multi-height waveguide;

[0012] Step 3: performing a second photolithography and etching on the first waveguide layer to complete the patterning of the shallow etching area of ​​the multi-height waveguide;

[0013] Step 4: performing a third photolithography and etching on the first waveguide layer to complete deep area patterning of the multi-height waveguide;

[0014] The etching is performed step by step in a hard mask self-alignment manner.

[0015] Furthermore, the first waveguide layer is subjected to a first photolithography and etching process to complete full-height region patterning of the multi-height waveguide, including:

[0016] Depositing a first hard mask layer on a surface of the first waveguide layer away from the substrate;

[0017] The first waveguide layer is patterned by using a photolithography and etching process to form a full-height region of a multi-height waveguide, and the first hard mask layer of the full-height region is retained.

[0018] Further, forming the first hard mask layer by thin film deposition;

[0019] The thin film can be made of aluminum nitride, aluminum oxynitride, aluminum oxide, polysilicon, silicon nitride, silicon oxynitride, silicon dioxide, SiCN or SiOCH.

[0020] Furthermore, the first waveguide layer is subjected to a second photolithography and etching process to complete the patterning of the shallow etching area of ​​the multi-height waveguide, including:

[0021] removing photoresist residues on the surface of the first waveguide layer, and forming a first organic dielectric layer covering the full-height area on the surface of the first waveguide layer away from the substrate;

[0022] Depositing a second hard mask layer on a surface of the first organic dielectric layer away from the substrate;

[0023] The first waveguide layer is patterned by using a photolithography and etching process to form a shallow etching area of ​​a multi-height waveguide, and a second hard mask layer is retained above the shallow etching area.

[0024] Further, forming the second hard mask layer by thin film deposition;

[0025] The thin film can be made of aluminum nitride, aluminum oxynitride, aluminum oxide, polysilicon, silicon nitride, silicon oxynitride, silicon dioxide, SiCN or SiOCH.

[0026] Furthermore, in the second etching process, the second hard mask layer is etched first, then the first organic dielectric layer is etched, and finally the first waveguide layer is etched.

[0027] Furthermore, the first organic dielectric layer is formed by coating an organic dielectric layer with a preset thickness on the full-height area and the surface of the first waveguide layer;

[0028] The first organic dielectric layer can be made of amorphous carbon, BARC, CHM701B, HM8006, HM8014, ODL-102 or other commercially available adhesives.

[0029] Furthermore, the first waveguide layer is subjected to a third photolithography and etching process to complete deep region patterning of the multi-height waveguide, including:

[0030] forming a second organic dielectric layer covering the full-height area and the shallow-etched area on a surface of the first waveguide layer away from the substrate;

[0031] Depositing on the surface of the second organic dielectric layer to form a third hard mask layer;

[0032] The first waveguide layer is patterned using a photolithography and etching process to form a deep region of multi-height waveguides;

[0033] Remove the remaining photoresist.

[0034] Further, forming the third hard mask layer by thin film deposition;

[0035] The thin film can be made of aluminum nitride, aluminum oxynitride, aluminum oxide, polysilicon, silicon nitride, silicon oxynitride, silicon dioxide, SiCN or SiOCH.

[0036] Furthermore, in the third etching process, the third hard mask layer is etched first, then the second organic dielectric layer is etched, and finally the first waveguide layer is etched.

[0037] Furthermore, the etching may be performed by dry etching or wet etching.

[0038] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0039] The present invention uses a hard mask (HM) self-aligned etching method to form a multi-height waveguide device without steps. Since the pattern of each height is self-aligned, unstable step heights caused by shell deviation will not be caused. The overlapping parts of different heights are determined by the pattern of the thickest layer. The corresponding areas of the layout and process are clear, which facilitates designers to use automated scripts for automatic drawing, while improving device performance and design intuitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG1 is a schematic structural diagram of a multi-height waveguide in Example 1;

[0041] FIG2 is a schematic diagram of the morphology of a multi-height waveguide in step 1 of a preparation process of a multi-height waveguide in Example 1;

[0042] FIG3 is a first schematic diagram of the morphology of a multi-height waveguide in step 2 of a preparation process of a multi-height waveguide in Example 1;

[0043] FIG4 is a second schematic diagram of the morphology of a multi-height waveguide in step 2 of a preparation process of a multi-height waveguide in Example 1;

[0044] FIG5 is a first schematic diagram of the morphology of a multi-height waveguide in step three of a process for preparing a multi-height waveguide in Example 1;

[0045] FIG6 is a second schematic diagram of the morphology of a multi-height waveguide in step three of the preparation process of a multi-height waveguide in Example 1;

[0046] FIG7 is a first schematic diagram of the morphology of a multi-height waveguide in step four of a process for preparing a multi-height waveguide in Example 1;

[0047] FIG8 is a second schematic diagram of the morphology of a multi-height waveguide in step four of the preparation process of a multi-height waveguide in Example 1;

[0048] FIG9 is a schematic diagram of a multi-height waveguide structure manufactured by a multi-height waveguide manufacturing process in Example 1. DETAILED DESCRIPTION

[0049] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. These drawings are all simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner. Therefore, they only show the structures related to the present invention. It should be noted that, unless there is a conflict, the embodiments in this application and the features in the embodiments can be combined with each other.

[0050] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0051] Example 1

[0052] 1 , a multi-height waveguide includes a substrate 1, a cladding layer 2 formed on a surface of the substrate 1, and a first waveguide 3 formed on a surface of the cladding layer 2 away from the substrate 1. The first waveguide 3 includes a full-height region 30, a shallow-engraved region 31, and a deep-engraved region 32. A height of the full-height region 30 from the substrate 1 is greater than a height of the shallow-engraved region 31 from the substrate 1, and a height of the shallow-engraved region 31 from the substrate 1 is greater than a height of the deep-engraved region 32 from the substrate 1.

[0053] The present invention provides a process for preparing a multi-height waveguide to form the multi-height waveguide. The process for preparing the multi-height waveguide comprises the following steps:

[0054] Step 1: providing a substrate 1, forming a first cladding layer 2 on one surface of the substrate 1, and forming a first waveguide layer a on a surface of the first cladding layer 2 away from the substrate 1;

[0055] Step 2: performing a first photolithography and etching on the first waveguide layer a to complete full-height area patterning of the multi-height waveguide;

[0056] Step 3: performing a second photolithography and etching on the first waveguide layer a to complete the patterning of the shallow etching area of ​​the multi-height waveguide;

[0057] Step 4: performing a third photolithography and etching on the first waveguide layer a to complete deep area patterning of the multi-height waveguide;

[0058] The etching is performed step by step in a hard mask self-alignment manner.

[0059] Because hard mask self-aligned etching is used in a stepwise manner, overlay deviation and unstable step heights caused by overlay deviation are eliminated. The overlap of different heights is determined by the pattern of the thickest layer. The corresponding areas of the layout and process are clearly defined, making it easier for designers to use automated scripts for automatic drawing, while improving device performance and design intuitiveness.

[0060] Furthermore, the substrate 1 may be an optical / electromagnetic waveguide chip substrate such as silicon, lithium niobate or III-V compounds.

[0061] Further, referring to FIG3 and FIG4 , the first waveguide layer a is subjected to a first photolithography and etching process to complete full-height region patterning of the multi-height waveguide, including:

[0062] Depositing a first hard mask layer b on a surface of the first waveguide layer a away from the substrate 1;

[0063] The first waveguide layer a is patterned by using a photolithography and etching process to form a full-height region 30 of a multi-height waveguide, and the first hard mask layer b above the full-height region 30 is retained.

[0064] The depth h1 of the first etching is the depth required for the shallow etching area 31 , that is, the depth h1 of the first etching is the height difference between the top of the full-height area 30 and the top of the shallow etching area 31 .

[0065] Furthermore, the first hard mask layer b is formed by thin film deposition, and the first hard mask layer b has a high etching selectivity ratio with the first waveguide layer.

[0066] Preferably, the thin film may be made of aluminum nitride, aluminum oxynitride, aluminum oxide, polysilicon, silicon nitride, silicon oxynitride, silicon dioxide, SiCN or SiOCH.

[0067] Furthermore, the deposition may be performed using LPCVD, PECVD, ALD or PVD processes.

[0068] 5 and 6 , the first waveguide layer a is subjected to a second photolithography and etching process to complete the patterning of the shallow etching region 31 of the multi-height waveguide, including:

[0069] Removing the photoresist c remaining on the surface of the first waveguide layer a, and forming a first organic dielectric layer d covering the full-height area 30 on the first waveguide layer a away from the substrate 1;

[0070] Depositing a second hard mask layer e on a surface of the first organic dielectric layer d away from the substrate a;

[0071] The first waveguide layer a is patterned by using a photolithography and etching process to form a shallow-etched region 31 of a multi-height waveguide, and the second hard mask layer e is retained above the shallow-etched region 31 .

[0072] Furthermore, the second hard mask layer e is formed by thin film deposition. Preferably, the second hard mask layer e is formed by depositing aluminum nitride, aluminum oxynitride, aluminum oxide, polysilicon, silicon nitride, silicon oxynitride, silicon dioxide, SiCN or SiOCH.

[0073] Furthermore, in the second etching process, the second hard mask layer e is etched first, then the first organic dielectric layer d is etched, and finally the first waveguide layer a is etched.

[0074] The full-height region 30 is located in the photolithographically opened area. After etching of the first organic dielectric layer d is complete, the first hard mask layer b above the full-height region 30 is exposed. As the first waveguide layer a is further etched, the first hard mask layer b acts as a hard mask to protect the full-height region 30 from etching. The shallowly etched region 31 is protected by the photoresist and second hard mask layer e from etching. Etching continues downwards through the remainder of the first waveguide layer a until the etch depth h2 reaches the desired depth for the deep region 32.

[0075] Furthermore, the first organic dielectric layer d is formed by coating an organic dielectric with a predetermined thickness on the surface of the full height area 30 and the first waveguide layer a;

[0076] The organic dielectric may be made of amorphous carbon, BARC, CHM701B, HM8006, HM8014, ODL-102 or other commercial adhesives.

[0077] 7 and 8 , the first waveguide layer a is subjected to a third photolithography and etching process to complete the patterning of the deep region 32 of the multi-height waveguide, including:

[0078] forming a second organic dielectric layer f covering the full-height area 30 and the shallow-etched area 31 on the surface of the first waveguide layer a away from the substrate 1;

[0079] Depositing on the surface of the second organic dielectric layer f to form a third hard mask layer g;

[0080] The first waveguide layer a is patterned using a photolithography and etching process to form a deep region of multi-height waveguides;

[0081] The remaining first hard mask b is removed.

[0082] Furthermore, the third hard mask layer g is formed by thin film deposition. Preferably, the third hard mask layer g is formed by depositing aluminum nitride, aluminum oxynitride, aluminum oxide, polysilicon, silicon nitride, silicon oxynitride, silicon dioxide, SiCN or SiOCH.

[0083] Furthermore, during the etching process, the third hard mask layer g is etched first, then the second organic dielectric layer f is etched, and finally the first waveguide layer a is etched.

[0084] The full-height region 30 and the shallowly etched region 31 are located in the open area of ​​the photoresist. After etching the second organic dielectric layer f, the first hard mask layer b above the full-height region 30 and the second hard mask layer e above the shallowly etched region 31 are exposed. As the waveguide layer etching continues, the first waveguide layer a is further etched. The full-height region 30 is protected by the first hard mask layer b as a hard mask. The shallowly etched region 31 is protected by the second hard mask layer e. The deep region 32 is protected by the photoresist and the third hard mask layer g. Etching continues downwards on the remaining areas of the first waveguide layer until the first waveguide layer is completely etched. After the third etching, the second hard mask layer e and the third hard mask layer g are completely consumed. The remaining first organic dielectric layer d and the second organic dielectric layer f can be removed by ashing or stripping.

[0085] Furthermore, the remaining first hard mask b can be removed by etching with a high selectivity ratio, or can be temporarily retained to form a stop layer in a subsequent CMP process of the cladding layer before being removed.

[0086] Furthermore, the etching may be performed by dry etching or wet etching.

[0087] It should be noted that the preparation process of a multi-height waveguide of the present invention is not limited to the preparation of the three-layer height waveguide of the above embodiment, and can also be expanded to more thickness levels according to application requirements.

[0088] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0089] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to the above embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A process for preparing a multi-height waveguide, wherein the multi-height waveguide comprises a full-height region, a shallow-engraved region and a deep-engraved region, wherein the height of the full-height region from the substrate is greater than the height of the shallow-engraved region from the substrate, and the height of the shallow-engraved region from the substrate is greater than the height of the deep-engraved region from the substrate, characterized in that: The following steps are involved: Step 1: providing a substrate, forming a first cladding layer on a surface of the substrate, and forming a first waveguide layer on a surface of the first cladding layer away from the substrate; Step 2: performing the first photolithography and etching on the first waveguide layer to complete full-height area patterning of the multi-height waveguide, including: Depositing a first hard mask layer on a surface of the first waveguide layer away from the substrate; The first waveguide layer is patterned by using a photolithography and etching process to form a full-height region of a multi-height waveguide, and the first hard mask layer above the full-height region is retained; The depth of the first etching is the depth required for the shallow etching area, that is, the depth of the first etching is the height difference from the top of the full-height area to the top of the shallow etching area; Step 3: performing a second photolithography and etching on the first waveguide layer to complete the patterning of the shallow etching area of ​​the multi-height waveguide, including: Removing photoresist residues from the surface of the first waveguide layer, and forming a first organic dielectric layer covering the full-height area on the surface of the first waveguide layer away from the substrate; Depositing a second hard mask layer on a surface of the first organic dielectric layer away from the substrate; The first waveguide layer is patterned by using a photolithography and etching process to form a shallow-etched region of a multi-height waveguide, and a second hard mask layer is retained above the shallow-etched region; In the second etching process, the second hard mask layer is etched first, then the first organic dielectric layer is etched, and finally the first waveguide layer is etched. The full-height area is in the photolithography open area. When the first organic dielectric layer is etched, the first hard mask layer above the full-height area is exposed. In the process of continuing to etch the first waveguide layer, the full-height area is protected by the first hard mask layer as a hard mask and is not etched. The shallow etching area is protected by the photoresist and the second hard mask layer and is not etched, while the remaining area of ​​the first waveguide layer continues to be etched downwards, and the etching depth accumulates to the required depth of the deep area and stops; Step 4: Performing a third photolithography and etching on the first waveguide layer to complete deep area patterning of the multi-height waveguide, including: Forming a second organic dielectric layer covering the full-height area and the shallow-etched area on a surface of the first waveguide layer away from the substrate; Depositing on the surface of the second organic dielectric layer to form a third hard mask layer; The first waveguide layer is patterned by using a photolithography and etching process to form a deep region of multi-height waveguides; In the third etching process, the third hard mask layer is etched first, then the second organic dielectric layer is etched, and finally the first waveguide layer is etched. The full-height area and the shallow-etched area are in the photoresist open area. When the etching of the second organic dielectric layer is completed, the first hard mask layer above the full-height area and the second hard mask layer above the shallow-etched area are exposed. In the process of continuing to etch the first waveguide layer by the waveguide layer etching, the full-height area is protected by the first hard mask layer as a hard mask and is not etched, the shallow-etched area is protected by the second hard mask layer and is not etched, and the deep-etched area is protected by the photoresist and the third hard mask layer and is not etched. The remaining area of ​​the first waveguide layer continues to be etched downward until the first waveguide layer is completely etched. The etching is performed step by step in a hard mask self-alignment manner.

2. The preparation process according to claim 1, characterized in that: forming the first hard mask layer by thin film deposition; The film is selected from aluminum nitride, aluminum oxynitride, aluminum oxide, polysilicon, silicon nitride, silicon oxynitride, silicon dioxide, SiCN or SiOCH.

3. The preparation process according to claim 1, characterized in that: forming the second hard mask layer by thin film deposition; The film is selected from aluminum nitride, aluminum oxynitride, aluminum oxide, polysilicon, silicon nitride, silicon oxynitride, silicon dioxide, SiCN or SiOCH.

4. The preparation process according to claim 1, characterized in that: Forming the first organic dielectric layer by coating an organic dielectric layer with a preset thickness on the full height area and the surface of the first waveguide layer; The first organic dielectric layer is made of amorphous carbon, BARC, CHM701B, HM8006, HM8014 or ODL-102.

5. The preparation process according to claim 1, characterized in that: forming the third hard mask layer by thin film deposition; The film is selected from aluminum nitride, aluminum oxynitride, aluminum oxide, polysilicon, silicon nitride, silicon oxynitride, silicon dioxide, SiCN or SiOCH.

6. The preparation process according to claim 1, characterized in that: The etching is performed by dry etching or wet etching.

7. The preparation process according to claim 2, characterized in that: The etching is performed by dry etching or wet etching.

8. The preparation process according to claim 3, characterized in that: The etching is performed by dry etching or wet etching.

9. The preparation process according to claim 4, characterized in that: The etching is performed by dry etching or wet etching.

10. The preparation process according to claim 5, characterized in that: The etching is performed by dry etching or wet etching.

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