A preparation method applied to a 2.5-dimensional heterogeneous integrated optical waveguide
Patent Information
- Application Number
- CN202311859495.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-30
- Publication Date
- 2026-10-13
- Estimated Expiration
- 2043-12-30
AI Technical Summary
根据调研，暂时还未有报道对2.5维硅基异质集成进行详细的定义以及工艺设计
本发明公开了一种应用于2.5维异质集成光波导的制备方法，不同于传统垂直堆叠的3维集成，2.5维是指光波导器件处于同一平面，其自身高度可以不一致，在平面上进行异质结构的功能拓展。一般的3维异质集成工艺需要经历沉积、光刻、磨抛、刻蚀、晶片对准、粘合等多道严格的工艺。此外，3维封装需要进行直接键合技术的高难度的制造工艺。苛刻的抛光、粘合和直接键合等工艺，对耦合器结构尺寸的精度提出巨大的挑战，也大大影响成品率。然而，“2.5维”不需要经历3维集成苛刻的抛光、晶片对准和键合工艺，同时，结合本发明所提出的2.5维异质集成的制备方法，采用原子层沉积(Atomic Layer Deposition，ALD)沉积氧化铝薄膜，其厚度为5~50 nm，由于这种材料在很宽的波段上都是无吸收的，并且很硬难以刻蚀掉，可以作为其他异质材料结构刻蚀时的一个保护层，并且很薄的氧化铝薄膜层对异质集成器件的性能没有影响，这里巧妙地利用氧化铝薄膜作为刻蚀保护层，可以进一步避免复杂的对准和粘合工艺，大大简化了工艺制备的步骤。
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Figure CN117970567B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to an on-chip fabrication method in the field of heterogeneous integration, specifically to a fabrication method for 2.5-dimensional heterogeneous integrated optical waveguides. Background Technology
[0002] Heterogeneous integration refers to integrating different types of materials, devices, or structures into the same system or chip to achieve new functions or performance. This integration can include different types of semiconductor materials, devices with different functions, and even components from different manufacturing processes. Traditional monolithic integration, which uses only a single material to design planar waveguide devices, has limited performance. Therefore, this multi-material heterogeneous integration scheme can greatly increase the functional variety and capability limits of optical chip systems, achieving complementary advantages of various materials. Research has demonstrated that silicon-based heterogeneous integrated optical chips exhibit significant advantages in core indicators such as performance, loss, bandwidth, and power consumption, and have wide applications in integrated circuits, optoelectronic devices, sensors, and micro / nano systems. Based on the structural characteristics of silicon-based heterogeneous integration, it can be divided into 3D integration and 2.5D integration. According to research, there are currently no reports providing a detailed definition and process design for 2.5D silicon-based heterogeneous integration.
[0003] Typical 3D integration refers to integrating multiple functional chips vertically stacked to form a three-dimensional structure. Direct bonding technology is used to achieve the shortest interconnect length and smallest package size. This typically involves multiple rigorous processes such as deposition, photolithography, polishing, etching, wafer alignment, and bonding. Unlike 3D integration, 2.5D silicon-based heterogeneous integration involves integrating other functional materials or devices onto the surface of a silicon substrate. This enhances or expands functionality on the same plane. Chips are fabricated using specialized semiconductor processes, utilizing extremely high interconnect density to achieve functional enhancement or expansion. This typically involves processes such as deposition, photolithography, etching, alignment, and bonding. Summary of the Invention
[0004] This invention addresses the shortcomings of existing technologies by providing a method for fabricating 2.5D heterogeneous integrated optical waveguides. It defines the novel "2.5D" heterogeneous integration in detail and offers a novel fabrication method for 2.5D heterogeneous integration technology. This invention cleverly utilizes an alumina thin film as an etching protective layer, avoiding cumbersome polishing, alignment, bonding, and other processes. Compared to 3D heterogeneous integration, the 2.5D heterogeneous integration proposed in this invention is simpler in design, has higher precision, and is easier to fabricate. This invention provides a novel 2.5D fabrication method and fundamental technical support for heterogeneous integration technology. This invention is implemented using the following technical solutions: This invention discloses a method for fabricating 2.5-dimensional heterogeneous integrated optical waveguides, the specific steps of which are as follows: 1) Prepare and clean the wafer sample. Spin-coat photoresist onto the sample and use electron beam lithography (EBL) and inductively coupled plasma (ICP) to pattern and etch the structure of the corresponding material on the wafer sample to form the first material waveguide. The material of the first material waveguide can be common materials such as silicon (Si), silicon nitride (SiN), lithium niobate (LN), and III-V group materials. 2) On the surface formed in step 1), an aluminum oxide thin film with a thickness of 5~50 nm is deposited by atomic layer deposition (ALD) to form an aluminum oxide thin film layer. Since this material is non-absorbent over a wide wavelength range and is very hard and difficult to etch, it can be used as a protective layer during the etching of the second material waveguide. Furthermore, the very thin aluminum oxide thin film layer has no impact on the performance of heterogeneous integrated devices. 3) Deposit other heterogeneous material layers on the surface of the alumina thin film formed in step 2) using chemical vapor deposition, physical vapor deposition, or sputtering, and spin-coat photoresist on it a second time. Pattern the other heterogeneous material layers and etch them by electron beam exposure and inductively coupled plasma etching to form a second material waveguide. When etching reaches the alumina thin film, it will stop etching until the unwanted other heterogeneous materials are completely etched away. The materials of the second material waveguide are silicon nitride (SiN), titanium dioxide (TiO2), tinplate glass, germanium (Ge), etc.
[0005] 4) After the resist is stripped off, the structure of the heterogeneous integrated optical waveguide device is formed. Finally, a cladding layer is deposited on the surface of the entire structure as waveguide protection. As a further improvement, the 2.5D heterogeneous integration described in this invention refers to the first material waveguide formed in step 1) and the second material waveguide formed in step 3) being on the same horizontal plane, that is, integrating other functional materials or devices onto the same substrate plane to achieve functional enhancement or expansion, and the heights of different heterogeneous materials can be different.
[0006] The present invention discloses the following technical effects: This invention discloses a method for fabricating 2.5D heterogeneous integrated optical waveguides. Unlike traditional vertically stacked 3D integration, 2.5D refers to optical waveguide devices being located on the same plane, with varying heights, allowing for functional expansion of heterogeneous structures on a plane. Typical 3D heterogeneous integration processes require multiple rigorous steps, including deposition, photolithography, polishing, etching, wafer alignment, and bonding. Furthermore, 3D packaging requires highly complex manufacturing processes using direct bonding technology. The demanding polishing, bonding, and direct bonding processes pose significant challenges to the dimensional accuracy of the coupler structure and greatly affect the yield rate. However, "2.5D" does not require the stringent polishing, wafer alignment, and bonding processes of 3D integration. Furthermore, combined with the fabrication method of 2.5D heterogeneous integration proposed in this invention, atomic layer deposition (ALD) is used to deposit an alumina film with a thickness of 5-50 nm. Since this material is non-absorbent over a wide wavelength range and is very hard and difficult to etch, it can serve as a protective layer during the etching of other heterogeneous material structures. Moreover, the very thin alumina film layer has no impact on the performance of heterogeneous integrated devices. Here, the alumina film is cleverly used as an etching protective layer, which can further avoid complex alignment and bonding processes, greatly simplifying the fabrication steps. Attached Figure Description
[0007] Figure 1 This is a flowchart of the fabrication method for 2.5D heterogeneous integrated optical waveguides; in, Figure 1 (a) is a structural diagram of silicon on a standard insulator; Figure 1 (b) is a structural diagram of the completed silicon material structure; Figure 1 (c) is a structural diagram after the deposition of an alumina film; Figure 1 (d) is a structural diagram after the deposition of other heterogeneous material layers; Figure 1 (e) is a structural diagram of other heterogeneous material structures after completion; Figure 1 (f) is the final structure diagram after the deposition of the silica cladding. Detailed Implementation
[0008] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0009] This invention discloses a method for fabricating 2.5-dimensional heterogeneous integrated optical waveguides. Taking 2.5-dimensional silicon-based heterogeneous integration as an example, its general structure from bottom to top includes: a substrate, silicon waveguides and other heterogeneous waveguides located on the same plane, and a silicon dioxide cladding.
[0010] like Figure 1 As shown in (a), firstly, a standard silicon-on-insulator (SOI) wafer sample is prepared.
[0011] Secondly, photoresist is spin-coated onto the sample and pre-baked on a hot plate. This allows the solvent within the photoresist film to slowly and fully escape at a specific temperature, drying the film. Next, the silicon waveguide pattern is exposed using electron beam lithography (EBL). The pattern is then developed using a suitable photoresist developer, and the pattern is inspected under a microscope to ensure its accuracy and cleanliness. Once the pattern meets the requirements, post-baking is performed to facilitate the diffusion of photoreaction products. Finally, the silicon waveguide is etched using inductively coupled plasma (ICP). The photoresist used for pattern protection is then stripped off, resulting in the final waveguide as shown. Figure 1 As shown in (b); silicon materials can also be common materials such as silicon nitride (SiN), lithium niobate (LN), and III-V group materials; Secondly, such as Figure 1 As shown in (c), an alumina film is deposited using atomic layer deposition (ALD), with the thickness of the alumina film selected from 5 to 50 nm according to requirements. Since this material is non-absorbent over a wide wavelength range and is very hard and difficult to etch away, it can be used as a protective layer during the etching of other heterogeneous material structures, and the very thin alumina film layer has no impact on the performance of heterogeneous integrated devices; Secondly, such as Figure 1 As shown in (d), other heterogeneous material layers are deposited using chemical vapor deposition, physical vapor deposition, or sputtering. These layers can be silicon nitride (SiN), titanium dioxide (TiO2), tinplate glass, germanium (Ge), etc. Next, a second photoresist is spin-coated onto the surface and pre-baked. The waveguide pattern of the other heterogeneous material is then exposed using electron beam exposure. The pattern is then developed using the corresponding photoresist developer, and after microscopic inspection confirms that the pattern meets the requirements, it is post-baked. Next, inductively coupled plasma etching is used to etch the other heterogeneous material waveguide. When etching reaches the alumina film, the etching stops, continuing until all unwanted heterogeneous materials are completely etched away. After the photoresist is stripped, the structure of the silicon-based heterogeneous integrated device is formed, such as... Figure 1 As shown in (e); Ultimately, as Figure 1 As shown in (f), a silicon dioxide cladding layer is finally deposited on the surface of the entire structure as a heterogeneous waveguide protection.
[0012] The novel "2.5D" heterogeneous integration of this invention refers to integrating other functional materials or devices onto the same substrate to enhance or expand functionality on the same plane, and the heights of the different heterogeneous materials can be different. This novel 2.5D structure is simpler in both design and fabrication steps.
[0013] In summary, the fabrication method based on novel 2.5D heterogeneous integration proposed in this invention is simple in steps and easy to manufacture. The ingenious use of an alumina thin film as an etching protective layer avoids cumbersome processes such as polishing, alignment, bonding, and assembly. This invention provides a novel fabrication method and fundamental technical support for 2.5D heterogeneous integration technology.
[0014] The above embodiments use 2.5D silicon-based heterogeneous integration as an example to explain and illustrate the present invention, rather than to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims fall within the protection scope of the present invention.
Claims
1. A method for fabricating 2.5D heterogeneous integrated optical waveguides, comprising the following specific steps: 1) Prepare the wafer sample and clean it. Spin-coat photoresist onto the sample and use electron beam exposure and inductively coupled plasma etching to pattern and etch the structure of the corresponding material on the wafer sample to form the first material waveguide. 2) An aluminum oxide thin film with a thickness of 5~50 nm is deposited on the surface formed in step 1) by atomic layer deposition to form an aluminum oxide thin film layer; 3) Deposit other heterogeneous material layers on the surface of the alumina thin film formed in step 2) using chemical vapor deposition, physical vapor deposition, or sputtering. Spin coat photoresist on the surface a second time, and pattern the structure of the other heterogeneous materials by electron beam exposure and inductively coupled plasma etching to form a second material waveguide. When etching reaches the alumina thin film, the etching will stop until the unwanted other heterogeneous materials are completely etched away. 4) After the resist is stripped off, a heterogeneous integrated optical waveguide device structure is formed. Finally, a cladding layer is deposited on the surface of the entire structure as waveguide protection.
2. The fabrication method for 2.5D heterogeneous integrated optical waveguides according to claim 1, characterized in that: The 2.5D heterogeneous integration refers to the first material waveguide formed in step 1) and the second material waveguide formed in step 3) being on the same horizontal plane, that is, integrating other functional materials or devices onto the same substrate plane to achieve functional enhancement or expansion, and the different heterogeneous materials have different heights.
3. The fabrication method for 2.5D heterogeneous integrated optical waveguides according to claim 1 or 2, characterized in that: The first type of waveguide material is silicon (Si), silicon nitride (SiN), lithium niobate (LN), or a group III-V material.
4. The fabrication method for 2.5D heterogeneous integrated optical waveguides according to claim 3, characterized in that: The second type of waveguide material is silicon nitride (SiN), titanium dioxide (TiO2), glaze glass, or germanium (Ge).