A radiation-resistant photonic chip composite film structure

Abstract

This invention relates to a radiation-resistant composite film structure for photonic chips, belonging to the field of optoelectronic integration technology. From bottom to top, the structure includes a silicon substrate, a silicon dioxide cladding layer, an aluminum thin film, a silicon dioxide layer, a silicon strip waveguide / grating / silicon ridge waveguide / modulator / germanium-silicon detector, a silicon dioxide cladding layer, an aluminum thin film, a silicon dioxide layer, and a silicon nitride layer. This invention designs a composite film layer composed of multiple layers of aluminum thin film, silicon dioxide, and silicon nitride around a typical silicon-based optoelectronic chip. This effectively isolates charged particles, non-electron particles, and photons from the cosmic environment, primarily alpha particles, heavy ions, neutrons, X-rays, and gamma rays. It effectively protects passive and active devices within the silicon-based optoelectronic chip, including waveguides, gratings, modulators, and detectors, solving the problem of performance degradation of silicon-based optoelectronic chips due to radiation exposure in the cosmic environment.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic integration technology and relates to a radiation-resistant photonic chip composite film structure. Background Technology

[0002] Silicon-based optoelectronics is an emerging technology that integrates high-bandwidth, low-loss, and high-parallelism photonic devices with high-density, large-scale electronic devices using CMOS-compatible processes. It is considered one of the solutions to overcome the information bottlenecks of integrated circuit technology in the post-Moore's Law era. Silicon-based photonic chips have already been applied in data centers, autonomous driving, and biosensing. Their high integration and small size also suggest they may play a significant role in space scenarios such as satellite interconnects, inter-satellite communication, and space stations. However, conventional silicon-based optoelectronic devices are significantly affected by cosmic radiation. Passive devices exposed to long-term irradiation experience changes in refractive index, leading to alterations in the optical transfer function and performance degradation. Active devices exposed to irradiation exhibit effects such as changes in electron-hole pairs and carrier concentration, increasing detector dark current and reducing modulator bandwidth.

[0003] Therefore, this invention designs a radiation-resistant photonic chip composite film structure. By adding a composite film structure consisting of a silicon dioxide passivation layer, an aluminum thin film protective layer, and a silicon nitride protective layer to the conventional silicon-based optoelectronic process and film, it can effectively protect against X-rays, gamma rays, neutrons, protons, and alpha particles while remaining compatible with the original process. This reduces or even avoids ionization dose effects and electric displacement effects in silicon-based optoelectronic devices, thereby improving the reliability and durability of silicon-based optoelectronic chips in cosmic radiation environments. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a radiation-resistant photonic chip composite film structure to solve the problems of passive device wavelength drift, increased detector dark current, and reduced modulator bandwidth caused by cosmic radiation in conventional silicon-based optoelectronic devices. The composite film structure, composed of a silicon dioxide passivation layer, an aluminum thin film protective layer, and a silicon nitride protective layer, specifically protects against radiation factors such as X-rays, gamma rays, neutrons, protons, and alpha particles in outer space, thereby reducing or even avoiding ionization dose effects and electric displacement effects in silicon-based optoelectronic devices, and improving the reliability and durability of silicon-based optoelectronic chips in cosmic radiation environments.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A radiation-resistant photonic chip composite film structure includes:

[0007] silicon substrate;

[0008] A silicon dioxide cladding layer located on a silicon substrate;

[0009] A thin aluminum film protective layer located on the silica cladding;

[0010] A silicon dioxide layer located on top of the aluminum film protective layer;

[0011] Silicon strip waveguides, gratings, silicon ridge waveguides, modulators, and germanium-silicon detectors located on silicon dioxide layers;

[0012] Silicon dioxide cladding is located on silicon strip waveguides, gratings, silicon ridge waveguides, modulators, and germanium-silicon detectors;

[0013] A thin aluminum film protective layer located on the silica cladding;

[0014] A silicon dioxide layer located on top of the aluminum film protective layer;

[0015] A silicon nitride layer located on top of a silicon dioxide layer.

[0016] Furthermore, the silicon substrate is a silicon nitride on insulator substrate layer.

[0017] Furthermore, the silicon dioxide cladding is a low-refractive-index material used to confine the optical field in the silicon nitride waveguide layer.

[0018] Furthermore, the silicon nitride waveguide layer has a cross-sectional size of 150 nm × 800 nm, which is used to support single-mode transmission of visible light wavelengths from 380 nm to 740 nm.

[0019] Furthermore, the metasurface structure consists of periodic subwavelength-level holes etched onto a silicon nitride waveguide layer, used to achieve modulation of intensity, phase, and polarization characteristics in the visible light wavelength range.

[0020] Furthermore, the BCB bonding layer is used to bond and fix silicon nitride devices and gallium nitride devices, and is transparent to visible light wavelengths.

[0021] Furthermore, the silicon dioxide layer and silicon nitride layer can resist the electric displacement effect, and the aluminum thin film protective layer can resist the total ionization dose effect.

[0022] Furthermore, the composite film layer of aluminum thin film protective layer, silicon dioxide layer, and silicon nitride layer has windows specifically opened at the locations of devices such as gratings, modulators, and detectors that require windowing and electrode connections, so as to achieve large-area protection of the chip without affecting optical coupling and electrical performance.

[0023] The beneficial effects of this invention are as follows: by adding a composite film structure consisting of a silicon dioxide passivation layer, an aluminum thin film protective layer, and a silicon nitride protective layer to the conventional silicon-based optoelectronic process and film layer, it can effectively protect against X-rays, gamma rays, neutrons, protons, and alpha particles while maintaining compatibility with the original process. This reduces or even avoids ionization dose effects and electric displacement effects in silicon-based optoelectronic devices, thereby improving the reliability and durability of silicon-based optoelectronic chips in cosmic radiation environments.

[0024] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0026] Figure 1 This invention relates to a radiation-resistant photonic chip composite film structure.

[0027] Figure 2 This is a schematic diagram of the present invention used to protect a typical silicon-based optoelectronic microring;

[0028] Figure 3 This is a schematic diagram of a typical silicon-based optoelectronic modulator used in this invention;

[0029] Reference numerals: 101 - Silicon substrate of Example 1, 102 - Silicon dioxide cladding layer 1 of Example 1, 103 - Aluminum thin film 1 of Example 1, 104 - Silicon dioxide layer of Example 1, 105 - Silicon strip waveguide of Example 1, 106 - Grating of Example 1, 107 - Silicon ridge waveguide of Example 1, 108 - Modulator of Example 1, 109 - Germanium-silicon detector of Example 1, 110 - Silicon dioxide cladding layer 3 of Example 1, 111 - Aluminum thin film 2 of Example 1, 112 - Silicon dioxide layer 4 of Example 1, 113 - Silicon nitride layer of Example 1;

[0030] 201 - Example 2: Silicon substrate; 202 - Example 2: Silicon dioxide cladding layer 1; 203 - Example 2: Aluminum thin film 1; 204 - Example 2: Silicon dioxide layer; 205 - Example 2: Microring resonator; 206 - Example 2: Silicon dioxide cladding layer 3; 207 - Example 2: Aluminum thin film 2; 208 - Example 2: Silicon dioxide layer 4; 209 - Example 2: Silicon nitride layer.

[0031] 301 - Example 3: Silicon substrate; 302 - Example 3: Silicon dioxide cladding layer 1; 303 - Example 3: Aluminum thin film 1; 304 - Example 3: Silicon dioxide layer; 305 - Example 3: Modulator; 306 - Example 3: Silicon dioxide cladding layer 3; 307 - Example 3: Aluminum thin film 2; 308 - Example 3: Modulator traveling wave electrode; 309 - Example 3: Silicon dioxide layer 4; 310 - Example 3: Silicon nitride layer; 311 - Example 3: Opening. Detailed Implementation

[0032] 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 be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0033] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0034] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0035] Example 1

[0036] Please see Figure 1 ,like Figure 1As shown, a radiation-resistant photonic chip composite film structure includes, from bottom to top, a silicon substrate 101 (Example 1), a silicon dioxide cladding layer 102 (Example 1), an aluminum thin film 103 (Example 1), a silicon dioxide layer 2 104 (Example 1), a silicon strip waveguide 105 (Example 1), a grating 106 (Example 1), a silicon ridge waveguide 107 (Example 1), a modulator 108 (Example 1), a germanium-silicon detector 109 (Example 1), a silicon dioxide cladding layer 3 110 (Example 1), an aluminum thin film 2 111 (Example 1), a silicon dioxide layer 4 112 (Example 1), and a silicon nitride layer 113 (Example 1).

[0037] In this embodiment, the silicon substrate 101 is a silicon nitride-on-insulator substrate layer with a thickness of approximately 725 micrometers; the silicon dioxide cladding layer 102 has a refractive index of 1.44 and serves as a low-refractive-index material to confine the light field in the aluminum thin film 103, with an overall thickness of 5 micrometers; the aluminum thin film 103 has a cross-sectional size of 150 nanometers × 800 nanometers and can support single-mode transmission of visible light wavelengths from 380 nanometers to 740 nanometers; the silicon dioxide layer 104 is a periodic subwavelength-level hole etched on the aluminum thin film 103 to achieve the modulation of intensity, phase, and polarization characteristics in the visible light wavelength range, with a characteristic size of 100 nanometers, which is smaller than the shortest wavelength to be modulated, 380 nanometers; the BCB bonding layer silicon strip waveguide 105 is used to realize the bonding and fixation of silicon nitride devices and gallium nitride devices, with a thickness of 150 nanometers and is transparent to the visible light wavelength range.

[0038] This embodiment presents a radiation-resistant photonic chip composite film structure. By adding a composite film structure consisting of a silicon dioxide passivation layer, an aluminum thin film protective layer, and a silicon nitride protective layer to the conventional silicon-based optoelectronic process and film, it can effectively protect against X-rays, gamma rays, neutrons, protons, and alpha particles while remaining compatible with the original process. This reduces or even avoids ionization dose effects and electric displacement effects in silicon-based optoelectronic devices, thereby improving the reliability and durability of silicon-based optoelectronic chips in cosmic radiation environments.

[0039] In this embodiment, silicon substrate 101 is a silicon substrate with a thickness of approximately 700 micrometers; silicon dioxide cladding layer 102 has a refractive index of 1.44 and a thickness of 2 micrometers; aluminum thin film 103 has a thickness of approximately 2 micrometers; silicon dioxide layer 104 has a refractive index of 1.44 and a thickness of 3 micrometers; silicon strip waveguide 105, grating 106, silicon ridge waveguide 107, modulator 108, and germanium-silicon detector 109 are basic passive and active devices in silicon-based optoelectronic chips, protected by a composite film layer consisting of aluminum thin film 103, silicon dioxide layer 104, silicon dioxide cladding layer 110, aluminum thin film 111, silicon dioxide layer 112, and silicon nitride layer 113, to avoid the influence of cosmic rays and particles on the refractive index of the device material, PN particle injection concentration, and defects in the material itself. The silicon dioxide and silicon nitride layers can resist the electric displacement effect, while the aluminum thin film layer is more resistant to the total ionization dose effect. By constructing the composite film layer, the overall radiation resistance of the chip is greatly improved.

[0040] Example 1: Silicon dioxide cladding layer 3 (110) has a refractive index of 1.44 and a thickness of 3-5 micrometers; Example 1: Aluminum thin film 2 (111) has a thickness of 2 micrometers; Example 1: Silicon dioxide layer 4 (112) has a refractive index of 1.44 and a thickness of 2 micrometers; Example 1: Silicon nitride layer 113 has a thickness of 300 nanometers. The composite film layer of Example 1: Aluminum thin film 2 (111), Example 1: Silicon dioxide layer 4 (112), and Example 1: Silicon nitride layer 113 is used to selectively open windows at the locations of devices such as gratings, modulators, and detectors that require windowing and electrode connections, achieving large-area protection of the chip without affecting optical coupling and electrical performance.

[0041] Example 2

[0042] This embodiment presents a radiation-resistant photonic chip composite film structure for protecting a typical silicon-based optoelectronic microring resonator. This passive device has no structure exposed in the vertical direction; therefore, the protection method of this invention provides full coverage. The composite film structure, composed of a silicon dioxide passivation layer, an aluminum thin film protective layer, and a silicon nitride protective layer, can effectively reduce or even avoid ionization dose effects and electric displacement effects in silicon-based optoelectronic devices, maintaining the wavelength stability and device consistency of the microring resonator.

[0043] In Example 2, the silicon substrate 201 is a silicon substrate with a thickness of approximately 700 micrometers; the silicon dioxide cladding layer 202 has a refractive index of 1.44 and a thickness of 2 micrometers; the aluminum thin film 203 has a thickness of approximately 2 micrometers; the silicon dioxide layer 204 has a refractive index of 1.44 and a thickness of 3 micrometers; the microring resonator 205 is a typical refractive index-sensitive and wavelength-sensitive filter device; the silicon dioxide cladding layer 206 has a refractive index of 1.44 and a thickness of 3 to 5 micrometers; the aluminum thin film 207 has a thickness of 2 micrometers; the silicon dioxide layer 208 has a refractive index of 1.44 and a thickness of 2 micrometers; and the silicon nitride layer 209 has a thickness of 300 nanometers. The composite film layer of the aluminum thin film 207, silicon dioxide layer 208, and silicon nitride layer 209 in Example 2 completely covers the substrate.

[0044] Example 3

[0045] This embodiment presents a radiation-resistant photonic chip composite film structure for protecting a typical silicon-based optoelectronic modulator, comprising: a silicon substrate 301 (Example 3), a silicon dioxide cladding layer 302 (Example 3), an aluminum thin film 303 (Example 3), a silicon dioxide layer 304 (Example 3), a modulator 305 (Example 3), a silicon dioxide cladding layer 306 (Example 3), an aluminum thin film 307 (Example 3), a traveling-wave electrode for the modulator 308 (Example 3), a silicon dioxide layer 309 (Example 3), a silicon nitride layer 310 (Example 3), and an opening 311 (Example 3). In this device, the aluminum thin film 307 (Example 3) and the traveling-wave electrode for the modulator 308 are on the same physical layer. Therefore, a gap of 50 micrometers or more is left between the traveling-wave electrode for the modulator 308 and the aluminum thin film protective layer to avoid electrical signal crosstalk. Meanwhile, to provide space for the modulator to connect to the outside world, openings are made in the silicon dioxide layer 309 and silicon nitride layer 310 above the traveling wave electrode 308 of the modulator in Embodiment 3, reserving positions for gold wire bonding and encapsulation. Therefore, this embodiment only makes openings in places where electrical connections are rarely needed on the chip, while still retaining the composite film layer structure composed of aluminum thin film, silicon dioxide passivation layer, and silicon nitride protective layer in most areas. This can effectively reduce or even avoid ionization dose effect and electric displacement effect in silicon-based optoelectronic devices, maintaining the bandwidth and stability of the electro-optic modulator.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A radiation-resistant photonic chip composite film structure, characterized in that: include: silicon substrate; A silicon dioxide cladding layer located on a silicon substrate; A thin aluminum film protective layer located on the silica cladding; A silicon dioxide layer located on top of the aluminum thin film protective layer; Silicon strip waveguides, gratings, silicon ridge waveguides, modulators, and germanium-silicon detectors located on silicon dioxide layers; Silicon dioxide cladding is located on silicon strip waveguides, gratings, silicon ridge waveguides, modulators, and germanium-silicon detectors; A thin aluminum film protective layer located on the silica cladding; A silicon dioxide layer located on top of the aluminum thin film protective layer; A silicon nitride layer located on top of a silicon dioxide layer; The composite film layer consisting of aluminum thin film protective layer, silicon dioxide layer, and silicon nitride layer has windows specifically designed for the locations of devices such as gratings, modulators, and detectors that require windowing and electrode connections. This achieves large-area protection for the chip without affecting optical coupling and electrical performance.

2. The radiation-resistant photonic chip composite film structure according to claim 1, characterized in that: The silicon substrate is a silicon nitride on insulator substrate layer.

3. The radiation-resistant photonic chip composite film structure according to claim 1, characterized in that: The silicon dioxide layer and silicon nitride layer can resist the electric displacement effect, and the aluminum thin film protective layer can resist the total ionization dose effect.

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