Waveguide coupling photoelectric detector and preparation method and application thereof
By fabricating waveguide-coupled photodetectors on silicon photonics or CMOS platforms and optimizing the region definition and material growth process, the problems of difficult Sn source introduction and thermal budget conflict were solved, achieving selective growth of high-quality Ge1-xSnx materials, improving the reliability and integrability of the devices, and making them suitable for near-infrared to mid-infrared photonic integrated systems.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-25
- Publication Date
- 2026-04-17
AI Technical Summary
In existing technologies, it is difficult to introduce Sn sources into current mature silicon photonics platforms. The fabrication process of high-quality Ge1-xSnx materials conflicts with the thermal budget of CMOS back-end processes, resulting in complex processes, low yields, and difficulty in fabricating high-quality waveguide-coupled photodetectors.
Waveguide-coupled photodetectors are fabricated on silicon photonics or CMOS platforms. By defining regions, controlling interfaces, and optimizing material growth processes, Ge1-xSnx absorption layers can be selectively deposited or epitaxially grown to avoid material failure caused by high-temperature epitaxy and protect existing silicon photonic waveguides and dielectric layers from damage.
The efficient integration of Ge1-xSnx materials with a silicon-based photonics platform has been achieved. The resulting waveguide-coupled photodetector has a compact structure, a wide wavelength coverage, and high process compatibility, making it suitable for near-infrared to mid-infrared photonic integrated systems.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of optoelectronic materials and devices technology, specifically relating to a waveguide-coupled photodetector, its fabrication method, and its application. Background Technology
[0002] With the rapid development of information technologies such as big data and artificial intelligence, the demand for high speed, low power consumption, and high integration in information processing systems is constantly increasing. Optoelectronic integration technology, with its high speed, wide bandwidth, and low power consumption, has become an important direction for achieving efficient information interconnection. Silicon-based optoelectronic integration, with its CMOS process compatibility and low-cost scalable manufacturing potential, is one of the most promising technological paths.
[0003] Silicon-based photodetectors are key components in silicon photonics systems. 1-x Sn x As a novel silicon-based group IV compound semiconductor, Ge possesses advantages such as tunable bandgap, high absorption coefficient, and good CMOS process compatibility. 1-x Sn x The band gap of the material decreases with increasing Sn composition, and the absorption edge redshifts. This allows the detector to cover not only traditional communication bands (such as O, C, and L bands) but also extend to the mid-infrared band of 2-4µm, meeting the needs of emerging applications such as spectral sensing and free-space communication. Simultaneously, the introduction of Sn composition effectively improves the material's absorption efficiency and enhances carrier mobility, facilitating the development of photodetectors with higher response and higher bandwidth. Depending on the light incidence method, photodetectors can be divided into two categories: surface-incident and waveguide-coupled. Compared to surface-incident structures, waveguide-coupled detectors are more suitable for on-chip integration, enabling compact layouts; furthermore, their light propagation direction is perpendicular to the carrier transport direction, helping to achieve high bandwidth performance while maintaining high responsivity.
[0004] Currently, high-quality Ge is being achieved on silicon photonics or CMOS platforms. 1-x Sn x Waveguide-coupled detectors still face multiple challenges. First, introducing Sn sources into current mature silicon photonics platforms is difficult, hindering the large-scale fabrication of devices; second, high-quality Ge... 1-x Sn x The fabrication process of materials often conflicts with the thermal budget of CMOS back-end processes. Furthermore, the coupling structure between heterogeneous materials and silicon waveguides is prone to mode mismatch and requires high process alignment accuracy, leading to complex processes and low yields. Therefore, this study investigates the fabrication of high-quality Ge materials while maintaining CMOS thermal budget compatibility. 1-x Sn x Developing an absorption layer and constructing a waveguide-coupled photodetector suitable for the near-infrared to mid-infrared bands are key technical issues that urgently need to be addressed. Summary of the Invention
[0005] This application provides a waveguide-coupled photodetector, its fabrication method, and its application, aiming to solve the difficulties in introducing Sn sources into current mature silicon photonic platforms and to achieve high-quality Ge 1-x Sn x The material fabrication process often conflicts with the thermal budget of CMOS back-end processes, resulting in complex processes and low yields.
[0006] The first aspect of this application provides a waveguide-coupled photodetector, including a substrate layer, a buffer layer, and a Ge layer. 1-x Sn x Absorption layer, second passivation layer, and second electrode; The substrate layer includes a substrate layer, an optical waveguide layer, a first passivation layer, and a first electrode. The substrate layer, the optical waveguide layer, and the first passivation layer are stacked from bottom to top. The top of the first passivation layer is provided with two electrode holes. The first electrode is disposed above the first passivation layer. There are two first electrodes. The two first electrodes are electrically connected to the optical waveguide layer through the two electrode holes at the top of the first passivation layer, respectively. The first passivation layer has a hollow region to expose part of the optical waveguide layer, the buffer layer, and the Ge 1- x Sn x An absorption layer and a second passivation layer are sequentially disposed from bottom to top in the hollow region of the first passivation layer, and the buffer layer and the optical waveguide layer are in contact. The second passivation layer covers the buffer layer and the Ge layer. 1-x Sn x Absorption layer; An electrode hole is provided at the top of the second passivation layer, and the second electrode is located above the second passivation layer, connecting to Ge through the electrode hole at the top of the second passivation layer. 1-x Sn x Absorber layer electrical connection; Where: X takes the value 0 < x ≤ 0.30.
[0007] According to some embodiments of the waveguide-coupled photodetector described in this application, the substrate layer includes an SOI substrate, a silicon substrate, or a silicon-on-insulator substrate.
[0008] According to some embodiments of the waveguide-coupled photodetector described in this application, the optical waveguide layer includes a waveguide and a mesa structure; the optical waveguide layer includes silicon and / or silicon nitride.
[0009] According to some embodiments of the waveguide-coupled photodetector described in this application, the buffer layer includes a semiconductor layer; preferably, the buffer layer includes one or more of a germanium layer, a silicon-germanium alloy layer, and a silicon-germanium-tin alloy layer.
[0010] According to some embodiments of the waveguide-coupled photodetector described in this application, the first passivation layer and the second passivation layer each independently comprise silicon oxide and / or silicon nitride.
[0011] According to some embodiments of the waveguide-coupled photodetector described in this application, the first electrode and the second electrode each independently include at least one of a Ni electrode, a Cr electrode, a Ti electrode, an Al electrode, and an Au electrode.
[0012] A second aspect of this application provides a method for fabricating the waveguide-coupled photodetector described in the first aspect of this application, comprising the following steps: (1) An optical waveguide layer is formed on the substrate layer, a first passivation layer with two electrode holes is formed on the optical waveguide layer, a first electrode is fabricated on the top of the first passivation layer and electrically connected to the optical waveguide layer through the electrode holes to obtain the substrate layer. (2) A first passivation layer is formed on top of the first passivation layer to seal the first electrode; (3) A hollow region is formed on the first passivation layer to expose the optical waveguide layer in the hollow region; and the exposed optical waveguide layer is processed to meet the requirements of epitaxial growth. (4) A buffer layer is formed on the surface of the exposed optical waveguide layer, and Ge is epitaxially grown on the buffer layer. 1-x Sn x Absorption layer; and in Ge 1-x Sn x A second passivation layer is formed on the absorption layer, and the second passivation layer covers the buffer layer and Ge. 1-x Sn x Absorption layer; (5) An electrode hole is made on the top of the first passivation layer to expose the first electrode, and the first electrode is made up to the top of the first passivation layer. (6) An electrode hole is formed on top of the second passivation layer, and a second electrode is formed so that it passes through the electrode hole and interacts with Ge. 1- x Sn x The absorption layer is electrically connected, where the value of X is 0 < x ≤ 0.30.
[0013] According to some embodiments of the waveguide-coupled photodetector fabrication method described in this application, the method for forming the electrode hole includes: fabricating the electrode hole on top of a first passivation layer or a second passivation layer by exposure and inductively coupled plasma etching.
[0014] According to some embodiments of the waveguide-coupled photodetector fabrication method described in this application, the method for forming the first electrode and the second electrode includes: evaporating metal in the first electrode hole or the second electrode hole using electron beam evaporation to obtain the first electrode or the second electrode.
[0015] According to some embodiments of the waveguide-coupled photodetector fabrication method described in this application, the metal includes at least one of Ni, Cr, Ti, Al, and Au.
[0016] According to some embodiments of the waveguide-coupled photodetector fabrication method described in this application, in step (1), the optical waveguide layer is formed by exposure and inductively coupled plasma etching.
[0017] According to some embodiments of the waveguide-coupled photodetector fabrication method described in this application, the first passivation layer is formed by thermal oxidation or chemical vapor deposition.
[0018] According to some embodiments of the waveguide-coupled photodetector fabrication method described in this application, in step (2), the method of creating a hollow region on the first passivation layer includes exposure and inductively coupled plasma etching.
[0019] According to some embodiments of the waveguide-coupled photodetector fabrication method described in this application, in step (2), the method for processing the optical waveguide layer includes plasma processing and / or wet chemical processing.
[0020] According to some embodiments of the waveguide-coupled photodetector fabrication method described in this application, the method for forming the buffer layer includes chemical vapor deposition.
[0021] According to some embodiments of the fabrication method of the waveguide-coupled photodetector described in this application, the epitaxial growth of Ge 1-x Sn x Methods for creating an absorption layer include chemical vapor deposition, wherein the epitaxial growth of Ge 1-x Sn x The temperature of the absorption layer is ≤400℃.
[0022] The third aspect of this application provides an application of the waveguide-coupled photodetector described in the first aspect of this application or the waveguide-coupled photodetector prepared by the method described in the second aspect of this application in near-infrared or mid-infrared optical detection.
[0023] According to some embodiments of the application described in this application, the waveguide-coupled photodetector is used in optical detection in the 1.3µm to 4µm near-infrared or mid-infrared band.
[0024] The beneficial effects of this application include: the waveguide-coupled photodetector described in this application completes device integration without damaging the existing silicon waveguide, dielectric layer, and interconnect structure, realizing Ge 1-x Sn xThe efficient integration of materials with a silicon-based photonics platform results in a waveguide-coupled photodetector with advantages such as compact structure, wide wavelength coverage, and high process compatibility, which can be widely used in silicon-based near-infrared to mid-infrared photonic integrated systems.
[0025] The fabrication method of the waveguide-coupled photodetector described in this application optimizes the fabrication process through region definition, interface control, and material growth process, enabling Ge... 1-x Sn x This method enables selective deposition or epitaxial growth under CMOS back-end thermal budget conditions, avoiding material failure problems caused by traditional high-temperature epitaxy and improving device reliability and integrability. The method described in this application enables Ge... 1-x Sn x It forms only at predetermined locations, while protecting the existing silicon waveguide, dielectric layer, and metal interconnect structure from damage, avoiding disruption of existing silicon photonics process structures, and improving overall process compatibility. Attached Figure Description
[0026] Figure 1 This is a schematic diagram of the waveguide-coupled photodetector described in this application. The direction of light propagation in the waveguide is parallel to the x-axis in the device's coordinate system. Figures 2a-2h This is a schematic flowchart of the waveguide-coupled photodetector fabrication method according to an embodiment of this application; Figure 2a To prepare the base layer; Figure 2b To seal the first electrode; Figure 2c To create a hollow region on the first passivation layer; Figure 2d To prepare a buffer layer; Figure 2e To prepare Ge 1-x Sn x Absorption layer; Figure 2f To prepare the second passivation layer; Figure 2g To prepare electrode holes; Figure 2h To prepare the first electrode and the second electrode.
[0027] In the figure: 100. Substrate layer; 200. Optical waveguide layer; 300. First passivation layer; 400. Buffer layer; 500. Ge 1-x Sn x Absorbing layer; 600. First electrode; 700. Second passivation layer; 800. Second electrode. Detailed Implementation
[0028] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.
[0029] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0030] This application provides a waveguide-coupled photodetector, including a substrate layer, a buffer layer, and a Ge layer. 1-x Sn x Absorption layer, second passivation layer, and second electrode; The substrate layer includes a substrate layer, an optical waveguide layer, a first passivation layer, and a first electrode. The substrate layer, the optical waveguide layer, and the first passivation layer are stacked from bottom to top. The top of the first passivation layer is provided with two electrode holes. The first electrode is disposed above the first passivation layer. There are two first electrodes. The two first electrodes are electrically connected to the optical waveguide layer through the two electrode holes at the top of the first passivation layer, respectively. The first passivation layer has a hollow region to expose part of the optical waveguide layer, the buffer layer, and the Ge 1- x Sn x An absorption layer and a second passivation layer are sequentially disposed from bottom to top in the hollow region of the first passivation layer, and the buffer layer and the optical waveguide layer are in contact. The second passivation layer covers the buffer layer and the Ge layer. 1-x Sn x Absorption layer; An electrode hole is provided at the top of the second passivation layer, and the second electrode is located above the second passivation layer, connecting to Ge through the electrode hole at the top of the second passivation layer. 1-x Sn x Absorber layer electrical connection (e.g.) Figure 1 As shown, the direction of light propagation in the waveguide is parallel to the x-axis in the device coordinate system, where the value of X is 0 < x ≤ 0.30.
[0031] The waveguide-coupled photodetector described in this application forms a Ge-type semiconductor material in a predetermined region on a substrate with a partially completed silicon photonics or CMOS process structure through steps such as region selection, interface modulation, and semiconductor material growth. 1-x Sn xLight-absorbing materials. By introducing interface treatments and material control mechanisms suitable for back-end processes, high-quality GeO materials were achieved while meeting the thermal budget of CMOS back-end processes. 1-x Sn x Selective growth was used to construct a photoelectric detection structure that is highly coupled with silicon waveguide.
[0032] The waveguide-coupled photodetector described in this application achieves device integration without damaging the existing silicon waveguide, dielectric layer, and interconnect structure, realizing Ge 1-x Sn x The efficient integration of materials with a silicon-based photonics platform results in a waveguide-coupled photodetector with advantages such as compact structure, wide wavelength coverage, and high process compatibility, which can be widely used in silicon-based near-infrared to mid-infrared photonic integrated systems.
[0033] In some embodiments of this application, the substrate layer includes an SOI substrate, a silicon substrate, or a silicon-on-insulator substrate.
[0034] In some embodiments of this application, the optical waveguide layer includes a waveguide and a mesa structure; the optical waveguide layer includes silicon and / or silicon nitride.
[0035] In some embodiments of this application, the buffer layer includes a semiconductor layer.
[0036] In some embodiments of this application, the buffer layer includes one or more of a germanium layer, a silicon-germanium alloy layer, and a silicon-germanium-tin alloy layer.
[0037] In some embodiments of this application, the first passivation layer and the second passivation layer each independently comprise silicon oxide and / or silicon nitride.
[0038] In some embodiments of this application, the first electrode and the second electrode each independently include at least one of a Ni electrode, a Cr electrode, a Ti electrode, an Al electrode, and an Au electrode.
[0039] This application also provides a method for fabricating the waveguide-coupled photodetector described in the first aspect of this application, comprising the following steps: (1) An optical waveguide layer is formed on the substrate layer, a first passivation layer with two electrode holes is formed on the optical waveguide layer, a first electrode is fabricated on the top of the first passivation layer and electrically connected to the optical waveguide layer through the electrode holes to obtain the substrate layer. (2) A first passivation layer is formed on top of the first passivation layer to seal the first electrode; (3) A hollow region is formed on the first passivation layer to expose the optical waveguide layer in the hollow region; and the exposed optical waveguide layer is processed to meet the requirements of epitaxial growth. (4) A buffer layer is formed on the surface of the exposed optical waveguide layer, and Ge is epitaxially grown on the buffer layer. 1-x Sn x Absorption layer; and in Ge 1-x Sn x A second passivation layer is formed on the absorption layer, and the second passivation layer covers the buffer layer and Ge. 1-x Sn x Absorption layer; (5) An electrode hole is made on the top of the first passivation layer to expose the first electrode, and the first electrode is made up to the top of the first passivation layer. (6) An electrode hole is formed on top of the second passivation layer, and a second electrode is formed so that it passes through the electrode hole and interacts with Ge. 1- x Sn x The absorption layer is electrically connected, where the value of X is 0 < x ≤ 0.30.
[0040] The fabrication method of the waveguide-coupled photodetector described in this application optimizes the fabrication process through region definition, interface control, and material growth process, enabling Ge... 1-x Sn x This method enables selective deposition or epitaxial growth under CMOS back-end thermal budget conditions, avoiding material failure problems caused by traditional high-temperature epitaxy and improving device reliability and integrability. The method described in this application enables Ge... 1-x Sn x It forms only at predetermined locations, while protecting the existing silicon waveguide, dielectric layer, and metal interconnect structure from damage, avoiding disruption of existing silicon photonics process structures, and improving overall process compatibility.
[0041] The waveguide-coupled photodetector described in this application introduces a Sn-component-tunable Ge... 1-x Sn x The material enables effective optical detection in the near-infrared to mid-infrared band of the silicon photonics platform, laying the foundation for the development of next-generation silicon photonics communication, near-infrared to mid-infrared detection and on-chip spectroscopy.
[0042] In some embodiments of this application, the method for forming the electrode hole includes: preparing the electrode hole on top of a first passivation layer or a second passivation layer by exposure and inductively coupled plasma etching.
[0043] In some embodiments of this application, the method for forming the first electrode and the second electrode includes: evaporating metal in the first electrode hole or the second electrode hole using electron beam evaporation to obtain the first electrode or the second electrode.
[0044] In some embodiments of this application, the metal includes at least one of Ni, Cr, Ti, Al, and Au.
[0045] In some embodiments of this application, in step (1), the optical waveguide layer is formed by means of exposure and inductively coupled plasma etching to prepare the optical waveguide layer.
[0046] In some embodiments of this application, the first passivation layer is formed by thermal oxidation or chemical vapor deposition.
[0047] In some embodiments of this application, the method of creating a hollow region on the first passivation layer in step (2) includes exposure and inductively coupled plasma etching.
[0048] In some embodiments of this application, the method for processing the optical waveguide layer in step (2) includes plasma treatment and / or wet chemical treatment.
[0049] In some embodiments of this application, the method for forming the buffer layer includes chemical vapor deposition.
[0050] In some embodiments of this application, the epitaxial growth of Ge 1-x Sn x Methods for creating an absorption layer include chemical vapor deposition, wherein the epitaxial growth of Ge 1-x Sn x The temperature of the absorption layer is ≤400℃; for example, 300℃, 320℃, 350℃, 380℃, 400℃, etc., and the vacuum degree is ≤10. -6 Pa. The epitaxial growth is selective epitaxy to ensure Ge 1-x Sn x It grows only in the hollow region, without damaging the waveguide, dielectric layer or metal interconnect structure already formed in the silicon photonics platform.
[0051] This application also provides an application of the waveguide-coupled photodetector described in the first aspect of this application or the waveguide-coupled photodetector prepared by the method described in the second aspect of this application in near-infrared or mid-infrared optical detection. It can be applied to optical communication systems, spectral sensing, or free-space communication, etc.
[0052] In some embodiments of this application, the waveguide-coupled photodetector is used in optical detection in the near-infrared or mid-infrared band of 1.3um to 4um, such as 1.31um, 1.55um, 1.6um, 1.8um, 2.0um, 2.5um, 2.8um, 3.0um, 3.5um, 3.7um, 4.0um, etc.
[0053] The technical solution of this application will be further described below with reference to specific embodiments.
[0054] Example 1 A method for fabricating a waveguide-coupled photodetector includes the following steps: (1) Preparation of the base layer like Figure 2a As shown: A silicon optical waveguide layer is prepared on an SOI substrate by exposure and inductively coupled plasma etching. A silicon oxide first passivation layer is formed on the silicon optical waveguide layer by chemical vapor deposition. Two first electrode holes are formed on the silicon oxide first passivation layer by exposure and inductively coupled plasma etching. Metals Ni and Al are evaporated into the two first electrode holes to the top of the first passivation layer by electron beam evaporation to form the first electrode. The first electrode is electrically connected to the silicon optical waveguide layer to obtain the substrate layer. (2) Seal the first electrode like Figure 2b As shown: A 200nm thick first passivation layer of silicon oxide is formed on top of the first passivation layer of silicon oxide by chemical vapor deposition to seal the first electrode; (3) Create a hollow region on the first passivation layer like Figure 2c As shown: A hollow region pattern is formed on the first passivation layer of silicon oxide using exposure technology, and then a hollow region is formed on the first passivation layer of silicon oxide using inductively coupled plasma etching process, so that the silicon optical waveguide layer is exposed in the hollow region. The length of the hollow region is 20μm and the width is 6μm; and the silicon optical waveguide layer is treated with plasma treatment method to meet the requirements of epitaxial growth. (4) Forming a buffer layer like Figure 2d As shown: Ultra-high vacuum chemical vapor deposition (UHV / CVD) is used at temperatures below 10... -6 (Under the pressure of Pa), a silicon-germanium alloy buffer layer 400 is first grown on the surface of the silicon optical waveguide layer exposed in the hollow region of the first passivation layer of silicon oxide. (5) Formation of Ge 1-x Sn x Absorption layer like Figure 2e As shown: Ultra-high vacuum chemical vapor deposition (UHV / CVD) is used at temperatures below 10... -6 Ge was prepared on a buffer layer under pressure of Pa and temperature of 400℃. 1-x Sn x Absorption region; (6) Formation of a second passivation layer like Figure 2f As shown: Plasma chemical vapor deposition was used to deposit Ge 1-x Sn x A 200 nm thick silicon oxide second passivation layer is deposited on the absorption layer, so that the silicon oxide second passivation layer covers the buffer layer and Ge. 1-x Sn x Absorption layer; (7) Preparation of electrode holes like Figure 2g As shown: an electrode opening pattern is formed on the top of the first passivation layer of silicon oxide using exposure technology, and then an electrode hole is made at the electrode opening using inductively coupled plasma etching process to expose the first electrode; an electrode opening is formed on the top of the second passivation layer using exposure technology, and then an electrode hole is made at the electrode opening using inductively coupled plasma etching process. (8) Electrode preparation like Figure 2h As shown: Electron beam evaporation technology is used to continue evaporating metallic Ni in the electrode holes of the first passivation layer, bringing the first electrode to the top of the first passivation layer; electron beam evaporation technology is also used to evaporate metallic Ni in the electrode holes of the second passivation layer to form a second electrode, bringing it to the top of the second passivation layer, so that the second electrode passes through the electrode holes and interacts with Ge. 1-x Sn x The absorption layer is electrically connected to fabricate a waveguide-coupled photodetector, where X = 0.05.
[0055] Example 2 The difference between the fabrication method of the waveguide-coupled photodetector in Example 2 and that in Example 1 is that, during the fabrication process of the waveguide-coupled photodetector in Example 2, Ge is formed. 1-x Sn x The absorption layer is deposited at a temperature of 300℃ using ultra-high vacuum chemical vapor deposition.
[0056] Example 3 The fabrication method of the waveguide-coupled photodetector described in Example 3 differs from that in Example 1 only in that, during the fabrication process of the waveguide-coupled photodetector described in Example 3, Ge is formed. 1-x Sn x The absorption layer is deposited at a temperature of 200℃ using ultra-high vacuum chemical vapor deposition.
[0057] Example 4 The difference between the fabrication method of the waveguide-coupled photodetector in Example 4 and that in Example 1 is that the only difference is that Ge is formed during the fabrication process of the waveguide-coupled photodetector in Example 4. 1-x Sn x The absorption layer is deposited at a temperature of 500℃ using ultra-high vacuum chemical vapor deposition.
[0058] Comparative Example 1 The only difference between the fabrication method of the waveguide-coupled photodetector in Comparative Example 1 and that in Example 1 is that Ge is used instead of Ge. 1-x Sn x An absorption layer is formed.
[0059] Performance Study of Waveguide Coupled Photodetectors as Described in Examples 1-4 and Comparative Example 1 of this Application Research Methods: The waveguide-coupled photodetectors described in Examples 1-4 and Comparative Example 1 of this application were characterized under the same device structure design and the same test conditions.
[0060] The waveguide-coupled photodetectors described in Examples 1-4 and Comparative Example 1 of this application are characterized under the same device structure design and simulation conditions. By setting parameters such as light source, simulation area, and device structure, the energy distribution of incident light in the absorption layer region of the waveguide-coupled photodetector is calculated, and the effective light absorption rate of the absorption layer of the waveguide-coupled photodetector at a specific wavelength is obtained.
[0061] The effective light absorption rate of the absorption layer of the waveguide-coupled photodetector described in Embodiments 1-4 of this application in the 2µm band is shown in Table 1.
[0062] Table 1
[0063] As can be seen from Table 1: The waveguide-coupled photodetectors described in Examples 1-4 of this application epitaxially shape Ge using an ultra-high vacuum chemical vapor deposition method. 1-x Sn x The growth temperature of the material affects the optoelectronic properties and material quality characteristics of the device.
[0064] When the epitaxial temperature is too low (as in Example 3), although it is beneficial for the introduction of Sn and thermal budget control, the material crystal quality is affected to some extent, and additional defects may be introduced. At the same time, because the material growth rate is slower at lower temperatures, the Ge1-xSnx absorber layer may be too thin, resulting in poor absorption efficiency, which will adversely affect the device performance.
[0065] When the epitaxial temperature is too high (as in Example 4), although it helps to improve the crystal growth kinetics, the Sn composition may become unstable and Sn segregation may occur at higher temperatures, which will affect the quality of the material crystal. At the same time, the higher temperature will have a thermal effect on the completed silicon photonics or metal structure, leading to device failure and being detrimental to CMOS back-end process compatibility.
[0066] In comparison, the epitaxial temperature ranges used in Examples 1 and 2 demonstrate a better overall effect in terms of material quality, device performance, and CMOS back-end thermal budget, and the devices have more stable photoresponse characteristics and lower process risks.
[0067] Optical responsivity study of the waveguide-coupled photodetector described in Example 1 and the waveguide-coupled photodetector described in Comparative Example 1 of this application. Assuming that the photogenerated carriers in the photoelectric testing system can be completely collected, and neglecting carrier recombination and transmission losses, the theoretical responsivity of the waveguide-coupled photodetector can be estimated using the standard photodetector responsivity formula R = ηq / hυ. Here, R is the responsivity, η is the external quantum efficiency of the photoelectric testing system (in this case, the effective light absorption rate under ideal conditions), q is the electron charge of the photoelectric testing system, and hυ is the energy of a single photon in the photoelectric testing system. Therefore, under simulated ideal conditions, the responsivity is directly proportional to the effective light absorption rate.
[0068] The effective light absorption rate and photoresponsivity results of the waveguide-coupled photodetector described in Embodiment 1 and the waveguide-coupled photodetector described in Comparative Example 1 are shown in Table 2.
[0069] Table 2
[0070] As shown in Table 2, the device using Ge as the absorption layer in Comparative Example 1 exhibits a certain optical response in the near-infrared band, but its response capability in the long-wavelength direction is limited, and the detectable wavelength range of the device is relatively narrow. As shown in Table 2, at a wavelength of 1.62 μm, the effective light absorption rate of the absorption layer of the device using Ge as the absorption layer is 35%, with a theoretical optical responsivity of 0.27 A / W, while the effective light absorption rate of the absorption layer of the device using GeSn as the absorption layer is 95%, with a theoretical optical responsivity of 0.73 A / W. At a wavelength of 2 μm, the effective light absorption rate of the absorption layer of the device using Ge as the absorption layer is 1.4%, with a theoretical optical responsivity of 0.009 A / W, while the effective light absorption rate of the absorption layer of the device using GeSn as the absorption layer is 74%, with a theoretical optical responsivity of 0.46 A / W. It can be concluded that using GeSn as the absorption layer can effectively improve the light absorption of the device, thereby increasing the optical responsivity.
[0071] In summary, this application describes the epitaxial growth of Ge on a substrate with an already completed silicon photonics or CMOS process structure, while meeting the CMOS back-end thermal budget. 1-x Sn x An absorption layer was used to fabricate a waveguide-coupled photodetector. The method achieved a good balance between material growth temperature, device performance, and process compatibility, validating the feasibility and technical advantages of the invention.
[0072] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.
Claims
1. A waveguide-coupled photodetector, comprising: including a base layer, a buffer layer, Ge 1-x Sn x absorbing layer, a second passivation layer, and a second electrode The substrate layer includes a substrate layer, an optical waveguide layer, a first passivation layer, and a first electrode. The substrate layer, the optical waveguide layer, and the first passivation layer are stacked from bottom to top. The top of the first passivation layer is provided with two electrode holes. The first electrode is disposed above the first passivation layer. There are two first electrodes. The two first electrodes are electrically connected to the optical waveguide layer through the two electrode holes at the top of the first passivation layer, respectively. The first passivation layer has a hollow region to expose part of the optical waveguide layer, the buffer layer, and the Ge 1-x Sn x An absorption layer and a second passivation layer are sequentially disposed from bottom to top in the hollow region of the first passivation layer, and the buffer layer and the optical waveguide layer are in contact. The second passivation layer covers the buffer layer and the Ge layer. 1-x Sn x Absorption layer; An electrode hole is provided at the top of the second passivation layer, and the second electrode is located above the second passivation layer, connecting to Ge through the electrode hole at the top of the second passivation layer. 1-x Sn x Absorber layer electrical connection; Where: X takes the value 0 < x ≤ 0.
30.
2. The waveguide-coupled photodetector of claim 1, wherein, The substrate layer includes an SOI substrate, a silicon substrate, or a silicon-on-insulator substrate. And / or, the optical waveguide layer includes a waveguide and a mesa structure; the optical waveguide layer includes silicon and / or silicon nitride; And / or, the buffer layer includes a semiconductor layer; preferably, the buffer layer includes one or more of a germanium layer, a silicon-germanium alloy layer, and a silicon-germanium-tin alloy layer; And / or, the first passivation layer and the second passivation layer each independently comprise silicon oxide and / or silicon nitride; And / or, the first electrode and the second electrode each independently include at least one of a Ni electrode, a Cr electrode, a Ti electrode, an Al electrode, and an Au electrode.
3. The method of fabricating a waveguide coupled photodetector of any of claims 1-2, wherein, Includes the following steps: (1) An optical waveguide layer is formed on the substrate layer, a first passivation layer with two electrode holes is formed on the optical waveguide layer, a first electrode is fabricated on the top of the first passivation layer and electrically connected to the optical waveguide layer through the electrode holes to obtain the substrate layer. (2) A first passivation layer is formed on top of the first passivation layer to seal the first electrode; (3) A hollow region is formed on the first passivation layer to expose the optical waveguide layer in the hollow region; and the exposed optical waveguide layer is processed to meet the requirements of epitaxial growth. (4) A buffer layer is formed on the surface of the exposed optical waveguide layer, and Ge is epitaxially grown on the buffer layer. 1-x Sn x Absorption layer; and in Ge 1- x Sn x A second passivation layer is formed on the absorption layer, and the second passivation layer covers the buffer layer and Ge. 1-x Sn x Absorption layer; (5) An electrode hole is made on the top of the first passivation layer to expose the first electrode, and the first electrode is made up to the top of the first passivation layer. (6) An electrode hole is formed on top of the second passivation layer, and a second electrode is formed so that it passes through the electrode hole and interacts with Ge. 1-x Sn x The absorption layer is electrically connected, where the value of X is 0 < x ≤ 0.
30.
4. The method for fabricating the waveguide-coupled photodetector according to claim 3, characterized in that, The method for forming the electrode hole includes: preparing the electrode hole on top of the first passivation layer or the second passivation layer by exposure and inductively coupled plasma etching. And / or, the method of forming the first electrode and the second electrode includes: evaporating metal in the first electrode hole or the second electrode hole by electron beam evaporation to obtain the first electrode or the second electrode; Preferably, the metal includes at least one selected from Ni, Cr, Ti, Al, and Au.
5. The method for fabricating the waveguide-coupled photodetector according to claim 3, characterized in that, In step (1), the optical waveguide layer is formed by means of exposure and inductively coupled plasma etching. And / or, the first passivation layer is formed by thermal oxidation or chemical vapor deposition.
6. The method for fabricating the waveguide-coupled photodetector according to claim 3, characterized in that, In step (2), the method for creating a hollow region on the first passivation layer includes exposure and inductively coupled plasma etching; And / or, in step (2), the method of processing the optical waveguide layer includes plasma treatment and / or wet chemical treatment.
7. The method of claim 3, wherein the waveguide-coupled photodetector is prepared by the steps of: providing a substrate; forming a waveguide on the substrate; forming a photodetector on the substrate; and coupling the photodetector to the waveguide. The method for forming the buffer layer includes chemical vapor deposition.
8. The method of claim 3, wherein the waveguide-coupled photodetector is prepared by the steps of: providing a substrate; forming a waveguide on the substrate; forming a photodetector on the substrate; and coupling the photodetector to the waveguide. The epitaxial growth of Ge 1-x Sn x Methods for creating an absorption layer include chemical vapor deposition, wherein the epitaxial growth of Ge 1-x Sn x The temperature of the absorption layer is ≤400℃.
9. The application of the waveguide-coupled photodetector according to any one of claims 1-2 or the waveguide-coupled photodetector obtained by the preparation method according to any one of claims 3-8 in near-infrared or mid-infrared optical detection.
10. Use according to claim 9, characterized in that, Application of the waveguide-coupled photodetector in optical detection in the 1.3µm to 4µm near-infrared or mid-infrared band.