Manufacturing method of Si photonics chip integrated with high-speed Ge photoelectric detector working for whole C and L wave bands

Abstract

A receiver for receiving an optical signal transmitted over a communication network, comprising: a silicon photonic substrate comprising a plurality of regions each having a different doping; an epitaxial germanium layer extending at least partially over at least two or more of the regions having different doping; and at least one of a tensile stressor feature and a compressive stressor feature in contact with the epitaxial germanium layer. The tensile stressor component and the compressive stressor component are respectively configured to mechanically strain the epitaxial germanium layer to modify an optical signal absorption property of the epitaxial germanium layer. The receiver includes a receiving circuit including at least one electrode component in electrical contact with the epitaxial germanium layer. The receive circuit is configured to generate an electrical output in response to an optical signal received by the epitaxial germanium layer from a network interface of the communication network.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 323,161, filed on March 24, 2022. The entire disclosures of the above-referenced applications are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to receivers for receiving optical signals transmitted over a communication network, and more particularly, to receivers including germanium-based photodetectors for detecting optical signals in the C-band and the L-band. Background Art

[0004] The background description provided herein is for the purpose of presenting the context of the present disclosure in general. The work of the presently designated inventors (to the extent that the work described in this background section) and some aspects of the description that would not have been considered prior art at the time of filing are neither explicitly nor implicitly admitted to be prior art to the present invention.

[0005] Broadband communication systems may include silicon photonic systems that meet different bandwidth, signal-to-noise ratio, and power requirements for short-distance, metropolitan, or long-distance data transmission. Silicon photonic devices may include active and passive components. Active components may include modulators and photodetectors. Passive components may include power dividers, polarization splitters-rotators, and input and output couplers. Active and passive devices may be connected to each other using waveguides. Summary of the invention

[0006] A receiver for receiving an optical signal transmitted through a communication network is disclosed, and the receiver includes: a silicon photonic substrate including a plurality of regions having different doping, an epitaxial germanium layer at least partially extending over at least two or more of the regions having different doping, and at least one of a tensile stressor component and a compressive stressor component in contact with the epitaxial germanium layer, the tensile stressor component and the compressive stressor component respectively configured to mechanically strain the epitaxial germanium layer to modify the optical signal absorption property of the epitaxial germanium layer. The receiver includes a receiving circuit including at least one electrode component in electrical contact with the epitaxial germanium layer, the receiving circuit being configured to generate an electrical output in response to an optical signal received by the epitaxial germanium layer from a network interface of the communication network.

[0007] In other features, the tensile stressor feature includes a tensile stressor film in contact with a lateral side of the epitaxial germanium layer. In other features, the tensile stressor film is a first tensile stressor film, the lateral side of the epitaxial germanium layer is the first lateral side, and the receiver includes a second tensile stressor film in contact with a second lateral side of the epitaxial germanium layer, the second lateral side being on a side of the epitaxial germanium layer opposite the first lateral side.

[0008] In other features, each of the first tensile stressor film and the second tensile stressor film comprises a silicon nitride tensile stressor film. In other features, the silicon nitride tensile stressor film is configured to mechanically strain the epitaxial germanium layer with a tensile stress of at least 400 MPa.

[0009] In other features, the compressive stressor component comprises a compressive stressor film in contact with a top surface of the epitaxial germanium layer. In other features, wherein the compressive stressor film comprises a silicon dioxide compressive stressor film.

[0010] In other features, at least one of the tensile stressor component and the compressive stressor component is configured to mechanically strain the epitaxial germanium layer with a tensile stress to modify a bandgap of the epitaxial germanium layer to detect optical signals having a wavelength in a range of at least 1530 nanometers to 1565 nanometers.

[0011] In other features, at least one of the tensile stressor component and the compressive stressor component is configured to mechanically strain the epitaxial germanium layer with a tensile stress to modify a bandgap of the epitaxial germanium layer to detect optical signals having a wavelength in a range of at least 1530 nanometers to 1625 nanometers.

[0012] In other features, the receiver includes a cladding layer at least partially covering the silicon photonic substrate and the epitaxial germanium layer, wherein the cladding layer includes an insulator material. In other features, the cladding layer is coextensive with the silicon photonic substrate.

[0013] In other features, the receiver includes at least one silicon nitride layer embedded in the cladding layer, the at least one silicon nitride layer defining at least a portion of a waveguide configured to transmit an optical signal received from a network interface of the communication network to the epitaxial germanium layer.

[0014] In other features, the at least one electrode component is a first electrode component in electrical contact with a first lateral side of the epitaxial germanium layer, and the receiver includes a second electrode component in electrical contact with a second lateral side of the epitaxial germanium layer, the second lateral side being on a side of the epitaxial germanium layer opposite to the first lateral side.

[0015] In other features, the first electrode member and the second electrode member are in electrical contact only with the first and second lateral sides of the epitaxial germanium layer to conduct current laterally through the epitaxial germanium layer to suppress dark current during periods when the epitaxial germanium layer does not detect an optical communication signal.

[0016] In other features, the epitaxial germanium layer is configured to operate as a high-speed photodiode for detecting optical communication signals transmitted through a network interconnect.

[0017] In other features, at least one of the tensile stressor component and the compressive stressor component is configured to mechanically strain the epitaxial germanium layer to modify a bandgap property of the epitaxial germanium layer to modify an optical signal absorption range of the epitaxial germanium layer.

[0018] A method of manufacturing a receiver for receiving optical signals transmitted through a communication network, and the method includes: doping a silicon photonic substrate to produce a plurality of regions having different dopings, respectively; depositing an epitaxial germanium layer, the epitaxial germanium layer at least partially extending over at least two or more of the regions having different dopings; and manufacturing a tensile stressor component in contact with a lateral side of the epitaxial germanium layer. The tensile stressor component is configured to mechanically strain the epitaxial germanium layer to modify the optical signal absorption properties of the epitaxial germanium layer. The method includes manufacturing at least one electrode component in electrical contact with the epitaxial germanium layer.

[0019] In other features, the tensile stressor component is a first tensile stressor component, the lateral side is a first lateral side, and the method further includes fabricating a second tensile stressor component in contact with a second lateral side of the epitaxial germanium layer, the first lateral side being on a side of the epitaxial germanium layer opposite the second lateral side. In other features, the method includes fabricating a compressive stressor component in contact with a top surface of the epitaxial germanium layer.

[0020] In other features, fabricating the tensile stressor component and fabricating the compressive stressor component includes specifying deposition parameters of the tensile stressor component and the compressive stressor component to mechanically strain the epitaxial germanium layer with a tensile stress to modify a band gap of the epitaxial germanium layer to detect an optical signal having a wavelength in a range of at least 1530 nanometers to 1565 nanometers.

[0021] In other features, fabricating the tensile stressor component and fabricating the compressive stressor component include specifying deposition parameters of the tensile stressor component and the compressive stressor component to mechanically strain the epitaxial germanium layer with tensile stress to modify a band gap of the epitaxial germanium layer to detect an optical signal having a wavelength in a range of at least 1530 nanometers to 1625 nanometers.

[0022] In other features, depositing the epitaxial germanium layer includes depositing the epitaxial germanium layer via an epitaxial process to a thickness greater than or equal to 300 nanometers and performing a chemical mechanical planarization process to remove a top portion of the epitaxial germanium layer.

[0023] In other features, fabricating the tensile stressor component includes performing a plasma enhanced chemical vapor deposition (PECVD) process to deposit a silicon nitride film having a tensile stress of at least 400 MPa; and specifying the tensile stress of the silicon nitride film according to parameters of the PECVD process. In other features, depositing the compressive stressor component includes performing a high density plasma chemical vapor deposition process to deposit a silicon dioxide film.

[0024] Other applicable aspects of the present disclosure will become clear from the detailed description, claims and drawings.The detailed description and specific examples are intended for illustrative purposes only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a side cross-sectional view of a receiver including a germanium-based photodetector for detecting optical signals in the C-band and the L-band.

[0026] Figure 2 is a side cross-sectional view of a receiver during an example fabrication process illustrating doping of a silicon photonics substrate and deposition of a cladding oxide layer.

[0027] Figure 3 is a side cross-sectional view of a receiver during an example manufacturing process, illustrating the removal of Figure 2 of a window in the encapsulating oxide layer.

[0028] Figure 4 is a side cross-sectional view of a receiver during an example manufacturing process, illustrating the Figure 3 Epitaxial deposition of germanium in a window.

[0029] Figure 5 is a side cross-sectional view of a receiver during an example manufacturing process, illustrating the Figure 4 Chemical mechanical planarization of the top portion of epitaxial germanium.

[0030] Figure 6 is a side cross-sectional view of a receiver during an example manufacturing process, illustrating the removal of Figure 5 Two windows on the lateral sides of the epitaxial germanium.

[0031] Figure 7 is a side cross-sectional view of a receiver during an example manufacturing process, illustrating the Figure 6 Deposition of lateral stressor films in two windows.

[0032] Figure 8 is a side cross-sectional view of a receiver during an example manufacturing process, illustrating Figure 7 Removal of excess portion of the lateral stressor film.

[0033] Fig. 9 is a side cross-sectional view of a receiver during an example manufacturing process, illustrating the Figure 8 Chemical mechanical planarization of the top surface of the epitaxial germanium layer.

[0034] Fig.10 is a side cross-sectional view of a receiver during an example manufacturing process, illustrating the Fig. 9 Deposition of a compressive stressor film above the top surface of the epitaxial germanium layer.

[0035] Fig.11 is a side cross-sectional view of a receiver during an example manufacturing process, illustrating the etching Fig.10 The excess compressive stress is the source of the film.

[0036] Fig.12 is a side cross-sectional view of a receiver during an example fabrication process, illustrating the etched waveguide window.

[0037] Fig.13 is a side cross-sectional view of a receiver during an example fabrication process, illustrating the deposition of a silicon nitride layer.

[0038] Fig.14 is a side cross-sectional view of a receiver during an example manufacturing process, illustrating the Fig.13 The waveguide is made from a silicon nitride layer.

[0039] Fig.15 is a side cross-sectional view of a receiver during an example manufacturing process, illustrating the deposition of a capping oxide layer.

[0040] Fig.16 is a side cross-sectional view of a receiver during an example manufacturing process, illustrating the fabrication of two electrode components.

[0041] Fig.17 is a flow chart of an example process for fabricating a germanium-based photodetector for detecting optical signals in the C-band and the L-band.

[0042] Fig.18 is a flow chart illustrating an example process for doping silicon photonic substrates.

[0043] Fig.19 is a flow chart illustrating an example process for depositing a germanium epitaxial layer.

[0044] Fig. 20 is a flow chart illustrating an example process for fabricating a tensile stressor feature in contact with an epitaxial germanium layer.

[0045] In the drawings, reference numerals may be used repeatedly to identify similar and / or identical elements. DETAILED DESCRIPTION

[0046] Silicon photonic circuits used for broadband telecommunications, data center connectivity, and biosensing applications include active and passive components. Waveguide assemblies are used to optically route signals to the various active and passive components. One type of waveguide assembly having a monolithic multilayer silicon photonic stack structure includes silicon (Si) strip waveguides and silicon nitride (SiN) strip waveguides, along with metal layers, germanium and oxide layers, and ion implants for electrical and optical signal transmission on the chip of the waveguide assembly.

[0047] Figure 1A side cross-sectional view of a receiver 100 for receiving an optical signal transmitted through a communication network is shown. The receiver 100 includes a germanium-based photodetector for detecting optical signals in the C-band and the L-band. The receiver 100 includes a silicon photonic substrate 102, which includes a plurality of regions having different dopings, respectively. A first region 104 is doped with a p-type doping (P+), a second region 106 is doped with an n-type doping (N+), a third region 108 is doped with a heavier p-type doping (P++) than the first region 104, and a fourth region 110 is doped with a heavier n-type doping (N++) than the second region 106. A non-doped region 112 is arranged between the first region 104 and the second region 106. The non-doped region 112 may be an undoped intrinsic region of the silicon photonic substrate 102.

[0048] The receiver 100 includes an epitaxial germanium layer 114 extending at least partially over the first region 104 and the second region 106. The epitaxial germanium layer 114 may include germanium deposited via an epitaxial deposition process, including a germanium crystal growth layer (e.g., having one or more defined orientations relative to a seed layer). The epitaxial germanium layer 114 extends over the undoped region 112. The receiver 100 also includes a first tensile stressor component 116 in contact with the epitaxial germanium layer 114, a second tensile stressor component 118 in contact with the epitaxial germanium layer 114, and a compressive stressor component 120 in contact with the epitaxial germanium layer 114.

[0049] The first tensile stressor feature 116 contacts a first lateral side of the epitaxial germanium layer 114, and the second tensile stressor feature 118 contacts a second lateral side of the epitaxial germanium layer 114. The first lateral side is on an opposite side of the epitaxial germanium layer 114 from the second lateral side. The compressive stressor feature 120 contacts a top surface of the epitaxial germanium layer 114.

[0050] although Figure 1 One compressive stressor component 120 and two tensile stressor components 116 and 118 are illustrated, but other example embodiments may include additional or fewer tensile stressor components and compressive stressor components (including zero tensile stressor components or compressive stressor components). In other example embodiments, the compressive stressor component 120 and the two tensile stressor components 116 and 118 may be located at other locations relative to the epitaxial germanium layer 114.

[0051] The receiving circuit includes a first electrode component 122 in electrical contact with the epitaxial germanium layer 114 and a second electrode component 124 in electrical contact with the epitaxial germanium layer 114. The first electrode component 122 electrically contacts the epitaxial germanium layer 114 through at least one of the first tensile stressor component 116, the first region 104, and the third region 108. The second electrode component 124 electrically contacts the epitaxial germanium layer 114 through at least one of the second tensile stressor component 118, the second region 106, and the fourth region 110.

[0052] The receiving circuit is configured to generate an electrical output in response to an optical signal received by the epitaxial germanium layer 114 from a network interface of the communication network. For example, an optical communication signal (such as light transmitted via a fiber optic cable) can be detected by the epitaxial germanium layer 114, and a value of the signal detection or signal non-detection can be transmitted by the first electrode component 122 and the second electrode component 124 to another portion of a receiving network interface of the communication network (which can include the receiver 100).

[0053] The first tensile stressor component 116, the second tensile stressor component 118, and the compressive stressor component 120 are configured to mechanically strain the epitaxial germanium layer 114 to modify the optical signal absorption properties of the epitaxial germanium layer 114. For example, in some embodiments, the first tensile stressor component 116 and the second tensile stressor component 118 are configured to mechanically strain the epitaxial germanium layer 114 with tensile stress. The compressive stressor component 120 is also configured to mechanically strain the epitaxial germanium layer 114 with tensile stress (e.g., due to the location of the compressive stressor component 120 on the top surface of the epitaxial germanium layer 114) to modify the band gap of the epitaxial germanium layer 114 to detect optical signals having wavelengths in the range of at least 1530 nanometers to 1565 nanometers. In this case, the epitaxial germanium layer 114 responds to optical signals having wavelengths in the entire C-band. When each of the first tensile stressor component 116 , the second tensile stressor component 118 , and the compressive stressor component 120 is in contact with the epitaxial germanium layer 114 , the compressive stressor component 120 may mechanically strain the epitaxial germanium layer with additional tensile stress in addition to the tensile stress due to the first tensile stressor component 116 and the second tensile stressor component 118 .

[0054] In some example embodiments, the first tensile stressor component 116 and the second tensile stressor component 118 are configured to mechanically strain the epitaxial germanium layer 114 with tensile stress, and the compressive stressor component 120 is configured to further mechanically strain the epitaxial germanium layer 114 with additional tensile stress (e.g., in addition to the tensile stress due to the first tensile stressor component 116 and the second tensile stressor component 118, based on the compressive stressor component 120 being located on the top surface of the epitaxial germanium layer 114) to modify the band gap of the epitaxial germanium layer 114 to detect optical signals having wavelengths in the range of at least 1530 nanometers to 1625 nanometers. In this case, the epitaxial germanium layer 114 responds to optical signals having wavelengths in the entire C-band and the entire L-band.

[0055] In various implementations, the amount of mechanical stress of the epitaxial germanium layer 114 may be tuned based on one or more deposition parameters that specify the first tensile stressor component 116, the second tensile stressor component 118, and the compressive stressor component 120. For example, the first tensile stressor component 116, the second tensile stressor component 118, and the compressive stressor component 120 may be deposited using a specified gas pressure, a specified gas composition, a specified temperature, etc. to induce a desired amount of mechanical stress in the epitaxial germanium layer 114, thereby increasing detection of the epitaxial germanium layer 114 for optical signals in a desired wavelength range.

[0056] The epitaxial germanium layer 114 is deposited layer by layer using an epitaxial deposition process and has a substantially zero stress crystal structure after deposition. When one or more of the first tensile stressor component 116, the second tensile stressor component 118, and the compressive stressor component 120 mechanically strain the epitaxial germanium layer 114, the electron mobility and the light absorption coefficient in the epitaxial germanium layer 114 are modified. For example, due to changes in the band diagram of the epitaxial germanium layer 114 based on the mechanical strain induced in the epitaxial germanium layer 114 by the first tensile stressor component 116, the second tensile stressor component 118, and the compressive stressor component 120, the photoresponsivity may be affected.

[0057] The optical absorption and detection range of the epitaxial germanium layer 114 can be modified to any desired range within the C-band and L-band wavelengths, such as the entire C-band and L-band (e.g., wavelengths of at least 1530 nm up to 1625 nm), wavelengths covering at least a portion of the entire C-band and L-band, wavelengths covering up to the entire C-band (e.g., wavelengths of at least 1530 nm up to 1565 nm), wavelengths covering a portion of the C-band, etc. In some example embodiments, the epitaxial germanium layer 114 can be modified to detect optical signals having wavelengths greater than or less than the example wavelength ranges listed above.

[0058] For example, an unstressed epitaxial germanium layer may have a light absorption range that only partially extends into the lower end of the C-band. Mechanically straining the epitaxial germanium layer 114 using at least one of the first tensile stressor component 116, the second tensile stressor component 118, and the compressive stressor component 120 may increase the light absorption range of the epitaxial germanium layer 114 to include more of the C-band wavelengths (including the entire C-band wavelength range), at least a portion of the L-band wavelengths, or up to the entire L-band wavelength range.

[0059] Increasing the signal detection wavelength range of epitaxial germanium layer 114 increases the available spectrum for optical fiber or other suitable communication medium to transmit communication signals to receiver 100. Increased spectrum utilization facilitates the use of more wavelengths in communication networks and allows optical fiber to transmit more data between devices in the communication network for higher bandwidth.

[0060] Mechanically straining the epitaxial germanium layer 114 using at least one of the first tensile stressor component 116, the second tensile stressor component 118, and the compressive stressor component 120 to modify the detection range of the epitaxial germanium layer 114 allows the use of germanium-based photodetectors and mature silicon photodetector manufacturing techniques. For example, the epitaxial germanium layer 114 can be configured to operate as a high-speed photodiode for detecting optical communication signals transmitted over a network interconnect. Mainstream manufacturing techniques can be used: the first tensile stressor component 116, the second tensile stressor component 118, and the compressive stressor component 120 are added during the normal silicon photonic substrate manufacturing process (without the need for specialized equipment or processes that add significant time to the manufacturing process).

[0061] The first tensile stressor component 116 and the second tensile stressor component 118 may be tensile stressor films. For example, the first tensile stressor component 116 and the second tensile stressor component 118 may include a silicon nitride tensile stressor film. The first tensile stressor component 116 and the second tensile stressor component 118 may be configured to mechanically strain the epitaxial germanium layer 114 with any suitable tensile stress, such as a tensile stress of at least 400 MPa.

[0062] The compressive stressor component 120 may include a compressive stressor film in contact with the top surface of the epitaxial germanium layer 114. For example, the compressive stressor film may include a silicon dioxide compressive stressor film. The compressive stressor component 120 may be configured to mechanically strain the epitaxial germanium layer 114 with any suitable tensile stress value (e.g., when the compressive stressor component 120 is located on the top surface of the epitaxial germanium layer 114).

[0063] The receiving layer 100 includes a cladding layer 126. The cladding layer 126 at least partially covers the silicon photonic substrate 102 and the epitaxial germanium layer 114. Figure 1As shown in , the cladding layer 126 is coextensive with the silicon photonic substrate 102. The cladding layer 126 includes an insulator material. One or more silicon nitride layers (or other suitable compound layers) can be embedded in the cladding layer 126. For example, at least one silicon nitride layer can be embedded in the cladding layer 126 to define at least a portion of a waveguide configured to transmit an optical signal received from a network interface of a communication network to the epitaxial germanium layer 114.

[0064] exist Figure 1 In the example embodiment illustrated in FIG. 1 , the first electrode component 122 and the second electrode component 124 are in electrical contact only with the first and second lateral sides of the epitaxial germanium layer 114 without any electrode component being positioned vertically above the epitaxial germanium layer 114. The arrangement of the first electrode component 122 and the second electrode component 124 at the lateral sides of the epitaxial germanium layer 114 causes current to be conducted laterally through the epitaxial germanium layer 114, rather than vertically upward out of the epitaxial germanium layer 114.

[0065] Conducting lateral current through the epitaxial germanium layer 114 suppresses dark current that occurs in the epitaxial germanium layer 114 during periods when the epitaxial germanium layer 114 does not detect an optical communication signal. For example, the lateral current conduction produces a smaller electric field in the epitaxial germanium layer 114 than a vertical field that penetrates the entire epitaxial germanium layer 114 to produce a larger current. Lower dark current contributes to lower noise and, therefore, a better signal-to-noise ratio (SNR) for the receiver 100.

[0066] Figure 2 A side cross-sectional view of the receiver 200 during an example silicon photonic substrate manufacturing process is shown, illustrating the doping of the silicon photonic substrate 202 and the deposition of the capping oxide layer 226. In some example embodiments, the silicon photonic substrate 202 may include a silicon-on-insulator (SOI) wafer having approximately a 220 nm silicon layer on top of a 3 μm insulator layer. The silicon photonic substrate 202 may be on top of a wafer backing layer 228.

[0067] One or more silicon waveguides may be defined by photolithography and etching. For example, a rib etch (such as a 60 nm bottom anti-reflective coating (BARC) etch, a 35 nm hard mask etch, and a 130 nm partial silicon etch) may be performed to define a plurality of silicon regions 230A, 230B, and 230C. Other suitable etch depths or etch processes may be used in other example embodiments. For example, a 90 nm slab etch may reduce a portion of the silicon to the surface of the silicon photonic substrate 202. A photoresist may be used during etching to control the etch depth at various regions.

[0068] In some example embodiments, a hard mask strip of sacrificial oxide may be deposited for implantation, such as using plasma enhanced chemical vapor deposition (PECVD) to deposit a 10 nm layer of silicon oxide. Different regions may be selectively doped to have different doping characteristics. For example, boron may be used as an implant for making P+ and P++ doped regions such as the first region 204, the third region 208, the fifth region 232, and the seventh region 236. Phosphorus may be used as an implant for making N+ and N++ doped regions such as the second region 206, the fourth region 210, the sixth region 234, and the eighth region 238. The receiver 200 may also include one or more non-doped regions, such as region 212.

[0069] In association with doping, one or more photolithography processes may be used, one or more wafer cleaning processes may be used, one or more photoresist strips may be used, etc. Any suitable dopant activation may be used, such as rapid thermal annealing (RTA) at a temperature of approximately 1030 degrees Celsius in approximately five seconds. In other example embodiments, other suitable dopant activation processes and parameters may be used. Any suitable process may be used to fabricate the capping oxide layer 226, such as depositing a 400 nm silicon oxide layer using PECVD. In some example embodiments, a pre-CMP reverse etch may be used with an additional silicon oxide fill deposition and chemical mechanical planarization (CMP) process.

[0070] Figure 3 A side cross-sectional view of receiver 200 is shown illustrating the removal of windows in cladding oxide layer 226. For example, windows 240 may be opened in cladding oxide layer 226 using an etching process. Figure 4 A side cross-sectional view of receiver 200 is shown illustrating epitaxial deposition of germanium in window 240. For example, selective epitaxy may be performed to deposit a germanium layer to form epitaxial germanium layer 214. Epitaxial germanium layer 214 may have any suitable deposition thickness, such as at least 300 nm.

[0071] Figure 5 2 is a side cross-sectional view of receiver 200 during an example manufacturing process, illustrating chemical mechanical planarization (CMP) for removing a top portion of epitaxial germanium layer 214. For example, a CMP process can be performed to remove a mushroom-shaped top portion of epitaxial germanium layer 214. After removing the top portion, epitaxial germanium layer 214 can have any suitable thickness, such as about 250 nm. A top surface of epitaxial germanium layer 214 can be substantially coplanar with a top surface of capping oxide layer 226.

[0072] Figure 6is a side cross-sectional view of receiver 200 illustrating two windows cleared out of the lateral sides of epitaxial germanium layer 214. For example, silicon oxide around the mesas of epitaxial germanium layer 214 may be removed from capping oxide layer 226 using etching.

[0073] Figure 7 2 is a side cross-sectional view of the receiver 200, illustrating the deposition of a tensile stressor film 242 in two windows created around the epitaxial germanium layer 214. For example, the tensile stressor film 242 may include a silicon nitride film deposited via PECVD. The film tensile stress value may be tuned to a desired stress value by selecting appropriate deposition parameters such as gas pressure, gas composition, temperature, etc. In some example embodiments, the tensile stressor film 242 may have a tensile stress value of at least 400 MPa or greater.

[0074] Figure 8 2 is a side cross-sectional view of the receiver 200 illustrating the removal of excess portions of the tensile stressor film 242. For example, etching may be performed to leave only a portion of the tensile stressor film 242 around the epitaxial germanium layer 214. Fig. 9 is a side cross-sectional view of receiver 200 illustrating chemical mechanical planarization used to expose the top surface of epitaxial germanium layer 214 .

[0075] Fig.10 is a side cross-sectional view of receiver 200 during an example fabrication process, illustrating deposition of compressive stressor film 244 over the top surface of epitaxial germanium layer 214. For example, compressive stressor film 244 may include a silicon oxide film deposited using PECVD with high density plasma (HDP). Fig.11 2 is a side cross-sectional view of the receiver 200, illustrating the etching of the excess portion of the compressive stressor film 244. Fig.11 As shown in , the compressive stressor film 244 is etched to cover only the top surface of the epitaxial germanium layer 214 and a portion of the tensile stressor film 242 on each side of the epitaxial germanium layer 214 .

[0076] Fig.12 is a side cross-sectional view of the receiver 200 during an example fabrication process, illustrating the etching of the waveguide window 246. The waveguide window 246 may be etched to any desired depth, such as leaving approximately 120 nm of silicon oxide on top of the silicon waveguide.

[0077] Fig.13 is a side cross-sectional view of receiver 200 illustrating the deposition of silicon nitride layer 248. For example, approximately 400 nm of silicon nitride may be deposited on top of capping oxide layer 226.

[0078] Fig.14is a side cross-sectional view of receiver 200 illustrating the fabrication of waveguides from silicon nitride layer 248. Silicon nitride layer 248 may be patterned and etched to form a plurality of waveguide regions, such as waveguide regions 250A, 250B, and 250C.

[0079] Fig.15 2 is a side cross-sectional view of receiver 200 during an example manufacturing process, illustrating the deposition of additional portions of capping oxide layer 226. Fig.15 As shown in , additional portions of the capping oxide layer 226 are deposited over the tops of the waveguide regions 250A, 250B, and 250C and over the compressive stressor film 244 and the tensile stressor film 242 .

[0080] Fig.16 2 is a side cross-sectional view of the receiver 200 during an example manufacturing process, illustrating the manufacturing of two electrode components. A first electrode component 252 is manufactured to extend through the capping oxide layer 226 and contact the tensile stressor film 242 at least on a first side of the epitaxial germanium layer 214, and a second electrode component 254 is manufactured to extend through the capping oxide layer 226 and contact the tensile stressor film 242 at least on a second lateral side of the epitaxial germanium layer 214.

[0081] Fig.17 1 is a flow chart of an example process for manufacturing a germanium-based photodetector for detecting optical signals in the C-band and the L-band. At 304, the process begins by doping a silicon substrate to produce a plurality of doped regions, which may each have different dopings (such as a P+ doped region, a P++ doped region, an N+ doped region, and an N++ doped region). Fig.18 An example process for doping a silicon photonic substrate is further described. At 308, the process includes depositing an epitaxial germanium layer extending at least partially over the plurality of doped regions. Fig.19 An example process for depositing an epitaxial germanium layer is further described.

[0082] At 312, the process includes fabricating a tensile stressor component in contact with a lateral side of the epitaxial germanium layer. The tensile stressor component is configured to mechanically strain the epitaxial germanium layer to modify the optical signal absorption properties of the epitaxial germanium layer. Fig. 20 An example process for fabricating a tensile stressor component is discussed further.At 316, the process includes fabricating at least one electrode component in electrical contact with the epitaxial germanium layer.

[0083] Fig.18 is a flow chart illustrating an example process for doping a silicon photonic substrate. At 404, the process includes performing photolithography and hard mask etching to define a silicon waveguide portion. At 408, the process includes performing a sacrificial oxide deposition to implant the doped region.

[0084] At 412, the process includes depositing a capping oxide layer. At 416, the process includes performing etch back, chemical mechanical planarization, and silicon oxide deposition to produce a silicon oxide layer having a substantially uniform top surface.

[0085] Fig.19 is a flow chart illustrating an example process for depositing a germanium epitaxial layer. At 504, the process includes opening a window for germanium deposition. Etching can be performed in the silicon oxide layer to open a window of a desired size to deposit germanium via an epitaxial process.

[0086] At 508, the process includes depositing a germanium layer via an epitaxial process. At 508, the process determines whether the desired depth or thickness of germanium has been deposited. For example, if the desired thickness of germanium is 300nm, the process will determine whether the height of the germanium deposited so far in the process has reached 300nm.

[0087] If the process determines at 512 that the desired depth of germanium has not been reached, the process proceeds to 516 to deposit an additional layer of germanium via an epitaxial process. In this manner, epitaxial deposition of germanium is performed layer by layer until the desired height of germanium is reached.

[0088] Once the desired germanium height is reached at 512, the process proceeds to 520 to perform chemical mechanical planarization on the epitaxial germanium layer. The chemical mechanical planarization process removes the mushroom-shaped top at the top portion of the epitaxial germanium layer.

[0089] Fig. 20 is a flow chart illustrating an example process for fabricating a tensile stressor component in contact with an epitaxial germanium layer. At 604, the process includes removing silicon oxide surrounding the epitaxial germanium layer. For example, the silicon oxide layer at the lateral side of the epitaxial germanium layer may be etched.

[0090] At 608, the process selects deposition parameters to produce a tensile stressor film. For example, deposition parameters such as gas pressure, gas composition, temperature, etc. may be adjusted to specify a desired tensile stress value for the tensile stressor film. At 612, the process includes depositing a tensile stressor film at a lateral side of the epitaxial germanium layer.

[0091] At 616, the process includes removing excess lateral stressor film via etching and performing chemical mechanical planarization. For example, the lateral stressor film can be etched away except for regions adjacent to the epitaxial germanium layer, and a chemical mechanical planarization process can be performed to expose a top surface of the epitaxial germanium layer.

[0092] At 620, the process includes selecting deposition parameters for producing the compressive stressor film. For example, the deposition parameters (such as gas pressure, gas composition, temperature, etc.) can be adjusted to specify the desired compressive stress value of the compressive stressor film. At 624, the process includes depositing the compressive stressor film over the top surface of the epitaxial germanium layer. At 628, the process includes etching the excess compressive stressor film so that only a portion of the compressive stressor film remains to cover the top surface of the epitaxial germanium layer and optionally cover at least a portion of the top surface of the tensile stressor film at the lateral side of the epitaxial germanium layer.

[0093] The foregoing description is merely illustrative in nature and is by no means intended to limit the present disclosure, its application or use. The broad teachings of the present disclosure can be implemented in various forms. Therefore, although the present disclosure includes specific examples, the true scope of the present disclosure should not be so limited, because other modifications will become apparent when studying the drawings, the specification and the following claims. It should be understood that one or more steps in the method can be performed in different orders (or simultaneously) without changing the principles of the present disclosure. In addition, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the present disclosure can be implemented and / or combined with the features of any other embodiment, even if the combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and the replacement of one or more embodiments with each other is still within the scope of the present disclosure.

[0094] When the relationship between the first element and the second element is described in the above disclosure, the relationship can be a direct relationship in which there are no other intervening elements between the first element and the second element, but it can also be an indirect relationship in which there are one or more intervening elements (spatially or functionally) between the first element and the second element. As used herein, at least one of the phrases A, B, and C should be interpreted as meaning the logic (AOR B OR C) using a non-exclusive logical OR, and should not be interpreted as meaning "at least one A, at least one B, and at least one C". In this application, the device elements described as having specific attributes or performing specific operations are specially configured to have those specific attributes and perform those specific operations. Although the terms first, second, third, etc. can be used in this article to describe various elements, components, and / or regions, these elements, components, and / or regions should not be limited by these terms unless otherwise indicated.

Claims

1. A receiver for receiving an optical signal transmitted through a communication network, the receiver include: A silicon photonic substrate, wherein the silicon photonic substrate comprises a plurality of regions respectively having different doping; an epitaxial germanium layer extending at least partially over at least two or more regions having different doping in the regions; at least one of a tensile stressor component and a compressive stressor component in contact with the epitaxial germanium layer, the tensile stressor component and the compressive stressor component respectively configured to mechanically strain the epitaxial germanium layer to modify an optical signal absorption property of the epitaxial germanium layer; as well as A receiving circuit includes at least one electrode component in electrical contact with the epitaxial germanium layer, the receiving circuit being configured to generate an electrical output in response to an optical signal received by the epitaxial germanium layer from a network interface of the communication network. 2 . The receiver of claim 1 , wherein the tensile stressor feature comprises a tensile stressor film in contact with a lateral side of the epitaxial germanium layer.

3. The receiver according to claim 2, in: The tensile stressor film is a first tensile stressor film; The lateral side of the epitaxial germanium layer is a first lateral side; and The receptor includes a second tensile stressor film in contact with a second lateral side of the epitaxial germanium layer, the second lateral side being on a side of the epitaxial germanium layer opposite the first lateral side. 4 . The receiver of claim 3 , wherein each of the first tensile stressor film and the second tensile stressor film comprises a silicon nitride tensile stressor film. 5 . The receiver of claim 4 , wherein the silicon nitride tensile stress film is configured to mechanically strain the epitaxial germanium layer with a tensile stress of at least 400 MPa. 6 . The receiver of claim 1 , wherein the compressive stressor component comprises a compressive stressor film in contact with a top surface of the epitaxial germanium layer.

7. The receiver of claim 6, wherein the compressive stressor film comprises a silicon dioxide compressive stress film.

8. The receiver of claim 1 , wherein at least one of the tensile stressor component and the compressive stressor component is configured to mechanically strain the epitaxial germanium layer with a tensile stress to modify a bandgap of the epitaxial germanium layer to detect an optical signal having a wavelength in a range of at least 1530 nanometers to 1565 nanometers.

9. The receiver of claim 8, wherein at least one of the tensile stressor component and the compressive stressor component is configured to mechanically strain the epitaxial germanium layer with a tensile stress to modify a bandgap of the epitaxial germanium layer to detect optical signals having a wavelength in a range of at least 1530 nanometers to 1625 nanometers.

10. The receiver of claim 1, further comprising a cladding layer at least partially covering the silicon photonics substrate and the epitaxial germanium layer, wherein the cladding layer comprises an insulator material.

11. The receiver of claim 10, wherein the cladding layer is coextensive with the silicon photonics substrate.

12. The receiver of claim 10, further comprising at least one silicon nitride layer embedded in the cladding layer, the at least one silicon nitride layer defining at least a portion of a waveguide configured to transmit an optical signal received from the network interface of the communication network to the epitaxial germanium layer.

13. The receiver according to claim 1, in: The at least one electrode feature is a first electrode feature in electrical contact with a first lateral side of the epitaxial germanium layer; and The receiver includes a second electrode feature in electrical contact with a second lateral side of the epitaxial germanium layer, the second lateral side being on a side of the epitaxial germanium layer opposite the first lateral side.

14. A receiver according to claim 13, wherein the first electrode component and the second electrode component are electrically contacted only with the first lateral side and the second lateral side of the epitaxial germanium layer to conduct current laterally through the epitaxial germanium layer to suppress dark current during a period when the epitaxial germanium layer does not detect an optical communication signal.

15. The receiver of claim 1, wherein the epitaxial germanium layer is configured to operate as a high-speed photodiode for detecting optical communication signals transmitted over a network interconnect.

16. The receiver of claim 1, wherein at least one of the tensile stressor component and the compressive stressor component is configured to mechanically strain the epitaxial germanium layer to modify a bandgap property of the epitaxial germanium layer to modify an optical signal absorption range of the epitaxial germanium layer.

17. A method of manufacturing a receiver for receiving an optical signal transmitted through a communication network, the method include: doping the silicon photonic substrate to generate a plurality of regions each having a different doping; depositing an epitaxial germanium layer extending at least partially over at least two or more regions having different doping in the regions; fabricating a tensile stressor feature in contact with a lateral side of the epitaxial germanium layer, the tensile stressor feature configured to mechanically strain the epitaxial germanium layer to modify an optical signal absorption property of the epitaxial germanium layer; as well as At least one electrode feature is fabricated in electrical contact with the epitaxial germanium layer.

18. The method of claim 17, wherein the tensile stressor feature is a first tensile stressor feature, the lateral side is a first lateral side, and the method further comprises fabricating a second tensile stressor feature in contact with a second lateral side of the epitaxial germanium layer, the first lateral side being on a side of the epitaxial germanium layer opposite the second lateral side.

19. The method of claim 17, further comprising fabricating a compressive stressor feature in contact with a top surface of the epitaxial germanium layer.

20. The method of claim 19, wherein manufacturing the tensile stressor component and manufacturing the compressive stressor component include: Deposition parameters of the tensile stressor component and the compressive stressor component are specified to mechanically strain the epitaxial germanium layer with a tensile stress to modify a band gap of the epitaxial germanium layer to detect optical signals having a wavelength in a range of at least 1530 nanometers to 1565 nanometers.

21. The method of claim 20, wherein manufacturing the tensile stressor component and manufacturing the compressive stressor component include: Deposition parameters of the tensile stressor component and the compressive stressor component are specified to mechanically strain the epitaxial germanium layer with a tensile stress to modify a band gap of the epitaxial germanium layer to detect optical signals having a wavelength in a range of at least 1530 nanometers to 1625 nanometers.

22. The method of claim 17, wherein the epitaxial germanium layer is deposited include: Depositing the epitaxial germanium layer to a thickness greater than or equal to 300 nanometers via an epitaxial process; as well as A chemical mechanical planarization process is performed to remove a top portion of the epitaxial germanium layer.

23. The method according to claim 17, in: Fabricating the tensile stressor component includes performing a plasma enhanced chemical vapor deposition (PECVD) process to deposit a silicon nitride film having a tensile stress of at least 400 MPa; as well as The tensile stress of the silicon nitride film is specified according to the parameters of the PECVD process.

24. The method of claim 19, wherein depositing the compressive stressor component comprises performing a high density plasma chemical vapor deposition process to deposit a silicon dioxide film.

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