Optical structures, semiconductor structures and methods for forming optical structures

Abstract

An optical structure, a semiconductor structure, and a method for forming the optical structure are disclosed. The optical structure is provided by the following steps: forming a silicon grating structure on a dielectric material layer; depositing at least one dielectric material layer on the silicon grating structure; and depositing a layer stack including a first dielectric etch stop layer and a second dielectric etch stop layer on the at least one dielectric material layer. The first and second dielectric etch stop layers include a dielectric material selected from silicon nitride and silicon oxynitride, and the second dielectric etch stop layer includes a dielectric material different from that of the first dielectric etch stop layer. A passivation dielectric layer may be formed on the layer stack, and a patterned etch mask layer may be formed on the passivation dielectric layer. An opening may be formed through an unmasked portion of the passivation dielectric layer by performing an anisotropic etching process, which etches a dielectric material selective to silicon nitride or silicon oxynitride by using the patterned etch mask layer as a mask structure. At least one etch mask layer minimizes over-etching.

Description

Technical Field

[0001] This disclosure relates to an optical structure, a semiconductor structure, and a method for forming an optical structure. Background Technology

[0002] Silicon photonic coupling is used to provide on-chip optical interconnects between optical fibers and photonic devices, such as light sources or photosensors. Silicon photonic coupling provides multi-channel, high-performance computing and high-capacity data storage servers, and consumes less energy per bit compared to known memory devices that use current flow for signal transmission. Summary of the Invention

[0003] This disclosure provides an optical structure including a silicon grating structure, at least one dielectric material layer, a layer stack, a passivation dielectric layer, and an optical fiber. The silicon grating structure is positioned on an embedded insulating layer. At least one dielectric material layer covers and contacts the silicon grating structure. The layer stack covers at least one dielectric material layer and includes a first dielectric etch stop layer and a second dielectric etch stop layer, each comprising a dielectric material selected from silicon nitride and silicon oxynitride, and the second dielectric etch stop layer comprising a dielectric material different from the first dielectric etch stop layer. The passivation dielectric layer comprises a dielectric material and covers the layer stack, and includes an opening covering an end portion of the silicon grating structure, wherein the opening does not contain the dielectric material of the passivation dielectric layer, or the opening comprises the dielectric material of a passivation dielectric layer of a thickness less than 10% of the thickness of the passivation dielectric layer outside the opening. The optical fiber covers the opening in the passivation dielectric layer and includes an end surface for receiving or emitting light directed to the opening in the passivation dielectric layer. The stacked layers are separated from the opening by a portion of the passivation dielectric layer and are not exposed by the opening, or one of the first dielectric etch stop layer and the second dielectric etch stop layer is exposed through the opening and the other of the first dielectric etch stop layer and the second dielectric etch stop layer is not exposed by the opening.

[0004] This disclosure provides a semiconductor structure comprising a semiconductor die and an optical fiber. The semiconductor die, from bottom to top, includes a silicon substrate, a buried insulating layer, a silicon grating structure, at least one dielectric material layer, a stack of layers including a first dielectric etch stop layer and a second dielectric etch stop layer, and a passivation dielectric layer. The passivation dielectric layer includes a dielectric material and includes an opening at the end portion of the silicon grating structure. The optical fiber is covered by the opening in the passivation dielectric layer and optically coupled to the silicon grating structure through the opening in the passivation dielectric layer, and attached to the semiconductor die via an optical molding structure. The at least one dielectric material layer includes at least one dielectric material selected from silicon nitride and silicon oxynitride. The first dielectric etch stop layer and the second dielectric etch stop layer each include a dielectric material selected from silicon nitride and silicon oxynitride; the second dielectric etch stop layer includes a dielectric material different from that of the first dielectric etch stop layer; both the first dielectric etch stop layer and the second dielectric etch stop layer are disposed below the bottom surface of the opening; and one of the first dielectric etch stop layer and the second dielectric etch stop layer is perpendicularly spaced from the opening and is not exposed through the opening.

[0005] This disclosure provides a method for forming an optical structure, comprising the following operations: forming a silicon grating structure on an embedded insulating layer; depositing at least one dielectric material layer on the silicon grating structure; depositing a layer stack including a first dielectric etch stop layer and a second dielectric etch stop layer on the at least one dielectric material layer, wherein the first and second dielectric etch stop layers each include at least one dielectric material selected from silicon nitride and silicon oxynitride, and the second dielectric etch stop layer includes a dielectric material different from the first dielectric etch stop layer; forming a passivation dielectric layer including a dielectric material on the layer stack; forming a patterned etch mask layer on the passivation dielectric layer, wherein the patterned etch mask layer includes an opening in a region covering the end portion of the silicon grating structure; forming the opening through the unmasked portion of the passivation dielectric layer by performing an anisotropic etching process, the anisotropic etching process etching a dielectric material selective to silicon nitride or silicon oxynitride by using the patterned etch mask layer as a mask structure. The stacked layers are separated from the opening by a portion of the passivation dielectric layer and are not exposed by the opening, or one of the first dielectric etch stop layer and the second dielectric etch stop layer is exposed through the opening and the other of the first dielectric etch stop layer and the second dielectric etch stop layer is not exposed by the opening. Attached Figure Description

[0006] When read in conjunction with the accompanying drawings, the following detailed description is the best way to understand the various aspects of this disclosure. It should be noted that, according to industry standard practice, the various features are not drawn to scale. In fact, for the purpose of clarity, the dimensions of the various features may be arbitrarily increased or decreased.

[0007] Figure 1This is a perspective view of an exemplary optical structure according to an embodiment of this disclosure;

[0008] Figure 2A This is a vertical cross-sectional view of a first configuration of an exemplary optical structure according to an embodiment of this disclosure after the formation of a passivation dielectric layer;

[0009] Figure 2B This is a vertical cross-sectional view of a first configuration of an exemplary optical structure according to an embodiment of this disclosure after a patterned etched mask layer has been formed;

[0010] Figure 2C This is a vertical cross-sectional view of a first configuration of an exemplary optical structure according to an embodiment of this disclosure after forming an opening through a passivation dielectric layer;

[0011] Figure 2D This is a vertical cross-sectional view of a first configuration of an exemplary optical structure according to an embodiment of this disclosure after the optical fiber has been attached.

[0012] Figure 2E This is a vertical cross-sectional view of an alternative embodiment of a first configuration of an exemplary optical structure according to an embodiment of this disclosure, after the optical fiber has been attached.

[0013] Figure 3A This is a vertical cross-sectional view of a second configuration of an exemplary optical structure according to an embodiment of this disclosure;

[0014] Figure 3B This is a vertical cross-sectional view of an alternative embodiment of a second configuration of an exemplary optical structure according to an embodiment of this disclosure;

[0015] Figure 4A This is a vertical cross-sectional view of a fourth configuration of an exemplary optical structure according to an embodiment of this disclosure;

[0016] Figure 4B This is a vertical cross-sectional view of an alternative embodiment of a fourth configuration of an exemplary optical structure according to an embodiment of this disclosure;

[0017] Figure 4C This is a plan view of a fourth configuration of an exemplary optical structure according to an embodiment of this disclosure;

[0018] Figure 5A This is a vertical cross-sectional view of a fourth configuration of an exemplary optical structure according to an embodiment of this disclosure;

[0019] Figure 5B This is a vertical cross-sectional view of an alternative embodiment of a fourth configuration of an exemplary optical structure according to an embodiment of this disclosure;

[0020] Figure 5CThis is a plan view of a fourth configuration of an exemplary optical structure according to an embodiment of this disclosure;

[0021] Figure 6A This is a vertical cross-sectional view of a fifth configuration of an exemplary optical structure according to an embodiment of this disclosure after the formation of a first patterned dielectric etch stop layer;

[0022] Figure 6B This is a vertical cross-sectional view of a fifth configuration of an exemplary optical structure according to an embodiment of this disclosure after the formation of a second patterned dielectric etch stop layer;

[0023] Figure 6C This is a vertical cross-sectional view of a fifth configuration of an exemplary optical structure according to an embodiment of this disclosure after forming an opening through a passivation dielectric layer;

[0024] Figure 6D This is a vertical cross-sectional view of an alternative embodiment of a fifth configuration of an exemplary optical structure according to an embodiment of this disclosure, after the optical fiber has been attached.

[0025] Figure 6E This is a plan view of a fifth configuration of an exemplary optical structure according to an embodiment of this disclosure;

[0026] Figure 7A This is a vertical cross-sectional view of a sixth configuration of an exemplary optical structure according to an embodiment of this disclosure, after an opening is formed through the passivation dielectric layer;

[0027] Figure 7B This is a vertical cross-sectional view of an alternative embodiment of a sixth configuration of an exemplary optical structure according to an embodiment of this disclosure, after the optical fiber has been attached.

[0028] Figure 7C This is a plan view of a sixth configuration of an exemplary optical structure according to an embodiment of this disclosure;

[0029] Figure 8 This is a vertical cross-sectional view of an exemplary semiconductor die of the present disclosure after it has been attached to an optical fiber, according to an embodiment of the present disclosure.

[0030] Figure 9 This is a flowchart illustrating the steps of forming a silicon photonic device according to an embodiment of the present disclosure.

[0031] [Symbol Explanation]

[0032] 10: Silicon substrate

[0033] 20: Embedded insulation layer

[0034] 30: Silicon grating structure

[0035] 32: Silicon wiring structure

[0036] 50: Silicon photonics device

[0037] 60: Dielectric material layer

[0038] 62: First silicon oxide layer

[0039] 63: Contact Etching Stop Pad

[0040] 64: Second silicon oxide layer

[0041] 66: Dielectric Etching Stop Layer

[0042] 66A: First dielectric etch stop layer

[0043] 66B: Second dielectric etch stop layer

[0044] 69: Opening

[0045] 69S: Sidewall

[0046] 70: Passivation dielectric layer

[0047] 70R: Dielectric material part

[0048] 77: Patterned Etched Mask Layer

[0049] 80: Optical Fiber

[0050] 82: Light

[0051] 84: Optical molding structure

[0052] 100: Semiconductor die

[0053] 150: Welding ball

[0054] 200: Substrate

[0055] 250: Steps

[0056] 910: Steps

[0057] 920: Steps

[0058] 930: Steps

[0059] 940: Steps

[0060] 950: Steps

[0061] 960: Steps Detailed Implementation

[0062] The following disclosure provides numerous different embodiments or instances for implementing various features of the provided subject matter. Specific examples of components and configurations are described below to simplify this disclosure. Of course, these are merely examples and are not intended to be limiting. For example, in the following description, manufacturing a first feature on or above a second feature may include embodiments in which the first and second features are manufactured in direct contact, and may also include embodiments in which an additional feature may be manufactured between the first and second features such that the first and second features are not in direct contact. Additionally, element symbols and / or letters may be repeated in various instances of this disclosure. This repetition is for simplicity and clarity and does not in itself indicate a relationship between the various embodiments and / or configurations discussed.

[0063] Furthermore, spatial relative terms such as “below,” “under,” “down,” “above,” and “up” may be used herein for descriptive purposes to describe the relationship between one element or feature and another element(s), as illustrated in the figures. In addition to the orientations depicted in the figures, the spatial relative terms are also intended to cover different orientations of the device in use or operation. The device may be oriented in other ways (rotated 90 degrees or otherwise), and the spatial relative descriptive terms used herein may be interpreted accordingly. Unless otherwise explicitly stated, it is assumed that each element with the same element symbol has the same material composition and a thickness within the same thickness range.

[0064] Embodiments of this disclosure relate to a silicon photonic device including an optical coupling structure for coupling with an optical fiber. Specifically, embodiments of this disclosure relate to a silicon photonic device and a method of forming the same, the silicon photonic device including at least one dielectric etch stop layer for controlling the vertical cross-sectional profile of an opening through a passivated dielectric layer above an end portion of a silicon grating structure, various forms of which are now described in detail.

[0065] Various passive and active silicon photonic devices are known in this field. These silicon photonic devices can generate optical signals (as in the case of a light source), detect optical signals (as in the case of a photodetector), or split or amplify optical signals.

[0066] Reference Figure 1The figure illustrates an exemplary optical structure according to an embodiment of this disclosure using a perspective view. The exemplary optical structure can be formed using a silicon-on-insulator (SOI) substrate, comprising a silicon substrate 10, a buried insulating layer 20 including silicon oxide, and a top semiconductor layer. The silicon substrate 10 may have a thickness ranging from 500 micrometers to 1 mm. The thickness of the buried insulating layer 20 can be determined to minimize optical reflections at the interface with the silicon substrate 10. For example, the thickness of the buried insulating layer 20 may range from 100 nm to 400 nm, and may be about 200 nm, although smaller and larger thicknesses are also possible. The buried insulating layer 20 may include silicon oxide, such as thermal silicon oxide, i.e., stoichiometric silicon oxide having the composition SiO2 and formed from a thermal oxide of silicon.

[0067] A patternable top semiconductor layer can be used to provide a silicon grating structure 30. The silicon grating structure 30 includes a one-dimensional periodic array of silicon wiring structures 32 of uniform height coupled to the top surface of a silicon substrate. One end of the silicon substrate (referred to herein as the far end) can be tapered to provide a variable width that decreases with lateral distance from the one-dimensional periodic array of silicon wiring structures 32. The vertical distance between the top surface of the silicon wiring structures 32 and the bottom surface of the silicon substrate can range from 10 nm to 300 nm and can be selected depending on the wavelength of the light used for optical communication. In one embodiment, the vertical distance can be approximately 220 nm. The pitch of the silicon wiring structures 32 along a direction perpendicular to the lengthwise direction of the silicon wiring structures 32, i.e., along the direction of the pitch of the silicon wiring structures 32 (the same as the lengthwise direction of the silicon grating structure 30), can be the same as the wavelength of the light used for optical communication within the silicon medium of the silicon grating structure 30 along the periodic direction of the silicon grating structure 30. Because the relative permittivity of silicon (i.e., the dielectric constant of silicon) is approximately 11.7, the pitch of the silicon wiring structure 32 along the length direction of the silicon grating structure 30 can be equal to the wavelength of the light used for optical communication divided by 11.7. For example, the pitch of the silicon wiring structure 32 along the periodic direction of the silicon grating structure 30 can be in the range of 80 nm to 200 nm, although smaller and larger pitches can also be used. The silicon photonic device 50 can be coupled to the distal end of the silicon grating structure 30. For example, an optical switch, a light source, or a photodetector can be coupled to the distal end of the silicon grating structure 30.

[0068] The silicon grating structure 30 can be formed by patterning the top semiconductor layer using two patterning processes. A first patterning process can be used to define the boundaries of the silicon grating structure 30. A second patterning process can be used to recess the region of the silicon grating structure 30 located outside the region of the silicon wiring structure 32. Each silicon wiring structure 32 may have the same vertical cross-sectional shape in a vertical plane extending along the length direction of the silicon grating structure 30. In one embodiment, each silicon wiring structure 32 may have the same rectangular cross-sectional shape in a vertical plane extending along the length direction of the silicon grating structure 30.

[0069] A silicon grating structure 30 can be used to provide optical coupling between the optical fiber 80 and the silicon photonic device 50. The silicon grating structure 30 can be provided on the embedded insulating layer 20. Specifically, it is a combination of the silicon grating structure 30, at least one dielectric material layer ({62,63,64}; collectively referred to as at least one dielectric material layer 60), and a passivation dielectric layer 70, wherein the at least one dielectric material layer overlies the silicon grating structure 30 and provides a contrast in refractive index at the interface with the silicon grating structure 30, and the dielectric layer 70 overlies the at least one dielectric material layer 60 and includes an opening 69 through the passivation dielectric layer 70.

[0070] Typically, at least one dielectric material layer 60 may be formed on a silicon grating structure 30 having a flat top surface (i.e., a top surface contained within a horizontal plane). In one embodiment, the at least one dielectric material layer 60 may include, from bottom to top, a first silicon oxide layer 62 contacting the silicon grating structure 30, a contact etch stop liner (CESL) 63 covering the first silicon oxide layer 62, and a second silicon oxide layer 64 contacting the contact etch stop liner 63.

[0071] The first silicon oxide layer 62 can be formed by depositing and planarizing silicon oxide material. In one embodiment, the first silicon oxide layer 62 can be deposited by chemical vapor deposition, and the top surface of the first silicon oxide layer 62 can be planarized by a chemical mechanical planarization process. Alternatively, the first silicon oxide layer 62 can be formed by a self-planarization deposition process (such as spin coating). The first silicon oxide layer 62 can have a thickness in the range of 5 micrometers to 10 micrometers (measured from the top surface of the silicon grating structure 30 to the interface with the contact etch stop pad 63), although smaller and larger thicknesses can also be used.

[0072] The contact etch stop pad 63 includes a dielectric material that can be used as an etch stop material during the formation of contact via structures (not explicitly illustrated) for various components of the contact silicon photonic device. The contact etch stop pad 63 may include dielectric materials such as dielectric metal oxides (e.g., aluminum oxide, titanium oxide, tantalum oxide, yttrium oxide, etc.), silicon nitride, silicon carbide, and / or silicon carbide. The thickness of the contact etch stop pad 63 can be selected to minimize optical interference with light transmitted between the silicon grating structure 30 and the optical fiber 80. For example, the thickness of the contact etch stop pad 63 can be in the range of 20 nm to 100 nm, although smaller and larger thicknesses can also be used.

[0073] The second silicon oxide layer 64 can be formed by depositing silicon oxide material. For example, the second silicon oxide layer 64 can be deposited using chemical vapor deposition. The second silicon oxide layer 64 can have a thickness in the range of 150 nm to 500 nm, although smaller and larger thicknesses can also be used.

[0074] According to embodiments of this disclosure, at least one dielectric etch stop layer 66 may be deposited over at least one dielectric material layer 60. The at least one dielectric etch stop layer 66 comprises a dielectric material different from the dielectric material of a subsequently deposited dielectric passivation layer. The at least one dielectric etch stop layer 66 comprises at least one dielectric material selected from silicon nitride and silicon oxynitride. The at least one dielectric etch stop layer 66 may consist of a single dielectric etch stop layer or may comprise multiple dielectric etch stop layers, which may be patterned or unpatterned. The total thickness of the at least one dielectric etch stop layer 66 may range from 20 nm to 300 nm, although smaller and larger thicknesses may also be used. Various configurations of the at least one dielectric etch stop layer 66 are described in detail in subsequent sections. Typically, the at least one dielectric etch stop layer 66 is used to prevent localized over-etching of the underlying portion of the at least one dielectric material layer 60. Specifically, the at least one dielectric material layer 60 may be used to prevent over-etching of the underlying portion of the at least one dielectric material layer 60 at the periphery of an opening that will subsequently be formed through the passivation dielectric layer.

[0075] Subsequently, a passivation dielectric layer 70 comprising a dielectric material may be deposited over at least one dielectric etch stop layer 66. The passivation dielectric layer 70 may comprise one or more of silicon carbide, silicon nitride, undoped silicate glass, doped silicate glass, silicon oxynitride, organosilicon glass, or low-k dielectric materials (such as porous organosilicon glass). In one embodiment, the thickness of the passivation dielectric layer 70 may be selected to provide sufficient shielding against ambient light to prevent optical noise from entering the silicon grating structure 30 or the silicon photonic device 50. In the illustrated example, the passivation dielectric layer 70 may have a thickness ranging from 3 micrometers to 30 micrometers, such as from 4 micrometers to 10 micrometers, although smaller and larger thicknesses may also be utilized. In one embodiment, the passivation dielectric layer 70 may be formed using a chemical vapor deposition process.

[0076] A patterned etch mask layer (such as a patterned photoresist layer (not shown)) may be formed over the passivation dielectric layer 70. The patterned etch mask layer may include an opening in the region of the end portion of the overlying silicon grating structure 30. The opening 69 may be formed through the unmasked portion of the passivation dielectric layer 70 by performing an anisotropic etching process. The anisotropic etching process may use the patterned etch mask layer as a mask structure to etch the dielectric material of the passivation dielectric layer 70, which is selective to the dielectric material in at least one dielectric etch stop layer 66. In one embodiment, the passivation dielectric layer 70 may have an initial thickness prior to the anisotropic etching process. The duration of the anisotropic etching process may be selected such that the opening 69 may be free of the dielectric material of the passivation dielectric layer 70, or include the dielectric material of the passivation dielectric layer 70, wherein the thickness is less than 10% of the initial thickness of the passivation dielectric layer 70 (e.g., less than 5%, and / or less than 2%, and / or less than 1%). While uniform thickness is desirable for any remaining portion of the dielectric material below the opening 69 in the passivation dielectric layer 70, a non-uniform thickness distribution of the remaining portion of the dielectric material in the passivation dielectric layer 70 below the opening 69 is common. Typically, any remaining portion of the dielectric material in the passivation dielectric layer 70 below the opening 69 may have a greater thickness in the central region of the opening 69 and a smaller thickness or be completely etched in the peripheral region of the opening 69. Additionally, at least a portion of a dielectric etch stop layer 66 may be incidentally etched in the peripheral portion of the opening 69. The lateral dimensions of the opening 69 may range from 2 micrometers to 10 micrometers, such as from 3 micrometers to 6 micrometers, although larger or smaller lateral dimensions may be utilized. For example, the opening 69 may have a rectangular horizontal shape, with each side having a length ranging from 2 micrometers to 10 micrometers, such as from 3 micrometers to 6 micrometers, although smaller and larger lengths may be utilized.

[0077] According to embodiments of this disclosure, silicon oxide or silicon nitride is used to increase the etch resistance of at least one dielectric etch stop layer 66 during anisotropic etch processes. According to some embodiments of this disclosure, at least one dielectric etch stop layer 66 may be formed at the periphery of the opening 69 to increase etch resistance, while a smaller thickness of the dielectric etch stop layer 66 is provided in the central region of the opening 69 to minimize optical effects attributable to the dielectric etch stop layer 66. In one embodiment, the passivation dielectric layer 70 may extend continuously within the opening 69 and may have a thickness in the range of 1 nm to 200 nm, and a thickness in the range of 3 μm to 30 μm outside the opening in the passivation dielectric layer 70. Alternatively, a separate residual portion of dielectric material (not explicitly illustrated) may be formed at the central portion of the opening 69 that is not physically connected to the passivation dielectric layer 70. The discrete portions of the dielectric material of the passivation dielectric layer 70 may have a variable thickness, which may be in the range of 1 nm to 200 nm. The discrete portions of the dielectric material in the opening 69 may have the same material composition as the flat portions of the passivated dielectric layer 70, which has a uniform thickness (the initial thickness).

[0078] Subsequently, an optical fiber 80 may be disposed above the opening 69 in the passivation dielectric layer 70. The optical fiber 80 includes an end surface for receiving or emitting light 82 guided to the opening 69 in the passivation dielectric layer 70.

[0079] generally, Figure 1 The exemplary optical structure illustrated in the figure may include: a silicon grating structure 30 positioned on a buried insulating layer 20; at least one dielectric material layer 60 covering and contacting the silicon grating structure 30; at least one dielectric etch stop layer 66 covering at least one dielectric material layer 60 and including at least one dielectric material selected from silicon nitride and silicon oxynitride; and a passivation dielectric layer 70 including a dielectric material and It is covered with at least one dielectric etch stop layer 66 and includes an opening 69 at the end portion of the covered silicon grating structure 30, wherein the opening 69 is free of the dielectric material of the passivation dielectric layer 70, or includes the dielectric material of the passivation dielectric layer 70, wherein the thickness is less than 10% of the thickness of the passivation dielectric layer 70 outside the opening 69; and an optical fiber 80 covered with the opening 69 in the passivation dielectric layer 70 and including an end surface for receiving or emitting light 82 directed to the opening 69 in the passivation dielectric layer 70.

[0080] At least one dielectric etch stop layer 66 can be provided in various configurations, now referencing Figures 2A to 7C describe.

[0081] Figure 2A This is a vertical cross-sectional view of a first configuration of an exemplary optical structure according to an embodiment of this disclosure after the formation of a passivation dielectric layer 70. In the first configuration, at least one dielectric etch stop layer 66 comprises a single dielectric etch stop layer 66 having a homogeneous material composition and contacting the flat top surface of at least one dielectric material layer 60 and the bottom surface of the passivation dielectric layer 70 over the entire region of the silicon grating structure 30. In other words, the single dielectric etch stop layer 66 extends continuously over the entire region of the silicon grating structure 30. In one embodiment, the single dielectric etch stop layer 66 may be formed as a blanket dielectric material layer, i.e., an unpatterned dielectric material layer. The single dielectric etch stop layer 66 may be deposited by chemical vapor deposition. In one embodiment, the single dielectric etch stop layer 66 may consist substantially of silicon nitride. In another embodiment, the single dielectric etch stop layer 66 may consist substantially of silicon oxynitride comprising nitrogen atoms at an atomic concentration greater than 10% (e.g., between 15% and 50%). The thickness of a single dielectric etch stop layer 66 can be in the range of 20 nm to 150 nm, such as between 30 nm and 70 nm, although smaller and larger thicknesses can also be used.

[0082] Figure 2B This is a vertical cross-sectional view of a first configuration of an exemplary optical structure according to an embodiment of this disclosure after the formation of a patterned etch mask layer 77. In one embodiment, the patterned etch mask layer 77 may be a patterned photoresist layer, which is formed by etching exposure and development by coating a blanket photoresist material layer over a passivation dielectric layer 70 and by patterning the blanket photoresist material layer. Openings in the patterned etch mask layer 77 may be formed over the distal portion of the silicon grating structure 30, including the silicon wiring structure 32. At least one sidewall of the opening in the patterned etch mask layer 77 may extend over the silicon grating structure 30.

[0083] Figure 2CThis is a vertical cross-sectional view of a first configuration of an exemplary optical structure according to an embodiment of this disclosure after forming an opening 69 through the passivation dielectric layer 70. An anisotropic etching process is performed to etch the unmasked portion of the passivation dielectric layer 70. The anisotropic etching process may include an etching chemical that etches the dielectric material of the passivation dielectric layer 70, which is selectively applied to silicon nitride or silicon oxynitride of a single dielectric etch stop layer 66. In one embodiment, the anisotropic etching process may utilize a fluorinated plasma generated by at least one hydrofluorocarbon gas and / or at least one fluorocarbon gas. In one embodiment, the duration of the anisotropic etching process may be selected such that the opening 69 is either free of the dielectric material of the passivation dielectric layer 70 or includes the dielectric material of the passivation dielectric layer 70, wherein the thickness is less than 10% (e.g., less than 5%, and / or less than 2%, and / or less than 1%) of the passivation dielectric layer thickness (i.e., the thickness of the passivation dielectric layer 70 below the patterned etch mask layer 77).

[0084] Figure 2D This is a vertical cross-sectional view of a first configuration of an exemplary optical structure according to an embodiment of this disclosure after the removal of a patterned etched mask layer 77 and the attachment of optical fiber 80. The patterned etched mask layer 77 can be removed, for example, by ashing. The optical fiber 80 can be positioned such that light 82 is induced to optically couple between the silicon grating structure 30 and the optical fiber 80. The optical fiber 80 can be attached to a target location using an optical molding compound (not shown), which can fill openings 69 in the passivated dielectric layer 70. Figure 2D The illustration shows an embodiment in which the passivation dielectric layer 70 extends continuously within an opening 69 and has a thickness within the opening 69 ranging from 1 nm to 200 nm. The thickness of the portion of the passivation dielectric layer 70 within the opening 69 may be uniform or non-uniform.

[0085] Figure 2E This is a vertical cross-sectional view of an alternative embodiment of a first configuration of an exemplary optical structure according to an embodiment of this disclosure, after the patterned etch mask layer 77 and the attached optical fiber 80 have been removed. In this embodiment, a dielectric material portion 70R comprising the dielectric material of the passivation dielectric layer 70 is positioned on the top surface of a single dielectric etch stop layer 66 at the central region of the opening 69, and is laterally spaced from and does not contact the sidewalls of the opening in the passivation dielectric layer 70. Therefore, discrete portions of dielectric material that are not physically connected to the passivation dielectric layer 70 can be formed at the central portion of the opening 69. The discrete portions of dielectric material may have a variable thickness, ranging from 1 nm to 200 nm. The dielectric material portion 70R in the opening 69 may have the same material composition as the flat portion of the passivation dielectric layer 70 having a uniform thickness (the initial thickness).

[0086] Figure 3AThis is a vertical cross-sectional view of a second configuration of an exemplary optical structure according to an embodiment of this disclosure. In the second configuration, at least one dielectric etch stop layer 66 comprises a stack of a first dielectric etch stop layer 66A and a second dielectric etch stop layer 66B, the second dielectric etch stop layer 66B covering at least a portion of the first dielectric etch stop layer 66A and comprising a dielectric material different from the first dielectric etch stop layer 66A. In one embodiment, the first dielectric etch stop layer 66A comprises a silicon carbide layer, and / or is substantially composed of a silicon carbide layer, and the second dielectric etch stop layer 66B comprises silicon nitride or silicon oxynitride, and / or is substantially composed of silicon nitride or silicon oxynitride. In one embodiment, the second dielectric etch stop layer 66B may be substantially composed of silicon nitride. In another embodiment, the second dielectric etch stop layer 66B may be substantially composed of silicon oxynitride comprising nitrogen atoms at an atomic concentration greater than 10% (e.g., between 15% and 50%). The thickness of the first dielectric etch stop layer 66A can be in the range of 20 nm to 150 nm, such as between 30 nm and 70 nm, although smaller and larger thicknesses can also be used. The thickness of the second dielectric etch stop layer 66B can be in the range of 20 nm to 150 nm, such as between 30 nm and 70 nm, although smaller and larger thicknesses can also be used.

[0087] Each of the first dielectric etch stop layer 66A and the second dielectric etch stop layer 66B can be formed as a blanket material layer, i.e., an unpatterned material layer with a uniform thickness over the entire region of the respective material layer. In one embodiment, each of the first dielectric etch stop layer 66A and the second dielectric etch stop layer 66B can be deposited using a corresponding chemical vapor deposition process. In embodiments where etching occurs through any portion of the second dielectric etch stop layer 66B during subsequent anisotropic etch processes, the first dielectric etch stop layer 66A acts as an additional etch stop structure. Each of the first dielectric etch stop layer 66A and the second dielectric etch stop layer 66B extends continuously over the entire region of the silicon grating structure 30 with a corresponding uniform thickness.

[0088] After forming the first dielectric etch stop layer 66A and the second dielectric etch stop layer 66B, a passivation dielectric layer 70 can be formed. Subsequently, the following can be performed: Figure 2B , Figure 2C and Figure 2D The processing steps are provided to offer Figure 3A The structure is illustrated in the diagram. The passivation dielectric layer 70 extends continuously within the opening 69 and has a thickness within the opening 69 ranging from 1 nm to 200 nm. The thickness of the portion of the passivation dielectric layer 70 within the opening 69 may be uniform or non-uniform.

[0089] Figure 3BThis is a vertical cross-sectional view of an alternative embodiment of a second configuration of an exemplary optical structure according to an embodiment of this disclosure. A dielectric material portion 70R, comprising the dielectric material of a passivation dielectric layer 70, is positioned on the top surface of a single dielectric etch stop layer 66 at the central region of the opening 69, and is laterally spaced from and does not contact the sidewalls of the opening in the passivation dielectric layer 70. Therefore, a discrete portion of dielectric material, not physically connected to the passivation dielectric layer 70, can be formed at the central portion of the opening 69. The discrete portion of dielectric material may have a variable thickness, ranging from 1 nm to 200 nm. The dielectric material portion 70R in the opening 69 may have the same material composition as the flat portion of the passivation dielectric layer 70 having a uniform thickness (the initial thickness).

[0090] Figure 4A This is a vertical cross-sectional view of a fourth configuration of an exemplary optical structure according to an embodiment of this disclosure. A fourth configuration of the exemplary optical structure can be derived from the second configuration of the exemplary optical structure by patterning the second dielectric etch stop layer 66B. Specifically, the second dielectric etch stop layer 66B can be deposited as a blanket material layer, and a photoresist layer (not shown) can be coated and patterned over the second dielectric etch stop layer 66B to cover portions of the second dielectric etch stop layer 66B. The area of ​​the second dielectric etch stop layer 66B covered with the patterned photoresist layer may include the entire area of ​​the passivated dielectric layer 70 where the opening 69 will subsequently be formed.

[0091] Subsequently, it can be executed Figure 2B , Figure 2C and Figure 2D The processing steps are provided to offer Figure 4A The structure is illustrated in the diagram. The passivation dielectric layer 70 extends continuously within the opening 69 and has a thickness within the opening 69 ranging from 1 nm to 200 nm. The thickness of the portion of the passivation dielectric layer 70 within the opening 69 may be uniform or non-uniform.

[0092] Figure 4B This is a vertical cross-sectional view of an alternative embodiment of a fourth configuration of an exemplary optical structure according to an embodiment of this disclosure. A dielectric material portion 70R, including the dielectric material of the passivation dielectric layer 70, is positioned on the top surface of a single dielectric etch stop layer 66 at the central region of the opening 69, and is laterally spaced from and does not contact the sidewalls of the opening in the passivation dielectric layer 70. Therefore, a discrete portion of dielectric material, not physically connected to the passivation dielectric layer 70, can be formed at the central portion of the opening 69. The discrete portion of dielectric material may have a variable thickness, ranging from 1 nm to 200 nm. The dielectric material portion 70R in the opening 69 may have the same material composition as the flat portion of the passivation dielectric layer 70 having a uniform thickness (the initial thickness).

[0093] Figure 4C According to an embodiment of this disclosure Figure 4A or Figure 4B A plan view of a fourth configuration of the exemplary optical structure. A first dielectric etch stop layer 66A extends continuously over the entire region of the silicon grating structure 30, and a second dielectric etch stop layer 66B includes a periphery laterally surrounding the region defined by the sidewall 69S of the opening 69. At least one segment of the periphery of the second dielectric etch stop layer 66B spans the silicon grating structure 30.

[0094] Figure 5A This is a vertical cross-sectional view of a fourth configuration of an exemplary optical structure according to an embodiment of this disclosure. The fourth configuration of the exemplary optical structure can be derived from the second configuration of the exemplary optical structure by patterning a first dielectric etch-stop layer 66A. Specifically, the first dielectric etch-stop layer 66A can be deposited as a blanket material layer, and a photoresist layer (not shown) can be coated and patterned over a second dielectric etch-stop layer 66B to cover a portion of the first dielectric etch-stop layer 66A. The area of ​​the first dielectric etch-stop layer 66A covered with the patterned photoresist layer may include the entire area of ​​the passivated dielectric layer 70 where the opening 69 will subsequently be formed. Subsequently, a second dielectric etch-stop layer 66B can be formed over the first dielectric etch-stop layer 66A. The second dielectric etch-stop layer 66B may contact the surface of the first dielectric etch-stop layer 66A, and a portion of the topmost surface of at least one dielectric material layer 60.

[0095] Subsequently, it can be executed Figure 2B , Figure 2C and Figure 2D The processing steps are provided to offer Figure 5A The structure is illustrated in the diagram. The passivation dielectric layer 70 extends continuously within the opening 69 and has a thickness within the opening 69 ranging from 1 nm to 200 nm. The thickness of the portion of the passivation dielectric layer 70 within the opening 69 may be uniform or non-uniform.

[0096] Figure 5BThis is a vertical cross-sectional view of an alternative embodiment of a fourth configuration of an exemplary optical structure according to an embodiment of this disclosure. A dielectric material portion 70R, including the dielectric material of the passivation dielectric layer 70, is positioned on the top surface of a single dielectric etch stop layer 66 at the central region of the opening 69, and is laterally spaced from and does not contact the sidewalls of the opening in the passivation dielectric layer 70. Therefore, a discrete portion of dielectric material, not physically connected to the passivation dielectric layer 70, can be formed at the central portion of the opening 69. The discrete portion of dielectric material may have a variable thickness, ranging from 1 nm to 200 nm. The dielectric material portion 70R in the opening 69 may have the same material composition as the flat portion of the passivation dielectric layer 70 having a uniform thickness (the initial thickness).

[0097] Figure 5C According to an embodiment of this disclosure Figure 5A or Figure 5B A plan view of a fourth configuration of the exemplary optical structure. A first dielectric etch stop layer 66A includes a periphery laterally surrounding a region defined by the sidewalls 69S of the opening 69 in the passivated dielectric layer 70. At least one segment of the periphery of the first dielectric etch stop layer 66A spans the silicon grating structure 30. A second dielectric etch stop layer 66B extends continuously over the entire region of the silicon grating structure 30.

[0098] Figure 6A This is a vertical cross-sectional view of a fifth configuration of an exemplary optical structure according to an embodiment of this disclosure after the formation of a first patterned dielectric etch stop layer 66A. The fifth configuration of the exemplary optical structure can be derived from a second configuration of the exemplary optical structure by patterning the first dielectric etch stop layer 66A. Specifically, the first dielectric etch stop layer 66A can be deposited as a blanket material layer, and a photoresist layer (not shown) can be coated and patterned over a second dielectric etch stop layer 66B to form an opening in the photoresist layer within the passivation dielectric layer 70 for the subsequent formation of the opening 69. Regions of the first dielectric etch stop layer 66A not covered by the patterned photoresist layer can be integrally positioned within the entire region of the subsequent formation of the opening 69 in the passivation dielectric layer 70. An etching process (such as an anisotropic etching process or an isotropic etching process) can be performed to etch the unmasked portions of the first dielectric etch stop layer 66A. The patterned photoresist layer can be removed, for example, by ashing. Subsequently, a second dielectric etch stop layer 66B may be formed over the first dielectric etch stop layer 66A. The second dielectric etch stop layer 66B may contact the surface of the first dielectric etch stop layer 66A and a portion of the topmost surface of at least one dielectric material layer 60.

[0099] Figure 6BThis is a vertical cross-sectional view of a fifth configuration of an exemplary optical structure according to an embodiment of this disclosure after the formation of a second patterned dielectric etch-stop layer 66B. A second dielectric etch-stop layer 66B may be deposited over a first dielectric etch-stop layer 66A as a blanket material layer. The second dielectric etch-stop layer 66B may contact the topmost surface of at least one dielectric material layer 60 in the region of an opening in the first dielectric etch-stop layer 66A. A photoresist layer (not shown) may be coated and patterned over the second dielectric etch-stop layer 66B to cover a portion of the second dielectric etch-stop layer 66B. The region of the second dielectric etch-stop layer 66B covered with the patterned photoresist layer may include the entire region of the passivated dielectric layer 70 where the opening 69 will subsequently be formed. The periphery of the patterned second dielectric etch-stop layer 66B may be laterally offset outward from the periphery of the region in the passivated dielectric layer 70 where the opening 69 will subsequently be formed.

[0100] Reference Figure 6C Executable Figure 2B , Figure 2C and Figure 2D The processing steps are provided to offer Figure 6C The structure is illustrated in the diagram. A passivation dielectric layer 70 extends continuously within an opening 69 and has a thickness within the opening 69 ranging from 1 nm to 200 nm. The thickness of the passivation dielectric layer 70 within the opening 69 may be uniform or non-uniform. The combination of a first dielectric etch stop layer 66A and a second etch stop layer 66B provides an increased amount of etch stop material at the periphery of the opening 69 in the passivation dielectric layer 70. Typically, the peripheral portion of the opening 69 is a region where over-etching to the dielectric etch stop layers (66A, 66B) occurs. In embodiments where etching passes through the dielectric etch stop layers (66A, 66B), the dielectric material of at least one dielectric material layer 60 may be etched to provide an etch profile of degraded optical coupling between the silicon grating structure 30 and the optical fiber 80. Therefore, the presence of a first dielectric etch stop layer 66A and a second etch stop layer 66B around the opening 69 in the passivation dielectric layer 70 reduces the probability of etching through at least one dielectric etch stop layer 66, thereby reducing the probability of forming an optically harmful etch profile of the opening 69 in the passivation dielectric layer 70.

[0101] Figure 6DThis is a vertical cross-sectional view of an alternative embodiment of a fifth configuration of an exemplary optical structure according to an embodiment of this disclosure, after the patterned etch mask layer 77 and the attached optical fiber 80 have been removed. A dielectric material portion 70R, comprising the dielectric material of the passivation dielectric layer 70, is positioned on the top surface of a single dielectric etch stop layer 66 in the central region of the opening 69, and is laterally spaced from and does not contact the sidewalls of the opening in the passivation dielectric layer 70. Therefore, a discrete portion of dielectric material, not physically connected to the passivation dielectric layer 70, can be formed at the central portion of the opening 69. The discrete portion of dielectric material may have a variable thickness, ranging from 1 nm to 200 nm. The dielectric material portion 70R in the opening 69 may have the same material composition as the flat portion of the passivation dielectric layer 70 having a uniform thickness (the initial thickness).

[0102] Figure 6E According to an embodiment of this disclosure Figure 6C or Figure 6D A plan view of a fifth configuration of an exemplary optical structure. A first dielectric etch stop layer 66A includes an opening and has a periphery located within a region defined by the sidewall 69S of the opening 69 in the passivated dielectric layer 70, and a second dielectric etch stop layer 66B has a periphery located outside the region defined by the sidewall 69S of the opening 69 in the passivated dielectric layer 70, and does not include any opening within the periphery of the second dielectric etch stop layer 66B.

[0103] Figure 7A This is a vertical cross-sectional view of a sixth configuration of an exemplary optical structure according to an embodiment of this disclosure after forming an opening 69 through a passivation dielectric layer 70. A sixth configuration of the exemplary optical structure can be derived from a second exemplary optical structure by patterning a first dielectric etch stop layer 66A and a second dielectric etch stop layer 66B. Specifically, the first dielectric etch stop layer 66A can be patterned to cover the entire area of ​​the opening 69 that will subsequently be formed in the passivation dielectric layer 70. In this embodiment, the first dielectric etch stop layer 66A may have a periphery positioned outside the periphery of the opening 69 in the passivation dielectric layer 70, and does not include any opening within the periphery of the first dielectric etch stop layer 66A. The second dielectric etch stop layer 66B can be patterned to form an opening in the region of the opening 69 in the passivation dielectric layer 70. The second dielectric etch stop layer 66B may include an opening, having a periphery positioned in the region of the opening 69 in the passivation dielectric layer 70.

[0104] Subsequently, it can be executed Figure 2B , Figure 2C and Figure 2D The processing steps are provided to offer Figure 7AThe structure is illustrated in the diagram. A passivation dielectric layer 70 extends continuously within an opening 69 and has a thickness within the opening 69 ranging from 1 nm to 200 nm. The thickness of the passivation dielectric layer 70 within the opening 69 may be uniform or non-uniform. The combination of a first dielectric etch stop layer 66A and a second etch stop layer 66B provides an increased amount of etch stop material at the periphery of the opening 69 in the passivation dielectric layer 70. Typically, the peripheral portion of the opening 69 is a region where over-etching to the dielectric etch stop layers (66A, 66B) occurs. In embodiments where etching passes through the dielectric etch stop layers (66A, 66B), the dielectric material of at least one dielectric material layer 60 may be etched to provide an etch profile that degrades the optical coupling between the silicon grating structure 30 and the optical fiber 80. Therefore, the presence of a first dielectric etch stop layer 66A and a second etch stop layer 66B around the opening 69 in the passivation dielectric layer 70 reduces the probability of etching through at least one dielectric material layer 60, thereby reducing the probability of forming an optically harmful etch profile of the opening 69 in the passivation dielectric layer 70.

[0105] Figure 7B This is a vertical cross-sectional view of an alternative embodiment of a sixth configuration of an exemplary optical structure according to an embodiment of this disclosure, after the patterned etch mask layer 77 and the attached optical fiber 80 have been removed. A dielectric material portion 70R, comprising the dielectric material of the passivation dielectric layer 70, is positioned on the top surface of a single dielectric etch stop layer 66 in the central region of the opening 69, and is laterally spaced from and does not contact the sidewalls of the opening in the passivation dielectric layer 70. Therefore, a discrete portion of dielectric material, not physically connected to the passivation dielectric layer 70, can be formed at the central portion of the opening 69. The discrete portion of dielectric material may have a variable thickness, ranging from 1 nm to 200 nm. The dielectric material portion 70R in the opening 69 may have the same material composition as the flat portion of the passivation dielectric layer 70 having a uniform thickness (the initial thickness).

[0106] Figure 7C According to an embodiment of this disclosure Figure 7A or Figure 7B A plan view of a sixth configuration of an exemplary optical structure. A first dielectric etch stop layer 66A has a periphery located outside the region defined by the sidewall of the opening 69 in the passivated dielectric layer 70, and does not include any opening within the periphery of the first dielectric etch stop layer 66A, and a second dielectric etch stop layer 66B includes an opening, and the second dielectric etch stop layer 66B has a periphery located within the region defined by the sidewall of the opening 69 in the passivated dielectric layer 70.

[0107] Figure 8This is a vertical cross-sectional view of an exemplary semiconductor die 100 of this disclosure after attachment of optical fiber 80, according to an embodiment of this disclosure. Semiconductor die 100 may be incorporated into... Figure 1 An exemplary optical structure is provided. An optical molding structure 84 can be used to attach optical fibers 80 to a semiconductor die 100, which is an optical semiconductor die including at least one silicon photonic device 50 and at least one silicon grating structure 30. An array of solder balls 150 can be used to attach the semiconductor die 100 to a packaging substrate 200, which may include pins 250 for attachment to a circuit board, or another array of solder balls (such as C4 balls) can be used for attachment to a circuit board.

[0108] Common Reference Figures 1 to 8 Furthermore, according to various embodiments of this disclosure, a semiconductor structure including a semiconductor die 100 and an optical fiber 80 is provided. The semiconductor die 100, from bottom to top, includes a silicon substrate 10, a buried insulating layer 20, a silicon grating structure 30, at least one dielectric material layer 60, at least one dielectric etch stop layer 66, and a passivation dielectric layer 70. The passivation dielectric layer 70 includes a dielectric material and includes an opening 69 covering the end portion of the silicon grating structure 30. The optical fiber 80 covers the opening 69 in the passivation dielectric layer 70 and is optically coupled to the silicon grating structure 30 through the opening 69 in the passivation dielectric layer 70, and is attached to the semiconductor die 100 via an optical molding structure 84. The at least one dielectric material layer 60 includes at least one dielectric material selected from silicon nitride and silicon oxynitride.

[0109] In one embodiment, the silicon grating structure 30 includes a one-dimensional periodic array of silicon wiring structures 32 coupled to the top surface of a silicon substrate, wherein the distal end of the silicon substrate is tapered to provide a variable width that decreases with lateral distance from the one-dimensional periodic array of silicon wiring structures 32.

[0110] In one embodiment, at least one dielectric etch stop layer 66 includes a stack of a first dielectric etch stop layer 66A and a second dielectric etch stop layer 66B, wherein the second dielectric etch stop layer 66B covers at least a portion of the first dielectric etch stop layer 66A and includes a dielectric material different from the first dielectric etch stop layer 66A.

[0111] Figure 9 This is a flowchart illustrating the steps of forming an optical structure according to an embodiment of this disclosure. Referring to step 910 and... Figure 1 A silicon grating structure 30 can be formed on the embedded insulating layer 20. Refer to step 920 and... Figure 1 , Figure 2A , Figure 2E , Figure 3A , Figure 3B , Figure 4A , Figure 4B , Figure 5A , Figure 5B , Figure 6A , Figure 6D , Figure 7A and Figure 7B At least one dielectric material layer 60 may be deposited on the silicon grating structure 30. Referring to step 930 and... Figure 1 , Figure 2A , Figure 2E , Figure 3A , Figure 3B , Figure 4A , Figure 4B , Figure 5A , Figure 5B , Figure 6A , Figure 6B , Figure 6D , Figure 7A and Figure 7B At least one dielectric etch stop layer 66 may be deposited over at least one dielectric material layer 60. The at least one dielectric etch stop layer 66 comprises at least one dielectric material selected from silicon nitride and silicon oxynitride. Refer to step 940 and... Figure 1 , Figure 2A , Figure 2E , Figure 3A , Figure 3B , Figure 4A , Figure 4B , Figure 5A , Figure 5B , Figure 6C , Figure 6D , Figure 7A and Figure 7B A passivation dielectric layer 70 comprising a dielectric material may be formed over at least one dielectric etch stop layer 66. Refer to step 950 and... Figure 1 , Figure 2B , Figure 2E , Figure 3A , Figure 3B , Figure 4A , Figure 4B , Figure 5A , Figure 5B , Figure 6C , Figure 6D , Figure 7A and Figure 7B A patterned etch mask layer 77 can be formed on the passivation dielectric layer 70. The patterned etch mask layer 77 includes openings in the region at the end portions of the overlying silicon grating structure 30. Refer to step 960 and... Figure 1 , Figure 2C , Figure 2E , Figure 3A , Figure 3B , Figure 4A , Figure 4B , Figure 5A, Figure 5B , Figure 6C , Figure 6D , Figure 7A and Figure 7B An opening 69 can be formed through the unmasked portion of the passivated dielectric layer 70 by performing an anisotropic etching process. The anisotropic etching process etches a dielectric material selective to silicon nitride or silicon oxynitride by using a patterned etch mask layer 77 as a mask structure. Subsequently, the patterned etch mask layer 77 can be removed, and an optical fiber 80 can be disposed above the opening 69 in the passivated dielectric layer 70.

[0112] At least one dielectric etch stop layer 66 of this disclosure comprises a silicon nitride layer or a silicon oxynitride layer, which can advantageously serve as a highly efficient etch stop layer during anisotropic etching processes that form an opening 69 through a passivation dielectric layer 70. The ideal etch profile of the opening 69 is such that the opening 69 does not extend perpendicularly through the etch stop dielectric layer 66 and does not etch at least one dielectric material layer 60. The etch stop dielectric layer 66 prevents the opening from extending to at least one dielectric material layer 60 by utilizing a dielectric material different from the dielectric material of the passivation dielectric layer 70. The chemicals of the anisotropic etching process can be selected such that the etch rate of the material etched into the etch stop dielectric layer 66 during the anisotropic etching process is less than 30% of the etch rate of the dielectric material of the passivation dielectric layer 70, and preferably less than 10%, and even more significantly less than 3%. In some embodiments, the etching resistance of at least one dielectric etch stop layer 66 may increase only around the periphery of the opening 69 in the passivated dielectric layer 70, while providing only one of the first dielectric etch stop layer 66A and the second dielectric etch stop layer 66B at the central region through the opening 69 of the passivated dielectric layer 70 by patterning one or both of the first dielectric etch stop layer 66A and the second dielectric etch stop layer 66B. In this embodiment, the presence of only one of the first dielectric etch stop layer 66A and the second dielectric etch stop layer 66B at the central region through the opening 69 of the passivated dielectric layer 70 can reduce the optical effect of at least one dielectric etch stop layer (66A, 66B) by reducing the thickness of at least one dielectric etch stop layer (66A, 66B) at the central region through the opening 69 of the passivated dielectric layer 70.

[0113] In some embodiments, an optical structure includes a silicon grating structure, at least one dielectric material layer, at least one dielectric etch stop layer, a passivation dielectric layer, and optical fibers. The silicon grating structure is positioned on a buried insulating layer. At least one dielectric material layer covers and contacts the silicon grating structure. At least one dielectric etch stop layer covers at least one dielectric material layer and includes at least one dielectric material selected from silicon nitride and silicon oxynitride. The passivation dielectric layer includes dielectric material and covers at least one dielectric etch stop layer, and includes an opening covering an end portion of the silicon grating structure, wherein the opening does not contain the dielectric material of the passivation dielectric layer, or the opening includes the dielectric material of a passivation dielectric layer of a thickness less than 10% of the thickness of the passivation dielectric layer outside the opening. The optical fibers cover the opening in the passivation dielectric layer and include an end surface for receiving or emitting light directed to the opening in the passivation dielectric layer.

[0114] In some embodiments, at least one dielectric etch stop layer includes a stack of a first dielectric etch stop layer and a second dielectric etch stop layer, wherein the second dielectric etch stop layer covers at least a portion of the first dielectric etch stop layer and includes a dielectric material different from the first dielectric etch stop layer.

[0115] In some embodiments, the first dielectric etch stop layer comprises a silicon carbide layer; and the second dielectric etch stop layer comprises silicon nitride or silicon oxynitride.

[0116] In some embodiments, each of the first dielectric etch stop layer and the second dielectric etch stop layer extends continuously over the entire region of the silicon grating structure.

[0117] In some embodiments, the first dielectric etch stop layer extends continuously over the entire region of the silicon grating structure; and the second dielectric etch stop layer includes a periphery laterally surrounding a region defined by sidewalls of openings in the passivated dielectric layer, wherein at least one segment of the periphery spans the silicon grating structure.

[0118] In some embodiments, the first dielectric etch stop layer includes a periphery laterally surrounding a region defined by the sidewalls of an opening in the passivated dielectric layer, wherein at least one segment of the periphery spans the silicon grating structure; and the second dielectric etch stop layer extends continuously over the entire region of the silicon grating structure.

[0119] In some embodiments, the first dielectric etch stop layer includes an opening and has a periphery located within a region defined by the sidewalls of the opening in the passivated dielectric layer; and the second dielectric etch stop layer has a periphery located outside the region defined by the sidewalls of the opening in the passivated dielectric layer, and does not include any opening within the periphery of the second dielectric etch stop layer.

[0120] In some embodiments, the first dielectric etch stop layer has a periphery located outside the region defined by the sidewalls of the opening in the passivated dielectric layer, and does not include any opening within the periphery of the first dielectric etch stop layer; and the second dielectric etch stop layer includes an opening, the second dielectric etch stop layer having a periphery located within the region defined by the sidewalls of the opening in the passivated dielectric layer.

[0121] In some embodiments, at least one dielectric etch stop layer includes a single dielectric etch stop layer having a homogeneous material composition and contacting a flat top surface of at least one dielectric material layer and a bottom surface of a passivated dielectric layer over the entire area of ​​the silicon grating structure.

[0122] In some embodiments, at least one dielectric layer includes a first silicon oxide layer, a contact etch stop pad, and a second silicon oxide layer. The first silicon oxide layer contacts the silicon grating structure. The first silicon oxide layer covers the contact etch stop pad. The second silicon oxide layer contacts the contact etch stop pad.

[0123] In some embodiments, a portion of the dielectric material including the dielectric material of the passivation dielectric layer is positioned on the top surface of at least one dielectric etch stop layer in the central region of the opening, and is laterally spaced from and does not contact the sidewalls of the opening in the passivation dielectric layer.

[0124] In some embodiments, the passivation dielectric layer extends continuously within the opening and has a thickness in the range of 1 nm to 200 nm, and has a thickness in the range of 3 μm to 30 μm outside the opening in the passivation dielectric layer.

[0125] In some embodiments, a semiconductor structure includes a semiconductor die and optical fibers. The semiconductor die, from bottom to top, includes a silicon substrate, a buried insulating layer, a silicon grating structure, at least one dielectric material layer, at least one dielectric etch stop layer, and a passivation dielectric layer. The passivation dielectric layer includes a dielectric material and includes an opening at the end portion of the silicon grating structure. The optical fibers are covered by the opening in the passivation dielectric layer and are optically coupled to the silicon grating structure through the opening in the passivation dielectric layer, and are attached to the semiconductor die via an optical molding structure. The at least one dielectric material layer includes at least one dielectric material selected from silicon nitride and silicon oxynitride.

[0126] In some embodiments, the silicon grating structure includes a one-dimensional periodic array of silicon wiring structures coupled to the top surface of a silicon substrate, wherein the distal end of the silicon substrate is tapered to provide a variable width that decreases with lateral distance from the one-dimensional periodic array of silicon wiring structures.

[0127] In some embodiments, at least one dielectric etch stop layer includes a stack of a first dielectric etch stop layer and a second dielectric etch stop layer, wherein the second dielectric etch stop layer covers at least a portion of the first dielectric etch stop layer and includes a dielectric material different from the first dielectric etch stop layer.

[0128] In some embodiments, a method of forming an optical structure includes the following operations: forming a silicon grating structure over an embedded insulating layer; depositing at least one dielectric material layer over the silicon grating structure; depositing at least one dielectric etch stop layer over the at least one dielectric material layer, wherein the at least one dielectric etch stop layer comprises at least one dielectric material selected from silicon nitride and silicon oxynitride; forming a passivation dielectric layer comprising a dielectric material over the at least one dielectric etch stop layer; forming a patterned etch mask layer over the passivation dielectric layer, wherein the patterned etch mask layer includes an opening in a region covering the end portion of the silicon grating structure; forming the opening through the unmasked portion of the passivation dielectric layer by performing an anisotropic etching process, the anisotropic etching process etching a dielectric material selective to silicon nitride or silicon oxynitride by using the patterned etch mask layer as a mask structure.

[0129] In some embodiments, the passivation dielectric layer has a passivation dielectric layer thickness prior to the anisotropic etching process. The duration of the anisotropic etching process is selected such that the opening contains no dielectric material with a passivation dielectric layer, or the opening includes a dielectric material with a passivation dielectric layer of a thickness less than 10% of the thickness of the passivation dielectric layer.

[0130] In some embodiments, the method of forming an optical structure further includes disposing optical fibers over an opening in a passivated dielectric layer, wherein the optical fibers include end surfaces for receiving or emitting light directed to the opening in the passivated dielectric layer.

[0131] In some embodiments, at least one dielectric etch stop layer includes a stack of a first dielectric etch stop layer and a second dielectric etch stop layer, wherein the second dielectric etch stop layer covers at least a portion of the first dielectric etch stop layer and includes a dielectric material different from the first dielectric etch stop layer.

[0132] In some embodiments, the first dielectric etch stop layer comprises a silicon carbide layer. The second dielectric etch stop layer comprises silicon nitride or silicon oxynitride.

[0133] The foregoing outlines features of several embodiments to enable those skilled in the art to better understand the various aspects of this disclosure. Those skilled in the art should understand that they can readily use this disclosure as a basis for designing or modifying other processes and structures to achieve the same purposes and / or benefits as the embodiments described herein. Those skilled in the art should also recognize that such equivalent constructions do not depart from the spirit and scope of this disclosure, but rather various changes, substitutions, and modifications can be made without departing from the spirit and scope of this disclosure.

Claims

1. An optical structure, characterized by, include: A silicon grating structure positioned on an embedded insulating layer; At least one dielectric material layer, which covers and contacts the silicon grating structure; A stacked layer includes a first dielectric etch stop layer and a second dielectric etch stop layer, the stacked layer covering the at least one dielectric material layer, wherein one of the first dielectric etch stop layer and the second dielectric etch stop layer includes a dielectric material selected from silicon nitride and silicon oxynitride, and the second dielectric etch stop layer includes a dielectric material different from the first dielectric etch stop layer. A passivation dielectric layer comprising a dielectric material and covering the layer stack, and including an opening covering an end portion of the silicon grating structure, wherein the opening does not contain the dielectric material of the passivation dielectric layer, or the opening includes the dielectric material of the passivation dielectric layer of a thickness, wherein the thickness is less than 10% of the thickness of the passivation dielectric layer outside the opening; as well as An optical fiber, the optical fiber being covered by the opening in the passivated dielectric layer and including an end surface for receiving or emitting light directed into the opening in the passivated dielectric layer, wherein: The stacked layers are separated from the opening by a portion of the passivated dielectric layer and are not exposed through the opening, or One of the first dielectric etch stop layer and the second dielectric etch stop layer is exposed through the opening, while the other of the first dielectric etch stop layer and the second dielectric etch stop layer is not exposed through the opening.

2. The optical structure according to claim 1, characterized in that: The first dielectric etch stop layer includes a silicon carbide layer; and The second dielectric etch stop layer comprises silicon nitride or silicon oxynitride.

3. The optical structure of claim 1, wherein, Each of the first dielectric etch stop layer and the second dielectric etch stop layer extends continuously over an entire region of the silicon grating structure.

4. The optical structure according to claim 1, characterized in that: The first dielectric etch stop layer extends continuously over an entire region of the silicon grating structure; and The second dielectric etch stop layer includes a periphery laterally surrounding a region defined by the sidewalls of the opening in the passivated dielectric layer, wherein at least one segment of the periphery spans the silicon grating structure.

5. The optical structure according to claim 1, characterized in that: The first dielectric etch stop layer includes a periphery laterally surrounding a region defined by the sidewalls of the opening in the passivated dielectric layer, wherein at least one segment of the periphery spans the silicon grating structure; and The second dielectric etch stop layer extends continuously over an entire area of ​​the silicon grating structure.

6. The optical structure according to claim 1, characterized in that: The first dielectric etch stop layer includes an opening, and the first dielectric etch stop layer has a periphery located in a region defined by the sidewall of the opening in the passivated dielectric layer; as well as The second dielectric etch stop layer has a periphery located outside the region defined by the sidewall of the opening in the passivated dielectric layer, and does not include any opening within the periphery of the second dielectric etch stop layer.

7. The optical structure according to claim 1, characterized in that: The first dielectric etch stop layer has a periphery located outside a region defined by the sidewall of the opening in the passivation dielectric layer, and does not include any opening within the periphery of the first dielectric etch stop layer; and The second dielectric etch stop layer includes an opening and has a periphery located within the region defined by the sidewalls of the opening in the passivated dielectric layer.

8. The optical structure according to claim 1, characterized in that: The at least one dielectric material layer includes a first silicon oxide layer, a contact etch stop pad, and a second silicon oxide layer. The first silicon oxide layer contacts the silicon grating structure, the contact etch stop pad is covered by the first silicon oxide layer, and the second silicon oxide layer contacts the etch stop pad.

9. The optical structure of claim 1, wherein: Further, a portion of the dielectric material of the passivation dielectric layer is positioned on a top surface of the stacked layers at a central region of the opening, and is laterally spaced from and does not contact the sidewall of the opening in the passivation dielectric layer.

10. The optical structure according to claim 1, characterized in that: The passivation dielectric layer extends continuously within the opening and has a thickness in the range of 1 nm to 200 nm, and has a thickness in the range of 3 μm to 30 μm outside the opening in the passivation dielectric layer.

11. The optical structure according to claim 1, characterized in that: One of the first dielectric etch stop layer and the second dielectric etch stop layer has a first periphery defined by the opening of the passivation dielectric layer, one of the first dielectric etch stop layer and the second dielectric etch stop layer is located in a region within the first periphery, and the other of the first dielectric etch stop layer and the second dielectric etch stop layer is located in a region outside the first periphery.

12. The optical structure according to claim 11, characterized in that: The first dielectric etch stop layer and the other of the second dielectric etch stop layer each include an opening having a second periphery, and the other of the first dielectric etch stop layer and the second dielectric etch stop layer are located in a region outside the second periphery.

13. The optical structure according to claim 12, characterized in that: The second perimeter deviates laterally outward from the first perimeter.

14. A semiconductor structure comprising a semiconductor grain and an optical fiber, characterized in that, in: The semiconductor die, from bottom to top, includes a silicon substrate, a buried insulating layer, a silicon grating structure, at least one dielectric material layer, a stack of layers including a first dielectric etch stop layer and a second dielectric etch stop layer, and a passivation dielectric layer, which includes a dielectric material and includes an opening covering an end portion of the silicon grating structure. The optical fiber is covered by the opening in the passivation dielectric layer and is optically coupled to the silicon grating structure through the opening in the passivation dielectric layer, and is attached to the semiconductor die through an optical molding structure; as well as The at least one dielectric material layer comprises at least one dielectric material selected from silicon nitride and silicon oxynitride, wherein: One of the first dielectric etch stop layer and the second dielectric etch stop layer includes a dielectric material selected from silicon nitride and silicon oxynitride; The second dielectric etch stop layer comprises a dielectric material different from that of the first dielectric etch stop layer; Both the first dielectric etch stop layer and the second dielectric etch stop layer are disposed below a bottom surface of the opening; and One of the first dielectric etch stop layer and the second dielectric etch stop layer is perpendicularly spaced from the opening and is not exposed through the opening.

15. The semiconductor structure according to claim 14, characterized in that: The silicon grating structure includes a one-dimensional periodic array of silicon wiring structures coupled to a top surface of a silicon substrate, wherein a distal end of the silicon substrate is tapered to provide a variable width that decreases with a lateral distance from the one-dimensional periodic array of silicon wiring structures.

16. A method for forming an optical structure, characterized in that, include: A silicon grating structure is formed on an embedded insulating layer; At least one dielectric material layer is deposited on the silicon grating structure; A stack of layers including a first dielectric etch stop layer and a second dielectric etch stop layer is deposited on the at least one dielectric material layer, wherein one of the first dielectric etch stop layer and the second dielectric etch stop layer includes a dielectric material selected from silicon nitride and silicon oxynitride, and the second dielectric etch stop layer includes a dielectric material different from the first dielectric etch stop layer. A passivation dielectric layer comprising a dielectric material is formed on top of this layer stack; A patterned etch mask layer is formed on the passivation dielectric layer, wherein the patterned etch mask layer includes an opening in a region covering an end portion of the silicon grating structure; as well as An opening is formed by performing an anisotropic etching process through an unmasked portion of the passivated dielectric layer. This anisotropic etching process uses the patterned etch mask layer as a mask structure to etch the dielectric material, which is selective to silicon nitride or silicon oxynitride. The stacked layers are separated from the opening by a portion of the passivated dielectric layer and are not exposed through the opening, or One of the first dielectric etch stop layer and the second dielectric etch stop layer is exposed through the opening, while the other of the first dielectric etch stop layer and the second dielectric etch stop layer is not exposed through the opening.

17. The method according to claim 16, characterized in that: The passivation dielectric layer has a passivation dielectric layer thickness prior to the anisotropic etching process; and The duration of the anisotropic etching process is selected such that the opening does not contain the dielectric material of the passivation dielectric layer, or the opening includes the dielectric material of the passivation dielectric layer of a thickness, wherein the thickness is less than 10% of the thickness of the passivation dielectric layer.

18. The method according to claim 16, characterized in that: The method further includes disposing an optical fiber above the opening in the passivated dielectric layer, wherein the optical fiber includes an end surface for receiving or emitting light directed into the opening in the passivated dielectric layer.

19. The method according to claim 16, characterized in that: The first dielectric etch stop layer includes a silicon carbide layer, and the second dielectric etch stop layer includes silicon nitride or silicon oxynitride.

20. The method according to claim 16, characterized in that: One of the first dielectric etch stop layer and the second dielectric etch stop layer has a first periphery defined by the opening of the passivation dielectric layer, one of the first dielectric etch stop layer and the second dielectric etch stop layer is located in a region within the first periphery, and the other of the first dielectric etch stop layer and the second dielectric etch stop layer is located in a region outside the first periphery.

Images