Optical waveguide device and method for preparing the same

Abstract

The present invention relates to the technical field of optical waveguide preparation, and in particular to an optical waveguide device and a preparation method thereof, wherein the optical waveguide device comprises: a first structural layer, the first structural layer is provided with an optical waveguide, and a material layer is provided on the front side of the optical waveguide; a second structural layer connected to the first surface of the first structural layer, and a substrate layer connected to the second structural layer; the second structural layer and the substrate layer are provided with first and second grooves corresponding to the optical waveguide in sequence, a first guide portion is formed on the side wall of the first groove, a second guide portion with a first thickness is formed on the back side of the optical waveguide, the first and second guide portions are connected to form a back growth platform, and the cross-section of the back growth platform is a trapezoidal structure; a phase change material layer is provided on the back growth platform, and a protective layer is also formed on the third outer surface of the phase change material layer. The back growth method proposed by the present invention can reduce the influence on the material layer on the front side of the optical waveguide.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular to an optical waveguide device and a preparation method thereof. Background Art

[0002] Phase-Change Materials (PCMs) are intrinsically nonvolatile and have been widely used in photonic applications, including photonic memory devices, rewritable optical disks, optical filters, displays, and optical switches. PCMs can be easily deposited on any substrate using standard methods and can switch back and forth between amorphous and crystalline states at high speed and with long-term stability. The refractive index changes dramatically when switching between the amorphous and crystalline states. Compact optical switches with Ge2Sb2Te5 (GST) and Ge2Sb2Se4Te1 (GSST) on top of waveguide couplers have been demonstrated to have high switching speeds (100ns) and low power consumption. Therefore, PCM-based photonic devices have several advantages over traditional photonic switching schemes and are expected to be used to develop large-scale nonvolatile reprogrammable photonic routing systems, such as field programmable coupler arrays.

[0003] At present, the molding process of phase change material on optical waveguide is: processing is performed on the front side (i.e., the upper surface) of the optical waveguide to generate a phase change material layer on the front side. For example, patent application CN117706811A discloses an optical waveguide, which includes: an optical waveguide layer, a phase change material located on the optical waveguide layer, a first isolation layer is arranged between the optical waveguide layer and the phase change material, a first protective layer is covered on the phase change material, and also includes: a second isolation layer surrounding the first isolation layer and the phase change material, and a second protective layer surrounding the first protective layer, the second isolation layer, and the optical waveguide layer. In other words, the patent application adopts a process of opening a window above the optical waveguide layer to reduce damage to the optical waveguide layer while generating the phase change material. In addition, the scheme adopts a non-vertical etching method to reduce the difficulty of the sputtering process of the phase change material.

[0004] However, as the structure of the optical waveguide layer becomes more complicated, the existing window opening process may also be difficult to ensure the structural stability and reliability of the optical waveguide device. Summary of the invention

[0005] The object of the present invention is to provide an optical waveguide device and a method for manufacturing the same, which can partially solve or alleviate the above-mentioned deficiencies in the prior art and reduce the damage to the multilayer materials on the front side of the optical waveguide.

[0006] In order to solve the above-mentioned technical problems, the present invention specifically adopts the following technical solutions:

[0007] A first aspect of the present invention is to provide an optical waveguide device, comprising:

[0008] A first structural layer, wherein a first recessed area is formed on a first surface of the first structural layer, an optical waveguide is disposed in the first recessed area, and at least one material layer is disposed on a front surface of the optical waveguide;

[0009] a second structural layer connected to the first surface of the first structural layer, and a substrate layer connected to the second structural layer;

[0010] The second structural layer and the substrate layer are sequentially provided with a first slot and a second slot corresponding to the optical waveguide, a first guide portion is formed on the side wall of the first slot, and a second guide portion with a first thickness is formed on the back of the optical waveguide, wherein the first outer surface of the first guide portion is arranged in an inclined plane so that an angle α is formed between the plane where the first outer surface is located and the second outer surface of the second guide portion, and the angle α ranges from 80° to 90°; correspondingly, the first outer surface is connected to the second outer surface to form a back growth platform, and the cross-section of the back growth platform is a trapezoidal structure;

[0011] A phase change material layer is disposed on the back growth platform, and a protective layer is formed on the third outer surface of the phase change material layer.

[0012] In some embodiments, a gap space is formed between an edge of the third outer surface and the first outer surface and / or the second outer surface, and the protective material of the protective layer is embedded in the gap space.

[0013] In some embodiments, the angle α ranges from 85° to 90°;

[0014] In some embodiments, the width of the backside growth platform is less than or equal to the structure of the optical waveguide.

[0015] In some embodiments, the first thickness is 1 nm-200 nm.

[0016] In some embodiments, at least one metal layer is disposed in the first structural layer, and the metal layer is disposed adjacent to the optical waveguide.

[0017] In some embodiments, at least one of the material layers is a Ge material layer.

[0018] The present invention also provides a method for preparing an optical waveguide device, the method being used to prepare a narrow and long channel on an initial multilayer structure so as to grow a phase change material in the narrow and long channel; correspondingly, the method comprises the steps of:

[0019] S101, providing an initial multilayer structure, wherein the initial multilayer structure comprises: a first structure layer, a first recessed area is formed on a first surface of the first structure layer, an optical waveguide is arranged in the first recessed area, and at least one material layer is arranged on the front surface of the optical waveguide; a second structure layer is connected to the first surface of the first structure layer, and a substrate layer is connected to the second structure layer;

[0020] S102, thinning the substrate layer from the second thickness to a third thickness, and correspondingly forming a thinned layer;

[0021] S103, preparing a narrow and long channel corresponding to the optical waveguide on the current initial multilayer structure; wherein S103 includes:

[0022] S31, etching the thinned layer using a first etching method to form a second narrow groove on the thinned layer, so that at least a portion of the second structural layer is exposed through the second narrow groove, thereby correspondingly forming a first multi-layer structure;

[0023] S32, etching the second structural layer by a second etching method, so that a first narrow groove is formed on the second structural layer to form a second multilayer structure, wherein the first narrow groove and the second narrow groove form a narrow channel, at this time, a first guide portion is formed on the side wall of the first narrow groove, and a second guide portion with a first thickness is formed on the back side of the optical waveguide, wherein the first outer surface of the first guide portion is inclined, so that an angle α is formed between the plane where the first outer surface is located and the second outer surface of the second guide portion, and the angle range of the angle α is 80°-90°; correspondingly, the first outer surface is connected to the second outer surface to form a back growth platform, so that the cross-section of the back growth platform is a trapezoidal structure;

[0024] S104, growing a phase change material layer on a back growth platform in the narrow and long channel using a first growth method;

[0025] S105 , growing a protective layer on the phase change material layer using a second growth method to fill the narrow and long channel.

[0026] In some embodiments, before S103, the step further includes:

[0027] S106, etching at least two groups of the initial multilayer structures by a first etching method using at least two groups of different first etching conditions to form the second grooves on the substrate layer, so as to obtain at least two groups of the first multilayer structures; wherein the first etching conditions include: a first raw material component and a first etching time;

[0028] S107, collecting at least two groups of first etching results from at least two groups of the first multilayer structures, wherein the first etching results include: a second width X2 of the second groove, and a second depth H2 of the second groove;

[0029] S108, determining whether the first etching result meets a set first etching standard, and if so, recording the first etching result as a qualified result;

[0030] S109, selecting the first etching condition corresponding to the qualified result as the first recommended condition.

[0031] In some embodiments, the steps include:

[0032] S110, etching the second structural layer on the first multilayer structure by the second etching method using at least two sets of different second etching conditions, so as to correspondingly form the first narrow groove on the second structural layer and then form the second multilayer structure, wherein the first narrow groove and the second narrow groove are connected to form the narrow channel; wherein the second etching conditions include: a second raw material component and a second etching time;

[0033] S111, collecting at least two groups of second etching results from at least two groups of the second multilayer structures, wherein the second etching results include: a first thickness, and an angle α;

[0034] S112, performing step S104 and step S105 on at least two groups of the second multilayer structures respectively, so as to prepare at least two groups of optical waveguide devices;

[0035] S113, performing optical transmission tests on at least two groups of the optical waveguide devices, and collecting test results accordingly, the test results including: transmission efficiency of optical signals between the optical waveguide and the phase change material;

[0036] S114, determining whether the test result meets a preset transmission standard, and if so, selecting the second etching structure corresponding to the test result as a second recommended condition.

[0037] In some embodiments, the second etching method is dry etching or wet etching.

[0038] Beneficial technical effects:

[0039] The present invention proposes a technical solution of setting a narrow and long channel on the back side of an optical waveguide to grow a phase change material. This structure of growing the phase change material on the back side of the waveguide through the narrow and long channel can reduce the adverse effects of the growth process of the phase change material on the original structure, that is, on the one hand, it can avoid the effects on the multi-layer material layers on the front side of the waveguide, and on the other hand, the low-density distribution of the narrow and long channel can also reduce the damage caused by the back window opening to the wafer.

[0040] The backside growth platform proposed in the present invention helps to keep the phase change material working in a stable state during the growth and application process.

[0041] It is worth noting that, during the etching process, multiple process parameters such as etching gas flow, chamber pressure, RF power, temperature, etching time, solution concentration, etc. may have a certain impact on the etching results. In order to alleviate the damage that may be caused to the wafer by the back window opening process, and at the same time ensure that the narrow channel opened can more stably guide the growth of phase change materials, the present invention proposes a technical solution for selecting two key factors, etching raw materials and etching time, to control the etching speed to form a narrow channel on the wafer. Specifically, in the present invention, the etching raw materials and etching time are coordinated to form a narrow channel in a limited area on the wafer. On the one hand, the focus is on ensuring that a sufficiently deep etching can be completed, while controlling the reaction area of ​​the etching raw materials below the horizontal plane, thereby preparing a narrow channel with only a narrow opening on the back of the optical waveguide and capable of stably growing phase change materials.

[0042] Furthermore, in this embodiment, the modulation capability (specifically, the transfer efficiency) of the phase change material after the phase change material is grown on the narrow channel is used to evaluate the effectiveness of the narrow channel. In this regard, in order to improve the effectiveness of the narrow channel, the present invention selects two morphological data, such as the first thickness and the angle α of the back growth platform in the narrow channel, to conduct a targeted evaluation of the depth and bottom morphology of the narrow channel.

[0043] From another perspective, for this new back windowing process, the present invention selects two key factors, namely, etching raw materials and etching time, to control the etching speed, thereby being able to critically guide the core morphology of the narrow and long channel. That is, by quickly setting the limited factors, the recommended conditions suitable for the back windowing process are efficiently selected. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual scale. Obviously, the drawings described below are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without paying creative labor.

[0045] Figure 1 is a schematic structural diagram of a multilayer structure in an exemplary embodiment of the present invention;

[0046] Figure 2 is a schematic diagram of the structure of a multi-layer structure after etching in an exemplary embodiment of the present invention;

[0047] Figure 3 is a schematic structural diagram of a semiconductor device in an exemplary embodiment of the present invention;

[0048] Figure 4 is a schematic structural diagram of a semiconductor device in another exemplary embodiment of the present invention;

[0049] Figure 5 is a first structural schematic diagram of a semiconductor device in yet another exemplary embodiment of the present invention;

[0050] Figure 6 is a first structural schematic diagram of a semiconductor device in yet another exemplary embodiment of the present invention;

[0051] Figure 7 It is a schematic flow chart of a method for manufacturing a semiconductor device in an exemplary embodiment of the present invention.

[0052] Summary of reference numerals:

[0053] Optical waveguide 01, phase change material layer 02, back growth platform 03, first guide part 031, second guide part 032, protection layer 04, gap layer 041, cover layer 042, second structure layer 05, substrate layer 06, first structure layer 07, material layer 08, metal layer 09, narrow channel 10, first groove I, second groove II. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0055] Herein, suffixes such as "module", "component" or "unit" used to represent elements are only used to facilitate the description of the present invention, and have no specific meanings by themselves. Therefore, "module", "component" or "unit" can be used mixedly.

[0056] In this document, the terms "upper", "lower", "inner", "outer", "front", "back", "one end", "the other end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0057] In this document, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] Herein "and / or" includes any and all combinations of one or more of the associated listed items.

[0059] Herein, "plurality" means two or more than two, ie, it includes two, three, four, five, etc.

[0060] As used in this specification, the term "about" typically means + / - 5% of the stated value, more typically + / - 4% of the stated value, more typically + / - 3% of the stated value, more typically + / - 2% of the stated value, even more typically + / - 1% of the stated value, and even more typically + / - 0.5% of the stated value.

[0061] In this specification, some embodiments may be disclosed in a format of being in a range. It should be understood that this description of "being in a range" is only for convenience and brevity, and should not be interpreted as a rigid limitation on the disclosed range. Therefore, the description of the range should be considered to have specifically disclosed all possible sub-ranges and independent numerical values ​​within this range. For example, the description of the range 1-6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as individual numbers within this range, such as 1, 2, 3, 4, 5 and 6. Regardless of the breadth of the range, the above rules apply.

[0062] In this article, "long and narrow" means that the depth (or thickness, i.e., the length in a direction perpendicular or approximately perpendicular to the surface of the structure layer) of the structure is greater than the width of the structure. In particular, "long and narrow" means that the depth of the structure is much greater than the width of the structure. For example, see Figure 6 As shown, the depth of the narrow channel 10 (formed by the first slot I and the second slot II) is much greater than the width, such as the depth is more than twice the width, or even more than five times the width, or more than ten times the width.

[0063] In this article, "quasi-trapezoidal" refers to a quadrilateral with one set of opposite sides that are not parallel, and the other set of opposite sides that are relatively parallel or approximately parallel, wherein approximately parallel can be understood as the angle between the two lines or planes being very small, which can be considered to be close to zero degrees, but not necessarily completely zero (such as approximately 0.5°, approximately 1°, approximately 3°, etc.).

[0064] Herein, "light" refers to electromagnetic radiation or electromagnetic waves with a wavelength in the ultraviolet (UV) to infrared (IR) range (eg, between 10 nm and 100 μm), which can propagate in free space and be guided by a waveguide.

[0065] As used herein, an "optical waveguide layer" (or waveguide) refers to any structure used to confine light in one or more dimensions within or adjacent to its surface, thereby guiding light in a propagation direction parallel to its axis. A waveguide is formed by a series of layers / regions with different refractive indices, typically including an inner layer / region or a core layer / region. The inner layer / region or the core layer / region is made of a material with a higher refractive index than the surrounding (outer) layer / region or the cladding layer / region. In this case, the waveguide confines light in two dimensions, for example, within a channel, in the thickness / growth direction and in the lateral / width direction perpendicular to the thickness / growth direction. The core layer / region and / or the cladding layer / region may be referred to as a guiding layer that actively confines and guides light.

[0066] Herein, "modulation layer" refers to any entity that affects the properties of light, including transmission, refraction, absorption, etc. Preferably, the light modulation layer includes a phase change material layer made of a phase change material, or can be made of a phase change material.

[0067] Embodiment 1

[0068] In stark contrast to the existing approach of setting a modulation layer on the front side (i.e., the side away from the substrate) of the optical waveguide, the present invention proposes a technical approach of setting a modulation layer on the back side of the optical waveguide. The modulation layer set on the back side can reduce the impact on the original structure of the optical waveguide and the SiO2 cladding to a certain extent.

[0069] In particular, the growth of the phase change material on the back side does not affect the growth of the multilayer material on the front side, and the functionality (transmission, modulation, detection, etc.) of a single chip can be made more complete. On the contrary, the applicant has noticed that the growth of the phase change material on the front side may affect the growth of the Ge material, which is the core material for realizing different types of detection such as 1310nm and 1550nm. The structure of the semiconductor device with the back-grown phase change material is as follows: Figure 1-Figure 5 shown.

[0070] For example, see Figure 1 As shown, Figure 1 The cross-sectional structure diagram of the SiO2 cladding (equivalent to the first structural layer 07) is shown, in which the optical waveguide 01 is arranged, and the material layer 08 (for example, it can be a Ge material layer) is arranged on the front side of the optical waveguide 01, and two metal layers 09 are arranged in the SiO2 cladding near the optical waveguide 01. When the functional integration of the optical waveguide device is higher, the material layer formed in the front area of ​​the optical waveguide 01 will become more and more complex, and thus the process difficulty of depositing the phase change material on the front side will also increase.

[0071] In view of this, in order to prepare optical waveguide devices with increasingly higher functional integration, the present invention provides a new type of optical waveguide device structure, see Figure 3 As shown, it includes:

[0072] The first structural layer 07 has the optical waveguide 01 disposed thereon, and at least one material layer 08 is disposed on the front surface (also referred to as: upper surface) of the optical waveguide 01 .

[0073] A second structural layer 05 connected to the first surface of the first structural layer 07, and a substrate layer 06 connected to the second structural layer 05; wherein the second structural layer 05 and the substrate layer 06 are sequentially provided with a first slot I and a second slot II corresponding to the optical waveguide 01. Preferably, the first slot and the second slot are configured as a narrow first slot I and a narrow second slot II, and correspondingly, the narrow first slot or the second slot is also referred to as a narrow channel or is regarded as a part of a narrow channel.

[0074] A back growth platform 03 (such as a SiO2 layer) is provided on the back side (also referred to as the lower surface) of the optical waveguide. The back growth platform 03 is provided with a modulation layer (preferably a phase change material layer 02), and a protective layer is further provided on the modulation layer.

[0075] It is worth noting that the second structure layer 05 and the substrate layer 06 are preferably made of finished wafers, such as SOI wafers.

[0076] Furthermore, in order to improve the stability of the phase change material and minimize the damage to the wafer structure, it is preferred to use an optical waveguide device that can be prepared by a vertical etching method, see Figure 4 As shown, it includes:

[0077] A first structural layer 07, wherein a first recessed area is formed on a first surface of the first structural layer 07, and an optical waveguide 01 is disposed in the first recessed area, and at least one material layer 08 is disposed on the front surface of the optical waveguide 01;

[0078] a second structural layer 05 connected to the first surface of the first structural layer 07, and a substrate layer 06 connected to the second structural layer 05;

[0079] Among them, the first groove I and the second groove II corresponding to the optical waveguide 01 are sequentially arranged on the second structural layer 05 and the substrate layer 06, a first guide part 031 is formed on the side wall of the first groove, and a second guide part 032 with a first thickness is formed on the back side of the optical waveguide 01, wherein the first outer surface of the first guide part is arranged in an inclined surface so that an angle α is formed between the plane where the first outer surface is located and the second outer surface of the second guide part, and the range of the angle α is 80°-90°; correspondingly, the first outer surface is connected to the second outer surface to form a back growth platform, and the cross-section of the back growth platform is a trapezoidal structure; for example, the width of the back growth platform gradually increases in the direction away from the optical waveguide.

[0080] The back growth platform is provided with a phase change material layer 02, and a protective layer is formed on the third outer surface of the phase change material layer 02. Preferably, the side surface of the protective layer is in contact with the second outer surface to further increase the stability of the phase change material layer and the protective layer.

[0081] Preferably, the first guide portion 031 and the second guide portion 032 in this embodiment can be integrally formed by a vertical etching process.

[0082] Preferably, a vertical etching process is used to etch the second structural layer 05 to guide a portion of the second structural material (such as SiO2) to remain on the optical waveguide 01, and the remaining second structural material can form a back growth platform with a trapezoidal cross section.

[0083] Preferably, the second structural layer is SiO2box, the substrate layer is Si substrate, SiO2box and Si substrate are equivalent to SIO wafer, that is, the second structural layer and the substrate layer preferably use finished wafer. In this regard, the present invention actually provides a simple back growth structure (or, back window opening process), avoiding the setting of multiple stop layers and oxide layers, and can directly use the residue of the material layer of the finished wafer itself to set the guide part (or, back growth platform), which can reduce the damage to the wafer layer, make reasonable use of existing materials, and reduce consumables.

[0084] Preferably, see Figure 6 As shown, the first slot and the second slot are configured as a first elongated slot I and a second elongated slot II, that is, the first depth H1 of the first slot is greater than the first width X1, and the second depth H2 of the second slot II is greater than the second width X2.

[0085] Preferably, the second depth H2 is twice or more than the second width X2. Preferably, the second depth H2 is three times or more than the second width X2. Preferably, the second depth H2 is three times or more than the second width X2.

[0086] For example, in some embodiments, the second depth H2 of the second trench is about 50 μm, and the second width X2 is about 10 μm.

[0087] Preferably, in some embodiments, the distribution density of the opening area of ​​the second slots in the substrate layer (also equivalent to the distribution density of the narrow and long channels) is less than or equal to about 0.03%, where distribution density = opening area × number of openings / area of ​​the substrate layer.

[0088] This embodiment proposes, on the one hand, a setting of multiple narrow channels with low density characteristics (i.e., the distribution density of the narrow channels on the wafer is relatively small), and on the other hand, a trapezoidal back growth platform design is adopted at the bottom of the narrow channels (which still has a high gripping force on the phase change material in a narrow space). Therefore, this narrow channel with a narrow opening and high gripping force can not only pass through the wafer to grow the phase change material on the back of the optical waveguide, but also reduce the adverse effects of the optical waveguide back window opening process on the finished wafer.

[0089] In some embodiments, a gap space is formed between an edge of the third outer surface and the first outer surface and / or the second outer surface, and the protective material of the protective layer is embedded in the gap space.

[0090] For example, in some embodiments, the protective layer 04 includes: a gap layer 041 embedded in the gap space, and a cover layer 042 covering the lower surface of the phase change material layer. The back growth platform 03, the phase change material layer 02 and the protective layer 04 are embedded and connected with each other to achieve stable formation of the phase change material on the back growth platform.

[0091] In this embodiment, an etching process is preferably used to form a backside growth platform with a rough surface in the second groove II.

[0092] In some embodiments, the second width X2 of the second slot II is equal to or similar to the first width X1 of the first slot.

[0093] In some embodiments, the angle α ranges from 85° to 90°.

[0094] In this embodiment, it is preferred to form only a back growth platform with a slight inclination angle on the optical waveguide, such as the angle α between the first guide portion and the second guide portion of the back growth platform is: 85°≤α<90°. This simplifies the etching process so that the set growth platform can be formed by only a small amount of etching residue, thereby improving the stability of the phase change material deposition.

[0095] In some embodiments, the first thickness is 1 nm-100 nm.

[0096] Preferably, in some embodiments, the protective layer 04 can at least partially fill the narrow and long channel, thereby protecting the phase change material on the one hand, and strengthening the structure of the wafer to a certain extent on the other hand, further alleviating the damage that may be caused by the back window opening process.

[0097] For example, in some embodiments, the protection layer 04 can completely cover the exposed outer surface of the phase-change material layer 02 .

[0098] Furthermore, in some embodiments, the protection layer 04 may preferably fill up the first groove.

[0099] Further, in some embodiments, see Figure 3 As shown, the protection layer 04 can further partially fill the second groove II on the basis of filling the first groove I.

[0100] Of course, in other embodiments, the protection layer 04 directly fills the narrow and long channel 10 .

[0101] In some embodiments, at least one metal layer is disposed in the first structure layer 07 , and the metal layer is disposed adjacent to the optical waveguide.

[0102] In some embodiments, at least one of the material layers is a Ge material layer.

[0103] In some embodiments, the material of the first structural layer 07 is one or more of the following: SiO 2 , Al 2 O 3 , and ITO.

[0104] In some embodiments, the material of the second structural layer 05 is one or more of the following: SiO2.

[0105] In some embodiments, the material of the protective layer may be one or more of the following: SiO2, Al2O3, ITO.

[0106] In some embodiments, the phase change material layer is made of a superlattice material; or, the phase change material layer is formed of a chalcogenide containing antimony or selenium, or the phase change material layer contains the chalcogenide, wherein the chalcogenide includes Sb2Se3 or SbSe, Sb2S3 or SbS, Ge2Sb2Se4Te; or, the phase change material of the phase change material layer includes a compound or alloy containing an element combination of germanium, antimony, selenium, and vanadium oxide, or a mixture of the compounds; the compounds include; NbOx, GeTe, GeSb, GaSb, AgInSbTe, InSb, InSbTe, InSe, SbTe, TeGeSbS, AgSbSe, SbSe, GeSbMnSn, AgSbTe, AuSbTe and AlSb.

[0107] In some embodiments, the thickness of the phase change material layer is 1 nm-1 μm.

[0108] Embodiment 2

[0109] The present invention also proposes a method for preparing an optical waveguide device corresponding to the modulation layer set on the back side. It is worth noting that in the front window opening process, in order to avoid damage to the optical waveguide during the processing, a stop layer and an oxide layer of a specified thickness are pre-set on the optical waveguide, and then the oxide layer and the stop layer are etched in sequence. However, the process of pre-forming the stop layer will inevitably cause certain damage to the Ge material layer, and especially when the material layers on the optical waveguide are relatively complex, this protection process will also easily cause damage to other material layers on the optical waveguide during the processing.

[0110] In this regard, the present invention provides a method for preparing an optical waveguide device (i.e., a back-side windowing process), wherein the method is used to prepare a narrow channel on an initial multilayer structure to grow a phase change material in the narrow channel; correspondingly, see Figure 7 As shown, the preparation method comprises the steps of:

[0111] S101, providing the initial multi-layer structure, wherein the initial multi-layer structure comprises: a first structural layer 07, a first recessed area is formed on a first surface of the first structural layer 07, an optical waveguide 01 is arranged in the first recessed area, and at least one material layer 08 is arranged on the front surface of the optical waveguide 01; a second structural layer 05 connected to the first surface of the first structural layer 07, and a substrate layer 06 connected to the second structural layer 05;

[0112] S102, thinning the substrate layer from the second thickness to a third thickness, and correspondingly forming a thinned layer;

[0113] For example, in some embodiments, the substrate layer (eg, Si substrate) may be thinned from an initial second thickness of 725 μm to a third thickness of 50 μm.

[0114] S103, preparing the narrow and long channel corresponding to the optical waveguide 01 on the current initial multilayer structure; wherein S103 includes:

[0115] S31, etching the thinned layer using a first etching method to form a narrow second groove II on the thinned layer, so that at least a portion of the second structural layer is exposed through the narrow second groove, correspondingly forming a first multi-layer structure;

[0116] S32, etching the second structural layer using a second etching method, so that a narrow and long first groove I is formed on the second structural layer, so as to form a second multilayer structure (such as Figure 2As shown), wherein the narrow first slot and the narrow second slot form the narrow channel, at this time, a first guide portion 031 is formed on the side wall of the narrow first slot, and a second guide portion 032 with a first thickness is formed on the back of the optical waveguide 01, wherein the first outer surface of the first guide portion is arranged in an inclined surface, so that an angle α is formed between the plane where the first outer surface is located and the second outer surface of the second guide portion, and the angle range of the angle α is 80°-90°; correspondingly, the first outer surface is connected to the second outer surface to form a back growth platform, so that the cross-section of the back growth platform is a trapezoidal structure;

[0117] S104, growing a phase change material layer on the back growth platform in the narrow and long channel by using a first growth method;

[0118] S105 , growing a protective layer on the phase change material layer using a second growth method to fill the narrow and long channel.

[0119] In this embodiment, a through etching method is adopted for the substrate layer (such as Si substrate), that is, a through second groove II is etched in the substrate layer, and then a non-through etching is performed on the second structural layer (such as SiO2 box) to form a back growth platform therein, thereby promoting the stable growth of the phase change material.

[0120] The backside growth process proposed in the present invention can directly utilize the wafer (such as the second structure layer and the substrate layer) for etching, and utilize the residues in the etching process to form a thinner backside growth platform. This can simplify the growth process (no need to pre-deposit a stop layer or an oxide layer), and on the other hand, since no pre-deposition step is required, it can reduce the consumption of consumables and reduce the adverse effects on the multi-layer materials on the front side of the optical waveguide during the processing.

[0121] In some embodiments, before S103, the step further includes:

[0122] S106, using at least two groups of different first etching conditions to etch at least two groups of the initial multilayer structures through a first etching method to form the second groove II on the substrate layer to obtain at least two groups of the first multilayer structures; wherein the first etching conditions include: a first raw material component, a first etching time.

[0123] For example, in some embodiments, when the etching method is dry etching, the raw material components are the type and components of the gas, and correspondingly, the raw material components include: a first gas with a first proportion, and a second gas with a second proportion.

[0124] For another example, in some embodiments, when the etching method is wet etching, the raw material is a solution, and correspondingly, the raw material components include: a solvent, and a solute with a specific concentration.

[0125] S107, collecting at least two groups of first etching results from at least two groups of the first multilayer structures, wherein the first etching results include: a second width X2 of the second groove, and a second depth H2 of the second groove.

[0126] S108, determining whether the first etching result meets a set first etching standard, and if so, recording the first etching result as a qualified result.

[0127] For example, in some embodiments, the first etching standard includes: a second standard width, and a second standard depth. Correspondingly, the step of judging whether the first etching result meets the set first etching standard includes: calculating the second width difference between the second width and the second standard width; calculating the second depth difference between the second depth and the second standard depth; when the second width difference is less than the set width threshold, and when the second depth difference is less than the set depth threshold, it is considered that the first etching result meets the set first etching standard.

[0128] S109, selecting the first etching condition corresponding to the qualified result as the first recommended condition.

[0129] In some embodiments, the first etching method may be dry etching, and correspondingly, the raw material components (or etching components) suitable for forming narrow and long channels on the substrate layer may be any one or more of the following: -SF6-based plasma: SF6 / O2 mixed gas, typical ratio 80:20; -Cl2-based plasma: Cl2 / BCl3, typical ratio 70:30; -HBr-based plasma: HBr / O2, typical ratio 90:10; -CF4-based plasma: CF4 / O2, the ratio can be adjusted between 80:20 and 90:10.

[0130] Alternatively, in some embodiments, the first etching method may be wet etching, and correspondingly, the raw material components suitable for forming the narrow and long channels on the substrate layer may be one or more of: - KOH aqueous solution: 20-45% concentration (the etching temperature is usually about 80-85°C), - TMAH: 25% concentration commonly used - HNA system (HF: HNO3: CH3COOH): the typical ratio can be 1:3:8; - EDP solution (ethylenediamine-pyridine-water).

[0131] It is worth noting that the present invention designs two major stages for the preparation of the narrow and long channel: 1) local etching of the narrow and long channel on the substrate layer; 2) etching the bottom area of ​​the narrow and long channel on the second structural layer 05. Specifically, for the first etching stage, the two key factors of etching raw materials and etching time are selected in this embodiment to control the etching speed, so as to form a narrow and long channel with a narrow opening in the upper layer area of ​​the wafer, and the deep etching of the narrow opening provides an initial etching environment for the subsequent second etching stage, so that the bottom morphology of the narrow and long channel can be further optimized on the basis of the second etching stage.

[0132] Furthermore, for the second etching stage, the present invention proposes a technical solution for optimizing and screening the bottom morphology (especially the first thickness and the angle α) of the narrow and long channel, which in some embodiments further includes the steps of:

[0133] S110, etching the second structural layer 05 on the first multilayer structure by the second etching method using at least two sets of different second etching conditions, so as to correspondingly form the narrow first groove I on the second structural layer and then form the second multilayer structure, wherein the narrow first groove and the narrow second groove are connected to form the narrow channel.

[0134] In this embodiment, different second etching conditions will form a backside growth platform with different specification parameters in the narrow and long channel, and the specifications include: a first thickness, and an angle α.

[0135] In some embodiments, the second etching condition includes: a second raw material component and a second etching time. Different second etching conditions have different raw material components or different etching times.

[0136] S111, collecting at least two groups of second etching results from at least two groups of the second multilayer structures, wherein the second etching results include: a first thickness L1, and an angle α;

[0137] In some embodiments, the first thickness may be an average thickness of each point on the second guide portion 032 .

[0138] S112, performing step S104 and step S105 on at least two groups of the second multilayer structures respectively, so as to prepare at least two groups of optical waveguide devices;

[0139] S113, performing an optical transmission test on at least two groups of the optical waveguide devices, and collecting corresponding test results, the test results including: actual transmission efficiency of the optical signal between the optical waveguide and the phase change material;

[0140] For example, in some embodiments, the test process is: inputting a first signal light into the optical waveguide, at least a portion of the first signal light (or referred to as the second signal light) can enter the phase change material, and be modulated into a third signal light through the phase change material, and the third signal light is input into the optical waveguide again to modulate the overall intensity of the signal light transmitted in the optical waveguide. Wherein, when the signal light is transmitted between the optical waveguide and the phase change material, a certain transmission loss may be generated, such as part of the signal light may not be able to penetrate the guide part into the phase change material, or be consumed due to refraction, etc., which will result in only part of the signal light being effectively modulated, and correspondingly, the transmission efficiency can be used to characterize the proportion of the signal that can be effectively modulated in the optical signal in the total optical signal (such as the first optical signal).

[0141] S114, judging whether the test result meets the preset transmission standard, if so, selecting the second etching result corresponding to the test result as the second recommended condition, that is, selecting a suitable bottom morphology for the narrow and long channel, namely the first thickness L1, and the angle α, two key parameters.

[0142] For example, in some embodiments, the transmission standard has a preset transmission standard efficiency. Correspondingly, determining whether the test result meets the preset transmission standard includes the steps of: calculating the efficiency difference between the actual transmission efficiency and the transmission efficiency; when the efficiency difference is less than the set efficiency threshold, the test result is considered to meet the preset transmission standard.

[0143] That is to say, in the present invention, for the first and second etching stages, two major dominant technical routes are designed in this embodiment respectively: 1) for the initial structure of the narrow and long channel (i.e., the second groove), the etching width and depth results are tested as the leading factor to efficiently screen out the suitable first etching conditions, thereby realizing the rapid preparation of the initial structure of the narrow and long channel; 2) for the modulation performance (or working stability) of the phase change material, the bottom morphology (such as the first thickness and the angle α) of the narrow and long channel is accurately optimized by focusing on the transmission efficiency as the leading factor in the test results.

[0144] It can be understood that, in this embodiment, preferably, the etching speed can be dominantly controlled to etch bottom morphologies of different specifications in the narrow channel, and the best bottom signal can be screened out by testing the light transmission efficiency.

[0145] Of course, in other embodiments, after screening the bottom morphology of the narrow channel, i.e., the first thickness and the angle α, engineers can use the specifications of the bottom morphology as a guide and combine professional experience to flexibly select different types of etching methods or etching raw materials for different application scenarios or different preparation requirements.

[0146] For example, different etching methods or etching materials have different adaptability in different scenarios (such as different structural layer types or different industrial environments). The present invention can also reversely screen different etching conditions again with the help of the preferred first thickness and angle.

[0147] In some embodiments, the second etching condition is dry etching, and correspondingly, the second raw material component can be any one or more of the following: -CHF3 / CF4 mixed gas, typical ratio 60:40, -C4F8 / O2, typical ratio 75:25, -CF4 / H2, typical ratio 85:15, -C2F6 / CHF3, can be mixed in a ratio of 70:30. Preferably, when dry etching is used, the above different raw material components can be used as different etching conditions to prepare narrow and long channels with different morphologies.

[0148] In some embodiments, the second etching condition is wet etching, and correspondingly, the second raw material component can be one or more of the following: - buffered oxide etchant (BOE): NH4F:HF typical ratio is 6:1 or 7:1, - hydrofluoric acid (HF) solution: the concentration is generally 1-10%, - HF:H2O mixed solution, the ratio can range from 1:10 to 1:100.

[0149] It is worth noting that, during the etching process, multiple process parameters such as etching gas flow, chamber pressure, RF power, temperature, etching time, solution concentration, etc. may have a certain impact on the etching results. In order to alleviate the damage that may be caused to the wafer by the back window opening process, and at the same time ensure that the narrow channel opened can more stably guide the growth of phase change materials, the present invention proposes a technical solution for selecting two key factors, etching raw materials and etching time, to control the etching speed to form a narrow channel on the wafer. Specifically, in the present invention, the etching raw materials and etching time are coordinated to form a narrow channel in a limited area on the wafer. On the one hand, the focus is on ensuring that a sufficiently deep etching can be completed, while controlling the reaction area of ​​the etching raw materials below the horizontal plane, thereby preparing a narrow channel with only a narrow opening on the back of the optical waveguide and capable of stably growing phase change materials.

[0150] Furthermore, in this embodiment, the modulation capability (specifically, the transfer efficiency) of the phase change material after the phase change material is grown on the narrow channel is used to evaluate the effectiveness of the narrow channel. In this regard, in order to improve the effectiveness of the narrow channel, the present invention selects two morphological data, such as the first thickness and the angle α of the back growth platform in the narrow channel (i.e., the bottom morphology of the narrow channel), to conduct a targeted evaluation of the depth and bottom morphology of the narrow channel.

[0151] Furthermore, the present invention can also use the specific bottom morphology of the narrow and long channel (that is, the first thickness and angle α of the back growth platform) as the process target, and use the etching raw materials and etching time as the dominant screening factors to quickly screen out the etching process suitable for the specific bottom morphology of the narrow and long channel (or, in other words, the second etching condition especially suitable for etching the bottom structure of the narrow and long channel).

[0152] From another perspective, for this new back windowing process, the present invention selects two key factors, namely, etching raw materials and etching time, to control the etching speed, thereby being able to critically guide the core morphology of the narrow and long channel. That is, by quickly setting the limited factors, the recommended conditions suitable for the back windowing process are efficiently selected.

[0153] In this embodiment, the first thickness and the angle are selected so that the phase change material grown on the back platform has better stability. In particular, the first thickness and the angle are limited to a certain extent, so that only a small amount of residue is formed during the etching process, and there is no need to expand the width of the groove. Under the premise of ensuring sufficient growth area, the impact of the etching process on the wafer is reduced, that is, the size of the groove etched on the wafer is reduced as much as possible.

[0154] Furthermore, in some embodiments, when the second recommended condition is screened out through the testing process, such as after setting the values ​​of the two key parameters of the first thickness L1 and the angle α, the preparation method may further include: a detection step of detecting the first thickness.

[0155] Specifically, in some embodiments, the step of detecting the first thickness may include:

[0156] Obtaining a measured value of a first thickness of the back growth platform; for example, in some embodiments, the cross-sectional structure of the second structural layer may be observed by a focused ion beam microscope (FIB) or a scanning electron microscope (SEM) to obtain the measured value of the first thickness;

[0157] The thickness difference between the measured value and the set value of the first thickness is determined. When the thickness difference is less than the set thickness difference threshold, it is considered that the second structural layer preliminarily meets the requirements of back window opening and can stably grow and carry phase change materials.

[0158] Understandably, Figure 4 The back growth platform shown is only a preferred embodiment of the present invention. With the change of etching method, the width of the back growth platform can also be designed to gradually decrease in the direction away from the optical waveguide.

[0159] It is understandable that the preparation method proposed in the present invention can be applied to the preparation of the semiconductor device in any of the above embodiments, and will not be described in detail here.

[0160] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0161] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, a magnetic disk, or an optical disk), and includes a number of instructions for a computer terminal (which can be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present invention.

[0162] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. An optical waveguide device, characterized in that: include: A first structural layer (07), wherein a first recessed area is formed on a first surface of the first structural layer (07), an optical waveguide (01) is arranged in the first recessed area, and at least one material layer (08) is arranged on the front surface of the optical waveguide (01); a second structural layer (05) connected to the first surface of the first structural layer (07), and a substrate layer (06) connected to the second structural layer (05); wherein the second structural layer (05) and the substrate layer (06) are provided with a first slot (I) and a second slot (II) corresponding to the optical waveguide (01) in sequence, and the first slot and the second slot form a narrow and long channel, and the depth of the narrow and long channel is greater than the width; a first guide portion (031) is formed on the side wall of the first slot, and a second guide portion (032) having a first thickness is formed on the back side of the optical waveguide (01), wherein the first outer surface of the first guide portion is arranged in an inclined plane, so that an angle α is formed between the plane where the first outer surface is located and the second outer surface of the second guide portion, and the angle range of the angle α is 80°-90°; correspondingly, the first outer surface is connected to the second outer surface to form a back growth platform, and the cross-section of the back growth platform is a trapezoidal structure; A phase change material layer (02) is provided on the back growth platform, and a protective layer (04) is also formed on the third outer surface of the phase change material layer (02).

2. An optical waveguide device according to claim 1, characterized in that: A gap space is formed between the edge of the third outer surface and the first outer surface and / or the second outer surface, and the protective material of the protective layer is embedded in the gap space.

3. An optical waveguide device according to claim 1, characterized in that: The angle α is in the range of 85°-90°; and / or the width of the back growth platform is less than or equal to the width of the optical waveguide (01).

4. An optical waveguide device according to claim 1, characterized in that: The distribution density of the opening area of ​​the narrow and long channels in the substrate layer is less than or equal to 0.03%; wherein the distribution density=opening area×number of narrow and long channels / surface area of ​​the substrate layer.

5. The optical waveguide device according to claim 1, characterized in that: The first thickness is 1 nm-200 nm.

6. The optical waveguide device according to claim 1, characterized in that: At least one metal layer is arranged in the first structural layer (07), and the metal layer is arranged adjacent to the optical waveguide; And / or, at least one of the material layers is a Ge material layer.

7. A method for preparing an optical waveguide device, characterized in that: The preparation method is used to prepare a narrow and long channel on an initial multilayer structure to grow a phase change material in the narrow and long channel; correspondingly, the preparation method comprises the steps of: S101, providing the initial multi-layer structure, wherein the initial multi-layer structure comprises: a first structural layer (07), a first recessed area formed on a first surface of the first structural layer (07), an optical waveguide (01) disposed in the first recessed area, and at least one material layer (08) disposed on the front surface of the optical waveguide (01); a second structural layer (05) connected to the first surface of the first structural layer (07), and a substrate layer (06) connected to the second structural layer (05); S102, thinning the substrate layer from the second thickness to a third thickness, and correspondingly forming a thinned layer; S103, preparing the narrow and long channel corresponding to the optical waveguide (01) on the current initial multilayer structure; wherein S103 comprises: S31, etching the thinned layer using a first etching method to form a second narrow groove (II) on the thinned layer, so that at least a portion of the second structural layer is exposed through the second narrow groove, thereby correspondingly forming a first multi-layer structure; S32, etching the second structural layer using a second etching method, so that a first narrow groove (I) is formed on the second structural layer to form a second multilayer structure, wherein the first narrow groove and the second narrow groove form the narrow channel, at this time, a first guide part (031) is formed on the side wall of the first narrow groove, and a second guide part (032) with a first thickness is formed on the back of the optical waveguide (01), wherein the first outer surface of the first guide part is arranged in an inclined surface, so that an angle α is formed between the plane where the first outer surface is located and the second outer surface of the second guide part, and the angle range of the angle α is 80°-90°; correspondingly, the first outer surface is connected to the second outer surface to form a back growth platform, so that the cross-section of the back growth platform is a trapezoidal structure; S104, growing a phase change material layer on the back growth platform in the narrow and long channel by using a first growth method; S105 , growing a protective layer on the phase change material layer using a second growth method to fill the narrow and long channel.

8. The preparation method according to claim 7, characterized in that: Before S103, the step further includes: S106, etching at least two groups of the initial multilayer structures by a first etching method using at least two groups of different first etching conditions to form the narrow and long second grooves (II) on the substrate layer, thereby obtaining at least two groups of the first multilayer structures; wherein the first etching conditions include: a first raw material component and a first etching time; S107, collecting at least two groups of first etching results from at least two groups of the first multilayer structures, wherein the first etching results include: a second width X2 of the second groove, and a second depth H2 of the second groove; S108, determining whether the first etching result meets a set first etching standard, and if so, recording the first etching result as a qualified result; S109, selecting the first etching condition corresponding to the qualified result as the first recommended condition.

9. The preparation method according to claim 7 or 8, characterized in that: Also includes the steps: S110, etching the second structural layer (05) on the first multilayer structure by the second etching method using at least two sets of different second etching conditions, so as to correspondingly form the first narrow groove (I) on the second structural layer to form the second multilayer structure, wherein the first narrow groove and the second narrow groove are connected to form the narrow channel; S111, collecting at least two groups of second etching results from at least two groups of the second multilayer structures, wherein the second etching results include: a first thickness, and an angle α; S112, performing step S104 and step S105 on at least two groups of the second multilayer structures respectively, so as to prepare at least two groups of optical waveguide devices; S113, performing an optical transmission test on at least two groups of the optical waveguide devices, and collecting corresponding test results, the test results including: transmission efficiency of the optical signal between the optical waveguide and the phase change material; S114, determining whether the test result meets a preset transmission standard, and if so, selecting the second etching result corresponding to the test result as a second recommended condition.

10. The preparation method according to claim 9, characterized in that: The second etching method is dry etching or wet etching.

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