SOI substrate structure with waveguide buried layer and preparation method and application thereof

Abstract

The invention discloses an SOI substrate structure with a waveguide buried layer and a preparation method and application of the SOI substrate structure. The SOI substrate structure comprises a substrate silicon layer, a buried oxide layer and a top silicon layer which are sequentially stacked, wherein a waveguide is arranged in the buried oxide layer, and the buried oxide layer forms a cladding of the waveguide as a core layer. According to the invention, the silicon nitride waveguide with excellent performance and the active device on the SOI can be integrated on the same platform of the SOI substrate structure with the waveguide buried layer, so that the advantages of the silicon nitride waveguide and the active device can be fully utilized, the excellent performance is shown, and the silicon nitride waveguide and the active device have the advantages of simple process, compatibility with a standard CMOS (Complementary Metal-Oxide-Semiconductor Transistor) process and low manufacturing cost.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor integrated circuit manufacturing process, and in particular to an SOI substrate structure with a waveguide buried layer, a preparation method and application thereof. Background Art

[0002] Photonic integration is a hot topic in today's scientific and technological community, and improving integration is of utmost importance. Optical waveguides are the foundation and core of photonic integration. Their main function is to confine light in a specific medium and guide light waves to propagate in a certain direction. The current mainstream optical waveguide material is SOI (Silicon-on-insulator). The refractive index difference between the Si material in the core layer of the optical waveguide and the SiO2 material in the cladding is large, and the light confinement effect is strong. Submicron optical waveguides can be prepared, greatly improving integration. As optical interconnect technology develops towards ultra-high speed and dense integration, materials such as SOI have shown an important position in photonic integration. However, due to the problem of large optical loss in SOI optical waveguide materials, it has an adverse effect on integration.

[0003] Silicon nitride is the most promising next-generation optical waveguide material. It has many advantages in optical waveguide devices:

[0004] (1) High material strength and stable structure;

[0005] (2) The bandgap is large and the transparent band is wide, and its transparent window can extend from infrared to visible light band;

[0006] (3) Compatible with standard CMOS process and low manufacturing cost;

[0007] (4) High refractive index. The refractive index difference with SiO2 is large at a wavelength of 1550nm. The waveguide size and bending radius can be very small, the integration is high, and 3D large-scale integration can be achieved.

[0008] (5) The loss is very small, 3 to 4 orders of magnitude lower than that of SOI waveguide, making it a very good waveguide material.

[0009] However, silicon nitride also has many shortcomings as a photoelectric material. For example, growing silicon nitride on Si will produce large stress; silicon nitride is an insulating material, is non-conductive, has a weak photoelectric effect, and is difficult to make active devices.

[0010] If the high-performance silicon nitride waveguide devices can be integrated with active devices on SOI such as modulators, detectors and lasers on the same platform to fully utilize their respective advantages and show many excellent performances, it will be an important direction for photonic integration. Summary of the invention

[0011] The purpose of the present invention is to overcome the above-mentioned defects in the prior art and to provide an SOI substrate structure with a waveguide buried layer and a preparation method and application thereof.

[0012] To achieve the above object, the technical solution of the present invention is as follows:

[0013] The present invention provides an SOI substrate structure with a waveguide buried layer, comprising:

[0014] A substrate silicon layer, a buried oxide layer and a top silicon layer stacked in sequence;

[0015] Wherein, a waveguide is provided in the buried oxide layer, and the buried oxide layer forms a cladding of the waveguide.

[0016] Furthermore, the top silicon layer is used to form an active device, and the waveguide directly coupled to the active device is at a certain distance from the top silicon layer, and the distance satisfies the condition for the waveguide to achieve interlayer evanescent wave coupling.

[0017] Furthermore, the waveguide and the buried oxide layer together form a dielectric layer buried layer of an SOI substrate structure having a waveguide buried layer.

[0018] Furthermore, the waveguide material includes silicon nitride.

[0019] Furthermore, one or more waveguides are provided in the buried oxide layer; wherein, when there are multiple waveguides, each waveguide is provided in the same layer of the buried oxide layer, or is provided in different layers of the buried oxide layer, and the distance between any two waveguides located in adjacent layers and used for direct coupling satisfies the conditions for realizing interlayer evanescent wave coupling.

[0020] The present invention also provides a method for preparing a SOI substrate structure with a waveguide buried layer, comprising:

[0021] providing a first silicon substrate and a second silicon substrate;

[0022] forming a first oxide layer on the surface of the first silicon substrate, and forming a second oxide layer on the surface of the second silicon substrate;

[0023] forming a waveguide in the first oxide layer;

[0024] Bonding the second oxide layer surface of the second silicon substrate to the first oxide layer surface of the first silicon substrate, so that the second silicon substrate and the first silicon substrate are stacked as a whole;

[0025] The second silicon substrate is thinned to form an SOI substrate structure with a waveguide buried layer, which has the first silicon substrate as a substrate silicon layer, the first oxide layer and the second oxide layer bonded to each other as a buried oxide layer, and the thinned second silicon substrate as a top silicon layer.

[0026] Furthermore, one to multiple layers of the waveguide structure are formed in the one to multiple layers of the first oxide layer and filled with waveguide material, so as to form one to multiple layers of the waveguide in the one to multiple layers of the first oxide layer; wherein the waveguide and the buried oxide layer together form a buried dielectric layer of the SOI substrate structure having a buried waveguide layer.

[0027] Furthermore, the surface of at least one of the waveguides is exposed from the surface of the outermost layer of the one to multiple first oxide layers and is flush with each other, or all of the waveguides are covered by the outermost layer of the one to multiple first oxide layers; wherein the top silicon layer is used to form an active device, and the distance between the waveguide directly coupled to the active device and the top silicon layer satisfies the condition for the waveguide to achieve interlayer evanescent wave coupling, and the distance between any two waveguides located in adjacent layers and used for direct coupling satisfies the condition for achieving interlayer evanescent wave coupling.

[0028] The present invention also provides an application of the above-mentioned SOI substrate structure with a buried waveguide layer in the field of photon integration.

[0029] Furthermore, the application includes integrating optoelectronic active devices on the top silicon layer of the SOI substrate structure with the buried waveguide layer.

[0030] It can be seen from the above technical scheme that the present invention uses a first silicon substrate with a first oxide layer and a second silicon substrate with a second oxide layer to first form a waveguide in the first oxide layer, and then the second oxide layer is bonded to the first oxide layer at the surface, so that the second silicon substrate and the first silicon substrate are stacked as a whole, forming a SOI substrate structure with a waveguide buried layer having a substrate silicon layer (first silicon substrate), a buried oxide layer (first oxide layer and second oxide layer) and a top silicon layer (second silicon substrate) stacked in sequence, and can utilize the advantages of, for example, low loss of silicon nitride waveguides and better production of active devices in SOI to achieve improved integration of photonic devices. At the same time, the distance between the waveguide formed in the buried oxide layer and the top silicon layer can be accurately controlled within the range of the evanescent wave field transmission depth, so when an active device is formed in the top silicon layer, interlayer evanescent wave coupling can be achieved between the waveguide and the corresponding active device and between the corresponding waveguides, and alignment is relatively simple. Moreover, by first forming a waveguide with a large thermal budget and then forming an active device on a SOI substrate structure with a buried waveguide layer, the thermal budget requirement can be fully met; by forming a waveguide by trench filling, the problem of excessive stress caused by the previous deposition of silicon nitride can be alleviated. The present invention can integrate the silicon nitride waveguide with excellent performance with the active device on SOI on the same platform of the SOI substrate structure with a buried waveguide layer, thereby making full use of their respective advantages and showing excellent performance. The present invention has the advantages of simple process, compatibility with standard CMOS process, and low production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of an SOI substrate structure with a waveguide buried layer according to a preferred embodiment of the present invention;

[0032] Figure 2-Figure 9 A process flow chart of a method for preparing a SOI substrate structure with a buried waveguide layer according to a preferred embodiment of the present invention;

[0033] Fig.10 A schematic diagram of a preferred embodiment of the present invention showing an SOI substrate structure with a buried silicon nitride waveguide layer applied to an integrated optoelectronic active device;

[0034] Figure 11-Figure 12 A schematic diagram of a silicon nitride waveguide integrated structure of a comparative embodiment. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0036] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0037] refer to Figure 1 The SOI substrate structure with a buried waveguide layer of the present invention comprises a substrate silicon layer 10 (Si substrate), a buried oxide layer 11 (SiO2) and a top silicon layer 12 (SOI) stacked in sequence from bottom to top. A waveguide 20 is arranged in the buried oxide layer 11, and the buried oxide layer 11 forms a cladding of the waveguide 20 as a core layer.

[0038] In some embodiments, one or more waveguides 20 may be disposed in the buried oxide layer 11 .

[0039] In some embodiments, a waveguide 20 may be provided in the buried oxide layer 11 (see Fig.10 ).

[0040] In some embodiments, a multi-layer waveguide 20 may be disposed in the buried oxide layer 11 .

[0041] Furthermore, the number of waveguides 20 in each layer may be one or more. Figure 1 The structure of the SOI substrate with a buried waveguide layer is exemplarily shown when two layers of waveguides 20 are provided in the buried oxide layer 11 , and each layer has a plurality of waveguides 20 .

[0042] In some embodiments, the waveguide 20 may include strip waveguides 21, 26, 28 having different sizes, and / or, the waveguide 20 may include ridge waveguides 22, 27 having different sizes, and / or, the waveguide 20 may include parallel waveguides (double-layer waveguides) 23, 24, 25 having different sizes.

[0043] The top silicon layer 12 can be used to prepare active devices (refer to Fig.10). The waveguide 20 used for direct coupling with the active device is arranged at a position aligned with the formation position of the corresponding active device and is at a certain distance from the top silicon layer 12. Since the distance is small (within the range of the evanescent wave field transmission depth (i.e., the evanescent length (the thickness at which the wave field decays to the boundary value 1 / e))), the distance is sufficient to satisfy the condition for achieving interlayer evanescent wave coupling between the waveguide 20 and the active device arranged in the top silicon layer 12. Moreover, the distance between any two waveguides 20 located in adjacent layers and used for direct coupling can also satisfy the condition for achieving interlayer evanescent wave coupling.

[0044] In the SOI substrate structure with a buried waveguide layer of the present invention, the substrate silicon layer 10 is used as a silicon substrate; the buried oxide layer 11 of the waveguide 20 with SiO2 as a cladding is integrated, and together with the waveguide 20, forms a buried dielectric layer in the SOI substrate structure with a buried waveguide layer.

[0045] In some embodiments, the waveguide 20 material includes a dielectric material. For example, the waveguide 20 material includes silicon nitride (SiN). That is, the SiO2 buried oxide layer 11 is a dielectric layer that integrates the silicon nitride waveguide 20 device. The silicon nitride waveguide 20 is located in the dielectric layer of the SOI substrate structure with the waveguide buried layer, that is, the SOI substrate structure containing the silicon nitride waveguide buried layer is formed.

[0046] Through the three-layer structure of the SOI substrate structure with the waveguide buried layer, the advantages of, for example, low silicon nitride waveguide loss and better SOI for making active devices are utilized, thereby achieving an improvement in the integration of photonic devices.

[0047] In the SOI substrate structure with a buried waveguide layer of the present invention, since the waveguide 20 structure is manufactured before the active device, the structure, position and direction of the waveguide 20 need to be designed in advance to facilitate mutual alignment between layers when the active device is subsequently manufactured. At this time, the relatively large size of the waveguide 20 structure can make the alignment relatively simple.

[0048] The following is a further detailed description of a method for preparing a SOI substrate structure with a buried waveguide layer according to the present invention through specific implementations and in conjunction with the accompanying drawings.

[0049] refer to Figure 2-Figure 9 The method for preparing a SOI substrate structure with a buried waveguide layer of the present invention can be used to prepare the above-mentioned SOI substrate structure with a buried waveguide layer, and may include the following steps:

[0050] Step S1: providing a first silicon substrate 101 and a second silicon substrate 102 .

[0051] like Figure 2 As shown, a silicon substrate can be used as the first silicon substrate 101.

[0052] like Figure 3 As shown, another silicon substrate may be used as the second silicon substrate 102 .

[0053] Step S2 : forming a first oxide layer 111 on the surface of the first silicon substrate 101 , and forming a second oxide layer 112 on the surface of the second silicon substrate 102 .

[0054] like Figure 2-Figure 3 As shown, a deposition or oxidation process may be used to form a SiO 2 first oxide layer 111 on the surface of the first silicon substrate 101 and a SiO 2 second oxide layer 112 on the surface of the second silicon substrate 102 .

[0055] Step S3 : forming a waveguide 20 in the first oxide layer 111 .

[0056] like Figure 4 As shown, taking the formation of a layer of silicon nitride waveguide in the first oxide layer 111 as an example, a waveguide structure groove 201 of a prefabricated shape and size can be formed on the surface of the first oxide layer 111 by using photolithography and etching processes.

[0057] like Figure 5 As shown, a deposition process may be used to form a silicon nitride waveguide material layer 202 on the surface of the first oxide layer 111 , to fully fill the waveguide structure groove 201 , and to form a silicon nitride covering layer of a certain thickness on the surface of the first oxide layer 111 .

[0058] like Figure 6 As shown, a chemical mechanical polishing process may be used to remove the excess silicon nitride waveguide material layer 202 on the surface of the first oxide layer 111 outside the waveguide structure groove 201 , and form a silicon nitride waveguide 20 in the waveguide structure groove 201 .

[0059] If a multilayer waveguide 20 is required, the above steps can be repeated. Figure 2 , Figure 4-Figure 6The process shown is to continue to form a new second first oxide layer 111 on the surface of the first first oxide layer 111 of the structure formed above, form a second waveguide structure groove 201 of a prefabricated shape and size on the surface of the second first oxide layer 111, form a silicon nitride waveguide material layer 202 on the surface of the second first oxide layer 111 for the second time, fully fill the second waveguide structure groove 201, remove the excess silicon nitride waveguide material layer 202, and form a second silicon nitride waveguide 20 in the second waveguide structure groove 201. By analogy, more layers of silicon nitride waveguides 20 can be further formed, and the surfaces of all the formed waveguides 20 for direct coupling with active devices are exposed from the surface of the outermost layer (uppermost layer) of one to multiple layers of first oxide layers 111 and are flush with each other (the waveguide 20 here includes a single-layer waveguide 20, or a waveguide 20 whose surface is exposed on the surface of the uppermost first oxide layer 111 in a multi-layer waveguide 20). At the same time, by controlling the thickness of each first oxide layer 111, the distance between any two waveguides 20 located in adjacent layers and used for direct coupling can meet the conditions for achieving inter-layer evanescent wave coupling.

[0060] By forming a plurality of waveguide structure grooves 201 with different widths and depths in one or more first oxide layers 111, a plurality of strip waveguides 20 with different widths and depths can be formed in one or more first oxide layers 111 after filling (see Figure 1 By combining the waveguide structure grooves 201 located in different layers and having different widths (and depths) in a vertically connected manner, ridge waveguides 20 with different size portions can be formed in the plurality of first oxide layers 111 after filling (refer to Figure 1 By combining two adjacent waveguide structure grooves 201 located in the same layer or different layers in a parallel manner, a parallel waveguide (double-layer waveguide) 20 (reference) can be formed in one or more first oxide layers 111 after filling. Figure 1 Parallel waveguides 23, 24, 25).

[0061] The present invention adopts a trench filling method to form the silicon nitride waveguide 20, which can alleviate the problem of excessive stress caused by the previous method of first depositing silicon nitride and then patterning the waveguide.

[0062] Step S4: bonding the surface of the second oxide layer 112 of the second silicon substrate 102 to the surface of the first oxide layer 111 of the first silicon substrate 101, so that the second silicon substrate 102 and the first silicon substrate 101 are stacked as a whole.

[0063] like Figure 7-Figure 8As shown, the surface of the second oxide layer 112 on the second silicon substrate 102 can be oriented toward the surface of the first oxide layer 111 on the first silicon substrate 101 and aligned. Then, a bonding process can be used to bond the surface of the second oxide layer 112 to the surface of the first oxide layer 111 and the exposed surface of the silicon nitride waveguide 20, so that the second silicon substrate 102 and the first silicon substrate 101 are stacked as a whole through bonding.

[0064] It can be seen that after bonding, the second oxide layer 112 simultaneously becomes the upper cladding of the waveguide 20 exposed on the surface of the first oxide layer 111 (the waveguide 20 here includes a single-layer waveguide 20, or a waveguide 20 in a multi-layer waveguide 20 whose surface is exposed on the surface of the topmost first oxide layer 111).

[0065] It is worth noting that, according to specific process requirements, another first oxide layer 111 may be first formed on the surface of the first oxide layer 111 located at the top layer, and the surface of the waveguide 20 exposed on the surface of the top first oxide layer 111 may be covered (even if all the waveguides 20 formed are covered by the outermost layer of one to multiple first oxide layers 111), and an upper cladding layer of the waveguide 20 exposed on the surface of the top first oxide layer 111 may be formed, and then bonding with the second oxide layer 112 may be performed, and the present invention is not restricted to this.

[0066] Step S5: thinning the second silicon substrate 102 to form an SOI substrate structure with a waveguide buried layer, which has the first silicon substrate 101 as the substrate silicon layer 10, the bonded first oxide layer 111 and the second oxide layer 112 as the buried oxide layer 11, and the thinned second silicon substrate 102 as the top silicon layer 12.

[0067] like Fig. 9 As shown, the back side of the second silicon substrate 102 can be thinned by back side etching or smart stripping (Smart Cut) or the like until the thickness meets the process requirements for manufacturing active devices.

[0068] Thus, an SOI substrate structure with a silicon nitride waveguide buried layer is formed, which has a first silicon substrate 101 as a substrate silicon layer 10, a bonded first oxide layer 111 and a second oxide layer 112 as a buried oxide layer 11, and a thinned second silicon substrate 102 as a top silicon layer 12.

[0069] The waveguide 20 and the buried oxide layer 11 together form a dielectric layer buried layer of the SOI substrate structure with a waveguide buried layer.

[0070] Through the above steps, the distance between the waveguide 20 formed in the buried oxide layer 11 and the top silicon layer 12 can be precisely controlled, so that the distance between the waveguide 20 and the top silicon layer 12 is within the evanescent wave field transmission depth range (based on this, it is necessary to control the thickness of the second oxide layer 112, that is, the second oxide layer 112 is in the form of a thin oxide layer with a thickness less than that of the first oxide layer 111). Therefore, when an optoelectronic active device is formed in the top silicon layer 12, interlayer evanescent wave coupling can be achieved between the waveguide 20 and the corresponding active device. And through the above steps, the alignment between the later-made active device and the first-made corresponding waveguide 20 can be made relatively simple.

[0071] The application of the SOI substrate structure with a buried waveguide layer in the field of photonic integration includes integrating optoelectronic active devices (such as modulators, detectors, and lasers, etc.) on the top silicon layer 12 of the SOI substrate structure with a buried waveguide layer.

[0072] refer to Fig.10 . Photoelectric active devices such as detectors and modulators can be integrated in the top silicon layer 12 of the SOI substrate structure with a buried waveguide layer of the present invention. The detectors and modulators can be made by forming P-type and N-type doped regions in the top silicon layer 12, and a germanium (Ge) intrinsic layer as a light absorption region is further formed on the P-type and N-type doped regions of the detectors. A coupling structure is formed between the detectors and modulators and the corresponding silicon nitride waveguide 20 in the buried oxide layer 11 below, so that interlayer evanescent wave coupling is achieved between the waveguide 20 and the corresponding active device.

[0073] Therefore, when active devices are manufactured on the above-mentioned SOI substrate structure with a waveguide buried layer of the present invention, the respective advantages of SOI and silicon nitride in active and passive waveguide devices are utilized and the two are organically combined together.

[0074] Fig.11 It shows a waveguide integrated structure in which active devices (P-type and N-type doped regions of detectors and modulators) are first made in the SOI layer, and then a silicon nitride waveguide layer is made in the upper dielectric layer. The disadvantage is that when the silicon nitride layer is deposited to make the waveguide, a large thermal budget is inevitably brought about, and active devices often require doping, Ge epitaxy and other processes, which require a lower thermal budget to prevent failure problems caused by their re-diffusion, and it is more difficult to realize evanescent wave coupling and other structures that require close device spacing.

[0075] Fig.12A waveguide integration structure is shown in which active devices (P-type and N-type doped regions of detectors and modulators) and silicon nitride waveguides are manufactured on the same layer (SOI layer). The disadvantage is that since active and passive devices are integrated in the same plane, the process is more complicated and has more sophisticated process requirements. In addition, the large stress introduced when manufacturing silicon nitride waveguides by deposition and patterning may affect the integration of active devices.

[0076] Therefore, with Figure 11-Figure 12 Compared with the waveguide integrated structure of the comparative embodiment, the present invention utilizes a first silicon substrate 101 having a first oxide layer 111 and a second silicon substrate 102 having a second oxide layer 112, first forms a waveguide 20 in the first oxide layer 111, and then bonds the second oxide layer 112 to the first oxide layer 111 on the surface, so that the second silicon substrate 102 and the first silicon substrate 101 are stacked as a whole, forming an SOI substrate structure with a waveguide buried layer having a substrate silicon layer 10 (first silicon substrate 101), a buried oxide layer 11 (first oxide layer 111 and second oxide layer 112) and a top silicon layer 12 (second silicon substrate 102) stacked in sequence, and can utilize the advantages of, for example, low loss of silicon nitride waveguide 20 and better preparation of active devices of SOI to achieve improved integration of photonic devices. At the same time, the distance between the waveguide 20 formed in the buried oxide layer 11 and the top silicon layer 12 can be precisely controlled within the range of the evanescent wave field transmission depth, so when an active device is formed in the top silicon layer 12 (refer to Fig.10 ), interlayer evanescent wave coupling can be achieved between the waveguide 20 and the corresponding active device and between the corresponding waveguides, and alignment is relatively simple. Moreover, by first forming the waveguide 20 with a large thermal budget, when the active device is formed on the SOI substrate structure with a waveguide buried layer, the thermal budget requirement can be fully met; by forming the waveguide 20 by trench filling, the problem of excessive stress caused by the previous method of depositing silicon nitride can be alleviated.

[0077] In summary, the present invention can integrate the excellent performance silicon nitride waveguide 20 and the active device on SOI on the same platform of the SOI substrate structure with the waveguide buried layer, so as to make full use of their respective advantages and show excellent performance. The present invention has the advantages of simple process, compatibility with standard CMOS process, low manufacturing cost, and is suitable for promotion.

[0078] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A SOI substrate structure with a waveguide buried layer, characterized in that: include: A substrate silicon layer, a buried oxide layer and a top silicon layer stacked in sequence; Wherein, a waveguide is provided in the buried oxide layer, and the buried oxide layer forms a cladding of the waveguide.

2. The SOI substrate structure with a buried waveguide layer according to claim 1, characterized in that: The top silicon layer is used to form an active device, and the waveguide directly coupled to the active device is at a certain distance from the top silicon layer, and the distance satisfies the condition for the waveguide to achieve interlayer evanescent wave coupling.

3. The SOI substrate structure with a buried waveguide layer according to claim 1, characterized in that: The waveguide and the buried oxide layer together form a dielectric layer buried layer of an SOI substrate structure having a waveguide buried layer.

4. The SOI substrate structure with a waveguide buried layer according to claim 1, characterized in that: The waveguide material includes silicon nitride.

5. The SOI substrate structure with a waveguide buried layer according to claim 1, characterized in that: One or more waveguides are provided in the buried oxide layer; wherein, when there are multiple waveguides, each waveguide is provided in the same layer of the buried oxide layer, or is provided in different layers of the buried oxide layer, and the distance between any two waveguides located in adjacent layers and used for direct coupling satisfies the conditions for realizing interlayer evanescent wave coupling.

6. A method for preparing a SOI substrate structure with a buried waveguide layer, characterized in that: include: providing a first silicon substrate and a second silicon substrate; forming a first oxide layer on the surface of the first silicon substrate, and forming a second oxide layer on the surface of the second silicon substrate; forming a waveguide in the first oxide layer; Bonding the second oxide layer surface of the second silicon substrate to the first oxide layer surface of the first silicon substrate, so that the second silicon substrate and the first silicon substrate are stacked as a whole; The second silicon substrate is thinned to form an SOI substrate structure with a waveguide buried layer, which has the first silicon substrate as a substrate silicon layer, the first oxide layer and the second oxide layer bonded to each other as a buried oxide layer, and the thinned second silicon substrate as a top silicon layer.

7. The method for preparing a SOI substrate structure with a buried waveguide layer according to claim 6, characterized in that: By forming one or more layers of first oxide layers on the surface of the first silicon substrate, forming one or more layers of waveguide structure grooves in the one or more layers of first oxide layers and filling them with waveguide materials, one or more layers of the waveguide are formed in the one or more layers of first oxide layers; wherein the waveguide and the buried oxide layer together form a dielectric layer buried layer of an SOI substrate structure with a waveguide buried layer.

8. The method for preparing a SOI substrate structure with a buried waveguide layer according to claim 7, characterized in that: The surface of at least one of the waveguides is exposed from the surface of the outermost layer of the one to multiple layers of first oxide layers and is flush with each other, or all of the waveguides are covered by the outermost layer of the one to multiple layers of first oxide layers; wherein the top silicon layer is used to form an active device, the distance between the waveguide directly coupled to the active device and the top silicon layer satisfies the condition for the waveguide to achieve interlayer evanescent wave coupling, and the distance between any two waveguides located in adjacent layers and used for direct coupling satisfies the condition for achieving interlayer evanescent wave coupling.

9. Application of the SOI substrate structure with a buried waveguide layer according to any one of claims 1 to 5 in the field of photonic integration.

10. The use according to claim 9, characterized in that: The application includes integrating optoelectronic active devices on the top silicon layer of the SOI substrate structure with the buried waveguide layer.

Images