Modulator and method of forming
By designing second trenches of different lengths or germanium-silicon layer contents in the modulator structure, the problems of poor absorption contrast and heat loss during modulator integration are solved, achieving higher absorption contrast and reduced heat damage.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2026-06-30
AI Technical Summary
In the prior art, when multiple modulators with different operating wavelengths are integrated together, the absorption contrast between the modulators is poor, and applying different bias voltages will lead to heat loss and changes in the light absorption coefficient of the modulator.
In the modulator structure, the modulator structure is formed in the first trench and the second trench is formed on both sides of it, so that the modulator structure is suspended on the second trench. The length of the second trench or the germanium content in the germanium-silicon layer are different, resulting in different tensile stresses, thereby obtaining absorption edges with different operating wavelengths.
It improves the absorption contrast between modulators, reduces heat damage, and avoids changes in dark current and absorption coefficient due to changes in bias voltage.
Smart Images
Figure CN122307949A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of modulators, and more particularly to a modulator and a method for forming it. Background Technology
[0002] Large-scale silicon-based optoelectronic integrated optical circuits (such as optical phased arrays, photonic neural networks, multi-beam networks, etc.) require smaller modulator structures. To achieve wider optical band coverage and higher optoelectronic data processing capabilities, it is necessary to integrate modulators with multiple operating wavelengths. Integrating modulators with multiple operating wavelengths together is low-cost, simple to lay out, and easy to achieve electronic and photonic circuit integration.
[0003] In the prior art, after multiple modulators with different operating wavelengths are integrated on a chip, absorption edges with different operating wavelengths are obtained by applying different bias voltages to the modulators with different operating wavelengths.
[0004] However, applying different bias voltages to modulators operating at multiple wavelengths alters both the dark current generated by the modulator and its absorption coefficient, resulting in varying insertion losses and extinction ratios. This leads to very poor absorption contrast among the modulators. Furthermore, the bias voltage has a limited range for wavelength control, and the heat generated by different bias voltages is detrimental to integrated circuits. Summary of the Invention
[0005] The purpose of this invention is to provide a modulator array and a method for forming it, which can improve the absorption contrast between modulators and reduce heat damage.
[0006] To achieve the above objectives, the present invention provides a method for forming a modulator, comprising:
[0007] A substrate is provided, and a dielectric layer is formed on the surface of the substrate;
[0008] A plurality of first trenches extending along a first direction and spaced apart along a second direction are formed in the dielectric layer and the substrate, wherein the first direction and the second direction are perpendicular to each other;
[0009] A modulator structure is formed in the first trench. The modulator structure includes stacked N++ germanium-silicon layers, N+ germanium-silicon layers, quantum wells, P+ germanium-silicon layers, and P++ germanium-silicon layers. The quantum well includes at least three combinations of stacked germanium material layers and germanium-silicon material layers. In each combination, the germanium-silicon material layer is located on the surface of the germanium material layer.
[0010] A second trench is formed in the dielectric layer and substrate on both sides of each of the first trenches along the second direction, and the modulator structure is suspended on the second trenches. The lengths of each of the second trenches are different in the first direction.
[0011] Optionally, in the method of forming the modulator, the length of each of the second trenches increases sequentially along the second direction in the first direction.
[0012] Optionally, in the method of forming the modulator, the length of each of the second trenches in the extension direction of the first trench increases sequentially in an arithmetic sequence along the second direction.
[0013] Optionally, in the method of forming the modulator, an N++ germanium-silicon layer, an N+ germanium-silicon layer, a P+ germanium-silicon layer, and a P++ germanium-silicon layer are epitaxially formed inside and outside the first trench.
[0014] Optionally, in the method of forming the modulator, the method of forming a second trench in the dielectric layer and substrate on both sides of each first trench includes:
[0015] The dielectric layer is dry-etched until it stops at the surface of the substrate.
[0016] The substrate, a portion of its thickness, is wet-etched to form a second trench.
[0017] Optionally, in the method of forming the modulator, the second trench is arranged radially symmetrically about the first trench.
[0018] Optionally, in the method of forming the modulator, the dielectric layer comprises silicon oxide.
[0019] The present invention also provides a modulator, comprising:
[0020] Substrate;
[0021] A dielectric layer located on the surface of the substrate;
[0022] A plurality of first trenches extending along a first direction and spaced apart along a second direction are located within the dielectric layer and the substrate, wherein the first direction and the second direction are perpendicular to each other;
[0023] A modulator structure located within the first trench, the modulator structure comprising stacked N++ germanium-silicon layers, N+ germanium-silicon layers, a quantum well, a P+ germanium-silicon layer, and a P++ germanium-silicon layer, wherein the quantum well comprises at least three combinations of stacked germanium material layers and germanium-silicon material layers, wherein in each combination, the germanium-silicon material layer is located on the surface of the germanium material layer;
[0024] The modulator structure is suspended on the second trenches located in the dielectric layer and substrate on both sides of each of the first trenches along the second direction, and the lengths of each of the second trenches are different in the first direction.
[0025] The present invention also provides a method for forming a modulator, comprising:
[0026] A plurality of first trenches extending along a first direction and spaced apart along a second direction are formed in the dielectric layer and the substrate, wherein the first direction and the second direction are perpendicular to each other;
[0027] A modulator structure is formed in the first trench. The modulator structure includes stacked N++ germanium-silicon layers, N+ germanium-silicon layers, quantum wells, P+ germanium-silicon layers, and P++ germanium-silicon layers. The quantum well includes at least three combinations of stacked germanium material layers and germanium-silicon material layers. In each combination, the germanium-silicon material layer is located on the surface of the germanium material layer.
[0028] A second trench is formed in the dielectric layer and substrate on both sides of each of the first trenches along the second direction, and the modulator structure is suspended on the second trenches, and each of the second trenches has the same length in the first direction;
[0029] A germanium-silicon layer is formed in the second trench, and the content of germanium material in the germanium-silicon layer in each of the second trenches is different.
[0030] Optionally, in the method for forming the modulator, the content of germanium material in the germanium-silicon layer increases sequentially along the second direction.
[0031] Optionally, in the method for forming the modulator, as the number of columns changes, the content of germanium material in the germanium-silicon layer increases sequentially along the second direction in an arithmetic progression.
[0032] The present invention also provides a modulator, comprising:
[0033] Substrate;
[0034] A dielectric layer located on the surface of the substrate;
[0035] A plurality of first trenches extending along a first direction and spaced apart along a second direction are located within the dielectric layer and the substrate, wherein the first direction and the second direction are perpendicular to each other;
[0036] A modulator structure located within the first trench, the modulator structure comprising stacked N++ germanium-silicon layers, N+ germanium-silicon layers, a quantum well, a P+ germanium-silicon layer, and a P++ germanium-silicon layer, wherein the quantum well comprises at least three combinations of stacked germanium material layers and germanium-silicon material layers, wherein in each combination, the germanium-silicon material layer is located on the surface of the germanium material layer;
[0037] The modulator structure is suspended on the second trenches, which are located in the dielectric layer and substrate on both sides of each of the first trenches along the second direction, and each of the second trenches has the same length in the first direction.
[0038] The germanium-silicon layer located in the second trench has a different germanium content in each of the second trenches.
[0039] In the modulator and its formation method provided by this invention, a modulator structure is formed within a first trench. Then, a second trench is formed on both sides of each first trench along a second direction, suspending the modulator structure on the second trenches. The lengths of the second trenches in the first direction are not equal. Alternatively, the lengths of the second trenches in the first direction are equal, but the germanium content in the germanium-silicon layer within the second trenches is different. Both methods generate different tensile stresses on the quantum well, thereby obtaining absorption edges with different operating wavelengths. Therefore, compared to the prior art of applying different bias voltages to different modulators, this invention does not generate dark current or change the light absorption coefficient of the modulator. It still improves the absorption contrast between modulators while reducing heat damage. Attached Figure Description
[0040] Figure 1 This is a flowchart of the method for forming a modulator according to Embodiment 1 of the present invention;
[0041] Figure 2 This is a schematic diagram of the modulator after the first trench is formed according to Embodiment 1 of the present invention;
[0042] Figure 3 This is a cross-sectional schematic diagram of the modulator after the first trench is formed according to Embodiment 1 of the present invention;
[0043] Figure 4 This is a schematic diagram of the modulator structure after forming the P++ germanium-silicon layer according to Embodiment 1 of the present invention;
[0044] Figure 5 This is a schematic diagram of the modulator structure after the second trench is formed according to Embodiment 1 of the present invention;
[0045] Figure 6 This is a flowchart of the method for forming the modulator according to Embodiment 2 of the present invention;
[0046] Figure 7 This is a schematic diagram of the modulator structure after forming the P++ germanium-silicon layer according to Embodiment 2 of the present invention;
[0047] Figure 8 This is a schematic diagram of the modulator structure after the second trench is formed according to Embodiment 2 of the present invention;
[0048] Figure 9This is a schematic diagram of the modulator structure after the formation of the germanium-silicon layer in Embodiment 2 of the present invention;
[0049] In the figure: 101-substrate, 102-dielectric layer, 103-first trench, 104-N++ germanium-silicon layer, 105-N+ germanium-silicon layer, 106-quantum well, 107-P+ germanium-silicon layer, 108-P++ germanium-silicon layer, 109-second trench, 201-substrate, 202-dielectric layer, 404-N++ germanium-silicon layer, 205-N+ germanium-silicon layer, 206-quantum well, 207-P+ germanium-silicon layer, 208-P++ germanium-silicon layer, 209-second trench, 210-second germanium-silicon layer. Detailed Implementation
[0050] The specific embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.
[0051] In the following text, the terms “first,” “second,” etc., are used to distinguish between similar elements and are not necessarily used to describe a specific order or chronological sequence. It should be understood that these terms, as used herein, may be replaced where appropriate. Similarly, if the methods described herein comprise a series of steps, and the order of these steps presented herein is not necessarily the only possible order in which they can be performed, and some described steps may be omitted and / or other steps not described herein may be added to the method.
[0052] Furthermore, it should be understood that when a layer (or film), region, pattern, or structure is referred to as being "on" a substrate, layer (or film), region, and / or pattern, it can be located directly on another layer or substrate, and / or intercalation layers may also be present. Additionally, it should be understood that when a layer is referred to as being "under" another layer, it can be located directly under that layer, and / or one or more intercalation layers may also be present. Furthermore, references to "on" and "under" the layers may be made based on the accompanying drawings.
[0053] Example 1
[0054] This invention provides a method for forming a modulator, comprising:
[0055] S11: Provide a substrate and form a dielectric layer on the surface of the substrate;
[0056] S12: A plurality of first trenches extending along a first direction and spaced apart along a second direction are formed in the dielectric layer and the substrate, wherein the first direction and the second direction are perpendicular to each other;
[0057] S13: A modulator structure is formed in the first trench. The modulator structure includes stacked N++ germanium-silicon layers, N+ germanium-silicon layers, quantum wells, P+ germanium-silicon layers and P++ germanium-silicon layers. The quantum well includes at least three sets of combinations of germanium material layers and germanium-silicon material layers stacked. In each combination, the germanium-silicon material layer is located on the surface of the germanium material layer.
[0058] S14: A second trench is formed in the dielectric layer and substrate on both sides of each first trench along the second direction, and the modulator structure is suspended on the second trench. The lengths of each second trench in the first direction are different.
[0059] Please refer to Figure 2 First, a substrate 101 is provided, which can be SOI. Organic contaminants are removed from the SOI using SC1 solution. Then, metal ion contaminants are removed using SC2 solution. Finally, the native oxide film on the SOI surface is removed using HF solution. Next, a silicon dioxide layer is grown on the cleaned SOI as a dielectric layer 102 using plasma-enhanced chemical vapor deposition (PECVD).
[0060] Next, please refer to Figure 2 A highly selective and directional ICP etching technique is used to etch the dielectric layer 102 and a portion of the substrate 101 to form several first trenches 103. The first trenches 103 extend along a first direction and are spaced apart along a second direction. The first and second directions are perpendicular to each other, and the cross-section of the first trenches 103 is strip-shaped. Choosing a highly selective and directional ICP etching technique can obtain better etching directionality and improve the etching rate. At the same time, appropriately increasing the etching temperature during the etching process can prevent the deposition of polymers generated during etching on the surface.
[0061] Next, please continue to refer to Figure 4 An N++ germanium-silicon layer 104 (N++GeSi) is epitaxially formed in the first trench 103 using a reduced-pressure vapor phase epitaxy method. In this embodiment, the epitaxial growth temperature is 650℃~670℃, the pressure is 15Toor~20Toor, and the reaction gases are germanane (GeH4) and dichlorosilane (DCS). During epitaxy, arsine (AsH3) and phosphine (PH3) doping gases are used for in-situ n-type heavy doping. Then, in-situ annealing is performed at 800℃~850℃.
[0062] Next, please continue to refer to Figure 4 An N+ germanium silicon layer 105 is epitaxially grown on the surface of the N++ germanium silicon layer 104, and in-situ n-type doping is performed using doping gases arsine (AsH3) and phosphine (PH3) during epitaxy.
[0063] Next, please continue to refer to Figure 4A quantum well 106 is epitaxially formed on the surface of the N+ germanium-silicon layer 105. The quantum well 106 requires high crystal quality and its growth rate must be strictly controlled. Therefore, in this embodiment of the invention, both the germanium and germanium-silicon material layers in the quantum well 106 are grown using depressurized vapor phase epitaxy. Specifically, a germanium material layer can be epitaxially formed, followed by another germanium-silicon material layer. Then, another germanium material layer can be epitaxially formed, followed by yet another germanium-silicon material layer. At least one combination of germanium and germanium-silicon material layers is formed by alternating epitaxial formation of these layers, with the germanium-silicon material layer located on the surface of the germanium material layer in each combination. The number of combinations is typically 3 to 10, depending on the specific circumstances.
[0064] Next, please continue to refer to Figure 4 A P+ germanium-silicon layer 107 is epitaxially formed on the surface of the quantum well 106. The epitaxial growth temperature can be 650℃~670℃, the pressure can be 15Toor~20Toor, the reaction gases are germanane (GeH4) and dichlorosilane (DCS), and borane (B2H6) is used for in-situ P-type doping during epitaxy.
[0065] Next, please continue to refer to Figure 4 A P++ germanium-silicon layer 108 is epitaxially formed on the surface of the P+ germanium-silicon layer 107, and P-type in-situ heavy doping is performed using borane (B2H6) doping gas during epitaxy. The stacked N++ germanium-silicon layer 104, N+ germanium-silicon layer 105, quantum well 106, P+ germanium-silicon layer 107 and P++ germanium-silicon layer 108 constitute the modulator structure.
[0066] Next, please refer to Figure 5 , Figure 4 It is along Figure 5The longitudinal section formed along the AA direction shows the surface of the P++ germanium-silicon layer 108 exposed in the first trench. Starting from the surface of the dielectric layer 102 on both sides of each first trench along the second direction, the dielectric layer 102 is dry-etched to expose the surface of the substrate. The etching gas can be C4F8 (with a small amount of H) and Cl gas. Then, a portion of the substrate 101 is wet-etched using a 5%–8% TMAH solution to form a second trench 109. The second trench 109 is close to the middle portion of the first trench and exposes part of the sidewalls and bottom wall of the modulator structure. The second trench 109 is radially symmetrical about the first trench. The modulator structure is suspended on the second trench 109. After the N++ germanium-silicon layer 104 loses the constraint of the substrate 101, the two ends of the modulator structure will exert uniaxial tension on the middle portion of the modulator structure, and the initial tensile strain of the quantum well 106 will be redistributed, thereby concentrating the strain in the middle portion of the modulator structure. The length L of the second trench 109 is not the same in the first direction. Specifically, the length L of the second trench 109 in the first direction increases sequentially along the second direction; more specifically, it can increase sequentially in an arithmetic sequence along the second direction. Different lengths result in different tensile stresses on the quantum well 106, different band structures in the quantum well 106, and consequently, different light absorption edges. Generally, the greater the length, the greater the tensile stress on the quantum well 106, the larger the absorption edge, and the greater the bandwidth obtained.
[0067] Please refer to Figure 4 and Figure 5 Embodiment 1 also provides a modulator, including: a substrate 101; a dielectric layer 102 located on the surface of the substrate 101; a plurality of first trenches located in the dielectric layer 102 and the substrate 101 extending along a first direction and spaced apart along a second direction, the first direction and the second direction being perpendicular to each other; a modulator structure located in the first trenches, the modulator structure including stacked N++ germanium-silicon layers 104, N+ germanium-silicon layers 105, quantum wells 106, P+ germanium-silicon layers 107 and P++ germanium-silicon layers 108, wherein the quantum well 106 includes at least three sets of combinations of germanium material layers and germanium-silicon material layers stacked together, in each set, the germanium-silicon material layer is located on the surface of the germanium material layer; second trenches 109 located in the dielectric layer 102 and the substrate 101 on both sides of each first trench along the second direction, the modulator structure being suspended on the second trenches 109, the lengths of each second trench 109 being different in the first direction.
[0068] Example 2
[0069] Please refer to Figure 6 The present invention also provides a method for forming a modulator, comprising:
[0070] S21: Provide a substrate and form a dielectric layer on the surface of the substrate;
[0071] S22: A plurality of first trenches extending along a first direction and spaced apart along a second direction are formed in the dielectric layer and the substrate, wherein the first direction and the second direction are perpendicular to each other;
[0072] S23: A modulator structure is formed in the first trench. The modulator structure includes stacked N++ germanium-silicon layers, N+ germanium-silicon layers, quantum wells, P+ germanium-silicon layers and P++ germanium-silicon layers. The quantum well includes a combination of at least three stacked germanium material layers and germanium-silicon material layers. In each combination, the germanium-silicon material layer is located on the surface of the germanium material layer.
[0073] S24: A second trench is formed in the dielectric layer and substrate on both sides of each first trench along the second direction, and the modulator structure is suspended on the second trench. The length of each second trench is the same in the first direction.
[0074] S25: A germanium-silicon layer is formed in the second trench, and the content of germanium material in the germanium-silicon layer in each second trench is different.
[0075] Example 2 uses the same method as Example 1 to form a modulator structure consisting of an N++ germanium-silicon layer, an N+ germanium-silicon layer, a quantum well, a P+ germanium-silicon layer, and a P++ germanium-silicon layer in the first trench, which will not be described in detail here.
[0076] Next, please refer to Figure 7 The surface of the P++ germanium-silicon layer 208 is exposed in the first trench. Starting from the surface of the dielectric layer 202 on both sides of each first trench along the second direction, the dielectric layer is dry-etched to expose the surface of the substrate. The etching gas can be C4F8 (with a small amount of H) and Cl gas. Then, a portion of the substrate thickness is wet-etched using a 5% TMAH solution to form a second trench 209, which is radially symmetrical about the first trench. The second trenches 209 have the same length L in the first direction.
[0077] Next, please refer to Figure 7 and Figure 8 A germanium-silicon layer 210 is epitaxially formed inside and outside the second trench 209, and the germanium content in the germanium-silicon layer 210 within each second trench 209 is different. Specifically, the germanium content in the germanium-silicon layer 210 increases sequentially along the second direction. More specifically, the germanium content in the germanium-silicon layer 210 can increase sequentially along the second direction in an arithmetic progression. Different germanium contents result in different tensile stresses on the quantum well 206, leading to different band structures and ultimately different absorption edges. Generally, the higher the germanium content, the greater the compressive stress in the middle part of the quantum well 206, and the larger the absorption edge.
[0078] Please refer to Figures 7 to 9Embodiment 2 also provides a modulator, comprising: a substrate 201; a dielectric layer 202 located on the surface of the substrate; a plurality of first trenches located in the dielectric layer 202 and the substrate 201 extending along a first direction and spaced apart along a second direction, the first direction and the second direction being perpendicular to each other; a modulator structure located in the first trenches, the modulator structure comprising stacked N++ germanium-silicon layers 204, N+ germanium-silicon layers 205, quantum wells 206, P+ germanium-silicon layers 207 and P++ germanium-silicon layers 208, wherein the quantum well 206 comprises at least three sets of combinations of germanium material layers and germanium-silicon material layers stacked together, in each set of combinations, the germanium-silicon material layer being located on the surface of the germanium material layer; second trenches located in the dielectric layer 202 and the substrate 201 on both sides of each first trench along the second direction, the modulator structure being suspended on the second trenches, each second trench having the same length in the first direction; and a germanium-silicon layer 210 located in the second trenches, the germanium content in each second trench being different.
[0079] In summary, in the modulator and its formation method provided in this embodiment of the invention, a modulator structure is formed within a first trench. Then, a second trench is formed on both sides of each first trench along a second direction, suspending the modulator structure on the second trenches. The lengths of the second trenches in the first direction are not the same. Alternatively, the lengths of the second trenches in the first direction are the same, but the germanium content in the germanium-silicon layer within the second trench is different. Both methods generate different tensile stresses on the quantum well, thereby obtaining absorption edges with different operating wavelengths. Therefore, compared to the prior art of applying different bias voltages to different modulators, this invention does not generate dark current or change the light absorption coefficient of the modulator. It still improves the absorption contrast between modulators while reducing heat damage.
[0080] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.
Claims
1. A method of forming a modulator, characterized by, include: A substrate is provided, and a dielectric layer is formed on the surface of the substrate; A plurality of first trenches extending along a first direction and spaced apart along a second direction are formed in the dielectric layer and the substrate, wherein the first direction and the second direction are perpendicular to each other; A modulator structure is formed in the first trench. The modulator structure includes stacked N++ germanium-silicon layers, N+ germanium-silicon layers, quantum wells, P+ germanium-silicon layers, and P++ germanium-silicon layers. The quantum well includes at least three combinations of stacked germanium material layers and germanium-silicon material layers. In each combination, the germanium-silicon material layer is located on the surface of the germanium material layer. A second trench is formed in the dielectric layer and substrate on both sides of each of the first trenches along the second direction, and the modulator structure is suspended on the second trenches. The lengths of each of the second trenches are different in the first direction.
2. The method of claim 1, wherein the modulator is formed by: The length of each of the second grooves increases sequentially along the second direction from the first direction.
3. The method of claim 2, wherein the modulator is formed by: The length of each of the second grooves in the extension direction of the first groove increases sequentially in an arithmetic sequence along the second direction.
4. The method for forming a modulator as described in claim 1, characterized in that, An N++ germanium-silicon layer, an N+ germanium-silicon layer, a P+ germanium-silicon layer, and a P++ germanium-silicon layer are epitaxially formed inside and outside the first trench.
5. The method for forming a modulator as described in claim 1, characterized in that, The method for forming a second trench in the dielectric layer and substrate on both sides of each first trench includes: The dielectric layer is dry-etched until it stops at the surface of the substrate. The substrate, a portion of its thickness, is wet-etched to form a second trench.
6. The method for forming a modulator as described in claim 1, characterized in that, The second groove is arranged radially symmetrically with respect to the first groove.
7. The method for forming a modulator as described in claim 1, characterized in that, The dielectric layer comprises silicon oxide.
8. A modulator, characterized in that, include: Substrate; A dielectric layer located on the surface of the substrate; A plurality of first trenches extending along a first direction and spaced apart along a second direction are located within the dielectric layer and the substrate, wherein the first direction and the second direction are perpendicular to each other; A modulator structure located within the first trench, the modulator structure comprising stacked N++ germanium-silicon layers, N+ germanium-silicon layers, a quantum well, a P+ germanium-silicon layer, and a P++ germanium-silicon layer, wherein the quantum well comprises at least three combinations of stacked germanium material layers and germanium-silicon material layers, wherein in each combination, the germanium-silicon material layer is located on the surface of the germanium material layer; The modulator structure is suspended on the second trenches, which are located in the dielectric layer and substrate on both sides of each of the first trenches along the second direction, and the lengths of each of the second trenches are different in the first direction.
9. A method for forming a modulator, characterized in that, include: A plurality of first trenches extending along a first direction and spaced apart along a second direction are formed in the dielectric layer and the substrate, wherein the first direction and the second direction are perpendicular to each other; A modulator structure is formed in the first trench. The modulator structure includes stacked N++ germanium-silicon layers, N+ germanium-silicon layers, quantum wells, P+ germanium-silicon layers, and P++ germanium-silicon layers. The quantum well includes at least three combinations of stacked germanium material layers and germanium-silicon material layers. In each combination, the germanium-silicon material layer is located on the surface of the germanium material layer. A second trench is formed in the dielectric layer and substrate on both sides of each of the first trenches along the second direction, and the modulator structure is suspended on the second trenches, and each of the second trenches has the same length in the first direction; A germanium-silicon layer is formed in the second trench, and the content of germanium material in the germanium-silicon layer in each of the second trenches is different.
10. The method for forming a modulator as described in claim 9, characterized in that, The germanium content in the germanium-silicon layer increases sequentially along the second direction.
11. The method for forming a modulator as described in claim 10, characterized in that, As the number of columns changes, the content of germanium material in the germanium-silicon layer increases sequentially along the second direction in an arithmetic progression.
12. A modulator, characterized in that, include: Substrate; A dielectric layer located on the surface of the substrate; A plurality of first trenches extending along a first direction and spaced apart along a second direction are located within the dielectric layer and the substrate, wherein the first direction and the second direction are perpendicular to each other; A modulator structure located within the first trench, the modulator structure comprising stacked N++ germanium-silicon layers, N+ germanium-silicon layers, a quantum well, a P+ germanium-silicon layer, and a P++ germanium-silicon layer, wherein the quantum well comprises at least three combinations of stacked germanium material layers and germanium-silicon material layers, wherein in each combination, the germanium-silicon material layer is located on the surface of the germanium material layer; The modulator structure is suspended on the second trenches, which are located in the dielectric layer and substrate on both sides of each of the first trenches along the second direction, and each of the second trenches has the same length in the first direction. The germanium-silicon layer located in the second trench has a different germanium content in each of the second trenches.