Light-operated metasurface structure and manufacturing method thereof

Abstract

The invention discloses a light-operated metasurface structure and a manufacturing method thereof, the light-operated metasurface structure comprises a composite dielectric layer, the composite dielectric layer comprises a silicon nitride silicon carbide layer, an oxide layer and a silicon nitride layer which are stacked from bottom to top, and a first metal handrail is composed of a base and a metal strip. Wherein the first metal handrail embedded in the silicon oxide layer and the silicon nitride layer is defined as a base, the first metal handrail embedded in the silicon nitride layer and protruding out of the silicon nitride layer is defined as a metal strip, and the width of the base in the silicon oxide layer is continuously and gradually increased towards the direction of the silicon nitride layer. A second metal handrail is arranged on one side of the first metal handrail, the second metal handrail and the first metal handrail are the same in structure, a gap is formed between the first metal handrail and the second metal handrail, and the gap is filled with a plurality of liquid crystals.

Description

TECHNICAL FIELD

[0001] The present application relates to a light control metasurface structure and a manufacturing method thereof, in particular to a manufacturing method for avoiding the metal rail in the light control metasurface structure from falling down during etching. BACKGROUND

[0002] Optical radar is a sensing technology that emits low-power, eye-safe laser light to measure the time it takes for a round trip between the sensor and the target. Optical radar can be applied in home security systems, barcode scanners, and facial recognition systems, and its application in fully autonomous driving is also promising. Unlike radar and sonar, optical radar provides high-resolution three-dimensional data, making it an important tool for industries such as automotive, geology, and agriculture.

[0003] Light control metasurface (LCM) is a semiconductor chip that deflects laser pulses based on the principle of light refraction of materials. This technology is used in optical radar technology, which can improve its sensing capabilities, while benefiting from the characteristics of semiconductor manufacturing to reduce production costs. SUMMARY

[0004] Therefore, the present application provides a manufacturing method of a light control metasurface structure to improve the yield of the light control metasurface structure.

[0005] According to a preferred embodiment of the present application, a light control metasurface structure includes a composite dielectric layer, wherein the composite dielectric layer includes a nitrogen-doped silicon carbide layer, an oxide layer, and a silicon nitride layer stacked from bottom to top, a first metal rail composed of a base and a metal strip, wherein the first metal rail embedded in the silicon oxide layer and the nitrogen-doped silicon carbide layer is defined as a base, the first metal rail embedded in the silicon nitride layer and protruding above the silicon nitride layer is defined as a metal strip, the metal strip has a top surface, the width of the metal strip gradually decreases along the direction of the top surface towards the base, the width of the base in the silicon oxide layer continuously increases along the direction towards the nitrogen-doped silicon carbide layer, a second metal rail is arranged on one side of the first metal rail, the second metal rail has the same structure as the first metal rail, a gap is arranged between the first metal rail and the second metal rail, and a plurality of liquid crystals fill the gap.

[0006] According to another preferred embodiment of the present invention, a method for fabricating a light-controlled metasurface structure includes providing a first dielectric layer, a composite dielectric layer, and a second dielectric layer stacked from bottom to top, wherein the composite dielectric layer comprises a silicon carbide nitride layer, an oxide layer, and a silicon nitride layer stacked from bottom to top; then forming a first trench to bury the second dielectric layer and the silicon nitride layer; after forming the first trench, performing an isotropic etching process with a first etchant to etch the silicon oxide layer so that the bottom of the first trench extends into the silicon oxide layer; after the isotropic etching process, performing an anisotropic etching process with a second etchant to etch the silicon carbide nitride layer so that the bottom of the first trench extends into the silicon carbide nitride layer; after the anisotropic etching process, forming a diffusion barrier layer to cover the first trench; after forming the diffusion barrier layer, forming a metal layer to fill the first trench; finally removing all of the second dielectric layer and the diffusion barrier layer in the second dielectric layer to form a void; and finally providing a plurality of liquid crystals to fill the void.

[0007] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings. However, the following preferred embodiments and drawings are for reference and illustration only and are not intended to limit the present invention. Attached Figure Description

[0008] Figures 1 to 7 This is a schematic diagram illustrating a method for fabricating a light-controlled metasurface structure according to a preferred embodiment of the present invention.

[0009] Symbol Explanation

[0010] 10: First dielectric layer

[0011] 10a: Silicon oxide layer

[0012] 10b: Silicon carbide nitride layer

[0013] 12: Composite dielectric layer

[0014] 12a: Silicon carbide nitride layer

[0015] 12b: Oxide layer

[0016] 12c: Silicon nitride layer

[0017] 14: Second dielectric layer

[0018] 16: First conductor

[0019] 18: First plug

[0020] 20: First trench

[0021] 20a: Corner

[0022] 22: Second trench

[0023] 22a: Corner

[0024] 24: Diffusion barrier layer

[0025] 26: Metal layer

[0026] 28: Mask layer

[0027] 30: Protective layer

[0028] 32: LCD

[0029] 34a: First metal railing

[0030] 34b: Second metal railing

[0031] 36: Base

[0032] 38: Metal strip

[0033] 40: Copper conductor structure

[0034] 42: Second conductor

[0035] 44: Reflective layer

[0036] 100: Light-controlled metasurface structure

[0037] A: Logic element area

[0038] B: Optical Components Area

[0039] W1: Width

[0040] W2: Width

[0041] W3: Width

[0042] W4: Width

[0043] W5: Width

[0044] W6: Width Detailed Implementation

[0045] Figures 1 to 7 This is a method for fabricating a light-controlled metasurface structure according to a preferred embodiment of the present invention.

[0046] like Figure 1As shown, a first dielectric layer 10, a composite dielectric layer 12, and a second dielectric layer 14 are stacked from bottom to top. The composite dielectric layer 12 comprises a silicon carbide nitride layer 12a, an oxide layer 12b, and a silicon nitride layer 12c stacked from bottom to top. The first dielectric layer 10, the composite dielectric layer 12, and the second dielectric layer 14 are each divided into a logic element region A and an optical element region B. A first conductor 16 and a first plug 18 are disposed in the logic element region A of the first dielectric layer 10. The first plug 18 is on the first conductor 16. A reflective layer 44 is disposed in the optical element region B of the first dielectric layer 10. The upper surface of the first conductor 16 and the upper surface of the reflective layer 44 are flush.

[0047] like Figure 2 As shown, a first trench 20 and a second trench 22 are formed simultaneously. The first trench 20 is embedded in the second dielectric layer 14 and the silicon nitride layer 12c in the optical element region B, and the second trench 22 is embedded in the second dielectric layer 14 and the silicon nitride layer 12c in the logic element region A. According to a preferred embodiment of the present invention, the first trench 20 and the second trench 22 can be etched by using an anisotropic etching agent containing carbon tetrafluoride (CF4) to etch the second dielectric layer 14, and then etch the silicon nitride layer 12c with an etchant containing hexafluorobutadiene (C4F6). At this time, the bottom of the first trench 20 and the bottom of the second trench 22 are both located in the silicon nitride layer 12c. The number of the first trench 20 and the second trench 22 is not limited, but the number of the first trench 20 is preferably two or more.

[0048] like Figure 3 As shown, an isotropic etching process using a first etchant etches the silicon oxide layer 12b located at the bottom of the first trench 20 and the bottom of the second trench 22, so that the bottoms of the first trench 20 and the second trench 22 each extend into the silicon oxide layer 12b. The first etchant contains carbon tetrafluoride (CF4). Due to the isotropic etching, during the etching of the silicon oxide layer 12b, the width of the bottom of the first trench 20 and the bottom of the second trench 22 continuously and gradually expands outward. At this time, the bottoms of the first trench 20 and the bottom of the second trench 22 are both located within the silicon oxide layer 12b. Furthermore, since the second dielectric layer 14 is preferably silicon oxide in this embodiment, it is also etched by the first etchant. Therefore, during the isotropic etching process, the openings of the first trench 20 and the second trench 22 are enlarged, thus forming a corner 20a / 22a on the sidewalls of the first trench 20 and the second trench 22 near the opening.

[0049] like Figure 4As shown, after the isotropic etching process, an anisotropic etching process is performed using a second etchant to etch the silicon carbide nitride layer 12a, extending the bottom of the first trench 20 and the bottom of the second trench 22 into the silicon carbide nitride layer 12a. The second etchant contains trifluoromethane (CHF3). Since it is an anisotropic etching process, during the etching of the silicon carbide nitride layer, the width of the bottom of the first trench 20 and the width of the bottom of the second trench 22 will continuously and gradually decrease inward. The anisotropic etching process stops when it contacts the first dielectric layer 10 or the first plug 18, thus completing the first trench 20 and the second trench 22.

[0050] like Figure 5 As shown, a diffusion barrier layer 24 is first formed to conformally cover the first trench 20 and the second trench 22. The diffusion barrier layer 24 in the second trench 22 contacts the first plug 18. Then, a metal layer 26 is formed and filled into the first trench 20 and the second trench 22. The metal layer 26 in the first trench 20 will serve as the metal rail of the photosensitive metasurface structure, and the metal layer 26 in the second trench 22 will serve as the conductor within the logic element area A. Figure 2 Steps to Figure 5 The preferred approach is to use a copper inlay fabrication process to simultaneously fabricate the wires for logic element area A and the metal railings for optical element area B, thus simplifying the fabrication process for optical element area B.

[0051] like Figure 6 As shown, a mask layer 28 is formed to cover the logic element region A, exposing the optical element region B. Then, all of the second dielectric layer 14 and the diffusion barrier layer 24 within the second dielectric layer 14 are removed from the optical element region B to form a gap 28. Preferably, anisotropic etching is used to remove the second dielectric layer 14. At this point, the silicon nitride layer 12c and the metal layer 26 are exposed through the gap 28. Figure 7 As shown, the mask layer 28 is removed, and then a protective layer 30 is formed to cover and contact the metal layer 26 and the silicon nitride layer 12c. Subsequently, a plurality of liquid crystals 32 are provided to fill the gaps 28, and the light-controlled metasurface structure 100 of the present invention is now complete.

[0052] like Figure 7As shown, a light-controlled metasurface structure 100 of the present invention includes a first dielectric layer 10, a composite dielectric layer 12, and a second dielectric layer 14 stacked from bottom to top, with the composite dielectric layer 12 contacting the first dielectric layer 10 and the second dielectric layer 14. Furthermore, the composite dielectric layer 12 includes a silicon carbide nitride layer 12a, an oxide layer 12b, and a silicon nitride layer 12c stacked from bottom to top, with the oxide layer 12b contacting the silicon carbide nitride layer 12a and the silicon nitride layer 12c. The first dielectric layer 10 is a multilayer dielectric material, such as a material layer consisting of alternating stacks of silicon oxide layer 10a and silicon carbide nitride layer 10b. The second dielectric layer 14 is preferably silicon oxide. The first dielectric layer 10, the composite dielectric layer 12, and the second dielectric layer 14 are all divided into a logic element region A and an optical element region B.

[0053] A first metal rail 34a and a second metal rail 34b are disposed within the optical element area B, with the second metal rail 34b positioned to one side of the first metal rail 34a. A copper wire structure 40 is disposed within the logic element area A. Since the structures of the first metal rail 34a and the second metal rail 34b are identical, only the structure of the first metal rail 34a will be described. The structure and material of the second metal rail 34b are described in reference to the first metal rail 34a.

[0054] The first metal railing 34a consists of a base 36 and a metal strip 38. The first metal railing 34a embedded in the silicon oxide layer 12b and the silicon carbide nitride layer 12a is defined as the base 36. The first metal railing 34a embedded in the silicon nitride layer 12c and protruding above the silicon nitride layer 12c is defined as a metal strip 38. The metal strip 38 has a top surface 38a. The width W1 of the metal strip 38 gradually decreases continuously along the top surface 38a toward the base 36. In addition, the metal strip 38 includes a side wall. The side wall adjacent to the top surface 38a has a corner 38b. The width W2 of the base 36 in the silicon oxide layer 12b gradually increases continuously along the direction toward the silicon carbide nitride layer 12c. The width W3 of the base 36 in the silicon carbide nitride layer 12c gradually decreases continuously along the direction toward the bottom of the base 36. A protective layer 30 covers and contacts a metal strip 38 protruding above the silicon nitride layer 12c. The protective layer 30 is preferably silicon nitride. A diffusion barrier layer 24 covers and contacts the base 36 and the metal strip 38 located within the silicon nitride layer 12c. The diffusion barrier layer 24 preferably comprises tantalum nitride, titanium nitride, titanium, or tantalum. The first metal railing 34a preferably comprises copper.

[0055] Additionally, a gap 28 is provided between the first metal railing 34a and the second metal railing 34b, and multiple liquid crystals 32 fill the gap 28, with the liquid crystals 32 in contact with the protective layer 30. Since the liquid crystals 32 are located between the first metal railing 34a and the second metal railing 34b, the orientation of the liquid crystals 32 can be controlled when a voltage is applied to the first metal railing 34a and the second metal railing 34b, thereby controlling the refraction direction of the incident wave. Furthermore, the aforementioned metal strip 38's angle 38b rotates towards the adjacent liquid crystal 32; in other words, the metal strip 38's angle 38b rotates outward, causing the metal strip 38 to widen towards the top surface 38a.

[0056] Furthermore, the copper conductor structure 40 includes a first conductor 16, a first plug 18, and a second conductor 42 stacked from bottom to top. The first conductor 16 and the first plug 18 are embedded in a first dielectric layer 10, and the second conductor 42 is embedded in a composite dielectric layer 12 and a second dielectric layer 14. The first conductor 16, the first plug 18, and the second conductor 42 preferably comprise copper and a diffusion barrier layer surrounding the copper. The diffusion barrier layer preferably comprises tantalum nitride, titanium nitride, titanium, or tantalum. The width W4 of the second conductor 42 within the silicon oxide layer 12b gradually increases continuously in the direction toward the silicon carbide nitride layer 12c. The end of the second conductor 42 is located in the silicon carbide nitride layer 12a. The width W5 of the second conductor 42 in the silicon carbide nitride layer 12a gradually decreases continuously in the direction toward the end of the second conductor 42 in the silicon carbide nitride layer 12a. The width W6 of the second conductor 42 in the second dielectric layer 14 gradually decreases continuously in the direction toward the silicon oxide layer 12b. In addition, the upper surface of the parallel composite dielectric layer 12 with widths W1 / W2 / W3 / W4 / W5 / W6.

[0057] Additionally, a reflective layer 44 is embedded in the first dielectric layer 10, located directly below the first metal railing 34a and the second metal railing 34b. Preferably, the reflective layer 44 and the first conductive wire 16 are manufactured using the same process, so the reflective layer 44 and the first conductive wire 16 are made of the same material; that is, the reflective layer 44 is also composed of copper and a diffusion barrier layer surrounding the copper. Furthermore, the upper surface of the first conductive wire 16 is flush with the upper surface of the reflective layer 44.

[0058] The first metal railing 34a and the second metal railing 34b of the present invention have a base 36 embedded in the composite dielectric layer 12. Therefore, when the second dielectric layer 14 is removed to form a gap 28, the first metal railing 34a and the second metal railing 34b can be fixed by the base 36 and will not tip over due to the etching process, thus increasing the yield of the light-controlled metasurface structure 100.

[0059] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made in accordance with the claims of the present invention should be included within the scope of the present invention.

Claims

1. A light-controlled metasurface (LCM) structure, comprising: A composite dielectric layer comprising a silicon carbide nitride layer, an oxide layer, and a silicon nitride layer stacked from bottom to top; A first metal railing, wherein the first metal railing consists of a base and a metal strip, the first metal railing embedded in the silicon oxide layer and the silicon carbide nitride layer is defined as the base, the first metal railing embedded in the silicon nitride layer and protruding above the silicon nitride layer is defined as the metal strip, and the width of the base in the silicon oxide layer gradually increases continuously along the direction toward the silicon carbide nitride layer. A second metal railing is installed on one side of the first metal railing, and the second metal railing has the same structure as the first metal railing. A gap is provided between the first metal railing and the second metal railing; as well as Multiple liquid crystals fill the gap.

2. The light-controlled metasurface structure as claimed in claim 1, wherein the metal strip has a top surface, and the width of the metal strip gradually decreases along the direction from the top surface toward the base.

3. The light-controlled metasurface structure as claimed in claim 1, wherein the metal strip includes a sidewall, and the sidewall adjacent to the top surface has a corner.

4. The light-controlled metasurface structure as described in claim 1, further comprising: A first dielectric layer is disposed below the composite dielectric layer; and A reflective layer is embedded in the first dielectric layer, wherein the reflective layer is located directly below the first metal railing and the second metal railing.

5. The light-controlled metasurface structure as described in claim 4, further comprising: A second dielectric layer is disposed above the composite dielectric layer; and A copper wire structure is embedded in a second dielectric layer, a composite dielectric layer, and a first dielectric layer, wherein the copper wire structure includes a first wire, a first plug, and a second wire stacked from bottom to top.

6. The light-controlled metasurface structure as claimed in claim 5, wherein the second conductive wire is embedded in the second dielectric layer and the composite dielectric layer, the width of the second conductive wire in the silicon oxide layer gradually increases continuously along the direction toward the silicon carbide nitride layer, and the end of the second conductive wire is located in the silicon carbide nitride layer.

7. The light-controlled metasurface structure as claimed in claim 5, wherein the upper surface of the first conductive wire and the upper surface of the reflective layer are flush.

8. The light-controlled metasurface structure of claim 1 further includes a protective layer contacting the metal strip protruding above the silicon nitride layer, wherein the liquid crystals contact the protective layer.

9. The light-controlled metasurface structure as claimed in claim 1, wherein the oxide layer contacts the silicon carbide nitride layer and the silicon nitride layer.

10. A method for fabricating a light-controlled metasurface (LCM) structure includes: A first dielectric layer, a composite dielectric layer, and a second dielectric layer are provided stacked from bottom to top, wherein the composite dielectric layer comprises a silicon carbide nitride layer, an oxide layer, and a silicon nitride layer stacked from bottom to top; A first trench is formed to embed the second dielectric layer and the silicon nitride layer; After the first trench is formed, the silicon oxide layer is etched using an isotropic etching process with a first etchant so that the bottom of the first trench extends into the silicon oxide layer. After the isotropic etching process, the silicon carbide nitride layer is etched by an anisotropic etching process using a second etchant so that the bottom of the first trench extends into the silicon carbide nitride layer. After the anisotropic etching process, a diffusion barrier layer is formed to cover the first trench. After the diffusion barrier layer is formed, a metal layer is formed to fill the first trench; as well as Remove all of the second dielectric layer and the diffusion barrier layer in the second dielectric layer to form a void; as well as Multiple liquid crystals are provided to fill the gap.

11. The method for fabricating a light-controlled metasurface structure as described in claim 10, wherein the step of embedding the first trench into the silicon nitride layer comprises etching the silicon nitride layer using an anisotropic etching process with a third etchant.

12. The method for fabricating a light-controlled metasurface structure as described in claim 11, wherein the third etchant comprises hexafluorobutadiene (C4F6).

13. The method for fabricating a light-controlled metasurface structure as described in claim 10, wherein the first etchant comprises carbon tetrafluoride (CF4) and the second etchant comprises trifluoromethane (CHF3).

14. The method for fabricating a light-controlled metasurface structure as described in claim 10 further includes forming a first conductive wire, a first plug, and a second conductive wire stacked from bottom to top, wherein the first conductive wire and the first plug are embedded in the first dielectric layer, and the second conductive wire is embedded in the composite dielectric layer and the second dielectric layer.

15. The method for fabricating a light-controlled metasurface structure as described in claim 14, further comprising: When the first trench is formed, a second trench is simultaneously formed to embed the second dielectric layer and the silicon nitride layer; After the second trench is formed, the isotropic etching process is performed using the first etchant to etch the silicon oxide layer so that the bottom of the second trench extends into the silicon oxide layer. After the isotropic etching process, the silicon carbide nitride layer is etched by the anisotropic etching process using the second etchant so that the bottom of the second trench extends into the silicon carbide nitride layer. After the anisotropic etching process, the diffusion barrier layer is formed to cover the second trench. as well as After the diffusion barrier layer is formed, the metal layer is formed and filled into the second trench to form the second conductor.

16. The method for fabricating a light-controlled metasurface structure as described in claim 15, wherein the diffusion barrier layer within the second trench contacts the first plug.

17. The method for fabricating a light-controlled metasurface structure as described in claim 14, further comprising simultaneously forming a reflective layer and embedding the first conductive wire into the first dielectric layer, wherein the reflective layer is located directly below the first trench, and the upper surface of the first conductive wire is flush with the upper surface of the reflective layer.

18. The method for fabricating a light-controlled metasurface structure as described in claim 10, wherein the opening of the first trench is enlarged during the isotropic etching process.

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