High-directivity waveguide grating antenna and preparation method therefor

Abstract

A high-directivity waveguide grating antenna and a preparation method therefor. The waveguide grating antenna comprises an upper layer and a lower layer; the lower layer is a wafer layer, and the upper layer is a grating layer (1); a waveguide pattern (2) is provided on the top surface of the wafer layer; a shallow-etched grating (3) is provided in the middle of the top surface of the grating layer (1); side gratings (4) are provided on two sides of the shallow-etched grating (3). Compared with the method of staggered etching of grating grooves of different depths, and forming grating patterns on the upper and lower surface of a waveguide and staggering the grating patterns in the extension direction of a grating, the present invention can save a layer of photolithography mask and reduce manufacturing costs.

Description

A high-directivity waveguide grating antenna and its preparation method Technical Field

[0001] The present invention relates to the technical field of integrated optoelectronic devices, and in particular to a highly directional waveguide grating antenna and a preparation method thereof. Background Art

[0002] A waveguide grating is a unit cell device used to transmit light from a waveguide into free space. It is commonly used as the transmitting antenna for optical phased arrays, achieving pure solid-state beam control. Conventional waveguide gratings are typically formed by etching away a portion of the waveguide layer from the upper surface of the waveguide. However, such gratings can leak a significant amount of light into the substrate, resulting in high insertion loss in the optical phased array, limiting the detection range. Furthermore, such gratings have a short effective transmission length, which can lead to poor detection resolution. Common methods for reducing light leakage into the substrate include adding a reflective structure beneath the grating, staggering grating grooves of varying depths (patent "A Multi-layer Waveguide Grating Antenna Based on Staggered Etching for Optical Phased Array Applications and Its Fabrication Method," Publication No. CN115220150A), or forming grating patterns on the upper and lower surfaces of the waveguide, staggered by a certain length along the grating extension direction. While these methods can improve grating directivity, they increase process complexity, the number of photolithography masks, and manufacturing costs. There is a need for simpler and more cost-effective methods to improve grating directivity.

[0003] Summary of the Invention

[0004] The purpose of the present invention is to provide a highly directional waveguide grating antenna and a preparation method thereof, so as to solve the technical problem in the prior art that the grating directivity can be improved but the process complexity is increased, the number of photolithography masks is increased, and the manufacturing cost is increased.

[0005] The present invention discloses a highly directional waveguide grating antenna, comprising an upper layer and a lower layer, wherein the lower layer is a wafer layer, the upper layer is a grating layer, the top surface of the wafer layer is provided with a waveguide pattern, and the top surface of the grating layer is provided with a grating.

[0006] Furthermore, the grating layer material is silicon nitride.

[0007] Furthermore, a shallow etched grating is formed in the middle of the top surface of the grating layer, and side gratings are formed on both sides of the shallow etched grating. The side gratings are etched gratings that penetrate the grating layer.

[0008] Furthermore, the shallow etched grating and the side grating are staggered by less than 1 μm in the grating extension direction, and the distance between the scattering center of the shallow etched grating and the scattering center of the side grating in the waveguide thickness direction is 0-600 nm.

[0009] By controlling the offset distance between the shallow etched grating and the side grating in the extension direction and the distance in the waveguide thickness direction, the proportion of upward emission is increased, that is, the directionality of the grating is improved. Moreover, due to the double-layer structure, the effective emission length of the grating is also longer.

[0010] Furthermore, the grating layer has a thickness of 100nm-500nm.

[0011] Furthermore, the thickness of the grating layer is 400 nm.

[0012] Furthermore, the wafer layers from top to bottom are a top silicon layer, a silicon dioxide layer and a silicon substrate.

[0013] Furthermore, the wafer layer is an SOI wafer (Silicon On Insulator).

[0014] Furthermore, a silicon dioxide layer is provided between the wafer layer and the grating layer.

[0015] Furthermore, the thickness of the silicon dioxide layer is 0-500 nm.

[0016] Furthermore, the thickness of the silicon dioxide layer is 150 nm.

[0017] Furthermore, an upper cladding layer is provided above the grating layer.

[0018] A method for preparing a highly directional waveguide grating antenna is provided, and the waveguide grating antenna is prepared.

[0019] Further, the method comprises the following steps: S1. preparing a waveguide pattern on a wafer layer;

[0020] S2. Depositing a SiO2 layer and polishing the SiO2 layer;

[0021] S3. Depositing a grating layer of a certain thickness;

[0022] S4. Etching the grating layer to form an etched grating;

[0023] S5. Deposit the upper cladding layer.

[0024] Furthermore, in step S4, the grating layer is etched to form a top shallow etched grating, and the side etched grating is etched to the etching depth of the shallow etched grating at the same time, the middle shallow etched grating is retained, and the etched gratings on both sides are further etched until the grating layer in this direction is completely etched to form side gratings.

[0025] Furthermore, in step S4, the grating layer is etched to form a top shallow etched grating, the middle shallow etched grating is retained, and the gratings on both sides of the shallow etched grating are further etched until the grating layer in that direction is completely etched to form side gratings.

[0026] Furthermore, the deposition method is LPCVD (Low Pressure Chemical Vapor Deposition) or PECVD (Plasma Enhanced Chemical Vapor Deposition).

[0027] Furthermore, the polishing method is CMP (Chemical Mechanical Polishing).

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The side-etched grating is used as one of the two superimposed gratings. While achieving high directivity and a long effective emission length, compared with the method of staggered etching of grating grooves of different depths and forming grating patterns on the upper and lower surfaces of the waveguide and staggered in the grating extension direction, it can save a layer of mask and reduce manufacturing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only represent some embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0031] FIG1 is a schematic diagram of the structure of a waveguide grating antenna according to the present invention.

[0032] FIG2 is a schematic diagram of the preparation process of the waveguide grating antenna according to Example 1 of the present invention.

[0033] FIG3 is a schematic diagram of the preparation process of the waveguide grating antenna according to Example 2 of the present invention.

[0034] In the figure: 1-grating layer, 2-waveguide pattern, 3-shallow etched grating, 4-side grating. 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 are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0036] Example 1

[0037] A highly directional waveguide grating antenna, as shown in FIG1, comprises an upper layer and a lower layer, wherein the lower layer is a wafer layer, and the upper layer is a grating layer 1. The top surface of the wafer layer is provided with a waveguide pattern 2, and the top surface of the grating layer 1 is provided with a grating. The grating layer 1 is made of silicon nitride. A shallow etched grating 3 is provided in the middle of the top surface of the grating layer 1. The shallow etched grating 3 is flanked by side gratings 4. The side gratings 4 are etched gratings that penetrate the grating layer 1. The shallow etched grating 3 and the side gratings 4 are etched gratings that penetrate the grating layer 1. The staggered distance in the grating extension direction is less than 1 μm, the distance between the scattering center of the shallow etched grating 3 and the scattering center of the side grating 4 in the waveguide thickness direction is 0-600 nm, the thickness of the grating layer 1 is 100 nm-500 nm, and preferably the thickness of the grating layer 1 is 400 nm. The wafer layers are, from top to bottom, a top silicon layer, a silicon dioxide layer and a silicon substrate. A silicon dioxide layer is provided between the wafer layer and the grating layer 1, and an upper cladding layer is provided on the grating layer 1.

[0038] A method for preparing a highly directional waveguide grating antenna, as shown in Figures 1 and 2, uses an SOI wafer and is based on processes such as photolithography, etching, and material deposition. The main process flow is as follows:

[0039] Step 1: First, a waveguide pattern 2 is formed on the top silicon layer of the SOI wafer by photolithography and etching.

[0040] Step 2: Deposit SiO2 on the SOI wafer using PECVD and polish the SiO2 to 150nm using CMP.

[0041] Step 3: Use LPCVD to deposit 400nm thick Si3N4 on the polished SiO2 surface.

[0042] Step 4: Then, the silicon nitride is etched to form a top shallow-etched grating 3, and then photoetched again to form a side grating 4 to obtain a grating layer 1.

[0043] Step 5: Use PECVD to deposit a layer of SiO2, and then CMP to form the upper cladding layer of the entire device.

[0044] Example 2

[0045] A highly directional waveguide grating antenna, as shown in FIG1, comprises an upper layer and a lower layer, wherein the lower layer is a wafer layer, and the upper layer is a grating layer 1. The top surface of the wafer layer is provided with a waveguide pattern 2, and the top surface of the grating layer 1 is provided with a grating. The grating layer 1 is made of silicon nitride. A shallow etched grating 3 is provided in the middle of the top surface of the grating layer 1. The shallow etched grating 3 is flanked by side gratings 4. The side gratings 4 are etched gratings that penetrate the grating layer 1. The shallow etched grating 3 and the side gratings 4 are etched gratings that penetrate the grating layer 1. The staggered distance in the grating extension direction is less than 1 μm, the distance between the scattering center of the shallow etched grating 3 and the scattering center of the side grating 4 in the waveguide thickness direction is 0-600 nm, the thickness of the grating layer 1 is 100 nm-500 nm, and preferably the thickness of the grating layer 1 is 400 nm. The wafer layers are, from top to bottom, a top silicon layer, a silicon dioxide layer and a silicon substrate. A silicon dioxide layer is provided between the wafer layer and the grating layer 1, and an upper cladding layer is provided on the grating layer 1.

[0046] A method for preparing a highly directional waveguide grating antenna, as shown in Figures 1 and 3, uses an SOI wafer and is based on processes such as photolithography, etching, and material deposition. The main process flow is as follows:

[0047] Step 1: First, a waveguide pattern 2 is formed on the top silicon layer of the SOI wafer by photolithography and etching.

[0048] Step 2: Deposit SiO2 on the SOI wafer using PECVD and polish the SiO2 to 150nm using CMP.

[0049] Step 3: Use PECVD to deposit 400nm thick Si3N4 on the SiO2 surface after polishing in the previous step.

[0050] Step 4: Then etch the silicon nitride to form the top shallow etched grating 3, and at the same time etch the side etched grating to the etching depth of the shallow etched grating 3, protect the shallow etched grating 3 and continue to etch the side etched grating until the silicon nitride layer is completely etched to form the side grating 4, and obtain the grating layer 1.

[0051] Step 5: Use PECVD to deposit a layer of SiO2, and then CMP to form the upper cladding layer of the entire device.

[0052] The above are the implementation methods listed in this embodiment, but this embodiment is not limited to the above optional implementation methods. Those skilled in the art can arbitrarily combine the above methods to obtain other various implementation methods. Anyone can derive other various forms of implementation methods based on the inspiration of this embodiment. The above specific implementation methods should not be understood as limiting the scope of protection of this embodiment. The scope of protection of this embodiment shall be based on the definition in the claims, and the description can be used to interpret the claims.

Claims

1. A highly directional waveguide grating antenna, characterized in that: The invention comprises an upper layer and a lower layer, wherein the lower layer is a wafer layer, and the upper layer is a grating layer (1). A waveguide pattern (2) is arranged on the top surface of the wafer layer, and a grating is arranged on the top surface of the grating layer (1). A shallow etched grating (3) is arranged in the middle of the top surface of the grating layer (1), and side gratings (4) are arranged on both sides of the shallow etched grating (3). The side gratings (4) are etched gratings that penetrate the grating layer. The shallow etched grating (3) and the side gratings (4) are staggered by less than 1 μm in the grating extension direction, and the distance between the scattering center of the shallow etched grating (3) and the scattering center of the side grating (4) in the waveguide thickness direction is 0-600 nm.

2. A highly directional waveguide grating antenna according to claim 1, characterized in that: The material of the grating layer (1) is silicon nitride.

3. A highly directional waveguide grating antenna according to claim 1, characterized in that: The thickness of the grating layer (1) is 100nm-500nm.

4. A highly directional waveguide grating antenna according to claim 1, characterized in that: A silicon dioxide layer is arranged between the wafer layer and the grating layer (1).

5. A highly directional waveguide grating antenna according to claim 4, characterized in that: The thickness of the silicon dioxide layer is 0-500 nm.

6. A highly directional waveguide grating antenna according to claim 1, characterized in that: An upper cladding layer is arranged above the grating layer (1).

7. A method for preparing a highly directional waveguide grating antenna, characterized in that: A highly directional waveguide grating antenna as described in any one of claims 1 to 6 is prepared.

8. The method for preparing a highly directional waveguide grating antenna according to claim 7, characterized in that: The following steps are involved: S1. Preparing a waveguide pattern on a wafer layer; S2. Depositing a SiO2 layer and polishing the SiO2 layer; S3. depositing a grating layer of a certain thickness; S4. Etching the grating layer to form an etched grating; S5. Depositing the upper cladding layer.

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