阅读说明：本技术 一种玻璃基悬浮脊形硅波导的制备方法 (Preparation method of glass-based suspended ridge silicon waveguide ) 是由 尚金堂 汪子及 于 2020-04-21 设计创作，主要内容包括：本发明公开一种玻璃基悬浮脊形硅波导的制备方法,包括如下步骤：步骤1,制备带沟道的玻璃基底；步骤2,通过阳极键合工艺在玻璃基底上形成硅器件层；步骤3,在硅器件层上旋涂光刻胶,并进行光刻,在硅器件层上留下与波导脊形图案一致的条形光刻胶,再进行干法刻蚀,得到脊形硅波导芯层。此种方法可有效增强悬浮脊形硅波导芯层的结构强度及稳定性。(The invention discloses a preparation method of a glass-based suspended ridge silicon waveguide, which comprises the following steps: step 1, preparing a glass substrate with a channel; step 2, forming a silicon device layer on the glass substrate through an anodic bonding process; and 3, spin-coating photoresist on the silicon device layer, carrying out photoetching, leaving strip-shaped photoresist consistent with the waveguide ridge pattern on the silicon device layer, and carrying out dry etching to obtain the ridge silicon waveguide core layer. The method can effectively enhance the structural strength and stability of the suspended ridge-shaped silicon waveguide core layer.)

1. A preparation method of a glass-based suspended ridge silicon waveguide is characterized by comprising the following steps:

step 1, preparing a glass substrate with a channel;

step 2, forming a silicon device layer on the glass substrate through an anodic bonding process;

and 3, spin-coating photoresist on the silicon device layer, carrying out photoetching, leaving strip-shaped photoresist consistent with the waveguide ridge pattern on the silicon device layer, and carrying out dry etching to obtain the ridge silicon waveguide core layer.

2. The method of manufacturing a glass-based suspended ridge silicon waveguide according to claim 1, wherein: in the step 1, a channel is formed on the glass wafer by adopting a mechanical etching, dry etching or wet etching mode, so as to obtain the glass substrate with the channel.

3. The method of manufacturing a glass-based suspended ridge silicon waveguide according to claim 1, wherein: the wet etching method is to perform wet etching on the glass wafer with the mask layer through 49% HF solution and remove the mask layer to obtain a channel consistent with the path of the ridge-shaped silicon waveguide.

4. The method of manufacturing a glass-based suspended ridge silicon waveguide according to claim 1, wherein: the thickness of the glass substrate is 1-2000 μm, the depth of the channel is 1-50 μm, and the width is 1-50 μm.

5. The method of manufacturing a glass-based suspended ridge silicon waveguide according to claim 1, wherein: the glass substrate is made of glass which is provided with conductive ions and can be subjected to anodic bonding.

6. The method of manufacturing a glass-based suspended ridge silicon waveguide according to claim 5, wherein: the glass substrate is made of borosilicate glass.

7. The method of manufacturing a glass-based suspended ridge silicon waveguide according to claim 1, wherein: the specific process of the step 2 is as follows:

step 211, enabling the monocrystalline silicon wafer to be opposite to one surface with the channel on the glass substrate, and carrying out anodic bonding on the glass substrate and the monocrystalline silicon wafer;

step 212, the bonded silicon portion is thinned and polished to obtain a silicon device layer.

8. The method of manufacturing a glass-based suspended ridge silicon waveguide according to claim 1, wherein: the specific process of the step 2 is as follows:

step 221, enabling the SOI wafer silicon device layer to be opposite to one surface with the channel on the glass substrate, and carrying out anodic bonding on the glass substrate and the silicon wafer;

and step 222, removing the bonded silicon substrate by wet etching with 25% TMAH solution, removing the oxide layer by wet etching or dry etching, and cleaning.

Technical Field

The invention belongs to the technical field of optical communication and optical sensing, particularly relates to a planar integrated optical waveguide and a preparation technology thereof, and particularly relates to a preparation method of a glass-based suspended ridge silicon waveguide.

Background

Because the medium infrared band contains the strong absorption peak of most chemical bonds, even a fingerprint window, the medium infrared band becomes a 'gold band' for biological and chemical substance and molecule detection. Meanwhile, in recent years, the continuous development of planar optical waveguides and integrated photoelectric technologies enables the chip-level optical sensor with low cost to be expected to replace the traditional biochemical molecule detection equipment with huge volume, and the low-cost, high-sensitivity and portable detection of biochemical molecules is realized. The reported optical sensor based on the mid-infrared planar optical waveguide can detect various chemical and biological substances such as methane, carbon dioxide, heavy water, ethanol, phenethylamine, toluidine and the like.

The planar optical waveguide is used as a core device of the mid-infrared light sensor, and the detection performance of the optical sensor is directly determined by parameters such as the width of a transparent waveband, the optical transmission loss in a target mid-infrared waveband, the physical and chemical stability and the like. Since silica has strong absorption loss to light in the mid-infrared band of 3.5 μm or more, the optical waveguide schemes using silica as the waveguide outer cladding, such as commercial silica-based silica-on-silicon (SOS) waveguide and SOI-based single-mode silicon waveguide which has become a main research focus in recent years, cannot meet the transmission requirement of mid-infrared optical signals. In order to solve the problem, various novel mid-infrared waveguide architectures such as chalcogenide glass optical waveguides, germanium-silicon waveguides, suspended ridge-shaped silicon waveguides and the like having a wide transmission spectrum in the mid-infrared band are proposed in succession. The suspended silicon waveguide has the advantages of low transmission loss of the ridge waveguide, wide band transparent window, compatibility with a standard CMOS (complementary metal oxide semiconductor) process and the like, and the upper part and the lower part of a waveguide core layer can be simultaneously contacted with detected gas or solution to increase the contact area, so that the detection sensitivity of the mid-infrared light waveguide sensor based on the type can be effectively improved.

The existing preparation of the suspended silicon waveguide mainly utilizes partial etching and opening of the outside of a silicon device layer with a ridge waveguide structure etched on the top layer on an SOI wafer to form a plurality of channels leading to a silicon dioxide layer, and then utilizes wet etching to etch off the silicon dioxide on the lower part of a silicon waveguide core layer, thereby forming the suspended silicon waveguide capable of working in the middle infrared. However, the punching and etching of the two sides of the silicon waveguide core layer which plays a supporting role can reduce the structural strength of the ridge silicon waveguide and reduce the yield and the overall performance of the silicon waveguide; meanwhile, in order to ensure that the optical signal is not leaked in the silicon substrate of the SOI wafer, the ridge silicon waveguide based on the SOI needs a thicker oxide layer as a sacrificial layer in the preparation process, and the production cost is increased.

Disclosure of Invention

The invention aims to provide a preparation method of a glass-based suspended ridge silicon waveguide, which can effectively enhance the structural strength and stability of a suspended ridge silicon waveguide core layer.

In order to achieve the above purpose, the solution of the invention is:

a preparation method of a glass-based suspended ridge silicon waveguide comprises the following steps:

step 1, preparing a glass substrate with a channel;

step 2, forming a silicon device layer on the glass substrate through an anodic bonding process;

and 3, spin-coating photoresist on the silicon device layer, carrying out photoetching, leaving strip-shaped photoresist consistent with the waveguide ridge pattern on the silicon device layer, and carrying out dry etching to obtain the ridge silicon waveguide core layer.

In the step 1, a channel is formed on the glass wafer by adopting a mechanical etching, dry etching or wet etching mode, so as to obtain the glass substrate with the channel.

The wet etching method is to perform wet etching on the glass wafer with the mask layer by 49% HF solution and remove the mask layer to obtain a channel consistent with the path of the ridge silicon waveguide.

The thickness of the glass substrate is 1 to 2000 μm, preferably 500 μm, the depth of the trench is 1 to 50 μm, preferably 10 μm, and the width is 1 to 50 μm, preferably 20 μm.

The material of the glass substrate is glass which is provided with conductive ions and can be subjected to anodic bonding, and borosilicate glass is preferable.

The specific process of the step 2 is as follows:

step 211, enabling the monocrystalline silicon wafer to be opposite to one surface with the channel on the glass substrate, and carrying out anodic bonding on the glass substrate and the monocrystalline silicon wafer;

step 212, the bonded silicon portion is thinned and polished to obtain a silicon device layer.

The specific process of the step 2 is as follows:

step 221, enabling the SOI wafer silicon device layer to be opposite to one surface with the channel on the glass substrate, and carrying out anodic bonding on the glass substrate and the silicon wafer;

and step 222, removing the bonded silicon substrate by wet etching with 25% TMAH solution, removing the oxide layer by wet etching or dry etching, and cleaning.

By adopting the scheme, the grooved glass is used as the substrate, the ridge silicon is used as the waveguide core layer, the filler in the channel is used as the lower cladding layer of the suspended ridge silicon waveguide, and the glass silicon waveguide can meet the single-mode transmission condition of near-infrared or intermediate-infrared bands by adjusting the parameters of the ridge width, the inner ridge, the outer ridge and the like of the ridge waveguide, so that the glass silicon waveguide can be applied to the fields of near-infrared and intermediate-infrared high-performance communication, sensing, biochemical detection and the like.

The invention has the following improvements:

(1) the silicon device layer is not required to be etched and opened, so that the structural strength of the silicon device layer is improved;

(2) the channel is prepared on the glass substrate without thick oxide layer SOI, thereby reducing the cost

Drawings

FIG. 1 is a three-dimensional schematic diagram of a glass-based suspended ridge silicon waveguide;

FIG. 2 is a cross-sectional view of a suspended ridge silicon waveguide;

FIG. 3 is a suspended ridge-shaped silicon waveguide TE fundamental mode optical field distribution diagram;

FIG. 4 is a suspended ridge silicon waveguide TM fundamental mode optical field distribution diagram;

FIG. 5a shows the preparation of a trench in a glass substrate;

FIG. 5b shows the bonding of a glass substrate to a single crystal silicon wafer;

FIG. 5c shows a silicon device layer obtained by a thinning, polishing process;

FIG. 5d shows a ridge silicon waveguide obtained by an etching process;

FIG. 5e shows the removal of the photoresist to obtain a glass-based suspended ridge silicon waveguide;

FIG. 6a shows the preparation of a trench in a glass substrate;

FIG. 6b shows bonding of an SOI silicon device layer to a glass substrate by anodic bonding;

FIG. 6c shows a silicon device layer obtained by a thinning, polishing process;

FIG. 6d shows a rib silicon waveguide obtained by an etching process;

fig. 6e shows the removal of the photoresist, resulting in a glass-based suspended ridge silicon waveguide.

Detailed Description

The technical solution and the advantages of the present invention will be described in detail with reference to the accompanying drawings.

The invention provides a preparation method of a glass-based suspended ridge silicon waveguide, which comprises the following steps:

step one, preparing a glass substrate 120 with a channel;

forming a silicon device layer on the glass substrate by an anodic bonding process;

step three, preparing a ridge silicon waveguide core layer 110 meeting the single-mode transmission condition through photoetching and etching processes;

as shown in fig. 1, the glass-based suspended ridge silicon waveguide prepared by the preparation method provided by the present invention comprises a suspended ridge silicon waveguide core layer 1, a ridge waveguide lower channel 2 and a glass substrate 3, wherein the ridge waveguide lower channel 2 is arranged on the glass substrate 3 and serves as a substrate of the suspended ridge silicon waveguide, and is made of glass capable of anodic bonding with conductive ions, such as BF33 glass in borosilicate glass; the suspended ridge silicon waveguide core layer 1 is arranged above a channel 2 below the ridge waveguide, the suspended ridge silicon waveguide core layer 1 is isolated from a glass substrate 3 by the channel 2 below the ridge waveguide, and when other substances are not filled in the channel, air is used as a lower cladding of the suspended ridge silicon waveguide core layer 1; the width of the channel ranges from 1 to 50 μm and the depth of the channel ranges from 1 to 50 μm. As shown in fig. 2, a cross-sectional view of a suspended ridge silicon waveguide.

The suspended ridge silicon waveguide core layer 1 is composed of a ridge silicon waveguide core layer, a lower cladding layer and an upper cladding layer, when other substances are not filled in a channel and on the upper portion of the core layer and are not in vacuum, air in the channel and on the upper portion of the silicon waveguide core layer is respectively used as the upper cladding layer and the lower cladding layer of the suspended ridge silicon waveguide core layer, and at the moment, infrared band optical signals of 1000nm-8000nm, especially middle infrared band optical signals larger than 3500nm, can be transmitted in the suspended ridge silicon waveguide core layer in a low-loss mode.