CN1102540C - Silicon photowave guide material on glass and its preparation - Google Patents

Abstract

A silicon optical waveguide material on glass and a manufacturing method thereof. The optical waveguide material is an optical waveguide material with glass as a substrate, silicon as a waveguide layer, and glass or glass silicon monoxide as a confinement layer. The manufacturing method includes: polishing a silicon wafer The silicon oxide surface of the silicon wafer with a silicon oxide layer and the polished surface of the glass wafer are routinely cleaned and then dried, the glass wafer and the silicon wafer or the silicon oxide surface of the silicon wafer are bonded, and the silicon wafer is thinned to the required thickness. The advantages of the material and its manufacturing process are: the glass substrate is directly used as the limiting layer, the limiting effect is good, there is no high-temperature process in the production, the bonding result is intuitive, and the requirements for subsequent process equipment are simplified.

Description

Silicon optical waveguide material on glass and method of making the same

The invention relates to a silicon optical waveguide material, in particular to a silicon optical waveguide material on glass and a manufacturing method thereof.

The rapid development of optical fiber communication puts forward higher and higher requirements for optoelectronic devices. In line with this, the basic theory of semiconductor optical waveguides is becoming more and more mature, and related technical problems are gradually being solved. In order to utilize silicon materials with low price and mature technology, the manufacture and application of silicon-based optical waveguides have attracted people's attention. According to the theory of optical waveguides, silicon-based optical waveguides combine silicon (waveguide layer) with other low-refractive-index materials (confinement layers), and process them into ridge-shaped waveguides with a ridge height of about 8 microns through semiconductor technology. The infrared light with a wavelength of 1.3-1.6 microns used in the above can be confined in the silicon layer and propagate in a single mode with low loss. At present, the silicon-based optical waveguide is usually made of silicon-on-insulator (SOI) material.

The so-called silicon material on the insulating layer generally refers to a material with an oxide layer on the bulk silicon and a layer of silicon on the oxide layer, which is developed and manufactured for low power consumption electronic devices. When the silicon material on the insulating layer is used as an optical waveguide material, the bulk silicon is used as the substrate, the silicon oxide is used as the confinement layer, and the silicon layer on it is the device layer (waveguide layer). At present, the commercially available silicon materials used on the insulating layer of optical waveguides mainly include silicon direct bonding type (Sillicon-Direct-Bonding, SDB) and oxygen injection isolation type (Separation-by-Implanted-Oxygen, SIMOX). . Among them, the silicon material on the silicon direct bonding insulating layer is thermally oxidized two single crystal silicon wafers, bonded together above 800 degrees Celsius, and then thinned one of the silicon wafers to the required thickness, and the other silicon wafer sheet as a substrate. The silicon material on the silicon direct bonding insulating layer has a denser oxide layer and a silicon layer with fewer defects, but as an optical waveguide material, its high temperature process limits the pre-production of optoelectronic devices, such as prefabricated electrodes. The silicon material on the oxygen-implanted isolation type insulating layer is implanted into the silicon substrate with high-energy oxygen ions (150-300 keV). The ion current density is related to the implantation energy, generally 2.6×10 ¹⁸ at 150 keV. /square centimeter, it is 1.3×10 ¹⁸ /square centimeter at 300 kiloelectron volts. After injection, the sample was annealed at 1150 degrees Celsius for 2 hours to form a silicon material on the insulating layer. The oxygen injection isolation type has better uniformity and thickness controllability. However, because the injected oxygen has a Gaussian distribution, the silicon-silicon oxide interface is blurred, and a sudden refractive index distribution cannot be obtained, which affects the confinement of the silicon oxide layer. In addition, the silicon layer on the top of the silicon material on the oxygen-implanted isolation insulating layer is relatively thin, and a layer of silicon needs to be epitaxially grown on the top. Annealing can eliminate defects and obtain a better quality epitaxial silicon layer. Generally speaking, both silicon materials on insulating layers require high-temperature processes, high process requirements, and complex equipment. In addition, both silicon-on-insulator materials have a thicker waveguide layer and a thinner confinement layer. The confinement layer of the silicon direct bonding type is on the order of microns, and the confinement layer of the oxygen injection isolation type is generally smaller than 0.5 microns. A thicker waveguide layer will not meet the single-mode working conditions; a thinner confinement layer is not conducive to the confinement of the optical field and increases the transmission loss.

The object of the present invention is to propose a silicon-on-glass waveguide material structure with glass as the confinement layer and its corresponding manufacturing method in order to overcome the above-mentioned difficulties.

The main content of the invention is: a silicon optical waveguide material on glass, which is characterized in that it uses glass as a substrate, silicon as a waveguide layer, and glass as a confinement layer. Said limiting layer is glass-silicon oxide layer; the specific production steps are as follows: (1) the polished surface of the silicon wafer and the polished surface of the glass wafer are dried after routine cleaning; (2) the silicon wafer is bonded to the Glass sheet bonding, bonding temperature 300°C-400°C, bonding voltage 800V-1600V; (3) Thinning the silicon sheet after bonding to reach the required thickness.

The production method of the silicon optical waveguide material on the glass is characterized in that its production steps are: (1) the silicon wafer is first subjected to high-temperature oxidation treatment to form a silicon wafer with a layer of silicon oxide; (2) the silicon wafer with a silicon oxide layer The silicon oxide surface of the sheet and the polished surface of the glass sheet are dried after conventional cleaning; (3) the silicon sheet with the silicon oxide layer is bonded to the glass sheet on an electrostatic bonding machine, and the bonding temperature is 300 degrees Celsius to 400 degrees Celsius. Combined voltage is 800V-1600V; (4) Thinning the silicon wafer to reach the required thickness. The method of thinning the silicon wafer can be anisotropic etchant corrosion, mechanical polishing, chemical polishing, electrochemical corrosion or a combination thereof.

The structure and process advantages of the silicon optical waveguide material on glass of the present invention are as follows:

1. The special thinning method can obtain better surface flatness on the basis of ensuring thin silicon wafer thickness, and meet the requirements of low-loss propagation of optical waveguide materials.

2. The glass substrate is directly used as the confinement layer, and the confinement effect is good. According to the optical waveguide theory, the thicker the confinement layer, the smaller the loss of the waveguide in the confinement layer. The silicon oxide confinement layer of the silicon material on the silicon direct bonding insulating layer is made by thermal oxidation method, generally within 2 microns. The silicon oxide confinement layer of the silicon material on the oxygen-implanted isolation insulating layer is formed by ion implantation, and its thickness is generally less than 0.4 microns. The confinement layer of the silicon optical waveguide material on the glass of the present invention is a glass substrate or silicon oxide and glass substrate, and the confinement layer thickness is the glass substrate thickness or the thickness of silicon oxide and glass substrate, and its thickness is generally several hundred Microns. Therefore, silicon-on-glass optical waveguide materials have a better confinement effect.

3. There is no high-temperature process in the production method. The production of silicon material on the silicon direct bonding insulating layer requires thermal oxidation and silicon-silicon bonding, and the process temperature reaches above 1000 degrees Celsius. The present invention only needs to carry out glass-silicon (silicon oxide) bonding, and the process temperature is 300-400 degrees centigrade, which is far lower than silicon-silicon bonding. Since there is no high-temperature process, metal electrodes can be prefabricated on glass and silicon to meet some special requirements. For example, when making a modulator, prefabricated electrodes can be used to increase the modulation electric field intensity at the same voltage to improve modulation efficiency.

4. The bonding result is intuitive, reducing the requirements for subsequent process equipment. Since the glass is transparent to visible light, the bonding result of the present invention is intuitive and easy to check. In the silicon-silicon bonding process, since silicon is opaque to visible light, only infrared methods can be used to observe the bonding results, which increases the difficulty of detection. In addition, due to the transparency of the glass, the subsequent double-sided overlay and other processes can be carried out on a conventional double-sided photolithography machine, and it is also easy to perform graphic registration on the bonding surface during re-bonding.

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 Schematic diagram of the structure of one of the silicon-on-glass optical waveguide materials.

Fig. 2 Schematic diagram of the second structure of the silicon-on-glass optical waveguide material.

The silicon-on-glass optical waveguide material in Figure 1 is an optical waveguide material with glass as the substrate, glass as the confinement layer, and silicon as the waveguide layer. The material in Figure 2 uses glass as the substrate and glass-silicon oxide as the confinement layer. , silicon is the optical waveguide material of the waveguide layer.

The method steps of making the above-mentioned materials are illustrated as follows by citing examples.

Embodiment 1, the glass is a silicon-on-glass optical waveguide material with a confinement layer, and the manufacturing steps are as follows:

1. Polish the silicon wafer,

2. Polish the glass sheet,

3. The polished surface of the silicon wafer and the polished surface of the glass wafer are dried after routine cleaning;

4. Bond the polished surface of the silicon wafer and the polished surface of the glass wafer on an electrostatic bonding machine, the bonding temperature is 380°C, and the bonding voltage is 1200 volts;

5. First corrode with 50% potassium hydroxide solution at 60°C, stop the corrosion when the thickness of the silicon wafer is about 40 microns, and thin the silicon wafer to the required thickness by mechanical polishing.

Embodiment 2, glass-silicon oxide as the confinement layer silicon-on-glass optical waveguide material, the production steps are as follows:

1. The silicon wafer is first subjected to high-temperature oxidation treatment to form a silicon wafer with a layer of silicon oxide;

2. The silicon oxide surface of the silicon wafer with silicon oxide and the polished surface of the glass wafer are dried after routine cleaning;

3. Bond the silicon wafer with silicon oxide to the glass wafer on the electrostatic bonding machine, the bonding temperature is 400°C, and the bonding voltage is 1200 volts;

4. After bonding, use 50% potassium hydroxide solution to etch at 60°C, stop the corrosion when the thickness of the silicon wafer is about 40 microns, and use mechanical polishing to thin the silicon wafer to the required thickness.

Claims (5)

1. A silicon optical waveguide material on glass, characterized in that it is an optical waveguide material with glass as a substrate, silicon as a waveguide layer, and glass as a confinement layer. 2. The silicon-on-glass optical waveguide material according to claim 1, characterized in that said confinement layer is a glass-silicon oxide layer. 3. The manufacturing method of silicon optical waveguide material on glass according to claim 1, characterized in that the specific manufacturing steps are as follows: (1) The polished surface of the silicon wafer and the polished surface of the glass wafer are dried after routine cleaning; (2) Bond the silicon wafer and the glass wafer on an electrostatic bonding machine, the bonding temperature is 300 degrees Celsius to 400 degrees Celsius, and the bonding voltage is 800 volts to 1600 volts; (3) Thinning the silicon wafer after bonding to achieve the required thickness. 4. The manufacturing method of silicon optical waveguide material on glass according to claim 2, characterized in that its manufacturing steps are: (1) The silicon wafer is first subjected to high-temperature oxidation treatment to form a silicon wafer with a layer of silicon oxide; (2) the silicon oxide surface and the polished glass surface of the silicon wafer having a silicon oxide layer are dried after routine cleaning; (3) Bonding the silicon wafer with the silicon oxide layer to the glass wafer on the electrostatic bonding machine, the bonding temperature is 300 degrees Celsius-400 degrees Celsius, and the bonding voltage is 800 volts-1600 volts; (4) Thinning the silicon wafer to achieve the desired thickness. 5. The manufacturing method of silicon optical waveguide material on glass according to claim 3 or 4, characterized in that said silicon wafer is treated by thinning method, which can be anisotropic etchant corrosion or mechanical polishing , or chemical polishing, or electrochemical corrosion or a combination thereof.

Images