CN1312328C - Methd for preparing monocrystalline silicon nano membrane for nano photon technique - Google Patents

Abstract

The present invention discloses a method for preparing a monocrystalline silicon nano membrane for nano photon technology. After an upper silicon chip and a substrate slice of an insulator with the thickness from hundreds of to a plurality of nanometers are cleaned and dried, the side of the silicon of the top layer of the upper silicon chip of the insulator and the substrate slice are bonded, and the substratum silicon of the upper silicon chip of the bonded insulator is removed to obtain a monocrystalline silicon nano membrane. The thickness of the monocrystalline silicon layer of the silicon nanometer membrane material prepared by the present invention can be from a plurality of nanometers to hundreds of nanometers with high thickness uniformity. The lower limiting layer of the material has sufficient thickness for realizing optical isolation, and the development of a silicon photon device with the size in a nanometer grade can be carried out. The bonding surface of the upper silicon chip and the substrate slice of the insulator can be preprocessed, provided with electrodes, realize specific patterns, etc., according to the requirements in the actual device manufacturing process.

Description

Preparation method of single crystal silicon nanofilm for nanophotonic technology

technical field

The invention relates to a preparation method of nanometer materials, in particular to a preparation method of a single crystal silicon nanofilm used in nanophoton technology.

Background technique

Nanophotonic technology based on silicon materials is an important technical means to realize high-density photonic integration and high-speed optical interconnection. The preparation of silicon nanophotonic materials is the basis for silicon nanophotonic technology research. The basic idea of preparing silicon nanophotonic materials includes bottom-up method and top-down method. The bottom-up method mainly uses the method of chemical growth to prepare silicon-based nanophotonic materials including silicon nanowires, silicon nanobelts and silicon nanotubes. Although this is an important development direction, at present, from nanophotonics From the perspective of technical requirements, these silicon nanophotonic materials are far from being able to be used in the research and development of actual devices and modularization in terms of optical transmission characteristics, structural dimensions, and device processing methods. The top-down method is the mainstream technical means of mass production at present, mainly using the developed micro-fabrication means. The material currently used in the research of silicon nanophotonic technology is mainly silicon-on-insulator (SOI: Silicon-on-Insulator) material. Although silicon-on-insulator materials based on Smart Cut technology can be used in the research of silicon nanophotonic devices to a certain extent, due to the limited thickness of the oxide isolation layer in silicon-on-insulator materials, the size of silicon nanowires is limited. When the silicon layer is extremely thin, the optical isolation effect cannot be guaranteed. In order to eliminate the limitation of silicon nanophoton technology research by the limited thickness of the oxidation isolation layer of the silicon material on the insulator, the present invention proposes a method for preparing a single crystal silicon nano film by using silicon bonding and selective self-stop etching on the insulator.

Contents of the invention

The object of the present invention is to provide a method for preparing a single-crystal silicon nanofilm for nanophotonic technology, and the prepared single-crystal silicon nanofilm can be used for research on silicon nanophotonic technology.

The technical solution adopted by the present invention to solve its technical problems is to adopt the steps as follows:

1) cleaning and drying the silicon-on-insulator wafer and the substrate wafer having a thickness of 50-200nm;

2) bonding the top silicon side of the silicon-on-insulator wafer to the substrate wafer;

3) Removing the underlying silicon of the bonded silicon-on-insulator wafer.

The substrate used is a polished bulk material with at least one side of the material whose refractive index is lower than that of the silicon material, and the polished surface is bonded to the silicon wafer on the insulator during bonding; The thickness of the film is greater than the thickness required for optical isolation. When bonding, one side of the film is bonded to the silicon on the insulator.

The substrate used is a glass plate with at least one side polished, or a quartz plate with at least one side polished, or a lithium niobate plate with at least one side polished, or a silicon plate with a silicon oxide layer, or a silicon plate with silicon nitride. sheet, or a silicon sheet with silicon oxynitride.

The top layer of silicon on the silicon-on-insulator wafer used has a thin film material with a refractive index lower than that of the silicon material, and the thickness of the film is greater than the thickness required for optical isolation; the substrate used is a bulk material with at least one side polished, or has a Silicon film material.

There is a layer of silicon dioxide film, or silicon nitride film, or silicon oxynitride film on the top silicon of the silicon-on-insulator wafer used; the substrate wafer used is a silicon wafer with at least one side polished, or a glass wafer with at least one side polished, or A quartz plate with at least one side polished.

The bonding method adopted is electrostatic bonding, the bonding temperature is 200-600°C, and the bonding voltage is 50-1500 volts; or, the bonding method adopted is thermal bonding, and the bonding temperature is 200-1000°C.

The method of removing the underlying silicon of the silicon wafer on the insulator is dry etching, or wet etching, or a combination method combined with grinding and polishing, and then dry etching or wet etching; compared with silicon dioxide materials, etching is required Or the etch process is selective to silicon.

After performing step 3), dry etching, or wet etching, or a combination of grinding and polishing, dry etching or wet etching is used to remove the oxide isolation layer of the silicon wafer on the insulator; relative to the silicon material , requiring the etch or etch process to be selective to silicon dioxide.

Before performing the bonding in step 2), the silicon on the top layer of the silicon-on-insulator is thinned by oxidation, and the thinned thickness is determined by the required nanometer film thickness.

Before performing the bonding in step 2), pretreatment is performed on the side of the bonding surface of the silicon-on-insulator wafer and the substrate wafer, metal electrodes are fabricated, and the structure is etched.

The beneficial effects that the present invention has are:

1. The optical confinement layer of the silicon nanofilm material prepared by the present invention has sufficient thickness to realize optical isolation, and can carry out the development of nanometer-sized silicon photonic devices, which cannot be guaranteed by the intermediate oxide layer of silicon wafer materials on ordinary insulators ;

2. The thickness of the monocrystalline silicon layer of the silicon nano-film material prepared by the present invention can be from tens of nanometers to hundreds of nanometers, and the thickness uniformity is high;

3. By adopting the preparation process of the present invention, according to the needs in the actual device manufacturing process, pretreatment can be carried out on the bonding surface of the silicon chip on the insulator and the substrate material, electrodes are arranged, and specific patterns are realized. This is directly using the insulator What cannot be done on silicon wafer materials.

Detailed ways

Embodiment 1: A silicon-on-insulator wafer with a 200 nm thick top layer of silicon is used, and a silicon wafer with a 15 μm thick silicon dioxide layer is used as a substrate, which is cleaned and dried after conventional cleaning. Stack the top layer silicon of the silicon-on-insulator wafer and the silicon dioxide layer of the silicon wafer facing each other, place them on a bonding machine for thermal bonding, and the bonding temperature is between 800°C. After bonding, put the bonded chips into a 40% potassium hydroxide solution for wet etching to etch the underlying silicon of the silicon chip on the insulator. The chip is further put into a hydrofluoric acid solution for wet etching to remove the oxide isolation layer of the silicon chip on the insulator. Finally, a silicon nano-film material with a silicon substrate, an optical isolation layer with a thickness of 15 μm of silicon dioxide, and a silicon film of about 200 nm can be prepared.

Embodiment 2: A silicon-on-insulator wafer with 100nm top layer of silicon is used, and a glass wafer is used as the substrate, which is cleaned and dried after conventional cleaning. Stack the top layer of silicon on the silicon-on-insulator wafer and the polished surface of the glass wafer, and place them on an electrostatic bonding machine for electrostatic bonding. The bonding temperature is between 300°C and the bonding voltage is 900 volts. After bonding, the silicon-on-insulator (SOI) side of the bonded wafers is placed upwards, placed in a dry etching device, and the underlying silicon of the silicon-on-insulator wafers is etched away by dry etching. Thus, a silicon nano-membrane material with a silicon film of about 100 nm is prepared, which uses glass as a substrate, and has a silicon dioxide layer as an upper limiting layer on the top layer.

Embodiment 3: A silicon-on-insulator wafer with a 50nm top layer of silicon is used, and the silicon wafer is used as the substrate, and is dried after conventional cleaning. First grow a silicon nitride layer with a thickness of 15 μm on the silicon-on-insulator wafer, then stack the grown silicon-on-insulator wafer and the polished surface of the silicon wafer opposite each other, and place them on a bonding machine for thermal bonding. The bonding temperature is 900°C between. After bonding, use a combined method to first grind and polish the silicon side of the bonded sheet insulator. When the thickness of the silicon layer is 50-100 μm, put it into a 40% concentration of potassium hydroxide solution for wet etching to etch away The underlying silicon of a silicon-on-insulator wafer. Thus, a silicon nano-membrane material with silicon as the substrate, an optical isolation layer with a thickness of 15 μm silicon nitride layer, a silicon dioxide layer as the upper limiting layer on the top layer, and a silicon film of about 50 nm is prepared.

Embodiment 4: A silicon-on-insulator wafer with a top silicon layer of 200 nm is used, and a glass wafer is used as a substrate, which is cleaned and dried after conventional cleaning. First, the silicon-on-insulator wafer is oxidized by wet oxygen, and about 250nm of silicon dioxide is oxidized on the surface, and the top layer of silicon under this silicon dioxide layer will be about 100nm. Then the top layer of silicon on the silicon wafer on the insulator and the polished surface of the glass wafer are superimposed and placed on an electrostatic bonding machine for electrostatic bonding. The bonding temperature is between 500°C and the bonding voltage is 1200 volts. After bonding, grind and polish the silicon-on-insulator side of the bonded sheet. When the thickness of the silicon layer is 50-100 μm, place the silicon-on-insulator side of the bonded sheet facing up and place it in a dry etching device. The underlying silicon of the silicon-on-insulator wafer is etched away by dry etching. Thus, a silicon nano-membrane material with a silicon film of about 100 nm is prepared, which uses glass as a substrate, and has a silicon dioxide layer as an upper limiting layer on the top layer.

Embodiment 5: A silicon-on-insulator wafer with a 200 nm top layer of silicon is used, and a quartz wafer is used as a substrate, and is dried after conventional cleaning. Photolithography and etching were carried out on the surface of the silicon wafer on insulator to produce silicon nanometer straight lines with a width of 200 nm. Then stack the top layer silicon of the silicon-on-insulator wafer and the polished surface of the quartz wafer, and place them on a bonding machine for thermal bonding at a bonding temperature of 700°C. After bonding, put the bonded chips into a 40% potassium hydroxide solution for wet etching to etch the underlying silicon of the silicon chip on the insulator. The chip is further put into a hydrofluoric acid solution for wet etching to remove the oxide isolation layer of the silicon chip on the insulator. Thus, a silicon nano-film material with a thickness of about 200nm and a width of 200nm is prepared using quartz as a substrate.

There are multiple implementations of the present invention, above enumerated 5 embodiments, are used for explaining the present invention, but are not limited to these 5 embodiments by no means, rather than limit the present invention, in the spirit of the present invention and claims Within the protection scope of the present invention, any modifications and changes made to the present invention fall within the protection scope of the present invention.

Claims (10)

1. preparation method who is used for the silicon single crystal nanometer film of nano-photon technology is characterized in that the step that adopts is as follows:

1) SOI and the substrate slice that will have 50～200nm thickness cleans the back oven dry;

2) top layer silicon one side and the substrate slice with SOI carries out bonding;

3) the bottom silicon of the SOI behind the removal bonding.

2. a kind of preparation method who is used for the silicon single crystal nanometer film of nano-photon technology according to claim 1, it is characterized in that: the substrate slice of employing is the body material of specific refractory power less than at least one mirror polish of silicon materials, and polished surface and SOI carry out bonding during bonding; Perhaps, the substrate slice of employing is for to have the material of one deck specific refractory power less than the film of silicon materials at least, and the thickness of film is isolated desired thickness greater than light, and film one side and SOI carry out bonding during bonding.

3. a kind of preparation method who is used for the silicon single crystal nanometer film of nano-photon technology according to claim 2, it is characterized in that: the substrate slice of employing is the sheet glass of at least one mirror polish, it perhaps is the quartz plate of at least one mirror polish, it perhaps is the Lithium niobium trioxide sheet of at least one mirror polish, perhaps for having the silicon chip of silicon oxide layer, perhaps for having the silicon chip of silicon nitride, perhaps for having the silicon chip of silicon oxynitride.

4. a kind of preparation method who is used for the silicon single crystal nanometer film of nano-photon technology according to claim 1, it is characterized in that: the thin-film material of one deck specific refractory power less than the silicon materials specific refractory power arranged on the top layer silicon of the SOI of employing, and the thickness of film is isolated desired thickness greater than light; The substrate slice that adopts is the body material of at least one mirror polish, perhaps has the material of silicon-dioxide layer film.

5. a kind of preparation method who is used for the silicon single crystal nanometer film of nano-photon technology according to claim 4 is characterized in that: the layer of silicon dioxide film is arranged, perhaps silicon nitride film, perhaps silicon oxynitride film on the top layer silicon of the SOI of employing; The substrate slice that adopts is the silicon chip of at least one mirror polish, perhaps the sheet glass of at least one mirror polish, the perhaps quartz plate of at least one mirror polish.

6. a kind of preparation method who is used for the silicon single crystal nanometer film of nano-photon technology according to claim 1, it is characterized in that: the bonding method of employing is an electrostatic bonding, and bonding temperature is 200-600 ℃, and bonding voltage is the 50-1500 volt; Perhaps, the bonding method of employing is a thermal bonding, and bonding temperature is 200-1000 ℃.

7. a kind of preparation method who is used for the silicon single crystal nanometer film of nano-photon technology according to claim 1, it is characterized in that: the method for removing the bottom silicon of SOI is a dry etching, perhaps wet etching, or in conjunction with grinding and polishing, the combined method of dry etching or wet etching again.

8. a kind of preparation method who is used for the silicon single crystal nanometer film of nano-photon technology according to claim 1, it is characterized in that: after carrying out step 3), adopt dry etching, perhaps wet etching, or in conjunction with grinding and polishing, the combined method of dry etching or wet etching is removed the oxidation sealing coat of SOI again.

9. a kind of preparation method who is used for the silicon single crystal nanometer film of nano-photon technology according to claim 1, it is characterized in that: carry out step 2) bonding before, adopt the method for oxidation that the top layer silicon of silicon-on-insulator is carried out attenuate, the one-tenth-value thickness 1/10 of attenuate is determined by needed nanometer film thickness.

10. a kind of preparation method who is used for the silicon single crystal nanometer film of nano-photon technology according to claim 1, it is characterized in that: carry out step 2) bonding before, bonding face one side to SOI and substrate slice is carried out pre-treatment, makes metal electrode, etching structure.