CN103064147A

CN103064147A - Method for manufacturing optical waveguide on the basis of focused ion beam lithography

Info

Publication number: CN103064147A
Application number: CN2013100383659A
Authority: CN
Inventors: 杨琳娟; 姜潇潇; 谷琼婵; 宋爱娟; 梁丽勤; 吕江涛; 王凤文; 司光远
Original assignee: Northeastern University Qinhuangdao Branch
Current assignee: Northeastern University Qinhuangdao Branch
Priority date: 2013-01-31
Filing date: 2013-01-31
Publication date: 2013-04-24
Anticipated expiration: 2033-01-31
Also published as: CN103064147B; WO2014117674A1

Abstract

The invention provides a method for manufacturing an optical waveguide on the basis of focused ion beam lithography. The method comprises the following steps of: S1. designing a nanometer ring array structure, wherein nanometer rings of the nanometer ring array structure are mutually closely attached, and the lithography width value of the optical waveguide is twice larger than that of the widths of the nanometer rings; S2. saving the nanometer ring array structure into a focused ion beam lithography system; and S3. calling the nanometer ring array structure from the focused ion beam lithography system, and carrying out lithography on the surface of a focused ion beam bombarding sample to complete preparation. The optical waveguide structure manufactured through the method provided by the invention has the advantages of superhigh duty ratio and almost vertical side wall.

Description

Method based on the focused-ion-beam lithography optical waveguide

Technical field

The present invention relates to field of optical device technology, be specifically related to a kind of method based on the focused-ion-beam lithography optical waveguide.

Background technology

Optical waveguide is widely used in preparing in all kinds of optical device, and the experiment of optical waveguide preparation mainly contains wet etching and two kinds of methods of dry etching.Wherein wet etching is to have corrosive acid solution by use the material for the preparation of optical waveguide is carried out etching and final formation waveguide.Its preparation principle blocks by using mask as shown in Figure 1, so that acid solution only partly carries out etching to being exposed to outer sample, and the part that is blocked then can not be etched (annotate: being used as the material that mask uses needs antiacid corrosion).By this selective etch, finally form needed optical waveguide structure just.Wet etching is because the reaction of the material that need be etched and acid solution is subject to the impact of factors, so that etching process is difficult for being controlled.Such as, the speed of reaction and the solubility of solution, temperature and pressure are in close relations.In etching process, must guarantee various stable, the ripple disables of factor that affect reaction rate, otherwise can cause the as a result heterogeneity of etching.Produce excessive loss when this inhomogenous waveguide shapes can cause light to transmit therein, reduce the work efficiency of device, the usable range of restriction device.

For dry etching, the most frequently used method is plasma etching (plasma etching).Compared to wet etching, this method etch rate is on the low side, but but can reach good control to etching process.In addition, for the sidewall of optical waveguide, its vertical extent can obtain improvement to a certain degree.But, (dutycycle is English to be aspect ratio to use the plasma etching method still can't obtain very large etching depth and very high dutycycle, be defined as etching depth/etching width), although this is that the incident direction during the Ions Bombardment sample is not all fully perpendicular to sample surfaces because ion can be to bombard sample surfaces at a high speed under the effect of accelerating field.Shown in the synoptic diagram among Fig. 2, that is to say, thereby being angle bombardment sample surfaces and the removing substances that tilts certain, most of ion forms waveguide.No matter as seen be to use wet etching or use plasma etching, an inevitable problem is arranged, that is exactly the uneven and out of plumb of sidewall of prepared waveguide, the structure that all is difficult to obtain large-sized etching depth He has the superelevation dutycycle.

Summary of the invention

(1) technical matters to be solved

For solving the problems of the technologies described above, the invention provides a kind of optical waveguide preparation method based on focused-ion-beam lithography, obtain having the superelevation dutycycle of deep etching and the optical waveguide structure of vertical sidewall almost completely.

(2) technical scheme

The invention provides a kind of method based on the focused-ion-beam lithography optical waveguide, the method comprises:

S1, a kind of nanometer circle ring array structure of design, the nanometer annulus is close to mutually in the described nanometer circle ring array structure, and the etching width value of optical waveguide is the annulus width of twice;

S2, described nanometer circle ring array structure is saved in the focused-ion-beam lithography system;

S3, call described nanometer circle ring array structure from focused ion beam system, focused ion beam is vertically bombarded sample surfaces and is carried out etching, finishes preparation.

Wherein, the etching width minimum value of described optical waveguide is 20nm.

(3) beneficial effect

The present invention adopts the nano-rings structure of being close to mutually to carry out focused-ion-beam lithography, the waveguide of superelevation duty ratio optical has almost vertical side wall construction, the waveguide and the optical device that are comprised of this structure have ultralow loss, can be so that the serviceability of device is greatly improved.Corresponding range of application also can significantly be expanded, and the device that obtains is superior performance, stable not only, and can reproduce exactly the light signal that institute transmits and preserves.

Description of drawings

Fig. 1 is the principle of work synoptic diagram of wet etching;

Fig. 2 is the principle of work synoptic diagram of plasma etching method;

Fig. 3 is focused-ion-beam lithography method principle of work synoptic diagram;

Fig. 4 is compact circle ring array structure;

Fig. 5 is preparation method's flow chart of steps of the present invention;

Fig. 6 is the cross section scanning electron microscope diagram of superelevation duty ratio optical waveguiding structure;

Fig. 7 is for using the focused-ion-beam lithography legal effect comparison diagram that uses circular ring structure among traditional wet method/plasma etching method and the present invention;

The complicated rhombus optical waveguide that Fig. 8 prepares for the method for using the present invention's proposition.

Embodiment

Below in conjunction with the drawings and specific embodiments the present invention is described in further details.

The present invention uses focused ion beam (focused ion beam, note by abridging be FIB) lithographic method, and its principle of work synoptic diagram as shown in Figure 3.Be focused onto the surface of sample through the gallium ion behind the electric field acceleration by a pack mirror, remove by the material of sputter reaction with the sample surfaces certain area, and then form different structures.This technology need not to use mask, is a kind of direct etching method without mask.And this method almost is applicable to all substances (for different material, etch rate can be different)

Concrete, as shown in Figure 4, comprise based on the method for focused-ion-beam lithography optical waveguide:

In etching process, in order to obtain high dutycycle (etching depth/etching width), must increase etching depth as far as possible and reduce the width of etching.In order to obtain in maximum the optical waveguide structure of superelevation dutycycle, special envoy of the present invention has used a kind of nanometer circle ring array structure to carry out etching, nanometer circle ring array structure as shown in Figure 5, the annulus in the each row and column is close to mutually, wherein r ₂And r ₁The external radius and the inside radius that represent respectively circular ring structure in the focused-ion-beam lithography process, the etching width of optical waveguide is g=2 * (r ₂-r ₁).Ion beam is for the easier focusing of circular ring structure, most ion beam energy can be well limited in circle ring area, circular ring structure is close to mutually so that focused ion beam in etching process, be positioned at the energy of circle ring area can be overlapping, thereby so that the penetration power of ion beam multiplication.In vertical direction at a high speed bombarding sample surfaces, so that etching depth can significantly increase, and then so that superelevation dutycycle structure becomes possibility.

In etching process, it is 20nm that the width of etching is fixed on minimum value, but because the error of device systems, might not be 20nm accurately after the etching.Increase as far as possible on this basis etching depth, and then obtain in maximum the waveguiding structure of superelevation dutycycle.Structure shown in Fig. 6, width are 20nm, and the degree of depth is about 15 μ m(1 μ m=1000nm=1 * 10 ^-6M) waveguiding structure, its corresponding dutycycle is 750.Top that it should be noted that waveguiding structure can present relatively serious damage, and this is caused by long etching.On the one hand be ion beam to the damage of body structure surface, be that the material that is etched deposits to the body structure surface that sustains damage again on the other hand.But below the about 2 μ m of sample surfaces, waveguiding structure has just become very vertical and homogeneous.For most of zone of waveguiding structure (part that 2 μ m are following), not only etching width minimum (20nm), and sidewall is vertical, homogeneous, and these all can reduce the loss of light in the waveguide process, so that the performance of waveguide increases substantially.

Make the optical waveguide that not only can obtain having in this way the superelevation dutycycle, and the sidewall of preparation-obtained waveguiding structure is almost completely vertical, just as shown in Figure 6.The loss that this almost vertical sidewall can reduce light greatly when transmitting therein, and because duct width is very little, most of energy of light wave can be limited in the waveguide region well.

This circle ring array structure can effectively be reduced in the again sedimentary effect in the focused-ion-beam lithography process, thereby significantly improves the side wall construction of device and increase etching depth.Another benefit of using this structure to carry out etching is high controllability.The structure of waveguide can control effectively by the inside and outside footpath of regulating annulus.This structure is finished and is saved in advance in the computer of focused-ion-beam lithography system, can directly call required corresponding construction when needing and carry out etching.Fig. 7 is for using the focused-ion-beam lithography legal effect comparison diagram of traditional wet method/plasma etching method and use circular ring structure.

Using another significant advantage of the method is to prepare the complicated rhombus optical waveguide that crosses one another, as shown in Figure 8.This structure can be widely used in preparing Fabry-Perot interferometer.The optical signalling of different mode is propagated in different light paths and is interacted, and phase place and energy size by accurate control light wave can effectively form the optics output with various different application backgrounds.Owing to phase differential interferes with each other, and further form interferometer between the light signal in the different optical channels.

The above only is preferred implementation of the present invention; should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the technology of the present invention principle; can also make some improvement and replacement, these improvement and replacement also should be considered as protection scope of the present invention.

Claims

1. method based on the focused-ion-beam lithography optical waveguide is characterized in that the method comprises:

S3, call described nanometer circle ring array structure from focused ion beam system, focused ion beam bombardment sample surfaces carries out etching, finishes preparation.

2. method as claimed in claim 1 is characterized in that the etching width minimum value of described optical waveguide is 20nm.