KR20180058619A - method for manufacturing optical switch and structure of the same - Google Patents

Abstract

The present invention discloses a method of manufacturing an optical switch. The method includes a step of forming a lower clad layer on a substrate, a step of forming first and second waveguides on the lower clad layer; a step of forming a thermoelectric element having first and second thermoelectric legs between the first and second waveguides; and a step of forming an upper clad layer on the first and second waveguides, the thermoelectric element, and a part of the lower clad layer. The step of forming the first and second waveguides may include a step of forming a silicon layer on the lower clad layer and a step of etching the silicon layer to form the first and second waveguides and preliminary thermoelectric legs of the first and second thermoelectric legs. The preliminary thermoelectric legs can be patterned simultaneously with the first and second waveguides.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of manufacturing an optical switch,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an optical switch and its structure, and more particularly, to a method of manufacturing an optical switch capable of efficiently modulating and / or switching light and a structure thereof.

Generally, an optical switch is a device that changes the optical path. For example, the optical switch may include a mechanical optical switch and a waveguide type optical switch.

The mechanical optical switch may be a switch for mechanically moving the optical element. The mechanical type optical switch has a small amount of internal light loss and leakage light attenuation, and can be easily produced because it is easy to manufacture. A mechanical optical switch can mainly include a switch of the type 1XN.

On the other hand, the waveguide type optical switch may include an NXN type switch. The waveguide type optical switch can be driven by the magneto-optical effect, the electro-optic effect, or the thermo-optic effect of the optical crystal. Thermo-optic effect can be a phenomenon in which the refractive index of a material changes with temperature. For example, the waveguide type optical switch may include waveguides of a Mach-Zehnder interferometer (MZI) scheme. Mach-Zehnder interferometer type waveguides can modulate and / or switch light to heat the heater electrode. The heater electrode may be disposed primarily on the waveguides. However, there is a disadvantage that the heater electrode can unevenly heat the waveguides and the cladding around the waveguide.

It is an object of the present invention to provide a method of fabricating an optical switch capable of patterning preliminary thermoelectric legs of a thermoelectric element simultaneously with first and second waveguides, and a structure thereof.

The present invention discloses a method of manufacturing a thermo-optical switch. A manufacturing method thereof includes the steps of: forming a lower clad layer on a substrate; Forming first and second waveguides on the lower clad layer; Forming a thermoelectric element having first and second thermoelectrons between the first and second waveguides; And forming an upper clad layer on a portion of the first and second waveguides, the thermoelectric element, and the lower clad layer. The forming of the first and second waveguides may include: forming a silicon layer on the lower clad layer; And etching the silicon layer to form the first and second waveguides and the preliminary thermoelectric legs of the first and second thermoelectrons.

According to an embodiment of the present invention, the step of forming the thermoelectric element includes the steps of: forming a first thermoelectric leg by injecting a first impurity into the first portions of the preheated thermoelectrons; Forming second thermoelectrons by injecting a second impurity different from the first impurity into the second portions of the preheated thermoelectrons; And forming first and second electrodes connecting the first and second thermoelectric legs in series.

According to an embodiment of the present invention, the first electrodes are formed between the first waveguide and the first and second thermoelectric legs, and the second electrodes are formed between the second waveguide and the first and second thermoelectric legs, As shown in FIG.

According to an embodiment of the present invention, the upper clad layer may be formed between the first and second waveguides and the first and second electrodes.

According to an embodiment of the present invention, the first and second waveguides may be formed in a first direction, and the thermoelectric legs may be formed in a second direction that intersects the first direction.

According to an embodiment of the present invention, the first and second waveguides include: optical coupling regions; And a phase shifting region between the light coupling regions. The thermoelectric element may be formed in the phase shifting region.

According to an embodiment of the present invention, the lower clad layer and the upper clad layer may include silicon oxide.

According to an embodiment of the present invention, the silicon layer may include crystalline silicon formed by a chemical vapor deposition method and a laser crystallization method.

According to one embodiment of the present invention, the silicon layer may comprise monocrystalline silicon, polysilicon, amorphous silicon, silicon nitride, or silicon oxynitride.

According to an embodiment of the present invention, when the silicon layer includes the single crystal silicon, the substrate, the lower clad layer, and the silicon layer may be silicon on insulator substrates.

An optical switch according to an embodiment of the present invention includes: a lower clad layer on a substrate; First and second waveguides on the lower clad layer; A thermoelectric element between the first and second waveguides; And a part of the lower clad layer, the thermoelectric element, and the upper clad layer on the first and second waveguides. Here, the thermoelectric elements may have the same height as the height of the first and second waveguides.

According to an embodiment of the present invention, the thermoelectric element comprises: a first thermoelectric leg; A second thermoelectrode parallel to the first thermoelectrode; A first electrode connected in series between the first and second thermoelectric legs and between the first and second thermoelectrons and the first waveguide; And a second electrode that connects the first and second thermoelectric legs in series and is disposed between the first and second thermoelectric legs and the second waveguide.

According to one example, the first and second waveguides comprise: optical coupling regions; And a phase shifting region between the light coupling regions. The thermoelectric element may be disposed within the phase shifting region.

As described above, the method of manufacturing the optical switch according to the concept of the present invention includes forming the first and second waveguides on the lower clad layer and forming the thermoelectric elements between the first and second waveguides . The forming of the first and second waveguides may include forming the silicon layer and etching the silicon layer to form the first and second waveguides and the thermoelectric elements between the first and second waveguides. And simultaneously patterning the preliminary thermoelectric legs.

1 is a plan view showing an example of an optical switch according to the concept of the present invention.
2 is a cross-sectional view taken along line I-I 'of FIG.
3 is a flow chart showing a method of manufacturing the optical switch of FIG.
Figs. 4 to 8 are process sectional views of Fig.
9 to 11 are process plan views of FIG.
12 is a flow chart showing an example of steps of forming the first and second waveguides of FIG.
13 is a flow chart showing an example of a step of forming the thermoelectric element of FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in different forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the concept of the invention to those skilled in the art, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. It is to be understood that the phrase "comprises" and / or "comprising" used in the specification exclude the presence or addition of one or more other elements, steps, operations and / or elements, I never do that. Also, in the specification, the terms solder, blocks, powders, spacers, and magnetic fields may be understood as meaning mainly used in the semiconductor field. The reference numerals shown in the order of description are not necessarily limited to those in the order of the preferred embodiments.

FIG. 1 shows an example of an optical switch 400 according to the concept of the present invention. 2 is a cross-sectional view taken along line I-I 'of FIG.

Referring to FIGS. 1 and 2, the optical switch 400 of the present invention may be an optical switch based on a thermo-optic effect of a Mach-Zehnder interferometer type. Alternatively, the optical switch 400 may be an optical waveguide switch. The optical switch 400 includes a substrate 10, a lower clad layer 20, a first waveguide 100, a second waveguide 200, a thermoelectric element 300, and an upper clad layer 30 . The substrate 10 may comprise glass and / or printed circuit boards. The lower clad layer 20 may be disposed on the substrate 10. The lower clad layer 20 may include a silicon oxide layer.

The first waveguide 100, the second waveguide 200, and the thermoelectric element 300 may be disposed on the lower clad layer 20. The first waveguide 100, the second waveguide 200, and the thermoelectric element 300 may include a silicon layer. For example, the first waveguide 100, the second waveguide 200, and the thermoelectric element 300 may include monocrystalline silicon, polysilicon, amorphous silicon, silicon nitride, or silicon oxynitride. The first waveguide 100 and the second waveguide 200 may transmit the light 18 in the first direction 1. The first and second waveguides 100 and 200 may have optical coupling regions 12 and a phase shifting region 14.

The optical coupling regions 12 may be regions for exchanging and / or switching the light 18 in the first and second waveguides 100 and 200. The distance between the first and second waveguides 100 and 200 in the optical coupling regions 12 is determined by the distance between the first and second waveguides 100 and 200 in the phase shifting region 14, . The width of each of the first and second waveguides 100 and 200 may increase in the phase shifting region 14 than in the optical coupling regions 12. [

The phase shifting region 14 may be disposed between the light coupling regions 12. The phase shifting region 14 may be a region for modulating the phase of the light 18. The first and second waveguides 100 and 200 in the optical coupling regions 12 may switch the light 18 having the modulated phase. One of the optical coupling regions 12 in front of the phase shifting region 14 is used as an input portion of the light 18 and the phase shifting region 14 is used as an input portion of the light 18, And the remaining one of the optical coupling regions 12 at the rear end may be used as an output portion of the light 18.

The thermoelectric element 300 may be disposed between the first and second waveguides 100 and 200 in the phase shifting region 14. [ The thermoelectric element 300 may have a height equal to the height of the first and second waveguides 100 and 200. According to one example, the thermoelectric element 300 may include thermoelectric legs 310 and electrodes 320. The thermoelectric legs 310 may extend in a second direction 2. The thermoelectric legs 310 may include first thermoelectric legs 312 and second thermoelectric legs 314. The first thermoelectric legs 312 may include a p-type semiconductor pattern. The second thermoelectric legs 314 may include an n-type semiconductor pattern. The electrodes 320 may connect the thermoelectric legs 310 in series. The electrodes 320 may include first electrodes 322 and second electrodes 324. The first electrodes 322 may be disposed between the first waveguide 100 and the thermoelectric legs 310. The second electrodes 324 may be disposed between the second waveguide 200 and the thermoelectric legs 310.

The upper clad layer 30 may be disposed on a portion of the lower clad layer 20, the first waveguide 100, the second waveguide 200, and the thermoelectric element 300. The upper clad layer 30 may include a silicon oxide layer.

The thermoelectric element 300 may heat and / or cool the first and second waveguides 100 and 200 in the phase shifting region 14 to form the first and second waveguides 100 and 200 Can be changed. The refractive index of the first and second waveguides 100 and 200 may increase in proportion to the temperature. The phase of the light 18 may vary according to the refractive index of the first and second waveguides 100 and 200 in the phase shifting region 14.

If the thermoelectric element 300 modulates the phase of the light 18 in the first waveguide 100 by about π (half wavelength) by heating and / or cooling the first waveguide 100, 18 may be provided to the second waveguide 200 in the optical coupling region 12 at the rear end of the phase shifting region 14. [ The light 18 can be output along the first waveguide 100 without switching to the second waveguide 200 if the phase of the light in the first waveguide 100 is unchanged or modulated by about 2? have. The thermoelectric element 300 may heat and / or cool the second waveguide 200 to switch the light 18 transmitted to the second waveguide 200 to the first waveguide 100. The present invention is not limited thereto and can be variously embodied.

A typical thermo-optic switch can switch light by selectively heating only one of the plurality of phase shifters using a heater. The optical switch 400 according to the present invention heats the first waveguide 100 in the phase shifting region 14 using the thermoelectric element 300 and cools the second waveguide 200, The switching efficiency of the switch 18 can be doubled as compared with a general thermo-optical switch.

A manufacturing method of the optical switch 400 constructed as described above will be described below.

3 is a flow chart showing a manufacturing method of the optical switch 400 of FIG. Figs. 4 to 8 are process sectional views of Fig. 2, and Figs. 9 to 11 are process plan views of Fig.

3, the method of manufacturing the optical switch 400 includes forming the lower clad layer 20 (S10), forming the first and second waveguides 100 and 200 (S20) , Forming the thermoelectric element 300 (S30), and forming the upper clad layer 30 (S40).

Referring to FIGS. 3 and 4, the lower clad layer 20 is formed on the substrate 10 (S10). The lower clad layer 20 may include a silicon oxide layer formed by a physical vapor deposition method, a chemical vapor deposition method, or a sol-gel method.

FIG. 12 shows an example of step S20 of forming the first and second waveguides 100 and 200 of FIG.

Referring to FIGS. 5, 6 and 12, the first and second waveguides 100 and 200 are formed on the lower clad layer 20 (S20). According to one example, forming the first and the waveguides 100 and 200 includes forming a silicon layer 302 (S22), forming the first and second waveguides 100 and 200 And patterning the spare thermoelectric legs 310a (S24).

Referring to FIGS. 5 and 12, the silicon layer 302 is formed on the lower clad layer 20 (S22). The silicon layer 302 may include crystalline silicon formed by a chemical vapor deposition method and a laser crystallization method. The substrate 10, the lower clad layer 20 and the silicon layer 302 may be silicon-on-insulator (SOI) substrates when the silicon layer 302 comprises crystalline silicon. Alternatively, the silicon layer 302 may comprise polysilicon, amorphous silicon, silicon nitride, or silicon oxynitride formed by a chemical vapor deposition process and / or a physical vapor deposition process.

Referring to FIGS. 6, 9 and 12, the silicon layer 302 is patterned to form the first and second waveguides 100 and 200 and the preliminary thermoelectric legs 310a (S24). The silicon layer 302 may be etched along a photomask pattern formed by a photolithographic method. The preliminary thermoelectric legs 310a may be formed between the first and second waveguides 100 and 200. The preliminary thermoelectric legs 310a may be formed in the phase shifting region 14 of the first and second waveguides 100 and 200. [

FIG. 13 shows an example of forming the thermoelectric element 300 of FIG. 3 (S30).

Referring to FIG. 13, the thermoelectric element 300 is formed using the preliminary thermoelectric legs 310a (S30). The step of forming the thermoelectric element 300 S30 may include forming the first thermoelectric legs 312 and forming the second thermoelectric legs 314 at step S34, And forming the first and second electrodes 322 and 324 (S36).

7, 10 and 13, a first impurity is ion-implanted into a part of the preliminary thermoelectric legs 310a to form the first thermoelectric legs 312 (S32). The first impurities may include a p-type conductive impurity (ex, boron (B), indium (In), or gallium (Ga) . ≪ / RTI >

Referring to FIGS. 11 and 13, a second impurity is ion-implanted into the remaining part of the preliminary thermoelectric legs 310a to form second thermoelectric legs 314 (S34). The second impurity may be different from the first impurity. For example, the second impurity may include (P) which is an n-type conductive impurity (ex), or arsenic (As).

Referring to FIGS. 1 and 13, first and second electrodes 322 and 324 for connecting the first and second thermoelectric legs 312 and 314 in series are formed (S36). The first and second electrodes 322 and 324 may be formed by a metal deposition process, a photolithography process, and a metal etching process.

2 and 3, an upper clad layer 30 is formed on a part of the lower clad layer 20, the first and second waveguides 100 and 200, and the thermoelectric element 300 (S40). The upper clad layer 30 may be formed between the thermoelectric element 300 and the first waveguide 100. The upper clad layer 30 may be formed between the thermoelectric element 300 and the second waveguide 200. The upper clad layer 30 may include a silicon oxide layer formed by a chemical vapor deposition method or a sol-gel method.

The above description is a concrete example for carrying out the present invention. The present invention includes not only the above-described embodiments, but also embodiments that can be simply modified or easily changed. In addition, the present invention includes techniques that can be easily modified by using the above-described embodiments.

Claims (13)

Forming a lower clad layer on the substrate;
Forming first and second waveguides on the lower clad layer;
Forming a thermoelectric element having first and second thermoelectrons between the first and second waveguides; And
And forming an upper clad layer on a part of the first and second waveguides, the thermoelectric element and the lower clad layer,
Wherein forming the first and second waveguides comprises:
Forming a silicon layer on the lower clad layer; And
And patterning the silicon layer to form the first and second waveguides and the preliminary thermoelectric legs of the first and second thermoelectric legs.
The method according to claim 1,
The step of forming the thermoelectric element comprises:
Injecting a first impurity into the first portions of the pre-heaters legs to form the first thermoresistant;
Forming second thermoelectrons by injecting a second impurity different from the first impurity into the second portions of the preheated thermoelectrons; And
And forming first and second electrodes connecting the first and second thermoelectric legs in series.
3. The method of claim 2,
Wherein the first electrodes are formed between the first waveguide and the first and second thermoelectric legs,
Wherein the second electrodes are formed between the second waveguide and the first and second thermoelectric legs.
3. The method of claim 2,
Wherein the upper clad layer is formed between the first and second waveguides and the first and second electrodes.
The method according to claim 1,
The first and second waveguides are formed in a first direction,
Wherein the thermoelectrons are formed in a second direction intersecting with the first direction.
The method according to claim 1,
The first and second waveguides comprise:
Optical coupling regions; And
A phase shifting region between the light coupling regions,
Wherein the thermoelectric element is formed in the phase shifting region.
The method according to claim 1,
Wherein the lower clad layer and the upper clad layer comprise silicon oxide.
The method according to claim 1,
Wherein the silicon layer comprises crystalline silicon formed by a chemical vapor deposition method and a laser crystallization method.
The method according to claim 1,
Wherein the silicon layer comprises monocrystalline silicon, polysilicon, amorphous silicon, silicon nitride, or silicon oxynitride.
10. The method of claim 9,
Wherein when the silicon layer comprises the single crystal silicon, the substrate, the lower clad layer, and the silicon layer are silicon on insulator substrates.
A lower clad layer on the substrate;
First and second waveguides on the lower clad layer;
A thermoelectric element between the first and second waveguides; And
A part of the lower clad layer, the thermoelectric element, and an upper clad layer on the first and second waveguides,
Wherein the thermoelectric element has a height equal to a height of the first and second waveguides.
12. The method of claim 11,
The thermoelectric element comprises:
A first thermoelectric leg;
A second thermoelectrode parallel to the first thermoelectrode;
A first electrode connected in series between the first and second thermoelectric legs and between the first and second thermoelectrons and the first waveguide; And
And a second electrode that connects the first and second thermoelectrons in series and is disposed between the first and second thermoelectrons and the second waveguide.
12. The method of claim 11,
The first and second waveguides comprise:
Optical coupling regions; And
A phase shifting region between the light coupling regions,
Wherein the thermoelectric element is disposed within the phase shifting region.

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