KR100394018B1 - method for production of optical communication type optical super prism - Google Patents

Abstract

The present invention is to fabricate an optical communication device that integrates a wave guide and photonic crystals to compensate for the disadvantages of each technology alone, and sequentially forms a lower clad layer, a core layer, and a hard mask layer on a Si substrate. Depositing and patterning a hard mask with a pre-designed core circuit according to a photo-lithography method to form a slab wave guide, forming a plurality of holes in a defined shape on the hard mask, and using the PR in which the holes are formed. To form holes by etching the hard mask and the core layer to expose the lower clad layer at the same position as the holes, and then depositing either poly or amorphous silicon between the holes formed in the hard mask and the core layer. Forming a crystal and depositing an upper clad layer on the front surface thereof. Since standing air, it is possible to configure a small size of the device can be manufactured to a preferred wavelength demultiplexer for high integration.

Description

Method for production of optical communication type optical super prism

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to devices for optical communications, and more particularly to fabrication of devices in which photonic crystals and wave guides are integrated by a batch process for optical communication applications.

The wave guide is a device that performs a function of splitting multiple signal lights multiplexed in a wavelength multiple optical communication method or combining multiple signal lights into one waveguide. An array wave guide using an array waveguide grating. : AWG) is mainly used.

However, the AWG device has the following problems.

First, the AWG device needs to make waveguides individually for each path through which light travels, and there is a problem in that the size of the device becomes large because the radius of bending of each waveguide is limited.

Secondly, the AWG device cannot avoid penetration of the optical signal to some extent even if the refractive index difference between the core constituting the waveguide and the clad is large, and in view of the limitation of size, the first problem, the waveguide pitch Since it is impossible to increase the pitch sufficiently, it is difficult to reduce cross talk.

Next, a description will be given of a conventional invention for making a wavelength branching circuit using a photonic crystal.

Photonic crystals are materials that have a periodic arrangement of dielectrics. In general, materials with a crystalline structure have a periodic potential due to the regular arrangement of the atoms or molecules that make up the material, and thus are affected by the propagation of electrons. Affect

An important phenomenon that arises is the formation of a band gap.

This concept applies equally to photons, where the dielectric acts as a hierarchy for the photons.

In this case, as in the case of the former, a band gap is formed, which is distinguished from the band gap of the electron, and is called a photonic band gap.

This is why photonic crystals are called photonic band gap meterial (PBG).

These photon crystals became known in 1987 when Yablonobitch and John each independently announced that the same band gap concept could be applied to light.

Since it is a dielectric that acts as a potential for light, it is suggested that periodic arrangements can result in photonic band gaps that can selectively pass electromagnetic waves with specific wavelengths or prevent them from progressing.

This proposal was realized in 1989 by Yablonovitch's group experimentally showing the existence of photon band gaps in two-dimensional photonic crystals.

Since 1991, the Yablonovitch Group has produced a three-dimensional photonic crystal with a band gap in the frequency domain corresponding to the microwave region, and has shown the possibility that the photonic crystal can be applied as a real device. have.

In addition, Hideo Kosaka of NEC in Japan and Shojiro Kawakami of Tohoku University use photonic light wave to connect wavelength spectrum circuit, laser, light receiving element, and optical fiber by using highly dispersive property of photonic crystal. circuit).

However, the above-described invention related to the photonic crystal application has the following serious problems.

The first is the problem of enduring losses.

That is, when an optical signal enters the photonic crystal from the outside, the laser propagates through free space or reaches the photonic crystal directly through the fiber.

In all these cases, there is a loss due to the difference in refractive index in and outside the photonic crystal, and the thickness of the photonic crystal becomes thinner to a few microns or less in consideration of the mode of the optical signal and the difficulty of the etching process. loss due to incorrect alignment.

Second is the problem of the output path of the split light.

That is, the light branched inside the photonic crystal comes out again and has the same loss problem as the first problem, while the propagation direction of the light splitted according to the nature of the photonic crystal is applied to the optical signal of each wavelength. All of them are different, and considering all of them, designing a focusing lens will be a great difficulty in device design.

Accordingly, an object of the present invention is to provide a wavelength branching circuit which is suitable for miniaturization of device size, improvement of device characteristics such as high speed and transmission efficiency, and high integration. .

Another object of the present invention is to propose an optical communication device fabrication technique that integrates wave guides and photonic crystals and compensates for the disadvantages of each technique alone.

1A to 1E are views showing a process for forming a slab wave guide in a super optical prism for optical communication according to the present invention;

2A-2B are top plan views of the hard mask patterned in FIG. 1E.

3A to 3I illustrate a process for forming photonic crystals in a super optical prism for optical communication according to the present invention.

4 shows a two-dimensional photon crystal made in accordance with the present invention.

* Explanation of symbols for main parts of the drawings

1 substrate 2 cladding layer

3: core layer 4: hard mask layer

5: PR 6: Align key

7: poly or amorphous silicon

8: upper cladding layer

In order to achieve the above object, a method of manufacturing a super optical prism for optical communication according to the present invention includes the steps of sequentially depositing a lower clad layer, a core layer, and a hard mask layer on a Si substrate, and PR on the hard mask layer. Applying and patterning, patterning the hard mask with a predesigned core circuit according to the photo-lithography method to form a slab wave guide, coating the PR over the hard mask, and then applying a plurality of shapes in a defined form through a mask operation. Forming a hole, etching the hard mask and the core layer to expose the lower clad layer at the same position as the hole by using the hole in which the hole is formed, and forming the hole, removing the PR, and removing the hard mask and the core Form photonic crystals by depositing either poly or amorphous silicon between the holes formed in the layer And depositing an upper clad layer on the entire surface.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

Referring to the accompanying drawings, a preferred embodiment of a method for manufacturing a super optical prism for optical communication according to the present invention will be described.

1A to 1E are diagrams showing a process for forming a slab wave guide in a super optical prism for optical communication according to the present invention.

First, as shown in FIG. 1A, the lower clad layer 2 is deposited on the Si substrate 1, and then the core layer 3 is deposited on the lower clad layer 2.

In this case, SiO ₂ glass is used as the lower clad layer 2, and SiO ₂ -GeO ₂ glass is used as the core layer 3.

Subsequently, a hard mask layer 4 for lithography is deposited on the core layer 3 as shown in FIG. 1B.

In this case, poly Si is used for the hard mask layer 4, and in some cases, a metal such as Cr, Al, or a multilayer film thereof is used.

The hard mask layer 4 has a silicic acid dioxide and a high etch selectivity.

Subsequently, a PR 5 is coated on the hard mask layer 4 as shown in FIG. 1C.

The PR 5 is patterned as shown in FIG. 1D, and the hard mask 4 is patterned by a photo-lithography method using a core circuit designed as shown in FIG. 1E.

Here, the etching method typically uses reactive ion etching (RIE), but wet etching is also possible.

2A-2B are top plan views of the hard mask patterned in FIG. 1E.

2A to 2B may have a different patterning form according to the design of the circuit, and the hard mask pattern 4 may include a form of an alignment key 6 of a photo operation for process integration in addition to a wave guide form. do.

The alignment key 6 may have various shapes as long as it meets the cross shape or the purpose as shown in FIG. 2B.

The alignment key 6 is positioned at the edge of the wafer or at the periphery of the circuit, which does not serve as a wave guide, and may be changed in shape and position according to a subsequent process method.

That is, it facilitates subsequent mask work for forming photonic crystals and has freedom as long as the operation of the designed circuit is not disturbed.

The reason for the need for the alignment key 6 is that the conventional wave guide mask uses a contact mask that is processed all over the wafer at a time, thereby reducing the small feature size required for the photonic crystal patterning. This is because of the difficulty in implementation.

Therefore, the masking operation for photonic crystals requires an alignment step because a mask such as 5X or 4X, which is a stepper type used in a general CMOS process, is used.

And the size of the align key (6) is usually about 100um in length of one side.

3A to 3I illustrate a process for forming photonic crystals in a super optical prism for optical communication according to the present invention.

3A and 3B, after the PR is coated on the hard mask 4 patterned according to the core circuit designed as in FIG. 1E, the hard mask 4 is exposed to a plurality of holes in a defined form through a mask operation. To form.

In this case, an oxynitride (SiON) or an organic B-arc (Bottom anti-reflection-coating) may be used as an anti-reflection layer.

Subsequently, as illustrated in FIG. 3C, the hard mask 4 is etched using RIE or wet etching using PR having holes formed through the mask operation.

3D, the PR layer is etched to the core layer 3 using the hard mask as a barrier after the PR strip so that the lower clad layer 2 is exposed.

3E is a plan view illustrating a structure in which holes for forming photonic crystals are formed through the process of FIG. 3D.

Next, as shown in FIG. 3F, poly or amorphous silicon 7 is filled between the etched holes to form photonic crystals using the refractive index difference between the silicon and the oxide.

At this time, the pitch of the photonic crystals useful for the optical wavelength range of 1.3 to 1.55 um used in the conventional optical communication is a sub-micron region of about 1 um or less, and the hole ) Is also equal to the photonic crystal pitch.

At this time, when the size of the hole is reduced, it is difficult to fill it in a normal case, so that a void may occur in the middle.

Therefore, in the present invention, in the case of CVD poly or amorphous silicon (amorphous silicon) process, even if the size of the hole is small enough such as 1000 특성 due to the material and process characteristics, it is possible to solve the problem of voids because the hole can be well filled without voids. Can be.

Then, as shown in FIG. 3g, the silicon 7 of the upper front surface is removed by a wet or dry method for the subsequent process, and the silicon is present only in the hole.

Of course, in addition to poly or amorphous silicon, if the material has a difference in oxide and refractive index, various materials such as polymers or nitride may be used in the hole instead of poly in consideration of process compatibility and circuit design. have.

The structure at this time is shown in a plan view as shown in Fig. 3h.

In order to complete the wave guide, as shown in FIG. 3I, the upper clad layer 8 is deposited and patterned to fabricate a super optical prism for optical communication.

4 is a view showing a two-dimensional photon crystal prepared in accordance with the present invention.

As described above, according to the present invention, a photonic crystal having a slab wave guide on the surface of a substrate and a periodic structure of a medium having a different refractive index are formed on a two-dimensional grating.

The photonic crystal causes anisotropy of refractive index dispersion, and the anisotropy of the refractive index dispersion causes the light of different wavelengths to propagate in different paths. That is, it exhibits a behavior similar to that of a normal optical prism effect.

As described above, the method for manufacturing a super-optical prism for optical communication according to the present invention can be configured with a small size of the device, and can manufacture a wavelength branch circuit that is very suitable for high integration.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (9)

Sequentially depositing a lower clad layer, a core layer and a hard mask layer on the Si substrate, Applying and patterning PR on the hard mask layer to pattern the hard mask with a predesigned core circuit to form a slab wave guide; After coating the PR on the hard mask, forming a plurality of holes in a defined form through a mask operation; Forming a hole by etching the hard mask and the core layer so that the lower clad layer is exposed at the same position as the hole by using the hole in which the hole is formed; Removing the PR and depositing either poly or amorphous silicon between the holes formed in the hard mask and the core layer to form photonic crystals; A method of manufacturing a super optical prism for optical communication, comprising the step of depositing an upper clad layer on a front surface. The method of claim 1, The lower clad layer is a SiO ₂ glass is used, the core layer is a SiO ₂ -GeO ₂ glass is characterized in that a super optical prism manufacturing method for optical communication. The method of claim 1, The hard mask layer is a poly-Si, Cr, Al, any one of them, or a multi-layered film of these, characterized in that a super optical prism manufacturing method for optical communication. The method of claim 1, The etching method according to the hard mask patterning is a method of manufacturing a super-optic prism for optical communication, characterized in that using any one of reactive ion etching (RIE) or wet etching. The method of claim 1, And said hard mask pattern further comprises an align key. The method of claim 5, The alignment key is a super optical prism manufacturing method for optical communication, characterized in that formed in the edge of the wafer or the peripheral portion of the circuit does not act as a wave guide. The method of claim 5, The alignment key has a size of one side of about 100um in length, wherein the optical communication super optical prism manufacturing method. The method of claim 1, The mask operation for forming the plurality of holes is a method of manufacturing a super-optic prism for optical communication, characterized in that using an oxynitride (SiON) or organic B-arc as an anti-reflection layer (anti-reflection layer). The method of claim 1, A method of manufacturing a super optical prism for optical communication, comprising depositing any one of polymers and nitrides between the hard mask and the holes formed in the core layer.