KR20100032969A - Method of manufacturing a optical modulator array - Google Patents

Abstract

PURPOSE: A method for manufacturing an optical modulator array is provided to perform the under cut process of a sacrificial layer after the wet process of a process which forms a upper electrode pad. CONSTITUTION: An insulation layer is formed on a substrate(100). A sacrificial layer(300) is formed on the insulation layer. A structural layer(500) is formed on the sacrificial layer. Array is formed on the both end of the structural layer. A ribbon hole is formed by etching the structural layer except a region in which an upper reflective layer is formed. A upper electrode pad which connects to the upper electrode of an piezoelectric driving body(600) is formed. An upper light reflective layer(910) is formed on the center of the structural layer. A lower light reflective layer(930) is formed on the insulation layer through the ribbon hole. A support part is formed by under-cut etching the sacrificial layer.

Description

Method of manufacturing a optical modulator array

The present invention relates to a method for manufacturing an array of light modulation elements, and more particularly, to perform the undercut forming process of a sacrificial layer after a wet process such as an upper electrode pad forming process to remove foreign substances remaining on the substrate. A method of manufacturing a modulation element array.

MEMS (Micro Electro Mechanical System) refers to a micro electromechanical system or device, and MEMS technology is a technology for forming a three-dimensional structure on a silicon substrate using semiconductor manufacturing technology.

MEMS is applied to the optical field as one of various application fields. MEMS technology enables the fabrication of optical components smaller than 1mm, enabling ultra-compact optical systems.

Micro-optical components such as optical modulator elements and micro lenses, which are miniature optical systems, have been adopted and applied to communication devices, displays, and recording devices due to advantages such as fast response speed, small loss, and ease of integration and digitization.

The optical modulator device is divided into a direct method of directly controlling the on / off of light and an indirect method using reflection and diffraction of light, and the indirect method is divided into an electrostatic method and a piezoelectric method according to the method of being driven again.

The optical modulator device requires a light reflection layer for reflecting and diffracting light regardless of its driving method, and the light reflection characteristics of the light reflection layer must be maximized to improve the light diffraction efficiency of the light modulator device.

In addition, in order to maximize the light reflection characteristics of the light reflection layer, accurate implementation of the ribbon in which the light reflection layer is laminated is essential.

1 is a view showing a part of a process for manufacturing an optical modulator element according to the prior art.

As shown in FIG. 1A, in the prior art, the structure layer 5 forming the ribbon and the sacrificial layer 3 stacked below the structure layer 5 are patterned in a step before forming the light reflection layer 7. At this time, as shown, the sacrificial layer 3 is undercut to the lower portion of the structure layer 5, the occurrence of such undercut to secure a space for the structure layer 5 can be driven by a piezoelectric drive (not shown). It has been understood to be necessary to do so.

However, in the related art, in addition to the formation of the light reflection layer 7 after the sacrificial layer 3 is undercut, a wet process such as an Au pad (not shown) forming process formed on the upper electrode of the piezoelectric driving body is involved. There was a problem in that the foreign material 9 remained on the substrate 1 in the portion where the sacrificial layer 3 was undercut.

That is, as shown in FIG. 1B, the part where the sacrificial layer 3 is undercut is difficult to penetrate the cleaning solution according to the wet process, so that the foreign matter 9 due to the wet process such as the formation of the Au pad remains on the substrate. There was a problem remaining in the modulation device.

The present invention was created to solve the problems of the prior art as described above, and proposes a method of manufacturing an optical modulation device array capable of overcoming the problem of foreign matter remaining by undercut of a sacrificial layer.

According to an aspect of the present invention, there is provided a method of fabricating an optical modulation device array, the method comprising: (a) forming an insulating layer on a substrate, forming a sacrificial layer on the insulating layer, and forming a structure layer on the sacrificial layer; (b) forming a plurality of piezoelectric driving bodies arranged side by side on both side ends of the structure layer and having an upper electrode and a lower electrode; (c) forming a ribbon hole by etching a portion of the center portion of the structure layer except for a region in which an upper reflective layer is to be formed; (d) forming an upper electrode pad electrically connected to the upper electrode of the piezoelectric driver; (e) etching the sacrificial layer exposed by the ribbon hole; (f) forming an upper light reflection layer for reflecting or diffracting incident light in a central portion of the structure layer, and forming a lower light reflection layer for reflecting or diffracting incident light on the insulating layer through the ribbon hole; And (g) undercutting the sacrificial layer to form a support on an end side of the lower portion of the piezoelectric driver.

As a preferred feature of the present invention, the forming of the piezoelectric driver may include (i) sequentially forming a lower electrode layer, a piezoelectric layer, and an upper electrode layer to form the plurality of piezoelectric driver bodies on both ends of the structure layer. Laminating with; And (ii) etching the lower electrode layer, the piezoelectric layer and the upper electrode layer such that the plurality of piezoelectric drivers are arranged side by side on both side ends of the structure layer to form an array.

In another preferred embodiment of the present invention, after the forming of the piezoelectric drive body, the method may further include forming an upper insulating layer covering the piezoelectric drive body.

In another preferred aspect of the present invention, the upper insulating layer has an opening exposing the upper electrode and the lower electrode.

In another preferred embodiment of the present invention, the forming of the light reflection layer may include: (i) applying the mask layer on an open portion of the structure layer and on the piezoelectric driver; (Ii) forming a pattern in which a region of the center portion of the structure layer to form the upper reflective layer is opened in a pattern portion open to an upper portion of the mask layer; (Iv) depositing a light reflecting material on the upper part of the mask layer and an open pattern portion, and forming the lower light reflecting layer reflecting or diffracting incident light on the insulating layer through the hole; And (iii) removing the mask layer and the light reflection material stacked on the mask layer to complete the upper light reflection layer.

The features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings.

Prior to that, terms and words used in the present specification and claims should not be construed in a conventional and dictionary sense, and the inventor may properly define the concept of the term in order to best explain its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

According to the present invention, since the undercut process of the sacrificial layer is performed after a wet process such as an upper electrode pad forming process, foreign matters can be prevented from remaining in the undercut portion of the sacrificial layer above the substrate.

Hereinafter, a preferred embodiment of the optical modulator device manufacturing method according to the present invention will be described in detail with reference to the accompanying drawings. Throughout the accompanying drawings, the same or corresponding components are referred to by the same reference numerals, and redundant descriptions are omitted.

2 to 11 are diagrams showing a method of manufacturing an optical modulator device according to a preferred embodiment of the present invention in the order of process.

First, as shown in FIG. 2, the sacrificial layer 300 is formed on the substrate 100. Materials constituting the substrate 100 include silicon (Si), alumina (Al 2 O 3), zirconia (ZrO 2), quartz (Quartz), silica (SiO 2), and the bottom and top layers of the substrate 100. Can also be formed using other heterogeneous materials. Here, the sacrificial layer 300 may be etched so that the ribbon may be spaced apart from the substrate 100 by a predetermined interval through a later process. In this case, the material used as the sacrificial layer 300 may be silicon (Si) or polysilicon (Poly-Si).

In this case, an etchant that serves as an etch stop layer between the substrate 100 and the sacrificial layer 300, and etches the material used as the sacrificial layer 300, wherein the etchant is an etching gas or an etching process. Solution) may further include an insulating layer (not shown) made of silica (SiO 2) or the like having a high selectivity.

Next, as shown in FIG. 3, the structure layer 500 is formed on the sacrificial layer 300. The structure layer 500 may have a hole formed in the ribbon through a later process. Here, the material used as the structure layer 500 may be a material of silicon nitride series (SiXNY) such as Si 3 N 4.

Next, as shown in FIG. 4, the piezoelectric driver 600 is formed on both ends of the structure layer 500. To form this, first, the lower electrode 610, the piezoelectric layer 650, and the upper electrode 630 are sequentially stacked.

In this case, as an electrode material of the lower or upper electrode 630, platinum (Pt), nickel (Ni), gold (Au), aluminum (Al), titanium (Ti), IrO 2, RuO 2, and the like may be used. Any combination of electrode materials may be used.

In addition, a piezoelectric material such as PZT, PNN-PT, PLZT, AlN, or ZnO may be used as the piezoelectric layer 650, and an element such as lead (Pb), zirconium (Zr), zinc (Zn), or titanium (Ti) may be used. It is also possible to use a piezoelectric electrolytic material comprising one or more.

In another embodiment, a protective layer (not shown) may be formed on the structure layer 500, and a bonding layer (not shown) may be formed on the protective layer. In this case, the protective layer serves to protect the upper surface of the structure layer 500 disposed below the lower electrode 610 and the bonding layer to be etched later, and a low temperature oxide (LTO) material such as SiO 2. This can be used.

In addition, the bonding layer serves to bond the upper surface of the protective layer and the lower electrode 610, and any one of insulating materials such as Al 2 O 3, TiO 2, TiN, TiSiN, TaN, and Ta 2 O 3 having excellent adhesion may be used. have.

Thereafter, the lower electrode 610 layer, the piezoelectric layer 650, and the upper electrode 630 layer may be removed through an etching process to form the piezoelectric driver 600 on both sides of each ribbon.

Next, as shown in FIG. 5, an upper insulating layer 700 is applied to electrically shield and protect the upper electrode 630 and the lower electrode 610 from the external environment.

Next, as shown in FIG. 6, the upper insulating layer 700 except for the upper insulating layer 700 formed on the piezoelectric driver 600 is removed, and the upper insulating layer 700 is formed on the piezoelectric driver 600. The upper electrode opening 710 and the lower electrode opening 730 are patterned on the upper insulating layer 700. This is to apply a voltage to the piezoelectric driver 600 through the upper electrode opening 710 and the lower electrode opening 730. In this case, a mask layer (not shown) is applied to remove the upper insulating layer 700, and after removing the mask layer applied on the ribbon, the upper insulating layer 700 is etched and removed according to a pattern formed on the mask layer. can do.

Next, as shown in FIG. 7A, a ribbon hole is formed in the structure layer 500. The structure layer 500 includes a piezoelectric driving body with a portion of the sacrificial layer 300 formed at a lower portion thereof by a process described below. It is configured to drive up and down by 600, wherein the predetermined portion of the structure layer 500 that can move up and down through the drive space secured by the removal of the sacrificial layer 300 is the central portion of the structure layer 500 Hereinafter, the "center portion of the structure layer 500" will be abbreviated as "ribbon". However, when the position of the driving space secured as described above is changed, the position of the ribbon of the structure layer 500 may also vary accordingly.

After forming a pattern for forming a ribbon hole in a mask layer (not shown) to form a ribbon hole in the structure layer 500, the ribbon hole is etched in the structure layer 500 according to the pattern formed in the mask layer. Then, the mask layer is removed.

In the present embodiment, the ribbon hole is formed only in the structure layer 500 by adjusting the etching amount, and at this time, the sacrificial layer 300 positioned below the ribbon hole may be partially etched in the thickness direction. Make sure it is not an obstacle.

FIG. 7B is a plan view of a portion of the optical modulation device array shown in FIG. 7A, and the shape of the ribbon hole formed in the structure layer 500 is shown in more detail.

FIG. 7C is a cross-sectional view of the light modulation device array shown in FIG. 7A taken along a line A-A, and FIG. 7D is a cross-sectional view of the light modulation device array shown in FIG. 7A taken along a line B-B. As shown therein, the state of the light modulation element array according to the process of the step where only the structure layer 500 is etched is shown in more detail.

Lines A-A and B-B in the present specification are defined in the directions shown in FIGS. 7A and 7B, and overlapping views and descriptions are omitted in the following drawings.

Next, as shown in FIG. 8, an upper electrode pad 810 for electrically connecting the upper electrode 630 of the piezoelectric driver 600 is formed. The upper electrode pad 810 is connected to the upper electrode 630 through the upper electrode opening 710 formed in the upper insulating layer 700, and may be made of a conductive metal such as Au.

As shown in detail in FIG. 7C, the sacrificial layer of the optical modulation device array is not undercut under the structure layer 500 in the process of forming the upper electrode pad 810 according to the present step. Therefore, even when the upper electrode pad 810 is formed by the wet process, foreign matter does not remain on the substrate on the undercut portion of the sacrificial layer 300.

Next, as shown in FIG. 9A, the sacrificial layer 300 positioned below the ribbon hole is removed. In this case, the sacrificial layer 300 may be etched using the ribbon hole as a mask, and a separate mask (not shown) may be additionally used. Undercut may occur in a portion of the sacrificial layer 300 formed under the ribbon hole by the etching process of this step. However, the size of the hole formed in the sacrificial layer 300 does not greatly exceed the size of the ribbon hole.

FIG. 9B is a cross-sectional view of the light modulation device array shown in FIG. 9A taken along the line A-A, and FIG. 9C is a cross-sectional view of the light modulation device array shown in FIG. 9A taken along the line B-B. As shown in this figure, in this step, the sacrificial layer 300 is etched into a shape corresponding to the shape of the ribbon hole, in which an undercut may occur.

Next, as illustrated in FIG. 10A, a light reflection layer is formed at the center portion of the structure layer and the portion exposed to the ribbon hole of the substrate. First, a new mask layer (not shown) is applied on the ribbon, and a pattern is formed by removing portions of the mask layer on which the upper reflective layer and the lower reflective layer are to be formed. Thereafter, the light reflection material is stacked according to the pattern formed on the mask layer to form an upper reflection layer and a lower reflection layer, and the light reflection material stacked on the mask layer and the mask layer is removed. Here, as the light reflection material, for example, various metal materials (Al, Pt, Cr, Ag, etc.) may be used.

In this case, various methods may be used as a method of removing the mask layer. After removing the mask layer, the light reflecting material may be lifted off to remove the light reflecting material stacked on the mask layer. Done. Lift off refers to a method in which the material on top of the mask layer is also removed while the mask layer is removed.

Through this process, the light reflection material stacked on the mask layer and the mask layer can be removed.

As a result, the light reflecting material that is not removed through the above-described process, that is, the light reflecting material stacked on the reflective region of the ribbon forms the upper light reflecting layer 910, and the light reflecting material stacked on the substrate 100. The lower light reflection layer 930 is formed.

On the other hand, as shown, the upper light reflection layer 910 is formed to cover the lower electrode 610 of the piezoelectric driver 600, the lower electrode 610 and the upper light reflection layer 910 of the piezoelectric driver 600. It is also possible to make it a structure which makes it electrically connected.

FIG. 10B is a cross-sectional view of the light modulator array shown in FIG. 10A taken along line AA, and FIG. 10C is a cross-sectional view of the light modulator array shown in FIG. 10A taken along line BB. The arrangement of the upper light reflecting layer 910 and the lower light reflecting layer 930 formed is shown in more detail.

Next, as shown in FIG. 11, the sacrificial layer 300 under the ribbon is removed to complete the light modulator array. By removing the sacrificial layer 300 formed under the ribbon, a space in which the ribbon can be driven up and down is provided. At this time, the portion of the sacrificial layer 300 remaining below the end side of the piezoelectric drive body 600 and supporting the piezoelectric drive body 600 is referred to as a support part.

FIG. 11B is a cross-sectional view of the light modulation device array shown in FIG. 11A taken along line AA, and FIG. 11C is a cross-sectional view of the light modulation device array shown in FIG. 11A taken along line BB. The complete photomodulation device array is shown in detail with the sacrificial layer 300 removed.

According to the present exemplary embodiment, since the undercut process of the sacrificial layer 300 is performed after the upper electrode pad 810 is formed, the foreign material may be prevented from remaining in the undercut portion.

On the other hand, the present invention is not limited to the described embodiments, it is obvious to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, such modifications or variations will have to belong to the claims of the present invention.

1 is a view showing a part of a process for manufacturing an optical modulator element according to the prior art.

2 to 11 are diagrams showing a method of manufacturing a light modulator array according to a preferred embodiment of the present invention in the order of process.

<Description of Major Symbols in Drawing>

100 substrate 300 sacrificial layer

500 Layer 600 Piezoelectric Drive

700 Upper insulation layer 910 Upper light reflection layer

930 lower light reflection layer

Claims (5)

(a) forming an insulating layer on the substrate, forming a sacrificial layer on the insulating layer, and forming a structure layer on the sacrificial layer; (b) forming a plurality of piezoelectric driving bodies arranged side by side on both side ends of the structure layer and having an upper electrode and a lower electrode; (c) forming a ribbon hole by etching a portion of the center portion of the structure layer except for a region in which an upper reflective layer is to be formed; (d) forming an upper electrode pad electrically connected to the upper electrode of the piezoelectric driver; (e) etching the sacrificial layer exposed by the ribbon hole; (f) forming an upper light reflection layer for reflecting or diffracting incident light in a central portion of the structure layer, and forming a lower light reflection layer for reflecting or diffracting incident light on the insulating layer through the ribbon hole; And (g) undercutting the sacrificial layer to form a support on an end side of the lower portion of the piezoelectric drive body; Method of manufacturing an optical modulator array comprising a. The method of claim 1, Forming the piezoelectric drive body, (Iii) sequentially stacking a lower electrode layer, a piezoelectric layer, and an upper electrode layer to form the plurality of piezoelectric drive bodies on both ends of the structure layer; And (Ii) etching the lower electrode layer, piezoelectric layer and upper electrode layer such that the plurality of piezoelectric drivers are arranged side by side on both side ends of the structure layer to form an array. Way. The method of claim 1, After the step of forming the piezoelectric drive body, And forming an upper insulating layer covering the piezoelectric driving body. The method of claim 3, And the upper insulating layer has an opening exposing the upper electrode and the lower electrode. The method of claim 1, Forming the light reflection layer, (Iii) applying the mask layer over the open portion of the structure layer and the piezoelectric drive body; (Ii) forming a pattern in which a region of the center portion of the structure layer to form the upper reflective layer is opened in an upper portion of the mask layer and an open pattern portion; (Iv) depositing a light reflecting material on the upper part of the mask layer and an open pattern portion, and forming the lower light reflecting layer reflecting or diffracting incident light on the insulating layer through the hole; And (Iii) removing the mask layer and the light reflection material stacked on the mask layer to complete the upper light reflection layer; Method of manufacturing an optical modulation device array comprising a.

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