KR100459396B1 - Optical modulator and manufacturing method thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical modulator and a method of manufacturing the same, and a conventional optical modulator exhibits a mechanically weak structure due to stress concentration at a post portion connected to a bridge-type ribbon. Thus, the substrate is separated from the ribbon due to repetitive operation. There was a problem that the reliability of the operation is lowered such as a change in distance. In view of the above problems, the present invention includes a first insulating layer on the bottom surface of the upper substrate; A plurality of first ribbons and a plurality of second ribbons exposed through openings formed in the upper substrate and the first insulating layer, a part of which is bonded to a bottom surface of the first insulating layer and selectively driven; A plurality of ribbon pads disposed on a bottom surface of the first insulating layer and configured to apply a voltage to the plurality of first ribbons; A power supply line bent at both sides of the opening of the upper substrate and the first insulating layer to apply voltage to the plurality of second ribbons; A second insulating layer insulating the power line and the plurality of first ribbons; A lower electrode pad bonded to the power line through solder; A lower electrode connected to the lower electrode pad and positioned at a predetermined distance apart from the exposed portions of the first and second ribbons; A spacer spaced apart from the lower electrode by a predetermined distance and having a step higher than that of the lower electrode; A plurality of pads connected to the ribbon pads through solder; Comprising the third insulating layer and the lower substrate for supporting each of the structures to form a straight shape of the ribbon to distribute the stress has the effect of stabilizing the mechanical properties.

Description

Optical modulator and its manufacturing method {OPTICAL MODULATOR AND MANUFACTURING METHOD THEREOF}

The present invention relates to an optical modulator and a method of manufacturing the same, and in particular, to form a lower electrode and a ribbon on different substrates to disperse concentration of stress when driving the ribbon, thereby improving the stability and reliability of the mechanical driving of the optical modulator. An optical modulator and a method of manufacturing the same.

One-dimensional optical modulators used in conventional displays are diffracted by modulating the incident light, a representative example of which is GLV (GRATING LIGHT VALVE) of SLM (SILICON LIGHT MACHINE) of the United States. This GLV is a reflection type and has excellent speed and contrast characteristics, and is emerging as a modulator for the next display.

Hereinafter, with reference to the accompanying drawings will be described in detail the structure and operation characteristics of the GLV.

1 is a perspective view of the GLV, in which an insulating layer 2 is positioned on an upper portion of the substrate 1, and a lower electrode which is a high-temperature metal film such as tungsten on an upper portion of the insulating layer 2 is shown in FIG. (3) is located, and a plurality of bridges (4) in the form of a bridge, which is spaced apart from the lower electrode (3) by a predetermined distance and bonded to both sides of the insulating layer (2).

In addition, the plurality of ribbons 4 have a high light reflectivity and use a conductive material that can serve as an upper electrode for the lower electrode 3, and examples thereof include aluminum.

When a voltage is applied to the ribbon 4 at an alternate position among the lower electrode 3 and the plurality of ribbons 4, the ribbon 4 to which the voltage is applied is bent toward the substrate 1 side, and the surrounding voltage This unapplied ribbon 4 is fixed, so that the separation distance of the ribbon 4 from the substrate 1 can be changed.

As such, the upper surface of a part of the ribbon 4 is not coplanar with the upper surface of the other ribbon 4, thereby forming a grating for light incident from the outside, and using diffraction by the grating. It is possible to modulate the light.

That is, if no voltage is applied to the ribbon 4 to which voltage can be applied, the upper surfaces of all the ribbons 4 are all coplanar, which is the same effect as the mirror surface. To reflect light incident perpendicularly to the upper surface of the ribbon 4 as it is.

In addition, when a voltage is applied to the ribbon 4 configured to apply a voltage among the plurality of ribbons 4, the ribbon 4 to which the voltage is applied is bent toward the substrate 1 as described above. The upper surface of (4) shows a lattice structure, which diffracts the light irradiated vertically.

FIG. 2 is a right side view of FIG. 1 in which the ribbon 4 to which the voltage is applied is applied to the substrate 1 in an air gap region near the lower electrode 3 between the ribbon 4 and the substrate 1. It can be seen that the mechanical drive to reduce the separation distance.

FIG. 3A is a schematic diagram of reflecting the incident light as it is when no voltage is applied to all the ribbons 4, and FIG. 3B is a voltage applied to some of the ribbons 4 to form a lattice-like surface. As a schematic diagram of a process for diffraction, light can be modulated by using a change in the reflecting surface according to whether or not a voltage is applied as shown in the drawing.

In the operation of the GLV, the distance from which the ribbon 4 to which the voltage is applied is lowered to the substrate 1 side must be 1/4 of the wavelength of the irradiated light to obtain an optimal diffraction efficiency.

4 is a plan view and a side view of the projection apparatus using the GLV, and as shown therein, a prism that reflects light of the light source 41 toward the GLV 42 side and blocks light that is not diffracted in the GLV 42 ( 43); And a lens 44 for focusing the light diffracted by the GLV 42 and displaying it on the screen 45.

The projection apparatus using the GLV 42 separates the light diffracted from the GLV 42 and the light of the light source 41 which is directly reflected, and displays only the diffracted light. Accurate separation of light improves contrast.

When no voltage is applied to the ribbon 4 of the GLV 42 and the surface of the GLV 42 is flat like a mirror surface, the light of the light source 41 to be irradiated is vertically reflected, which is referred to as zero-order light. When the voltage is applied to a part of the ribbon 4 to generate a step on the reflective surface of the GLV 42 and the diffracted light is ± 1st order light, the prism is located at a portion where the 0th order light and ± 1st order light do not overlap. Position 43 so that only ± 1st order light can reach the lens 44, and the light focused through the lens 44 is displayed on the screen 45. As shown in FIG.

However, in the conventional optical modulator such as a shopping mall, the bridge ribbon 4 is mechanically driven up and down, so that stress STRESS is concentrated on the bridge post which is in contact with the insulating film 2, and thus the mechanical configuration is weak. There is a structural problem.

As described above, the conventional optical modulator modulates light by using a bridge-type ribbon mechanically up and down by an electric field, but stress is concentrated on a post portion, which is a part in contact with the substrate of the bridge-type ribbon, so that it is mechanically weak. As a result, there is a problem that the reliability of the operation is deteriorated, such as a change in the separation distance between the substrate and the ribbon due to the repeated operation.

In view of the above problems, the present invention fabricates a bridge-type ribbon and a lower electrode on different substrates, and then bonds the two substrates to disperse the stresses according to the mechanical driving of the ribbon, thereby mechanically stabilizing the plurality of protrusions. An optical modulator capable of forming a ribbon having a thin width by forming a structure having a structure that is cross-inserted into and intersecting with the protrusions of the ribbons facing each other, thereby securing a larger number of ribbons in the same area and improving light modulation efficiency; The purpose is to provide a method of manufacturing the same.

1 is a perspective view of a conventional optical modulator.

2 is a right side view of FIG. 1;

3A and 3B are schematic diagrams of reflected light depending on whether voltage is applied.

4 is a block diagram of a display device using FIG. 1;

5 is a top plan view of the optical modulator of the present invention.

FIG. 6 is a sectional view taken along the line A-A 'in FIG. 5; FIG.

Figure 7 is a bottom plan view of the optical modulator of the present invention.

FIG. 8 is a sectional view taken along the line A-A 'in FIG.

9 is a cross-sectional view of the optical modulator of the present invention.

** Description of symbols for the main parts of the drawing **

51, 71: substrate 52, 74: insulating layer

53: power supply line 54: insulating film

55: ribbon 56: signal electrode

72: Spacer 73: groove

75: lower electrode 76, 77: pad

78: solder

The above object is a first insulating layer located on the bottom surface of the upper substrate; A plurality of first ribbons and a plurality of second ribbons exposed through openings formed in the upper substrate and the first insulating layer, a part of which is bonded to a bottom surface of the first insulating layer and selectively driven; A plurality of ribbon pads disposed on a bottom surface of the first insulating layer and configured to apply a voltage to the plurality of first ribbons; A power supply line bent at both sides of the opening of the upper substrate and the first insulating layer to apply voltage to the plurality of second ribbons; A second insulating layer insulating the power line and the plurality of first ribbons; A lower electrode pad bonded to the power line through solder; A lower electrode connected to the lower electrode pad and positioned at a predetermined distance apart from the exposed portions of the first and second ribbons; A spacer spaced apart from the lower electrode by a predetermined distance and having a step higher than that of the lower electrode; A plurality of pads connected to the ribbon pads through solder; It is achieved by configuring the third insulating layer and the lower substrate for supporting the respective structures, and will be described in detail with reference to the accompanying drawings, the present invention as follows.

FIG. 5 is a plan view of the upper plate of the optical modulator of the present invention, and FIG. 6 is a sectional view taken along the line A-A 'in FIG. 5, and as shown therein, a substrate 51 having a centrally perforated portion, and An insulating layer (52) positioned at the upper front and at the perforated portion of the substrate (51) and used simultaneously as a ribbon having its central portion perforated; A power line 53 formed to have a bent portion on the insulating layer 52 and to which a voltage is applied; An insulating film 54 located above the power line 53; It is located on the upper side of the insulating film 54 and the insulating layer 52, alternately connected to the power line 53 through a contact hole located in the insulating film 54 and a plurality of concave-convex ends Ribbons 52 and 55 having portions and used as a plurality of reflective surfaces facing the uneven portions to engage with each other; It is composed of a signal electrode 56, which is separated from the ribbons 52 and 55, to which a signal is applied.

7 is a plan view of the lower plate of the optical modulator of the present invention, and FIG. 8 is a sectional view taken along the line A-A 'in FIG. 7, and is positioned at a predetermined distance from the center of the substrate 71 as shown in FIG. A spacer 72; Grooves (73) which are regions of low level of the substrate (71) spaced a predetermined distance from the outside of the spacer (72); An insulating layer 74 positioned on an upper front surface of the substrate 71 on which the spacer 72 and the groove 73 are located; A lower electrode 75 positioned on the insulating layer 74 in the region between the spacers 72; A pad 76 partially positioned at one groove 73 to supply power to the lower electrode 75; A pad 77 partially positioned at the groove 73 and independently positioned to face the ribbon 55 not connected to the power line 53 at the top plate; It is composed of a solder (78) located in the groove (73).

9 is a cross-sectional view of the optical modulator of the present invention, in which the upper plate and the lower plate are bonded to each other so that the substrate 71 is positioned below and the substrate 51 is positioned above.

That is, the substrate 71; A spacer 72 positioned above the center of the substrate 71 and protruding from the substrate 71; A groove 73 spaced apart from the spacer 72 by a predetermined distance and having a step lower than a surface of the substrate 72; An insulating layer 74 positioned on an upper surface of the substrate 71; A lower electrode 75 positioned on the insulating layer 74 in the region between the spacers 72; A pad 76 partially positioned at one groove 73 to supply power to the lower electrode 75; A plurality of pads 77, some of which are located in the grooves 73; A solder (78) located in the groove (73); Some of the plurality of ribbons 55 and the signal electrode 56 of the plurality of ribbons supported and electrically connected by the solder 78 at the upper side of the solder 78; A plurality of ribbons 55 whose ends are spaced apart from the lower electrode 75 by a predetermined distance and have a plurality of concave-convex end portions facing each other such that the concave-convex portions are engaged with each other; A power line 53 connected to a part of the plurality of ribbons 55 through an insulating layer 54 having a contact hole; An insulating layer 52 positioned on a flat front surface of the structure and having an opening at an upper side only of an end portion having a plurality of uneven structures of the ribbon 55; It is composed of a substrate 51 which is located on the upper front surface of the insulating layer 52 and has an opening that is wider from the opening of the insulating layer 52 toward the upper side.

Hereinafter, the optical modulator of the present invention as described above and a manufacturing method thereof will be described in more detail.

First, the silicon substrate 51 is prepared to form the top plate.

Next, an insulating layer 52 is deposited on the upper surface of the silicon substrate 51. At this time, the insulating layer 52 is deposited by using a low pressure chemical vapor deposition (LPCVD) method of silicon nitride (SixNy) excellent in insulation and excellent mechanical elasticity.

Then, a stable tungsten or tungsten silicide is deposited on the upper surface of the structure, even at high temperatures, connected to the pad and the pad through a photolithography process, and bent to have parallel portions at the center of the insulating layer 52. Power line 53 is formed.

At this time, the power line 53 is applied with the same voltage as the lower electrode of the optical modulator, so that the ribbon connected to the power line 53 is not mechanically driven.

Next, an insulating layer 54 is deposited on the upper surface of the structure. In this case, the insulating layer 54 is patterned so as to be positioned only on the top and side surfaces of the power line 53 and to form a contact hole so that a part of the power line 53 may be exposed in a plurality of areas.

Next, a plurality of ribbons 55 connected to the power line 53 through the contact hole by depositing aluminum, which is a metal to be used as a reflective film, on the upper surface of the structure, and the power line 53 A plurality of ribbons which are not connected to) are alternately formed.

At this time, the ribbon connected to the power line 53 does not need to form a pad portion, and the ribbon 55 not connected to the power line 53 is formed to have a pad.

In addition, the ribbons 55 are formed to cross each other at the central portion of the insulating layer 52. That is, the part located in the center part of the insulating layer 52 of the ribbon 55 is patterned so that it may have some unevenness | corrugation, and the uneven | corrugated part with the ribbon 55 which opposes does not contact each other, but is mutually crossed and fitted. Form in a stitchable pattern.

The ribbon 55, which is the aluminum pattern, etches a portion of the lower insulating layer 52 in the shape of the aluminum pattern to form the ribbon 55 in a laminated structure of the insulating layer and the ribbon 55.

Such a structure has the same effect as forming a plurality of ribbons that are applied with the same voltage, and each of the eight basic ribbons 55 as shown in the drawing is different from the conventional six ribbons formed in one unit. The shape can be modified to have three protrusions (two unevennesses), thereby producing the same effect as forming a total of 24 ribbons.

The ribbon 55 of the structure is formed, and the signal electrode 56 is formed at a position separate from the ribbon 55.

At this time, the signal electrode 56 connects the voltage applied from the lower plate to the ribbon 55 not connected to the power line 53 so that the ribbon can be driven.

Then, the bottom portion of the substrate 51 is etched to expose the uneven portion, which is the end of the ribbon 55, to manufacture a top plate.

In addition, a silicon substrate 71 is prepared to manufacture a lower plate.

Next, the upper portion of the substrate 71 is etched to a predetermined depth.

At this time, the region remaining without being etched is a symmetrical structure with respect to the center line of the substrate 71 and becomes a spacer 72 that determines a separation distance from the upper plate which is long in one direction. In other words, the spacer 72 is to prevent the ribbon and the lower electrode from being bonded and unusable while the ribbon 55 is driven from the upper plate.

The separation distance of the spacer 72 is made equal to the length of the shorter side of the central opening of the substrate 51 of the upper plate.

Next, the substrate 71 at a position spaced a predetermined distance apart from the spacer 72 is etched to form a groove 73 having a groove structure parallel to the spacer 72.

Next, an insulating layer 74 is deposited on the upper surface of the structure.

Then, a metal is deposited on the upper surface of the insulating layer 74, and the metal is patterned to form a lower electrode 75 positioned between the spacers 72 and on the lower electrode 75. In addition to supplying power, a pad 76 is formed to contact the power line 53 of the upper plate, and a pad 77 is spaced apart from the pad 76 by a predetermined distance and a part of the pad 77 is located in the groove 73. do.

Then, a lower melting point solder 78, such as AuSn, is placed in the groove 73 by electron beam deposition to manufacture a lower plate.

Then, the lower plate and the upper plate are bonded. At this time, the bonding method is inverted and the upper plate is arranged to be electrically connected to the pad 77 of the lower plate, the ribbon 55 of the upper plate and the signal electrode 56 through the solder 78, the other solder (78) The upper power line 53 and the lower pad 76 are connected to each other by using the solder 78 through the solder 78.

The role of the solder 78 is to determine the separation distance between the upper plate and the lower plate and to electrically connect the respective portions of the upper plate and the lower plate, the ribbon 55 by the voltage applied to the pad 76 on the lower plate side It has a structure that allows it to be driven mechanically.

In the above configuration, the ribbon 55 is not a bridge type as in the prior art, and is positioned in parallel with the substrates 51 and 71, and the stress generated by the driving of the ribbon 55 is applied to the substrate 51. It can be easily dispersed through the to improve the mechanical stability by the drive of the ribbon (55).

The characteristics of the present invention as described above is to form a drive portion of the basic ribbon 55 in a plurality of uneven structure, that is, a structure having a plurality of protrusions in the drive portion, thereby improving the light modulation efficiency in the same area, the ribbon ( 55) is formed in a rod-like structure parallel to the substrate rather than a bridge having a portion in contact with the substrate, a portion spaced apart from the substrate by a predetermined distance, and a connection portion connecting the two portions, and thereby by mechanical driving thereof. Dispersion of the generated stress to ensure mechanical stability, and the spacer 72 to prevent the ribbon 55 and the lower electrode 75 is in contact with each other is characterized in that the structure to enhance the reliability of the optical modulator.

As described above, the optical modulator of the present invention and a method of manufacturing the same include a ribbon exposed through an opening on an upper plate, power lines and pads capable of supplying different power to each of the ribbons, and a voltage difference between the ribbon and the lower plate. The lower electrode which selectively causes the ribbon to drive the ribbon, and a pad for selectively supplying power to the ribbon of the upper plate are provided to bond the upper plate and the lower plate, thereby forming the ribbon in a bar shape parallel to the substrate rather than a bridge type. Effectively disperses the stress generated by the mechanical drive of the ribbon, thereby increasing the mechanical reliability,

The drive of the ribbon, which is the end of the ribbon, is formed to have a plurality of protrusions, and is formed in a structure that is cross-inserted with the protrusions of the ribbon facing each other, so that a ribbon having a thin width that is not easy to manufacture in a conventional manner By implementing the same, a larger number of ribbons can be secured in the same area, thereby improving the light modulation efficiency.

In addition, by using a spacer, the ribbon and the lower electrode are bonded during operation to prevent the occurrence of a problem that cannot be used later, thereby increasing the reliability of the operation, increasing the yield, reducing the manufacturing price and mass production. There is an effect to make this possible.

Claims (9)

A first insulating layer disposed on the bottom surface of the upper substrate; Exposed through openings formed in the upper substrate and the first insulating layer to face each other on both sides, and the arrangement on one side thereof is alternately bonded to the bottom surface of the first insulating layer, the opposite end side is a plurality of A plurality of first ribbons and a plurality of second ribbons each having a shape of a protrusion and intersecting with the protrusions facing each of the protrusions and spaced apart from each other by a predetermined distance; A plurality of ribbon pads disposed on a bottom surface of the first insulating layer and configured to apply a voltage to the plurality of first ribbons; A power supply line bent at both sides of the opening of the upper substrate and the first insulating layer to apply voltage to the plurality of second ribbons; A second insulating layer insulating the power line and the plurality of first ribbons; A lower electrode pad bonded to the power line through solder; A lower electrode connected to the lower electrode pad and positioned at a predetermined distance apart from the exposed portions of the first and second ribbons; A spacer spaced apart from the lower electrode by a predetermined distance and having a step higher than that of the lower electrode; A plurality of pads connected to the ribbon pads through solder; And a third insulating layer and a lower substrate for supporting the respective structures. delete The optical modulator of claim 1, wherein the first and second ribbons have a stacked structure of a metal layer and a first insulating layer. The optical modulator of claim 1, wherein the spacer has a stacked structure of a lower substrate having a step difference higher than that of another region and the third insulating layer. delete The method of claim 1, wherein the second insulating layer is located only on the upper side of the power line, and a plurality of independent contact holes are located in a plurality of positions, and the power line and the second ribbon are connected through the contact hole. An optical modulator, insulated from the first ribbon and the power line. The optical modulator of claim 1, wherein the first insulating layer is a silicon nitride film, and a region where solder of the lower substrate is located is a groove region having a step difference lower than that of other substrate regions. Forming a plurality of first ribbons connected to the power line on the upper substrate, and forming a second ribbon not connected to the power line, and etching the upper substrate from the center of the bottom surface to form the first ribbon and the second ribbon. A top plate manufacturing step of manufacturing the top plate by exposing the end side of the top plate; Depositing an insulating layer on the lower substrate on which the groove and the spacer are formed, forming a first pad connected to the lower electrode and the lower electrode on the insulating layer, and forming a second pad located in the groove. Manufacturing step; The lower plate and the upper plate are formed using a solder located in the groove so that the lower substrate is positioned on the uppermost layer on the bottom of the lower substrate, and the pads connected to the second pad of the lower plate and the first ribbon of the upper plate are connected to each other. An optical modulator manufacturing method comprising a bonding process for bonding the line pad and the first pad of the lower plate to be connected. 10. The method of claim 8, wherein the first ribbon and the second ribbon are deposited after patterning the aluminum, the ribbon is different from the driving characteristics on both sides of the opening of the first insulating layer and the arrangement on one side is driven An optical modulator having a structure in which ribbons having different characteristics are alternately positioned, and end faces of the opposite ribbons have a plurality of protrusion shapes and are cross-inserted so that each protrusion is spaced apart from each other. Manufacturing method.