JP2006208426A - Optical switch and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical switch in which the anodes of a first substrate furnished with an optical fiber and a second substrate where an actuator part with a movable mirror part is formed are easily connected. <P>SOLUTION: The optical switch is composed of the first substrate having an optical waveguide layer having at least a plurality of optical paths in which light propagates, and the second substrate in which the actuator part furnished with a movable mirror part which changes the optical path in which the light propagates among the plurality of the optical paths is formed. A glass film including alkaline metal is formed on the surface or in the surface part of the optical waveguide layer of the first substrate and the anodes of the first substrate and the second substrate are connected. The connected part of the anode of the respective substrates is an outer edge part and the plane-contact part of the second substrate except the anode which is made contact with the first substrate has a recessed part lower than the anode-connection part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical switch and a manufacturing method thereof.

  Some optical switches used in an optical communication system include an electrostatic actuator for switching the traveling direction of output light between a plurality of optical fibers that are waveguides. The electrostatic actuator includes a support arm having a mirror attached to the tip, and a drive system that moves the support arm so that the mirror is inserted and removed between the optical fibers. (For example, see Patent Document 1)

  A base member, a first optical fiber and a second optical fiber disposed on the base member so that the end faces face each other, and a base member provided in the axial direction of the first optical fiber and the second optical fiber An extending movable member, an optical component fixed to the movable member so as to be positioned between the first optical fiber and the second optical fiber, and reflecting light emitted from the first optical fiber; Driving means for driving the movable member so that the optical component moves between a first position for reflecting the emitted light and a second position for passing the light emitted from the first optical fiber toward the second optical fiber; By providing the movable member with the optical components fixed in this manner on the base member so as to extend in the axial direction of the first optical fiber and the second optical fiber, First light It is possible to narrow the space occupied of the movable member with respect to Aiba and perpendicular to the axis of the second optical fiber (the width direction of the optical switch). Thereby, it becomes possible to reduce the size of the optical switch in the width direction. Further, high integration can be achieved by arraying optical switches in the width direction.

FIG. 3 is a horizontal sectional view of an optical switch according to the prior art, and FIG. 4 is a vertical sectional view. The optical switch 1 includes a base substrate 2, a groove 3, a fiber positioning V-groove 4, optical fibers 5a to 5d (MEMS structure 6), a MEMS substrate 7, an electrostatic actuator 8, a position holding actuator 9, and a cantilever beam. 10, comb tooth part 11, support part 12, mirror part 13, light reflecting surface 13a, electrode 14, comb tooth part 15, voltage source 16, movable member 17, elastic body 18, comb tooth part 19, locking projection part 20, a latch receiving portion 21, an electrode 22, a comb tooth portion 23, and a voltage portion 24.
The base substrate 2 and the MEMS structure 6 are bonded.

JP 2004-191643 A

  The base substrate 2 as the first substrate and the second substrate as the MEMS substrate 7 are anodically bonded. However, if there is a foreign substance on the surface of the MEMS substrate 7, the anodic bonding between the first substrate and the second substrate is performed. I can't.

  The present invention has been made in view of the above problems, and enables anodic bonding of the first substrate and the second substrate even if foreign matter exists on the surface of the second substrate without increasing the number of manufacturing steps. The purpose is to do.

  At least a first substrate having an optical waveguide layer having a plurality of optical paths through which light can propagate, and a second substrate having an actuator section provided with a movable mirror section that changes an optical path through which light propagates among the plurality of optical paths. An optical switch configured to form a glass film containing an alkali metal on or in the surface portion of the first substrate optical waveguide layer, and anodically bonding the first substrate and the second substrate, wherein the anode The joining portion is an outer edge portion of each substrate, and the portion other than the anode joining portion of the second substrate that is in surface contact with the first substrate is an optical switch formed in a recess so as to be lower than the anode joining portion.

  The second substrate is a silicon laminate in which at least an intermediate layer is sandwiched between a silicon substrate and a silicon active layer, and the movable mirror portion and the concave portion are optical switches formed in the silicon active layer.

  An optical switch manufacturing method comprising at least an optical waveguide layer having a plurality of optical paths through which light can propagate, and a movable part that changes an optical path through which light propagates among the plurality of optical paths, on a first substrate, The optical waveguide layer is formed, a glass film containing an alkali metal is formed on the surface of the optical waveguide layer or in a surface layer portion, a movable portion in which a mirror portion is provided on a second substrate, and the movable portion is the first portion. A beam portion that supports two substrates is formed, and the first substrate and the second substrate are anodically bonded, thereby integrating the optical waveguide layer and a movable portion that changes an optical path through which the light propagates. An optical switch manufacturing method is provided.

  The second substrate is at least a silicon laminate in which an intermediate layer is sandwiched between a silicon substrate and a silicon active layer, and a first masking step for forming a first masking pattern on the surface of the silicon active layer; , Using the first masking pattern as a mask, removing the silicon active layer in the exposed region by dry etching, removing the first masking pattern, and forming a second masking pattern on the surface of the silicon active layer Forming a second masking step, using the second masking pattern as a mask, removing a predetermined amount of the silicon active layer in an exposed region by dry etching, and removing the second masking pattern; The recess is formed by exposing the silicon active layer in the exposed region using the first masking pattern as a mask. A manufacturing method of an optical switch formed in the process of removing by dry etching.

  According to the present invention, when the first substrate and the second substrate are bonded together, a part of the surface of the silicon active layer of the second substrate that comes into contact with the first substrate by anodic bonding is dry-etched in the process. By removing in the process, the contact area between the first substrate and the second substrate is reduced, and even if foreign matter is present on the surface of the silicon active layer of the second substrate, it is difficult to contact the first substrate. Therefore, the optical switch can be manufactured by performing anodic bonding of the first substrate and the second substrate without increasing the number of manufacturing steps.

  At least a first substrate having an optical waveguide layer having a plurality of optical paths through which light can propagate, and a second substrate having an actuator section provided with a movable mirror section that changes an optical path through which light propagates among the plurality of optical paths. An optical switch configured to form a glass film containing an alkali metal on or in the surface portion of the optical waveguide layer of the first substrate, and anodically bonding the first substrate and the second substrate, The anodic bonding portion is an outer edge portion of each substrate, and a portion other than the anodic bonding portion of the second substrate that is in surface contact with the first substrate is an optical switch formed in a recess so as to be lower than the anodic bonding portion.

FIG. 1 is a view for explaining a method of manufacturing an optical switch according to the present invention, and is a cross-sectional view of an essential part for each step (cross section AA in FIG. 2B). The same steps as those of the prior art shown in the figure are omitted. FIG. 2A is a completed perspective view of the second substrate, and FIG. 2B is a top view of the second substrate. The first embodiment of the present invention will be described below with reference to FIGS. In addition, it abbreviate | omits about the manufacturing method of a 1st board | substrate.
Step (a): The second substrate is a silicon laminate (SOI substrate) 31 including a silicon active layer 31a (for example, 100 μm), an intermediate layer 31b (for example, 2 μm), and a silicon support substrate 31c (for example, 400 μm). First, a masking resistant film 32 is formed on the entire surface of the silicon active layer 31a by sputtering or the like. The resistant film 32 is made of, for example, chromium (Cr) and is resistant to hydrofluoric acid (HF) used in deep anisotropic reactive ion etching and wet etching of silicon processing.
Step (b): The resistant film 32 formed in the previous step is patterned into a desired pattern shape by wet etching to form a first masking pattern 32a (for mirror portion formation). When patterning, first, a photosensitive resist (positive type) (not shown) is uniformly applied to the upper surface of the resistant film 32 by spin coating. After coating, the photosensitive resist is covered with a photomask having a desired masking pattern shape, and the photosensitive resist is exposed to ultraviolet rays. After the exposure, the exposed region of the photosensitive resist is removed using a developer. Thereafter, using the photosensitive resist pattern formed by the above steps as a mask, the resistant film 32 in the exposed region is removed by wet etching. Thereafter, the photosensitive resist is removed by an organic solvent (such as acetone) or O2 ashing.
Step (c): A masking resistant film 33 is newly formed on the entire surface of the silicon active layer 31a including the upper surface of the first masking pattern 32a formed in the previous step (b). The resistant film 33 is made of, for example, a photosensitive resist (positive type) and is uniformly applied by spin coating.
Step (d) The resistant film 33 formed in the previous step (c) is patterned into a desired pattern shape by exposure and development as in the previous step (b) to form a second masking pattern 33a.
Step (e): Using the second masking pattern 33a formed in the previous step (d) as a mask, the exposed region of the silicon active layer 31a is subjected to deep anisotropic reactive ion etching to be an intermediate layer serving as an etching stop layer. Remove until layer 31b is exposed. At this point, part of the region in contact with the first substrate is also removed by deep anisotropic reactive ion etching until the intermediate layer 31b which is an etching stop layer is exposed. As a result, a concave portion 37 that does not come into contact with the first substrate is formed in the majority other than the outer edge portion to be anodically bonded.
Step (f): The second masking pattern 33a used as a mask in the previous step (e) is removed by an organic solvent (acetone or the like) or O ₂ ashing.
Step (g): Using the first masking pattern 32a exposed by removing the second masking pattern 33a in the previous step (f) as a mask, the silicon active layer 31a in the exposed region is subjected to a deep anisotropic reaction. A certain amount (for example, 50 μm in the depth direction) is removed by reactive ion etching. Thereby, the mirror part 34 is formed in the silicon active layer 31a.
Step (h): The first masking pattern 32a used as a mask in the previous step (g) is removed by wet etching.
Step (i): The intermediate layer 31b is selectively removed by isotropic wet etching except for a part, and the movable portion 35 is separated from the silicon support substrate 31c. As an etchant used for wet etching, for example, hydrofluoric acid (HF) may be used, but other etchants may be used as long as they selectively etch only the intermediate layer 31b.
Step (j): The optical waveguide layer 36 made of the first substrate and the second substrate (MEMS chip) 31 completed in the previous step are aligned and overlapped with each other. Alignment is performed using an aligner. Next, the superposed optical waveguide layer 36 and the MEMS chip 31 are placed in a heating furnace. In this heating furnace, lead wires are connected to the stationary portions of the optical waveguide chip substrate 36 and the MEMS chip 31, respectively. The inside of the heating furnace is evacuated to remove moisture contained in the air remaining in the heating furnace. Further, the inside of the heating furnace may be replaced with dry nitrogen gas or dry air. After heating the heating furnace to about 400 ° C., a DC voltage of about 300 V is applied to a lead wire (not shown) connected to the optical waveguide layer 36 and the MEMS chip 31, and both are bonded together by anodic bonding. Needless to say, a concave portion is formed on the surface of the first substrate facing the movable portion formed on the second substrate.

Although the mirror part and the mirror movable part, which are the main parts of the optical switch, are formed with an SOI substrate and a recess for reducing the contact surface with the first substrate is formed in the manufacturing process, anodic bonding becomes easy. The manufacturing process remains the same.

  Even when a columnar etching residue is generated on the surface of the recess forming part due to small foreign matter, dirt, etc., in the manufacturing method of the present invention, there is no problem because it is removed along with the removal of the intermediate layer of the columnar lower part in step (i). As for the size, in the present embodiment, the size of the lower surface of the mirror portion, which is the largest in the movable portion, is removed.

It is a figure for demonstrating the manufacturing method of the optical switch by this invention, and is principal part sectional drawing for every process (A) is a completed perspective view of the second substrate, (b) is a top view of the second substrate. Horizontal cross-sectional view of a conventional optical switch Vertical section of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical switch 2 Base board 3 Groove part 4 Fiber positioning V groove 5a Optical fiber 5b Optical fiber 5c Optical fiber 5d Optical fiber 6 MEMS structure 7 MEMS board 8 Electrostatic actuator 9 Position holding actuator 10 Cantilever 11 Comb tooth part DESCRIPTION OF SYMBOLS 12 Support part 13 Mirror part 13a Light reflecting surface 14 Electrode 15 Comb part 16 Voltage source 17 Movable member 18 Elastic body 19 Comb part 20 Locking projection part 21 Locking receiving part 22 Electrode 23 Comb part 24 Voltage part 31 Silicon laminated body 31a Silicon active layer 31b Intermediate layer 31c Silicon support substrate 32 Resistance film 32a First masking pattern 33 Resistance film 33a Second masking pattern 34 Mirror part 35 Movable part 36 Optical waveguide layer

Claims (4)

At least a first substrate having an optical waveguide layer having a plurality of optical paths through which light can propagate, and a second substrate having an actuator section provided with a movable mirror section that changes an optical path through which light propagates among the plurality of optical paths. An optical switch configured to form a glass film containing an alkali metal on or in the surface portion of the optical waveguide layer of the first substrate, and anodically bonding the first substrate and the second substrate, The light is characterized in that the anodic bonding portion is an outer edge portion of each substrate, and a concave portion is formed so that a portion other than the anodic bonding portion of the second substrate that is in surface contact with the first substrate is lower than the anodic bonding portion. switch. The second substrate is a silicon laminate in which at least an intermediate layer is sandwiched between a silicon substrate and a silicon active layer, and the movable mirror portion and the recess are formed in the silicon active layer. The optical switch according to claim 1. An optical switch manufacturing method comprising at least an optical waveguide layer having a plurality of optical paths through which light can propagate, and a movable part that changes an optical path through which light propagates among the plurality of optical paths, on a first substrate, The optical waveguide layer is formed, a glass film containing an alkali metal is formed on the surface of the optical waveguide layer or in a surface layer portion, a movable portion in which a mirror portion is provided on a second substrate, and the movable portion is the first portion. A beam portion that supports two substrates is formed, and the first substrate and the second substrate are anodically bonded, thereby integrating the optical waveguide layer and a movable portion that changes an optical path through which the light propagates. A method for manufacturing an optical switch. The second substrate is at least a silicon laminate in which an intermediate layer is sandwiched between a silicon substrate and a silicon active layer, and a first masking step for forming a first masking pattern on the surface of the silicon active layer; , Using the first masking pattern as a mask, removing the silicon active layer in the exposed region by dry etching, removing the first masking pattern, and forming a second masking pattern on the surface of the silicon active layer Forming a second masking step, using the second masking pattern as a mask, removing a predetermined amount of the silicon active layer in an exposed region by dry etching, and removing the second masking pattern; The recess is formed by exposing the silicon active layer in the exposed region using the first masking pattern as a mask. The method of manufacturing an optical switch according to claim 3, wherein the forming in the process of removing by dry etching.

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