JP2004333887A - Manufacturing method of optical switch device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to manufacture an optical switch device provided with minute millers movable in a high yield state of a nondefective product. <P>SOLUTION: A mirror chip 109 is formed by cutting and dividing a mirror substrate 100 in the state protected by cementing a mount film (1st adhesive film) 106 with an adhesive layer varying in adhesion on the surface formed with the mirrors 105 of the mirror substrate 100, and the mirror chip 109 is removed after reducing the adhesion of the adhesive layer of the mount film 106. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of manufacturing an optical switch device used for an optical switch device used for communication, measurement, display, etc. using switching.
[0002]
[Prior art]
2. Description of the Related Art There is an optical switch device manufactured using a micromachine technology for performing three-dimensional microfabrication by etching based on a thin film forming technology or a photolithography technology (see Non-Patent Document 1). This optical switch device has an electrode that is a fixed structure and a mirror that is a movable reflection structure. The mirror which is a movable reflection structure has a support and a movable member, and the movable member is connected to the support member by a spring member such as a torsion spring. The optical switch configured as described above performs a switching operation of switching the optical path by changing the attitude of the mirror by an attractive force or a repulsive force acting between the electrode as the fixed structure and the mirror as the movable reflective structure.
[0003]
Among the manufacturing methods of such an optical switch device, a method of joining a mirror chip and an electrode chip has been proposed (see Non-Patent Document 2). This mounting method will be described with reference to FIG.
First, as shown in FIG. 3A, a mirror substrate 303 having a movable mirror 302 is manufactured using an SOI (Silicon on Insulator) substrate having a buried insulating layer 301. The mirror 302 is formed by finely processing the SOI layer 304 made of single crystal silicon below the buried insulating layer 301.
[0004]
FIG. 3B is a plan view of the mirror 302 shown in FIG. The mirror 302 has a circular shape with a diameter of about 500 μm, and is connected to the movable frame 306 by a pair of mirror connecting portions 305. Further, the movable frame 306 is connected to the surrounding SOI layer 304 by a pair of connecting portions 307. The mirror connecting portion 305 and the connecting portion 307 are bar-shaped or plate-shaped spring members, such as torsion bar springs, which are elastically deformed by being twisted. By connecting with such a spring member, for example, the mirror 302 rotates around a rotation axis passing through the pair of mirror connecting portions 305.
[0005]
In order to drive the mirror 302, an electrode that is arranged to be opposed to the mirror 302 at a predetermined distance is provided. For this purpose, as described below, the mirror substrate 303 is cut out to form a mirror chip. Then, the electrode tip on which the electrode is formed is joined to this.
After the final step of the wafer manufacturing process, the mirror substrate 303 is first conveyed to a film pasting device, and a mount film 309 is pasted on the silicon substrate layer 308 of the mirror substrate 303 as shown in FIG. Can be
[0006]
The mirror substrate 303 affixed to the mount film 309 is diced and divided by a dicing device to form a mirror chip 310 having one mirror. After dividing into individual mirror chips 310, one of the mirror chips 310 is removed from the mount film 309 (FIG. 3D).
Thereafter, as shown in FIG. 3E, the SOI layer 304 of the mirror chip 310 is brought into contact with the bonding layer 312 of the electrode chip 311 prepared in advance by a flip chip bonder or the like, and thermocompression bonding is performed. And join them.
[0007]
As a result, an optical switch device including the electrode 313 that is arranged to face the mirror 302 at a predetermined distance is obtained. As the electrode chip 311, an electrode substrate provided with the electrode 313 may be manufactured, and this may be divided by dicing into an electrode chip 311 similarly to the mirror chip. The bonding layer 312 is a metal layer such as Au.
[0008]
[Non-patent document 1]
Y. -A. Peter et al. , "Optical MEMS for adaptive optics applications," Electrochemical Society Proceedings Volume 2002-4, pp. 361-367
[Non-patent document 2]
"Two-Axis Comb-Driven MEMS Mirror Array for Three-Dimensional Optical Switch Featuring Low-Voltage Operation," Osamu Tsuboi and 8 other authors, IEICE Communications Society Conference, 2002, B-12-3, p. 443
[0009]
[Problems to be solved by the invention]
By the way, the optical switch device has a rotating fine mirror structure, and has low mechanical strength and is fragile. For this reason, there is a problem that the mirror portion is destroyed by vibration accompanying cutting when cutting into chips or a water flow used for cooling during cutting. For example, particularly low mechanical strength portions such as the mirror connecting portion 305 and the connecting portion 307 shown in FIG. 3 are easily damaged.
[0010]
Even if the optical switch device can be manufactured without destroying the mirror portion, great care must be taken in handling the chip of the optical switch device in order to prevent the movable portion from being destroyed.
Furthermore, in the conventional manufacturing method, since the light reflecting surface of the mirror is exposed, the fine wafer shavings pass through gaps between the connecting portions and the like to the mirror surface when dicing into chips. This causes a problem that dust adheres and dust adheres at the time of storage or handling before mounting, and the light reflectance is reduced.
[0011]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to manufacture an optical switch device having a fine mirror that can move with a high yield of non-defective products.
[0012]
[Means for Solving the Problems]
The method for manufacturing an optical switch device according to the present invention includes the steps of: forming a first adhesive film provided with an adhesive layer having a variable adhesive force on a surface of a mirror substrate formed by arranging a plurality of rotating mirrors; A first step of attaching, a second step of attaching a second adhesive film to the back surface of the mirror substrate, and a third step of dividing the mirror substrate into a plurality of mirror chips by making a cut from the second adhesive film side. A fourth step of reducing the adhesive strength of the adhesive layer of the first adhesive film, and a fifth step of removing the mirror chip from the first adhesive film in a state where the adhesive strength of the adhesive layer of the first adhesive film is reduced. A step of preparing an electrode chip provided with electrodes and bonding a mirror chip to the electrode chip; and a seventh step of peeling the second adhesive film from the mirror chip bonded to the electrode chip. It is obtained by a process.
According to this manufacturing method, when the mirror substrate is divided into the mirror chips, the rotating mirror portion is fixed to the first adhesive film together with the surrounding portion.
[0013]
In the above-described method for manufacturing an optical switch device, an ultraviolet-curable adhesive film whose adhesive strength is reduced by irradiation of ultraviolet light is used as the first adhesive film, and in the fourth step, the first adhesive film is irradiated with ultraviolet light. Alternatively, the adhesive strength of the adhesive layer may be reduced.
[0014]
Further, as the first pressure-sensitive adhesive film, a temperature-sensitive pressure-sensitive adhesive film in which the state of the pressure-sensitive adhesive layer changes and the pressure-sensitive adhesive force is reduced by setting the temperature to a predetermined temperature or higher is used. By setting the temperature to be equal to or higher than the temperature, the adhesive strength of the adhesive layer may be reduced.
Further, as the first pressure-sensitive adhesive film, a temperature-sensitive pressure-sensitive adhesive film in which the state of the pressure-sensitive adhesive layer changes to lower the pressure-sensitive adhesive force by lowering the temperature to a predetermined temperature or less is used. The adhesive strength of the adhesive layer may be reduced by setting the temperature to be equal to or lower than the temperature.
[0015]
In the above-described method for manufacturing an optical switch device, an ultraviolet-curable adhesive film whose adhesive strength is reduced by irradiation of ultraviolet light is used as the second adhesive film, and in the seventh step, the second adhesive film is irradiated with ultraviolet light. After that, the second adhesive film may be peeled off.
Further, as the second pressure-sensitive adhesive film, a temperature-sensitive pressure-sensitive adhesive film in which the state of the pressure-sensitive adhesive layer is changed by lowering or higher than a predetermined temperature to lower the pressure-sensitive adhesive force is used, and in the seventh step, the second pressure-sensitive adhesive film is used. The temperature may be set to be equal to or higher than a predetermined temperature or lower and then the second adhesive film may be peeled off.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 are process diagrams showing an example of a method for manufacturing an optical switch device according to the present embodiment. First, as shown in FIG. 1A, a groove 103a is formed from the side (main surface) of the SOI substrate 101 where the buried insulating layer 102 is formed by a known photolithography technique and etching such as DEEP RIE. Thus, the shape of the mirror and the movable frame is formed in the single crystal silicon layer 103 over the buried insulating layer 102.
[0017]
At this time, a metal film such as Au may be formed on the surface of the mirror in order to improve the reflectance of the mirror. In the DEEP RIE, for example, when silicon is dry-etched, SF ₆ and C ₄ F ₈ gases are alternately introduced, and the etching and the formation of the sidewall protective film are repeated, so that the groove having an aspect ratio of 50 is obtained. Alternatively, this is a technique in which holes are formed at an etching rate of several μm per minute.
[0018]
Next, as shown in FIG. 1B, a resist pattern 120 having an opening for forming a mirror is formed on the back surface of the SOI substrate 101, and the resist pattern 120 is etched from the back surface of the SOI substrate 101 using an etching solution such as an aqueous solution of potassium hydroxide. Selectively etch silicon. In this etching, an opening is formed on the back surface of the SOI substrate 101 corresponding to the mirror formation region using the buried insulating layer 102 as an etching stopper layer. Next, a region exposed in the opening of the buried insulating layer 102 is selectively removed using hydrofluoric acid.
[0019]
Thereafter, the resist pattern 120 is removed, and as shown in FIG. 1C, a plurality of rotatable mirrors 105 are provided on the single crystal silicon layer 103 supported on the SOI substrate 101 via the buried insulating layer 102. The formed mirror substrate 100 is obtained. Although not shown in FIG. 1, a movable frame is formed outside each mirror 105. Here, FIG. 1 schematically shows a cross section of a part of a mirror substrate 100 in which a plurality of mirrors 103 are formed in a matrix.
[0020]
As described above, after the mirror substrate 100 is formed, as shown in FIG. 1D, a mount film (first adhesive film) 106 is formed on the surface of the single crystal silicon layer 103 on which the mirror 105 is formed. Paste. The mount film 106 is an ultraviolet curable adhesive film. The ultraviolet curable pressure-sensitive adhesive film is a pressure-sensitive adhesive film in which the pressure-sensitive adhesive that forms the pressure-sensitive adhesive layer undergoes curing shrinkage due to ultraviolet irradiation, and the stress reduces the pressure-sensitive adhesiveness of the pressure-sensitive adhesive layer. 1D and thereafter, the mirror substrate 100 is shown rotated by 180 °.
[0021]
Next, as shown in FIG. 1E, a mount film (second adhesive film) 107 is also attached to the surface of the SOI substrate 101 where the opening is formed. The mount film 107 does not need to be an ultraviolet-curable adhesive film. The mounting film 106 and the mounting film 107 may be attached by using the roller 108 and rolling the roller 108 from one side of the mirror substrate 100 to the other side and press-bonding the same.
[0022]
As described above, after attaching the mount films 106 and 107, the mirror substrate 100 is cut and divided from the mount film 107 side by making a cut using, for example, a diamond blade. For example, as shown in FIG. 2A, the mirror chip 109 is divided by cutting along a virtual line A. Thus, the mirror substrate 100 is divided into a plurality of mirror chips 109 each including one mirror 105 in a 1 mm square area.
[0023]
In this cutting, since the mirror 105 is fixed by the mount film 106, it is possible to prevent the mirror 105 from being damaged due to external vibration or impact during cutting.
In addition, since it is protected by the mount film 107, the cutting powder does not adhere to the portion of the mirror 105 at the time of cutting, so that the turning operation of the mirror 105 is prevented and deterioration does not occur. Further, the water flow at the time of cutting does not directly hit the mirror 105.
[0024]
As described above, after the mirror chip 109 is formed, the mount film 106 is irradiated with ultraviolet rays to reduce the adhesion (adhesion) between the mirror 105 and the mount film 106. As a result, the mirror chip 109 can be picked up from the mount film 106 without receiving a force that breaks the mirror 105.
[0025]
On the other hand, an electrode tip is formed as follows. First, a plurality of concave structures are formed by selectively etching a silicon substrate using a predetermined mask pattern made of a silicon nitride film or a silicon oxide film as a mask. Next, a metal film is formed on these concave structures by a vapor deposition method or the like, and the metal film is patterned by a photolithography technique using a known ultra-deep exposure and an etching technique, and an electrode part is formed at the bottom of each concave part. Form.
[0026]
Finally, these are divided by dicing to form an electrode tip 201 having an electrode 202 in a concave portion, as shown in FIG. 2C. When the electrode 202 of the electrode chip 201 is joined to the mirror chip 109, the electrode 202 is opposed to the mirror 105 by a predetermined distance. Note that a metal film 203 is provided on a portion of the electrode chip 201 in contact with the mirror chip 109. The electrode chip 201 is die-bonded to a package (not shown).
[0027]
As described above, when the mirror chip 109 and the electrode chip 201 are prepared, as shown in FIG. 2D, the surface of the single crystal silicon layer 103 of the mirror chip 109 and the surface of the metal film 203 of the electrode chip 201 are formed. Are bonded by thermocompression bonding. For these bonding, for example, a flip chip bonder may be used. Further, after bonding the mirror chip 109 and the electrode chip 201, a pad (not shown) connected to the electrode 202 and an external connection terminal are connected by wire bonding or the like. One of the external connection terminals is electrically connected to the mirror chip 109 via the metal film 203.
[0028]
Finally, by peeling off the mount film 107, an optical switch device in which the mirror chip 109 is connected to the electrode chip 201 is obtained as shown in FIG. In this optical switch device, for example, the mirror 105 is fixed to a ground (ground) potential, a driving potential is applied to the electrode 202, and an electrostatic force is generated between the mirror 105 and the electrode 202. By generating a rotational moment at 105, the mirror 105 rotates.
[0029]
According to the present embodiment described above, first, when the mirror substrate is divided into the mirror chips, the ultraviolet curable adhesive films are stuck on both surfaces of the mirror substrate for protection. As a result, it is possible to form a mirror chip without damaging the mirror portion when dividing the mirror chip into mirror chips.
[0030]
Moreover, the adhesiveness of the film attached to the surface on which the mirror is formed can be reduced by irradiating the film with ultraviolet light. Therefore, by irradiating the ultraviolet rays to reduce the adhesive strength, the divided mirror chips can be easily picked up, and the mirrors are not damaged at this stage.
In addition, since the ultraviolet curable adhesive film that has been split at the same time as the mirror chip is attached to the back surface of the mirror chip, handling when joining the mirror chip and the electrode chip is facilitated.
[0031]
By the way, in the above embodiment, the ultraviolet-curable adhesive film is used as the mount film with which the mirror comes in contact. However, it is not limited to this as long as the adhesive force (adhesive force) between the mirror chip and the mount film can be adjusted. is not. For example, a temperature-sensitive adhesive film may be used as a mount film with which the mirror is in contact, by raising the temperature to 100 ° C. or higher, the crystalline state of the adhesive changes, and the adhesive strength decreases. Alternatively, a temperature-sensitive adhesive film of a type in which, by setting the temperature to, for example, −20 ° C. or lower, the crystalline state of the adhesive changes to reduce the adhesive strength. Furthermore, a temperature-sensitive adhesive film of a type in which the temperature is increased to 100 ° C. or more, whereby the fine particles of the adhesive expand and the adhesive strength is reduced.
[0032]
Further, in the present embodiment, the mount film capable of changing the adhesive force is used only on the surface in contact with the mirror, but it goes without saying that a similar film may be used on the surface where the mirror is not formed. No. For example, an ultraviolet curable adhesive film may be used for the mount film 107, and the mount film 107 may be separated from the mirror chip after being irradiated with ultraviolet light. Similarly, a temperature-sensitive adhesive film may be used for the mount film 107, and the mount film 107 may be peeled from the mirror chip at a predetermined temperature or higher or lower.
[0033]
【The invention's effect】
As described above, in the present invention, the mirror substrate is cut and divided in a state where the first adhesive film having the adhesive layer whose adhesive force changes is adhered and protected on the surface of the mirror substrate where the mirror is formed. A mirror chip was formed, and the adhesive force of the adhesive layer was reduced before removing the mirror chip. As a result, according to the present invention, it is possible to protect the mirror portion from various situations when dividing the mirror chip into mirror chips, and to provide an optical switch device having a fine mirror that can move with a high yield rate of non-defective products. An excellent effect of being able to manufacture is obtained.
[Brief description of the drawings]
FIG. 1 is a process chart illustrating an example of a manufacturing method according to an embodiment of the present invention.
FIG. 2 is a process drawing following FIG. 1 for explaining an example of a manufacturing method in the embodiment of the present invention.
FIG. 3 is a process chart for explaining a conventional manufacturing method.
[Explanation of symbols]
100: mirror substrate, 101: SOI substrate, 102: embedded insulating layer, 103: single crystal silicon layer, 103a: groove, 105: mirror, 106: mount film (first adhesive film), 107: mount film (second adhesive) Film: 108, Roller, 109: Mirror chip, 201: Electrode chip, 202: Electrode, 203: Metal film.

Claims (7)

A first step of attaching a first adhesive film provided with an adhesive layer having a variable adhesive force to a surface of the mirror substrate on which the plurality of rotating mirrors are arranged and formed on the mirror,
A second step of attaching a second adhesive film to the back surface of the mirror substrate;
A third step of dividing the mirror substrate into a plurality of mirror chips by making a cut from the second adhesive film side;
A fourth step of reducing the adhesive strength of the adhesive layer of the first adhesive film,
A fifth step of removing the mirror chip from the first adhesive film while the adhesive force of the adhesive layer of the first adhesive film is reduced,
A sixth step of preparing an electrode chip provided with electrodes and joining the mirror chip to the electrode chip;
And a seventh step of separating the second adhesive film from the mirror chip bonded to the electrode chip. The method for manufacturing an optical switch device according to claim 1,
The first pressure-sensitive adhesive film is an ultraviolet-curable pressure-sensitive adhesive film in which the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer is reduced by irradiation with ultraviolet light,
In the fourth step, a method for manufacturing an optical switch device, characterized in that the first adhesive film is irradiated with ultraviolet rays to reduce the adhesive strength of the adhesive layer. The method for manufacturing an optical switch device according to claim 1,
The first pressure-sensitive adhesive film is a temperature-sensitive pressure-sensitive adhesive film in which the state of the pressure-sensitive adhesive layer changes by lowering the temperature to a predetermined temperature to lower the adhesive strength,
In the fourth step, a method of manufacturing an optical switch device, wherein the adhesive force of the adhesive layer is reduced by setting the first adhesive film to a predetermined temperature or higher. The method for manufacturing an optical switch device according to claim 1,
The first pressure-sensitive adhesive film is a temperature-sensitive pressure-sensitive adhesive film in which the state of the pressure-sensitive adhesive layer is changed by lowering the temperature to a predetermined temperature or lower to reduce the pressure-sensitive adhesive strength,
In the fourth step, a method for manufacturing an optical switch device, wherein the adhesive force of the adhesive layer is reduced by lowering the temperature of the first adhesive film to a predetermined temperature or lower. The method for manufacturing an optical switch device according to any one of claims 1 to 4,
The second pressure-sensitive adhesive film is a UV-curable pressure-sensitive adhesive film in which the pressure-sensitive adhesive layer has a reduced adhesive strength by irradiation with ultraviolet light,
The method of manufacturing an optical switch device, wherein in the seventh step, the second pressure-sensitive adhesive film is irradiated with ultraviolet rays and then the second pressure-sensitive adhesive film is peeled off. The method for manufacturing an optical switch device according to any one of claims 1 to 4,
The second pressure-sensitive adhesive film is a temperature-sensitive pressure-sensitive adhesive film in which the state of the pressure-sensitive adhesive layer changes by setting the temperature to a predetermined temperature or more, and the pressure-sensitive adhesive strength is reduced.
The method for manufacturing an optical switch device, wherein in the seventh step, the second adhesive film is peeled after the second adhesive film is heated to a predetermined temperature or higher. The method for manufacturing an optical switch device according to any one of claims 1 to 4,
The second pressure-sensitive adhesive film is a temperature-sensitive pressure-sensitive adhesive film in which the state of the pressure-sensitive adhesive layer changes by lowering the temperature to a predetermined temperature or lower to lower the pressure-sensitive adhesive strength,
The method of manufacturing an optical switch device according to claim 7, wherein in the seventh step, the second adhesive film is released after the temperature of the second adhesive film is set to a predetermined temperature or lower.

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